Synthesis and cytotoxic evaluation of ester analogues of (-)-curine

Synthesis and cytotoxic evaluation of ester analogues of (-)-curine | 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 Research Article Synthesis and cytotoxic evaluation of ester analogues of (-)-curine Suwadee Chokchaisiri, Sittisak Kumjun, Chutamas Thepmalee, Thitima Rukachaisirikul This is a preprint; it has not been peer reviewed by a journal. https://doi.org/ 10.21203/rs.3.rs-4140864/v1 This work is licensed under a CC BY 4.0 License Status: Posted Version 1 posted You are reading this latest preprint version Abstract This study presents the synthesis and cytotoxic evaluation of ester analogues derived from (-)-curine, a natural compound isolated from the roots of Cissampelos pareira (Menispermaceae). The synthesis involved the preparation of mono- and di-acetylcurine, along with four other ester derivatives, through diverse chemical transformations. Structural characterization of the synthesized compounds was performed using spectroscopic techniques and high-resolution mass spectrometry. Cytotoxicity assessments were conducted across various cancer cell lines, including MCF-7, MDA-MB-231, and Huh-7, as well as non-cancerous HEK293T cells, utilizing the MTT assay. Notably, compounds 4 and 5 demonstrated significant cytotoxic activities superior to the parent compound 1 and even matched or exceeded the cytotoxic effects induced by cisplatin, a conventional chemotherapeutic agent, across all tested cancer cell lines. These findings highlight the potential of compounds 4 and 5 as promising candidates for further development as potent cytotoxic agents in cancer therapy. Synthesis Cytotoxicity Ester Analogues Cancer Therapy (-)-Curine Introduction (-)-Curine, a bisbenzylisoquinoline (BBIQ) alkaloid, is the primary compound derived from the methanol extract of Cissampelos pareira roots. This plant, known for its diverse medicinal properties, has been historically used in traditional medicine to address a spectrum of ailments, including coughs, delirium, fever, madness, epilepsy, and convulsions [ 1 ]. Its global application extends to serving as a stimulant, sedative, analgesic, febrifuge, antioxidant, tonic, and narcotic agent [ 1 ]. The pharmacological potential of curine has attracted scientific interest, with earlier investigations uncovering its vasodilator effects attributed to the inhibition of calcium influx, possibly mediated by the direct blockade of L-type Ca 2+ channels [ 2 ]. Additionally, curine has exhibited anti-inflammatory effects [ 3 ], anti-allergic properties [ 4 – 6 ] and cytotoxicity [ 7 – 8 ], suggesting its broad spectrum of biological activities. Despite its promising pharmacological profile, the chemical modification of curine has emerged as a strategy to enhance its therapeutic efficacy and selectivity. Chemical modification of natural compounds is a prevailing approach in medicinal chemistry aimed at developing more potent pharmacological agents. By employing straightforward synthetic methodologies, the production of modified curine analogs with robust bioactivity becomes feasible, thus presenting opportunities for the pharmaceutical industry. The current study focuses on the chemical modification of curine ( 1 ) to synthesize analogs (Scheme 1 – 2 ), with some exhibiting notable cytotoxic activities. This approach underscores the importance of structural manipulation in elucidating structure-activity relationships and enhancing the pharmacological properties of natural compounds like curine. Results and discussion Chemistry The chemical modifications described in this study focus on the ester analogues at the C-7 and C-12 hydroxyl groups of (-)-curine ( 1 ). The first series of ester-(-)-curine ( 1 ) analogues were prepared as shown in Scheme 1 . Acetylation of the resulting (-)-curine ( 1 ) at C-7 and C-12 in the presence of acetic anhydride at room temperature for 3 h afforded the mono- and di-acetylcurine products 7,12-Diacetoxylcurine ( 2 ) and 7-Acetoxylcurine ( 3 ). Compound 4 , 7-(1,6-dihydrocyclopenta[c]pyrazole-3-carboxyl)-curine, was synthesized by reacting compound 1 with 1,6-dihydrocyclopenta[c]pyrazole-3-carboxylic acid, N,N'-diisopropylcarbodiimide (DIC), in dichloromethane, employing 4- N , N -dimethylaminopyridine (DMAP) as a catalyst, resulting in a yield of 35.3% (Scheme 2 ). 7,12-Dithiophene-2-carbonylcurine ( 5 ) was obtained in excellent yield (94.1%) through the reaction of compound 1 with thiophene-2-carbonyl chloride, DIC, in dichloromethane, with DMAP serving as the catalyst (Scheme 2 ). The synthesis of 7-(4-Chlorocinamoyl)-curine ( 6 ) involved the reaction of compound 1 with 4-chlorocinamic acid, DIC, in dichloromethane, facilitated by DMAP, resulting in a yield of 35.2% (Scheme 2 ). 7,12-di-(3-nitrobenzoyl)-curine ( 7 ) was obtained by reacting compound 1 with 3-nitrobenzoic acid, DIC, in dichloromethane in the presence of DMAP, yielding 20.2% (Scheme 2 ). The preparation of 7,12-di-(trans-3-nitrocinamoyl)-curine ( 8 ) involved the reaction of compound 1 with trans-3-nitrocinamic acid, DIC, in dichloromethane, using DMAP as the catalyst, resulting in a yield of 47.0% (Scheme 2 ). All synthetic compounds were purified by column chromatography and characterized by spectroscopic techniques and high-resolution mass spectrometry (see Experimental). Cytotoxic evaluation of (-)-curine and its analogs against cancer cell lines The cytotoxic activities of (-)-curine (compound 1 ) and its analogs ( 2–8 ), alongside the positive control cisplatin, were evaluated against triple-negative breast cancer (MDA-MB231), hepatocellular carcinoma (Huh-7), human breast cancer (MCF-7), and non-cancerous human embryonic kidney 293T cells (HEK293T), utilizing the MTT assay, as depicted in Table 1 . Compounds 1 , 2 , 3 , 6 , 7 , and 8 demonstrated IC 50 values greater than 100 µM across all cell lines, indicating minimal cytotoxic effects within the tested concentration range. Conversely, compounds 4 and 5 exhibited varying degrees of cytotoxicity against the cell lines. Compound 4 displayed IC 50 values of 57.52 ± 1.20 µM, 37.44 ± 1.87 µM, and 45.33 ± 1.96 µM against MDA-MB-231, Huh-7, and MCF-7 cells, respectively, while showing no significant effect on HEK-293T cells (> 100 µM). Compound 5 demonstrated similar potency, with IC 50 values of 58.97 ± 3.07 µM, 33.00 ± 1.82 µM, and 23.33 ± 1.67 µM against MDA-MB-231, Huh-7, and MCF-7 cells, respectively, and 58.84 ± 3.06 µM against HEK-293T cells. Notably, compounds 4 and 5 exhibited comparable or superior cytotoxic effects against the tested cancer cell lines compared to the positive control cisplatin, indicating their potential as promising candidates for further investigation as cytotoxic agents. These findings suggest the importance of exploring structural modifications to enhance the pharmacological properties of (-)-curine and its analogs, potentially leading to the development of novel anticancer therapeutics. Table 1 Cytotoxic activities of compounds 1 − 8 Compound Cytotoxicity (IC 50 , µ M) MDA-MB-231 Huh-7 MCF-7 HEK-293T 1 > 100 > 100 > 100 > 100 2 > 100 > 100 > 100 > 100 3 > 100 > 100 > 100 > 100 4 57.52 ± 1.20 37.44 ± 1.87 45.33 ± 1.96 > 100 5 58.97 ± 3.07 33.00 ± 1.82 23.33 ± 1.67 58.84 ± 3.06 6 > 100 > 100 > 100 > 100 7 > 100 > 100 > 100 > 100 8 > 100 > 100 > 100 > 100 Cisplatin a 28.42 ± 1.73 46.54 ± 2.89 37.55 ± 1.81 60.22 ± 3.08 a Positive control Conclusion In conclusion, the study focused on the chemical modification of (-)-curine, a bisbenzylisoquinoline alkaloid derived from the roots of Cissampelos pareira , aiming to synthesize analogs with enhanced pharmacological properties, particularly cytotoxicity against various cancer cell lines. The synthesis of seven ester analogs of (-)-curine was successfully achieved through straightforward synthetic methodologies involving esterification reactions with different carboxylic acids. The compounds were purified and characterized using spectroscopic techniques and high-resolution mass spectrometry. Evaluation of cytotoxic potential across multiple cancer cell lines revealed compounds 4 and 5 to exhibit significant activity, surpassing (-)-curine and matching or exceeding cisplatin's effects. These results highlight the potential of chemical modification strategies to enhance natural compounds' pharmacological properties. Compounds 4 and 5 , particularly promising, warrant further investigation into their mechanisms of action and in vivo efficacy, suggesting potential clinical applications in cancer therapy. Future studies should delve into structure-activity relationships to optimize (-)-curine analogs' cytotoxicity and selectivity. Experimental section General experimental procedures Optical rotations were measured on a JASCO-1020 polarimeter. IR spectra were obtained using a Frontier FT-IR Perkin-Elmer spectrophotometer. 1 H and 13 C NMR spectra were recorded on a Bruker AVANCE 400 FT-NMR spectrometer, operating at 400 MHz ( 1 H) and 100 MHz ( 13 C). ESTOFMS spectra were measured with a Bruker micrOTOF-II mass spectrometer. Unless otherwise indicated, column chromatography was carried out using Merck silica gel 60 (< 0.063 mm). For TLC, Merck precoated silica gel 60 F 254 plates were used. Spots on TLC were detected under UV light and by spraying with anisaldehyde-H 2 SO 4 reagent followed by heating. Extraction and isolation of (−)-curine (−)- Curine was isolated from the roots of Cissampelos pareira (Menispermaceae). Its structure was confirmed by spectroscopic methods and comparison with the reported literature [ 1 ]. (−) -Curine (1) Pale yellow power; \({\text{[α]}}_{\text{D}}^{\text{26}}\) -167.9˚( c 0.97, CHCl 3 ); IR ν max : 3370, 2932, 2839, 2796, 1611, 1503, 1444, 1273, 1213, 1166, 1109, 1055, 907, 831, 801, 725 cm − 1 ; 1 H NMR (CDCl 3 , 400 MHz,): δ 7.08 (1H, d, J = 8.0 Hz, H-14′), 6.92 (1H, d, J = 8.0 Hz, H-14), 6.79 (1H, d, J = 8.0 Hz, H-13), 6.68 (1H, partially overlapping signal, H-13′), 6.66 (1H, s, H-5′), 6.63 (1H, d, J = 8.0 Hz, H-11′), 6.60 (1H, br s, H-10), 6.53 (1H, s, H-5), 6.44 (1H, d, J = 8.0 Hz, H-10′), 5.94 (1H, br s, H-8′), 3.88 (3H, s, 6′-OCH 3 ), 3.55 (1H, d, J = 7.6 Hz, H-1), 3.44 (1H, d, J = 9.2 Hz, H-1′), 3.31 (1H, m, H-3), 3.22 (1H, m, H-3′), 3.13, 2.53 (2H, br d, J = 11.8 Hz, H-α′), 2.97 (1H, overlapping signal, H-4), 2.92, 2.71 (2H, overlapping signal, H-4′), 2.87 (3H, s, 6-OCH 3 ), 2.85 (1H, overlapping signal, H-3), 2.81, 2.74 (2H, overlapping signal, H-α), 2.79 (1H, overlapping signal, H-3′), 2.49 (3H, s, N′-CH 3 ), 2.42 (1H, dd, J = 16.8, 3.8 Hz, H-4), 2.27 (3H, s, N-CH 3 ); 13 C NMR (CDCl 3 , 100 MHz,): δ 155.4 (C-12′), 148.6 (C-6′), 146.5 (C-6), 146.3 (C-12), 144.2 (C-11), 143.2 (C-7′), 138.5 (C-8), 137.3 (C-7), 133.7 (C-9), 132.4 (C-9′), 132.2 (C-10′), 129.6 (C-4a′), 129.5 (C-14′), 126.6 (C-14), 125.1 (C-4a), 124.5 (C-8a), 124.5 (C-8a′), 120.7 (C-10), 120.2 (C-8′), 115.5 (C-11′), 115.2 (C-13), 113.3 (C-13′), 112.3 (C-5′), 108.1 (C-5), 65.4 (C-1′), 60.4 (C-1), 56.1 (6-O C H 3 ), 56.0 (6′-O C H 3 ), 45.7 (C-3′), 43.9 (C-3), 42.2 (N′- C H 3 ), 41.7 (N- C H 3 ), 39.9 (C-α), 39.7 (C- α′), 25.3 (C-4′), 21.9 (C-4); ESI MS m/z 595.9 [M + H] + . Synthesis of (−)-curine ester analogues Preparation of Compounds 2 and 3 A mixture of compound 1 (50 mg, 0.08 mmol) was dissolved in CH 2 Cl 2 (5 ml) and acetic anhydride (0.1 ml) was added. The reaction mixture was stirred at room temperature for 3 h. The mixture was poured into water (30 ml) and the solution was extracted with CH 2 Cl 2 (100 ml). The organic phase was washed with water (3×20 ml) and dried over anhydrous Na 2 SO 4 . The solvent was removed under reduced pressure and the product was purified by column chromatography using 4% MeOH in CH 2 Cl 2 as eluent to yield compounds 2 (22.0 mg, 37.5%) and 3 (15.1 mg, 25%). 7,12-Diacetoxylcurine (2) Pale-yellow powder; \({\text{[α]}}_{\text{D}}^{\text{27}}\) -114.34 (c = 0.32, CH 2 Cl 2 ); IR ν max : 2931, 2845, 1764, 1609, 1503, 1418, 1367, 1271, 1214, 1186, 1112, 1055, 1011, 905, 834, 726 cm − 1 ; 1 H NMR (CDCl 3 , 400 MHz,): δ 7.10 (1H, d, J = 8.0 Hz, H-14), 7.09 (1H, d, J = 8.0 Hz, H-14′), 6.91 (1H, d, J = 8.0 Hz, H-13), 6.69 (1H, d, J = 8.0 Hz, H-13′), 6.63 (1H, br s, H-5′), 6.62 (1H, d, J = 8.0 Hz, H-11′), 6.58 (1H, s, H-5), 6.58 (1H, br s, H-10), 6.40 (1H, d, J = 8.0 Hz, H-10′), 5.48 (1H, s, H-8′), 3.79 (3H, s, 6-OCH 3 ), 3.78 (3H, s, 6′-OCH 3 ), 3.55 (1H, d, J = 10.8 Hz, H-1′), 3.48 (1H, d, J = 8.4 Hz, H-1), 3.30 (2H, m, H-3,3′), 3.26, (2H, br d, J = 11.6 Hz, H- α, α′), 2.98 (2H, overlapping signal, H-4, 4′), 2.87 (1H, overlapping signal, H-3), 2.82 (1H, overlapping signal, H-3′), 2.66 (2H, d, J = 14.4 Hz, H-α), 2.53 (3H, s, N′-CH 3 ), 2.45 (1H, dd, J = 18.0, 4.0 Hz, H-4), 2.24 (3H, s, N-CH 3 ), 2.06 (3H, s, H-2′′), 2.01 (3H, s, H-2′′′); 13 C NMR (CDCl 3 , 100 MHz,): δ 168.8 (C-1′′′), 168.4 (C-1′′), 155.2 (C-12′),150.8 (C-6), 148.8 (C-6′), 146.7 (C-11), 144.5 (C-8), 143.8 (C-7′), 140.6 (C-12), 140.3 (C-9), 132.9 (C-10′), 132.2 (C-7), 131.3 (C-9′), 129.8 (C-14′), 126.9 (C-4a′), 126.5 (C-8a′), 125.8 (C-14), 124.1 (C-4a, C-8a), 122.7 (C-13), 122.2 (C-10), 117.7 (C-8′), 115.2 (C-11′), 114.1 (C-13′), 112.3 (C-5′), 108.9 (C-5), 64.9 (C-1′), 60.6 (C-1), 56.0 (6-O C H 3 ), 55.9 (6′-O C H 3 ), 44.8 (C-3′), 43.3 (C-3), 41.5 (N- C H 3 ), 41.1 (N′- C H 3 ), 40.2 (C-α), 39.5 (C- α′), 24.0 (C-4′), 21.9 (C-4), 20.4 (C-2′′′), 20.1 (C-2′′); HR-TOF-MS (ESI + ): m/z 679.3029 [M + H] + (calcd. for C 40 H 43 N 2 O 8 , 679.3014). The physical and spectral data were in agreement with those reported in the literature [ 9 ]. 7-Acetoxylcurine (3) Pale-yellow powder; \({\text{[α]}}_{\text{D}}^{\text{27}}\) -132.57 (c = 0.35, CH 2 Cl 2 ); IR ν max : 3380, 2928, 2845, 1765, 1609, 1579, 1504, 1438, 1368, 1271, 1188, 1112, 1056, 1013, 902, 833, 726 cm − 1 ; 1 H NMR (CDCl 3 , 400 MHz,): δ 7.12 (1H, d, J = 7.6 Hz, H-14′), 6.91 (1H, d, J = 7.6 Hz, H-14), 6.79 (1H, d, J = 7.6 Hz, H-13), 6.68 (1H, overlapping signal, H-5′), 6.68 (1H, overlapping signal, H-13′), 6.61 (1H, s, H-5), 6.65 (1H, br s, H-10), 6.64 (1H, overlapping signal, H-11′), 6.54 (1H, d, J = 7.6 Hz, H-10′), 5.92 (1H, s, H-8′), 3.89 (3H, s, 6′-OCH 3 ), 3.83 (3H, s, 6-OCH 3 ), 3.52 (1H, d, J = 8.0 Hz, H-1), 3.48 (1H, d, J = 15.2 Hz, H-1′), 3.36 (1H, m, H-3), 3.29 (1H, m, H-3′), 3.24 (1H, overlapping signal, H-α′), 2.98 (1H, m, H-4), 2.94 (1H, m, H-4′), 2.90 (1H, overlapping signal, H-3), 2.81 (1H, overlapping signal, H-4′), 2.77 (2H, overlapping signal, H-α, α′), 2.55 (1H, overlapping signal, H-α), 2.53 (3H, s, N′-CH 3 ), 2.48 (1H, dd, J = 17.4, 4.2 Hz, H-4), 2.25 (3H, s, N-CH 3 ), 2.11 (3H, s, H-2′′); 13 C NMR (CDCl 3 , 100 MHz,): δ 168.6 (C-1′′), 155.3 (C-12′), 150.7 (C-6), 148.7 (C-6′), 146.4 (C-12), 144.6 (C-8), 144.0 (C-11), 143.4 (C-7′), 133.6 (C-9), 132.9 (C-7), 132.2 (C-10′), 131.7 (4a′, C-9′), 129.6 (C-14′), 127.1 (C-8a′), 126.8 (C-14), 124.3 (C-4a), 123.6 (C-8a), 120.9 (C-10), 119.8 (C-8′), 115.7 (C-11′), 115.3 (C-13), 113.8 (C-13′), 112.3 (C-5′), 108.9 (C-5), 65.5 (C-1′), 60.4 (C-1), 56.1 (6-O C H 3, 6′-O C H 3 ), 45.7 (C-3′), 43.6 (C-3), 42.0 (N- C H 3 ), 41.7 (N′- C H 3 ), 39.8 (C-α, α′), 25.3 (C-4′), 22.2 (C-4), 20.2 (C-2′′); HR-TOF-MS (ESI + ): m/z 637.2918 [M + H] + (calcd. for C 38 H 41 N 2 O 7 , 637.2908). Preparation of Compound 4 A mixture of compound 1 (100 mg, 0.17 mmol) was dissolved in CH 2 Cl 2 (10 ml) and N,N′-diisopropylcarbodiimide (DIC) (0.1 ml), 4-N,N′-dimethylaminopyridine (DMAP) (1 mg, 0.01 mmol) and 1,6-dihydrocyclopenta[c]pyrazole-3-carboxylic acid (10 mg, 0.07 mmol) was added. The reaction mixture was stirred at room temperature for 72 h. The mixture was poured into water (30 ml) and the solution was extracted with CH 2 Cl 2 (100 ml). The organic phase was washed with water (3×20 ml) and dried over anhydrous Na 2 SO 4 . The solvent was removed under reduced pressure and the product was purified by column chromatography using 4% MeOH in CH 2 Cl 2 to yield compound 4 (41.5 mg, 35.3%). 7-(1,6-dihydrocyclopenta[c]pyrazole-3-carboxyl)-curine (4) Pale-yellow powder; \({\text{[α]}}_{\text{D}}^{\text{27}}\) -196.10 (c = 0.30, CH 2 Cl 2 ); IR ν max : 3312, 2932, 2849, 1740, 1609, 1504, 1441, 1272, 1209, 1108, 1023, 834, 765 cm − 1 ; 1 H NMR (CDCl 3 , 400 MHz,): δ 7.07 (1H, d, J = 8.0 Hz, H-14′), 6.92 (1H, d, J = 8.0 Hz, H-14), 6.78 (1H, d, J = 8.0 Hz, H-13), 6.69 (1H, overlapping signal, H-13′), 6.65 (1H, br s, H-5′), 6.63 (1H, overlapping signal, H-5, 5′′), 6.57 (1H, d, J = 8.0 Hz, H-11′), 6.55 (2H, overlapping signal, H-10,4′′), 6.42 (1H, d, J = 7.6 Hz, H-10′), 5.91 (1H, s, H-8′), 3.86 (3H, s, 6′-OCH 3 ), 3.80 (3H, s, 6-OCH 3 ), 3.56 (1H, d, J = 7.6 Hz, H-1), 3.47 (1H, d, J = 5.6 Hz, H-1′), 3.35 (1H, m, H-3), 3.25 (1H, m, H-3′), 3.17, 2.55 (2H, br d, J = 11.6 Hz, H-α′), 3.01 (1H, m, H-4), 2.97 (1H, overlapping signal, H-4′), 2.90 (1H, overlapping signal, H-3), 2.81 (1H, overlapping signal, H-3′), 2.78 (1H, overlapping signal, H-α), 2.74 (1H, d, J = 12.4 Hz, H-α), 2.67 (1H, m, H-4′), 2.49 (1H, overlapping signal, H-4), 2.48 (3H, s, N′-CH 3 ), 2.34 (2H, m, H-6′′), 2.27 (3H, s, N-CH 3 ); 13 C NMR (CDCl 3 , 100 MHz,): δ 157.5 (C-7′′), 155.4 (C-12′), 150.8 (C-6), 148.7 (C-6′), 146.3 (C-12), 144.7 (C-8), 144.0 (C-11), 143.2 (C-7′), 133.5 (C-7), 133.3 (C-9), 132.4 (C-9′), 132.0 (C-10′), 130.9 (C-3a′′), 130.6 (C-4a′), 129.6 (C-14′), 129.3 (C-8a′), 129.1(C-6a′′), 126.5 (C-14), 124.6 (C-4a, 8a,), 120.7 (C-10), 120.0 (C-8′), 115.4 (C-11′), 115.3 (C-13, 5′′), 113.9 (C-13′), 112.3 (C-5′), 109.0 (C-5), 108.1 (C-4′′), 65.3 (C-1′), 60.3 (C-1), 56.1 (6-O C H 3 ), 55.9 (6′-O C H 3 ), 45.6 (C-3′), 43.6 (C-3), 42.0 (N- C H 3 ), 41.8 (N′- C H 3 ), 39.7 (C-α, α′), 29.9 (C-6′′), 25.1 (C-4′), 24.4 (C-4); HR-TOF-MS (ESI + ): m/z 727.3105 [M + H] + (calcd. for C 45 H 43 N 4 O 7 , 727.3126). Preparation of Compound 5 A mixture of compound 1 (100 mg, 0.17 mmol) was dissolved in CH 2 Cl 2 (10 ml). To this solution, N,N'-diisopropylcarbodiimide (DIC) (0.1 ml), 4-N,N'-dimethylaminopyridine (DMAP) (1 mg, 0.01 mmol), and thiophene-2-carbonyl chloride (10 mg, 0.08 mmol) were added and stirred at room temperature for 24 h. The mixture was poured into water (30 ml) and the solution was extracted with CH 2 Cl 2 (100 ml). The organic phase was washed with water (3×20 ml) and dried over anhydrous Na 2 SO 4 . The solvent was removed under reduced pressure and the product was purified by column chromatography using 6% MeOH in CH 2 Cl 2 to yield compound 5 (108.9 mg, 94.1%). 7,12-Dithiophene-2-carbonylcurine (5) Pale yellow powder; \({\text{[α]}}_{\text{D}}^{\text{27}}\) -211.59 (c = 0.32, CH 2 Cl 2 ); IR ν max : 3341, 2929, 2841, 1729, 1609, 1502, 1414, 1359, 1250, 1201, 1112, 1050, 1014, 834, 734 cm − 1 ; 1 H NMR (CDCl 3 , 400 MHz,): δ 7.74 (1H, br s, H-3′′′), 7.72 (1H, br s, H-3′′), 7.52 (2H, br s, H-5′′, H-5′′′), 7.19 (1H, d, J = 7.6 Hz, H-14), 7.06 (1H, d, J = 7.6 Hz, H-13), 7.05 (1H, overlapping signal, H-4′′′), 7.01 (2H, overlapping signal, H-14′,4′′), 6.74 (1H, br s, H-11′), 6.65 (2H, overlapping signal, H-13′, H-5), 6.70 (1H, br s, H-10), 6.44 (1H, br s, H-5′), 6.44 (1H, overlapping signal, H-10′), 5.49 (1H, s, H-8′), 3.82 (3H, s, 6-OCH 3 ), 3.53 (1H, d, J = 8.0 Hz, H-1), 3.42, 2.94 (2H, overlapping signal, H-3), 3.42 (3H, s, 6′-OCH 3 ), 3.36 (1H, d, J = 8.0 Hz, H-1′), 3.11 (1H, br d, J = 12.0 Hz, H-α′), 3.19 (1H, m, H-3′), 3.05, 2.49 (2H, overlapping signal, H-4), 2.91 (1H, overlapping signal, H-4′), 2.86, 2.76 (2H, overlapping signal, H-α), 2.76 (1H, overlapping signal, H-3′), 2.63 (1H, m, H-4′), 2.49 (1H, overlapping signal, H-α′), 2.49 (3H, s, N′-CH 3 ), 2.29 (3H, s, N-CH 3 ); 13 C NMR (CDCl 3 , 100 MHz,): δ 159.8 (C-6′′′), 159.5 (C-6′′), 155.0 (C-12′), 151.1 (C-6), 148.2 (C-6′), 147.0 (C-12), 144.9 (C-8), 143.4 (C-11), 140.9 (C-7′), 134.7 (C-3′′), 134.1 (C-3′′′), 133.2 (C-2′′, 5′′, 2′′′), 133.2 (C-9′), 132.8 (C-5′′′), 132.4 (C-9), 132.3 (C-10′), 131.2 (C-7), 129.5 (C-14′), 127.8 (C-4a′, 8a′), 127.6 (C-4′′), 127.5 (C-4′′′), 125.6 (C-14), 124.4 (C-4a, 8a), 122.7 (C-10, 13), 117.8 (C-8′), 115.2 (C-11′), 113.4 (C-13′), 111.8 (C-5′), 109.0 (C-5), 65.3 (C-1′), 60.8 (C-1), 56.1 (6-O C H 3 ), 55.1 (6′-O C H 3 ), 45.9 (C-3′), 43.4 (C-3), 42.4 (N′- C H 3 ), 41.6 (N- C H 3 ), 40.3 (C- α′), 39.3 (C-α), 25.5 (C-4′), 22.0 (C-4); HR-TOF-MS (ESI + ): m/z 815.2452 [M + H] + (calcd. for C 46 H 43 N 2 O 8 S 2 , 815.2452). Preparation of Compound 6 A mixture of compound 1 (100 mg, 0.17 mmol) was dissolved in CH 2 Cl 2 (10 ml) and N,N׳-diisopropylcarbodiimide (DIC) (0.1 ml), 4-N,N׳-dimethylaminopyridine (DMAP) (1 mg, 0.01 mmol) and 4-Chlorocinamic acid (10 mg, 0.05 mmol) was stirred at room temperature for 96 h. The mixture was poured into water (30 ml) and the solution was extracted with CH 2 Cl 2 (100 ml). The organic phase was washed with water (3×20 ml) and dried over anhydrous Na 2 SO 4 . The solvent was removed under reduced pressure, and the product was purified by column chromatography using 4% MeOH in CH 2 Cl 2 , yielding compound 6 (47.1 mg, 35.2%). 7-(4-Chlorocinamoyl)-curine (6) Pale yellow powder; \({\text{[α]}}_{\text{D}}^{\text{27}}\) -208.18 ( c = 0.32, CH 2 Cl 2 ); IR ν max : 2930, 2840, 1734, 1635, 1609, 1504, 1444, 1272, 1207, 1111, 1089, 820, 727 cm − 1 ; 1 H NMR (CDCl 3 , 400 MHz,): δ 7.57 (1H, br d, J = 15.8 Hz, H-7′′), 7.37 (1H, d, J = 7.6 Hz, H-2′′,6′′), 7.31 (1H, d, J = 7.6 Hz, H-3′′,5′′), 7.06 (1H, d, J = 7.6 Hz, H-14′), 6.92 (1H, d, J = 7.6 Hz, H-14), 6.79 (1H, d, J = 7.6 Hz, H-13), 6.72 (1H, d, J = 7.6 Hz, H-13′), 6.67 (1H, br s, H-5′), 6.64 (2H, overlapping signal, H-5, H-10), 6.61 (1H, overlapping signal, H-11′), 6.46 (1H, br d, J = 15.8 Hz, H-8′′), 6.45 (1H, overlapping signal, H-10′), 5.94 (1H, s, H-8′), 3.88 (3H, s, 6′-OCH 3 ), 3.84 (3H, s, 6-OCH 3 ), 3.54 (1H, d, J = 7.6 Hz, H-1), 3.43 (1H, d, J = 10.4 Hz, H-1′), 3.35 (1H, m, H-3), 3.21 (1H, m, H-3′), 3.16 (1H, br d, J = 13.2 Hz, H-α′), 3.02 (1H, m, H-4), 2.90, 2.75 (2H, overlapping signal, H-4′), 2.88 (1H, overlapping signal, H-3), 2.79 (3H, overlapping signal, H-α, 3′), 2.57 (1H, overlapping signal, H-α′), 2.51 (1H, overlapping signal, H-4), 2.51 (3H, s, N′-CH 3 ), 2.27 (3H, s, N-CH 3 ); 13 C NMR (CDCl 3 , 100 MHz,): δ 164.2 (C-9′′), 155.4 (C-12′), 150.8 (C-6), 148.6 (C-6′), 146.4 (C-12), 145.1 (C-7′′), 144.7 (C-8), 144.1 (C-11), 143.3 (C-7′), 136.4 (C-4′′), 133.6 (C-9), 133.1 (C-1′′), 132.6 (C-9′), 132.5 (C-10′), 131.6 (C-7), 129.6 (C-14′), 129.4 (C-2′′, C-6′′), 129.2 (C-3′′, C-5′′), 129.1 (C-4a′, C-8a′), 126.7 (C-14), 124.4 (C-4a, C-8a), 120.9 (C-10), 119.9 (C-8′), 117.0 (C-8′′), 115.7 (C-11′), 115.3 (C-13), 113.9 (C-13′), 112.3 (C-5′), 108.9 (C-5), 65.5 (C-1′), 60.3 (C-1), 56.1 (6-O C H 3 ), 56.0 (6′-O C H 3 ), 45.9 (C-3′), 43.6 (C-3), 42.3 (N′- C H 3 ), 41.7 (N- C H 3 ), 39.7 (C-α, α′), 25.5 (C-4′), 22.2 (C-4); HR-TOF-MS (ESI + ): m/z 759.2820 [M + H] + (calcd. for C 45 H 44 ClN 2 O 7 , 759.2932). Preparation of Compound 7 A mixture of compound 1 (100 mg, 0.17 mmol) was dissolved in CH 2 Cl 2 (10 ml) and N,N׳-diisopropylcarbodiimide (DIC) (0.1 ml), 4-N,N׳-dimethylaminopyridine (DMAP) (1 mg, 0.01 mmol) and 3-Nitrobenzoic acid (10 mg, 0.06 mmol) was stirred at room temperature for 6 h. Subsequently, the mixture was poured into water (30 ml) and extracted with CH 2 Cl 2 (100 ml). The organic phase was washed with water (3×20 ml) and dried over anhydrous Na 2 SO 4 . The solvent was removed under reduced pressure and the product was purified by column chromatography using 4% MeOH in CH 2 Cl 2 to yield compound 7 (31.3 mg, 20.2%). 7,12-di-(3-nitrobenzoyl)-curine (7) Pale yellow powder; \({\text{[α]}}_{\text{D}}^{\text{27}}\) -219.13 ( c = 0.30, CH 2 Cl 2 ); IR ν max : 2933, 1747, 1612, 1530, 1503, 1435, 1348, 1252, 1205, 1110, 1050, 908, 816, 714 cm − 1 ; 1 H NMR (CDCl 3 , 400 MHz,): δ 8.71 (1H, s, H-2′′′), 8.65 (1H, s, H-2′′), 8.38 (1H, d, J = 8.0 Hz, H-4′′′), 8.36 (1H, d, J = 7.2 Hz, H-4′′), 8.32 (1H, d, J = 8.0 Hz, H-6′′′), 8.22 (1H, d, J = 8.0 Hz, H-6′′), 7.60 (1H, t, J = 8.0 Hz, H-5′′′), 7.55 (1H, t, J = 8.0 Hz, H-5′′), 7.27 (1H, overlapping signal, H-14), 7.09 (1H, d, J = 8.0 Hz, H-13), 7.01 (1H, d, J = 8.0 Hz, H-14′), 6.78 (1H, overlapping signal, H-11′), 6.67 (1H, s, H-5), 6.67 (1H, overlapping signal, H-13′), 6.62 (1H, br s, H-10), 6.47 (1H, d, J = 8.0 Hz, H-10′), 6.53 (1H, br s, H-5′), 5.52 (1H, s, H-8′), 3.82 (3H, s, 6-OCH 3 ), 3.62 (1H, d, J = 8.0 Hz, H-1), 3.52 (1H, br s, H-1′), 3.41, 2.94 (2H, overlapping signal, H-3), 3.37 (3H, s, 6′-OCH 3 ), 3.22, 2.85 (2H, m, H-3′), 3.22, 2.54 (2H, overlapping signal, H-α), 3.10 (1H, m, H-4), 2.94, 2.78 (2H, overlapping signal, H- α′), 2.94, 2.73 (2H, overlapping signal, H-4′), 2.87, 2.72 (2H, d, J = 15.2 Hz, H- 4′), 2.50 (1H, overlapping signal, H-4), 2.50 (3H, s, N′-CH 3 ), 2.35 (3H, s, N-CH 3 ); 13 C NMR (CDCl 3 , 100 MHz,): δ 162.4 (C-7′′′), 162.1 (C-7′′), 155.1 (C-12′), 150.8 (C-6), 148.3 (C-6′), 148.1 (C-3′′, C-3′′′), 146.8 (C-12), 144.6 (C-8), 143.2 (C-7′), 141.3 (C-11), 139.9 (C-9), 135.7 (C-6′′, C-6′′′), 133.6 (C-9′), 132.3 (C-10′), 131.4 (C-1′′′), 130.9 (C-1′′), 130.7 (C-7), 129.7 (C-14′), 129.5 (C-5′′, C-5′′′), 128.7 (C-4a′), 127.7 (C-4′′′), 127.5 (C-4′′, C-8a′), 125.4 (C-14), 125.1 (C-2′′′), 124.9 (C-2′′), 124.6 (C-4a, C-8a), 122.5 (C-13), 122.2 (C-10), 118.3 (C-8′), 115.0 (C-11′), 114.3 (C-13′), 112.0 (C-5′), 109.0 (C-5), 64.9 (C-1′), 60.6 (C-1), 56.1 (6-O C H 3 ), 55.2 (6′-O C H 3 ), 45.5 (C-3′), 43.4 (C-3), 41.9 (N′- C H 3 ), 41.7 (N- C H 3 ), 40.6 (C-α), 39.2 (C- α′), 25.0 (C-4′), 22.0 (C-4); HR-TOF-MS (ESI + ): m/z 893.3039 [M + H] + (calcd. for C 50 H 45 N 4 O 12 , 893.3028). Preparation of Compound 8 A mixture of compound 1 (100 mg, 0.17 mmol) was dissolved in CH 2 Cl 2 (10 ml) and N,N׳-diisopropylcarbodiimide (DIC) (0.1 ml), 4-N,N′-dimethylaminopyridine (DMAP) (1 mg, 0.01 mmol) and trans -3-Nitrocinamic acid (10 mg, 0.05 mmol) was stirred at room temperature for 6 h. The mixture was poured into water (30 ml) and the solution was extracted with CH 2 Cl 2 (100 ml). The organic phase was washed with water (3×20 ml) and dried over anhydrous Na 2 SO 4 . The solvent was removed under reduced pressure and the product was purified by column chromatography using 4% MeOH in CH 2 Cl 2 to yield compound 8 (72.4 mg, 47%). 7,12-di-(trans-3-nitrocinamoyl)-curine (8) Pale yellow powder; \({\text{[α]}}_{\text{D}}^{\text{27}}\) -141.40 ( c = 0.30, CH 2 Cl 2 ); IR ν max : 2931, 2845, 1735, 1640, 1610, 1503, 1350, 1268, 1196, 1112, 974, 805, 740 cm − 1 ; 1 H NMR (CDCl 3 , 400 MHz,): δ 8.28 (1H, s, H-2′′), 8.21 (1H, s, H-2′′′), 8.19 (1H, d, J = 8.0 Hz, H-4′′), 8.18 (1H, d, J = 8.0 Hz, H-4′′′), 7.78 (1H, d, J = 7.9 Hz, H-6′′), 7.70 (1H, d, J = 7.9 Hz, H-6′′′), 7.61 (1H, br d, J = 16.4 Hz, H-7′′), 7.55 (1H, t, J = 7.9 Hz, H-5′′), 7.54 (1H, d, J = 7.9 Hz, H-5′′′), 7.45 (1H, overlapping signal, H-7′′′), 7.20 (1H, d, J = 8.0 Hz, H-14), 7.04 (1H, d, J = 8.0 Hz, H-13), 7.01 (1H, d, J = 8.0 Hz, H-14′), 6.69 (1H, d, J = 9.2 Hz, H-11′), 6.66 (1H, s, H-5), 6.64 (3H, overlapping signal, H-10, H-8′′, H-8′′′), 6.58 (2H, overlapping signal, H-5′, H-13′), 6.48 (1H, d, J = 7.2 Hz, H-10′), 5.54 (1H, s, H-8′), 3.82 (3H, s, 6-OCH 3 ), 3.63 (1H, overlapping signal, H-1), 3.63 (3H, s, 6′-OCH 3 ), 3.46 (1H, d, J = 10.0 Hz, H-1′), 3.36 (1H, m, H-3), 3.23 (1H, m, H-3′), 3.13 (1H, br d, J = 11.2 Hz, H-α′), 3.04 (1H, m, H-4), 2.93 (1H, overlapping signal, H-3), 2.91, 2.72 (2H, overlapping signal, H-4′), 2.90 (1H, overlapping signal, H-α), 2.82 (1H, d, J = 10.0 Hz, H-3′), 2.72, 2.51 (2H, overlapping signal, H-4), 2.67 (1H, d, J = 13.6 Hz, H-α), 2.58 (1H, br d, J = 11.6 Hz, H-α′), 2.48 (3H, s, N′-CH 3 ), 2.32 (3H, s, N-CH 3 ); 13 C NMR (CDCl 3 , 100 MHz,): δ 2.58 (1H, br d, J = 11.6 Hz, H-α′), 2.48 (3H, s, N′-CH 3 ), 2.32 (3H, s, N-CH 3 ); 13 C NMR (CDCl 3 , 100 MHz,): δ 163.8 (C-9′′′), 163.3 (C-9′′), 155.2 (C-12′), 150.8 (C-6), 148.6 (C-6′, C-3′′, C-3′′′), 146.7 (C-12), 144.6 (C-8), 143.4 (C-7′′′), 143.2 (C-7′), 142.7 (C-7′′), 140.9 (C-9), 139.9 (C-11), 136.0 (C-1′′), 135.9 (C-1′′′), 133.5 (C-6′′, C-6′′′), 133.1 (C-9′), 132.2 (C-10′, C-7), 130.0 (C-5′′′), 129.9 (C-14′), 129.6 (C-5′′), 127.9 (C-4a′, C-8a′), 125.2 (C-14), 124.7 (C-4′′, C-4′′′), 124.5 (C-4a, C-8a), 122.7 (C-13), 122.5 (C-2′′, C-2′′′), 121.9 (C-8′′, C-8′′′), 120.4 (C-10), 119.6 (C-13′), 118.2 (C-8′), 115.1 (C-11′), 112.2 (C-5′), 108.9 (C-5), 64.9 (C-1′), 60.5 (C-1), 56.1 (6′-O C H 3 ), 55.8 (6-O C H 3 ), 45.6 (C-3′), 43.4 (C-3), 42.1 (N′- C H 3 ), 41.6 (N- C H 3 ), 40.4 (C-α), 38.6 (C- α′), 25.3 (C-4′), 22.0 (C-4); HR-TOF-MS (ESI + ): m/z 945.3359 [M + H] + (calcd. for C 54 H 49 N 4 O 12 , 945.3341). Cell lines and culture Cell lines were cultured as previously reported [ 10 ]. Briefly, MCF-7, MDA-MB-231, Huh-7, and human embryonic kidney 293T (HEK293T) cells were cultured in Dulbecco's Modified Eagle's medium and Ham's F-12 nutrient mixture (DMEM/F12; Gibco, Thermo Fisher Scientific) with 10% fetal bovine serum (FBS; Gibco, Thermo Fisher Scientific), 100 units/ml penicillin and 100 µg/mL streptomycin at 37 ◦C under a humidified 5% CO 2 atmosphere. The cells were sub-cultured twice per week by following the standard trypsinization protocol. Cytotoxicity assay Cell lines at a density 5x10 3 cells/well were seeded in a 96-well plate for 24 h. Various test compound concentrations were added to the 96-well plate and incubated for 24 hours. Ten microliters of MTT solution (5 mg/ml) were added and incubated for 2 h. Then, cell supernatants were removed, and DMSO was added to dissolve the formazan product. A microplate spectrophotometer measured light absorbent at 570 nm. The IC 50 was calculated by using GraphPad Prism version 8. Cisplatin (Sigma) and 0.75% DMSO (RCI Labscan) were used as a positive and negative control. Declarations Conflict of interest: The authors declare no competing interests. Acknowledgments We acknowledge financial support from College of Allied Health Sciences, Suan Sunandha Rajabhat University. Partial support from the Center of Excellence for Innovation in Chemistry (PERCH-CIC) are gratefully acknowledged. References Rukachaisirikul T, Kumjun S, Suebsakwong P, Apiratikul N, Suksamrarna A (2019) A new pyrrole alkaloid from the roots of Cissampelos pareira . Nat Prod Res 35:80–87. https://doi.org/10.1080/14786419.2019.1614576 Medeiros MAA, Pinho JF, De-Lira DP, Barbosa-Filho JM, Araújo DAM, Cortes SF, Lemos VS, Cruz JS (2011) Curine, a bisbenzylisoquinoline alkaloid, blocks L-type Ca 2+ channels and decreases intracellular Ca 2+ transients in A7r5 cells. Eur J Pharmacol 669:100–107. https://doi.org/10.1016/j.ejphar.2011.07.044 Leite FC, Ribeiro-Filho J, Costa HF, Salgado PRR, Calheiros AS, Carneiro AB, Almeida RN, Dias CS, Bozza PT, Piuvezam MR (2014) Curine, an alkaloid Isolated from Chondrodendron platyphyllum inhibits prostaglandin E2 in experimental models of inflammation and pain. Planta Med 80:1072–1078. https://doi.org/10.1055/s-0034-1382997 Ribeiro-Filho J, Piuvezam MR, Bozza PT (2015) Anti-allergic properties of curine, a bisbenzylisoquinoline alkaloid. Molecules 20:4695–4697. https://doi:10.3390/molecules20034695 Ribeiro-Filho J, Leite FC, Costa HF, Calheiros AS, Torres RC, Azevedo CT, Martins MA, Dias CS, Bozza PT, Piuvezam MR (2014) Curine inhibits mast cell-dependent responses in mice. J Ethnopharmacol 155:1118–1124. https://doi.org/10.1016/j.jep.2014.06.041 Ribeiro-Filho J, Calheiros AS, Vieira-de-Abreu A, Carvalho KIM, Mendes DS, Melo CB, Martins MA, Dias CS, Piuvezam MR, Bozza PT (2013) Curine inhibits eosinophil activation and airway hyper-responsiveness in a mouse model of allergic asthma. Toxicol Appl Pharmacol 273:19–26. https://doi.org/10.1016/j.taap.2013.08.015 Gong S, Xu D, Zou F, Peng R (2017) (–)-Curine induces cell cycle arrest and cell death in hepatocellular carcinoma cells in a p53-independent way. Biomed Pharmacother 89:894–801. http://dx.doi.org/10.1016/j.biopha.2017.01.148 Dantas BB, Faheina-Martins GV, Coulidiati TH, Bomfim CCB, Dias CS, Barbosa-Filho JMB, Araújo DAM (2015) J Nat Med 69:218–223. https://doi.org/10.1007/s11418-014-0881-5 Koike L, Marsaioli AJ, Reis FAM (1981) Proton and carbon-13 nuclear magnetic resonance spectroscopy and conformational aspects of the curine class of bis(benzylisoquinoline) alkaloids. J Org Chem 46:2385–2389. https://doi.org/10.1021/jo00324a036 Chokchaisiri R, Chaichompoo W, Bureekaew S, Thepmalee C, Ganranoo L, Cheenpracha S, Suksamrarn A (2024) A new oligostilbenoid isolated from the stems of Ochna integerrima . Phytochem Lett 59:41–44. https://doi.org/10.1016/j.phytol.2023.12.001 Scheme Schemes 1 and 2 are available in the Supplementary Files section Supplementary Files Scheme12.docx Supplementaryinformation.docx Cite Share Download PDF Status: Posted Version 1 posted You are reading this latest preprint version Research Square lets you share your work early, gain feedback from the community, and start making changes to your manuscript prior to peer review in a journal. As a division of Research Square Company, we’re committed to making research communication faster, fairer, and more useful. We do this by developing innovative software and high quality services for the global research community. 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Also discoverable on Platform About Our Team In Review Editorial Policies Advisory Board Help Center Resources Author Services Accessibility API Access RSS feed Manage Cookie Preferences © Research Square 2026 | ISSN 2693-5015 (online) Privacy Policy Terms of Service Do Not Sell My Personal Information {"props":{"pageProps":{"initialData":{"identity":"rs-4140864","acceptedTermsAndConditions":true,"allowDirectSubmit":true,"archivedVersions":[],"articleType":"Research Article","associatedPublications":[],"authors":[{"id":285451650,"identity":"76e151e9-85e5-4208-930e-470500f0237c","order_by":0,"name":"Suwadee Chokchaisiri","email":"data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAAZAAAAAyAQMAAABI0h/eAAAABlBMVEX///8AAABVwtN+AAAACXBIWXMAAA7EAAAOxAGVKw4bAAAA3klEQVRIiWNgGAWjYLACHhAhwXwALsBMpBa2BBifsZlILTwGxGmRn5Fj+OFNhQ0D/+yezx9/7jnMwN9+gP1xAR4tBjdyjCXnnEljkLhzdps0z7PDDBJnEhibZ+DTIpG7QZq37TCIsY2Z4cBhBoYbQIfx4HVY7ubfvP/+A7XkPP74A6hFnpAWhhu526R5Gw6AtABDAKjFgJAWgzPvv1nOOZbMI3EjzUya50A6j+GZxMbZeB3WnpZ8402NnRz/jGSQw6zl5I4fPvAZr8OggAeJwdhAhIZRMApGwSgYBfgAADFUSnS+KxZ3AAAAAElFTkSuQmCC","orcid":"","institution":"Suan Sunandha Rajabhat University","correspondingAuthor":true,"prefix":"","firstName":"Suwadee","middleName":"","lastName":"Chokchaisiri","suffix":""},{"id":285451651,"identity":"7e59b5e6-7d7a-41b3-a808-1d98178f1291","order_by":1,"name":"Sittisak Kumjun","email":"","orcid":"","institution":"RU: Ramkhamhaeng University","correspondingAuthor":false,"prefix":"","firstName":"Sittisak","middleName":"","lastName":"Kumjun","suffix":""},{"id":285451652,"identity":"7dac0a7c-47fb-40ad-9736-c17e3d7debc7","order_by":2,"name":"Chutamas Thepmalee","email":"","orcid":"","institution":"PYO: University of Phayao","correspondingAuthor":false,"prefix":"","firstName":"Chutamas","middleName":"","lastName":"Thepmalee","suffix":""},{"id":285451653,"identity":"21df4a39-6d55-4ebf-9201-cd0e91acfb8d","order_by":3,"name":"Thitima Rukachaisirikul","email":"","orcid":"","institution":"RU: Ramkhamhaeng University","correspondingAuthor":false,"prefix":"","firstName":"Thitima","middleName":"","lastName":"Rukachaisirikul","suffix":""}],"badges":[],"createdAt":"2024-03-21 05:27:28","currentVersionCode":1,"declarations":"","doi":"10.21203/rs.3.rs-4140864/v1","doiUrl":"https://doi.org/10.21203/rs.3.rs-4140864/v1","draftVersion":[],"editorialEvents":[],"editorialNote":"","failedWorkflow":false,"files":[{"id":57714794,"identity":"03cb90a3-3103-4ae6-b0f5-b1399e690307","added_by":"auto","created_at":"2024-06-04 16:46:55","extension":"pdf","order_by":0,"title":"","display":"","copyAsset":false,"role":"manuscript-pdf","size":702797,"visible":true,"origin":"","legend":"","description":"","filename":"manuscript.pdf","url":"https://assets-eu.researchsquare.com/files/rs-4140864/v1/68d8a22e-af4c-4823-90bc-f47aa2e70494.pdf"},{"id":54012231,"identity":"a2de92be-75cd-4c9a-b253-63d27889939a","added_by":"auto","created_at":"2024-04-03 11:10:18","extension":"docx","order_by":2,"title":"","display":"","copyAsset":false,"role":"supplement","size":200406,"visible":true,"origin":"","legend":"","description":"","filename":"Scheme12.docx","url":"https://assets-eu.researchsquare.com/files/rs-4140864/v1/590c009445921283a91ff853.docx"},{"id":54012232,"identity":"375a54fa-996b-4f11-aae5-c362d0db3ca3","added_by":"auto","created_at":"2024-04-03 11:10:18","extension":"docx","order_by":8,"title":"","display":"","copyAsset":false,"role":"supplement","size":6017122,"visible":true,"origin":"","legend":"","description":"","filename":"Supplementaryinformation.docx","url":"https://assets-eu.researchsquare.com/files/rs-4140864/v1/2afba3b35eb0273aa436d6f4.docx"}],"financialInterests":"","formattedTitle":"Synthesis and cytotoxic evaluation of ester analogues of (-)-curine","fulltext":[{"header":"Introduction","content":"\u003cp\u003e(-)-Curine, a bisbenzylisoquinoline (BBIQ) alkaloid, is the primary compound derived from the methanol extract of \u003cem\u003eCissampelos pareira\u003c/em\u003e roots. This plant, known for its diverse medicinal properties, has been historically used in traditional medicine to address a spectrum of ailments, including coughs, delirium, fever, madness, epilepsy, and convulsions [\u003cspan citationid=\"CR1\" class=\"CitationRef\"\u003e1\u003c/span\u003e]. Its global application extends to serving as a stimulant, sedative, analgesic, febrifuge, antioxidant, tonic, and narcotic agent [\u003cspan citationid=\"CR1\" class=\"CitationRef\"\u003e1\u003c/span\u003e]. The pharmacological potential of curine has attracted scientific interest, with earlier investigations uncovering its vasodilator effects attributed to the inhibition of calcium influx, possibly mediated by the direct blockade of L-type Ca\u003csup\u003e2+\u003c/sup\u003e channels [\u003cspan citationid=\"CR2\" class=\"CitationRef\"\u003e2\u003c/span\u003e]. Additionally, curine has exhibited anti-inflammatory effects [\u003cspan citationid=\"CR3\" class=\"CitationRef\"\u003e3\u003c/span\u003e], anti-allergic properties [\u003cspan additionalcitationids=\"CR5\" citationid=\"CR4\" class=\"CitationRef\"\u003e4\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR6\" class=\"CitationRef\"\u003e6\u003c/span\u003e] and cytotoxicity [\u003cspan citationid=\"CR7\" class=\"CitationRef\"\u003e7\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR8\" class=\"CitationRef\"\u003e8\u003c/span\u003e], suggesting its broad spectrum of biological activities. Despite its promising pharmacological profile, the chemical modification of curine has emerged as a strategy to enhance its therapeutic efficacy and selectivity. Chemical modification of natural compounds is a prevailing approach in medicinal chemistry aimed at developing more potent pharmacological agents. By employing straightforward synthetic methodologies, the production of modified curine analogs with robust bioactivity becomes feasible, thus presenting opportunities for the pharmaceutical industry. The current study focuses on the chemical modification of curine (\u003cb\u003e1\u003c/b\u003e) to synthesize analogs (Scheme \u003cspan refid=\"Sch1\" class=\"InternalRef\"\u003e1\u003c/span\u003e\u0026ndash;\u003cspan refid=\"Sch2\" class=\"InternalRef\"\u003e2\u003c/span\u003e), with some exhibiting notable cytotoxic activities. This approach underscores the importance of structural manipulation in elucidating structure-activity relationships and enhancing the pharmacological properties of natural compounds like curine.\u003c/p\u003e"},{"header":"Results and discussion","content":"\u003cdiv id=\"Sec3\" class=\"Section2\"\u003e \u003ch2\u003eChemistry\u003c/h2\u003e \u003cp\u003eThe chemical modifications described in this study focus on the ester analogues at the C-7 and C-12 hydroxyl groups of (-)-curine (\u003cb\u003e1\u003c/b\u003e). The first series of ester-(-)-curine (\u003cb\u003e1\u003c/b\u003e) analogues were prepared as shown in Scheme \u003cspan refid=\"Sch1\" class=\"InternalRef\"\u003e1\u003c/span\u003e. Acetylation of the resulting (-)-curine (\u003cb\u003e1\u003c/b\u003e) at C-7 and C-12 in the presence of acetic anhydride at room temperature for 3 h afforded the mono- and di-acetylcurine products 7,12-Diacetoxylcurine (\u003cb\u003e2\u003c/b\u003e) and 7-Acetoxylcurine (\u003cb\u003e3\u003c/b\u003e).\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003cp\u003eCompound \u003cb\u003e4\u003c/b\u003e, 7-(1,6-dihydrocyclopenta[c]pyrazole-3-carboxyl)-curine, was synthesized by reacting compound \u003cb\u003e1\u003c/b\u003e with 1,6-dihydrocyclopenta[c]pyrazole-3-carboxylic acid, N,N'-diisopropylcarbodiimide (DIC), in dichloromethane, employing 4-\u003cem\u003eN\u003c/em\u003e,\u003cem\u003eN\u003c/em\u003e-dimethylaminopyridine (DMAP) as a catalyst, resulting in a yield of 35.3% (Scheme \u003cspan refid=\"Sch2\" class=\"InternalRef\"\u003e2\u003c/span\u003e). 7,12-Dithiophene-2-carbonylcurine (\u003cb\u003e5\u003c/b\u003e) was obtained in excellent yield (94.1%) through the reaction of compound \u003cb\u003e1\u003c/b\u003e with thiophene-2-carbonyl chloride, DIC, in dichloromethane, with DMAP serving as the catalyst (Scheme \u003cspan refid=\"Sch2\" class=\"InternalRef\"\u003e2\u003c/span\u003e). The synthesis of 7-(4-Chlorocinamoyl)-curine (\u003cb\u003e6\u003c/b\u003e) involved the reaction of compound \u003cb\u003e1\u003c/b\u003e with 4-chlorocinamic acid, DIC, in dichloromethane, facilitated by DMAP, resulting in a yield of 35.2% (Scheme \u003cspan refid=\"Sch2\" class=\"InternalRef\"\u003e2\u003c/span\u003e). 7,12-di-(3-nitrobenzoyl)-curine (\u003cb\u003e7\u003c/b\u003e) was obtained by reacting compound \u003cb\u003e1\u003c/b\u003e with 3-nitrobenzoic acid, DIC, in dichloromethane in the presence of DMAP, yielding 20.2% (Scheme \u003cspan refid=\"Sch2\" class=\"InternalRef\"\u003e2\u003c/span\u003e). The preparation of 7,12-di-(trans-3-nitrocinamoyl)-curine (\u003cb\u003e8\u003c/b\u003e) involved the reaction of compound \u003cb\u003e1\u003c/b\u003e with trans-3-nitrocinamic acid, DIC, in dichloromethane, using DMAP as the catalyst, resulting in a yield of 47.0% (Scheme \u003cspan refid=\"Sch2\" class=\"InternalRef\"\u003e2\u003c/span\u003e). All synthetic compounds were purified by column chromatography and characterized by spectroscopic techniques and high-resolution mass spectrometry (see Experimental).\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003c/div\u003e\n\u003ch3\u003eCytotoxic evaluation of (-)-curine and its analogs against cancer cell lines\u003c/h3\u003e\n\u003cp\u003eThe cytotoxic activities of (-)-curine (compound \u003cb\u003e1\u003c/b\u003e) and its analogs (\u003cb\u003e2\u0026ndash;8\u003c/b\u003e), alongside the positive control cisplatin, were evaluated against triple-negative breast cancer (MDA-MB231), hepatocellular carcinoma (Huh-7), human breast cancer (MCF-7), and non-cancerous human embryonic kidney 293T cells (HEK293T), utilizing the MTT assay, as depicted in Table\u0026nbsp;\u003cspan refid=\"Tab1\" class=\"InternalRef\"\u003e1\u003c/span\u003e. Compounds \u003cb\u003e1\u003c/b\u003e, \u003cb\u003e2\u003c/b\u003e, \u003cb\u003e3\u003c/b\u003e, \u003cb\u003e6\u003c/b\u003e, \u003cb\u003e7\u003c/b\u003e, and \u003cb\u003e8\u003c/b\u003e demonstrated IC\u003csub\u003e50\u003c/sub\u003e values greater than 100 \u0026micro;M across all cell lines, indicating minimal cytotoxic effects within the tested concentration range. Conversely, compounds \u003cb\u003e4\u003c/b\u003e and \u003cb\u003e5\u003c/b\u003e exhibited varying degrees of cytotoxicity against the cell lines. Compound \u003cb\u003e4\u003c/b\u003e displayed IC\u003csub\u003e50\u003c/sub\u003e values of 57.52\u0026thinsp;\u0026plusmn;\u0026thinsp;1.20 \u0026micro;M, 37.44\u0026thinsp;\u0026plusmn;\u0026thinsp;1.87 \u0026micro;M, and 45.33\u0026thinsp;\u0026plusmn;\u0026thinsp;1.96 \u0026micro;M against MDA-MB-231, Huh-7, and MCF-7 cells, respectively, while showing no significant effect on HEK-293T cells (\u0026gt;\u0026thinsp;100 \u0026micro;M). Compound \u003cb\u003e5\u003c/b\u003e demonstrated similar potency, with IC\u003csub\u003e50\u003c/sub\u003e values of 58.97\u0026thinsp;\u0026plusmn;\u0026thinsp;3.07 \u0026micro;M, 33.00\u0026thinsp;\u0026plusmn;\u0026thinsp;1.82 \u0026micro;M, and 23.33\u0026thinsp;\u0026plusmn;\u0026thinsp;1.67 \u0026micro;M against MDA-MB-231, Huh-7, and MCF-7 cells, respectively, and 58.84\u0026thinsp;\u0026plusmn;\u0026thinsp;3.06 \u0026micro;M against HEK-293T cells. Notably, compounds \u003cb\u003e4\u003c/b\u003e and \u003cb\u003e5\u003c/b\u003e exhibited comparable or superior cytotoxic effects against the tested cancer cell lines compared to the positive control cisplatin, indicating their potential as promising candidates for further investigation as cytotoxic agents. These findings suggest the importance of exploring structural modifications to enhance the pharmacological properties of (-)-curine and its analogs, potentially leading to the development of novel anticancer therapeutics.\u003c/p\u003e \u003cp\u003e \u003cdiv class=\"gridtable\"\u003e\u003ctable float=\"Yes\" id=\"Tab1\" border=\"1\"\u003e \u003ccaption language=\"En\"\u003e \u003cdiv class=\"CaptionNumber\"\u003eTable 1\u003c/div\u003e \u003cdiv class=\"CaptionContent\"\u003e \u003cp\u003eCytotoxic activities of compounds \u003cb\u003e1\u003c/b\u003e\u0026minus;\u003cb\u003e8\u003c/b\u003e\u003c/p\u003e \u003c/div\u003e \u003c/caption\u003e \u003ccolgroup cols=\"5\"\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 \u003cdiv align=\"left\" class=\"colspec\" colname=\"c5\" colnum=\"5\"\u003e\u003c/div\u003e \u003cthead\u003e \u003ctr\u003e \u003cth align=\"left\" colname=\"c1\" morerows=\"1\" rowspan=\"2\"\u003e \u003cp\u003eCompound\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colspan=\"3\" nameend=\"c4\" namest=\"c2\"\u003e \u003cp\u003eCytotoxicity (IC\u003csub\u003e50\u003c/sub\u003e, \u003cem\u003e\u0026micro;\u003c/em\u003eM)\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c5\"\u003e\u0026nbsp;\u003c/th\u003e \u003c/tr\u003e \u003ctr\u003e \u003cth align=\"left\" colname=\"c2\"\u003e \u003cp\u003eMDA-MB-231\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c3\"\u003e \u003cp\u003eHuh-7\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c4\"\u003e \u003cp\u003eMCF-7\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c5\"\u003e \u003cp\u003eHEK-293T\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\u003e1\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e\u0026gt;\u0026thinsp;100\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e\u0026gt;\u0026thinsp;100\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e\u0026gt;\u0026thinsp;100\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e\u0026gt;\u0026thinsp;100\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cb\u003e2\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e\u0026gt;\u0026thinsp;100\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e\u0026gt;\u0026thinsp;100\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e\u0026gt;\u0026thinsp;100\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e\u0026gt;\u0026thinsp;100\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cb\u003e3\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e\u0026gt;\u0026thinsp;100\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e\u0026gt;\u0026thinsp;100\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e\u0026gt;\u0026thinsp;100\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e\u0026gt;\u0026thinsp;100\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cb\u003e4\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e57.52\u0026thinsp;\u0026plusmn;\u0026thinsp;1.20\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e37.44\u0026thinsp;\u0026plusmn;\u0026thinsp;1.87\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e45.33\u0026thinsp;\u0026plusmn;\u0026thinsp;1.96\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e\u0026gt;\u0026thinsp;100\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cb\u003e5\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e58.97\u0026thinsp;\u0026plusmn;\u0026thinsp;3.07\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e33.00\u0026thinsp;\u0026plusmn;\u0026thinsp;1.82\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e23.33\u0026thinsp;\u0026plusmn;\u0026thinsp;1.67\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e58.84\u0026thinsp;\u0026plusmn;\u0026thinsp;3.06\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cb\u003e6\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e\u0026gt;\u0026thinsp;100\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e\u0026gt;\u0026thinsp;100\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e\u0026gt;\u0026thinsp;100\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e\u0026gt;\u0026thinsp;100\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cb\u003e7\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e\u0026gt;\u0026thinsp;100\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e\u0026gt;\u0026thinsp;100\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e\u0026gt;\u0026thinsp;100\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e\u0026gt;\u0026thinsp;100\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cb\u003e8\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e\u0026gt;\u0026thinsp;100\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e\u0026gt;\u0026thinsp;100\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e\u0026gt;\u0026thinsp;100\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e\u0026gt;\u0026thinsp;100\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cb\u003eCisplatin\u003c/b\u003e \u003csup\u003e\u003cb\u003ea\u003c/b\u003e\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e28.42\u0026thinsp;\u0026plusmn;\u0026thinsp;1.73\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e46.54\u0026thinsp;\u0026plusmn;\u0026thinsp;2.89\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e37.55\u0026thinsp;\u0026plusmn;\u0026thinsp;1.81\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e60.22\u0026thinsp;\u0026plusmn;\u0026thinsp;3.08\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003c/tbody\u003e \u003c/colgroup\u003e \u003ctfoot\u003e \u003ctr\u003e\u003ctd colspan=\"5\"\u003e\u003csup\u003ea\u003c/sup\u003ePositive control\u003c/td\u003e\u003c/tr\u003e \u003c/tfoot\u003e \u003c/table\u003e\u003c/div\u003e \u003c/p\u003e"},{"header":"Conclusion","content":"\u003cp\u003eIn conclusion, the study focused on the chemical modification of (-)-curine, a bisbenzylisoquinoline alkaloid derived from the roots of \u003cem\u003eCissampelos pareira\u003c/em\u003e, aiming to synthesize analogs with enhanced pharmacological properties, particularly cytotoxicity against various cancer cell lines. The synthesis of seven ester analogs of (-)-curine was successfully achieved through straightforward synthetic methodologies involving esterification reactions with different carboxylic acids. The compounds were purified and characterized using spectroscopic techniques and high-resolution mass spectrometry. Evaluation of cytotoxic potential across multiple cancer cell lines revealed compounds \u003cb\u003e4\u003c/b\u003e and \u003cb\u003e5\u003c/b\u003e to exhibit significant activity, surpassing (-)-curine and matching or exceeding cisplatin's effects. These results highlight the potential of chemical modification strategies to enhance natural compounds' pharmacological properties. Compounds \u003cb\u003e4\u003c/b\u003e and \u003cb\u003e5\u003c/b\u003e, particularly promising, warrant further investigation into their mechanisms of action and in vivo efficacy, suggesting potential clinical applications in cancer therapy. Future studies should delve into structure-activity relationships to optimize (-)-curine analogs' cytotoxicity and selectivity.\u003c/p\u003e"},{"header":"Experimental section","content":"\u003cdiv id=\"Sec7\" class=\"Section2\"\u003e \u003ch2\u003eGeneral experimental procedures\u003c/h2\u003e \u003cp\u003eOptical rotations were measured on a JASCO-1020 polarimeter. IR spectra were obtained using a Frontier FT-IR Perkin-Elmer spectrophotometer. \u003csup\u003e1\u003c/sup\u003eH and \u003csup\u003e13\u003c/sup\u003eC NMR spectra were recorded on a Bruker AVANCE 400 FT-NMR spectrometer, operating at 400 MHz (\u003csup\u003e1\u003c/sup\u003eH) and 100 MHz (\u003csup\u003e13\u003c/sup\u003eC). ESTOFMS spectra were measured with a Bruker micrOTOF-II mass spectrometer. Unless otherwise indicated, column chromatography was carried out using Merck silica gel 60 (\u0026lt;\u0026thinsp;0.063 mm). For TLC, Merck precoated silica gel 60 F\u003csub\u003e254\u003c/sub\u003e plates were used. Spots on TLC were detected under UV light and by spraying with anisaldehyde-H\u003csub\u003e2\u003c/sub\u003eSO\u003csub\u003e4\u003c/sub\u003e reagent followed by heating.\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec8\" class=\"Section2\"\u003e \u003ch2\u003eExtraction and isolation of (\u0026minus;)-curine\u003c/h2\u003e \u003cp\u003e \u003cb\u003e(\u0026minus;)-\u003c/b\u003eCurine was isolated from the roots of \u003cem\u003eCissampelos pareira\u003c/em\u003e (Menispermaceae). Its structure was confirmed by spectroscopic methods and comparison with the reported literature [\u003cspan citationid=\"CR1\" class=\"CitationRef\"\u003e1\u003c/span\u003e].\u003c/p\u003e \u003cp\u003e \u003cb\u003e(\u0026minus;) -Curine (1)\u003c/b\u003e Pale yellow power; \u003cspan class=\"InlineEquation\"\u003e\u003cspan class=\"mathinline\"\u003e\\({\\text{[\u0026alpha;]}}_{\\text{D}}^{\\text{26}}\\)\u003c/span\u003e\u003c/span\u003e -167.9˚(\u003cem\u003ec\u003c/em\u003e 0.97, CHCl\u003csub\u003e3\u003c/sub\u003e); IR ν\u003csub\u003emax\u003c/sub\u003e: 3370, 2932, 2839, 2796, 1611, 1503, 1444, 1273, 1213, 1166, 1109, 1055, 907, 831, 801, 725 cm\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e; \u003csup\u003e1\u003c/sup\u003eH NMR (CDCl\u003csub\u003e3\u003c/sub\u003e, 400 MHz,): \u003cem\u003eδ\u003c/em\u003e 7.08 (1H, d, \u003cem\u003eJ\u003c/em\u003e\u0026thinsp;=\u0026thinsp;8.0 Hz, H-14\u0026prime;), 6.92 (1H, d, \u003cem\u003eJ\u003c/em\u003e\u0026thinsp;=\u0026thinsp;8.0 Hz, H-14), 6.79 (1H, d, \u003cem\u003eJ\u003c/em\u003e\u0026thinsp;=\u0026thinsp;8.0 Hz, H-13), 6.68 (1H, partially overlapping signal, H-13\u0026prime;), 6.66 (1H, s, H-5\u0026prime;), 6.63 (1H, d, \u003cem\u003eJ\u003c/em\u003e\u0026thinsp;=\u0026thinsp;8.0 Hz, H-11\u0026prime;), 6.60 (1H, br s, H-10), 6.53 (1H, s, H-5), 6.44 (1H, d, \u003cem\u003eJ\u003c/em\u003e\u0026thinsp;=\u0026thinsp;8.0 Hz, H-10\u0026prime;), 5.94 (1H, br s, H-8\u0026prime;), 3.88 (3H, s, 6\u0026prime;-OCH\u003csub\u003e3\u003c/sub\u003e), 3.55 (1H, d, \u003cem\u003eJ\u003c/em\u003e\u0026thinsp;=\u0026thinsp;7.6 Hz, H-1), 3.44 (1H, d, \u003cem\u003eJ\u003c/em\u003e\u0026thinsp;=\u0026thinsp;9.2 Hz, H-1\u0026prime;), 3.31 (1H, m, H-3), 3.22 (1H, m, H-3\u0026prime;), 3.13, 2.53 (2H, br d, \u003cem\u003eJ\u003c/em\u003e\u0026thinsp;=\u0026thinsp;11.8 Hz, H-α\u0026prime;), 2.97 (1H, overlapping signal, H-4), 2.92, 2.71 (2H, overlapping signal, H-4\u0026prime;), 2.87 (3H, s, 6-OCH\u003csub\u003e3\u003c/sub\u003e), 2.85 (1H, overlapping signal, H-3), 2.81, 2.74 (2H, overlapping signal, H-α), 2.79 (1H, overlapping signal, H-3\u0026prime;), 2.49 (3H, s, N\u0026prime;-CH\u003csub\u003e3\u003c/sub\u003e), 2.42 (1H, dd, \u003cem\u003eJ\u003c/em\u003e\u0026thinsp;=\u0026thinsp;16.8, 3.8 Hz, H-4), 2.27 (3H, s, N-CH\u003csub\u003e3\u003c/sub\u003e); \u003csup\u003e13\u003c/sup\u003eC NMR (CDCl\u003csub\u003e3\u003c/sub\u003e, 100 MHz,): \u003cem\u003eδ\u003c/em\u003e 155.4 (C-12\u0026prime;), 148.6 (C-6\u0026prime;), 146.5 (C-6), 146.3 (C-12), 144.2 (C-11), 143.2 (C-7\u0026prime;), 138.5 (C-8), 137.3 (C-7), 133.7 (C-9), 132.4 (C-9\u0026prime;), 132.2 (C-10\u0026prime;), 129.6 (C-4a\u0026prime;), 129.5 (C-14\u0026prime;), 126.6 (C-14), 125.1 (C-4a), 124.5 (C-8a), 124.5 (C-8a\u0026prime;), 120.7 (C-10), 120.2 (C-8\u0026prime;), 115.5 (C-11\u0026prime;), 115.2 (C-13), 113.3 (C-13\u0026prime;), 112.3 (C-5\u0026prime;), 108.1 (C-5), 65.4 (C-1\u0026prime;), 60.4 (C-1), 56.1 (6-O\u003cspan type=\"Underline\" class=\"Underline\" name=\"Emphasis\"\u003eC\u003c/span\u003eH\u003csub\u003e3\u003c/sub\u003e), 56.0 (6\u0026prime;-O\u003cspan type=\"Underline\" class=\"Underline\" name=\"Emphasis\"\u003eC\u003c/span\u003eH\u003csub\u003e3\u003c/sub\u003e), 45.7 (C-3\u0026prime;), 43.9 (C-3), 42.2 (N\u0026prime;-\u003cspan type=\"Underline\" class=\"Underline\" name=\"Emphasis\"\u003eC\u003c/span\u003eH\u003csub\u003e3\u003c/sub\u003e), 41.7 (N-\u003cspan type=\"Underline\" class=\"Underline\" name=\"Emphasis\"\u003eC\u003c/span\u003eH\u003csub\u003e3\u003c/sub\u003e), 39.9 (C-α), 39.7 (C- α\u0026prime;), 25.3 (C-4\u0026prime;), 21.9 (C-4); ESI MS \u003cem\u003em/z\u003c/em\u003e 595.9 [M\u0026thinsp;+\u0026thinsp;H]\u003csup\u003e+\u003c/sup\u003e.\u003c/p\u003e \u003c/div\u003e\n\u003ch3\u003eSynthesis of (−)-curine ester analogues\u003c/h3\u003e\n\u003cdiv id=\"Sec10\" class=\"Section2\"\u003e \u003ch2\u003ePreparation of Compounds 2 and 3\u003c/h2\u003e \u003cp\u003eA mixture of compound \u003cb\u003e1\u003c/b\u003e (50 mg, 0.08 mmol) was dissolved in CH\u003csub\u003e2\u003c/sub\u003eCl\u003csub\u003e2\u003c/sub\u003e (5 ml) and acetic anhydride (0.1 ml) was added. The reaction mixture was stirred at room temperature for 3 h. The mixture was poured into water (30 ml) and the solution was extracted with CH\u003csub\u003e2\u003c/sub\u003eCl\u003csub\u003e2\u003c/sub\u003e (100 ml). The organic phase was washed with water (3\u0026times;20 ml) and dried over anhydrous Na\u003csub\u003e2\u003c/sub\u003eSO\u003csub\u003e4\u003c/sub\u003e. The solvent was removed under reduced pressure and the product was purified by column chromatography using 4% MeOH in CH\u003csub\u003e2\u003c/sub\u003eCl\u003csub\u003e2\u003c/sub\u003e as eluent to yield compounds \u003cb\u003e2\u003c/b\u003e (22.0 mg, 37.5%) and \u003cb\u003e3\u003c/b\u003e (15.1 mg, 25%).\u003c/p\u003e \u003cp\u003e \u003cb\u003e7,12-Diacetoxylcurine (2)\u003c/b\u003e Pale-yellow powder; \u003cspan class=\"InlineEquation\"\u003e\u003cspan class=\"mathinline\"\u003e\\({\\text{[\u0026alpha;]}}_{\\text{D}}^{\\text{27}}\\)\u003c/span\u003e\u003c/span\u003e -114.34 (c\u0026thinsp;=\u0026thinsp;0.32, CH\u003csub\u003e2\u003c/sub\u003eCl\u003csub\u003e2\u003c/sub\u003e); IR ν\u003csub\u003emax\u003c/sub\u003e : 2931, 2845, 1764, 1609, 1503, 1418, 1367, 1271, 1214, 1186, 1112, 1055, 1011, 905, 834, 726 cm\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e; \u003csup\u003e1\u003c/sup\u003eH NMR (CDCl\u003csub\u003e3\u003c/sub\u003e, 400 MHz,): \u003cem\u003eδ\u003c/em\u003e 7.10 (1H, d, \u003cem\u003eJ\u003c/em\u003e\u0026thinsp;=\u0026thinsp;8.0 Hz, H-14), 7.09 (1H, d, \u003cem\u003eJ\u003c/em\u003e\u0026thinsp;=\u0026thinsp;8.0 Hz, H-14\u0026prime;), 6.91 (1H, d, \u003cem\u003eJ\u003c/em\u003e\u0026thinsp;=\u0026thinsp;8.0 Hz, H-13), 6.69 (1H, d, \u003cem\u003eJ\u003c/em\u003e\u0026thinsp;=\u0026thinsp;8.0 Hz, H-13\u0026prime;), 6.63 (1H, br s, H-5\u0026prime;), 6.62 (1H, d, \u003cem\u003eJ\u003c/em\u003e\u0026thinsp;=\u0026thinsp;8.0 Hz, H-11\u0026prime;), 6.58 (1H, s, H-5), 6.58 (1H, br s, H-10), 6.40 (1H, d, \u003cem\u003eJ\u003c/em\u003e\u0026thinsp;=\u0026thinsp;8.0 Hz, H-10\u0026prime;), 5.48 (1H, s, H-8\u0026prime;), 3.79 (3H, s, 6-OCH\u003csub\u003e3\u003c/sub\u003e), 3.78 (3H, s, 6\u0026prime;-OCH\u003csub\u003e3\u003c/sub\u003e), 3.55 (1H, d, \u003cem\u003eJ\u003c/em\u003e\u0026thinsp;=\u0026thinsp;10.8 Hz, H-1\u0026prime;), 3.48 (1H, d, \u003cem\u003eJ\u003c/em\u003e\u0026thinsp;=\u0026thinsp;8.4 Hz, H-1), 3.30 (2H, m, H-3,3\u0026prime;), 3.26, (2H, br d, \u003cem\u003eJ\u003c/em\u003e\u0026thinsp;=\u0026thinsp;11.6 Hz, H- α, α\u0026prime;), 2.98 (2H, overlapping signal, H-4, 4\u0026prime;), 2.87 (1H, overlapping signal, H-3), 2.82 (1H, overlapping signal, H-3\u0026prime;), 2.66 (2H, d, \u003cem\u003eJ\u003c/em\u003e\u0026thinsp;=\u0026thinsp;14.4 Hz, H-α), 2.53 (3H, s, N\u0026prime;-CH\u003csub\u003e3\u003c/sub\u003e), 2.45 (1H, dd, \u003cem\u003eJ\u003c/em\u003e\u0026thinsp;=\u0026thinsp;18.0, 4.0 Hz, H-4), 2.24 (3H, s, N-CH\u003csub\u003e3\u003c/sub\u003e), 2.06 (3H, s, H-2\u0026prime;\u0026prime;), 2.01 (3H, s, H-2\u0026prime;\u0026prime;\u0026prime;); \u003csup\u003e13\u003c/sup\u003eC NMR (CDCl\u003csub\u003e3\u003c/sub\u003e, 100 MHz,): \u003cem\u003eδ\u003c/em\u003e 168.8 (C-1\u0026prime;\u0026prime;\u0026prime;), 168.4 (C-1\u0026prime;\u0026prime;), 155.2 (C-12\u0026prime;),150.8 (C-6), 148.8 (C-6\u0026prime;), 146.7 (C-11), 144.5 (C-8), 143.8 (C-7\u0026prime;), 140.6 (C-12), 140.3 (C-9), 132.9 (C-10\u0026prime;), 132.2 (C-7), 131.3 (C-9\u0026prime;), 129.8 (C-14\u0026prime;), 126.9 (C-4a\u0026prime;), 126.5 (C-8a\u0026prime;), 125.8 (C-14), 124.1 (C-4a, C-8a), 122.7 (C-13), 122.2 (C-10), 117.7 (C-8\u0026prime;), 115.2 (C-11\u0026prime;), 114.1 (C-13\u0026prime;), 112.3 (C-5\u0026prime;), 108.9 (C-5), 64.9 (C-1\u0026prime;), 60.6 (C-1), 56.0 (6-O\u003cspan type=\"Underline\" class=\"Underline\" name=\"Emphasis\"\u003eC\u003c/span\u003eH\u003csub\u003e3\u003c/sub\u003e), 55.9 (6\u0026prime;-O\u003cspan type=\"Underline\" class=\"Underline\" name=\"Emphasis\"\u003eC\u003c/span\u003eH\u003csub\u003e3\u003c/sub\u003e), 44.8 (C-3\u0026prime;), 43.3 (C-3), 41.5 (N-\u003cspan type=\"Underline\" class=\"Underline\" name=\"Emphasis\"\u003eC\u003c/span\u003eH\u003csub\u003e3\u003c/sub\u003e), 41.1 (N\u0026prime;-\u003cspan type=\"Underline\" class=\"Underline\" name=\"Emphasis\"\u003eC\u003c/span\u003eH\u003csub\u003e3\u003c/sub\u003e), 40.2 (C-α), 39.5 (C- α\u0026prime;), 24.0 (C-4\u0026prime;), 21.9 (C-4), 20.4 (C-2\u0026prime;\u0026prime;\u0026prime;), 20.1 (C-2\u0026prime;\u0026prime;); HR-TOF-MS (ESI\u003csup\u003e+\u003c/sup\u003e): \u003cem\u003em/z\u003c/em\u003e 679.3029 [M\u0026thinsp;+\u0026thinsp;H]\u003csup\u003e+\u003c/sup\u003e (calcd. for C\u003csub\u003e40\u003c/sub\u003eH\u003csub\u003e43\u003c/sub\u003eN\u003csub\u003e2\u003c/sub\u003eO\u003csub\u003e8\u003c/sub\u003e, 679.3014). The physical and spectral data were in agreement with those reported in the literature [\u003cspan citationid=\"CR9\" class=\"CitationRef\"\u003e9\u003c/span\u003e].\u003c/p\u003e \u003cp\u003e \u003cb\u003e7-Acetoxylcurine (3)\u003c/b\u003e Pale-yellow powder; \u003cspan class=\"InlineEquation\"\u003e\u003cspan class=\"mathinline\"\u003e\\({\\text{[\u0026alpha;]}}_{\\text{D}}^{\\text{27}}\\)\u003c/span\u003e\u003c/span\u003e -132.57 (c\u0026thinsp;=\u0026thinsp;0.35, CH\u003csub\u003e2\u003c/sub\u003eCl\u003csub\u003e2\u003c/sub\u003e); IR ν\u003csub\u003emax\u003c/sub\u003e: 3380, 2928, 2845, 1765, 1609, 1579, 1504, 1438, 1368, 1271, 1188, 1112, 1056, 1013, 902, 833, 726 cm\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e; \u003csup\u003e1\u003c/sup\u003eH NMR (CDCl\u003csub\u003e3\u003c/sub\u003e, 400 MHz,): \u003cem\u003eδ\u003c/em\u003e 7.12 (1H, d, \u003cem\u003eJ\u003c/em\u003e\u0026thinsp;=\u0026thinsp;7.6 Hz, H-14\u0026prime;), 6.91 (1H, d, \u003cem\u003eJ\u003c/em\u003e\u0026thinsp;=\u0026thinsp;7.6 Hz, H-14), 6.79 (1H, d, \u003cem\u003eJ\u003c/em\u003e\u0026thinsp;=\u0026thinsp;7.6 Hz, H-13), 6.68 (1H, overlapping signal, H-5\u0026prime;), 6.68 (1H, overlapping signal, H-13\u0026prime;), 6.61 (1H, s, H-5), 6.65 (1H, br s, H-10), 6.64 (1H, overlapping signal, H-11\u0026prime;), 6.54 (1H, d, \u003cem\u003eJ\u003c/em\u003e\u0026thinsp;=\u0026thinsp;7.6 Hz, H-10\u0026prime;), 5.92 (1H, s, H-8\u0026prime;), 3.89 (3H, s, 6\u0026prime;-OCH\u003csub\u003e3\u003c/sub\u003e), 3.83 (3H, s, 6-OCH\u003csub\u003e3\u003c/sub\u003e), 3.52 (1H, d, \u003cem\u003eJ\u003c/em\u003e\u0026thinsp;=\u0026thinsp;8.0 Hz, H-1), 3.48 (1H, d, \u003cem\u003eJ\u003c/em\u003e\u0026thinsp;=\u0026thinsp;15.2 Hz, H-1\u0026prime;), 3.36 (1H, m, H-3), 3.29 (1H, m, H-3\u0026prime;), 3.24 (1H, overlapping signal, H-α\u0026prime;), 2.98 (1H, m, H-4), 2.94 (1H, m, H-4\u0026prime;), 2.90 (1H, overlapping signal, H-3), 2.81 (1H, overlapping signal, H-4\u0026prime;), 2.77 (2H, overlapping signal, H-α, α\u0026prime;), 2.55 (1H, overlapping signal, H-α), 2.53 (3H, s, N\u0026prime;-CH\u003csub\u003e3\u003c/sub\u003e), 2.48 (1H, dd, \u003cem\u003eJ\u003c/em\u003e\u0026thinsp;=\u0026thinsp;17.4, 4.2 Hz, H-4), 2.25 (3H, s, N-CH\u003csub\u003e3\u003c/sub\u003e), 2.11 (3H, s, H-2\u0026prime;\u0026prime;); \u003csup\u003e13\u003c/sup\u003eC NMR (CDCl\u003csub\u003e3\u003c/sub\u003e, 100 MHz,): \u003cem\u003eδ\u003c/em\u003e 168.6 (C-1\u0026prime;\u0026prime;), 155.3 (C-12\u0026prime;), 150.7 (C-6), 148.7 (C-6\u0026prime;), 146.4 (C-12), 144.6 (C-8), 144.0 (C-11), 143.4 (C-7\u0026prime;), 133.6 (C-9), 132.9 (C-7), 132.2 (C-10\u0026prime;), 131.7 (4a\u0026prime;, C-9\u0026prime;), 129.6 (C-14\u0026prime;), 127.1 (C-8a\u0026prime;), 126.8 (C-14), 124.3 (C-4a), 123.6 (C-8a), 120.9 (C-10), 119.8 (C-8\u0026prime;), 115.7 (C-11\u0026prime;), 115.3 (C-13), 113.8 (C-13\u0026prime;), 112.3 (C-5\u0026prime;), 108.9 (C-5), 65.5 (C-1\u0026prime;), 60.4 (C-1), 56.1 (6-O\u003cspan type=\"Underline\" class=\"Underline\" name=\"Emphasis\"\u003eC\u003c/span\u003eH\u003csub\u003e3,\u003c/sub\u003e 6\u0026prime;-O\u003cspan type=\"Underline\" class=\"Underline\" name=\"Emphasis\"\u003eC\u003c/span\u003eH\u003csub\u003e3\u003c/sub\u003e), 45.7 (C-3\u0026prime;), 43.6 (C-3), 42.0 (N-\u003cspan type=\"Underline\" class=\"Underline\" name=\"Emphasis\"\u003eC\u003c/span\u003eH\u003csub\u003e3\u003c/sub\u003e), 41.7 (N\u0026prime;-\u003cspan type=\"Underline\" class=\"Underline\" name=\"Emphasis\"\u003eC\u003c/span\u003eH\u003csub\u003e3\u003c/sub\u003e), 39.8 (C-α, α\u0026prime;), 25.3 (C-4\u0026prime;), 22.2 (C-4), 20.2 (C-2\u0026prime;\u0026prime;); HR-TOF-MS (ESI\u003csup\u003e+\u003c/sup\u003e): \u003cem\u003em/z\u003c/em\u003e 637.2918 [M\u0026thinsp;+\u0026thinsp;H]\u003csup\u003e+\u003c/sup\u003e (calcd. for C\u003csub\u003e38\u003c/sub\u003eH\u003csub\u003e41\u003c/sub\u003eN\u003csub\u003e2\u003c/sub\u003eO\u003csub\u003e7\u003c/sub\u003e, 637.2908).\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec11\" class=\"Section2\"\u003e \u003ch2\u003ePreparation of Compound 4\u003c/h2\u003e \u003cp\u003eA mixture of compound \u003cb\u003e1\u003c/b\u003e (100 mg, 0.17 mmol) was dissolved in CH\u003csub\u003e2\u003c/sub\u003eCl\u003csub\u003e2\u003c/sub\u003e (10 ml) and N,N\u0026prime;-diisopropylcarbodiimide (DIC) (0.1 ml), 4-N,N\u0026prime;-dimethylaminopyridine (DMAP) (1 mg, 0.01 mmol) and 1,6-dihydrocyclopenta[c]pyrazole-3-carboxylic acid (10 mg, 0.07 mmol) was added. The reaction mixture was stirred at room temperature for 72 h. The mixture was poured into water (30 ml) and the solution was extracted with CH\u003csub\u003e2\u003c/sub\u003eCl\u003csub\u003e2\u003c/sub\u003e (100 ml). The organic phase was washed with water (3\u0026times;20 ml) and dried over anhydrous Na\u003csub\u003e2\u003c/sub\u003eSO\u003csub\u003e4\u003c/sub\u003e. The solvent was removed under reduced pressure and the product was purified by column chromatography using 4% MeOH in CH\u003csub\u003e2\u003c/sub\u003eCl\u003csub\u003e2\u003c/sub\u003e to yield compound \u003cb\u003e4\u003c/b\u003e (41.5 mg, 35.3%).\u003c/p\u003e \u003cp\u003e \u003cb\u003e7-(1,6-dihydrocyclopenta[c]pyrazole-3-carboxyl)-curine (4)\u003c/b\u003e Pale-yellow powder; \u003cspan class=\"InlineEquation\"\u003e\u003cspan class=\"mathinline\"\u003e\\({\\text{[\u0026alpha;]}}_{\\text{D}}^{\\text{27}}\\)\u003c/span\u003e\u003c/span\u003e -196.10 (c\u0026thinsp;=\u0026thinsp;0.30, CH\u003csub\u003e2\u003c/sub\u003eCl\u003csub\u003e2\u003c/sub\u003e); IR ν\u003csub\u003emax\u003c/sub\u003e: 3312, 2932, 2849, 1740, 1609, 1504, 1441, 1272, 1209, 1108, 1023, 834, 765 cm\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e; \u003csup\u003e1\u003c/sup\u003eH NMR (CDCl\u003csub\u003e3\u003c/sub\u003e, 400 MHz,): \u003cem\u003eδ\u003c/em\u003e 7.07 (1H, d, \u003cem\u003eJ\u003c/em\u003e\u0026thinsp;=\u0026thinsp;8.0 Hz, H-14\u0026prime;), 6.92 (1H, d, \u003cem\u003eJ\u003c/em\u003e\u0026thinsp;=\u0026thinsp;8.0 Hz, H-14), 6.78 (1H, d, \u003cem\u003eJ\u003c/em\u003e\u0026thinsp;=\u0026thinsp;8.0 Hz, H-13), 6.69 (1H, overlapping signal, H-13\u0026prime;), 6.65 (1H, br s, H-5\u0026prime;), 6.63 (1H, overlapping signal, H-5, 5\u0026prime;\u0026prime;), 6.57 (1H, d, \u003cem\u003eJ\u003c/em\u003e\u0026thinsp;=\u0026thinsp;8.0 Hz, H-11\u0026prime;), 6.55 (2H, overlapping signal, H-10,4\u0026prime;\u0026prime;), 6.42 (1H, d, \u003cem\u003eJ\u003c/em\u003e\u0026thinsp;=\u0026thinsp;7.6 Hz, H-10\u0026prime;), 5.91 (1H, s, H-8\u0026prime;), 3.86 (3H, s, 6\u0026prime;-OCH\u003csub\u003e3\u003c/sub\u003e), 3.80 (3H, s, 6-OCH\u003csub\u003e3\u003c/sub\u003e), 3.56 (1H, d, \u003cem\u003eJ\u003c/em\u003e\u0026thinsp;=\u0026thinsp;7.6 Hz, H-1), 3.47 (1H, d, \u003cem\u003eJ\u003c/em\u003e\u0026thinsp;=\u0026thinsp;5.6 Hz, H-1\u0026prime;), 3.35 (1H, m, H-3), 3.25 (1H, m, H-3\u0026prime;), 3.17, 2.55 (2H, br d, \u003cem\u003eJ\u003c/em\u003e\u0026thinsp;=\u0026thinsp;11.6 Hz, H-α\u0026prime;), 3.01 (1H, m, H-4), 2.97 (1H, overlapping signal, H-4\u0026prime;), 2.90 (1H, overlapping signal, H-3), 2.81 (1H, overlapping signal, H-3\u0026prime;), 2.78 (1H, overlapping signal, H-α), 2.74 (1H, d, \u003cem\u003eJ\u003c/em\u003e\u0026thinsp;=\u0026thinsp;12.4 Hz, H-α), 2.67 (1H, m, H-4\u0026prime;), 2.49 (1H, overlapping signal, H-4), 2.48 (3H, s, N\u0026prime;-CH\u003csub\u003e3\u003c/sub\u003e), 2.34 (2H, m, H-6\u0026prime;\u0026prime;), 2.27 (3H, s, N-CH\u003csub\u003e3\u003c/sub\u003e); \u003csup\u003e13\u003c/sup\u003eC NMR (CDCl\u003csub\u003e3\u003c/sub\u003e, 100 MHz,): \u003cem\u003eδ\u003c/em\u003e 157.5 (C-7\u0026prime;\u0026prime;), 155.4 (C-12\u0026prime;), 150.8 (C-6), 148.7 (C-6\u0026prime;), 146.3 (C-12), 144.7 (C-8), 144.0 (C-11), 143.2 (C-7\u0026prime;), 133.5 (C-7), 133.3 (C-9), 132.4 (C-9\u0026prime;), 132.0 (C-10\u0026prime;), 130.9 (C-3a\u0026prime;\u0026prime;), 130.6 (C-4a\u0026prime;), 129.6 (C-14\u0026prime;), 129.3 (C-8a\u0026prime;), 129.1(C-6a\u0026prime;\u0026prime;), 126.5 (C-14), 124.6 (C-4a, 8a,), 120.7 (C-10), 120.0 (C-8\u0026prime;), 115.4 (C-11\u0026prime;), 115.3 (C-13, 5\u0026prime;\u0026prime;), 113.9 (C-13\u0026prime;), 112.3 (C-5\u0026prime;), 109.0 (C-5), 108.1 (C-4\u0026prime;\u0026prime;), 65.3 (C-1\u0026prime;), 60.3 (C-1), 56.1 (6-O\u003cspan type=\"Underline\" class=\"Underline\" name=\"Emphasis\"\u003eC\u003c/span\u003eH\u003csub\u003e3\u003c/sub\u003e), 55.9 (6\u0026prime;-O\u003cspan type=\"Underline\" class=\"Underline\" name=\"Emphasis\"\u003eC\u003c/span\u003eH\u003csub\u003e3\u003c/sub\u003e), 45.6 (C-3\u0026prime;), 43.6 (C-3), 42.0 (N-\u003cspan type=\"Underline\" class=\"Underline\" name=\"Emphasis\"\u003eC\u003c/span\u003eH\u003csub\u003e3\u003c/sub\u003e), 41.8 (N\u0026prime;-\u003cspan type=\"Underline\" class=\"Underline\" name=\"Emphasis\"\u003eC\u003c/span\u003eH\u003csub\u003e3\u003c/sub\u003e), 39.7 (C-α, α\u0026prime;), 29.9 (C-6\u0026prime;\u0026prime;), 25.1 (C-4\u0026prime;), 24.4 (C-4); HR-TOF-MS (ESI\u003csup\u003e+\u003c/sup\u003e): \u003cem\u003em/z\u003c/em\u003e 727.3105 [M\u0026thinsp;+\u0026thinsp;H]\u003csup\u003e+\u003c/sup\u003e (calcd. for C\u003csub\u003e45\u003c/sub\u003eH\u003csub\u003e43\u003c/sub\u003eN\u003csub\u003e4\u003c/sub\u003eO\u003csub\u003e7\u003c/sub\u003e, 727.3126).\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec12\" class=\"Section2\"\u003e \u003ch2\u003ePreparation of Compound 5\u003c/h2\u003e \u003cp\u003eA mixture of compound \u003cb\u003e1\u003c/b\u003e (100 mg, 0.17 mmol) was dissolved in CH\u003csub\u003e2\u003c/sub\u003eCl\u003csub\u003e2\u003c/sub\u003e (10 ml). To this solution, N,N'-diisopropylcarbodiimide (DIC) (0.1 ml), 4-N,N'-dimethylaminopyridine (DMAP) (1 mg, 0.01 mmol), and thiophene-2-carbonyl chloride (10 mg, 0.08 mmol) were added and stirred at room temperature for 24 h. The mixture was poured into water (30 ml) and the solution was extracted with CH\u003csub\u003e2\u003c/sub\u003eCl\u003csub\u003e2\u003c/sub\u003e (100 ml). The organic phase was washed with water (3\u0026times;20 ml) and dried over anhydrous Na\u003csub\u003e2\u003c/sub\u003eSO\u003csub\u003e4\u003c/sub\u003e. The solvent was removed under reduced pressure and the product was purified by column chromatography using 6% MeOH in CH\u003csub\u003e2\u003c/sub\u003eCl\u003csub\u003e2\u003c/sub\u003e to yield compound \u003cb\u003e5\u003c/b\u003e (108.9 mg, 94.1%).\u003c/p\u003e \u003cp\u003e \u003cb\u003e7,12-Dithiophene-2-carbonylcurine (5)\u003c/b\u003e Pale yellow powder; \u003cspan class=\"InlineEquation\"\u003e\u003cspan class=\"mathinline\"\u003e\\({\\text{[\u0026alpha;]}}_{\\text{D}}^{\\text{27}}\\)\u003c/span\u003e\u003c/span\u003e -211.59 (c\u0026thinsp;=\u0026thinsp;0.32, CH\u003csub\u003e2\u003c/sub\u003eCl\u003csub\u003e2\u003c/sub\u003e); IR ν\u003csub\u003emax\u003c/sub\u003e: 3341, 2929, 2841, 1729, 1609, 1502, 1414, 1359, 1250, 1201, 1112, 1050, 1014, 834, 734 cm\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e; \u003csup\u003e1\u003c/sup\u003eH NMR (CDCl\u003csub\u003e3\u003c/sub\u003e, 400 MHz,): \u003cem\u003eδ\u003c/em\u003e 7.74 (1H, br s, H-3\u0026prime;\u0026prime;\u0026prime;), 7.72 (1H, br s, H-3\u0026prime;\u0026prime;), 7.52 (2H, br s, H-5\u0026prime;\u0026prime;, H-5\u0026prime;\u0026prime;\u0026prime;), 7.19 (1H, d, \u003cem\u003eJ\u003c/em\u003e\u0026thinsp;=\u0026thinsp;7.6 Hz, H-14), 7.06 (1H, d, \u003cem\u003eJ\u003c/em\u003e\u0026thinsp;=\u0026thinsp;7.6 Hz, H-13), 7.05 (1H, overlapping signal, H-4\u0026prime;\u0026prime;\u0026prime;), 7.01 (2H, overlapping signal, H-14\u0026prime;,4\u0026prime;\u0026prime;), 6.74 (1H, br s, H-11\u0026prime;), 6.65 (2H, overlapping signal, H-13\u0026prime;, H-5), 6.70 (1H, br s, H-10), 6.44 (1H, br s, H-5\u0026prime;), 6.44 (1H, overlapping signal, H-10\u0026prime;), 5.49 (1H, s, H-8\u0026prime;), 3.82 (3H, s, 6-OCH\u003csub\u003e3\u003c/sub\u003e), 3.53 (1H, d, \u003cem\u003eJ\u003c/em\u003e\u0026thinsp;=\u0026thinsp;8.0 Hz, H-1), 3.42, 2.94 (2H, overlapping signal, H-3), 3.42 (3H, s, 6\u0026prime;-OCH\u003csub\u003e3\u003c/sub\u003e), 3.36 (1H, d, \u003cem\u003eJ\u003c/em\u003e\u0026thinsp;=\u0026thinsp;8.0 Hz, H-1\u0026prime;), 3.11 (1H, br d, \u003cem\u003eJ\u003c/em\u003e\u0026thinsp;=\u0026thinsp;12.0 Hz, H-α\u0026prime;), 3.19 (1H, m, H-3\u0026prime;), 3.05, 2.49 (2H, overlapping signal, H-4), 2.91 (1H, overlapping signal, H-4\u0026prime;), 2.86, 2.76 (2H, overlapping signal, H-α), 2.76 (1H, overlapping signal, H-3\u0026prime;), 2.63 (1H, m, H-4\u0026prime;), 2.49 (1H, overlapping signal, H-α\u0026prime;), 2.49 (3H, s, N\u0026prime;-CH\u003csub\u003e3\u003c/sub\u003e), 2.29 (3H, s, N-CH\u003csub\u003e3\u003c/sub\u003e); \u003csup\u003e13\u003c/sup\u003eC NMR (CDCl\u003csub\u003e3\u003c/sub\u003e, 100 MHz,): \u003cem\u003eδ\u003c/em\u003e 159.8 (C-6\u0026prime;\u0026prime;\u0026prime;), 159.5 (C-6\u0026prime;\u0026prime;), 155.0 (C-12\u0026prime;), 151.1 (C-6), 148.2 (C-6\u0026prime;), 147.0 (C-12), 144.9 (C-8), 143.4 (C-11), 140.9 (C-7\u0026prime;), 134.7 (C-3\u0026prime;\u0026prime;), 134.1 (C-3\u0026prime;\u0026prime;\u0026prime;), 133.2 (C-2\u0026prime;\u0026prime;, 5\u0026prime;\u0026prime;, 2\u0026prime;\u0026prime;\u0026prime;), 133.2 (C-9\u0026prime;), 132.8 (C-5\u0026prime;\u0026prime;\u0026prime;), 132.4 (C-9), 132.3 (C-10\u0026prime;), 131.2 (C-7), 129.5 (C-14\u0026prime;), 127.8 (C-4a\u0026prime;, 8a\u0026prime;), 127.6 (C-4\u0026prime;\u0026prime;), 127.5 (C-4\u0026prime;\u0026prime;\u0026prime;), 125.6 (C-14), 124.4 (C-4a, 8a), 122.7 (C-10, 13), 117.8 (C-8\u0026prime;), 115.2 (C-11\u0026prime;), 113.4 (C-13\u0026prime;), 111.8 (C-5\u0026prime;), 109.0 (C-5), 65.3 (C-1\u0026prime;), 60.8 (C-1), 56.1 (6-O\u003cspan type=\"Underline\" class=\"Underline\" name=\"Emphasis\"\u003eC\u003c/span\u003eH\u003csub\u003e3\u003c/sub\u003e), 55.1 (6\u0026prime;-O\u003cspan type=\"Underline\" class=\"Underline\" name=\"Emphasis\"\u003eC\u003c/span\u003eH\u003csub\u003e3\u003c/sub\u003e), 45.9 (C-3\u0026prime;), 43.4 (C-3), 42.4 (N\u0026prime;-\u003cspan type=\"Underline\" class=\"Underline\" name=\"Emphasis\"\u003eC\u003c/span\u003eH\u003csub\u003e3\u003c/sub\u003e), 41.6 (N-\u003cspan type=\"Underline\" class=\"Underline\" name=\"Emphasis\"\u003eC\u003c/span\u003eH\u003csub\u003e3\u003c/sub\u003e), 40.3 (C- α\u0026prime;), 39.3 (C-α), 25.5 (C-4\u0026prime;), 22.0 (C-4); HR-TOF-MS (ESI\u003csup\u003e+\u003c/sup\u003e): \u003cem\u003em/z\u003c/em\u003e 815.2452 [M\u0026thinsp;+\u0026thinsp;H]\u003csup\u003e+\u003c/sup\u003e (calcd. for C\u003csub\u003e46\u003c/sub\u003eH\u003csub\u003e43\u003c/sub\u003eN\u003csub\u003e2\u003c/sub\u003eO\u003csub\u003e8\u003c/sub\u003eS\u003csub\u003e2\u003c/sub\u003e, 815.2452).\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec13\" class=\"Section2\"\u003e \u003ch2\u003ePreparation of Compound 6\u003c/h2\u003e \u003cp\u003eA mixture of compound \u003cb\u003e1\u003c/b\u003e (100 mg, 0.17 mmol) was dissolved in CH\u003csub\u003e2\u003c/sub\u003eCl\u003csub\u003e2\u003c/sub\u003e (10 ml) and N,N׳-diisopropylcarbodiimide (DIC) (0.1 ml), 4-N,N׳-dimethylaminopyridine (DMAP) (1 mg, 0.01 mmol) and 4-Chlorocinamic acid (10 mg, 0.05 mmol) was stirred at room temperature for 96 h. The mixture was poured into water (30 ml) and the solution was extracted with CH\u003csub\u003e2\u003c/sub\u003eCl\u003csub\u003e2\u003c/sub\u003e (100 ml). The organic phase was washed with water (3\u0026times;20 ml) and dried over anhydrous Na\u003csub\u003e2\u003c/sub\u003eSO\u003csub\u003e4\u003c/sub\u003e. The solvent was removed under reduced pressure, and the product was purified by column chromatography using 4% MeOH in CH\u003csub\u003e2\u003c/sub\u003eCl\u003csub\u003e2\u003c/sub\u003e, yielding compound \u003cb\u003e6\u003c/b\u003e (47.1 mg, 35.2%).\u003c/p\u003e \u003cp\u003e \u003cb\u003e7-(4-Chlorocinamoyl)-curine (6)\u003c/b\u003e Pale yellow powder; \u003cspan class=\"InlineEquation\"\u003e\u003cspan class=\"mathinline\"\u003e\\({\\text{[\u0026alpha;]}}_{\\text{D}}^{\\text{27}}\\)\u003c/span\u003e\u003c/span\u003e -208.18 (\u003cem\u003ec\u003c/em\u003e\u0026thinsp;=\u0026thinsp;0.32, CH\u003csub\u003e2\u003c/sub\u003eCl\u003csub\u003e2\u003c/sub\u003e); IR ν\u003csub\u003emax\u003c/sub\u003e: 2930, 2840, 1734, 1635, 1609, 1504, 1444, 1272, 1207, 1111, 1089, 820, 727 cm\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e; \u003csup\u003e1\u003c/sup\u003eH NMR (CDCl\u003csub\u003e3\u003c/sub\u003e, 400 MHz,): \u003cem\u003eδ\u003c/em\u003e 7.57 (1H, br d, \u003cem\u003eJ\u003c/em\u003e\u0026thinsp;=\u0026thinsp;15.8 Hz, H-7\u0026prime;\u0026prime;), 7.37 (1H, d, \u003cem\u003eJ\u003c/em\u003e\u0026thinsp;=\u0026thinsp;7.6 Hz, H-2\u0026prime;\u0026prime;,6\u0026prime;\u0026prime;), 7.31 (1H, d, \u003cem\u003eJ\u003c/em\u003e\u0026thinsp;=\u0026thinsp;7.6 Hz, H-3\u0026prime;\u0026prime;,5\u0026prime;\u0026prime;), 7.06 (1H, d, \u003cem\u003eJ\u003c/em\u003e\u0026thinsp;=\u0026thinsp;7.6 Hz, H-14\u0026prime;), 6.92 (1H, d, \u003cem\u003eJ\u003c/em\u003e\u0026thinsp;=\u0026thinsp;7.6 Hz, H-14), 6.79 (1H, d, \u003cem\u003eJ\u003c/em\u003e\u0026thinsp;=\u0026thinsp;7.6 Hz, H-13), 6.72 (1H, d, \u003cem\u003eJ\u003c/em\u003e\u0026thinsp;=\u0026thinsp;7.6 Hz, H-13\u0026prime;), 6.67 (1H, br s, H-5\u0026prime;), 6.64 (2H, overlapping signal, H-5, H-10), 6.61 (1H, overlapping signal, H-11\u0026prime;), 6.46 (1H, br d, \u003cem\u003eJ\u003c/em\u003e\u0026thinsp;=\u0026thinsp;15.8 Hz, H-8\u0026prime;\u0026prime;), 6.45 (1H, overlapping signal, H-10\u0026prime;), 5.94 (1H, s, H-8\u0026prime;), 3.88 (3H, s, 6\u0026prime;-OCH\u003csub\u003e3\u003c/sub\u003e), 3.84 (3H, s, 6-OCH\u003csub\u003e3\u003c/sub\u003e), 3.54 (1H, d, \u003cem\u003eJ\u003c/em\u003e\u0026thinsp;=\u0026thinsp;7.6 Hz, H-1), 3.43 (1H, d, \u003cem\u003eJ\u003c/em\u003e\u0026thinsp;=\u0026thinsp;10.4 Hz, H-1\u0026prime;), 3.35 (1H, m, H-3), 3.21 (1H, m, H-3\u0026prime;), 3.16 (1H, br d, \u003cem\u003eJ\u003c/em\u003e\u0026thinsp;=\u0026thinsp;13.2 Hz, H-α\u0026prime;), 3.02 (1H, m, H-4), 2.90, 2.75 (2H, overlapping signal, H-4\u0026prime;), 2.88 (1H, overlapping signal, H-3), 2.79 (3H, overlapping signal, H-α, 3\u0026prime;), 2.57 (1H, overlapping signal, H-α\u0026prime;), 2.51 (1H, overlapping signal, H-4), 2.51 (3H, s, N\u0026prime;-CH\u003csub\u003e3\u003c/sub\u003e), 2.27 (3H, s, N-CH\u003csub\u003e3\u003c/sub\u003e); \u003csup\u003e13\u003c/sup\u003eC NMR (CDCl\u003csub\u003e3\u003c/sub\u003e, 100 MHz,): \u003cem\u003eδ\u003c/em\u003e 164.2 (C-9\u0026prime;\u0026prime;), 155.4 (C-12\u0026prime;), 150.8 (C-6), 148.6 (C-6\u0026prime;), 146.4 (C-12), 145.1 (C-7\u0026prime;\u0026prime;), 144.7 (C-8), 144.1 (C-11), 143.3 (C-7\u0026prime;), 136.4 (C-4\u0026prime;\u0026prime;), 133.6 (C-9), 133.1 (C-1\u0026prime;\u0026prime;), 132.6 (C-9\u0026prime;), 132.5 (C-10\u0026prime;), 131.6 (C-7), 129.6 (C-14\u0026prime;), 129.4 (C-2\u0026prime;\u0026prime;, C-6\u0026prime;\u0026prime;), 129.2 (C-3\u0026prime;\u0026prime;, C-5\u0026prime;\u0026prime;), 129.1 (C-4a\u0026prime;, C-8a\u0026prime;), 126.7 (C-14), 124.4 (C-4a, C-8a), 120.9 (C-10), 119.9 (C-8\u0026prime;), 117.0 (C-8\u0026prime;\u0026prime;), 115.7 (C-11\u0026prime;), 115.3 (C-13), 113.9 (C-13\u0026prime;), 112.3 (C-5\u0026prime;), 108.9 (C-5), 65.5 (C-1\u0026prime;), 60.3 (C-1), 56.1 (6-O\u003cspan type=\"Underline\" class=\"Underline\" name=\"Emphasis\"\u003eC\u003c/span\u003eH\u003csub\u003e3\u003c/sub\u003e), 56.0 (6\u0026prime;-O\u003cspan type=\"Underline\" class=\"Underline\" name=\"Emphasis\"\u003eC\u003c/span\u003eH\u003csub\u003e3\u003c/sub\u003e), 45.9 (C-3\u0026prime;), 43.6 (C-3), 42.3 (N\u0026prime;-\u003cspan type=\"Underline\" class=\"Underline\" name=\"Emphasis\"\u003eC\u003c/span\u003eH\u003csub\u003e3\u003c/sub\u003e), 41.7 (N-\u003cspan type=\"Underline\" class=\"Underline\" name=\"Emphasis\"\u003eC\u003c/span\u003eH\u003csub\u003e3\u003c/sub\u003e), 39.7 (C-α, α\u0026prime;), 25.5 (C-4\u0026prime;), 22.2 (C-4); HR-TOF-MS (ESI\u003csup\u003e+\u003c/sup\u003e): \u003cem\u003em/z\u003c/em\u003e 759.2820 [M\u0026thinsp;+\u0026thinsp;H]\u003csup\u003e+\u003c/sup\u003e (calcd. for C\u003csub\u003e45\u003c/sub\u003eH\u003csub\u003e44\u003c/sub\u003eClN\u003csub\u003e2\u003c/sub\u003eO\u003csub\u003e7\u003c/sub\u003e, 759.2932).\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec14\" class=\"Section2\"\u003e \u003ch2\u003ePreparation of Compound 7\u003c/h2\u003e \u003cp\u003eA mixture of compound \u003cb\u003e1\u003c/b\u003e (100 mg, 0.17 mmol) was dissolved in CH\u003csub\u003e2\u003c/sub\u003eCl\u003csub\u003e2\u003c/sub\u003e (10 ml) and N,N׳-diisopropylcarbodiimide (DIC) (0.1 ml), 4-N,N׳-dimethylaminopyridine (DMAP) (1 mg, 0.01 mmol) and 3-Nitrobenzoic acid (10 mg, 0.06 mmol) was stirred at room temperature for 6 h. Subsequently, the mixture was poured into water (30 ml) and extracted with CH\u003csub\u003e2\u003c/sub\u003eCl\u003csub\u003e2\u003c/sub\u003e (100 ml). The organic phase was washed with water (3\u0026times;20 ml) and dried over anhydrous Na\u003csub\u003e2\u003c/sub\u003eSO\u003csub\u003e4\u003c/sub\u003e. The solvent was removed under reduced pressure and the product was purified by column chromatography using 4% MeOH in CH\u003csub\u003e2\u003c/sub\u003eCl\u003csub\u003e2\u003c/sub\u003e to yield compound \u003cb\u003e7\u003c/b\u003e (31.3 mg, 20.2%).\u003c/p\u003e \u003cp\u003e \u003cb\u003e7,12-di-(3-nitrobenzoyl)-curine (7)\u003c/b\u003e Pale yellow powder; \u003cspan class=\"InlineEquation\"\u003e\u003cspan class=\"mathinline\"\u003e\\({\\text{[\u0026alpha;]}}_{\\text{D}}^{\\text{27}}\\)\u003c/span\u003e\u003c/span\u003e -219.13 (\u003cem\u003ec\u003c/em\u003e\u0026thinsp;=\u0026thinsp;0.30, CH\u003csub\u003e2\u003c/sub\u003eCl\u003csub\u003e2\u003c/sub\u003e); IR ν\u003csub\u003emax\u003c/sub\u003e: 2933, 1747, 1612, 1530, 1503, 1435, 1348, 1252, 1205, 1110, 1050, 908, 816, 714 cm\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e; \u003csup\u003e1\u003c/sup\u003eH NMR (CDCl\u003csub\u003e3\u003c/sub\u003e, 400 MHz,): \u003cem\u003eδ\u003c/em\u003e 8.71 (1H, s, H-2\u0026prime;\u0026prime;\u0026prime;), 8.65 (1H, s, H-2\u0026prime;\u0026prime;), 8.38 (1H, d, \u003cem\u003eJ\u003c/em\u003e\u0026thinsp;=\u0026thinsp;8.0 Hz, H-4\u0026prime;\u0026prime;\u0026prime;), 8.36 (1H, d, \u003cem\u003eJ\u003c/em\u003e\u0026thinsp;=\u0026thinsp;7.2 Hz, H-4\u0026prime;\u0026prime;), 8.32 (1H, d, \u003cem\u003eJ\u003c/em\u003e\u0026thinsp;=\u0026thinsp;8.0 Hz, H-6\u0026prime;\u0026prime;\u0026prime;), 8.22 (1H, d, \u003cem\u003eJ\u003c/em\u003e\u0026thinsp;=\u0026thinsp;8.0 Hz, H-6\u0026prime;\u0026prime;), 7.60 (1H, t, \u003cem\u003eJ\u003c/em\u003e\u0026thinsp;=\u0026thinsp;8.0 Hz, H-5\u0026prime;\u0026prime;\u0026prime;), 7.55 (1H, t, \u003cem\u003eJ\u003c/em\u003e\u0026thinsp;=\u0026thinsp;8.0 Hz, H-5\u0026prime;\u0026prime;), 7.27 (1H, overlapping signal, H-14), 7.09 (1H, d, \u003cem\u003eJ\u003c/em\u003e\u0026thinsp;=\u0026thinsp;8.0 Hz, H-13), 7.01 (1H, d, \u003cem\u003eJ\u003c/em\u003e\u0026thinsp;=\u0026thinsp;8.0 Hz, H-14\u0026prime;), 6.78 (1H, overlapping signal, H-11\u0026prime;), 6.67 (1H, s, H-5), 6.67 (1H, overlapping signal, H-13\u0026prime;), 6.62 (1H, br s, H-10), 6.47 (1H, d, \u003cem\u003eJ\u003c/em\u003e\u0026thinsp;=\u0026thinsp;8.0 Hz, H-10\u0026prime;), 6.53 (1H, br s, H-5\u0026prime;), 5.52 (1H, s, H-8\u0026prime;), 3.82 (3H, s, 6-OCH\u003csub\u003e3\u003c/sub\u003e), 3.62 (1H, d, \u003cem\u003eJ\u003c/em\u003e\u0026thinsp;=\u0026thinsp;8.0 Hz, H-1), 3.52 (1H, br s, H-1\u0026prime;), 3.41, 2.94 (2H, overlapping signal, H-3), 3.37 (3H, s, 6\u0026prime;-OCH\u003csub\u003e3\u003c/sub\u003e), 3.22, 2.85 (2H, m, H-3\u0026prime;), 3.22, 2.54 (2H, overlapping signal, H-α), 3.10 (1H, m, H-4), 2.94, 2.78 (2H, overlapping signal, H- α\u0026prime;), 2.94, 2.73 (2H, overlapping signal, H-4\u0026prime;), 2.87, 2.72 (2H, d, \u003cem\u003eJ\u003c/em\u003e\u0026thinsp;=\u0026thinsp;15.2 Hz, H- 4\u0026prime;), 2.50 (1H, overlapping signal, H-4), 2.50 (3H, s, N\u0026prime;-CH\u003csub\u003e3\u003c/sub\u003e), 2.35 (3H, s, N-CH\u003csub\u003e3\u003c/sub\u003e); \u003csup\u003e13\u003c/sup\u003eC NMR (CDCl\u003csub\u003e3\u003c/sub\u003e, 100 MHz,): \u003cem\u003eδ\u003c/em\u003e 162.4 (C-7\u0026prime;\u0026prime;\u0026prime;), 162.1 (C-7\u0026prime;\u0026prime;), 155.1 (C-12\u0026prime;), 150.8 (C-6), 148.3 (C-6\u0026prime;), 148.1 (C-3\u0026prime;\u0026prime;, C-3\u0026prime;\u0026prime;\u0026prime;), 146.8 (C-12), 144.6 (C-8), 143.2 (C-7\u0026prime;), 141.3 (C-11), 139.9 (C-9), 135.7 (C-6\u0026prime;\u0026prime;, C-6\u0026prime;\u0026prime;\u0026prime;), 133.6 (C-9\u0026prime;), 132.3 (C-10\u0026prime;), 131.4 (C-1\u0026prime;\u0026prime;\u0026prime;), 130.9 (C-1\u0026prime;\u0026prime;), 130.7 (C-7), 129.7 (C-14\u0026prime;), 129.5 (C-5\u0026prime;\u0026prime;, C-5\u0026prime;\u0026prime;\u0026prime;), 128.7 (C-4a\u0026prime;), 127.7 (C-4\u0026prime;\u0026prime;\u0026prime;), 127.5 (C-4\u0026prime;\u0026prime;, C-8a\u0026prime;), 125.4 (C-14), 125.1 (C-2\u0026prime;\u0026prime;\u0026prime;), 124.9 (C-2\u0026prime;\u0026prime;), 124.6 (C-4a, C-8a), 122.5 (C-13), 122.2 (C-10), 118.3 (C-8\u0026prime;), 115.0 (C-11\u0026prime;), 114.3 (C-13\u0026prime;), 112.0 (C-5\u0026prime;), 109.0 (C-5), 64.9 (C-1\u0026prime;), 60.6 (C-1), 56.1 (6-O\u003cspan type=\"Underline\" class=\"Underline\" name=\"Emphasis\"\u003eC\u003c/span\u003eH\u003csub\u003e3\u003c/sub\u003e), 55.2 (6\u0026prime;-O\u003cspan type=\"Underline\" class=\"Underline\" name=\"Emphasis\"\u003eC\u003c/span\u003eH\u003csub\u003e3\u003c/sub\u003e), 45.5 (C-3\u0026prime;), 43.4 (C-3), 41.9 (N\u0026prime;-\u003cspan type=\"Underline\" class=\"Underline\" name=\"Emphasis\"\u003eC\u003c/span\u003eH\u003csub\u003e3\u003c/sub\u003e), 41.7 (N-\u003cspan type=\"Underline\" class=\"Underline\" name=\"Emphasis\"\u003eC\u003c/span\u003eH\u003csub\u003e3\u003c/sub\u003e), 40.6 (C-α), 39.2 (C- α\u0026prime;), 25.0 (C-4\u0026prime;), 22.0 (C-4); HR-TOF-MS (ESI\u003csup\u003e+\u003c/sup\u003e): \u003cem\u003em/z\u003c/em\u003e 893.3039 [M\u0026thinsp;+\u0026thinsp;H]\u003csup\u003e+\u003c/sup\u003e (calcd. for C\u003csub\u003e50\u003c/sub\u003eH\u003csub\u003e45\u003c/sub\u003eN\u003csub\u003e4\u003c/sub\u003eO\u003csub\u003e12\u003c/sub\u003e, 893.3028).\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec15\" class=\"Section2\"\u003e \u003ch2\u003ePreparation of Compound 8\u003c/h2\u003e \u003cp\u003eA mixture of compound \u003cb\u003e1\u003c/b\u003e (100 mg, 0.17 mmol) was dissolved in CH\u003csub\u003e2\u003c/sub\u003eCl\u003csub\u003e2\u003c/sub\u003e (10 ml) and N,N׳-diisopropylcarbodiimide (DIC) (0.1 ml), 4-N,N\u0026prime;-dimethylaminopyridine (DMAP) (1 mg, 0.01 mmol) and \u003cem\u003etrans\u003c/em\u003e-3-Nitrocinamic acid (10 mg, 0.05 mmol) was stirred at room temperature for 6 h. The mixture was poured into water (30 ml) and the solution was extracted with CH\u003csub\u003e2\u003c/sub\u003eCl\u003csub\u003e2\u003c/sub\u003e (100 ml). The organic phase was washed with water (3\u0026times;20 ml) and dried over anhydrous Na\u003csub\u003e2\u003c/sub\u003eSO\u003csub\u003e4\u003c/sub\u003e. The solvent was removed under reduced pressure and the product was purified by column chromatography using 4% MeOH in CH\u003csub\u003e2\u003c/sub\u003eCl\u003csub\u003e2\u003c/sub\u003e to yield compound \u003cb\u003e8\u003c/b\u003e (72.4 mg, 47%).\u003c/p\u003e \u003cp\u003e \u003cb\u003e7,12-di-(trans-3-nitrocinamoyl)-curine (8)\u003c/b\u003e Pale yellow powder; \u003cspan class=\"InlineEquation\"\u003e\u003cspan class=\"mathinline\"\u003e\\({\\text{[\u0026alpha;]}}_{\\text{D}}^{\\text{27}}\\)\u003c/span\u003e\u003c/span\u003e -141.40 (\u003cem\u003ec\u003c/em\u003e\u0026thinsp;=\u0026thinsp;0.30, CH\u003csub\u003e2\u003c/sub\u003eCl\u003csub\u003e2\u003c/sub\u003e); IR ν\u003csub\u003emax\u003c/sub\u003e: 2931, 2845, 1735, 1640, 1610, 1503, 1350, 1268, 1196, 1112, 974, 805, 740 cm\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e; \u003csup\u003e1\u003c/sup\u003eH NMR (CDCl\u003csub\u003e3\u003c/sub\u003e, 400 MHz,): \u003cem\u003eδ\u003c/em\u003e 8.28 (1H, s, H-2\u0026prime;\u0026prime;), 8.21 (1H, s, H-2\u0026prime;\u0026prime;\u0026prime;), 8.19 (1H, d, \u003cem\u003eJ\u003c/em\u003e\u0026thinsp;=\u0026thinsp;8.0 Hz, H-4\u0026prime;\u0026prime;), 8.18 (1H, d, \u003cem\u003eJ\u003c/em\u003e\u0026thinsp;=\u0026thinsp;8.0 Hz, H-4\u0026prime;\u0026prime;\u0026prime;), 7.78 (1H, d, \u003cem\u003eJ\u003c/em\u003e\u0026thinsp;=\u0026thinsp;7.9 Hz, H-6\u0026prime;\u0026prime;), 7.70 (1H, d, \u003cem\u003eJ\u003c/em\u003e\u0026thinsp;=\u0026thinsp;7.9 Hz, H-6\u0026prime;\u0026prime;\u0026prime;), 7.61 (1H, br d, \u003cem\u003eJ\u003c/em\u003e\u0026thinsp;=\u0026thinsp;16.4 Hz, H-7\u0026prime;\u0026prime;), 7.55 (1H, t, \u003cem\u003eJ\u003c/em\u003e\u0026thinsp;=\u0026thinsp;7.9 Hz, H-5\u0026prime;\u0026prime;), 7.54 (1H, d, \u003cem\u003eJ\u003c/em\u003e\u0026thinsp;=\u0026thinsp;7.9 Hz, H-5\u0026prime;\u0026prime;\u0026prime;), 7.45 (1H, overlapping signal, H-7\u0026prime;\u0026prime;\u0026prime;), 7.20 (1H, d, \u003cem\u003eJ\u003c/em\u003e\u0026thinsp;=\u0026thinsp;8.0 Hz, H-14), 7.04 (1H, d, \u003cem\u003eJ\u003c/em\u003e\u0026thinsp;=\u0026thinsp;8.0 Hz, H-13), 7.01 (1H, d, \u003cem\u003eJ\u003c/em\u003e\u0026thinsp;=\u0026thinsp;8.0 Hz, H-14\u0026prime;), 6.69 (1H, d, \u003cem\u003eJ\u003c/em\u003e\u0026thinsp;=\u0026thinsp;9.2 Hz, H-11\u0026prime;), 6.66 (1H, s, H-5), 6.64 (3H, overlapping signal, H-10, H-8\u0026prime;\u0026prime;, H-8\u0026prime;\u0026prime;\u0026prime;), 6.58 (2H, overlapping signal, H-5\u0026prime;, H-13\u0026prime;), 6.48 (1H, d, \u003cem\u003eJ\u003c/em\u003e\u0026thinsp;=\u0026thinsp;7.2 Hz, H-10\u0026prime;), 5.54 (1H, s, H-8\u0026prime;), 3.82 (3H, s, 6-OCH\u003csub\u003e3\u003c/sub\u003e), 3.63 (1H, overlapping signal, H-1), 3.63 (3H, s, 6\u0026prime;-OCH\u003csub\u003e3\u003c/sub\u003e), 3.46 (1H, d, \u003cem\u003eJ\u003c/em\u003e\u0026thinsp;=\u0026thinsp;10.0 Hz, H-1\u0026prime;), 3.36 (1H, m, H-3), 3.23 (1H, m, H-3\u0026prime;), 3.13 (1H, br d, \u003cem\u003eJ\u003c/em\u003e\u0026thinsp;=\u0026thinsp;11.2 Hz, H-α\u0026prime;), 3.04 (1H, m, H-4), 2.93 (1H, overlapping signal, H-3), 2.91, 2.72 (2H, overlapping signal, H-4\u0026prime;), 2.90 (1H, overlapping signal, H-α), 2.82 (1H, d, \u003cem\u003eJ\u003c/em\u003e\u0026thinsp;=\u0026thinsp;10.0 Hz, H-3\u0026prime;), 2.72, 2.51 (2H, overlapping signal, H-4), 2.67 (1H, d, \u003cem\u003eJ\u003c/em\u003e\u0026thinsp;=\u0026thinsp;13.6 Hz, H-α), 2.58 (1H, br d, \u003cem\u003eJ\u003c/em\u003e\u0026thinsp;=\u0026thinsp;11.6 Hz, H-α\u0026prime;), 2.48 (3H, s, N\u0026prime;-CH\u003csub\u003e3\u003c/sub\u003e), 2.32 (3H, s, N-CH\u003csub\u003e3\u003c/sub\u003e); \u003csup\u003e13\u003c/sup\u003eC NMR (CDCl\u003csub\u003e3\u003c/sub\u003e, 100 MHz,): \u003cem\u003eδ\u003c/em\u003e 2.58 (1H, br d, \u003cem\u003eJ\u003c/em\u003e\u0026thinsp;=\u0026thinsp;11.6 Hz, H-α\u0026prime;), 2.48 (3H, s, N\u0026prime;-CH\u003csub\u003e3\u003c/sub\u003e), 2.32 (3H, s, N-CH\u003csub\u003e3\u003c/sub\u003e); \u003csup\u003e13\u003c/sup\u003eC NMR (CDCl\u003csub\u003e3\u003c/sub\u003e, 100 MHz,): \u003cem\u003eδ\u003c/em\u003e 163.8 (C-9\u0026prime;\u0026prime;\u0026prime;), 163.3 (C-9\u0026prime;\u0026prime;), 155.2 (C-12\u0026prime;), 150.8 (C-6), 148.6 (C-6\u0026prime;, C-3\u0026prime;\u0026prime;, C-3\u0026prime;\u0026prime;\u0026prime;), 146.7 (C-12), 144.6 (C-8), 143.4 (C-7\u0026prime;\u0026prime;\u0026prime;), 143.2 (C-7\u0026prime;), 142.7 (C-7\u0026prime;\u0026prime;), 140.9 (C-9), 139.9 (C-11), 136.0 (C-1\u0026prime;\u0026prime;), 135.9 (C-1\u0026prime;\u0026prime;\u0026prime;), 133.5 (C-6\u0026prime;\u0026prime;, C-6\u0026prime;\u0026prime;\u0026prime;), 133.1 (C-9\u0026prime;), 132.2 (C-10\u0026prime;, C-7), 130.0 (C-5\u0026prime;\u0026prime;\u0026prime;), 129.9 (C-14\u0026prime;), 129.6 (C-5\u0026prime;\u0026prime;), 127.9 (C-4a\u0026prime;, C-8a\u0026prime;), 125.2 (C-14), 124.7 (C-4\u0026prime;\u0026prime;, C-4\u0026prime;\u0026prime;\u0026prime;), 124.5 (C-4a, C-8a), 122.7 (C-13), 122.5 (C-2\u0026prime;\u0026prime;, C-2\u0026prime;\u0026prime;\u0026prime;), 121.9 (C-8\u0026prime;\u0026prime;, C-8\u0026prime;\u0026prime;\u0026prime;), 120.4 (C-10), 119.6 (C-13\u0026prime;), 118.2 (C-8\u0026prime;), 115.1 (C-11\u0026prime;), 112.2 (C-5\u0026prime;), 108.9 (C-5), 64.9 (C-1\u0026prime;), 60.5 (C-1), 56.1 (6\u0026prime;-O\u003cspan type=\"Underline\" class=\"Underline\" name=\"Emphasis\"\u003eC\u003c/span\u003eH\u003csub\u003e3\u003c/sub\u003e), 55.8 (6-O\u003cspan type=\"Underline\" class=\"Underline\" name=\"Emphasis\"\u003eC\u003c/span\u003eH\u003csub\u003e3\u003c/sub\u003e), 45.6 (C-3\u0026prime;), 43.4 (C-3), 42.1 (N\u0026prime;-\u003cspan type=\"Underline\" class=\"Underline\" name=\"Emphasis\"\u003eC\u003c/span\u003eH\u003csub\u003e3\u003c/sub\u003e), 41.6 (N-\u003cspan type=\"Underline\" class=\"Underline\" name=\"Emphasis\"\u003eC\u003c/span\u003eH\u003csub\u003e3\u003c/sub\u003e), 40.4 (C-α), 38.6 (C- α\u0026prime;), 25.3 (C-4\u0026prime;), 22.0 (C-4); HR-TOF-MS (ESI\u003csup\u003e+\u003c/sup\u003e): \u003cem\u003em/z\u003c/em\u003e 945.3359 [M\u0026thinsp;+\u0026thinsp;H]\u003csup\u003e+\u003c/sup\u003e (calcd. for C\u003csub\u003e54\u003c/sub\u003eH\u003csub\u003e49\u003c/sub\u003eN\u003csub\u003e4\u003c/sub\u003eO\u003csub\u003e12\u003c/sub\u003e, 945.3341).\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec16\" class=\"Section2\"\u003e \u003ch2\u003eCell lines and culture\u003c/h2\u003e \u003cp\u003e \u003cdiv class=\"BlockQuote\"\u003e \u003cp\u003eCell lines were cultured as previously reported [\u003cspan citationid=\"CR10\" class=\"CitationRef\"\u003e10\u003c/span\u003e]. Briefly, MCF-7, MDA-MB-231, Huh-7, and human embryonic kidney 293T (HEK293T) cells were cultured in Dulbecco's Modified Eagle's medium and Ham's F-12 nutrient mixture (DMEM/F12; Gibco, Thermo Fisher Scientific) with 10% fetal bovine serum (FBS; Gibco, Thermo Fisher Scientific), 100 units/ml penicillin and 100 \u0026micro;g/mL streptomycin at 37 ◦C under a humidified 5% CO\u003csub\u003e2\u003c/sub\u003e atmosphere. The cells were sub-cultured twice per week by following the standard trypsinization protocol.\u003c/p\u003e \u003c/div\u003e \u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec17\" class=\"Section2\"\u003e \u003ch2\u003eCytotoxicity assay\u003c/h2\u003e \u003cp\u003eCell lines at a density 5x10\u003csup\u003e3\u003c/sup\u003e cells/well were seeded in a 96-well plate for 24 h. Various test compound concentrations were added to the 96-well plate and incubated for 24 hours. Ten microliters of MTT solution (5 mg/ml) were added and incubated for 2 h. Then, cell supernatants were removed, and DMSO was added to dissolve the formazan product. A microplate spectrophotometer measured light absorbent at 570 nm. The IC\u003csub\u003e50\u003c/sub\u003e was calculated by using GraphPad Prism version 8. Cisplatin (Sigma) and 0.75% DMSO (RCI Labscan) were used as a positive and negative control.\u003c/p\u003e \u003c/div\u003e"},{"header":"Declarations","content":"\u003cp\u003e \u003ch2\u003eConflict of interest:\u003c/h2\u003e \u003cp\u003eThe authors declare no competing interests.\u003c/p\u003e \u003c/p\u003e\u003ch2\u003eAcknowledgments\u003c/h2\u003e \u003cp\u003eWe acknowledge financial support from College of Allied Health Sciences, Suan Sunandha Rajabhat University. Partial support from the Center of Excellence for Innovation in Chemistry (PERCH-CIC) are gratefully acknowledged.\u003c/p\u003e"},{"header":"References","content":"\u003col\u003e\u003cli\u003e\u003cspan\u003eRukachaisirikul T, Kumjun S, Suebsakwong P, Apiratikul N, Suksamrarna A (2019) A new pyrrole alkaloid from the roots of \u003cem\u003eCissampelos pareira\u003c/em\u003e. Nat Prod Res 35:80\u0026ndash;87. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1080/14786419.2019.1614576\u003c/span\u003e\u003cspan address=\"10.1080/14786419.2019.1614576\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eMedeiros MAA, Pinho JF, De-Lira DP, Barbosa-Filho JM, Ara\u0026uacute;jo DAM, Cortes SF, Lemos VS, Cruz JS (2011) Curine, a bisbenzylisoquinoline alkaloid, blocks L-type Ca\u003csup\u003e2+\u003c/sup\u003e channels and decreases intracellular Ca\u003csup\u003e2+\u003c/sup\u003e transients in A7r5 cells. Eur J Pharmacol 669:100\u0026ndash;107. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1016/j.ejphar.2011.07.044\u003c/span\u003e\u003cspan address=\"10.1016/j.ejphar.2011.07.044\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eLeite FC, Ribeiro-Filho J, Costa HF, Salgado PRR, Calheiros AS, Carneiro AB, Almeida RN, Dias CS, Bozza PT, Piuvezam MR (2014) Curine, an alkaloid Isolated from \u003cem\u003eChondrodendron platyphyllum\u003c/em\u003e inhibits prostaglandin E2 in experimental models of inflammation and pain. Planta Med 80:1072\u0026ndash;1078. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1055/s-0034-1382997\u003c/span\u003e\u003cspan address=\"10.1055/s-0034-1382997\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eRibeiro-Filho J, Piuvezam MR, Bozza PT (2015) Anti-allergic properties of curine, a bisbenzylisoquinoline alkaloid. Molecules 20:4695\u0026ndash;4697. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi:10.3390/molecules20034695\u003c/span\u003e\u003cspan address=\"https://doi:10.3390/molecules20034695\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eRibeiro-Filho J, Leite FC, Costa HF, Calheiros AS, Torres RC, Azevedo CT, Martins MA, Dias CS, Bozza PT, Piuvezam MR (2014) Curine inhibits mast cell-dependent responses in mice. J Ethnopharmacol 155:1118\u0026ndash;1124. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1016/j.jep.2014.06.041\u003c/span\u003e\u003cspan address=\"10.1016/j.jep.2014.06.041\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eRibeiro-Filho J, Calheiros AS, Vieira-de-Abreu A, Carvalho KIM, Mendes DS, Melo CB, Martins MA, Dias CS, Piuvezam MR, Bozza PT (2013) Curine inhibits eosinophil activation and airway hyper-responsiveness in a mouse model of allergic asthma. Toxicol Appl Pharmacol 273:19\u0026ndash;26. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1016/j.taap.2013.08.015\u003c/span\u003e\u003cspan address=\"10.1016/j.taap.2013.08.015\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eGong S, Xu D, Zou F, Peng R (2017) (\u0026ndash;)-Curine induces cell cycle arrest and cell death in hepatocellular carcinoma cells in a p53-independent way. Biomed Pharmacother 89:894\u0026ndash;801. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttp://dx.doi.org/10.1016/j.biopha.2017.01.148\u003c/span\u003e\u003cspan address=\"10.1016/j.biopha.2017.01.148\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eDantas BB, Faheina-Martins GV, Coulidiati TH, Bomfim CCB, Dias CS, Barbosa-Filho JMB, Ara\u0026uacute;jo DAM (2015) J Nat Med 69:218\u0026ndash;223. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1007/s11418-014-0881-5\u003c/span\u003e\u003cspan address=\"10.1007/s11418-014-0881-5\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eKoike L, Marsaioli AJ, Reis FAM (1981) Proton and carbon-13 nuclear magnetic resonance spectroscopy and conformational aspects of the curine class of bis(benzylisoquinoline) alkaloids. J Org Chem 46:2385\u0026ndash;2389. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1021/jo00324a036\u003c/span\u003e\u003cspan address=\"10.1021/jo00324a036\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eChokchaisiri R, Chaichompoo W, Bureekaew S, Thepmalee C, Ganranoo L, Cheenpracha S, Suksamrarn A (2024) A new oligostilbenoid isolated from the stems of \u003cem\u003eOchna integerrima\u003c/em\u003e. Phytochem Lett 59:41\u0026ndash;44. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1016/j.phytol.2023.12.001\u003c/span\u003e\u003cspan address=\"10.1016/j.phytol.2023.12.001\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e\u003c/ol\u003e"},{"header":"Scheme ","content":"\u003cp\u003eSchemes 1 and 2 are available in the Supplementary Files section\u003c/p\u003e"}],"fulltextSource":"","fullText":"","funders":[],"hasAdminPriorityOnWorkflow":false,"hasManuscriptDocX":true,"hasOptedInToPreprint":true,"hasPassedJournalQc":"","hasAnyPriority":false,"hideJournal":true,"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":"researchsquare","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":true,"externalIdentity":"","sideBox":"","snPcode":"","submissionUrl":"/submission","title":"Research Square","twitterHandle":"researchsquare","acdcEnabled":true,"dfaEnabled":false,"editorialSystem":"","reportingPortfolio":"","inReviewEnabled":false,"inReviewRevisionsEnabled":true},"keywords":"Synthesis, Cytotoxicity, Ester Analogues, Cancer Therapy, (-)-Curine","lastPublishedDoi":"10.21203/rs.3.rs-4140864/v1","lastPublishedDoiUrl":"https://doi.org/10.21203/rs.3.rs-4140864/v1","license":{"name":"CC BY 4.0","url":"https://creativecommons.org/licenses/by/4.0/"},"manuscriptAbstract":"\u003cp\u003eThis study presents the synthesis and cytotoxic evaluation of ester analogues derived from (-)-curine, a natural compound isolated from the roots of \u003cem\u003eCissampelos pareira\u003c/em\u003e (Menispermaceae). The synthesis involved the preparation of mono- and di-acetylcurine, along with four other ester derivatives, through diverse chemical transformations. Structural characterization of the synthesized compounds was performed using spectroscopic techniques and high-resolution mass spectrometry. Cytotoxicity assessments were conducted across various cancer cell lines, including MCF-7, MDA-MB-231, and Huh-7, as well as non-cancerous HEK293T cells, utilizing the MTT assay. Notably, compounds \u003cb\u003e4\u003c/b\u003e and \u003cb\u003e5\u003c/b\u003e demonstrated significant cytotoxic activities superior to the parent compound \u003cb\u003e1\u003c/b\u003e and even matched or exceeded the cytotoxic effects induced by cisplatin, a conventional chemotherapeutic agent, across all tested cancer cell lines. These findings highlight the potential of compounds \u003cb\u003e4\u003c/b\u003e and \u003cb\u003e5\u003c/b\u003e as promising candidates for further development as potent cytotoxic agents in cancer therapy.\u003c/p\u003e","manuscriptTitle":"Synthesis and cytotoxic evaluation of ester analogues of (-)-curine","msid":"","msnumber":"","nonDraftVersions":[{"code":1,"date":"2024-04-03 11:10:12","doi":"10.21203/rs.3.rs-4140864/v1","editorialEvents":[{"type":"communityComments","content":0}],"status":"published","journal":{"display":true,"email":"[email protected]","identity":"researchsquare","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":true,"externalIdentity":"","sideBox":"","snPcode":"","submissionUrl":"/submission","title":"Research Square","twitterHandle":"researchsquare","acdcEnabled":true,"dfaEnabled":false,"editorialSystem":"","reportingPortfolio":"","inReviewEnabled":false,"inReviewRevisionsEnabled":true}}],"origin":"","ownerIdentity":"b964bce2-6cfa-435a-b9c0-72958b46e816","owner":[],"postedDate":"April 3rd, 2024","published":true,"recentEditorialEvents":[],"rejectedJournal":[],"revision":"","amendment":"","status":"posted","subjectAreas":[],"tags":[],"updatedAt":"2024-06-04T16:38:47+00:00","versionOfRecord":[],"versionCreatedAt":"2024-04-03 11:10:12","video":"","vorDoi":"","vorDoiUrl":"","workflowStages":[]},"version":"v1","identity":"rs-4140864","journalConfig":"researchsquare"},"__N_SSP":true},"page":"/article/[identity]/[[...version]]","query":{"redirect":"/article/rs-4140864","identity":"rs-4140864","version":["v1"]},"buildId":"qtupq5eGEP_6zYnWcrvyt","isFallback":false,"isExperimentalCompile":false,"dynamicIds":[84888],"gssp":true,"scriptLoader":[]}