Insights into Antimicrobial Potential of Styrylquinoline Derivatives

Insights into Antimicrobial Potential of Styrylquinoline Derivatives | Research Square window.SnipcartSettings = { analytics: { enabled: false } }; (function() { var accessVector = localStorage.getItem('access_vector') || ''; window.dataLayer = window.dataLayer || []; if (accessVector) { window.dataLayer.push({ user: { profile: { profileInfo: { snid: accessVector } } } }); } })(); (function(w,d,s,l,i){w[l]=w[l]||[];w[l].push({'gtm.start':new Date().getTime(),event:'gtm.js'});var f=d.getElementsByTagName(s)[0],j=d.createElement(s),dl=l!='dataLayer'?'&l='+l:'';j.async=true;j.src='https://www.googletagmanager.com/gtm.js?id='+i+dl;f.parentNode.insertBefore(j,f);})(window,document,'script','dataLayer','GTM-K279D39R'); Browse Preprints In Review Journals COVID-19 Preprints AJE Video Bytes Research Tools Research Promotion AJE Professional Editing AJE Rubriq About Preprint Platform In Review Editorial Policies Our Team Advisory Board Help Center Sign In Submit a Preprint Cite Share Download PDF Article Insights into Antimicrobial Potential of Styrylquinoline Derivatives Wioleta Cieślik, Anna Mrozek-Wilczkiewicz, Alois Cizek, Robert Musioł, and 1 more This is a preprint; it has not been peer reviewed by a journal. https://doi.org/ 10.21203/rs.3.rs-9163171/v1 This work is licensed under a CC BY 4.0 License Status: Under Review Version 1 posted 6 You are reading this latest preprint version Abstract A total of 64 ring-substituted 2-styrylquinolines were designed and tested against a battery of microbial pathogens: Staphylococcus aureus ATCC 29213, Enterococcus faecalis ATCC 29212, clinical isolates of methicillin-resistant S. aureus (MRSA), Mycobacteium tuberculosis H37Ra/ATCC 25177, Mycobacterium smegmatis ATCC 700084, Mycobacterium kansasii DSM 44162, Candida albicans CCM 8361, Candida krusei CCM 8271 and Candida parapsilosis CCM 8260. In addition, all compounds were investigated for their anticancer potential on colon cancer cell lines HCT 116 p53+/+ and HCT 116 p53-/- as well as the effect against normal human dermal fibroblasts (NHDF). Twenty derivatives showed remarkable antimicrobial activity comparable to or better than clinically used drugs (ampicillin, ciprofloxacin, rifampicin, amphotericin B). The most effective compounds were substituted on styryl with 2,6-Cl, 2-NO 2 , 2,4-NO 2 , 4-CN, 2-OAc-5-Cl and 2-OH-5-NO 2 . Chlorination of the quinoline at the 5- and 7-position and the free hydroxylic group at the 8-position of the quinoline resulted in increased and broadened efficacy. All the antimicrobial active derivatives did not show significant effect on normal human dermal fibroblasts, except for 2,6-Cl-styryl derivatives. The antimycobacterial active compounds were able to inhibit cellular respiration in all tested mycobacterial species. ( E )-5,7-dichloro-2-[2-(2-nitrophenyl)vinyl]-quinolin-8-ol ( D4 ) and ( E )-5,7-dichloro-2-[2-(2,4-dinitrophenyl)vinyl]-quinolin-8-ol ( D10 ) were the most antimicrobial effective agents simultaneously with high anticancer activity and negligible cytotoxicity against normal human cells. Thus, promising active agents with dual, anti-infectious, and anticancer effects, were identified. Biological sciences/Cancer Biological sciences/Drug discovery Biological sciences/Microbiology Styrylquinolines synthesis antibacterial activity antimycobacterial activity antifungal activity antiproliferative effect Figures Figure 1 1. Introduction In the first decade of the 21st century, the "antibiotic era" gradually changed into the "post-antibiotic era". Infectious pathogens, which have been under control since the 1950s thanks to the strong onset of various antibacterial, antituberculosis and antifungal drugs, are increasingly getting out of control and becoming resistant to the used drugs, and the current state of development of new anti-infective drugs is extremely worrying 1–3 . It is undeniable that the increasing microbial load and the development of antimicrobial resistance (AMR) pose a major threat to human health worldwide. The number of deaths associated/caused by AMR is gradually increasing. The main pathogens for resistance-related deaths are Staphylococcus aureus , Escherichia coli , Klebsiella pneumoniae , Streptococcus pneumoniae , Acinetobacter baumannii , and Pseudomonas aeruginosa . Another high number of deaths is due to M. tuberculosis (resistant, multi-resistant, extensively resistant and totally resistant strains). Increasingly frequent infections with non-tuberculous (atypical) strains of mycobacteria causing severe infections of the lungs, bones, digestive system, skin and other soft organs are related to the overall reduced immunity of the human population 4–7 . In addition to the increased risk of patient death, AMR also results in longer hospital stays and increased healthcare costs 4,8,9 . It is understandable that this condition is extremely undesirable in the absence of appropriate treatment and drugs. Currently, various approaches try to overcome the lack of effective drugs. In addition to the application of various synergistic combinations, drug repurposing or nanoparticle (technological) improvements, designing new entities with a new/innovative mechanism of action or with a multi-target effect is considered the most advantageous 10–19 . This last interesting approach is aimed at the search/design of molecules with multiple mechanisms of action and is used mainly for anti-infective and anticancer drugs, when it is necessary to overcome the resistance 20 . Interestingly, therapeutics active across the species with a so-called dual effect, i.e. with antimicrobial and anticancer or antimicrobial and antiparasitic, etc., can be also found 20–30 . The search for compounds with dual activity is crucial for developing innovative therapeutics that can address multidrug resistance and complex diseases. Such compounds are identified through various methods, including high-throughput screening of natural products and synthetic libraries, computational drug repurposing, and structure-activity relationship (SAR) studies to optimize their efficacy and selectivity. This approach aligns with the concept of privileged structures, which are molecular frameworks frequently found in bioactive compounds and capable of interacting with multiple biological targets. By focusing on such structural motifs, researchers can enhance the likelihood of discovering dual-acting agents through rational drug design, fragment-based screening, and scaffold-hopping strategies. Azanaphthalenes, specifically quinolines and especially 8-hydroxyquinolines (8-HQ), are a source of such multi-target agents. It is therefore not surprising that 8-HQs have a wide range of biological properties and can therefore be considered as privileged structures of multi-target agents 31–34 . The simple 8-HQ scaffold has unique physicochemical properties and affords the possibility of a large number of modifications (via targeted or diversity-directed synthesis) 34–39 . On the other hand, all these compounds show a mechanism of action that is complex and difficult to determine (e.g. 34–36,38,39 ): they are able to chelate various metals 40–44 and affect various enzymatic systems 34,37,39,45–49 . Despite this, quinoline-based compounds form an important scaffold in medicinal chemistry 32,34,35,38 , mainly used for the design of anti-infective 35,39,46–52 and anticancer agents 41,44,45,53–58 . It is important to mention that halogenated derivatives of 8-HQ have been approved for their antiseptic use many years ago 59–63 . This contribution is a continuation of the work of our team and deals with the evaluation of antimicrobial (antibacterial, antimycobacterial, antifungal) activity of synthesized ring-substituted 2-styrylquinoline derivatives 64–69 . The discussed compounds were also tested for their anticancer effect 53,54 , and therefore suitable molecules with only anticancer or anti-infection potential, or with a dual (anticancer + antimicrobial) effect, can be selected from the biologically investigated compounds in this way. 2. Materials and Methods 2.1. Compounds All styrylquinoline derivatives investigated in this study were synthesized according to previously reported procedures 53 . Detailed synthetic protocols, purification methods, and physicochemical characterization data for all new compounds are provided in the Supplementary Material. 2.2. Biological Studies 2.2.1. Test Microorganisms Standard reference bacterial strains Staphylococcus aureus ATCC 29213, Enterococcus faecalis ATCC 2921, Mycobacteium tuberculosis H37Ra/ATCC 25177, Mycobacteium smegmatis ATCC 700084, and Mycobacteium kansasii DSM 44162 were obtained from American Type Culture Collection (ATCC). Clinical isolates of methicillin-resistant S. aureus SA 3202, SA 630 70 were obtained from a collection of the National Institute of Public Health, Prague, Czech Republic, and 63718 70 from a collection of the Department of Infectious Diseases and Microbiology, Faculty of Veterinary Medicine, University of Veterinary Sciences Brno, Czech Republic. Candida albicans CCM 8261, Candida krusei CCM 8271, and Candida parapsilosis CCM 8260 were obtained from a collection of the Czech Collection of Microorganisms, Brno, Czech Republic 71 . 2.2.2. Determination of Bacterial Minimum Inhibitory Concentration Minimum inhibitory concentrations (MICs) were determined using a broth microdilution method in accordance with CLSI guidelines 72 , with minor modifications described previously 73 . Stock solutions of the compounds were prepared in DMSO (10 µg/mL) and further diluted in appropriate media: Cation Adjusted Mueller–Hinton broth (CaMH, Oxoid) for staphylococci, brain heart infusion (BHI, Oxoid) for enterococci, and Middlebrook 7H9 (Oxoid) for mycobacteria, to obtain final concentrations ranging from 256 to 0.125 µg/mL. Microplates were inoculated with the tested microorganisms. The final inoculum density was 1.5 × 10⁶ CFU/mL for M. tuberculosis and 10⁵ CFU/mL for the remaining bacteria. Ampicillin, ciprofloxacin, and rifampicin (Sigma) were used as reference drugs. Drug-free and sterility controls were included. Plates were incubated under appropriate conditions (24 h at 37°C for staphylococci and enterococci, 3 days for M. smegmatis , and 14 days for M. tuberculosis and M. kansasii ). MIC values were defined as the lowest concentration completely inhibiting visible growth. For M. tuberculosis , MIC determination was performed using the Alamar Blue assay (Oxoid). Following incubation, Alamar Blue reagent (10% v/v) was added, and plates were further incubated for 24 h. The MIC was defined as the lowest concentration preventing the color change from blue (resazurin) to pink (resorufin). All experiments were performed in triplicate. 2.2.3. MTT Assay The MTT assay was performed as previously described 74–77 , with minor modifications. Compounds were dissolved and diluted in appropriate media (CaMH for staphylococci and Middlebrook 7H9 for mycobacteria) to final concentrations ranging from 256 to 0.0625 µg/mL. Bacterial suspensions were prepared at standard densities and added to microplate wells containing the tested compounds. Control wells without compounds were included, and ciprofloxacin (Sigma) served as a positive control. Samples were prepared in duplicate. After incubation under appropriate conditions (24 h for staphylococci, 3 days for M. smegmatis , and 14 days for M. tuberculosis and M. kansasii ), MTT reagent was added to each well (10% v/v), followed by further incubation to allow formazan formation. The reaction was stopped by addition of sodium dodecyl sulfate solution, and absorbance was measured at 570 nm. Cell viability was expressed as a percentage relative to untreated controls using the ratio of absorbance values. A reduction in viability below 70% was considered indicative of cytotoxic activity. The results are presented in Tables 2 and 3 . 2.2.4. Determination of Minimum Fungistatic Activity The minimum fungistatic inhibitory concentrations were evaluated by the microdilution broth method according to the CLSI 78 with some modifications as described previously 73 . The compounds were dissolved in DMSO (Sigma) to get concentration 10 µg/mL and diluted in RPMI-1640 medium (Sigma) to concentrations of 256–1 µg/mL. To prepare fungal inoculum in RPMI-1640 broth, the microorganisms were grown on Sabourad dextrose agar (Sigma) at 37°C for 24 h ( C. albicans , C. krusei ) and for 48 h ( C. parapsilosis ). The plate was then inoculated with a pipette, the final concentration of fungal cells was 5×10 2 CFU/mL in each well. The plate was incubated in 37°C for 24 h or 48 h. After incubation the minimal fungistatic concentration was evaluated as a minimal concentration of tested compounds, which visibly inhibited the fungal growth. 2.2.5. Cell Viability Assay The human colorectal carcinoma cell line HCT 116 with wild type of p53 (p53 +/+ ) were obtained from the ATCC. HCT 116 with deletion of TP53 gene (p53 −/− ) was provided from Maria Sklodowska-Curie Memorial Cancer Center and Institute of Oncology in Gliwice, Poland. The normal human dermal fibroblast cell line (NHDF) was purchased from PromoCell (Heidelberg, Germany). A recently described procedure 53 was used. The results are shown in Table 1 . 3. Results and Discussion 3.1. Chemistry The investigated styrylquinoline derivatives were synthesized using commercially available quinaldines I–III as starting materials. The synthetic route involved an initial condensation step with appropriate aromatic aldehydes (Scheme 1 ), performed in a boiling mixture of acetic anhydride and 80% acetic acid (3:1, v/v). Under these conditions, all hydroxyl groups present in the substrates underwent acylation, requiring a subsequent deprotection step to regenerate the corresponding hydroxyl functionalities. Selective removal of acetyl groups was achieved using either pyridine/water or potassium carbonate in methanol (Scheme 2 ). Treatment with pyridine/water resulted in preferential deacylation of the hydroxyl group substituted with the quinoline moiety, while the acetyl group on the phenyl ring remained intact. In contrast, the use of potassium carbonate in methanol at room temperature enabled complete deprotection of all hydroxyl groups. These approaches allowed for controlled and selective deacylation of styrylquinoline derivatives depending on the reaction conditions. Sixty-four compounds were prepared in this way, of which 59 have been previously reported, see 53,54 . Derivatives D8 , D11 , D12 , D13 and E2 are novel, have not been described in the literature, and their characteristics are listed in the Supplementary Material. All the discussed compounds were classified into 5 groups according to their structure: A1 – 15 (2-[( E )-2-arylethenyl]quinolin-8-yl acetates), B1 – 7 (2-[( E )-2-arylethenyl]quinolin-8-ols), C1 – 23 (5,7-dichloro-2-[( E )-2-arylethenyl]quinolin-8-yl acetates), D1 – 15 (5,7-dichloro-2-[( E )-2-arylethenyl]quinolin-8-ols), E1 – 4 (2-[( E )-2-arylethenyl]quinolin-4-ols). Their structures and individual substitutions are presented in Table 1 . Since lipophilicity is a key parameter affecting the fate of all bioactive agents 79,80 and influencing their activity 81 , lipophilicity values expressed as log P were estimated for all compounds, see Table 1 . Log P values were calculated using ACD/Percepta ver. 2012 (Advanced Chemistry Development. Inc., Toronto, ON, Canada, 2012). Compounds of series A exhibited log P values in the range from 3.51 to 5.22, their deacetylated derivatives of series B had log P value in the range 3.35–5.04. 5,7-Dichlorinated derivatives of series C had log P ranging from 5.10 to 7.11; while the range of log P values of series D was 5.33–7.04. Compounds of series E had log P values in the range from 3.73 to 5.53. Thus it can be concluded that all the investigated derivatives are rather lipophilic substances. In general, ( E )-2-[2-(2-acetoxyphenyl)vinyl]quinolin-8-ol ( B2 ) is the least lipophilic (log P = 3.35), while ( E )-5,7-dichloro-2-[2-(2-acetoxy-3,5-dichlorophenyl)vinyl]quinolin-8-yl acetate ( C20 ) is the most lipophilic (log P = 7.11) of all the discussed compounds. It can be assumed that lipophilicities increase in the series B < A < D < C. But this only applies to halogen-type substitutions on styryl. If NO 2 or CN is used as substituents, a change in order can be traced and the prediction software assigns the C-series compounds higher lipophilicity than the D-series compounds ( C1 – 6 < D1 – 6 ) probably due to intramolecular interactions. The compounds of group E appear to have log P values between those of groups A and D. In addition, the electronic σ parameters illustrating the effect of substituents of the phenyl ring of styryl tail were predicted. These σ parameters are in a wide range from 0.01 (2-OEt), i.e., rather with the properties of donating electrons to the system, up to ~ 1.6 (2,6-F-3-Cl, 2,4-NO 2 ), i.e., with a very strong electron-withdrawing effect. Also, these σ parameters were predicted using ACD/Percepta ver. 2012. 3.2. Biology As mentioned above, most of the compounds have been previously described when their anticancer potential was investigated 53,54 . By comparing the IC 50 values obtained against colon cancer cell lines HCT 116 p53 +/+ and HCT 116 p53 −/− versus normal human dermal fibroblasts (NHDF), their possible therapeutic potential can be seen. Five new compounds were also tested on these human cell lines and all IC 50 values are shown in Table 1 . Considering the previous positive antimicrobial results of selected styrylquinoline derivatives 47,64–68,82 , all the discussed derivatives were subjected to extensive in vitro screening against Gram-positive bacteria, mycobacteria, and candida. First, universally susceptible collection strains of Staphylococcus aureus ATCC 29213 and Enterococcus faecalis ATCC 29212 were selected. Some of the compounds were effective against S. aureus , so testing continued on staphylococcal strains with an epidemiologically significant type of resistance; clinical isolates of methicillin-resistant Staphylococcus aureus (MRSA) of human and veterinary origin (SA 3202, SA 630, 63718) carrying the mecA gene were selected 70 . Unfortunately, none of the compounds showed activity against facultatively anaerobic E. faecalis , so other similar types of bacteria or resistant isolates of E. faecalis were not tested. All the compounds were also in vitro tested against Mycobacteium tuberculosis H37Ra/ATCC 25177 and additionally against Mycobacterium smegmatis ATCC 700084 and Mycobacterium kansasii DSM 44162 as representatives of non-tuberculous mycobacteria causing increasingly frequent and difficult-to-treat mycobacterial infections, especially in immunocompromised patients 7 . M. tuberculosis and M. kansasii are slow-growing mycobacteria, while M. smegmatis is a fast-growing strain. In addition, all the compounds were in vitro tested against three representatives of yeasts: Candida albicans CCM 8361, Candida krusei CCM 8271, Candida parapsilosis CCM 8260. Activities are expressed as the minimum inhibitory concentrations (MICs); see Table 1 . Looking at the results from Table 1 and comparing the MIC values of the discussed compounds with their antiproliferative values against cancer cells, it can be stated that the compounds showed greater anticancer activity for which they were primarily designed. Of the 64 compounds, only 20 derivatives showed remarkable antimicrobial activity. From series A, compounds A2 (R = 3-OMe, log P = 4.02, σ = 0.66) and A7 (R = 2-Cl, log P = 4.46, σ = 1.05) were selective against mycobacteria, and derivative A9 (R = 2-NO 2 , log P = 3.78, σ = 1.12) selective against Candida sp. On the other hand, agent A13 (R = 2,6-Cl, log P = 5.20, σ = 1.33) was effective in the entire spectrum of tested microorganisms (except E. faecalis ). All compounds showed insignificant effect against normal human fibroblasts (NHDF). From series B, compound B4 (R = 2-NO 2 , log P = 3.64, σ = 1.12) was selective against Candida sp. (similar to series A) and derivative B5 (R = 3,5-OMe, log P = 3.93, σ = 0.93) showed selective antistaphylococcal activity. Similar to series A, agent B6 (R = 2,6-Cl, log P = 5.04, σ = 1.33) was effective across the tested spectrum. All compounds also showed negligible activity against NHDF. By comparing the antimicrobial activities and physicochemical parameters of compounds from series A and B, it can be concluded that lipophilicity does not play a fundamental role in the activity, electronic parameters partially influence the activity (a higher value of σ is advantageous), but the nature and position of the substituents on the phenyl ring of styryl are most significant for the activity (compare the effects of A12 , A13 , A14 ). It can be assumed that the hydroxyl group of the quinoline ring is advantageous for activity against staphylococci, compared the activity of A11 / B5 (R = 3,5-OMe), as described e.g., 64,68,83 . On the other hand, deacetylation of the C 8 -hydroxylic group did not affect the activity when styryl was substituted with 2-NO 2 or 2,6-Cl (comparable activity of acetylated/deacetylated compounds A9 / B4 , A13 / B6 ). Within series C, compounds C1 (R = 2-Cl, log P 6.17, σ = 1.05) and C5 (R = 4-CN, log P 5.39, σ = 1.05) were selective against mycobacteria, while derivative C3 (R = 2-CN, log P 6.17, σ = 1.04) showed selective antistaphylococcal activity. On the other hand, compound C6 (R = 2-NO 2 , log P = 5.27, σ = 1.12), probably due to chlorination of the quinoline ring nucleus, extended the activity from anticandidal to antistaphylococcal activity as well (as described e.g., by 84,85 . Traditionally, agent C11 (R = 2,6-Cl, log P = 7.10, σ = 1.33) was the most potent derivative against the entire spectrum of microorganisms. As a result of the chlorination of 8-acetoxyquinoline (8-AcQ) (and thus higher lipophilicity), there was also an increase in activity compared to derivative A13 . The increase in antimicrobial activity associated with higher lipophilicity (chlorination of 8-AcQ) is also associated with higher antiproliferative activity not only against HCT 116 cancer cell lines but also against NHDF cells ( C11 had an IC 50 = 9.55 µM on NHDF). Group D showed the highest amount of active substances. In general, halogenation of 8-HQ, i.e. higher lipophilicity leads to higher potency and subsequent deacetylation (release) of the quinoline hydroxyl group further increases activity. Importantly, there was no undesirable increase in antiproliferative activity against NHDF as in the case of the acetylated series C, although the most successful 2,6-Cl styryl substitution (compound D8 ) showing the highest activity against the tested microorganisms showed comparable adverse effects against NHDF (IC 50 = 6.22 µM) along with C11 ; other derivatives showed an insignificant effect on NHDF cells. As in the previous case with series C, compounds D1 (R = 2-CN, log P = 5.65, σ = 1.04) demonstrated selective antistaphylococcal activity and D3 (R = 4-CN, log P = 5.71, σ = 1.05) selective antimycobacterial activity. In the case of derivative D4 (R = 2-NO 2 , log P = 5.45, σ = 1.12), in comparison with the series A, B and C, not only was the activity strengthened, but also its expansion from the original anticandidal to antistaphylococcal and finally to antimycobacterial efficacy. After hydrolysis of the acyl group in the 8-position of the quinoline ring, derivative D10 (R = 2,4-NO2, log P = 5.33, σ = 1.66) was activated, which was completely inactive in the series A and C. Along with the above-mentioned changes on the quinoline core, new derivatives were activated: D11 (R = 2-OH-5-Cl, log P = 6.25, σ = 1.04) acquired anticandidal and antimycobacterial activity, D13 (R = 2-OH-5-NO 2 , log P = 5.68, σ = 1.28) acquired antistaphylococcal and antimycobacterial and especially D12 (R = 2-OAc-5-Cl, log P = 6.18, σ = 0.18) obtained an effect against the entire spectrum of microorganisms. The last and smallest series E, where the hydroxylic group from position 8 of the quinoline was moved to position 4, were completely inactive. 5,7-Dichloro-8-hydroxyquinoline derivatives (series D) exhibit the broadest spectrum of biological activity among the tested compounds. The most potent agents are those bearing a 2,6-dichloro substitution in the styryl tail (compounds C11 and D8 ). However, these derivatives also demonstrate relatively high toxicity toward normal human NHDF cells. Consequently, the optimal balance between antimicrobial efficacy and safety appears to be achieved by derivatives D4 (featuring a 2-NO₂ group) and D10 (bearing 2,4-NO₂ groups). In addition to their antimicrobial properties, both D4 and D10 show excellent antitumor activity, with IC₅₀ values ranging from 0.54 to 0.76 µM (Fig. 1 ). It is also worth noting that despite the very low MIC values achieved by some standard drugs (e.g. CPX, RIF), the tested compounds exhibit unique properties – not only strong activity against SA strains, but also an extended spectrum of activity including MRSA strains, mycobacterial pathogens (MT, MS, MK) and Candida fungi. Differences in activity against individual microorganisms may result from interactions specific to the structure of cell walls and mechanisms of penetration through the lipid barrier, which opens new perspectives in the design of drugs with a broad spectrum of action. Since the compounds exhibit activity against aerobic staphylococci but not against facultatively anaerobic enterococci 86–89 , suggested that their mechanism of action may be associated with interference in respiratory processes 90 . To verify this hypothesis, an MTT assay was performed for the most active derivatives. This assay enables indirect evaluation of bacterial viability through measurement of metabolic activity. A decrease in respiratory activity below 70% of the control level after exposure to MIC concentrations was considered indicative of a positive effect. Such reduction in oxidative metabolism reflects impaired cellular function and suggests involvement of respiration-related mechanisms 74,77 . The lowest MIC multiples required to achieve > 70% reduction in viability of S. aureus ATCC 29213 and MRSA isolate SA 3202 are presented in Table 2 . Compounds A13/B6/C11/D8 (R = 2,6-Cl) and D12 (R = 2-OAc-5-Cl) did not show any significant inhibition in the MTT assay, even at the highest tested concentration (256 µg/mL). In contrast, compounds D1 (R = 2-CN), D10 (R = 2,4-NO2), and D13 (R = 2-OH-5-NO2) exhibited only limited inhibition at elevated MIC values. These results indicate that, despite pronounced antibacterial activity against staphylococci, the tested styrylquinoline derivatives do not primarily affect cellular respiration and may act via alternative mechanisms. Notably, comparable activity was observed against both methicillin-susceptible S. aureus and MRSA strains, suggesting that the presence of the mecA gene, responsible for methicillin resistance 70,91 , does not influence the efficacy of these compounds. This supports the hypothesis of a distinct mode of action specific to Staphylococcus spp. Table 2 Lowest MIC values with at least 70% inhibition of respiratory activity of staphylococcal strains. No. SA resp. inh. (Conc.) MRSA1 resp. inh. (Conc.) D1 96.6% (8× MIC) 92.6% (2× MIC) D10 96.6% (4× MIC) 84.5% (8× MIC) D13 80.6% (32× MIC) 83.1% (32× MIC) CPX 92.5% (32× MIC) 96.5% (32× MIC) SA = Staphyloccoccus aureus ATCC 29213; MRSA1 = clinical isolate of methicillin-resistant S. aureus SA 3202; CPX = ciprofloxacin Quinoline derivatives are known to exhibit antimycobacterial activity, which is often associated with inhibition of mycobacterial ATP synthase and disruption of cellular respiration 48,92,93 . Therefore, in addition to MIC determination, an MTT assay was performed for the most active compounds. Similarly to the previous analysis, a reduction in respiratory activity of mycobacterial cells below 70% of the control after exposure to MIC concentrations was considered indicative of a positive result 74–76 . The lowest MIC multiples required to achieve more than 70% inhibition of mycobacterial viability are summarized in Table 3 . Compound A7 (R = 2-Cl) showed inhibition of respiration at 1× MIC across all tested mycobacterial species. In contrast, disubstituted derivatives A13/B6/C11/D8 (R = 2,6-Cl) did not exhibit any detectable MTT inhibition, even at the highest tested concentration (256 µg/mL), similarly to the observations for staphylococci. On the other hand, the remaining highly active compounds ( C5 , D1 , D10 , D13 ) demonstrated pronounced inhibition of the mycobacterial respiratory chain not only at MIC values but also at sub-MIC concentrations, in some cases as low as one-sixteenth of the MIC (e.g., C5/D1 , R = 4-CN, against M. smegmatis ). These findings suggest that derivatives bearing 2,6-dichloro substitution may act via a mechanism distinct from other active styrylquinoline derivatives. Table 3 Lowest MIC values with at least 70% inhibition of respiratory activity of mycobacterial strains. No. MT resp. inh. (Conc.) MS resp. inh. (Conc.) MK resp. inh. (Conc.) A7 75.3% (1× MIC) 91.0% (1× MIC 87.5% (0.5× MIC C5 89.5% (0.5× MIC) 90.6% (0.063× MIC) 90.9% (0.5× MIC) D1 92.8% (0.5× MIC) 92.3% (0.063× MIC) 91.4% (0.5× MIC) D10 94.4% (1× MIC) 86.8% (1× MIC) 92.3% (0.5× MIC) D13 87.5% (1× MIC) 88.0% (1× MIC) 87.7% (1× MIC) CPX 95.2% (32× MIC) 94.7% (64× MIC) 95.0% (64× MIC) MT = Mycobacteium tuberculosis H37Ra/ATCC 25177; MS = Mycobacteium smegmatis ATCC 700084, MK = Mycobacteium kansasii DSM 44162; CPX = ciprofloxacin This extensive antimicrobial screening succeeded in finding new multi-target agents with very good activity against a wide spectrum of microorganisms and a good safety profile. Either these are substances with a selective effect against mycobacteria ( A2 , A7 , C1 ), staphylococci ( B5 , C3 , D1 ) or candida ( A9 , B4 ) or, on the contrary, they are compounds with a broad spectrum of antimicrobial effect ( A13 , B6 , D4 , D10 , D11 , D12 , D13 ). Most of these compounds simultaneously demonstrated dual activity against colon cancer cell lines. 4. Conclusion Several compounds from a series of sixty-four ring-substituted 2-styrylquinolines tested against Gram-positive bacteria, slow- and fast-growing mycobacteria, and Candida sp. expressed activity comparable to or higher than clinically used drugs. Antimicrobial active compounds have also shown activity against colon cancer cell lines. Chlorination of the quinoline nucleus and the unsubstituted phenolic moiety at position 8 of quinoline positively affects antimicrobial activity. The crucial factor influencing the activity is not the lipophilicity itself or the electron-withdrawing properties of the styryl tail, but the type of substituent and, especially, the position of the substituents on the styryl. Positions C 2,6 ' substituted with chlorine, C 2 '/C 2,4 ' substituted with a nitro group are preferred. It has been shown that the compounds do not affect cellular respiration in staphylococci, on the other hand, they significantly inhibit cellular respiration in mycobacteria. Thus, this primary screening revealed promising multi-target agents with dual (antimicrobial+ anticancer) activity and insignificantly affecting non-cancerous human cells. Declarations Declarations of interest The authors declare no competing financial or non-financial interests. Ethical approval: Not required. Use of AI tools No generative AI tools were used in the writing or data analysis of this manuscript. Funding: This work was supported by the Polish National Science Center (Grant No. 2018/31/B/NZ7/02122). Author Contribution Conceptualization WC, JJ and RM; methodology WC, AMW, AC and JJ; investigation WC, AMW, AC and JJ; original draft preparation WC and JJ; review and editing WC, JJ and RM; project administration and funding acquisition RM. Acknowledgement The authors wish to thank Mrs. Ewelina Spaczyńska for her assistance with the syntheses. Data Availability Data are available from the corresponding author upon reasonable request. References Hansson, K. & Brenthel, A. Imagining a post-antibiotic era: a cultural analysis of crisis and antibiotic resistance. Med Humanit 48 , 381-388, doi:10.1136/medhum-2022-012409 (2022). Abdallah, E. M., Alhatlani, B. Y., de Paula Menezes, R. & Martins, C. H. G. Back to Nature: Medicinal Plants as Promising Sources for Antibacterial Drugs in the Post-Antibiotic Era. Plants (Basel) 12 , doi:10.3390/plants12173077 (2023). Rabi, M. The global (health) governance of antimicrobial resistance. Globalizations 21 , 1518-1538, doi:10.1080/14747731.2024.2375455 (2024). Antimicrobial resistance , (2024). Antimicrobial Resistance, C. Global burden of bacterial antimicrobial resistance in 2019: a systematic analysis. Lancet 399 , 629-655, doi:10.1016/S0140-6736(21)02724-0 (2022). (WHO, Geneva, Switzerland, 2023). Mirabal;, A. B., Nguyen;, A. & Ferrer, G. Lung Nontuberculous Mycobacterial Infections. , (StatPearls, 2024). Dadgostar, P. Antimicrobial Resistance: Implications and Costs. Infect Drug Resist 12 , 3903-3910, doi:10.2147/IDR.S234610 (2019). Poudel, A. N. et al. The economic burden of antibiotic resistance: A systematic review and meta-analysis. PLoS One 18 , e0285170, doi:10.1371/journal.pone.0285170 (2023). Jampilek, J. Design and Discovery of New Antibacterial Agents: Advances, Perspectives, Challenges. Curr Med Chem 25 , 4972-5006, doi:10.2174/0929867324666170918122633 (2018). Jampilek, J. Drug repurposing to overcome microbial resistance. Drug Discov Today 27 , 2028-2041, doi:10.1016/j.drudis.2022.05.006 (2022). Paul, D. et al. Artificial intelligence in drug discovery and development. Drug Discov Today 26 , 80-93, doi:10.1016/j.drudis.2020.10.010 (2021). Visan, A. I. & Negut, I. Integrating Artificial Intelligence for Drug Discovery in the Context of Revolutionizing Drug Delivery. Life (Basel) 14 , doi:10.3390/life14020233 (2024). Rudrapal, M., Paudel, K. R. & Pangeni, R. Editorial: Drug repurposing and polypharmacology: A synergistic approach in multi-target based drug discovery. Front Pharmacol 13 , 1101007, doi:10.3389/fphar.2022.1101007 (2022). Weth, F. R. et al. Unlocking hidden potential: advancements, approaches, and obstacles in repurposing drugs for cancer therapy. Br J Cancer 130 , 703-715, doi:10.1038/s41416-023-02502-9 (2024). Mamun, M. M., Sorinolu, A. J., Munir, M. & Vejerano, E. P. Nanoantibiotics: Functions and Properties at the Nanoscale to Combat Antibiotic Resistance. Front Chem 9 , 687660, doi:10.3389/fchem.2021.687660 (2021). Modi, S. et al. Nanostructured Antibiotics and Their Emerging Medicinal Applications: An Overview of Nanoantibiotics. Antibiotics 11 , 708 (2022). Yetisgin, A. A., Cetinel, S., Zuvin, M., Kosar, A. & Kutlu, O. Therapeutic Nanoparticles and Their Targeted Delivery Applications. Molecules 25 , doi:10.3390/molecules25092193 (2020). Li, M. et al. Recent advances in nanoantibiotics against multidrug-resistant bacteria. Nanoscale Adv 5 , 6278-6317, doi:10.1039/d3na00530e (2023). Chifiriuc, M. C. et al. Common themes in antimicrobial and anticancer drug resistance. Front Microbiol 13 , 960693, doi:10.3389/fmicb.2022.960693 (2022). Talevi, A. Multi-target pharmacology: possibilities and limitations of the "skeleton key approach" from a medicinal chemist perspective. Front Pharmacol 6 , 205, doi:10.3389/fphar.2015.00205 (2015). Kabir, A. & Muth, A. Polypharmacology: The science of multi-targeting molecules. Pharmacol Res 176 , 106055, doi:10.1016/j.phrs.2021.106055 (2022). Loscher, W. Single-Target Versus Multi-Target Drugs Versus Combinations of Drugs With Multiple Targets: Preclinical and Clinical Evidence for the Treatment or Prevention of Epilepsy. Front Pharmacol 12 , 730257, doi:10.3389/fphar.2021.730257 (2021). Makhoba, X. H., Viegas, C., Jr., Mosa, R. A., Viegas, F. P. D. & Pooe, O. J. Potential Impact of the Multi-Target Drug Approach in the Treatment of Some Complex Diseases. Drug Des Devel Ther 14 , 3235-3249, doi:10.2147/DDDT.S257494 (2020). Oselusi, S. O., Fadaka, A. O., Wyckoff, G. J. & Egieyeh, S. A. Computational Target-Based Screening of Anti-MRSA Natural Products Reveals Potential Multitarget Mechanisms of Action through Peptidoglycan Synthesis Proteins. ACS Omega 7 , 37896-37906, doi:10.1021/acsomega.2c05061 (2022). Doostmohammadi, A., Jooya, H., Ghorbanian, K., Gohari, S. & Dadashpour, M. Potentials and future perspectives of multi-target drugs in cancer treatment: the next generation anti-cancer agents. Cell Commun Signal 22 , 228, doi:10.1186/s12964-024-01607-9 (2024). Tran, D. N. et al. Dual anticancer and antibacterial activity of fluorescent naphthoimidazolium salts. RSC Adv 13 , 36430-36438, doi:10.1039/d3ra06555c (2023). Parchebafi, A. et al. The dual interaction of antimicrobial peptides on bacteria and cancer cells; mechanism of action and therapeutic strategies of nanostructures. Microb Cell Fact 21 , 118, doi:10.1186/s12934-022-01848-8 (2022). Dong, Z. et al. Anticancer Mechanisms and Potential Anticancer Applications of Antimicrobial Peptides and Their Nano Agents. Int J Nanomedicine 19 , 1017-1039, doi:10.2147/IJN.S445333 (2024). Tolos , A. M. et al. Anticancer Potential of Antimicrobial Peptides: Focus on Buforins. Polymers 16 , 728 (2024). Polanski, J., Kurczyk, A., Bak, A. & Musiol, R. Privileged structures - dream or reality: preferential organization of azanaphthalene scaffold. Curr Med Chem 19 , 1921-1945, doi:10.2174/092986712800167356 (2012). Solomon, V. R. & Lee, H. Quinoline as a privileged scaffold in cancer drug discovery. Current medicinal chemistry 18 , 1488-1508, doi:10.2174/092986711795328382 (2011). Song, Y. n., Xu, H., Chen, W., Zhan, P. & Liu, X. 8-Hydroxyquinoline: a privileged structure with a broad-ranging pharmacological potential. MedChemComm 6 , 61-74, doi:10.1039/C4MD00284A (2015). Gupta, R., Luxami, V. & Paul, K. Insights of 8-hydroxyquinolines: A novel target in medicinal chemistry. Bioorg Chem 108 , 104633, doi:10.1016/j.bioorg.2021.104633 (2021). Musiol, R., Mrozek-Wilczkiewicz, A. & Polanski, J. Synergy against fungal pathogens: working together is better than working alone. Curr Med Chem 21 , 870-893, doi:10.2174/0929867321666131218094848 (2014). Musiol, R., Serda, M., Hensel-Bielowka, S. & Polanski, J. Quinoline-based antifungals. Curr Med Chem 17 , 1960-1973, doi:10.2174/092986710791163966 (2010). Saadeh, H. A., Sweidan, K. A. & Mubarak, M. S. Recent Advances in the Synthesis and Biological Activity of 8-Hydroxyquinolines. Molecules 25 , 4321 (2020). Matada, B. S., Pattanashettar, R. & Yernale, N. G. A comprehensive review on the biological interest of quinoline and its derivatives. Bioorganic & Medicinal Chemistry 32 , 115973, doi:https://doi.org/10.1016/j.bmc.2020.115973 (2021). Dorababu, A. Recent update on antibacterial and antifungal activity of quinoline scaffolds. Archiv der Pharmazie 354 , 2000232 (2021). Prachayasittikul, V., Prachayasittikul, S., Ruchirawat, S. & Prachayasittikul, V. 8-Hydroxyquinolines: a review of their metal chelating properties and medicinal applications. Drug Des Devel Ther 7 , 1157-1178, doi:10.2147/dddt.S49763 (2013). Mrozek-Wilczkiewicz, A. et al. Investigating the anti-proliferative activity of styrylazanaphthalenes and azanaphthalenediones. Bioorg Med Chem 18 , 2664-2671, doi:10.1016/j.bmc.2010.02.025 (2010). Abeydeera, N. et al. Harnessing the Dual Antimicrobial Mechanism of Action with Fe(8-Hydroxyquinoline)(3) to Develop a Topical Ointment for Mupirocin-Resistant MRSA Infections. Antibiotics (Basel) 12 , doi:10.3390/antibiotics12050886 (2023). Yin, X.-D. et al. Design, Synthesis, and Antifungal Evaluation of 8-Hydroxyquinoline Metal Complexes against Phytopathogenic Fungi. Journal of Agricultural and Food Chemistry 68 , 11096-11104, doi:10.1021/acs.jafc.0c01322 (2020). Pivarcsik, T. et al. Metal Complexes of a 5-Nitro-8-Hydroxyquinoline-Proline Hybrid with Enhanced Water Solubility Targeting Multidrug Resistant Cancer Cells. Int J Mol Sci 24 , doi:10.3390/ijms24010593 (2022). Pape, V. F. S. et al. Structure-Activity Relationships of 8-Hydroxyquinoline-Derived Mannich Bases with Tertiary Amines Targeting Multidrug-Resistant Cancer. J Med Chem 65 , 7729-7745, doi:10.1021/acs.jmedchem.2c00076 (2022). Conan, P. et al. Identification of 8-Hydroxyquinoline Derivatives That Decrease Cystathionine Beta Synthase (CBS) Activity. Int J Mol Sci 23 , doi:10.3390/ijms23126769 (2022). Szczepaniak, J., Cieslik, W., Romanowicz, A., Musiol, R. & Krasowska, A. Blocking and dislocation of Candida albicans Cdr1p transporter by styrylquinolines. Int J Antimicrob Agents 50 , 171-176, doi:10.1016/j.ijantimicag.2017.01.044 (2017). Kos, J. et al. Ring-substituted 8-hydroxyquinoline-2-carboxanilides as potential antimycobacterial agents. Bioorg Med Chem 23 , 4188-4196, doi:10.1016/j.bmc.2015.06.047 (2015). Kushkevych, I., Vítězová, M., Kos, J., Kollár, P. & Jampílek, J. Effect of selected 8-hydroxyquinoline-2-carboxanilides on viability and sulfate metabolism of Desulfovibrio piger. Journal of Applied Biomedicine 16 , 241-246, doi:https://doi.org/10.1016/j.jab.2018.01.004 (2018). Joaquim, A. R. et al. Novel Antimicrobial 8-Hydroxyquinoline-Based Agents: Current Development, Structure-Activity Relationships, and Perspectives. J Med Chem 64 , 16349-16379, doi:10.1021/acs.jmedchem.1c01318 (2021). Kos, J. et al. 8-Hydroxyquinoline-2-carboxanilides as antiviral agents against avian influenza virus. ChemistrySelect 4 , 4582–4587, doi:10.1002/slct.201900873 (2019). Kumar, N. et al. Quinoline derivatives volunteering against antimicrobial resistance: rational approaches, design strategies, structure activity relationship and mechanistic insights. Mol Divers 27 , 1905-1934, doi:10.1007/s11030-022-10537-y (2023). Mrozek-Wilczkiewicz, A. et al. The synthesis and anticancer activity of 2-styrylquinoline derivatives. A p53 independent mechanism of action. Eur J Med Chem 177 , 338-349, doi:10.1016/j.ejmech.2019.05.061 (2019). Mrozek-Wilczkiewicz, A. et al. Design, Synthesis and In Vitro Activity of Anticancer Styrylquinolines. The p53 Independent Mechanism of Action. PLoS One 10 , e0142678, doi:10.1371/journal.pone.0142678 (2015). Kuczak, M., Cieślik, W., Musioł, R. & Mrozek-Wilczkiewicz, A. 4-Furanylvinylquinoline derivative as a new scaffold for the design of oxidative stress initiator and glucose transporter inhibitor drugs. Scientific Reports 14 , 28454, doi:10.1038/s41598-024-79698-0 (2024). Bissani, C., Gasparin, D. & Pilger, A. 8-Hydroxyquinoline, derivatives and metal-complexes: A review of antileukemia activities. ChemistrySelect 8 , doi:10.1002/slct.202204219 (2023). Czaplinska, B. et al. Comprehensive exploration of the optical and biological properties of new quinoline based cellular probes. Dyes and Pigments 144 , 119-132, doi:https://doi.org/10.1016/j.dyepig.2017.05.029 (2017). Gao, F., Zhang, X., Wang, T. & Xiao, J. Quinolone hybrids and their anti-cancer activities: An overview. European Journal of Medicinal Chemistry 165 , 59-79, doi:https://doi.org/10.1016/j.ejmech.2019.01.017 (2019). Cloxyguin , ( Clioquinol , ( Oxyquinoline , ( Chlorquinaldol , ( Dequalinium , ( Cieslik, W. et al. Contribution to investigation of antimicrobial activity of styrylquinolines. Bioorg Med Chem 20 , 6960-6968, doi:10.1016/j.bmc.2012.10.027 (2012). Cieslik, W. et al. Investigation of the antimycobacterial activity of 8-hydroxyquinolines. Med Chem 11 , 771-779, doi:10.2174/1573406410666150807111703 (2015). Jampilek, J. et al. Investigating biological activity spectrum for novel styrylquinazoline analogues. Molecules 14 , 4246-4265, doi:10.3390/molecules14104246 (2009). Musiol, R. et al. Antifungal properties of new series of quinoline derivatives. Bioorg Med Chem 14 , 3592-3598, doi:10.1016/j.bmc.2006.01.016 (2006). Musiol, R. et al. Investigating the activity spectrum for ring-substituted 8-hydroxyquinolines. Molecules 15 , 288-304, doi:10.3390/molecules15010288 (2010). Serda, M. et al. Investigation of the biological properties of (hetero)aromatic thiosemicarbazones. Molecules 17 , 13483-13502, doi:10.3390/molecules171113483 (2012). Zadrazilova, I. et al. In vitro bactericidal activity of 4- and 5-chloro-2-hydroxy-N-[1-oxo-1-(phenylamino)alkan-2-yl]benzamides against MRSA. Biomed Res Int 2015 , 349534, doi:10.1155/2015/349534 (2015). Czech Collection of Microorganisms, Brno, Czech Republic. National Committee for Clinical Laboratory Standards. Methods for Dilution Antimicrobial Susceptibility Tests for Bacteria that Grow Aerobically, 11th ed.; M07 . (NCCLS, 2018). R. Schwalbe, L. Steele-Moore & Goodwin, A. C. Antimicrobial Susceptibility Testing Protocols . (CRC Press, 2007). Measuring Cell Viability/Cytotoxicity. , ( Abate, G., Mshana, R. N. & Miorner, H. Evaluation of a colorimetric assay based on 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide (MTT) for rapid detection of rifampicin resistance in Mycobacterium tuberculosis. Int J Tuberc Lung Dis 2 , 1011-1016 (1998). Bueno, J. Antitubercular In Vitro Drug Discovery: Tools for Begin the Search, Understanding Tuberculosis - New Approaches to Fighting Against Drug Resistance . (InTech, 2011). Grela, E., Kozlowska, J. & Grabowiecka, A. Current methodology of MTT assay in bacteria - A review. Acta Histochem 120 , 303-311, doi:10.1016/j.acthis.2018.03.007 (2018). Alexander, B. D. et al. Reference Method for Broth Dilution Antifungal Susceptibility Testing of Yeasts: M27-A2. (Committee for Clinical Laboratory Standards, Wayne, PA, USA, 2017). Pliska, V., Testa, B. & van der Waterbeemd, H. Lipophilicity in Drug Action and Toxicology. , (Wiley-VCH: Weinheim, Germany, 1996). Culen, M., Rezacova, A., Jampilek, J. & Dohnal, J. Designing a dynamic dissolution method: a review of instrumental options and corresponding physiology of stomach and small intestine. J Pharm Sci 102 , 2995-3017, doi:10.1002/jps.23494 (2013). Kerns, E. H. & Di, L. Drug-Like Properties: Concepts. Structure Design and Methods: From ADME to Toxicity Optimization. , (Academic Press: San Diego, CA, USA, 2008). Cieslik, W., Szczepaniak, J., Krasowska, A. & Musiol, R. Antifungal Styryloquinolines as Candida albicans Efflux Pump Inhibitors: Styryloquinolines are ABC Transporter Inhibitors. Molecules 25 , doi:10.3390/molecules25020345 (2020). Zieba, A. et al. Design, Synthesis, and Anticancer and Antibacterial Activities of Quinoline-5-Sulfonamides. Molecules 29 , 4044 (2024). Dolezal, M. et al. Synthesis, antimycobacterial, antifungal and photosynthesis-inhibiting activity of chlorinated N-phenylpyrazine-2-carboxamides. Molecules 15 , 8567-8581, doi:10.3390/molecules15128567 (2010). Strharsky, T. et al. Study of Biological Activities and ADMET-Related Properties of Novel Chlorinated N-arylcinnamamides. Int J Mol Sci 23 , doi:10.3390/ijms23063159 (2022). Portela, C. A., Smart, K. F., Tumanov, S., Cook, G. M. & Villas-Bôas, S. G. Global metabolic response of Enterococcus faecalis to oxygen. J Bacteriol 196 , 2012-2022, doi:10.1128/jb.01354-13 (2014). Gilmore, M. S., Clewell, D. B., Ike, Y. & Shankar, N. Enterococci: From Commensals to Leading Causes of Drug Resistant Infection. , (Massachusetts Eye and Ear Infirmary, 2014). Ramos, S., Silva, V., Dapkevicius, M. L. E., Igrejas, G. & Poeta, P. Enterococci, from Harmless Bacteria to a Pathogen. Microorganisms 8 , doi:10.3390/microorganisms8081118 (2020). Gilmore, M. S. et al. Genes Contributing to the Unique Biology and Intrinsic Antibiotic Resistance of Enterococcus faecalis. mBio 11 , doi:10.1128/mBio.02962-20 (2020). Fraunfelter, V. M. et al. Quinoline Compounds Targeting the c-Ring of ATP Synthase Inhibit Drug-Resistant Pseudomonas aeruginosa. ACS Infect Dis 9 , 2448-2456, doi:10.1021/acsinfecdis.3c00317 (2023). Nubel, U. et al. A timescale for evolution, population expansion, and spatial spread of an emerging clone of methicillin-resistant Staphylococcus aureus. PLoS Pathog 6 , e1000855, doi:10.1371/journal.ppat.1000855 (2010). Bedaquiline , ( Mapari, M., Bhole, R. P., Khedekar, P. B. & Chikhale, R. V. Challenges in targeting mycobacterial ATP synthase: The known and beyond. Journal of Molecular Structure 1247 , 131331, doi:https://doi.org/10.1016/j.molstruc.2021.131331 (2022). Schemes Schemes 1 and 2 are available in the Supplementary Files section. Table 1 Table 1 is available in the Supplementary Files section. Additional Declarations No competing interests reported. Supplementary Files SupplementaryMaterial.docx scheme1.jpg Scheme 1. Synthesis of the studied compounds. scheme2.jpg Scheme 2. The hydrolysis of the acyl groups of the quinoline derivatives. 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09:54:45","extension":"jpg","order_by":2,"title":"","display":"","copyAsset":false,"role":"supplement","size":79277,"visible":true,"origin":"","legend":"\u003cp\u003e\u003cstrong\u003eScheme 1. \u003c/strong\u003eSynthesis of the studied compounds.\u003c/p\u003e","description":"","filename":"scheme1.jpg","url":"https://assets-eu.researchsquare.com/files/rs-9163171/v1/719df0ec2c4d266d420cc076.jpg"},{"id":108490995,"identity":"e2f96a5b-e2fe-495d-a51d-973805edd9fd","added_by":"auto","created_at":"2026-05-05 09:50:52","extension":"jpg","order_by":3,"title":"","display":"","copyAsset":false,"role":"supplement","size":47479,"visible":true,"origin":"","legend":"\u003cp\u003e\u003cstrong\u003eScheme 2. \u003c/strong\u003eThe hydrolysis of the acyl groups of the quinoline derivatives.\u003c/p\u003e","description":"","filename":"scheme2.jpg","url":"https://assets-eu.researchsquare.com/files/rs-9163171/v1/e9ae38a628dd654ce6bae646.jpg"},{"id":108201159,"identity":"8166657d-fc1b-4141-96ef-a4158a69cb3f","added_by":"auto","created_at":"2026-04-30 11:56:27","extension":"docx","order_by":4,"title":"","display":"","copyAsset":false,"role":"supplement","size":80198,"visible":true,"origin":"","legend":"","description":"","filename":"Table1.docx","url":"https://assets-eu.researchsquare.com/files/rs-9163171/v1/423f0e228b33431f13e99a8d.docx"}],"financialInterests":"No competing interests reported.","formattedTitle":"Insights into Antimicrobial Potential of Styrylquinoline Derivatives","fulltext":[{"header":"1. Introduction","content":"\u003cp\u003eIn the first decade of the 21st century, the \"antibiotic era\" gradually changed into the \"post-antibiotic era\". Infectious pathogens, which have been under control since the 1950s thanks to the strong onset of various antibacterial, antituberculosis and antifungal drugs, are increasingly getting out of control and becoming resistant to the used drugs, and the current state of development of new anti-infective drugs is extremely worrying \u003csup\u003e1\u0026ndash;3\u003c/sup\u003e. It is undeniable that the increasing microbial load and the development of antimicrobial resistance (AMR) pose a major threat to human health worldwide. The number of deaths associated/caused by AMR is gradually increasing. The main pathogens for resistance-related deaths are \u003cem\u003eStaphylococcus aureus\u003c/em\u003e, \u003cem\u003eEscherichia coli\u003c/em\u003e, \u003cem\u003eKlebsiella pneumoniae\u003c/em\u003e, \u003cem\u003eStreptococcus pneumoniae\u003c/em\u003e, \u003cem\u003eAcinetobacter baumannii\u003c/em\u003e, and \u003cem\u003ePseudomonas aeruginosa\u003c/em\u003e. Another high number of deaths is due to \u003cem\u003eM. tuberculosis\u003c/em\u003e (resistant, multi-resistant, extensively resistant and totally resistant strains). Increasingly frequent infections with non-tuberculous (atypical) strains of mycobacteria causing severe infections of the lungs, bones, digestive system, skin and other soft organs are related to the overall reduced immunity of the human population \u003csup\u003e4\u0026ndash;7\u003c/sup\u003e. In addition to the increased risk of patient death, AMR also results in longer hospital stays and increased healthcare costs \u003csup\u003e4,8,9\u003c/sup\u003e.\u003c/p\u003e \u003cp\u003eIt is understandable that this condition is extremely undesirable in the absence of appropriate treatment and drugs. Currently, various approaches try to overcome the lack of effective drugs. In addition to the application of various synergistic combinations, drug repurposing or nanoparticle (technological) improvements, designing new entities with a new/innovative mechanism of action or with a multi-target effect is considered the most advantageous \u003csup\u003e10\u0026ndash;19\u003c/sup\u003e. This last interesting approach is aimed at the search/design of molecules with multiple mechanisms of action and is used mainly for anti-infective and anticancer drugs, when it is necessary to overcome the resistance \u003csup\u003e20\u003c/sup\u003e. Interestingly, therapeutics active across the species with a so-called dual effect, i.e. with antimicrobial and anticancer or antimicrobial and antiparasitic, etc., can be also found \u003csup\u003e20\u0026ndash;30\u003c/sup\u003e. The search for compounds with dual activity is crucial for developing innovative therapeutics that can address multidrug resistance and complex diseases. Such compounds are identified through various methods, including high-throughput screening of natural products and synthetic libraries, computational drug repurposing, and structure-activity relationship (SAR) studies to optimize their efficacy and selectivity. This approach aligns with the concept of privileged structures, which are molecular frameworks frequently found in bioactive compounds and capable of interacting with multiple biological targets. By focusing on such structural motifs, researchers can enhance the likelihood of discovering dual-acting agents through rational drug design, fragment-based screening, and scaffold-hopping strategies.\u003c/p\u003e \u003cp\u003eAzanaphthalenes, specifically quinolines and especially 8-hydroxyquinolines (8-HQ), are a source of such multi-target agents. It is therefore not surprising that 8-HQs have a wide range of biological properties and can therefore be considered as privileged structures of multi-target agents \u003csup\u003e31\u0026ndash;34\u003c/sup\u003e. The simple 8-HQ scaffold has unique physicochemical properties and affords the possibility of a large number of modifications (via targeted or diversity-directed synthesis) \u003csup\u003e34\u0026ndash;39\u003c/sup\u003e. On the other hand, all these compounds show a mechanism of action that is complex and difficult to determine (e.g. \u003csup\u003e34\u0026ndash;36,38,39\u003c/sup\u003e): they are able to chelate various metals \u003csup\u003e40\u0026ndash;44\u003c/sup\u003e and affect various enzymatic systems \u003csup\u003e34,37,39,45\u0026ndash;49\u003c/sup\u003e. Despite this, quinoline-based compounds form an important scaffold in medicinal chemistry \u003csup\u003e32,34,35,38\u003c/sup\u003e, mainly used for the design of anti-infective \u003csup\u003e35,39,46\u0026ndash;52\u003c/sup\u003e and anticancer agents \u003csup\u003e41,44,45,53\u0026ndash;58\u003c/sup\u003e. It is important to mention that halogenated derivatives of 8-HQ have been approved for their antiseptic use many years ago \u003csup\u003e59\u0026ndash;63\u003c/sup\u003e.\u003c/p\u003e \u003cp\u003eThis contribution is a continuation of the work of our team and deals with the evaluation of antimicrobial (antibacterial, antimycobacterial, antifungal) activity of synthesized ring-substituted 2-styrylquinoline derivatives \u003csup\u003e64\u0026ndash;69\u003c/sup\u003e. The discussed compounds were also tested for their anticancer effect \u003csup\u003e53,54\u003c/sup\u003e, and therefore suitable molecules with only anticancer or anti-infection potential, or with a dual (anticancer\u0026thinsp;+\u0026thinsp;antimicrobial) effect, can be selected from the biologically investigated compounds in this way.\u003c/p\u003e"},{"header":"2. Materials and Methods","content":"\u003cdiv id=\"Sec3\" class=\"Section2\"\u003e \u003ch2\u003e2.1. Compounds\u003c/h2\u003e \u003cp\u003eAll styrylquinoline derivatives investigated in this study were synthesized according to previously reported procedures \u003csup\u003e\u003cspan type=\"Underline\" class=\"Underline\" name=\"Emphasis\"\u003e53\u003c/span\u003e\u003c/sup\u003e. Detailed synthetic protocols, purification methods, and physicochemical characterization data for all new compounds are provided in the Supplementary Material.\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec4\" class=\"Section2\"\u003e \u003ch2\u003e2.2. Biological Studies\u003c/h2\u003e \u003cdiv id=\"Sec5\" class=\"Section3\"\u003e \u003ch2\u003e2.2.1. Test Microorganisms\u003c/h2\u003e \u003cp\u003e \u003cdiv class=\"BlockQuote\"\u003e \u003cp\u003eStandard reference bacterial strains \u003cem\u003eStaphylococcus aureus\u003c/em\u003e ATCC 29213, \u003cem\u003eEnterococcus faecalis\u003c/em\u003e ATCC 2921, \u003cem\u003eMycobacteium tuberculosis\u003c/em\u003e H37Ra/ATCC 25177, \u003cem\u003eMycobacteium smegmatis\u003c/em\u003e ATCC 700084, and \u003cem\u003eMycobacteium kansasii\u003c/em\u003e DSM 44162 were obtained from American Type Culture Collection (ATCC). Clinical isolates of methicillin-resistant \u003cem\u003eS. aureus\u003c/em\u003e SA 3202, SA 630 \u003csup\u003e70\u003c/sup\u003e were obtained from a collection of the National Institute of Public Health, Prague, Czech Republic, and 63718 \u003csup\u003e70\u003c/sup\u003e from a collection of the Department of Infectious Diseases and Microbiology, Faculty of Veterinary Medicine, University of Veterinary Sciences Brno, Czech Republic. \u003cem\u003eCandida albicans\u003c/em\u003e CCM 8261, \u003cem\u003eCandida krusei\u003c/em\u003e CCM 8271, and \u003cem\u003eCandida parapsilosis\u003c/em\u003e CCM 8260 were obtained from a collection of the Czech Collection of Microorganisms, Brno, Czech Republic \u003csup\u003e71\u003c/sup\u003e.\u003c/p\u003e \u003c/div\u003e \u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec6\" class=\"Section3\"\u003e \u003ch2\u003e2.2.2. Determination of Bacterial Minimum Inhibitory Concentration\u003c/h2\u003e \u003cp\u003eMinimum inhibitory concentrations (MICs) were determined using a broth microdilution method in accordance with CLSI guidelines \u003csup\u003e72\u003c/sup\u003e, with minor modifications described previously \u003csup\u003e73\u003c/sup\u003e. Stock solutions of the compounds were prepared in DMSO (10 \u0026micro;g/mL) and further diluted in appropriate media: Cation Adjusted Mueller\u0026ndash;Hinton broth (CaMH, Oxoid) for staphylococci, brain heart infusion (BHI, Oxoid) for enterococci, and Middlebrook 7H9 (Oxoid) for mycobacteria, to obtain final concentrations ranging from 256 to 0.125 \u0026micro;g/mL. Microplates were inoculated with the tested microorganisms. The final inoculum density was 1.5 \u0026times; 10⁶ CFU/mL for \u003cem\u003eM. tuberculosis\u003c/em\u003e and 10⁵ CFU/mL for the remaining bacteria. Ampicillin, ciprofloxacin, and rifampicin (Sigma) were used as reference drugs. Drug-free and sterility controls were included. Plates were incubated under appropriate conditions (24 h at 37\u0026deg;C for staphylococci and enterococci, 3 days for \u003cem\u003eM. smegmatis\u003c/em\u003e, and 14 days for \u003cem\u003eM. tuberculosis\u003c/em\u003e and \u003cem\u003eM. kansasii\u003c/em\u003e). MIC values were defined as the lowest concentration completely inhibiting visible growth. For \u003cem\u003eM. tuberculosis\u003c/em\u003e, MIC determination was performed using the Alamar Blue assay (Oxoid). Following incubation, Alamar Blue reagent (10% v/v) was added, and plates were further incubated for 24 h. The MIC was defined as the lowest concentration preventing the color change from blue (resazurin) to pink (resorufin). All experiments were performed in triplicate.\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec7\" class=\"Section3\"\u003e \u003ch2\u003e2.2.3. MTT Assay\u003c/h2\u003e \u003cp\u003e \u003cdiv class=\"BlockQuote\"\u003e \u003cp\u003eThe MTT assay was performed as previously described \u003csup\u003e74\u0026ndash;77\u003c/sup\u003e, with minor modifications. Compounds were dissolved and diluted in appropriate media (CaMH for staphylococci and Middlebrook 7H9 for mycobacteria) to final concentrations ranging from 256 to 0.0625 \u0026micro;g/mL. Bacterial suspensions were prepared at standard densities and added to microplate wells containing the tested compounds. Control wells without compounds were included, and ciprofloxacin (Sigma) served as a positive control. Samples were prepared in duplicate. After incubation under appropriate conditions (24 h for staphylococci, 3 days for \u003cem\u003eM. smegmatis\u003c/em\u003e, and 14 days for \u003cem\u003eM. tuberculosis\u003c/em\u003e and \u003cem\u003eM. kansasii\u003c/em\u003e), MTT reagent was added to each well (10% v/v), followed by further incubation to allow formazan formation. The reaction was stopped by addition of sodium dodecyl sulfate solution, and absorbance was measured at 570 nm. Cell viability was expressed as a percentage relative to untreated controls using the ratio of absorbance values. A reduction in viability below 70% was considered indicative of cytotoxic activity. The results are presented in Tables\u0026nbsp;\u003cspan refid=\"Tab2\" class=\"InternalRef\"\u003e2\u003c/span\u003e and \u003cspan refid=\"Tab3\" class=\"InternalRef\"\u003e3\u003c/span\u003e.\u003c/p\u003e \u003c/div\u003e \u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec8\" class=\"Section3\"\u003e \u003ch2\u003e2.2.4. Determination of Minimum Fungistatic Activity\u003c/h2\u003e \u003cp\u003e \u003cdiv class=\"BlockQuote\"\u003e \u003cp\u003eThe minimum fungistatic inhibitory concentrations were evaluated by the microdilution broth method according to the CLSI \u003csup\u003e78\u003c/sup\u003e with some modifications as described previously \u003csup\u003e73\u003c/sup\u003e. The compounds were dissolved in DMSO (Sigma) to get concentration 10 \u0026micro;g/mL and diluted in RPMI-1640 medium (Sigma) to concentrations of 256\u0026ndash;1 \u0026micro;g/mL. To prepare fungal inoculum in RPMI-1640 broth, the microorganisms were grown on Sabourad dextrose agar (Sigma) at 37\u0026deg;C for 24 h (\u003cem\u003eC. albicans\u003c/em\u003e, C. \u003cem\u003ekrusei\u003c/em\u003e) and for 48 h (\u003cem\u003eC. parapsilosis\u003c/em\u003e). The plate was then inoculated with a pipette, the final concentration of fungal cells was 5\u0026times;10\u003csup\u003e2\u003c/sup\u003e CFU/mL in each well. The plate was incubated in 37\u0026deg;C for 24 h or 48 h. After incubation the minimal fungistatic concentration was evaluated as a minimal concentration of tested compounds, which visibly inhibited the fungal growth.\u003c/p\u003e \u003c/div\u003e \u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec9\" class=\"Section3\"\u003e \u003ch2\u003e2.2.5. Cell Viability Assay\u003c/h2\u003e \u003cp\u003eThe human colorectal carcinoma cell line HCT 116 with wild type of p53 (p53\u003csup\u003e+/+\u003c/sup\u003e) were obtained from the ATCC. HCT 116 with deletion of TP53 gene (p53\u003csup\u003e\u0026minus;/\u0026minus;\u003c/sup\u003e) was provided from Maria Sklodowska-Curie Memorial Cancer Center and Institute of Oncology in Gliwice, Poland. The normal human dermal fibroblast cell line (NHDF) was purchased from PromoCell (Heidelberg, Germany). A recently described procedure \u003csup\u003e53\u003c/sup\u003e was used. The results are shown in Table\u0026nbsp;\u003cspan refid=\"Tab1\" class=\"InternalRef\"\u003e1\u003c/span\u003e.\u003c/p\u003e \u003c/div\u003e \u003c/div\u003e"},{"header":"3. Results and Discussion","content":"\u003cdiv id=\"Sec11\" class=\"Section2\"\u003e \u003ch2\u003e3.1. Chemistry\u003c/h2\u003e \u003cp\u003eThe investigated styrylquinoline derivatives were synthesized using commercially available quinaldines I\u0026ndash;III as starting materials. The synthetic route involved an initial condensation step with appropriate aromatic aldehydes (Scheme \u003cspan refid=\"Sch1\" class=\"InternalRef\"\u003e1\u003c/span\u003e), performed in a boiling mixture of acetic anhydride and 80% acetic acid (3:1, v/v). Under these conditions, all hydroxyl groups present in the substrates underwent acylation, requiring a subsequent deprotection step to regenerate the corresponding hydroxyl functionalities.\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003cp\u003eSelective removal of acetyl groups was achieved using either pyridine/water or potassium carbonate in methanol (Scheme \u003cspan refid=\"Sch2\" class=\"InternalRef\"\u003e2\u003c/span\u003e). Treatment with pyridine/water resulted in preferential deacylation of the hydroxyl group substituted with the quinoline moiety, while the acetyl group on the phenyl ring remained intact. In contrast, the use of potassium carbonate in methanol at room temperature enabled complete deprotection of all hydroxyl groups. These approaches allowed for controlled and selective deacylation of styrylquinoline derivatives depending on the reaction conditions.\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003cp\u003eSixty-four compounds were prepared in this way, of which 59 have been previously reported, see \u003csup\u003e53,54\u003c/sup\u003e. Derivatives \u003cb\u003eD8\u003c/b\u003e, \u003cb\u003eD11\u003c/b\u003e, \u003cb\u003eD12\u003c/b\u003e, \u003cb\u003eD13\u003c/b\u003e and \u003cb\u003eE2\u003c/b\u003e are novel, have not been described in the literature, and their characteristics are listed in the Supplementary Material. All the discussed compounds were classified into 5 groups according to their structure: \u003cb\u003eA1\u003c/b\u003e\u0026ndash;\u003cb\u003e15\u003c/b\u003e (2-[(\u003cem\u003eE\u003c/em\u003e)-2-arylethenyl]quinolin-8-yl acetates), \u003cb\u003eB1\u003c/b\u003e\u0026ndash;\u003cb\u003e7\u003c/b\u003e (2-[(\u003cem\u003eE\u003c/em\u003e)-2-arylethenyl]quinolin-8-ols), \u003cb\u003eC1\u003c/b\u003e\u0026ndash;\u003cb\u003e23\u003c/b\u003e (5,7-dichloro-2-[(\u003cem\u003eE\u003c/em\u003e)-2-arylethenyl]quinolin-8-yl acetates), \u003cb\u003eD1\u003c/b\u003e\u0026ndash;\u003cb\u003e15\u003c/b\u003e (5,7-dichloro-2-[(\u003cem\u003eE\u003c/em\u003e)-2-arylethenyl]quinolin-8-ols), \u003cb\u003eE1\u003c/b\u003e\u0026ndash;\u003cb\u003e4\u003c/b\u003e (2-[(\u003cem\u003eE\u003c/em\u003e)-2-arylethenyl]quinolin-4-ols). Their structures and individual substitutions are presented in Table\u0026nbsp;\u003cspan refid=\"Tab1\" class=\"InternalRef\"\u003e1\u003c/span\u003e.\u003c/p\u003e \u003cp\u003eSince lipophilicity is a key parameter affecting the fate of all bioactive agents \u003csup\u003e79,80\u003c/sup\u003e and influencing their activity \u003csup\u003e81\u003c/sup\u003e, lipophilicity values expressed as log \u003cem\u003eP\u003c/em\u003e were estimated for all compounds, see Table\u0026nbsp;\u003cspan refid=\"Tab1\" class=\"InternalRef\"\u003e1\u003c/span\u003e. Log \u003cem\u003eP\u003c/em\u003e values were calculated using ACD/Percepta ver. 2012 (Advanced Chemistry Development. Inc., Toronto, ON, Canada, 2012).\u003c/p\u003e \u003cp\u003eCompounds of series A exhibited log \u003cem\u003eP\u003c/em\u003e values in the range from 3.51 to 5.22, their deacetylated derivatives of series B had log \u003cem\u003eP\u003c/em\u003e value in the range 3.35\u0026ndash;5.04. 5,7-Dichlorinated derivatives of series C had log \u003cem\u003eP\u003c/em\u003e ranging from 5.10 to 7.11; while the range of log \u003cem\u003eP\u003c/em\u003e values of series D was 5.33\u0026ndash;7.04. Compounds of series E had log \u003cem\u003eP\u003c/em\u003e values in the range from 3.73 to 5.53. Thus it can be concluded that all the investigated derivatives are rather lipophilic substances. In general, (\u003cem\u003eE\u003c/em\u003e)-2-[2-(2-acetoxyphenyl)vinyl]quinolin-8-ol (\u003cb\u003eB2\u003c/b\u003e) is the least lipophilic (log \u003cem\u003eP\u003c/em\u003e\u0026thinsp;=\u0026thinsp;3.35), while (\u003cem\u003eE\u003c/em\u003e)-5,7-dichloro-2-[2-(2-acetoxy-3,5-dichlorophenyl)vinyl]quinolin-8-yl acetate (\u003cb\u003eC20\u003c/b\u003e) is the most lipophilic (log \u003cem\u003eP\u003c/em\u003e\u0026thinsp;=\u0026thinsp;7.11) of all the discussed compounds. It can be assumed that lipophilicities increase in the series B\u0026thinsp;\u0026lt;\u0026thinsp;A \u0026lt; D\u0026thinsp;\u0026lt;\u0026thinsp;C. But this only applies to halogen-type substitutions on styryl. If NO\u003csub\u003e2\u003c/sub\u003e or CN is used as substituents, a change in order can be traced and the prediction software assigns the C-series compounds higher lipophilicity than the D-series compounds (\u003cb\u003eC1\u003c/b\u003e\u0026ndash;\u003cb\u003e6\u003c/b\u003e\u0026thinsp;\u0026lt;\u0026thinsp;\u003cb\u003eD1\u003c/b\u003e\u0026ndash;\u003cb\u003e6\u003c/b\u003e) probably due to intramolecular interactions. The compounds of group E appear to have log \u003cem\u003eP\u003c/em\u003e values between those of groups A and D.\u003c/p\u003e \u003cp\u003eIn addition, the electronic σ parameters illustrating the effect of substituents of the phenyl ring of styryl tail were predicted. These σ parameters are in a wide range from 0.01 (2-OEt), i.e., rather with the properties of donating electrons to the system, up to ~\u0026thinsp;1.6 (2,6-F-3-Cl, 2,4-NO\u003csub\u003e2\u003c/sub\u003e), i.e., with a very strong electron-withdrawing effect. Also, these σ parameters were predicted using ACD/Percepta ver. 2012.\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec12\" class=\"Section2\"\u003e \u003ch2\u003e3.2. Biology\u003c/h2\u003e \u003cp\u003eAs mentioned above, most of the compounds have been previously described when their anticancer potential was investigated \u003csup\u003e53,54\u003c/sup\u003e. By comparing the IC\u003csub\u003e50\u003c/sub\u003e values obtained against colon cancer cell lines HCT 116 p53\u003csup\u003e+/+\u003c/sup\u003e and HCT 116 p53\u003csup\u003e\u0026minus;/\u0026minus;\u003c/sup\u003e versus normal human dermal fibroblasts (NHDF), their possible therapeutic potential can be seen. Five new compounds were also tested on these human cell lines and all IC\u003csub\u003e50\u003c/sub\u003e values are shown in Table\u0026nbsp;\u003cspan refid=\"Tab1\" class=\"InternalRef\"\u003e1\u003c/span\u003e. Considering the previous positive antimicrobial results of selected styrylquinoline derivatives \u003csup\u003e47,64\u0026ndash;68,82\u003c/sup\u003e, all the discussed derivatives were subjected to extensive in vitro screening against Gram-positive bacteria, mycobacteria, and candida.\u003c/p\u003e \u003cp\u003eFirst, universally susceptible collection strains of \u003cem\u003eStaphylococcus aureus\u003c/em\u003e ATCC 29213 and \u003cem\u003eEnterococcus faecalis\u003c/em\u003e ATCC 29212 were selected. Some of the compounds were effective against \u003cem\u003eS. aureus\u003c/em\u003e, so testing continued on staphylococcal strains with an epidemiologically significant type of resistance; clinical isolates of methicillin-resistant \u003cem\u003eStaphylococcus aureus\u003c/em\u003e (MRSA) of human and veterinary origin (SA 3202, SA 630, 63718) carrying the \u003cem\u003emecA\u003c/em\u003e gene were selected \u003csup\u003e70\u003c/sup\u003e. Unfortunately, none of the compounds showed activity against facultatively anaerobic \u003cem\u003eE. faecalis\u003c/em\u003e, so other similar types of bacteria or resistant isolates of \u003cem\u003eE. faecalis\u003c/em\u003e were not tested. All the compounds were also in vitro tested against \u003cem\u003eMycobacteium tuberculosis\u003c/em\u003e H37Ra/ATCC 25177 and additionally against \u003cem\u003eMycobacterium smegmatis\u003c/em\u003e ATCC 700084 and \u003cem\u003eMycobacterium kansasii\u003c/em\u003e DSM 44162 as representatives of non-tuberculous mycobacteria causing increasingly frequent and difficult-to-treat mycobacterial infections, especially in immunocompromised patients \u003csup\u003e7\u003c/sup\u003e. \u003cem\u003eM. tuberculosis\u003c/em\u003e and \u003cem\u003eM. kansasii\u003c/em\u003e are slow-growing mycobacteria, while \u003cem\u003eM. smegmatis\u003c/em\u003e is a fast-growing strain. In addition, all the compounds were \u003cem\u003ein vitro\u003c/em\u003e tested against three representatives of yeasts: \u003cem\u003eCandida albicans\u003c/em\u003e CCM 8361, \u003cem\u003eCandida krusei\u003c/em\u003e CCM 8271, \u003cem\u003eCandida parapsilosis\u003c/em\u003e CCM 8260. Activities are expressed as the minimum inhibitory concentrations (MICs); see Table\u0026nbsp;\u003cspan refid=\"Tab1\" class=\"InternalRef\"\u003e1\u003c/span\u003e.\u003c/p\u003e \u003cp\u003eLooking at the results from Table\u0026nbsp;\u003cspan refid=\"Tab1\" class=\"InternalRef\"\u003e1\u003c/span\u003e and comparing the MIC values of the discussed compounds with their antiproliferative values against cancer cells, it can be stated that the compounds showed greater anticancer activity for which they were primarily designed. Of the 64 compounds, only 20 derivatives showed remarkable antimicrobial activity.\u003c/p\u003e \u003cp\u003eFrom series A, compounds \u003cb\u003eA2\u003c/b\u003e (R\u0026thinsp;=\u0026thinsp;3-OMe, log \u003cem\u003eP\u003c/em\u003e\u0026thinsp;=\u0026thinsp;4.02, σ\u0026thinsp;=\u0026thinsp;0.66) and \u003cb\u003eA7\u003c/b\u003e (R\u0026thinsp;=\u0026thinsp;2-Cl, log \u003cem\u003eP\u003c/em\u003e\u0026thinsp;=\u0026thinsp;4.46, σ\u0026thinsp;=\u0026thinsp;1.05) were selective against mycobacteria, and derivative \u003cb\u003eA9\u003c/b\u003e (R\u0026thinsp;=\u0026thinsp;2-NO\u003csub\u003e2\u003c/sub\u003e, log \u003cem\u003eP\u003c/em\u003e\u0026thinsp;=\u0026thinsp;3.78, σ\u0026thinsp;=\u0026thinsp;1.12) selective against \u003cem\u003eCandida\u003c/em\u003e sp. On the other hand, agent \u003cb\u003eA13\u003c/b\u003e (R\u0026thinsp;=\u0026thinsp;2,6-Cl, log \u003cem\u003eP\u003c/em\u003e\u0026thinsp;=\u0026thinsp;5.20, σ\u0026thinsp;=\u0026thinsp;1.33) was effective in the entire spectrum of tested microorganisms (except \u003cem\u003eE. faecalis\u003c/em\u003e). All compounds showed insignificant effect against normal human fibroblasts (NHDF). From series B, compound \u003cb\u003eB4\u003c/b\u003e (R\u0026thinsp;=\u0026thinsp;2-NO\u003csub\u003e2\u003c/sub\u003e, log \u003cem\u003eP\u003c/em\u003e\u0026thinsp;=\u0026thinsp;3.64, σ\u0026thinsp;=\u0026thinsp;1.12) was selective against \u003cem\u003eCandida\u003c/em\u003e sp. (similar to series A) and derivative \u003cb\u003eB5\u003c/b\u003e (R\u0026thinsp;=\u0026thinsp;3,5-OMe, log \u003cem\u003eP\u003c/em\u003e\u0026thinsp;=\u0026thinsp;3.93, σ\u0026thinsp;=\u0026thinsp;0.93) showed selective antistaphylococcal activity. Similar to series A, agent \u003cb\u003eB6\u003c/b\u003e (R\u0026thinsp;=\u0026thinsp;2,6-Cl, log \u003cem\u003eP\u003c/em\u003e\u0026thinsp;=\u0026thinsp;5.04, σ\u0026thinsp;=\u0026thinsp;1.33) was effective across the tested spectrum. All compounds also showed negligible activity against NHDF.\u003c/p\u003e \u003cp\u003eBy comparing the antimicrobial activities and physicochemical parameters of compounds from series A and B, it can be concluded that lipophilicity does not play a fundamental role in the activity, electronic parameters partially influence the activity (a higher value of σ is advantageous), but the nature and position of the substituents on the phenyl ring of styryl are most significant for the activity (compare the effects of \u003cb\u003eA12\u003c/b\u003e, \u003cb\u003eA13\u003c/b\u003e, \u003cb\u003eA14\u003c/b\u003e). It can be assumed that the hydroxyl group of the quinoline ring is advantageous for activity against staphylococci, compared the activity of \u003cb\u003eA11\u003c/b\u003e/\u003cb\u003eB5\u003c/b\u003e (R\u0026thinsp;=\u0026thinsp;3,5-OMe), as described e.g., \u003csup\u003e64,68,83\u003c/sup\u003e. On the other hand, deacetylation of the C\u003csub\u003e8\u003c/sub\u003e-hydroxylic group did not affect the activity when styryl was substituted with 2-NO\u003csub\u003e2\u003c/sub\u003e or 2,6-Cl (comparable activity of acetylated/deacetylated compounds \u003cb\u003eA9\u003c/b\u003e/\u003cb\u003eB4\u003c/b\u003e, \u003cb\u003eA13\u003c/b\u003e/\u003cb\u003eB6\u003c/b\u003e).\u003c/p\u003e \u003cp\u003eWithin series C, compounds \u003cb\u003eC1\u003c/b\u003e (R\u0026thinsp;=\u0026thinsp;2-Cl, log \u003cem\u003eP\u003c/em\u003e 6.17, σ\u0026thinsp;=\u0026thinsp;1.05) and \u003cb\u003eC5\u003c/b\u003e (R\u0026thinsp;=\u0026thinsp;4-CN, log \u003cem\u003eP\u003c/em\u003e 5.39, σ\u0026thinsp;=\u0026thinsp;1.05) were selective against mycobacteria, while derivative \u003cb\u003eC3\u003c/b\u003e (R\u0026thinsp;=\u0026thinsp;2-CN, log \u003cem\u003eP\u003c/em\u003e 6.17, σ\u0026thinsp;=\u0026thinsp;1.04) showed selective antistaphylococcal activity. On the other hand, compound \u003cb\u003eC6\u003c/b\u003e (R\u0026thinsp;=\u0026thinsp;2-NO\u003csub\u003e2\u003c/sub\u003e, log \u003cem\u003eP\u003c/em\u003e\u0026thinsp;=\u0026thinsp;5.27, σ\u0026thinsp;=\u0026thinsp;1.12), probably due to chlorination of the quinoline ring nucleus, extended the activity from anticandidal to antistaphylococcal activity as well (as described e.g., by \u003csup\u003e84,85\u003c/sup\u003e. Traditionally, agent \u003cb\u003eC11\u003c/b\u003e (R\u0026thinsp;=\u0026thinsp;2,6-Cl, log \u003cem\u003eP\u003c/em\u003e\u0026thinsp;=\u0026thinsp;7.10, σ\u0026thinsp;=\u0026thinsp;1.33) was the most potent derivative against the entire spectrum of microorganisms. As a result of the chlorination of 8-acetoxyquinoline (8-AcQ) (and thus higher lipophilicity), there was also an increase in activity compared to derivative \u003cb\u003eA13\u003c/b\u003e. The increase in antimicrobial activity associated with higher lipophilicity (chlorination of 8-AcQ) is also associated with higher antiproliferative activity not only against HCT 116 cancer cell lines but also against NHDF cells (\u003cb\u003eC11\u003c/b\u003e had an IC\u003csub\u003e50\u003c/sub\u003e\u0026thinsp;=\u0026thinsp;9.55 \u0026micro;M on NHDF).\u003c/p\u003e \u003cp\u003eGroup D showed the highest amount of active substances. In general, halogenation of 8-HQ, i.e. higher lipophilicity leads to higher potency and subsequent deacetylation (release) of the quinoline hydroxyl group further increases activity. Importantly, there was no undesirable increase in antiproliferative activity against NHDF as in the case of the acetylated series C, although the most successful 2,6-Cl styryl substitution (compound \u003cb\u003eD8\u003c/b\u003e) showing the highest activity against the tested microorganisms showed comparable adverse effects against NHDF (IC\u003csub\u003e50\u003c/sub\u003e\u0026thinsp;=\u0026thinsp;6.22 \u0026micro;M) along with \u003cb\u003eC11\u003c/b\u003e; other derivatives showed an insignificant effect on NHDF cells. As in the previous case with series C, compounds \u003cb\u003eD1\u003c/b\u003e (R\u0026thinsp;=\u0026thinsp;2-CN, log \u003cem\u003eP\u003c/em\u003e\u0026thinsp;=\u0026thinsp;5.65, σ\u0026thinsp;=\u0026thinsp;1.04) demonstrated selective antistaphylococcal activity and \u003cb\u003eD3\u003c/b\u003e (R\u0026thinsp;=\u0026thinsp;4-CN, log \u003cem\u003eP\u003c/em\u003e\u0026thinsp;=\u0026thinsp;5.71, σ\u0026thinsp;=\u0026thinsp;1.05) selective antimycobacterial activity. In the case of derivative \u003cb\u003eD4\u003c/b\u003e (R\u0026thinsp;=\u0026thinsp;2-NO\u003csub\u003e2\u003c/sub\u003e, log \u003cem\u003eP\u003c/em\u003e\u0026thinsp;=\u0026thinsp;5.45, σ\u0026thinsp;=\u0026thinsp;1.12), in comparison with the series A, B and C, not only was the activity strengthened, but also its expansion from the original anticandidal to antistaphylococcal and finally to antimycobacterial efficacy. After hydrolysis of the acyl group in the 8-position of the quinoline ring, derivative \u003cb\u003eD10\u003c/b\u003e (R\u0026thinsp;=\u0026thinsp;2,4-NO2, log P\u0026thinsp;=\u0026thinsp;5.33, σ\u0026thinsp;=\u0026thinsp;1.66) was activated, which was completely inactive in the series A and C. Along with the above-mentioned changes on the quinoline core, new derivatives were activated: \u003cb\u003eD11\u003c/b\u003e (R\u0026thinsp;=\u0026thinsp;2-OH-5-Cl, log \u003cem\u003eP\u003c/em\u003e\u0026thinsp;=\u0026thinsp;6.25, σ\u0026thinsp;=\u0026thinsp;1.04) acquired anticandidal and antimycobacterial activity, \u003cb\u003eD13\u003c/b\u003e (R\u0026thinsp;=\u0026thinsp;2-OH-5-NO\u003csub\u003e2\u003c/sub\u003e, log \u003cem\u003eP\u003c/em\u003e\u0026thinsp;=\u0026thinsp;5.68, σ\u0026thinsp;=\u0026thinsp;1.28) acquired antistaphylococcal and antimycobacterial and especially \u003cb\u003eD12\u003c/b\u003e (R\u0026thinsp;=\u0026thinsp;2-OAc-5-Cl, log \u003cem\u003eP\u003c/em\u003e\u0026thinsp;=\u0026thinsp;6.18, σ\u0026thinsp;=\u0026thinsp;0.18) obtained an effect against the entire spectrum of microorganisms.\u003c/p\u003e \u003cp\u003eThe last and smallest series E, where the hydroxylic group from position 8 of the quinoline was moved to position 4, were completely inactive.\u003c/p\u003e \u003cp\u003e5,7-Dichloro-8-hydroxyquinoline derivatives (series D) exhibit the broadest spectrum of biological activity among the tested compounds. The most potent agents are those bearing a 2,6-dichloro substitution in the styryl tail (compounds \u003cb\u003eC11\u003c/b\u003e and \u003cb\u003eD8\u003c/b\u003e). However, these derivatives also demonstrate relatively high toxicity toward normal human NHDF cells. Consequently, the optimal balance between antimicrobial efficacy and safety appears to be achieved by derivatives \u003cb\u003eD4\u003c/b\u003e (featuring a 2-NO₂ group) and \u003cb\u003eD10\u003c/b\u003e (bearing 2,4-NO₂ groups). In addition to their antimicrobial properties, both \u003cb\u003eD4\u003c/b\u003e and \u003cb\u003eD10\u003c/b\u003e show excellent antitumor activity, with IC₅₀ values ranging from 0.54 to 0.76 \u0026micro;M (Fig.\u0026nbsp;\u003cspan refid=\"Fig1\" class=\"InternalRef\"\u003e1\u003c/span\u003e). It is also worth noting that despite the very low MIC values achieved by some standard drugs (e.g. CPX, RIF), the tested compounds exhibit unique properties \u0026ndash; not only strong activity against SA strains, but also an extended spectrum of activity including MRSA strains, mycobacterial pathogens (MT, MS, MK) and Candida fungi. Differences in activity against individual microorganisms may result from interactions specific to the structure of cell walls and mechanisms of penetration through the lipid barrier, which opens new perspectives in the design of drugs with a broad spectrum of action.\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003cp\u003eSince the compounds exhibit activity against aerobic staphylococci but not against facultatively anaerobic enterococci \u003csup\u003e86\u0026ndash;89\u003c/sup\u003e, suggested that their mechanism of action may be associated with interference in respiratory processes \u003csup\u003e90\u003c/sup\u003e. To verify this hypothesis, an MTT assay was performed for the most active derivatives. This assay enables indirect evaluation of bacterial viability through measurement of metabolic activity. A decrease in respiratory activity below 70% of the control level after exposure to MIC concentrations was considered indicative of a positive effect. Such reduction in oxidative metabolism reflects impaired cellular function and suggests involvement of respiration-related mechanisms \u003csup\u003e74,77\u003c/sup\u003e.\u003c/p\u003e \u003cp\u003eThe lowest MIC multiples required to achieve\u0026thinsp;\u0026gt;\u0026thinsp;70% reduction in viability of \u003cem\u003eS. aureus\u003c/em\u003e ATCC 29213 and MRSA isolate SA 3202 are presented in Table\u0026nbsp;\u003cspan refid=\"Tab2\" class=\"InternalRef\"\u003e2\u003c/span\u003e. Compounds \u003cb\u003eA13/B6/C11/D8\u003c/b\u003e (R\u0026thinsp;=\u0026thinsp;2,6-Cl) and \u003cb\u003eD12\u003c/b\u003e (R\u0026thinsp;=\u0026thinsp;2-OAc-5-Cl) did not show any significant inhibition in the MTT assay, even at the highest tested concentration (256 \u0026micro;g/mL). In contrast, compounds \u003cb\u003eD1\u003c/b\u003e (R\u0026thinsp;=\u0026thinsp;2-CN), \u003cb\u003eD10\u003c/b\u003e (R\u0026thinsp;=\u0026thinsp;2,4-NO2), and \u003cb\u003eD13\u003c/b\u003e (R\u0026thinsp;=\u0026thinsp;2-OH-5-NO2) exhibited only limited inhibition at elevated MIC values. These results indicate that, despite pronounced antibacterial activity against staphylococci, the tested styrylquinoline derivatives do not primarily affect cellular respiration and may act via alternative mechanisms. Notably, comparable activity was observed against both methicillin-susceptible \u003cem\u003eS. aureus\u003c/em\u003e and MRSA strains, suggesting that the presence of the mecA gene, responsible for methicillin resistance \u003csup\u003e70,91\u003c/sup\u003e, does not influence the efficacy of these compounds. This supports the hypothesis of a distinct mode of action specific to \u003cem\u003eStaphylococcus\u003c/em\u003e spp.\u003c/p\u003e \u003cp\u003e \u003cdiv class=\"gridtable\"\u003e\u003ctable float=\"Yes\" id=\"Tab2\" border=\"1\"\u003e \u003ccaption language=\"En\"\u003e \u003cdiv class=\"CaptionNumber\"\u003eTable 2\u003c/div\u003e \u003cdiv class=\"CaptionContent\"\u003e \u003cp\u003eLowest MIC values with at least 70% inhibition of respiratory activity of staphylococcal strains.\u003c/p\u003e \u003c/div\u003e \u003c/caption\u003e \u003ccolgroup cols=\"3\"\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c1\" colnum=\"1\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c2\" colnum=\"2\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c3\" colnum=\"3\"\u003e\u003c/div\u003e \u003cthead\u003e \u003ctr\u003e \u003cth align=\"left\" colname=\"c1\"\u003e \u003cp\u003eNo.\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c2\"\u003e \u003cp\u003eSA resp. inh. (Conc.)\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c3\"\u003e \u003cp\u003eMRSA1 resp. inh. (Conc.)\u003c/p\u003e \u003c/th\u003e \u003c/tr\u003e \u003c/thead\u003e \u003ctbody\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cb\u003eD1\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e96.6% (8\u0026times; MIC)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e92.6% (2\u0026times; MIC)\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cb\u003eD10\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e96.6% (4\u0026times; MIC)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e84.5% (8\u0026times; MIC)\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cb\u003eD13\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e80.6% (32\u0026times; MIC)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e83.1% (32\u0026times; MIC)\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cb\u003eCPX\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e92.5% (32\u0026times; MIC)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e96.5% (32\u0026times; MIC)\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003c/tbody\u003e \u003c/colgroup\u003e \u003ctfoot\u003e \u003ctr\u003e\u003ctd colspan=\"3\"\u003eSA\u0026thinsp;=\u0026thinsp;\u003cem\u003eStaphyloccoccus aureus\u003c/em\u003e ATCC 29213; MRSA1\u0026thinsp;\u003cem\u003e=\u003c/em\u003e\u0026thinsp;clinical isolate of methicillin-resistant \u003cem\u003eS. aureus\u003c/em\u003e SA 3202; CPX\u0026thinsp;=\u0026thinsp;ciprofloxacin\u003c/td\u003e\u003c/tr\u003e \u003c/tfoot\u003e \u003c/table\u003e\u003c/div\u003e \u003c/p\u003e \u003cp\u003eQuinoline derivatives are known to exhibit antimycobacterial activity, which is often associated with inhibition of mycobacterial ATP synthase and disruption of cellular respiration \u003csup\u003e\u003cem\u003e48,92,93\u003c/em\u003e\u003c/sup\u003e. Therefore, in addition to MIC determination, an MTT assay was performed for the most active compounds. Similarly to the previous analysis, a reduction in respiratory activity of mycobacterial cells below 70% of the control after exposure to MIC concentrations was considered indicative of a positive result \u003csup\u003e\u003cem\u003e74\u0026ndash;76\u003c/em\u003e\u003c/sup\u003e. The lowest MIC multiples required to achieve more than 70% inhibition of mycobacterial viability are summarized in Table\u0026nbsp;\u003cspan refid=\"Tab3\" class=\"InternalRef\"\u003e3\u003c/span\u003e. Compound \u003cb\u003eA7\u003c/b\u003e (R\u0026thinsp;=\u0026thinsp;2-Cl) showed inhibition of respiration at 1\u0026times; MIC across all tested mycobacterial species. In contrast, disubstituted derivatives \u003cb\u003eA13/B6/C11/D8\u003c/b\u003e (R\u0026thinsp;=\u0026thinsp;2,6-Cl) did not exhibit any detectable MTT inhibition, even at the highest tested concentration (256 \u0026micro;g/mL), similarly to the observations for staphylococci. On the other hand, the remaining highly active compounds (\u003cb\u003eC5\u003c/b\u003e, \u003cb\u003eD1\u003c/b\u003e, \u003cb\u003eD10\u003c/b\u003e, \u003cb\u003eD13\u003c/b\u003e) demonstrated pronounced inhibition of the mycobacterial respiratory chain not only at MIC values but also at sub-MIC concentrations, in some cases as low as one-sixteenth of the MIC (e.g., \u003cb\u003eC5/D1\u003c/b\u003e, R\u0026thinsp;=\u0026thinsp;4-CN, against \u003cem\u003eM. smegmatis\u003c/em\u003e). These findings suggest that derivatives bearing 2,6-dichloro substitution may act via a mechanism distinct from other active styrylquinoline derivatives.\u003c/p\u003e \u003cp\u003e \u003cdiv class=\"gridtable\"\u003e\u003ctable float=\"Yes\" id=\"Tab3\" border=\"1\"\u003e \u003ccaption language=\"En\"\u003e \u003cdiv class=\"CaptionNumber\"\u003eTable 3\u003c/div\u003e \u003cdiv class=\"CaptionContent\"\u003e \u003cp\u003eLowest MIC values with at least 70% inhibition of respiratory activity of mycobacterial strains.\u003c/p\u003e \u003c/div\u003e \u003c/caption\u003e \u003ccolgroup cols=\"4\"\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c1\" colnum=\"1\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c2\" colnum=\"2\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c3\" colnum=\"3\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c4\" colnum=\"4\"\u003e\u003c/div\u003e \u003cthead\u003e \u003ctr\u003e \u003cth align=\"left\" colname=\"c1\"\u003e \u003cp\u003eNo.\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c2\"\u003e \u003cp\u003eMT resp. inh. (Conc.)\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c3\"\u003e \u003cp\u003eMS resp. inh. (Conc.)\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c4\"\u003e \u003cp\u003eMK resp. inh. (Conc.)\u003c/p\u003e \u003c/th\u003e \u003c/tr\u003e \u003c/thead\u003e \u003ctbody\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cb\u003eA7\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e75.3% (1\u0026times; MIC)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e91.0% (1\u0026times; MIC\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e87.5% (0.5\u0026times; MIC\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cb\u003eC5\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e89.5% (0.5\u0026times; MIC)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e90.6% (0.063\u0026times; MIC)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e90.9% (0.5\u0026times; MIC)\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cb\u003eD1\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e92.8% (0.5\u0026times; MIC)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e92.3% (0.063\u0026times; MIC)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e91.4% (0.5\u0026times; MIC)\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cb\u003eD10\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e94.4% (1\u0026times; MIC)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e86.8% (1\u0026times; MIC)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e92.3% (0.5\u0026times; MIC)\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cb\u003eD13\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e87.5% (1\u0026times; MIC)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e88.0% (1\u0026times; MIC)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e87.7% (1\u0026times; MIC)\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cb\u003eCPX\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e95.2% (32\u0026times; MIC)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e94.7% (64\u0026times; MIC)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e95.0% (64\u0026times; MIC)\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003c/tbody\u003e \u003c/colgroup\u003e \u003ctfoot\u003e \u003ctr\u003e\u003ctd colspan=\"4\"\u003eMT\u0026thinsp;\u003cem\u003e=\u0026thinsp;Mycobacteium tuberculosis\u003c/em\u003e H37Ra/ATCC 25177; MS\u0026thinsp;=\u0026thinsp;\u003cem\u003eMycobacteium smegmatis\u003c/em\u003e ATCC 700084, MK\u0026thinsp;=\u0026thinsp;\u003cem\u003eMycobacteium kansasii\u003c/em\u003e DSM 44162; CPX\u0026thinsp;=\u0026thinsp;ciprofloxacin\u003c/td\u003e\u003c/tr\u003e \u003c/tfoot\u003e \u003c/table\u003e\u003c/div\u003e \u003c/p\u003e \u003cp\u003eThis extensive antimicrobial screening succeeded in finding new multi-target \u003cem\u003eagents\u003c/em\u003e with very good activity against a wide spectrum of microorganisms and a good safety profile. Either these are substances with a selective effect against mycobacteria (\u003cb\u003eA2\u003c/b\u003e, \u003cb\u003eA7\u003c/b\u003e, \u003cb\u003eC1\u003c/b\u003e), staphylococci (\u003cb\u003eB5\u003c/b\u003e, \u003cb\u003eC3\u003c/b\u003e, \u003cb\u003eD1\u003c/b\u003e) or candida (\u003cb\u003eA9\u003c/b\u003e, \u003cb\u003eB4\u003c/b\u003e) or, on the contrary, they are compounds with a broad spectrum of antimicrobial effect (\u003cb\u003eA13\u003c/b\u003e, \u003cb\u003eB6\u003c/b\u003e, \u003cb\u003eD4\u003c/b\u003e, \u003cb\u003eD10\u003c/b\u003e, \u003cb\u003eD11\u003c/b\u003e, \u003cb\u003eD12\u003c/b\u003e, \u003cb\u003eD13\u003c/b\u003e). Most of these compounds simultaneously demonstrated dual activity against colon cancer cell lines.\u003c/p\u003e \u003c/div\u003e"},{"header":"4. Conclusion","content":"\u003cp\u003eSeveral compounds from a series of sixty-four ring-substituted 2-styrylquinolines tested against Gram-positive bacteria, slow- and fast-growing mycobacteria, and \u003cem\u003eCandida\u003c/em\u003e sp. expressed activity comparable to or higher than clinically used drugs. Antimicrobial active compounds have also shown activity against colon cancer cell lines. Chlorination of the quinoline nucleus and the unsubstituted phenolic moiety at position 8 of quinoline positively affects antimicrobial activity. The crucial factor influencing the activity is not the lipophilicity itself or the electron-withdrawing properties of the styryl tail, but the type of substituent and, especially, the position of the substituents on the styryl. Positions C\u003csub\u003e2,6\u003c/sub\u003e' substituted with chlorine, C\u003csub\u003e2\u003c/sub\u003e'/C\u003csub\u003e2,4\u003c/sub\u003e' substituted with a nitro group are preferred. It has been shown that the compounds do not affect cellular respiration in staphylococci, on the other hand, they significantly inhibit cellular respiration in mycobacteria. Thus, this primary screening revealed promising multi-target agents with dual (antimicrobial+ anticancer) activity and insignificantly affecting non-cancerous human cells.\u003c/p\u003e"},{"header":"Declarations","content":"\u003cp\u003e \u003ch2\u003eDeclarations of interest\u003c/h2\u003e \u003cp\u003eThe authors declare no competing financial or non-financial interests.\u003c/p\u003e \u003c/p\u003e \u003cp\u003e \u003cstrong\u003eEthical approval:\u003c/strong\u003e \u003cp\u003eNot required.\u003c/p\u003e \u003c/p\u003e\u003cp\u003e \u003ch2\u003eUse of AI tools\u003c/h2\u003e \u003cp\u003eNo generative AI tools were used in the writing or data analysis of this manuscript.\u003c/p\u003e \u003c/p\u003e\u003ch2\u003eFunding:\u003c/h2\u003e \u003cp\u003eThis work was supported by the Polish National Science Center (Grant No. 2018/31/B/NZ7/02122).\u003c/p\u003e\u003ch2\u003eAuthor Contribution\u003c/h2\u003e\u003cp\u003eConceptualization WC, JJ and RM; methodology WC, AMW, AC and JJ; investigation WC, AMW, AC and JJ; original draft preparation WC and JJ; review and editing WC, JJ and RM; project administration and funding acquisition RM.\u003c/p\u003e\u003ch2\u003eAcknowledgement\u003c/h2\u003e\u003cp\u003eThe authors wish to thank Mrs. Ewelina Spaczyńska for her assistance with the syntheses.\u003c/p\u003e\u003ch2\u003eData Availability\u003c/h2\u003e\u003cp\u003eData are available from the corresponding author upon reasonable request.\u003c/p\u003e"},{"header":"References","content":"\u003col\u003e\n\u003cli\u003eHansson, K. \u0026amp; Brenthel, A. Imagining a post-antibiotic era: a cultural analysis of crisis and antibiotic resistance. \u003cem\u003eMed Humanit\u003c/em\u003e \u003cstrong\u003e48\u003c/strong\u003e, 381-388, doi:10.1136/medhum-2022-012409 (2022).\u003c/li\u003e\n\u003cli\u003eAbdallah, E. M., Alhatlani, B. Y., de Paula Menezes, R. \u0026amp; Martins, C. H. G. Back to Nature: Medicinal Plants as Promising Sources for Antibacterial Drugs in the Post-Antibiotic Era. \u003cem\u003ePlants (Basel)\u003c/em\u003e \u003cstrong\u003e12\u003c/strong\u003e, doi:10.3390/plants12173077 (2023).\u003c/li\u003e\n\u003cli\u003eRabi, M. The global (health) governance of antimicrobial resistance. \u003cem\u003eGlobalizations\u003c/em\u003e \u003cstrong\u003e21\u003c/strong\u003e, 1518-1538, doi:10.1080/14747731.2024.2375455 (2024).\u003c/li\u003e\n\u003cli\u003e\u003cem\u003eAntimicrobial resistance\u003c/em\u003e, \u0026lt;https://www.who.int/news-room/fact-sheets/detail/antimicrobial-resistance\u0026gt; (2024).\u003c/li\u003e\n\u003cli\u003eAntimicrobial Resistance, C. Global burden of bacterial antimicrobial resistance in 2019: a systematic analysis. \u003cem\u003eLancet\u003c/em\u003e \u003cstrong\u003e399\u003c/strong\u003e, 629-655, doi:10.1016/S0140-6736(21)02724-0 (2022).\u003c/li\u003e\n\u003cli\u003e(WHO, Geneva, Switzerland, 2023).\u003c/li\u003e\n\u003cli\u003eMirabal;, A. B., Nguyen;, A. \u0026amp; Ferrer, G. \u003cem\u003eLung Nontuberculous Mycobacterial Infections.\u003c/em\u003e, (StatPearls, 2024).\u003c/li\u003e\n\u003cli\u003eDadgostar, P. Antimicrobial Resistance: Implications and Costs. \u003cem\u003eInfect Drug Resist\u003c/em\u003e \u003cstrong\u003e12\u003c/strong\u003e, 3903-3910, doi:10.2147/IDR.S234610 (2019).\u003c/li\u003e\n\u003cli\u003ePoudel, A. N.\u003cem\u003e et al.\u003c/em\u003e The economic burden of antibiotic resistance: A systematic review and meta-analysis. \u003cem\u003ePLoS One\u003c/em\u003e \u003cstrong\u003e18\u003c/strong\u003e, e0285170, doi:10.1371/journal.pone.0285170 (2023).\u003c/li\u003e\n\u003cli\u003eJampilek, J. Design and Discovery of New Antibacterial Agents: Advances, Perspectives, Challenges. \u003cem\u003eCurr Med Chem\u003c/em\u003e \u003cstrong\u003e25\u003c/strong\u003e, 4972-5006, doi:10.2174/0929867324666170918122633 (2018).\u003c/li\u003e\n\u003cli\u003eJampilek, J. Drug repurposing to overcome microbial resistance. \u003cem\u003eDrug Discov Today\u003c/em\u003e \u003cstrong\u003e27\u003c/strong\u003e, 2028-2041, doi:10.1016/j.drudis.2022.05.006 (2022).\u003c/li\u003e\n\u003cli\u003ePaul, D.\u003cem\u003e et al.\u003c/em\u003e Artificial intelligence in drug discovery and development. \u003cem\u003eDrug Discov Today\u003c/em\u003e \u003cstrong\u003e26\u003c/strong\u003e, 80-93, doi:10.1016/j.drudis.2020.10.010 (2021).\u003c/li\u003e\n\u003cli\u003eVisan, A. I. \u0026amp; Negut, I. Integrating Artificial Intelligence for Drug Discovery in the Context of Revolutionizing Drug Delivery. \u003cem\u003eLife (Basel)\u003c/em\u003e \u003cstrong\u003e14\u003c/strong\u003e, doi:10.3390/life14020233 (2024).\u003c/li\u003e\n\u003cli\u003eRudrapal, M., Paudel, K. R. \u0026amp; Pangeni, R. Editorial: Drug repurposing and polypharmacology: A synergistic approach in multi-target based drug discovery. \u003cem\u003eFront Pharmacol\u003c/em\u003e \u003cstrong\u003e13\u003c/strong\u003e, 1101007, doi:10.3389/fphar.2022.1101007 (2022).\u003c/li\u003e\n\u003cli\u003eWeth, F. R.\u003cem\u003e et al.\u003c/em\u003e Unlocking hidden potential: advancements, approaches, and obstacles in repurposing drugs for cancer therapy. \u003cem\u003eBr J Cancer\u003c/em\u003e \u003cstrong\u003e130\u003c/strong\u003e, 703-715, doi:10.1038/s41416-023-02502-9 (2024).\u003c/li\u003e\n\u003cli\u003eMamun, M. M., Sorinolu, A. J., Munir, M. \u0026amp; Vejerano, E. P. Nanoantibiotics: Functions and Properties at the Nanoscale to Combat Antibiotic Resistance. \u003cem\u003eFront Chem\u003c/em\u003e \u003cstrong\u003e9\u003c/strong\u003e, 687660, doi:10.3389/fchem.2021.687660 (2021).\u003c/li\u003e\n\u003cli\u003eModi, S.\u003cem\u003e et al.\u003c/em\u003e Nanostructured Antibiotics and Their Emerging Medicinal Applications: An Overview of Nanoantibiotics. \u003cem\u003eAntibiotics\u003c/em\u003e \u003cstrong\u003e11\u003c/strong\u003e, 708 (2022).\u003c/li\u003e\n\u003cli\u003eYetisgin, A. A., Cetinel, S., Zuvin, M., Kosar, A. \u0026amp; Kutlu, O. Therapeutic Nanoparticles and Their Targeted Delivery Applications. \u003cem\u003eMolecules\u003c/em\u003e \u003cstrong\u003e25\u003c/strong\u003e, doi:10.3390/molecules25092193 (2020).\u003c/li\u003e\n\u003cli\u003eLi, M.\u003cem\u003e et al.\u003c/em\u003e Recent advances in nanoantibiotics against multidrug-resistant bacteria. \u003cem\u003eNanoscale Adv\u003c/em\u003e \u003cstrong\u003e5\u003c/strong\u003e, 6278-6317, doi:10.1039/d3na00530e (2023).\u003c/li\u003e\n\u003cli\u003eChifiriuc, M. C.\u003cem\u003e et al.\u003c/em\u003e Common themes in antimicrobial and anticancer drug resistance. \u003cem\u003eFront Microbiol\u003c/em\u003e \u003cstrong\u003e13\u003c/strong\u003e, 960693, doi:10.3389/fmicb.2022.960693 (2022).\u003c/li\u003e\n\u003cli\u003eTalevi, A. Multi-target pharmacology: possibilities and limitations of the \u0026quot;skeleton key approach\u0026quot; from a medicinal chemist perspective. \u003cem\u003eFront Pharmacol\u003c/em\u003e \u003cstrong\u003e6\u003c/strong\u003e, 205, doi:10.3389/fphar.2015.00205 (2015).\u003c/li\u003e\n\u003cli\u003eKabir, A. \u0026amp; Muth, A. Polypharmacology: The science of multi-targeting molecules. \u003cem\u003ePharmacol Res\u003c/em\u003e \u003cstrong\u003e176\u003c/strong\u003e, 106055, doi:10.1016/j.phrs.2021.106055 (2022).\u003c/li\u003e\n\u003cli\u003eLoscher, W. Single-Target Versus Multi-Target Drugs Versus Combinations of Drugs With Multiple Targets: Preclinical and Clinical Evidence for the Treatment or Prevention of Epilepsy. \u003cem\u003eFront Pharmacol\u003c/em\u003e \u003cstrong\u003e12\u003c/strong\u003e, 730257, doi:10.3389/fphar.2021.730257 (2021).\u003c/li\u003e\n\u003cli\u003eMakhoba, X. H., Viegas, C., Jr., Mosa, R. A., Viegas, F. P. D. \u0026amp; Pooe, O. J. Potential Impact of the Multi-Target Drug Approach in the Treatment of Some Complex Diseases. \u003cem\u003eDrug Des Devel Ther\u003c/em\u003e \u003cstrong\u003e14\u003c/strong\u003e, 3235-3249, doi:10.2147/DDDT.S257494 (2020).\u003c/li\u003e\n\u003cli\u003eOselusi, S. O., Fadaka, A. O., Wyckoff, G. J. \u0026amp; Egieyeh, S. A. Computational Target-Based Screening of Anti-MRSA Natural Products Reveals Potential Multitarget Mechanisms of Action through Peptidoglycan Synthesis Proteins. \u003cem\u003eACS Omega\u003c/em\u003e \u003cstrong\u003e7\u003c/strong\u003e, 37896-37906, doi:10.1021/acsomega.2c05061 (2022).\u003c/li\u003e\n\u003cli\u003eDoostmohammadi, A., Jooya, H., Ghorbanian, K., Gohari, S. \u0026amp; Dadashpour, M. Potentials and future perspectives of multi-target drugs in cancer treatment: the next generation anti-cancer agents. \u003cem\u003eCell Commun Signal\u003c/em\u003e \u003cstrong\u003e22\u003c/strong\u003e, 228, doi:10.1186/s12964-024-01607-9 (2024).\u003c/li\u003e\n\u003cli\u003eTran, D. N.\u003cem\u003e et al.\u003c/em\u003e Dual anticancer and antibacterial activity of fluorescent naphthoimidazolium salts. \u003cem\u003eRSC Adv\u003c/em\u003e \u003cstrong\u003e13\u003c/strong\u003e, 36430-36438, doi:10.1039/d3ra06555c (2023).\u003c/li\u003e\n\u003cli\u003eParchebafi, A.\u003cem\u003e et al.\u003c/em\u003e The dual interaction of antimicrobial peptides on bacteria and cancer cells; mechanism of action and therapeutic strategies of nanostructures. \u003cem\u003eMicrob Cell Fact\u003c/em\u003e \u003cstrong\u003e21\u003c/strong\u003e, 118, doi:10.1186/s12934-022-01848-8 (2022).\u003c/li\u003e\n\u003cli\u003eDong, Z.\u003cem\u003e et al.\u003c/em\u003e Anticancer Mechanisms and Potential Anticancer Applications of Antimicrobial Peptides and Their Nano Agents. \u003cem\u003eInt J Nanomedicine\u003c/em\u003e \u003cstrong\u003e19\u003c/strong\u003e, 1017-1039, doi:10.2147/IJN.S445333 (2024).\u003c/li\u003e\n\u003cli\u003eTolos , A. M.\u003cem\u003e et al.\u003c/em\u003e Anticancer Potential of Antimicrobial Peptides: Focus on Buforins. \u003cem\u003ePolymers\u003c/em\u003e \u003cstrong\u003e16\u003c/strong\u003e, 728 (2024).\u003c/li\u003e\n\u003cli\u003ePolanski, J., Kurczyk, A., Bak, A. \u0026amp; Musiol, R. Privileged structures - dream or reality: preferential organization of azanaphthalene scaffold. \u003cem\u003eCurr Med Chem\u003c/em\u003e \u003cstrong\u003e19\u003c/strong\u003e, 1921-1945, doi:10.2174/092986712800167356 (2012).\u003c/li\u003e\n\u003cli\u003eSolomon, V. R. \u0026amp; Lee, H. Quinoline as a privileged scaffold in cancer drug discovery. \u003cem\u003eCurrent medicinal chemistry\u003c/em\u003e \u003cstrong\u003e18\u003c/strong\u003e, 1488-1508, doi:10.2174/092986711795328382 (2011).\u003c/li\u003e\n\u003cli\u003eSong, Y. n., Xu, H., Chen, W., Zhan, P. \u0026amp; Liu, X. 8-Hydroxyquinoline: a privileged structure with a broad-ranging pharmacological potential. \u003cem\u003eMedChemComm\u003c/em\u003e \u003cstrong\u003e6\u003c/strong\u003e, 61-74, doi:10.1039/C4MD00284A (2015).\u003c/li\u003e\n\u003cli\u003eGupta, R., Luxami, V. \u0026amp; Paul, K. Insights of 8-hydroxyquinolines: A novel target in medicinal chemistry. \u003cem\u003eBioorg Chem\u003c/em\u003e \u003cstrong\u003e108\u003c/strong\u003e, 104633, doi:10.1016/j.bioorg.2021.104633 (2021).\u003c/li\u003e\n\u003cli\u003eMusiol, R., Mrozek-Wilczkiewicz, A. \u0026amp; Polanski, J. Synergy against fungal pathogens: working together is better than working alone. \u003cem\u003eCurr Med Chem\u003c/em\u003e \u003cstrong\u003e21\u003c/strong\u003e, 870-893, doi:10.2174/0929867321666131218094848 (2014).\u003c/li\u003e\n\u003cli\u003eMusiol, R., Serda, M., Hensel-Bielowka, S. \u0026amp; Polanski, J. Quinoline-based antifungals. \u003cem\u003eCurr Med Chem\u003c/em\u003e \u003cstrong\u003e17\u003c/strong\u003e, 1960-1973, doi:10.2174/092986710791163966 (2010).\u003c/li\u003e\n\u003cli\u003eSaadeh, H. A., Sweidan, K. A. \u0026amp; Mubarak, M. S. Recent Advances in the Synthesis and Biological Activity of 8-Hydroxyquinolines. \u003cem\u003eMolecules\u003c/em\u003e \u003cstrong\u003e25\u003c/strong\u003e, 4321 (2020).\u003c/li\u003e\n\u003cli\u003eMatada, B. S., Pattanashettar, R. \u0026amp; Yernale, N. G. A comprehensive review on the biological interest of quinoline and its derivatives. \u003cem\u003eBioorganic \u0026amp; Medicinal Chemistry\u003c/em\u003e \u003cstrong\u003e32\u003c/strong\u003e, 115973, doi:https://doi.org/10.1016/j.bmc.2020.115973 (2021).\u003c/li\u003e\n\u003cli\u003eDorababu, A. Recent update on antibacterial and antifungal activity of quinoline scaffolds. \u003cem\u003eArchiv der Pharmazie\u003c/em\u003e \u003cstrong\u003e354\u003c/strong\u003e, 2000232 (2021).\u003c/li\u003e\n\u003cli\u003ePrachayasittikul, V., Prachayasittikul, S., Ruchirawat, S. \u0026amp; Prachayasittikul, V. 8-Hydroxyquinolines: a review of their metal chelating properties and medicinal applications. \u003cem\u003eDrug Des Devel Ther\u003c/em\u003e \u003cstrong\u003e7\u003c/strong\u003e, 1157-1178, doi:10.2147/dddt.S49763 (2013).\u003c/li\u003e\n\u003cli\u003eMrozek-Wilczkiewicz, A.\u003cem\u003e et al.\u003c/em\u003e Investigating the anti-proliferative activity of styrylazanaphthalenes and azanaphthalenediones. \u003cem\u003eBioorg Med Chem\u003c/em\u003e \u003cstrong\u003e18\u003c/strong\u003e, 2664-2671, doi:10.1016/j.bmc.2010.02.025 (2010).\u003c/li\u003e\n\u003cli\u003eAbeydeera, N.\u003cem\u003e et al.\u003c/em\u003e Harnessing the Dual Antimicrobial Mechanism of Action with Fe(8-Hydroxyquinoline)(3) to Develop a Topical Ointment for Mupirocin-Resistant MRSA Infections. \u003cem\u003eAntibiotics (Basel)\u003c/em\u003e \u003cstrong\u003e12\u003c/strong\u003e, doi:10.3390/antibiotics12050886 (2023).\u003c/li\u003e\n\u003cli\u003eYin, X.-D.\u003cem\u003e et al.\u003c/em\u003e Design, Synthesis, and Antifungal Evaluation of 8-Hydroxyquinoline Metal Complexes against Phytopathogenic Fungi. \u003cem\u003eJournal of Agricultural and Food Chemistry\u003c/em\u003e \u003cstrong\u003e68\u003c/strong\u003e, 11096-11104, doi:10.1021/acs.jafc.0c01322 (2020).\u003c/li\u003e\n\u003cli\u003ePivarcsik, T.\u003cem\u003e et al.\u003c/em\u003e Metal Complexes of a 5-Nitro-8-Hydroxyquinoline-Proline Hybrid with Enhanced Water Solubility Targeting Multidrug Resistant Cancer Cells. \u003cem\u003eInt J Mol Sci\u003c/em\u003e \u003cstrong\u003e24\u003c/strong\u003e, doi:10.3390/ijms24010593 (2022).\u003c/li\u003e\n\u003cli\u003ePape, V. F. S.\u003cem\u003e et al.\u003c/em\u003e Structure-Activity Relationships of 8-Hydroxyquinoline-Derived Mannich Bases with Tertiary Amines Targeting Multidrug-Resistant Cancer. \u003cem\u003eJ Med Chem\u003c/em\u003e \u003cstrong\u003e65\u003c/strong\u003e, 7729-7745, doi:10.1021/acs.jmedchem.2c00076 (2022).\u003c/li\u003e\n\u003cli\u003eConan, P.\u003cem\u003e et al.\u003c/em\u003e Identification of 8-Hydroxyquinoline Derivatives That Decrease Cystathionine Beta Synthase (CBS) Activity. \u003cem\u003eInt J Mol Sci\u003c/em\u003e \u003cstrong\u003e23\u003c/strong\u003e, doi:10.3390/ijms23126769 (2022).\u003c/li\u003e\n\u003cli\u003eSzczepaniak, J., Cieslik, W., Romanowicz, A., Musiol, R. \u0026amp; Krasowska, A. Blocking and dislocation of Candida albicans Cdr1p transporter by styrylquinolines. \u003cem\u003eInt J Antimicrob Agents\u003c/em\u003e \u003cstrong\u003e50\u003c/strong\u003e, 171-176, doi:10.1016/j.ijantimicag.2017.01.044 (2017).\u003c/li\u003e\n\u003cli\u003eKos, J.\u003cem\u003e et al.\u003c/em\u003e Ring-substituted 8-hydroxyquinoline-2-carboxanilides as potential antimycobacterial agents. \u003cem\u003eBioorg Med Chem\u003c/em\u003e \u003cstrong\u003e23\u003c/strong\u003e, 4188-4196, doi:10.1016/j.bmc.2015.06.047 (2015).\u003c/li\u003e\n\u003cli\u003eKushkevych, I., V\u0026iacute;tězov\u0026aacute;, M., Kos, J., Koll\u0026aacute;r, P. \u0026amp; Jamp\u0026iacute;lek, J. Effect of selected 8-hydroxyquinoline-2-carboxanilides on viability and sulfate metabolism of Desulfovibrio piger. \u003cem\u003eJournal of Applied Biomedicine\u003c/em\u003e \u003cstrong\u003e16\u003c/strong\u003e, 241-246, doi:https://doi.org/10.1016/j.jab.2018.01.004 (2018).\u003c/li\u003e\n\u003cli\u003eJoaquim, A. R.\u003cem\u003e et al.\u003c/em\u003e Novel Antimicrobial 8-Hydroxyquinoline-Based Agents: Current Development, Structure-Activity Relationships, and Perspectives. \u003cem\u003eJ Med Chem\u003c/em\u003e \u003cstrong\u003e64\u003c/strong\u003e, 16349-16379, doi:10.1021/acs.jmedchem.1c01318 (2021).\u003c/li\u003e\n\u003cli\u003eKos, J.\u003cem\u003e et al.\u003c/em\u003e 8-Hydroxyquinoline-2-carboxanilides as antiviral agents against avian influenza virus. \u003cem\u003eChemistrySelect\u003c/em\u003e \u003cstrong\u003e4\u003c/strong\u003e, 4582\u0026ndash;4587, doi:10.1002/slct.201900873 (2019).\u003c/li\u003e\n\u003cli\u003eKumar, N.\u003cem\u003e et al.\u003c/em\u003e Quinoline derivatives volunteering against antimicrobial resistance: rational approaches, design strategies, structure activity relationship and mechanistic insights. \u003cem\u003eMol Divers\u003c/em\u003e \u003cstrong\u003e27\u003c/strong\u003e, 1905-1934, doi:10.1007/s11030-022-10537-y (2023).\u003c/li\u003e\n\u003cli\u003eMrozek-Wilczkiewicz, A.\u003cem\u003e et al.\u003c/em\u003e The synthesis and anticancer activity of 2-styrylquinoline derivatives. A p53 independent mechanism of action. \u003cem\u003eEur J Med Chem\u003c/em\u003e \u003cstrong\u003e177\u003c/strong\u003e, 338-349, doi:10.1016/j.ejmech.2019.05.061 (2019).\u003c/li\u003e\n\u003cli\u003eMrozek-Wilczkiewicz, A.\u003cem\u003e et al.\u003c/em\u003e Design, Synthesis and In Vitro Activity of Anticancer Styrylquinolines. The p53 Independent Mechanism of Action. \u003cem\u003ePLoS One\u003c/em\u003e \u003cstrong\u003e10\u003c/strong\u003e, e0142678, doi:10.1371/journal.pone.0142678 (2015).\u003c/li\u003e\n\u003cli\u003eKuczak, M., Cieślik, W., Musioł, R. \u0026amp; Mrozek-Wilczkiewicz, A. 4-Furanylvinylquinoline derivative as a new scaffold for the design of oxidative stress initiator and glucose transporter inhibitor drugs. \u003cem\u003eScientific Reports\u003c/em\u003e \u003cstrong\u003e14\u003c/strong\u003e, 28454, doi:10.1038/s41598-024-79698-0 (2024).\u003c/li\u003e\n\u003cli\u003eBissani, C., Gasparin, D. \u0026amp; Pilger, A. 8-Hydroxyquinoline, derivatives and metal-complexes: A review of antileukemia activities. \u003cem\u003eChemistrySelect\u003c/em\u003e \u003cstrong\u003e8\u003c/strong\u003e, doi:10.1002/slct.202204219 (2023).\u003c/li\u003e\n\u003cli\u003eCzaplinska, B.\u003cem\u003e et al.\u003c/em\u003e Comprehensive exploration of the optical and biological properties of new quinoline based cellular probes. \u003cem\u003eDyes and Pigments\u003c/em\u003e \u003cstrong\u003e144\u003c/strong\u003e, 119-132, doi:https://doi.org/10.1016/j.dyepig.2017.05.029 (2017).\u003c/li\u003e\n\u003cli\u003eGao, F., Zhang, X., Wang, T. \u0026amp; Xiao, J. Quinolone hybrids and their anti-cancer activities: An overview. \u003cem\u003eEuropean Journal of Medicinal Chemistry\u003c/em\u003e \u003cstrong\u003e165\u003c/strong\u003e, 59-79, doi:https://doi.org/10.1016/j.ejmech.2019.01.017 (2019).\u003c/li\u003e\n\u003cli\u003e\u003cem\u003eCloxyguin\u003c/em\u003e, \u0026lt;https://go.drugbank.com/drugs/DB15933\u0026gt; (\u003c/li\u003e\n\u003cli\u003e\u003cem\u003eClioquinol\u003c/em\u003e, \u0026lt;https://go.drugbank.com/drugs/DB04815\u0026gt; (\u003c/li\u003e\n\u003cli\u003e\u003cem\u003eOxyquinoline\u003c/em\u003e, \u0026lt;https://go.drugbank.com/drugs/DB11145\u0026gt; (\u003c/li\u003e\n\u003cli\u003e\u003cem\u003eChlorquinaldol\u003c/em\u003e, \u0026lt;https://go.drugbank.com/drugs/DB13306\u0026gt; (\u003c/li\u003e\n\u003cli\u003e\u003cem\u003eDequalinium\u003c/em\u003e, \u0026lt;https://go.drugbank.com/drugs/DB04209\u0026gt; (\u003c/li\u003e\n\u003cli\u003eCieslik, W.\u003cem\u003e et al.\u003c/em\u003e Contribution to investigation of antimicrobial activity of styrylquinolines. \u003cem\u003eBioorg Med Chem\u003c/em\u003e \u003cstrong\u003e20\u003c/strong\u003e, 6960-6968, doi:10.1016/j.bmc.2012.10.027 (2012).\u003c/li\u003e\n\u003cli\u003eCieslik, W.\u003cem\u003e et al.\u003c/em\u003e Investigation of the antimycobacterial activity of 8-hydroxyquinolines. \u003cem\u003eMed Chem\u003c/em\u003e \u003cstrong\u003e11\u003c/strong\u003e, 771-779, doi:10.2174/1573406410666150807111703 (2015).\u003c/li\u003e\n\u003cli\u003eJampilek, J.\u003cem\u003e et al.\u003c/em\u003e Investigating biological activity spectrum for novel styrylquinazoline analogues. \u003cem\u003eMolecules\u003c/em\u003e \u003cstrong\u003e14\u003c/strong\u003e, 4246-4265, doi:10.3390/molecules14104246 (2009).\u003c/li\u003e\n\u003cli\u003eMusiol, R.\u003cem\u003e et al.\u003c/em\u003e Antifungal properties of new series of quinoline derivatives. \u003cem\u003eBioorg Med Chem\u003c/em\u003e \u003cstrong\u003e14\u003c/strong\u003e, 3592-3598, doi:10.1016/j.bmc.2006.01.016 (2006).\u003c/li\u003e\n\u003cli\u003eMusiol, R.\u003cem\u003e et al.\u003c/em\u003e Investigating the activity spectrum for ring-substituted 8-hydroxyquinolines. \u003cem\u003eMolecules\u003c/em\u003e \u003cstrong\u003e15\u003c/strong\u003e, 288-304, doi:10.3390/molecules15010288 (2010).\u003c/li\u003e\n\u003cli\u003eSerda, M.\u003cem\u003e et al.\u003c/em\u003e Investigation of the biological properties of (hetero)aromatic thiosemicarbazones. \u003cem\u003eMolecules\u003c/em\u003e \u003cstrong\u003e17\u003c/strong\u003e, 13483-13502, doi:10.3390/molecules171113483 (2012).\u003c/li\u003e\n\u003cli\u003eZadrazilova, I.\u003cem\u003e et al.\u003c/em\u003e In vitro bactericidal activity of 4- and 5-chloro-2-hydroxy-N-[1-oxo-1-(phenylamino)alkan-2-yl]benzamides against MRSA. \u003cem\u003eBiomed Res Int\u003c/em\u003e \u003cstrong\u003e2015\u003c/strong\u003e, 349534, doi:10.1155/2015/349534 (2015).\u003c/li\u003e\n\u003cli\u003eCzech Collection of Microorganisms, Brno, Czech Republic.\u003c/li\u003e\n\u003cli\u003e\u003cem\u003eNational Committee for Clinical Laboratory Standards. Methods for Dilution Antimicrobial Susceptibility Tests for Bacteria that Grow Aerobically, 11th ed.; M07\u003c/em\u003e. (NCCLS, 2018).\u003c/li\u003e\n\u003cli\u003eR. Schwalbe, L. Steele-Moore \u0026amp; Goodwin, A. C. \u003cem\u003eAntimicrobial Susceptibility Testing Protocols\u003c/em\u003e. (CRC Press, 2007).\u003c/li\u003e\n\u003cli\u003e\u003cem\u003eMeasuring Cell Viability/Cytotoxicity.\u003c/em\u003e, \u0026lt;www.dojindo.eu.com/Protocol/Dojindo-Cell-Proliferation-Protocol.pdf\u0026gt; (\u003c/li\u003e\n\u003cli\u003eAbate, G., Mshana, R. N. \u0026amp; Miorner, H. Evaluation of a colorimetric assay based on 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide (MTT) for rapid detection of rifampicin resistance in Mycobacterium tuberculosis. \u003cem\u003eInt J Tuberc Lung Dis\u003c/em\u003e \u003cstrong\u003e2\u003c/strong\u003e, 1011-1016 (1998).\u003c/li\u003e\n\u003cli\u003eBueno, J. \u003cem\u003eAntitubercular In Vitro Drug Discovery: Tools for Begin the Search, Understanding Tuberculosis - New Approaches to Fighting Against Drug Resistance\u003c/em\u003e. (InTech, 2011).\u003c/li\u003e\n\u003cli\u003eGrela, E., Kozlowska, J. \u0026amp; Grabowiecka, A. Current methodology of MTT assay in bacteria - A review. \u003cem\u003eActa Histochem\u003c/em\u003e \u003cstrong\u003e120\u003c/strong\u003e, 303-311, doi:10.1016/j.acthis.2018.03.007 (2018).\u003c/li\u003e\n\u003cli\u003eAlexander, B. D.\u003cem\u003e et al.\u003c/em\u003e Reference Method for Broth Dilution Antifungal Susceptibility Testing of Yeasts: M27-A2. (Committee for Clinical Laboratory Standards, Wayne, PA, USA, 2017).\u003c/li\u003e\n\u003cli\u003ePliska, V., Testa, B. \u0026amp; van der Waterbeemd, H. \u003cem\u003eLipophilicity in Drug Action and Toxicology.\u003c/em\u003e, (Wiley-VCH: Weinheim, Germany, 1996).\u003c/li\u003e\n\u003cli\u003eCulen, M., Rezacova, A., Jampilek, J. \u0026amp; Dohnal, J. Designing a dynamic dissolution method: a review of instrumental options and corresponding physiology of stomach and small intestine. \u003cem\u003eJ Pharm Sci\u003c/em\u003e \u003cstrong\u003e102\u003c/strong\u003e, 2995-3017, doi:10.1002/jps.23494 (2013).\u003c/li\u003e\n\u003cli\u003eKerns, E. H. \u0026amp; Di, L. \u003cem\u003eDrug-Like Properties: Concepts. Structure Design and Methods: From ADME to Toxicity Optimization.\u003c/em\u003e, (Academic Press: San Diego, CA, USA, 2008).\u003c/li\u003e\n\u003cli\u003eCieslik, W., Szczepaniak, J., Krasowska, A. \u0026amp; Musiol, R. Antifungal Styryloquinolines as Candida albicans Efflux Pump Inhibitors: Styryloquinolines are ABC Transporter Inhibitors. \u003cem\u003eMolecules\u003c/em\u003e \u003cstrong\u003e25\u003c/strong\u003e, doi:10.3390/molecules25020345 (2020).\u003c/li\u003e\n\u003cli\u003eZieba, A.\u003cem\u003e et al.\u003c/em\u003e Design, Synthesis, and Anticancer and Antibacterial Activities of Quinoline-5-Sulfonamides. \u003cem\u003eMolecules\u003c/em\u003e \u003cstrong\u003e29\u003c/strong\u003e, 4044 (2024).\u003c/li\u003e\n\u003cli\u003eDolezal, M.\u003cem\u003e et al.\u003c/em\u003e Synthesis, antimycobacterial, antifungal and photosynthesis-inhibiting activity of chlorinated N-phenylpyrazine-2-carboxamides. \u003cem\u003eMolecules\u003c/em\u003e \u003cstrong\u003e15\u003c/strong\u003e, 8567-8581, doi:10.3390/molecules15128567 (2010).\u003c/li\u003e\n\u003cli\u003eStrharsky, T.\u003cem\u003e et al.\u003c/em\u003e Study of Biological Activities and ADMET-Related Properties of Novel Chlorinated N-arylcinnamamides. \u003cem\u003eInt J Mol Sci\u003c/em\u003e \u003cstrong\u003e23\u003c/strong\u003e, doi:10.3390/ijms23063159 (2022).\u003c/li\u003e\n\u003cli\u003ePortela, C. A., Smart, K. F., Tumanov, S., Cook, G. M. \u0026amp; Villas-B\u0026ocirc;as, S. G. Global metabolic response of Enterococcus faecalis to oxygen. \u003cem\u003eJ Bacteriol\u003c/em\u003e \u003cstrong\u003e196\u003c/strong\u003e, 2012-2022, doi:10.1128/jb.01354-13 (2014).\u003c/li\u003e\n\u003cli\u003eGilmore, M. S., Clewell, D. B., Ike, Y. \u0026amp; Shankar, N. \u003cem\u003eEnterococci: From Commensals to Leading Causes of Drug Resistant Infection.\u003c/em\u003e, (Massachusetts Eye and Ear Infirmary, 2014).\u003c/li\u003e\n\u003cli\u003eRamos, S., Silva, V., Dapkevicius, M. L. E., Igrejas, G. \u0026amp; Poeta, P. Enterococci, from Harmless Bacteria to a Pathogen. \u003cem\u003eMicroorganisms\u003c/em\u003e \u003cstrong\u003e8\u003c/strong\u003e, doi:10.3390/microorganisms8081118 (2020).\u003c/li\u003e\n\u003cli\u003eGilmore, M. S.\u003cem\u003e et al.\u003c/em\u003e Genes Contributing to the Unique Biology and Intrinsic Antibiotic Resistance of Enterococcus faecalis. \u003cem\u003emBio\u003c/em\u003e \u003cstrong\u003e11\u003c/strong\u003e, doi:10.1128/mBio.02962-20 (2020).\u003c/li\u003e\n\u003cli\u003eFraunfelter, V. M.\u003cem\u003e et al.\u003c/em\u003e Quinoline Compounds Targeting the c-Ring of ATP Synthase Inhibit Drug-Resistant Pseudomonas aeruginosa. \u003cem\u003eACS Infect Dis\u003c/em\u003e \u003cstrong\u003e9\u003c/strong\u003e, 2448-2456, doi:10.1021/acsinfecdis.3c00317 (2023).\u003c/li\u003e\n\u003cli\u003eNubel, U.\u003cem\u003e et al.\u003c/em\u003e A timescale for evolution, population expansion, and spatial spread of an emerging clone of methicillin-resistant Staphylococcus aureus. \u003cem\u003ePLoS Pathog\u003c/em\u003e \u003cstrong\u003e6\u003c/strong\u003e, e1000855, doi:10.1371/journal.ppat.1000855 (2010).\u003c/li\u003e\n\u003cli\u003e\u003cem\u003eBedaquiline\u003c/em\u003e, \u0026lt;go.drugbank.com/drugs/DB08903\u0026gt; (\u003c/li\u003e\n\u003cli\u003eMapari, M., Bhole, R. P., Khedekar, P. B. \u0026amp; Chikhale, R. V. Challenges in targeting mycobacterial ATP synthase: The known and beyond. \u003cem\u003eJournal of Molecular Structure\u003c/em\u003e \u003cstrong\u003e1247\u003c/strong\u003e, 131331, doi:https://doi.org/10.1016/j.molstruc.2021.131331 (2022).\u003c/li\u003e\n\u003c/ol\u003e"},{"header":"Schemes","content":"\u003cp\u003eSchemes 1 and 2 are available in the Supplementary Files section.\u003c/p\u003e"},{"header":"Table 1","content":"\u003cp\u003eTable 1 is available in the Supplementary Files section.\u003c/p\u003e"}],"fulltextSource":"","fullText":"","funders":[],"hasAdminPriorityOnWorkflow":false,"hasManuscriptDocX":true,"hasOptedInToPreprint":true,"hasPassedJournalQc":"","hasAnyPriority":false,"hideJournal":false,"highlight":"","institution":"","isAcceptedByJournal":false,"isAuthorSuppliedPdf":false,"isDeskRejected":"","isHiddenFromSearch":false,"isInQc":false,"isInWorkflow":false,"isPdf":false,"isPdfUpToDate":true,"isWithdrawnOrRetracted":false,"journal":{"display":true,"email":"[email protected]","identity":"scientific-reports","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":false,"externalIdentity":"scirep","sideBox":"Learn more about [Scientific Reports](http://www.nature.com/srep/)","snPcode":"","submissionUrl":"","title":"Scientific Reports","twitterHandle":"","acdcEnabled":true,"dfaEnabled":true,"editorialSystem":"stoa","reportingPortfolio":"Scientific Reports","inReviewEnabled":true,"inReviewRevisionsEnabled":true},"keywords":"Styrylquinolines, synthesis, antibacterial activity, antimycobacterial activity, antifungal activity, antiproliferative effect","lastPublishedDoi":"10.21203/rs.3.rs-9163171/v1","lastPublishedDoiUrl":"https://doi.org/10.21203/rs.3.rs-9163171/v1","license":{"name":"CC BY 4.0","url":"https://creativecommons.org/licenses/by/4.0/"},"manuscriptAbstract":"\u003cp\u003eA total of 64 ring-substituted 2-styrylquinolines were designed and tested against a battery of microbial pathogens: \u003cem\u003eStaphylococcus aureus\u003c/em\u003e ATCC 29213, \u003cem\u003eEnterococcus faecalis\u003c/em\u003e ATCC 29212, clinical isolates of methicillin-resistant \u003cem\u003eS. aureus\u003c/em\u003e (MRSA), \u003cem\u003eMycobacteium tuberculosis\u003c/em\u003e H37Ra/ATCC 25177, \u003cem\u003eMycobacterium smegmatis\u003c/em\u003e ATCC 700084, \u003cem\u003eMycobacterium kansasii\u003c/em\u003e DSM 44162, \u003cem\u003eCandida albicans\u003c/em\u003e CCM 8361, \u003cem\u003eCandida krusei\u003c/em\u003e CCM 8271 and \u003cem\u003eCandida parapsilosis\u003c/em\u003e CCM 8260. In addition, all compounds were investigated for their anticancer potential on colon cancer cell lines HCT 116 p53+/+ and HCT 116 p53-/- as well as the effect against normal human dermal fibroblasts (NHDF). Twenty derivatives showed remarkable antimicrobial activity comparable to or better than clinically used drugs (ampicillin, ciprofloxacin, rifampicin, amphotericin B). The most effective compounds were substituted on styryl with 2,6-Cl, 2-NO\u003csub\u003e2\u003c/sub\u003e, 2,4-NO\u003csub\u003e2\u003c/sub\u003e, 4-CN, 2-OAc-5-Cl and 2-OH-5-NO\u003csub\u003e2\u003c/sub\u003e. Chlorination of the quinoline at the 5- and 7-position and the free hydroxylic group at the 8-position of the quinoline resulted in increased and broadened efficacy. All the antimicrobial active derivatives did not show significant effect on normal human dermal fibroblasts, except for 2,6-Cl-styryl derivatives. The antimycobacterial active compounds were able to inhibit cellular respiration in all tested mycobacterial species. (\u003cem\u003eE\u003c/em\u003e)-5,7-dichloro-2-[2-(2-nitrophenyl)vinyl]-quinolin-8-ol (\u003cb\u003eD4\u003c/b\u003e) and (\u003cem\u003eE\u003c/em\u003e)-5,7-dichloro-2-[2-(2,4-dinitrophenyl)vinyl]-quinolin-8-ol (\u003cb\u003eD10\u003c/b\u003e) were the most antimicrobial effective agents simultaneously with high anticancer activity and negligible cytotoxicity against normal human cells. Thus, promising active agents with dual, anti-infectious, and anticancer effects, were identified.\u003c/p\u003e","manuscriptTitle":"Insights into Antimicrobial Potential of Styrylquinoline Derivatives","msid":"","msnumber":"","nonDraftVersions":[{"code":1,"date":"2026-04-30 11:56:23","doi":"10.21203/rs.3.rs-9163171/v1","editorialEvents":[{"type":"communityComments","content":0},{"type":"reviewerAgreed","content":"286088259984215383238396078964269697084","date":"2026-05-18T05:07:40+00:00","index":"hide","fulltext":""},{"type":"reviewersInvited","content":"","date":"2026-04-22T08:45:06+00:00","index":"","fulltext":""},{"type":"editorInvited","content":"","date":"2026-04-22T07:44:44+00:00","index":"","fulltext":""},{"type":"editorAssigned","content":"","date":"2026-04-20T08:53:21+00:00","index":"","fulltext":""},{"type":"checksComplete","content":"","date":"2026-04-13T07:17:13+00:00","index":"","fulltext":""},{"type":"submitted","content":"Scientific Reports","date":"2026-04-12T21:24:40+00:00","index":"","fulltext":""}],"status":"published","journal":{"display":true,"email":"[email protected]","identity":"scientific-reports","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":false,"externalIdentity":"scirep","sideBox":"Learn more about [Scientific Reports](http://www.nature.com/srep/)","snPcode":"","submissionUrl":"","title":"Scientific Reports","twitterHandle":"","acdcEnabled":true,"dfaEnabled":true,"editorialSystem":"stoa","reportingPortfolio":"Scientific Reports","inReviewEnabled":true,"inReviewRevisionsEnabled":true}}],"origin":"","ownerIdentity":"f6cb72a5-14ed-44e3-b017-e5d3edc6c72e","owner":[],"postedDate":"April 30th, 2026","published":true,"recentEditorialEvents":[{"type":"reviewerAgreed","content":"286088259984215383238396078964269697084","date":"2026-05-18T05:07:40+00:00","index":34,"fulltext":""}],"rejectedJournal":[],"revision":"","amendment":"","status":"under-review","subjectAreas":[{"id":66808587,"name":"Biological sciences/Cancer"},{"id":66808588,"name":"Biological sciences/Drug discovery"},{"id":66808589,"name":"Biological sciences/Microbiology"}],"tags":[],"updatedAt":"2026-04-30T11:56:23+00:00","versionOfRecord":[],"versionCreatedAt":"2026-04-30 11:56:23","video":"","vorDoi":"","vorDoiUrl":"","workflowStages":[]},"version":"v1","identity":"rs-9163171","journalConfig":"researchsquare"},"__N_SSP":true},"page":"/article/[identity]/[[...version]]","query":{"redirect":"/article/rs-9163171","identity":"rs-9163171","version":["v1"]},"buildId":"XKTyCvWXoU3ODBz1xrDgd","isFallback":false,"isExperimentalCompile":false,"dynamicIds":[84888],"gssp":true,"scriptLoader":[]}