PTC powder fractions of Dichrostachys glomerata Forssk. and Hibiscus sabdariffa L., sources of antioxidants with potential management of oxidative stress

PTC powder fractions of Dichrostachys glomerata Forssk. and Hibiscus sabdariffa L., sources of antioxidants with potential management of oxidative stress | 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 PTC powder fractions of Dichrostachys glomerata Forssk. and Hibiscus sabdariffa L., sources of antioxidants with potential management of oxidative stress Markusse Deli, Elie Baudelaire Njantou, Jerémy Petit, Richard Marcel Nguimbou, and 2 more This is a preprint; it has not been peer reviewed by a journal. https://doi.org/ 10.21203/rs.3.rs-6180798/v1 This work is licensed under a CC BY 4.0 License Status: Under Review Version 1 posted 22 You are reading this latest preprint version Abstract Dichrostachys glomerata fruits and Hibiscus sabdariffa calyces can be processing into good functional ingredients with antioxidant properties. The plant powder fractions obtained by pulverization and controlled sieving process (< 180 µm, 180 – 212 µm, 212 – 315 µm and ≥ 315 µm) were examined for antioxidant capacity using total antioxidant power (PAOT) technology and ferric reducing antioxidant power (FRAP). Results show that both D. glomerata and H. sabdariffa powders have high antioxidant potential and large variations in the antioxidant activity in analyzed powder fractions. The highest antioxidant activity was recorded for the 180 – 212 µm and 212 – 315 µm powder fractions of D. glomerata and H. sabdariffa , respectively. Using multiple regression, it was find that the antioxidant activity of D. glomerata and H. sabdariffa powders is attributed to polyphenols. Thus, PAOT-Liquid activity was highly correlated with total polyphenols content of all plant powders (r = 0.97, p < 0.05) and the classical FRAP assay which is often used for evaluating antioxidant capacity of food matrices (r = 0.96, p < 0.05). The antioxidant potential of D. glomerata fruits and H. sabdariffa calyces powder fractions could be useful in the management of oxidative reactions. Dichrostachys glomerata Hibiscus sabdariffa PTC powder fractions antioxidants oxidative stress Figures Figure 1 Introduction Nowadays, more attention currently given to the issues of oxidative stress and its modulation by natural antioxidants. A crucial role in health maintenance and disease prevention is based on Redox homeostasis. In fact, physiological conditions, such as aging, and in several pathological conditions, including cancer, inflammatory illnesses, cardiovascular disorders, neurodegenerative diseases, and intoxications are shown to be directly linked to an increase in oxidative stress [ 1 ]. In nutrition, the contents of antioxidants in the components of regular diets is carefully selected by many consumers and healthcare specialists. Many antioxidant supplements are available for purchase in the food market in most countries worldwide. These supplements are usually extracted from plant sources and are claimed to contain significant amounts of vitamins with antioxidants properties (vitamin A, C, and E) and trace elements such as selenium, copper, or zinc [ 2 , 3 ]. Moreover, plants are rich sources of natural antioxidants presenting excellent health benefits in the reduction of reduction of oxidative stress. They comprise a brilliant source of exogenous antioxidants, whose ranges from extremely slight to very great [ 4 ]. Interestedly, the micro micronutrients, and phytonutrients in diet, mainly the fruits and colorful vegetables, generally promote health trough antioxidant activities and have shown positive impact on enhancing immunity [ 5 , 6 , 7 ]. In addition, these natural antioxidants may act as reducing agents, free radical scavengers, singlet oxygen forming and pro-oxidant metals quenchers, localized O 2 concentration reducers, endogenous antioxidant defenses boosters, and hence avoiding damage in repair systems, or any favorable combination of the above. Therefore, they protect against oxidative stress, which in turn helps in maintaining the balance between oxidants and antioxidants levels [ 1 ]. Particulary, the D. glomerata and the calyces of H. sabdariffa fruits are two foods ingredients that fall within the category of those plants with high potential in reducing the severity of oxidative stress. Dichrostachys glomerata and H. sabdariffa are high potential antioxidant plants. Recent studies by Deli et al . [ 8 , 9 ] reported that the antioxidant properties of plant powder may be improved by PTC technology (pulverization and controlled sieving process). PTC is the actual subject of a patent application PTC/FR2011/000561 [ 10 ] and consists of concentrating the plant active principles without any solvent. Most of the method actually used to evaluate the antioxidant potential of plant powders, from either the PTC or any other technology, were based on the extraction in solvent (mostly methanol) followed by conventional measurement methods as regard: DPPH (2,2-diphenyl-1-picrylhydrazyl), and ABTS (Azinobis 3-ethylbenzothiazoline-6-sulfonic acid), FRAP (ferric reducing antioxidant power), ORAC (Oxygen Radical Absorbance Capacity). However, these methods have the disadvantage of not only being time consuming, fastidious with non-standardized protocols, but do not also reflect the various antioxidant in the plant. Compared to the known antioxidant resources the PAOT-Liquid Technology offer the possibility to effectively evaluate the antioxidant capacity, thanks to its simple, rapid and automatized protocol. In addition, PAOT-liquid technology is an easy electrochemical method for evaluating the total antioxidant capacity of food matrix [ 11 ]. The analysis is instrumental and automatic. Based on the above, total antioxidative capacity (TAC) evaluated using the PAOT technology seems to be a good indicator of the total antioxidant in plant powder. In this respect, the objective of this work was to determine the TAC of PTC powders of D. glomerata and H. sabdariffa and its correlation with the conventional method FRAP and the content in some antioxidant molecules. The aim of this manuscript is to provide with data on the potential of PTC powder fractions of D. glomerata and H. sabdariffa spices to be used as an alternative and/or complementary strategy in managing oxidative reactions, a risk factor associated to physiological conditions, and in several pathological conditions. Materials and methods Chemicals Folin-Ciocalteu’s reagent and ethanol has been supplied by WWR International, Fontenay-sous-Bois, France, while potassium ferricyanide (K 3 Fe(CN) 6 ), potassium ferrocynanide (K 4 Fe(CN) 6 ), 6-hydroxy-2,5,7,8-tetramethylchlorman-2-carboxylic acid (Trolox), ascorbic acid, α-tocopherol, butylated hydroxytoluene (BHT), butylated hydroxyanisole (BHA) were purchased from Steinheim in Germany supplied by Sigma-Aldrich GmbH. Plant material Samples were bought from vendors in different localities: dried red calyces of H. sabdariffa were purchased from local market in the Adamaoua region, while dried fruits of D. glomerata were bought in a market located in Yaoundé, central region of Cameroon. Plant materials used in this study complied with national guidelines. Each plant material was manually separated from inorganic materials, dirt, and dust particles. Plant material pulverization An electric ultra-centrifugal mill ZM 200 (Retsch, Haan, Germany) characterized with a sieve with 24-tooth rotor of 99 mm diameter and sieve with 1 mm trapezoid holes; was used to pulverize dry plant parts by impact and also the shearing size reduction principles. Dried fruits of D. glomerata and dried calyces of H. sabdariffa (50 g per batch) were pulverized at a rotor speed of 6,200 g at ambient temperature of about 20°C. This rotor speed was explained to be a compromise between grinding efficiency and local temperature increase in plant parts during grinding, as the latter is known to be activated at high rotor speed and lead to an alteration in bioactive compounds [ 8 ]. Production of PTC powder fractions The control sieving operation of PTC technology was used for powder fractions production. In this respect, each plant powder was fractionated into four particle size using an Analysette 3 Spartan sieve shaker (Fritsch, Idar-Oberstein, Germany) with 180, 212, 315 µm standard sieve sizes. Powder (100 g) was gently transferred on the first uppermost sieve and the whole set up operating by vertical vibration at 0.5 mm vibration amplitude in permanent mode for 10 min. Then after, the powder retained on each sieve was retrieved and weighed. The following powder fractions used were produced using particle sizes: < 180 µm, 180–212 µm, 212–315 µm and ≥ 315 µm. The control sample was the unsieved powder of each plant. Antioxidant analysis by using PAOT-liquid and FRAP methods were conducted on powder fractions. . Ferric Reducing Antioxidant Power assay FRAP assay was carried out according to Oyaizu [ 12 ]. This assay measures the antioxidant capacity in samples which is based on the reduction of ferric iron (Fe 3+ ) to ferrous iron (Fe 2+ ) by the presence of antioxidants in the samples. 1 mL of each powder extract or ascorbic acid solutions (at 0.02, 0.04, 0.06, 0.08 and 0.1 mg/mL) was mixed with 2.5 mL of phosphate buffer (0.2 mol/L, pH 6.6) and with equal portion, 2.5 mL, of potassium ferricyanide [0.03 mol/L, K 3 Fe(CN) 6 ]. Then, the mixture was incubated at 50°C for 20 min. 2.5 mL of 0.6 mol/L trichloroacetic acid were later on added to the mixture, followed by centrifugation for 10 min at 821 g. The supernatant of solution (2.5 mL) was mixed with 2.5 mL of distilled water and 0.5 mL of 0.1 mol/L FeCl 3 , and using a spectrophotometer (Shimadzu UV-VIS 1605, Tokyo, Japan), the absorbance was measured at a wavelength of 700 nm. Ferric reducing antioxidant power (FRAP) was expressed as ascorbic acid equivalent (AAE) per gram of dry sample. Measurement of antioxidant activity by PAOT–liquid assay PAOT-Liquid is a method of determining the antioxidant capacity of various matrices such as raw materials and processed food products, cosmetic and medicinal preparations, biological fluids, or plant extracts [ 13 , 11 ]. The PAOT-Liquid technique is actually the subject of a patent application filing (patent FR1871986; 11.28.2018). The principle is based on the measurement of electric potential variation resulting from chemical reactions between antioxidants and a free radical mediator (M ● ) as source of oxidants. This change results from the variation in the concentrations of the oxidized/reduced forms during reaction (Eq. 1) for antioxidants and reaction (Eq. 2) for oxidants: Reaction medium + AO (Antioxidant) --------> Reaction medium + AOOx (Result of the antioxidant oxidation) (Eq. 1) Reaction medium + OA (Oxidant) -------> Reaction medium + OARed (Result of the oxidant reduction) (Eq. 2) The measurement is done in a liquid medium by solubilization of sample extract in a reaction medium and then its activity is assayed directly in solution. The measurement was carried out in a reaction medium (1 mL physiological solution at pH ranging from 6.7–7.2 to simulate biological conditions during analysis), containing a molecule in a free radical state called mediator (M•). Two specific microelectrodes, one being the working electrode and the second one the reference electrode, were immersed in sample solution for a few minutes at 24–27°C. After addition of 20 µL of pure antioxidants or plant powder extracts, PAOT-liquid activity was estimated by registering electrochemical potential modifications in the reaction medium (due to variation in the concentrations of the oxidized/reduced forms during the oxidation of antioxidants and the reduction of oxidants). Antioxidant activity was calculated according to the following formula: \(\:\text{A}\text{n}\text{t}\text{i}\text{o}\text{x}\text{y}\text{d}\text{a}\text{n}\text{t}\:\text{a}\text{c}\text{t}\text{i}\text{v}\text{i}\text{t}\text{y}=\left(\frac{\text{E}\text{P}\:\text{p}\text{r}\text{o}\text{d}\text{u}\text{c}\text{t}\:\:-\:\text{E}\text{P}\:\text{c}\text{o}\text{n}\text{t}\text{r}\text{o}\text{l}\:}{\text{E}\text{P}\:\text{c}\text{o}\text{n}\text{t}\text{r}\text{o}\text{l}\:}\right)\times\:\:100\%\:\) (Eq. 3) Where EP control is the electrochemical potential at time 0 and EP product is the electrochemical potential obtained after 10 min registration of tested antioxidants or powder samples. Pure antioxidants were equally tested as references and results expressed on their basis: trolox, ascorbic acid, α-tocopherol, BHT and BHA. Statistical tools used in the analysis of data Results were expressed as mean ± standard deviation of at least three determinations (n = 3). Data were subjected to analysis of variance (ANOVA) to determine if there were statistically significant ( p < 0.05) differences among the powder fractions. Duncan multiple range test was used to determine the difference between two subsequent samples. Correlations and multilinear regression analysis between antioxidant activity of plant powders and bioactive molecules, including PAOT-liquid technology, FRAP, total phenols, flavonoid, zinc, copper and vit C contents reported in earlier publications (8, 9) was conducted using the regression program in Statgraphics centurion version 15.1. For regression models, the antioxidant activity was calculated as a function of bioactive molecules contents. Thus, the contribution of bioactive molecule contents was determined. Results and discussion Ferric reducing antioxidant power The FRAP assay measures the antioxidant effect of any substance in the reaction medium as reducing ability. As shown in Table 1 , the ferric reducing antioxidant power varied significantly ( p < 0.05) with plant species, although values of both D. glomerata and H. sabdariffa could be considered high. Meanwhile, the FRAP activity was higher (60.03 ± 0.75 mg AAE/g DW) for the unsieved D. glomerata powder than for unsieved H. sabdariffa powder (38.96 ± 0.57 mg AAE/g DW). Looking to the powder fractions, a significant difference ( p < 0.05) were denoted between the different fractions of the same plant. FRAP assay revealed the highest antioxidant activity for the 180–212 µm fraction of D. glomerata powder and the fraction 212–315 µm size class for H. sabdariffa . Results in literature reported that the antioxidant activity of D. glomerata was particularly high as compared to many plants such as Fagara leprieuri , Scorodophleus zenkeri (fruit), Tetrapleura tetraptera and Hua gabonii (fruit) [ 14 , 15 ], thus supporting the antioxidative potential of this plant. In addition, literature also revealed the potential of sieved fractionation on the improvement of antioxidant properties of food powders. In particular, the fraction with the highest activity found in this study had previously been found to be richer in antioxidant compounds, especially in phenolic compounds, DPPH and ABTS antiradical properties. Globally results indicated an improvement in antioxidant capacity of both plant powders with PTC technology. Table 1 FRAP antioxidant activity (mg AAE/g DW) of powder fractions and unsieved powder of D. glomerata fruits and H. sabdariffa calyces Powder fractions D. glomerata H. sabdariffa < 180 µm 59.96 ± 2.70 c 39.46 ± 0.65 b 180–212 µm 63.43 ± 0.20 d 38.67 ± 0.13 b 212–315 µm 53.91 ± 0.90 b 40.99 ± 0.53 c ≥ 315 µm 40.62 ± 2.08 a 33.83 ± 0.96 a Unsieved 60.03 ± 0.75 c 38.96 ± 0.57 b For each plant, means ± standard deviations (n = 3) followed by the same superscripted letter were not significantly different (p < 0.05 ) Total antioxidant power (PAOT) The PAOT of D. glomerata and H. sabdariffa powders, expressed in mg equivalent of antioxidant references per gram of dry sample, is shown in Fig. 1 (A and B). The plant powders with highest PAOT antioxidant capacity was found to be D. glomerata compared to H. sabdariffa , irrespective of the fraction. PAOT of unsieved powder from D. glomerata fruits was 45.95 mg trolox equivalents/g DW, while PAOT expressed on the basis of ascorbic acid, BHA, BHT and α-tocopherol equivalent were 27.3, 70.7, 72.0 and 48.9 mg/g DW, respectively. For H. sabdariffa calyces, the PAOT were 30.5, 18.1, 47.0, 47.8 and 32.5 mg of trolox, ascorbic acid, BHA, BHT and α-tocopherol, respectively. It clearly appeared from these data that the fractions with high PAOT activity were 180–212 µm and 212–315µm for D. glomerata and H. sabdariffa , respectively. Similar antioxidant profile is reported above for FRAP, suggesting the pertinence of the PAOT technology. Considering the increasing need to find effective natural antioxidants agents and the role of diet in reducing oxidant stress, D. glomerata and H. sabdariffa powders are markedly to being considered as sources of antioxidant agents. Then, considering PTC fractions from D. glomerata fruits and H. sabdariffa calyces to be used as inexpensive medicinal antioxidants such as vitamin C (ascorbic acid) and vitamin E, and according to daily recommended dietary allowance, it appeared that the daily need of vit C or vit E may be covered by these powders. The equivalent quantities of both plant fractions required to fill the daily needs of vitamin C (vitamin C daily need is 90 mg and 75 mg/day for male and female adults, respectively) and α-tocopherol (α-tocopherol daily recommended dietary allowance is 10 mg and 8 mg for male and female adults, respectively) [ 16 ] are shown in Table 2 . In this respect, approximately 2.4 to 4.5 g of D. glomerata powder and 4.3 to 5.1 g H. sabdariffa powder are necessary to fill the daily needs of vitamin C in male adults. Similarly, for α-tocopherol, 0.16 to 0.28 g D. glomerata and 0.28 to 0.33 g of H. sabdariffa powders are needed. Thus, PTC powder fractions of these two spices can potentially be offered in teas, foods and/or dietary supplements. Looking to the powder fractions from D. glomerata and H. sabdariffa separately, significant differences ( p < 0.05) were denoted between the different fractions and unsieved powder on the quantity necessary to fill the daily needs of vitamin C and that of α-tocopherol. The minimal powder quantity was found in the fractions 180–212 µm and 212–315 µm for D. glomerata and H. sabdariffa, r espectively. Indeed, these intermediate size class possessed the highest total antioxidant potential. Powder fraction 180–212 µm of D. glomerata exhibited a PAOT antioxidant power of 36.6 mg AAE/g DW. The equivalent PAOT antioxidant power for the other standards compounds were 94.85 mg BHA equivalent/g DW, 96.53 mg BHT equivalent/g DW, 65.56 mg α-tocopherol equivalent/g DW and 61.61 mg trolox equivalent/g DW. As regards H. sabdariffa powder, 212–315 µm fraction showed the highest PAOT antioxidant activity of 34.49 mg trolox equivalent/g DW. According to our previous results [ 8 ], the intermediate 212–315 µm fraction of H. sabdariffa and 180–212 µm fraction of D. glomerata had been found to be rich in antioxidant compounds, especially in phenolic compounds and consequently had the highest antioxidant properties, as measured by DPPH and ABTS methods. It also suggests that antioxidative molecules including phenols, flavonoids, tannins, minerals and vitamin C functioned in synergy to confer to the powder their antioxidant properties. This is consistent with the fact that antioxidant capacity of plant products is generally attributed to radical scavenging activity of phenolic compounds. In fact, it was reported in our previous study [ 8 ], that phenolic compounds significantly contributed to the DPPH and ABTS radicals scavenging activities of investigated plant powders. However, the phenolic components are not the only contributor of antioxidant capacity; vitamin C and mineral elements were equally reported in relatively high quantity in finer powder fractions (< 180 µm and 180–212 µm) of D. glomerata. Table 2 Equivalent quantity of powders from D. glomerata and H. sabdariffa required to fill the daily needs of vitamin C and α-tocopherol for healthy individuals (≥ 19 years of age) male and female. Powder fractions D. glomerata H. sabdariffa Ascorbic acid (g) α-tocopherol (g) Ascorbic acid (g) α-tocopherol (g) < 180 µm 2.7–2.2 0.17–0.14 4.7–3.9 0.30–0.24 180–212 µm 2.4–2.0 0.16–0.13 4.7 − 3.9 0.30–0.24 212–315 µm 3.2–2.7 0.21–0.17 4.3–3.7 0.28–0.22 ≥ 315 µm 4.5–3.8 0.28–0.23 5.1–4.3 0.33–0.26 Unsieved 3.2–2.7 0.21–0.17 5.0–4.1 0.31–0.25 Relationship between bioactive substances and antioxidant properties In order to evaluate the suitability and reliability of the essay methods used to determine the total antioxidant potential of D. glomerata and H. sabdariffa powders, we performed Pearson’s correlation on the values of bioactive molecules and antioxidant constituents reported in our previous studies [ 8 , 9 ] and under investigation. The analysis is based on link between the antioxidant compounds (phenolic, Zn, Cu, total carotenoids and vit C contents) and the antioxidant capacity of the plant powders (PAOT, FRAP, DPPH and ABTS assays). As shown in Table 3 , FRAP and PAOT were significantly and negatively correlated with DPPH and ABTS. The DPPH and ABTS were expressed as concentration of powder that inhibited 50% of the radical. Then negative correlation with DPPH and ABTS were expected and indicated that all antioxidant tests were intercorrelated. The DPPH was strongly correlated with ABTS (r = 0.82, p < 0.05). PAOT and FRAP were all strongly correlated with total phenolics (r = 0.95 and r = 0.97, p < 0.05), while DPPH and ABTS were negatively correlated with total phenolics (r = -0.86, r = -0.91, respectively). The strong correlation between the total antioxidant capacity assayed by DPPH, ABTS, FRAP and PAOT-liquid methods and total phenolics indicated that the phenolic compounds could play an important role in antioxidant property of these plant powders. Moreover, the correlation between vit C versus PAOT-liquid, FRAP, DPPH and ABTS were also significant and higher (r = 0.91, r = 0.83, r = -0.79, r = -0.87, respectively), suggesting that the antioxidant activity of D. glomerata and H. sabdariffa powders were equally dependent on the vit C. Minerals were also found to contribute to the antioxidant property of the powders either negatively or positively. In fact, while powder fractions with high copper content exhibited high antioxidant activities (r > 0.73), inverse observations were made for zinc. This observation is probably a result of the negative correlation, although non-significant, between the concentration of Zn 2+ and Cu 2+ in the plant powders (r = -0.33). In addition, literature reported that while nonenzymatic antioxidants such as α-tocopherol, vit C and phenolics can prevent or slow oxidation by interacting directly with radicals or carbon-centered free radicals, zinc is known as non-redox active and its antioxidant role is mostly seen in vivo as cofactors of superoxide dismutase [ 17 ]. Owing to the similarities in their coordination chemistry, it is also reported that Zn 2+ can compete with Cu 2+ for certain types of binding sites, and thereby suppress their ability to transfer electron in a particular environment [ 17 ]. These correlations contrasted with the theory behind both minerals, as Cu 2+ is generally thought of as a prooxidant that causes free radical damage and lipid peroxidation. Whatever the case, the present result pointed out the opposed role of both minerals in the in vitro antioxidant capacity of powder, one being antioxidant the other being prooxidant. The role of phenolic compounds and vit C as antioxidant of plant origin including herbs and medicinal plants is well documented [ 18 , 19 ]. Table 3 Pearson’s correlation coefficients between the four assays (PAOT, FRAP, DPPH and ABTS) and between the assays and antioxidant constituents (total phenols, flavonoids, vit C, total carotenoids, zinc and copper) Variables TP FL Zinc Copper Vit C TC DPPH ABTS FRAP PAOT TP 1 FL 0.94 1 Zinc -0.75 -0.77 1 Copper 0.74 0.81 -0.32 1 Vit C 0.91 0.92 -0.63 0.84 1 TC -0.70 -0.73 0.91 -0.33 -0.63 1 DPPH -0.86 -0.76 0.44 -0.83 -0.79 0.37 1 ABTS -0.91 -0.91 0.63 -0.82 -0.87 0.60 0.82 1 FRAP 0.95 0.92 -0.67 0.73 0.82 -0.58 -0.84 -0.90 1 PAOT 0.97 0.91 -0.62 0.75 0.91 -0.54 -0.83 -0.90 0.96 1 TP: total phenols, FL: flavonoids, TC: total carotenoids In order to analyze the contributions of total phenols, zinc, copper and vit C to the antioxidant activity of D. glomerata and H. sabdariffa powders as well as their synergistic effects. Multiple linear regression was employed to construct multiple linear models with antioxidant activity (PAOT-liquid, FRAP, DPPH and ABTS) as the dependent variable (Y) and total phenols, flavonoids, zinc, copper and vit C, as the dependent variables (X). Stepwise elimination of variables (if p > 0.05) and insertion of variables (if p < 0.05) were performed to establish the best fit model that will exactly represent the influence of bioactive molecules on the antioxidant activities of investigated plant powders. As presented in Table 4 , model 1 was the best fitted model for DPPH, indicating that DPPH was significantly correlated linearly with total phenols, copper, vit C and total carotenoids (R² = 0.90, p < 0.05), of which 90% of DPPH variation showed dependence on these antioxidant compounds. The fit model 2 for ABTS was also linearly correlated with total phenols, copper, vit C and total carotenoids (R² = 0.90, p < 0.05) and the 90% variation of ABTS values was attributed to total phenols, copper, vit C and total carotenoids without significant contribution from zinc. Similarly, model 3 showed that FRAP was also significantly linearly correlated with total phenols, copper, vit C and total carotenoids (R² = 0.94, p < 0.05) and without zinc. Then, total phenols, copper, vit C and total carotenoids may be responsible for the 94% variation of FRAP. Finally, model 4 for PAOT linearly correlated with total phenols, copper, vit C and total carotenoids (R² = 0.90, p < 0.05) and they explain the 90% variation of PAOT. Based on the current results, the highest antioxidant activity observed in the DPPH, ABTS, FRAP and PAOT assays was due to total phenols, copper, vit C and total carotenoids, suggesting they are the most important bioactive molecules. Moreover, total phenolics seemed to have a higher correlation with antioxidant activity than others molecules. The phenolic compounds are major antioxidants in plant products, and their antioxidant activity have been demonstrated in previous studies [ 20 , 8 ]. Behind phenolic compounds, vit C and carotenoids are antioxidant constituents of natural plant product. Phenolic antioxidants act by chelating metal ions, adsorbing and neutralizing free radicals, quenching singlet and triplet oxygen, or decomposing peroxides, while carotenoids are known to be very efficient physical and chemical quenchers of singlet oxygen (1O 2 ), as well as potent scavengers of other reactive oxygen species [ 21 ]. In addition, based on its redox potential and its free radical intermediate, vit C is a chemical reducing agent (antioxidant) in many intracellular and extracellular reactions, and has an ability to donate electrons to ROS to make it stable. The results are in accordance with other works presenting phenolic compounds, vit C and carotenoids as major antioxidant constituent plants, and there are directly associated with the antioxidant activity [ 22 , 23 , 18 ]. Table 4 Multiple linear regression models of PAOT, FRAP, DPPH and ABTS with total phenols, flavonoids, vit C, total carotenoids, zinc and copper contents. Dependent variables ( Y ) Independent variables ( X ) Model numbers and regression equations R 2 Significant ( p value) DPPH Total phenols ( X 1 ), Zinc ( X 2 ), copper ( X 3 ), Vit C ( X 4 ), Total carotenoïds ( X 5 ) (1) Y = 13.586–0.783 X 1 – 54.307 X 3 + 2.171 X 4 – 0.063 X 5 0.90 0.033 ABTS (2) Y = 83.599–3.148 X 1 – 299.735 X 3 + 7.585 X 4 + 0.146 X 5 0.90 0.040 FRAP (3) Y = 75.746 + 0.507 X 1 + 15.393 X 3 – 1.169 X 4 + 0.029 X 5 0.94 0.011 PAOT (4) Y = − 25.648 + 0.428 X 1 – 10.141 X 3 + 0.636 X 4 + 0.044 X 5 0.90 0.002 Antioxidant molecules such as polyphenols, vit C and carotenoids from D. glomerata and H. sabdariffa may not only exert their antioxidant effect by acting directly on scavenging ROS, but also by alternating their effect and inducing the expression of other antioxidant enzymes. Our recent study reported that the individual PTC powder fraction from D. glomerata at the dose of 250 mg/kg body weight increased levels of superoxide dismutase and catalase activities in rats, and consequently reduce malondialdehyde production in the liver and plasma [ 9 ]. D. glomerata are commonly used as spices and the potential adverse effects of D. glomerata fruits pod extract at dose levels of 100, 1000 and 2500 mg/kg body weight/day for 90-days, in a sub-chronic toxicity study and in genotoxicity, no-observed-adverse-effect level for D. glomerata was observed [ 24 ]. Anti-Inflammatory activities of D. glomerata fruits in rats was also reported [ 25 ]. Similar important antioxidative and anti-inflammatory activities of H. sabdariffa have been equally reported in cell, animal and human models [ 26 ]. More precisely a consumption of 125 mg/kg/day of H. sabdariffa polyphenols by human patients for four weeks decreased the majority of the inflammatory and oxidative stress biomarkers analyzed, as well as increased the anti-inflammatory hormone adiponectin [ 27 ]. H. sabdariffa calyces are frequently consumed by populations as drink, and toxicity studies revealed no risks on immune system, liver and kidney functions as well as serum enzymes [ 28 ]. All these studies support the hypothesis formulated in the present study, that the investigated powder fractions from D. glomerata fruits and H. sabdariffa calyces can prevent and ameliorating oxidative stress in viral infection such in COVID-19. The fatality of COVID-19 is mainly due to the severity of the symptoms including coagulopathy, inflammation and immune depression [ 29 ]. Although this is still under investigation, there are many evidences that oxidative stress is a probable cause of multi organ failure in the COVID-19 [ 29 ]. Studies by Van der Brand et al. [ 30 ] reported and favored ROS levels and disturbance of antioxidant defense during SARS-CoV infection in animal models under experimentation of severe acute respiratory syndrome. In addition, Smith et al. [ 31 ] reported during the onset of severe lung injury in SARS-CoV infected patients, an activation of oxidative stress machinery, coupled with innate immunity and activated transcription factors, and finally a serious proinflammatory host response. Lin et al. [ 32 ] showed that SARS-CoV 3 CLpro (a viral protease) caused a significant increase in ROS production in HL-CZ cells, which in turn, is involved in 3CL pro-induced cell apoptosis. Conclusion The present study aims to show the antioxidant potentials of PTC powder fractions from D. glomerata fruits and H. sabdariffa calyces, ingredients known as a good source of antioxidant that could be use in the management oxidative reactions. PAOT-liquid technology and FRAP assay were used to measure the antioxidant activity of the powder fractions. Correlation between the antioxidant activities determined by these methods and bioactive molecules in powders was performed. Results show that both D. glomerata and H. sabdariffa powders have high antioxidant potential which varies with the powder fraction. The highest antioxidant activity was recorded for the 180–212 µm and 212–315 µm powder fractions of D. glomerata powder and H. sabdariffa , respectively. The study reinforces the general knowledge that the antioxidant activity of D. glomerata and H. sabdariffa powders is attributed to their antioxidant molecules and in particular phenolics, vit C, and copper. The PAOT-liquid activity is highly correlated with these compounds and to the classical FRAP assay which is often used for evaluating antioxidant capacity of food matrices. The daily consumption of 2.0-2.5 g and 3.7–4.3 g powder fractions 180–212 µm and 212–315 µm from D. glomerata fruits and H. sabdariffa calyces is sufficient to cover the daily needs of vit C for an adult, useful to manage oxidative reactions associated in Covid-19 disease. These quantities not only have the advantage to cover the daily needs of α-tocopherol, but also contribute to the copper and zinc which interfere with virus invasion. Abbreviations PTC: pulverization and controlled sieving process PAOT: total antioxidant power BHA: BHT: ABTS: Azinobis 3-ethylbenzothiazoline-6-sulfonic acid AAE: ascorbic acid equivalent AO: Antioxidant ANOVA: analysis of variance BHT: butylated hydroxytoluene BHA: butylated hydroxyanisole DPPH: 2,2-diphenyl-1-picrylhydrazyl DW: dry weight FRAP: ferric reducing antioxidant power ORAC: Oxygen Radical Absorbance Capacity TAC: total antioxidative capacity Declarations Availability of data and materials The dataset supporting the conclusions of this article is at the disposal of the corresponding author and remains available when needed Conflict interest and funding The authors declare no potential conflicts of interest. The study was funded by the Region Grand Est (France) and Agence Universitaire de la Francophonie (AUF, Francophone University Association) (project n° S0020ADM10607L), who did not have any role in the different parts of the study Ethics and consent No experience has been performed on patients or animals in this study. Consent to Participate declaration: Not applicable Consent to Publish declaration: Not applicable Clinical trial number : Not applicable.’ References Sharifi-Rad, J.; Sharifi-Rad, M.; Salehi, B.; Iriti, M.; Roointan, A.; Mnayer, D.; Soltani-Nejad, A.; Afshari, A. In vitro and in vivo assessment of free radical scavenging and antioxidant activities of Veronica persica Poir. Cell. Mol. Biol. 2018, 64, 57–64. Lo Pandey, K.B.; Rizvi, S.I. Plant polyphenols as dietary antioxidants in human health and disease. Oxid. Med. Cell. Longev. 2009, 2 , 270–278. Erol N, Saglam L, Saglam YS, Erol H.S, Altun S and Aktas MS. 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Food Chem Toxicol. 2014; 69: 120–131.Doi: 10.1016/j.fct.2014.03.045 . Atsang AAG., Dzeufiet DPD., Foyet HS., Nana P., Sokeng DS., Dimo T. and Kamtchouing P. Analgesic and Anti-Inflammatory Activities of Dichrostachys glomerata (Forssk.) Hutch. Fruits Methanolic Extract in Rats. J Phys Pharm Adv 2012, 2(8): 269–276. Doi: 10.1155/2012/135379 . Lopez M, Fernandez-Arroyo S, Perez-Sanchez A, Barrajon-Catalan E, Beltran-Debon R, Menendez JA, Alonso-Villaverde C, Segura-Carretero A, Joven J, Micol V. Synergism of plant-derived polyphenols in adipogenesis: Perspectives and implications. Phytomedicine. 2012; 19(3–4): 253–261. Doi: 10.1016/j.phymed.2011.12.001 . Joven J, March I, Espinel E, Fernandez-Arroyo S, Rodriguez-Gallego E, Aragones G, Beltran-Debon R, Alonso-Villaverde C, Rios L, Martin-Paredero V. Hibiscus sabdariffa extract lowers blood pressure and improves endothelial function. Mol. Nutr. Food Res. 2014; 58(6): 1374–1378.Doi: 10.1002/mnfr.201300774 . Tazoho GM, IGouado I, Ndomou M, Bonsi ST, Wamba YM, Agbor EE. Clinical, Hematological and Biochemical Health Benefit Effects of Hibiscus sabdariffa Lin Dried Calyces Beverage in Human. Food Nutri Sci. 2016; 7(5): 383–395. Doi: 10.4236/FNS.2016.75040 . Livan D.-R., Mesta F. Oxidative Stress as Key Player in Severe Acute Respiratory Syndrome Coronavirus (SARS-CoV) Infection. Archive of Medical Science. 2020; 51: 384–387. Doi: 10.1016/j.arcmed.2020.04.019 . Van den Brand JMA, Haagmans BL, van Riel D, et al. The pathology and pathogenesis of experimental severe acute respiratory syndrome and influenza in animal models. J Comp Pathol. 2014; 151(1): 83–112. Doi: 10.1016/j.jcpa.2014.01.004 . Smith JT, Willey NJ, Hancock JT. Low dose ionizing radiation produces too few reactive oxygen species to directly affect antioxidant concentrations in cells. Biol Lett. 2012; 8:594–597. Doi: 10.1098/rsbl.2012.0150 . Lin CW, Lin KH, Hsieh TH, et al. 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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-6180798","acceptedTermsAndConditions":true,"allowDirectSubmit":false,"archivedVersions":[],"articleType":"Research Article","associatedPublications":[],"authors":[{"id":458126717,"identity":"9a8646f9-5406-414f-b393-246c0bc0bb63","order_by":0,"name":"Markusse Deli","email":"data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAAZAAAAAyAQMAAABI0h/eAAAABlBMVEX///8AAABVwtN+AAAACXBIWXMAAA7EAAAOxAGVKw4bAAAA10lEQVRIie3RPQrCMBTA8ciT55LYtSK2JxAqgS71MIqQHsNOz8kjeA1xLGRVuuqmCJ0UnAShgq0uTv3YBPOH5GXIDwJhzGT6zeC9ugAxa0XFOa5JEHDyIfmsSRj36pHhYneWPAsc7PC7/diMHYbiWEr8bShngkKJINa95VZJhh2vnMQKtIj0lHJiC9LTyKXyh/lJCppnek7A096zIIgVZK9gxlFPEDj2RT2SwmhF4YgAZTAgJbGSJArsSxa4lqVPhyuNHauKfNe2i70ByP/z1uS2yWQy/U8vg6U58tmCxu0AAAAASUVORK5CYII=","orcid":"","institution":"University of Maroua","correspondingAuthor":true,"prefix":"","firstName":"Markusse","middleName":"","lastName":"Deli","suffix":""},{"id":458126718,"identity":"967d1592-ee47-45ac-810a-968b0f7e1aa8","order_by":1,"name":"Elie Baudelaire Njantou","email":"","orcid":"","institution":"University of Ngaoundéré","correspondingAuthor":false,"prefix":"","firstName":"Elie","middleName":"Baudelaire","lastName":"Njantou","suffix":""},{"id":458126719,"identity":"086b58c3-94ef-421c-b087-e3c8a9f386a6","order_by":2,"name":"Jerémy Petit","email":"","orcid":"","institution":"University of Lorraine","correspondingAuthor":false,"prefix":"","firstName":"Jerémy","middleName":"","lastName":"Petit","suffix":""},{"id":458126720,"identity":"d6f1ae08-904c-4373-9edf-a0b3dcbcd8fd","order_by":3,"name":"Richard Marcel Nguimbou","email":"","orcid":"","institution":"University of Ngaoundéré","correspondingAuthor":false,"prefix":"","firstName":"Richard","middleName":"Marcel","lastName":"Nguimbou","suffix":""},{"id":458126721,"identity":"8840ac17-0313-401e-8167-6ec10ac5a72f","order_by":4,"name":"Yanou Nicolas Njintang","email":"","orcid":"","institution":"University of Ngaoundéré","correspondingAuthor":false,"prefix":"","firstName":"Yanou","middleName":"Nicolas","lastName":"Njintang","suffix":""},{"id":458126722,"identity":"4bfa86a4-af37-4d18-b1fa-5174351c3956","order_by":5,"name":"Joël Scher","email":"","orcid":"","institution":"University of Lorraine","correspondingAuthor":false,"prefix":"","firstName":"Joël","middleName":"","lastName":"Scher","suffix":""}],"badges":[],"createdAt":"2025-03-07 20:53:08","currentVersionCode":1,"declarations":"","doi":"10.21203/rs.3.rs-6180798/v1","doiUrl":"https://doi.org/10.21203/rs.3.rs-6180798/v1","draftVersion":[],"editorialEvents":[],"editorialNote":"","failedWorkflow":false,"files":[{"id":83074177,"identity":"0657f9c1-978b-4b44-9886-7c33c5b32f73","added_by":"auto","created_at":"2025-05-19 17:44:19","extension":"png","order_by":1,"title":"Figure 1","display":"","copyAsset":false,"role":"figure","size":273931,"visible":true,"origin":"","legend":"\u003cp\u003ePAOT-liquid antioxidant activity of powder fractions and unsieved powder of (\u003cstrong\u003eA\u003c/strong\u003e)\u003cem\u003eD. glomerata\u003c/em\u003e fruits and (\u003cstrong\u003eB\u003c/strong\u003e) \u003cem\u003eH. sabdariffa \u003c/em\u003ecalyces\u003cem\u003e.\u003c/em\u003e \u003cem\u003eBHT: butylated hydroxytoluene, BHA: butylated hydroxyanisole. The values are means ± standard deviations of triplicate analyses. Columns labeled with different letters are significantly different (p \u003c/em\u003e\u0026lt; 0.05\u003cem\u003e) by Duncan test\u003c/em\u003e\u003c/p\u003e","description":"","filename":"1.png","url":"https://assets-eu.researchsquare.com/files/rs-6180798/v1/8309a6b096f754d8ed223629.png"},{"id":83076086,"identity":"d7e92e3c-a827-41a6-9741-dc87bbded28b","added_by":"auto","created_at":"2025-05-19 18:08:22","extension":"pdf","order_by":0,"title":"","display":"","copyAsset":false,"role":"manuscript-pdf","size":1309456,"visible":true,"origin":"","legend":"","description":"","filename":"manuscript.pdf","url":"https://assets-eu.researchsquare.com/files/rs-6180798/v1/e586079a-53f1-4515-833a-638c3da4ce99.pdf"}],"financialInterests":"No competing interests reported.","formattedTitle":"PTC powder fractions of Dichrostachys glomerata Forssk. and Hibiscus sabdariffa L., sources of antioxidants with potential management of oxidative stress","fulltext":[{"header":"Introduction","content":"\u003cp\u003eNowadays, more attention currently given to the issues of oxidative stress and its modulation by natural antioxidants. A crucial role in health maintenance and disease prevention is based on Redox homeostasis. In fact, physiological conditions, such as aging, and in several pathological conditions, including cancer, inflammatory illnesses, cardiovascular disorders, neurodegenerative diseases, and intoxications are shown to be directly linked to an increase in oxidative stress [\u003cspan citationid=\"CR1\" class=\"CitationRef\"\u003e1\u003c/span\u003e].\u003c/p\u003e \u003cp\u003eIn nutrition, the contents of antioxidants in the components of regular diets is carefully selected by many consumers and healthcare specialists. Many antioxidant supplements are available for purchase in the food market in most countries worldwide. These supplements are usually extracted from plant sources and are claimed to contain significant amounts of vitamins with antioxidants properties (vitamin A, C, and E) and trace elements such as selenium, copper, or zinc [\u003cspan citationid=\"CR2\" class=\"CitationRef\"\u003e2\u003c/span\u003e, \u003cspan citationid=\"CR3\" class=\"CitationRef\"\u003e3\u003c/span\u003e]. Moreover, plants are rich sources of natural antioxidants presenting excellent health benefits in the reduction of reduction of oxidative stress. They comprise a brilliant source of exogenous antioxidants, whose ranges from extremely slight to very great [\u003cspan citationid=\"CR4\" class=\"CitationRef\"\u003e4\u003c/span\u003e]. Interestedly, the micro micronutrients, and phytonutrients in diet, mainly the fruits and colorful vegetables, generally promote health trough antioxidant activities and have shown positive impact on enhancing immunity [\u003cspan citationid=\"CR5\" class=\"CitationRef\"\u003e5\u003c/span\u003e, \u003cspan citationid=\"CR6\" class=\"CitationRef\"\u003e6\u003c/span\u003e, \u003cspan citationid=\"CR7\" class=\"CitationRef\"\u003e7\u003c/span\u003e]. In addition, these natural antioxidants may act as reducing agents, free radical scavengers, singlet oxygen forming and pro-oxidant metals quenchers, localized O\u003csub\u003e2\u003c/sub\u003e concentration reducers, endogenous antioxidant defenses boosters, and hence avoiding damage in repair systems, or any favorable combination of the above. Therefore, they protect against oxidative stress, which in turn helps in maintaining the balance between oxidants and antioxidants levels [\u003cspan citationid=\"CR1\" class=\"CitationRef\"\u003e1\u003c/span\u003e].\u003c/p\u003e \u003cp\u003eParticulary, the \u003cem\u003eD. glomerata\u003c/em\u003e and the calyces of \u003cem\u003eH. sabdariffa\u003c/em\u003e fruits are two foods ingredients that fall within the category of those plants with high potential in reducing the severity of oxidative stress. \u003cem\u003eDichrostachys glomerata\u003c/em\u003e and \u003cem\u003eH. sabdariffa\u003c/em\u003e are high potential antioxidant plants. Recent studies by Deli \u003cem\u003eet al\u003c/em\u003e. [\u003cspan citationid=\"CR8\" class=\"CitationRef\"\u003e8\u003c/span\u003e, \u003cspan citationid=\"CR9\" class=\"CitationRef\"\u003e9\u003c/span\u003e] reported that the antioxidant properties of plant powder may be improved by PTC technology (pulverization and controlled sieving process). PTC is the actual subject of a patent application PTC/FR2011/000561 [\u003cspan citationid=\"CR10\" class=\"CitationRef\"\u003e10\u003c/span\u003e] and consists of concentrating the plant active principles without any solvent. Most of the method actually used to evaluate the antioxidant potential of plant powders, from either the PTC or any other technology, were based on the extraction in solvent (mostly methanol) followed by conventional measurement methods as regard: DPPH (2,2-diphenyl-1-picrylhydrazyl), and ABTS (Azinobis 3-ethylbenzothiazoline-6-sulfonic acid), FRAP (ferric reducing antioxidant power), ORAC (Oxygen Radical Absorbance Capacity). However, these methods have the disadvantage of not only being time consuming, fastidious with non-standardized protocols, but do not also reflect the various antioxidant in the plant. Compared to the known antioxidant resources the PAOT-Liquid Technology offer the possibility to effectively evaluate the antioxidant capacity, thanks to its simple, rapid and automatized protocol. In addition, PAOT-liquid technology is an easy electrochemical method for evaluating the total antioxidant capacity of food matrix [\u003cspan citationid=\"CR11\" class=\"CitationRef\"\u003e11\u003c/span\u003e]. The analysis is instrumental and automatic. Based on the above, total antioxidative capacity (TAC) evaluated using the PAOT technology seems to be a good indicator of the total antioxidant in plant powder.\u003c/p\u003e \u003cp\u003eIn this respect, the objective of this work was to determine the TAC of PTC powders of \u003cem\u003eD. glomerata\u003c/em\u003e and \u003cem\u003eH. sabdariffa\u003c/em\u003e and its correlation with the conventional method FRAP and the content in some antioxidant molecules. The aim of this manuscript is to provide with data on the potential of PTC powder fractions of \u003cem\u003eD. glomerata\u003c/em\u003e and \u003cem\u003eH. sabdariffa\u003c/em\u003e spices to be used as an alternative and/or complementary strategy in managing oxidative reactions, a risk factor associated to physiological conditions, and in several pathological conditions.\u003c/p\u003e"},{"header":"Materials and methods","content":"\u003cdiv id=\"Sec3\" class=\"Section2\"\u003e \u003ch2\u003eChemicals\u003c/h2\u003e \u003cp\u003eFolin-Ciocalteu\u0026rsquo;s reagent and ethanol has been supplied by WWR International, Fontenay-sous-Bois, France, while potassium ferricyanide (K\u003csub\u003e3\u003c/sub\u003eFe(CN)\u003csub\u003e6\u003c/sub\u003e), potassium ferrocynanide (K\u003csub\u003e4\u003c/sub\u003eFe(CN)\u003csub\u003e6\u003c/sub\u003e), 6-hydroxy-2,5,7,8-tetramethylchlorman-2-carboxylic acid (Trolox), ascorbic acid, α-tocopherol, butylated hydroxytoluene (BHT), butylated hydroxyanisole (BHA) were purchased from Steinheim in Germany supplied by Sigma-Aldrich GmbH.\u003c/p\u003e \u003c/div\u003e\n\u003ch3\u003ePlant material\u003c/h3\u003e\n\u003cp\u003eSamples were bought from vendors in different localities: dried red calyces of \u003cem\u003eH. sabdariffa\u003c/em\u003e were purchased from local market in the Adamaoua region, while dried fruits of \u003cem\u003eD. glomerata\u003c/em\u003e were bought in a market located in Yaound\u0026eacute;, central region of Cameroon. Plant materials used in this study complied with national guidelines. Each plant material was manually separated from inorganic materials, dirt, and dust particles.\u003c/p\u003e\n\u003ch3\u003ePlant material pulverization\u003c/h3\u003e\n\u003cp\u003eAn electric ultra-centrifugal mill ZM 200 (Retsch, Haan, Germany) characterized with a sieve with 24-tooth rotor of 99 mm diameter and sieve with 1 mm trapezoid holes; was used to pulverize dry plant parts by impact and also the shearing size reduction principles. Dried fruits of \u003cem\u003eD. glomerata\u003c/em\u003e and dried calyces of \u003cem\u003eH. sabdariffa\u003c/em\u003e (50 g per batch) were pulverized at a rotor speed of 6,200 \u003cem\u003eg\u003c/em\u003e at ambient temperature of about 20\u0026deg;C. This rotor speed was explained to be a compromise between grinding efficiency and local temperature increase in plant parts during grinding, as the latter is known to be activated at high rotor speed and lead to an alteration in bioactive compounds [\u003cspan citationid=\"CR8\" class=\"CitationRef\"\u003e8\u003c/span\u003e].\u003c/p\u003e\n\u003ch3\u003eProduction of PTC powder fractions\u003c/h3\u003e\n\u003cp\u003eThe control sieving operation of PTC technology was used for powder fractions production. In this respect, each plant powder was fractionated into four particle size using an Analysette 3 Spartan sieve shaker (Fritsch, Idar-Oberstein, Germany) with 180, 212, 315 \u0026micro;m standard sieve sizes. Powder (100 g) was gently transferred on the first uppermost sieve and the whole set up operating by vertical vibration at 0.5 mm vibration amplitude in permanent mode for 10 min. Then after, the powder retained on each sieve was retrieved and weighed. The following powder fractions used were produced using particle sizes: \u0026lt; 180 \u0026micro;m, 180\u0026ndash;212 \u0026micro;m, 212\u0026ndash;315 \u0026micro;m and \u0026ge;\u0026thinsp;315 \u0026micro;m. The control sample was the unsieved powder of each plant. Antioxidant analysis by using PAOT-liquid and FRAP methods were conducted on powder fractions.\u003c/p\u003e \u003cp\u003e.\u003c/p\u003e\n\u003ch3\u003eFerric Reducing Antioxidant Power assay\u003c/h3\u003e\n\u003cp\u003eFRAP assay was carried out according to Oyaizu [\u003cspan citationid=\"CR12\" class=\"CitationRef\"\u003e12\u003c/span\u003e]. This assay measures the antioxidant capacity in samples which is based on the reduction of ferric iron (Fe\u003csup\u003e3+\u003c/sup\u003e) to ferrous iron (Fe\u003csup\u003e2+\u003c/sup\u003e) by the presence of antioxidants in the samples. 1 mL of each powder extract or ascorbic acid solutions (at 0.02, 0.04, 0.06, 0.08 and 0.1 mg/mL) was mixed with 2.5 mL of phosphate buffer (0.2 mol/L, pH 6.6) and with equal portion, 2.5 mL, of potassium ferricyanide [0.03 mol/L, K\u003csub\u003e3\u003c/sub\u003eFe(CN)\u003csub\u003e6\u003c/sub\u003e]. Then, the mixture was incubated at 50\u0026deg;C for 20 min. 2.5 mL of 0.6 mol/L trichloroacetic acid were later on added to the mixture, followed by centrifugation for 10 min at 821 g. The supernatant of solution (2.5 mL) was mixed with 2.5 mL of distilled water and 0.5 mL of 0.1 mol/L FeCl\u003csub\u003e3\u003c/sub\u003e, and using a spectrophotometer (Shimadzu UV-VIS 1605, Tokyo, Japan), the absorbance was measured at a wavelength of 700 nm. Ferric reducing antioxidant power (FRAP) was expressed as ascorbic acid equivalent (AAE) per gram of dry sample.\u003c/p\u003e \u003cdiv id=\"Sec8\" class=\"Section2\"\u003e \u003ch2\u003e\u003cb\u003eMeasurement of antioxidant activity by PAOT\u0026ndash;liquid assay\u003c/b\u003e\u003c/h2\u003e \u003cp\u003ePAOT-Liquid is a method of determining the antioxidant capacity of various matrices such as raw materials and processed food products, cosmetic and medicinal preparations, biological fluids, or plant extracts [\u003cspan citationid=\"CR13\" class=\"CitationRef\"\u003e13\u003c/span\u003e, \u003cspan citationid=\"CR11\" class=\"CitationRef\"\u003e11\u003c/span\u003e]. The PAOT-Liquid technique is actually the subject of a patent application filing (patent FR1871986; 11.28.2018). The principle is based on the measurement of electric potential variation resulting from chemical reactions between antioxidants and a free radical mediator (M\u003csup\u003e●\u003c/sup\u003e) as source of oxidants. This change results from the variation in the concentrations of the oxidized/reduced forms during reaction (Eq.\u0026nbsp;1) for antioxidants and reaction (Eq.\u0026nbsp;2) for oxidants:\u003c/p\u003e \u003cp\u003e \u003cem\u003eReaction medium\u0026thinsp;+\u0026thinsp;AO (Antioxidant) --------\u0026gt; Reaction medium\u0026thinsp;+\u0026thinsp;AOOx (Result of the antioxidant oxidation) (Eq.\u0026nbsp;1)\u003c/em\u003e \u003c/p\u003e \u003cp\u003e \u003cem\u003eReaction medium\u0026thinsp;+\u0026thinsp;OA (Oxidant) -------\u0026gt; Reaction medium\u0026thinsp;+\u0026thinsp;OARed (Result of the oxidant reduction) (Eq.\u0026nbsp;2)\u003c/em\u003e \u003c/p\u003e \u003cp\u003eThe measurement is done in a liquid medium by solubilization of sample extract in a reaction medium and then its activity is assayed directly in solution. The measurement was carried out in a reaction medium (1 mL physiological solution at pH ranging from 6.7\u0026ndash;7.2 to simulate biological conditions during analysis), containing a molecule in a free radical state called mediator (M\u0026bull;). Two specific microelectrodes, one being the working electrode and the second one the reference electrode, were immersed in sample solution for a few minutes at 24\u0026ndash;27\u0026deg;C. After addition of 20 \u0026micro;L of pure antioxidants or plant powder extracts, PAOT-liquid activity was estimated by registering electrochemical potential modifications in the reaction medium (due to variation in the concentrations of the oxidized/reduced forms during the oxidation of antioxidants and the reduction of oxidants). Antioxidant activity was calculated according to the following formula:\u003c/p\u003e \u003cp\u003e \u003cspan class=\"InlineEquation\"\u003e \u003cspan class=\"mathinline\"\u003e\\(\\:\\text{A}\\text{n}\\text{t}\\text{i}\\text{o}\\text{x}\\text{y}\\text{d}\\text{a}\\text{n}\\text{t}\\:\\text{a}\\text{c}\\text{t}\\text{i}\\text{v}\\text{i}\\text{t}\\text{y}=\\left(\\frac{\\text{E}\\text{P}\\:\\text{p}\\text{r}\\text{o}\\text{d}\\text{u}\\text{c}\\text{t}\\:\\:-\\:\\text{E}\\text{P}\\:\\text{c}\\text{o}\\text{n}\\text{t}\\text{r}\\text{o}\\text{l}\\:}{\\text{E}\\text{P}\\:\\text{c}\\text{o}\\text{n}\\text{t}\\text{r}\\text{o}\\text{l}\\:}\\right)\\times\\:\\:100\\%\\:\\)\u003c/span\u003e \u003c/span\u003e (Eq.\u0026nbsp;3)\u003c/p\u003e \u003cp\u003eWhere \u003cem\u003eEP control\u003c/em\u003e is the electrochemical potential at time 0 and \u003cem\u003eEP product\u003c/em\u003e is the electrochemical potential obtained after 10 min registration of tested antioxidants or powder samples. Pure antioxidants were equally tested as references and results expressed on their basis: trolox, ascorbic acid, α-tocopherol, BHT and BHA.\u003c/p\u003e \u003c/div\u003e\n\u003ch3\u003eStatistical tools used in the analysis of data\u003c/h3\u003e\n\u003cp\u003eResults were expressed as mean\u0026thinsp;\u0026plusmn;\u0026thinsp;standard deviation of at least three determinations (n\u0026thinsp;=\u0026thinsp;3). Data were subjected to analysis of variance (ANOVA) to determine if there were statistically significant (\u003cem\u003ep\u003c/em\u003e\u0026thinsp;\u0026lt;\u0026thinsp;0.05) differences among the powder fractions. Duncan multiple range test was used to determine the difference between two subsequent samples. Correlations and multilinear regression analysis between antioxidant activity of plant powders and bioactive molecules, including PAOT-liquid technology, FRAP, total phenols, flavonoid, zinc, copper and vit C contents reported in earlier publications (8, 9) was conducted using the regression program in Statgraphics centurion version 15.1. For regression models, the antioxidant activity was calculated as a function of bioactive molecules contents. Thus, the contribution of bioactive molecule contents was determined.\u003c/p\u003e"},{"header":"Results and discussion","content":"\u003cdiv id=\"Sec11\" class=\"Section2\"\u003e \u003ch2\u003eFerric reducing antioxidant power\u003c/h2\u003e \u003cp\u003eThe FRAP assay measures the antioxidant effect of any substance in the reaction medium as reducing ability. As shown in Table\u0026nbsp;\u003cspan refid=\"Tab1\" class=\"InternalRef\"\u003e1\u003c/span\u003e, the ferric reducing antioxidant power varied significantly (\u003cem\u003ep\u003c/em\u003e\u0026thinsp;\u0026lt;\u0026thinsp;0.05) with plant species, although values of both \u003cem\u003eD. glomerata\u003c/em\u003e and \u003cem\u003eH. sabdariffa\u003c/em\u003e could be considered high. Meanwhile, the FRAP activity was higher (60.03\u0026thinsp;\u0026plusmn;\u0026thinsp;0.75 mg AAE/g DW) for the unsieved \u003cem\u003eD. glomerata\u003c/em\u003e powder than for unsieved \u003cem\u003eH. sabdariffa\u003c/em\u003e powder (38.96\u0026thinsp;\u0026plusmn;\u0026thinsp;0.57 mg AAE/g DW). Looking to the powder fractions, a significant difference (\u003cem\u003ep\u003c/em\u003e\u0026thinsp;\u0026lt;\u0026thinsp;0.05) were denoted between the different fractions of the same plant. FRAP assay revealed the highest antioxidant activity for the 180\u0026ndash;212 \u0026micro;m fraction of \u003cem\u003eD. glomerata\u003c/em\u003e powder and the fraction 212\u0026ndash;315 \u0026micro;m size class for \u003cem\u003eH. sabdariffa\u003c/em\u003e. Results in literature reported that the antioxidant activity of \u003cem\u003eD. glomerata\u003c/em\u003e was particularly high as compared to many plants such as \u003cem\u003eFagara leprieuri\u003c/em\u003e, \u003cem\u003eScorodophleus zenkeri\u003c/em\u003e (fruit), \u003cem\u003eTetrapleura tetraptera\u003c/em\u003e and \u003cem\u003eHua gabonii\u003c/em\u003e (fruit) [\u003cspan citationid=\"CR14\" class=\"CitationRef\"\u003e14\u003c/span\u003e, \u003cspan citationid=\"CR15\" class=\"CitationRef\"\u003e15\u003c/span\u003e], thus supporting the antioxidative potential of this plant. In addition, literature also revealed the potential of sieved fractionation on the improvement of antioxidant properties of food powders. In particular, the fraction with the highest activity found in this study had previously been found to be richer in antioxidant compounds, especially in phenolic compounds, DPPH and ABTS antiradical properties. Globally results indicated an improvement in antioxidant capacity of both plant powders with PTC technology.\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\u003eFRAP antioxidant activity (mg AAE/g DW) of powder fractions and unsieved powder of \u003cem\u003eD. glomerata\u003c/em\u003e fruits and \u003cem\u003eH. sabdariffa\u003c/em\u003e calyces\u003c/p\u003e \u003c/div\u003e \u003c/caption\u003e \u003ccolgroup cols=\"3\"\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c1\" colnum=\"1\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c2\" colnum=\"2\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c3\" colnum=\"3\"\u003e\u003c/div\u003e \u003cthead\u003e \u003ctr\u003e \u003cth align=\"left\" colname=\"c1\"\u003e \u003cp\u003ePowder fractions\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c2\"\u003e \u003cp\u003e\u003cem\u003eD. glomerata\u003c/em\u003e\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c3\"\u003e \u003cp\u003e\u003cem\u003eH. sabdariffa\u003c/em\u003e\u003c/p\u003e \u003c/th\u003e \u003c/tr\u003e \u003c/thead\u003e \u003ctbody\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u0026lt;\u0026thinsp;180 \u0026micro;m\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e59.96\u0026thinsp;\u0026plusmn;\u0026thinsp;2.70\u003csup\u003ec\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e39.46\u0026thinsp;\u0026plusmn;\u0026thinsp;0.65\u003csup\u003eb\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e180\u0026ndash;212 \u0026micro;m\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e63.43\u0026thinsp;\u0026plusmn;\u0026thinsp;0.20\u003csup\u003ed\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e38.67\u0026thinsp;\u0026plusmn;\u0026thinsp;0.13\u003csup\u003eb\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e212\u0026ndash;315 \u0026micro;m\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e53.91\u0026thinsp;\u0026plusmn;\u0026thinsp;0.90\u003csup\u003eb\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e40.99\u0026thinsp;\u0026plusmn;\u0026thinsp;0.53\u003csup\u003ec\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u0026ge;\u0026thinsp;315 \u0026micro;m\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e40.62\u0026thinsp;\u0026plusmn;\u0026thinsp;2.08\u003csup\u003ea\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e33.83\u0026thinsp;\u0026plusmn;\u0026thinsp;0.96\u003csup\u003ea\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eUnsieved\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e60.03\u0026thinsp;\u0026plusmn;\u0026thinsp;0.75\u003csup\u003ec\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e38.96\u0026thinsp;\u0026plusmn;\u0026thinsp;0.57\u003csup\u003eb\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003c/tbody\u003e \u003c/colgroup\u003e \u003ctfoot\u003e \u003ctr\u003e\u003ctd colspan=\"3\"\u003e\u003cem\u003eFor each plant, means\u0026thinsp;\u0026plusmn;\u0026thinsp;standard deviations (n\u0026thinsp;=\u0026thinsp;3) followed by the same superscripted letter were not significantly different (p\u003c/em\u003e\u0026thinsp;\u0026lt;\u0026thinsp;0.05\u003cem\u003e)\u003c/em\u003e\u003c/td\u003e\u003c/tr\u003e \u003c/tfoot\u003e \u003c/table\u003e\u003c/div\u003e \u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec12\" class=\"Section2\"\u003e \u003ch2\u003eTotal antioxidant power (PAOT)\u003c/h2\u003e \u003cp\u003eThe PAOT of \u003cem\u003eD. glomerata\u003c/em\u003e and \u003cem\u003eH. sabdariffa\u003c/em\u003e powders, expressed in mg equivalent of antioxidant references per gram of dry sample, is shown in Fig.\u0026nbsp;\u003cspan refid=\"Fig1\" class=\"InternalRef\"\u003e1\u003c/span\u003e (A and B). The plant powders with highest PAOT antioxidant capacity was found to be \u003cem\u003eD. glomerata\u003c/em\u003e compared to \u003cem\u003eH. sabdariffa\u003c/em\u003e, irrespective of the fraction. PAOT of unsieved powder from \u003cem\u003eD. glomerata\u003c/em\u003e fruits was 45.95 mg trolox equivalents/g DW, while PAOT expressed on the basis of ascorbic acid, BHA, BHT and α-tocopherol equivalent were 27.3, 70.7, 72.0 and 48.9 mg/g DW, respectively. For \u003cem\u003eH. sabdariffa\u003c/em\u003e calyces, the PAOT were 30.5, 18.1, 47.0, 47.8 and 32.5 mg of trolox, ascorbic acid, BHA, BHT and α-tocopherol, respectively. It clearly appeared from these data that the fractions with high PAOT activity were 180\u0026ndash;212 \u0026micro;m and 212\u0026ndash;315\u0026micro;m for \u003cem\u003eD. glomerata\u003c/em\u003e and \u003cem\u003eH. sabdariffa\u003c/em\u003e, respectively. Similar antioxidant profile is reported above for FRAP, suggesting the pertinence of the PAOT technology.\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003cp\u003eConsidering the increasing need to find effective natural antioxidants agents and the role of diet in reducing oxidant stress, \u003cem\u003eD. glomerata\u003c/em\u003e and \u003cem\u003eH. sabdariffa\u003c/em\u003e powders are markedly to being considered as sources of antioxidant agents. Then, considering PTC fractions from \u003cem\u003eD. glomerata\u003c/em\u003e fruits and \u003cem\u003eH. sabdariffa\u003c/em\u003e calyces to be used as inexpensive medicinal antioxidants such as vitamin C (ascorbic acid) and vitamin E, and according to daily recommended dietary allowance, it appeared that the daily need of vit C or vit E may be covered by these powders. The equivalent quantities of both plant fractions required to fill the daily needs of vitamin C (vitamin C daily need is 90 mg and 75 mg/day for male and female adults, respectively) and α-tocopherol (α-tocopherol daily recommended dietary allowance is 10 mg and 8 mg for male and female adults, respectively) [\u003cspan citationid=\"CR16\" class=\"CitationRef\"\u003e16\u003c/span\u003e] are shown in Table\u0026nbsp;\u003cspan refid=\"Tab2\" class=\"InternalRef\"\u003e2\u003c/span\u003e. In this respect, approximately 2.4 to 4.5 g of \u003cem\u003eD. glomerata\u003c/em\u003e powder and 4.3 to 5.1 g \u003cem\u003eH. sabdariffa\u003c/em\u003e powder are necessary to fill the daily needs of vitamin C in male adults. Similarly, for α-tocopherol, 0.16 to 0.28 g \u003cem\u003eD. glomerata\u003c/em\u003e and 0.28 to 0.33 g of \u003cem\u003eH. sabdariffa\u003c/em\u003e powders are needed. Thus, PTC powder fractions of these two spices can potentially be offered in teas, foods and/or dietary supplements. Looking to the powder fractions from \u003cem\u003eD. glomerata\u003c/em\u003e and \u003cem\u003eH. sabdariffa\u003c/em\u003e separately, significant differences (\u003cem\u003ep\u003c/em\u003e\u0026thinsp;\u0026lt;\u0026thinsp;0.05) were denoted between the different fractions and unsieved powder on the quantity necessary to fill the daily needs of vitamin C and that of α-tocopherol. The minimal powder quantity was found in the fractions 180\u0026ndash;212 \u0026micro;m and 212\u0026ndash;315 \u0026micro;m for \u003cem\u003eD. glomerata\u003c/em\u003e and \u003cem\u003eH. sabdariffa, r\u003c/em\u003eespectively. Indeed, these intermediate size class possessed the highest total antioxidant potential. Powder fraction 180\u0026ndash;212 \u0026micro;m of \u003cem\u003eD. glomerata\u003c/em\u003e exhibited a PAOT antioxidant power of 36.6 mg AAE/g DW. The equivalent PAOT antioxidant power for the other standards compounds were 94.85 mg BHA equivalent/g DW, 96.53 mg BHT equivalent/g DW, 65.56 mg α-tocopherol equivalent/g DW and 61.61 mg trolox equivalent/g DW. As regards \u003cem\u003eH. sabdariffa\u003c/em\u003e powder, 212\u0026ndash;315 \u0026micro;m fraction showed the highest PAOT antioxidant activity of 34.49 mg trolox equivalent/g DW. According to our previous results [\u003cspan citationid=\"CR8\" class=\"CitationRef\"\u003e8\u003c/span\u003e], the intermediate 212\u0026ndash;315 \u0026micro;m fraction of \u003cem\u003eH. sabdariffa\u003c/em\u003e and 180\u0026ndash;212 \u0026micro;m fraction of \u003cem\u003eD. glomerata\u003c/em\u003e had been found to be rich in antioxidant compounds, especially in phenolic compounds and consequently had the highest antioxidant properties, as measured by DPPH and ABTS methods. It also suggests that antioxidative molecules including phenols, flavonoids, tannins, minerals and vitamin C functioned in synergy to confer to the powder their antioxidant properties. This is consistent with the fact that antioxidant capacity of plant products is generally attributed to radical scavenging activity of phenolic compounds. In fact, it was reported in our previous study [\u003cspan citationid=\"CR8\" class=\"CitationRef\"\u003e8\u003c/span\u003e], that phenolic compounds significantly contributed to the DPPH and ABTS radicals scavenging activities of investigated plant powders. However, the phenolic components are not the only contributor of antioxidant capacity; vitamin C and mineral elements were equally reported in relatively high quantity in finer powder fractions (\u0026lt;\u0026thinsp;180 \u0026micro;m and 180\u0026ndash;212 \u0026micro;m) of \u003cem\u003eD. glomerata.\u003c/em\u003e\u003c/p\u003e \u003cp\u003e \u003cdiv class=\"gridtable\"\u003e\u003ctable float=\"Yes\" id=\"Tab2\" border=\"1\"\u003e \u003ccaption language=\"En\"\u003e \u003cdiv class=\"CaptionNumber\"\u003eTable 2\u003c/div\u003e \u003cdiv class=\"CaptionContent\"\u003e \u003cp\u003eEquivalent quantity of powders from \u003cem\u003eD. glomerata\u003c/em\u003e and \u003cem\u003eH. sabdariffa\u003c/em\u003e required to fill the daily needs of vitamin C and α-tocopherol for healthy individuals (\u0026ge;\u0026thinsp;19 years of age) male and female.\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=\"char\" char=\".\" class=\"colspec\" colname=\"c2\" colnum=\"2\"\u003e\u003c/div\u003e \u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c3\" colnum=\"3\"\u003e\u003c/div\u003e \u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c4\" colnum=\"4\"\u003e\u003c/div\u003e \u003cdiv align=\"char\" char=\".\" 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\u003ePowder fractions\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colspan=\"2\" nameend=\"c3\" namest=\"c2\"\u003e \u003cp\u003e\u003cem\u003eD. glomerata\u003c/em\u003e\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colspan=\"2\" nameend=\"c5\" namest=\"c4\"\u003e \u003cp\u003e\u003cem\u003eH. sabdariffa\u003c/em\u003e\u003c/p\u003e \u003c/th\u003e \u003c/tr\u003e \u003ctr\u003e \u003cth align=\"left\" colname=\"c2\"\u003e \u003cp\u003eAscorbic acid (g)\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c3\"\u003e \u003cp\u003eα-tocopherol (g)\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c4\"\u003e \u003cp\u003eAscorbic acid (g)\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c5\"\u003e \u003cp\u003eα-tocopherol (g)\u003c/p\u003e \u003c/th\u003e \u003c/tr\u003e \u003c/thead\u003e \u003ctbody\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u0026lt;\u0026thinsp;180 \u0026micro;m\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e2.7\u0026ndash;2.2\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e0.17\u0026ndash;0.14\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e4.7\u0026ndash;3.9\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e0.30\u0026ndash;0.24\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e180\u0026ndash;212 \u0026micro;m\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e2.4\u0026ndash;2.0\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e0.16\u0026ndash;0.13\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e4.7 \u0026minus;\u0026thinsp;3.9\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e0.30\u0026ndash;0.24\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e212\u0026ndash;315 \u0026micro;m\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e3.2\u0026ndash;2.7\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e0.21\u0026ndash;0.17\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e4.3\u0026ndash;3.7\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e0.28\u0026ndash;0.22\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u0026ge;\u0026thinsp;315 \u0026micro;m\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e4.5\u0026ndash;3.8\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e0.28\u0026ndash;0.23\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e5.1\u0026ndash;4.3\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e0.33\u0026ndash;0.26\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eUnsieved\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e3.2\u0026ndash;2.7\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e0.21\u0026ndash;0.17\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e5.0\u0026ndash;4.1\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e0.31\u0026ndash;0.25\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003c/tbody\u003e \u003c/colgroup\u003e \u003c/table\u003e\u003c/div\u003e \u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec13\" class=\"Section2\"\u003e \u003ch2\u003eRelationship between bioactive substances and antioxidant properties\u003c/h2\u003e \u003cp\u003eIn order to evaluate the suitability and reliability of the essay methods used to determine the total antioxidant potential of \u003cem\u003eD. glomerata\u003c/em\u003e and \u003cem\u003eH. sabdariffa\u003c/em\u003e powders, we performed Pearson\u0026rsquo;s correlation on the values of bioactive molecules and antioxidant constituents reported in our previous studies [\u003cspan citationid=\"CR8\" class=\"CitationRef\"\u003e8\u003c/span\u003e, \u003cspan citationid=\"CR9\" class=\"CitationRef\"\u003e9\u003c/span\u003e] and under investigation. The analysis is based on link between the antioxidant compounds (phenolic, Zn, Cu, total carotenoids and vit C contents) and the antioxidant capacity of the plant powders (PAOT, FRAP, DPPH and ABTS assays). As shown in Table\u0026nbsp;\u003cspan refid=\"Tab3\" class=\"InternalRef\"\u003e3\u003c/span\u003e, FRAP and PAOT were significantly and negatively correlated with DPPH and ABTS. The DPPH and ABTS were expressed as concentration of powder that inhibited 50% of the radical. Then negative correlation with DPPH and ABTS were expected and indicated that all antioxidant tests were intercorrelated. The DPPH was strongly correlated with ABTS (r\u0026thinsp;=\u0026thinsp;0.82, \u003cem\u003ep\u003c/em\u003e\u0026thinsp;\u0026lt;\u0026thinsp;0.05). PAOT and FRAP were all strongly correlated with total phenolics (r\u0026thinsp;=\u0026thinsp;0.95 and r\u0026thinsp;=\u0026thinsp;0.97, \u003cem\u003ep\u003c/em\u003e\u0026thinsp;\u0026lt;\u0026thinsp;0.05), while DPPH and ABTS were negatively correlated with total phenolics (r = -0.86, r = -0.91, respectively). The strong correlation between the total antioxidant capacity assayed by DPPH, ABTS, FRAP and PAOT-liquid methods and total phenolics indicated that the phenolic compounds could play an important role in antioxidant property of these plant powders. Moreover, the correlation between vit C versus PAOT-liquid, FRAP, DPPH and ABTS were also significant and higher (r\u0026thinsp;=\u0026thinsp;0.91, r\u0026thinsp;=\u0026thinsp;0.83, r = -0.79, r = -0.87, respectively), suggesting that the antioxidant activity of \u003cem\u003eD. glomerata\u003c/em\u003e and \u003cem\u003eH. sabdariffa\u003c/em\u003e powders were equally dependent on the vit C. Minerals were also found to contribute to the antioxidant property of the powders either negatively or positively. In fact, while powder fractions with high copper content exhibited high antioxidant activities (r\u0026thinsp;\u0026gt;\u0026thinsp;0.73), inverse observations were made for zinc. This observation is probably a result of the negative correlation, although non-significant, between the concentration of Zn\u003csup\u003e2+\u003c/sup\u003e and Cu\u003csup\u003e2+\u003c/sup\u003e in the plant powders (r = -0.33). In addition, literature reported that while nonenzymatic antioxidants such as α-tocopherol, vit C and phenolics can prevent or slow oxidation by interacting directly with radicals or carbon-centered free radicals, zinc is known as non-redox active and its antioxidant role is mostly seen \u003cem\u003ein vivo\u003c/em\u003e as cofactors of superoxide dismutase [\u003cspan citationid=\"CR17\" class=\"CitationRef\"\u003e17\u003c/span\u003e]. Owing to the similarities in their coordination chemistry, it is also reported that Zn\u003csup\u003e2+\u003c/sup\u003e can compete with Cu\u003csup\u003e2+\u003c/sup\u003e for certain types of binding sites, and thereby suppress their ability to transfer electron in a particular environment [\u003cspan citationid=\"CR17\" class=\"CitationRef\"\u003e17\u003c/span\u003e]. These correlations contrasted with the theory behind both minerals, as Cu\u003csup\u003e2+\u003c/sup\u003e is generally thought of as a prooxidant that causes free radical damage and lipid peroxidation. Whatever the case, the present result pointed out the opposed role of both minerals in the \u003cem\u003ein vitro\u003c/em\u003e antioxidant capacity of powder, one being antioxidant the other being prooxidant. The role of phenolic compounds and vit C as antioxidant of plant origin including herbs and medicinal plants is well documented [\u003cspan citationid=\"CR18\" class=\"CitationRef\"\u003e18\u003c/span\u003e, \u003cspan citationid=\"CR19\" class=\"CitationRef\"\u003e19\u003c/span\u003e].\u003c/p\u003e \u003cp\u003e \u003cdiv class=\"gridtable\"\u003e\u003ctable float=\"Yes\" id=\"Tab3\" border=\"1\"\u003e \u003ccaption language=\"En\"\u003e \u003cdiv class=\"CaptionNumber\"\u003eTable 3\u003c/div\u003e \u003cdiv class=\"CaptionContent\"\u003e \u003cp\u003ePearson\u0026rsquo;s correlation coefficients between the four assays (PAOT, FRAP, DPPH and ABTS) and between the assays and antioxidant constituents (total phenols, flavonoids, vit C, total carotenoids, zinc and copper)\u003c/p\u003e \u003c/div\u003e \u003c/caption\u003e \u003ccolgroup cols=\"11\"\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 \u003cdiv align=\"left\" class=\"colspec\" colname=\"c6\" colnum=\"6\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c7\" colnum=\"7\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c8\" colnum=\"8\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c9\" colnum=\"9\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c10\" colnum=\"10\"\u003e\u003c/div\u003e \u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c11\" colnum=\"11\"\u003e\u003c/div\u003e \u003cthead\u003e \u003ctr\u003e \u003cth align=\"left\" colname=\"c1\"\u003e \u003cp\u003eVariables\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c2\"\u003e \u003cp\u003eTP\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c3\"\u003e \u003cp\u003eFL\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c4\"\u003e \u003cp\u003eZinc\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c5\"\u003e \u003cp\u003eCopper\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c6\"\u003e \u003cp\u003eVit C\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c7\"\u003e \u003cp\u003eTC\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c8\"\u003e \u003cp\u003eDPPH\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c9\"\u003e \u003cp\u003eABTS\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c10\"\u003e \u003cp\u003eFRAP\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c11\"\u003e \u003cp\u003ePAOT\u003c/p\u003e \u003c/th\u003e \u003c/tr\u003e \u003c/thead\u003e \u003ctbody\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eTP\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e\u003cb\u003e1\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c8\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c9\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c10\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c11\"\u003e\u0026nbsp;\u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eFL\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e0.94\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e\u003cb\u003e1\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c8\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c9\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c10\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c11\"\u003e\u0026nbsp;\u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eZinc\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e-0.75\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e-0.77\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e\u003cb\u003e1\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c8\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c9\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c10\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c11\"\u003e\u0026nbsp;\u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eCopper\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e0.74\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e0.81\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e-0.32\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e\u003cb\u003e1\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c8\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c9\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c10\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c11\"\u003e\u0026nbsp;\u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eVit C\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e0.91\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e0.92\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e-0.63\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e0.84\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e\u003cb\u003e1\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c8\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c9\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c10\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c11\"\u003e\u0026nbsp;\u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eTC\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e-0.70\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e-0.73\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e0.91\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e-0.33\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e-0.63\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e \u003cp\u003e\u003cb\u003e1\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c8\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c9\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c10\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c11\"\u003e\u0026nbsp;\u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eDPPH\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e-0.86\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e-0.76\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e0.44\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e-0.83\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e-0.79\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e \u003cp\u003e0.37\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c8\"\u003e \u003cp\u003e\u003cb\u003e1\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c9\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c10\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c11\"\u003e\u0026nbsp;\u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eABTS\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e-0.91\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e-0.91\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e0.63\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e-0.82\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e-0.87\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e \u003cp\u003e0.60\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c8\"\u003e \u003cp\u003e0.82\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c9\"\u003e \u003cp\u003e\u003cb\u003e1\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c10\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c11\"\u003e\u0026nbsp;\u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eFRAP\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e0.95\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e0.92\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e-0.67\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e0.73\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e0.82\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e \u003cp\u003e-0.58\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c8\"\u003e \u003cp\u003e-0.84\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c9\"\u003e \u003cp\u003e-0.90\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c10\"\u003e \u003cp\u003e\u003cb\u003e1\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c11\"\u003e\u0026nbsp;\u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003ePAOT\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e0.97\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e0.91\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e-0.62\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e0.75\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e0.91\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e \u003cp\u003e-0.54\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c8\"\u003e \u003cp\u003e-0.83\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c9\"\u003e \u003cp\u003e-0.90\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c10\"\u003e \u003cp\u003e0.96\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c11\"\u003e \u003cp\u003e\u003cb\u003e1\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003c/tbody\u003e \u003c/colgroup\u003e \u003ctfoot\u003e \u003ctr\u003e\u003ctd colspan=\"11\"\u003e\u003cem\u003eTP: total phenols, FL: flavonoids, TC: total carotenoids\u003c/em\u003e\u003c/td\u003e\u003c/tr\u003e \u003c/tfoot\u003e \u003c/table\u003e\u003c/div\u003e \u003c/p\u003e \u003cp\u003eIn order to analyze the contributions of total phenols, zinc, copper and vit C to the antioxidant activity of \u003cem\u003eD. glomerata\u003c/em\u003e and \u003cem\u003eH. sabdariffa\u003c/em\u003e powders as well as their synergistic effects. Multiple linear regression was employed to construct multiple linear models with antioxidant activity (PAOT-liquid, FRAP, DPPH and ABTS) as the dependent variable (Y) and total phenols, flavonoids, zinc, copper and vit C, as the dependent variables (X). Stepwise elimination of variables (if \u003cem\u003ep\u003c/em\u003e\u0026thinsp;\u0026gt;\u0026thinsp;0.05) and insertion of variables (if \u003cem\u003ep\u003c/em\u003e\u0026thinsp;\u0026lt;\u0026thinsp;0.05) were performed to establish the best fit model that will exactly represent the influence of bioactive molecules on the antioxidant activities of investigated plant powders. As presented in Table\u0026nbsp;\u003cspan refid=\"Tab4\" class=\"InternalRef\"\u003e4\u003c/span\u003e, model 1 was the best fitted model for DPPH, indicating that DPPH was significantly correlated linearly with total phenols, copper, vit C and total carotenoids (R\u0026sup2; = 0.90, \u003cem\u003ep\u003c/em\u003e\u0026thinsp;\u0026lt;\u0026thinsp;0.05), of which 90% of DPPH variation showed dependence on these antioxidant compounds. The fit model 2 for ABTS was also linearly correlated with total phenols, copper, vit C and total carotenoids (R\u0026sup2; = 0.90, \u003cem\u003ep\u003c/em\u003e\u0026thinsp;\u0026lt;\u0026thinsp;0.05) and the 90% variation of ABTS values was attributed to total phenols, copper, vit C and total carotenoids without significant contribution from zinc. Similarly, model 3 showed that FRAP was also significantly linearly correlated with total phenols, copper, vit C and total carotenoids (R\u0026sup2; = 0.94, \u003cem\u003ep\u003c/em\u003e\u0026thinsp;\u0026lt;\u0026thinsp;0.05) and without zinc. Then, total phenols, copper, vit C and total carotenoids may be responsible for the 94% variation of FRAP. Finally, model 4 for PAOT linearly correlated with total phenols, copper, vit C and total carotenoids (R\u0026sup2; = 0.90, \u003cem\u003ep\u003c/em\u003e\u0026thinsp;\u0026lt;\u0026thinsp;0.05) and they explain the 90% variation of PAOT. Based on the current results, the highest antioxidant activity observed in the DPPH, ABTS, FRAP and PAOT assays was due to total phenols, copper, vit C and total carotenoids, suggesting they are the most important bioactive molecules. Moreover, total phenolics seemed to have a higher correlation with antioxidant activity than others molecules. The phenolic compounds are major antioxidants in plant products, and their antioxidant activity have been demonstrated in previous studies [\u003cspan citationid=\"CR20\" class=\"CitationRef\"\u003e20\u003c/span\u003e, \u003cspan citationid=\"CR8\" class=\"CitationRef\"\u003e8\u003c/span\u003e]. Behind phenolic compounds, vit C and carotenoids are antioxidant constituents of natural plant product. Phenolic antioxidants act by chelating metal ions, adsorbing and neutralizing free radicals, quenching singlet and triplet oxygen, or decomposing peroxides, while carotenoids are known to be very efficient physical and chemical quenchers of singlet oxygen (1O\u003csub\u003e2\u003c/sub\u003e), as well as potent scavengers of other reactive oxygen species [\u003cspan citationid=\"CR21\" class=\"CitationRef\"\u003e21\u003c/span\u003e]. In addition, based on its redox potential and its free radical intermediate, vit C is a chemical reducing agent (antioxidant) in many intracellular and extracellular reactions, and has an ability to donate electrons to ROS to make it stable. The results are in accordance with other works presenting phenolic compounds, vit C and carotenoids as major antioxidant constituent plants, and there are directly associated with the antioxidant activity [\u003cspan citationid=\"CR22\" class=\"CitationRef\"\u003e22\u003c/span\u003e, \u003cspan citationid=\"CR23\" class=\"CitationRef\"\u003e23\u003c/span\u003e, \u003cspan citationid=\"CR18\" class=\"CitationRef\"\u003e18\u003c/span\u003e].\u003c/p\u003e \u003cp\u003e \u003cdiv class=\"gridtable\"\u003e\u003ctable float=\"Yes\" id=\"Tab4\" border=\"1\"\u003e \u003ccaption language=\"En\"\u003e \u003cdiv class=\"CaptionNumber\"\u003eTable 4\u003c/div\u003e \u003cdiv class=\"CaptionContent\"\u003e \u003cp\u003eMultiple linear regression models of PAOT, FRAP, DPPH and ABTS with total phenols, flavonoids, vit C, total carotenoids, zinc and copper contents.\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=\"char\" char=\".\" class=\"colspec\" colname=\"c4\" colnum=\"4\"\u003e\u003c/div\u003e \u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c5\" colnum=\"5\"\u003e\u003c/div\u003e \u003cthead\u003e \u003ctr\u003e \u003cth align=\"left\" colname=\"c1\"\u003e \u003cp\u003eDependent variables (\u003cem\u003eY\u003c/em\u003e)\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c2\"\u003e \u003cp\u003eIndependent variables (\u003cem\u003eX\u003c/em\u003e)\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c3\"\u003e \u003cp\u003eModel numbers and regression equations\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c4\"\u003e \u003cp\u003eR\u003csup\u003e2\u003c/sup\u003e\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c5\"\u003e \u003cp\u003eSignificant (\u003cem\u003ep\u003c/em\u003e value)\u003c/p\u003e \u003c/th\u003e \u003c/tr\u003e \u003c/thead\u003e \u003ctbody\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eDPPH\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\" morerows=\"3\" rowspan=\"4\"\u003e \u003cp\u003eTotal phenols (\u003cem\u003eX\u003c/em\u003e\u003csub\u003e\u003cem\u003e1\u003c/em\u003e\u003c/sub\u003e),\u003c/p\u003e \u003cp\u003eZinc (\u003cem\u003eX\u003c/em\u003e\u003csub\u003e\u003cem\u003e2\u003c/em\u003e\u003c/sub\u003e), copper (\u003cem\u003eX\u003c/em\u003e\u003csub\u003e\u003cem\u003e3\u003c/em\u003e\u003c/sub\u003e),\u003c/p\u003e \u003cp\u003eVit C (\u003cem\u003eX\u003c/em\u003e\u003csub\u003e\u003cem\u003e4\u003c/em\u003e\u003c/sub\u003e),\u003c/p\u003e \u003cp\u003eTotal caroteno\u0026iuml;ds (\u003cem\u003eX\u003c/em\u003e\u003csub\u003e\u003cem\u003e5\u003c/em\u003e\u003c/sub\u003e)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e(1) \u003cem\u003eY\u003c/em\u003e\u0026thinsp;=\u0026thinsp;13.586\u0026ndash;0.783\u003cem\u003eX\u003c/em\u003e\u003csub\u003e\u003cem\u003e1\u003c/em\u003e\u003c/sub\u003e \u0026ndash; 54.307\u003cem\u003eX\u003c/em\u003e\u003csub\u003e\u003cem\u003e3\u003c/em\u003e\u003c/sub\u003e\u0026thinsp;+\u0026thinsp;2.171\u003cem\u003eX\u003c/em\u003e\u003csub\u003e\u003cem\u003e4\u003c/em\u003e\u003c/sub\u003e \u0026ndash; 0.063\u003cem\u003eX\u003c/em\u003e\u003csub\u003e\u003cem\u003e5\u003c/em\u003e\u003c/sub\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e0.90\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e0.033\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eABTS\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e(2) \u003cem\u003eY\u003c/em\u003e\u0026thinsp;=\u0026thinsp;83.599\u0026ndash;3.148\u003cem\u003eX\u003c/em\u003e\u003csub\u003e\u003cem\u003e1\u003c/em\u003e\u003c/sub\u003e \u0026ndash; 299.735\u003cem\u003eX\u003c/em\u003e\u003csub\u003e\u003cem\u003e3\u003c/em\u003e\u003c/sub\u003e\u0026thinsp;+\u0026thinsp;7.585\u003cem\u003eX\u003c/em\u003e\u003csub\u003e\u003cem\u003e4\u003c/em\u003e\u003c/sub\u003e\u0026thinsp;+\u0026thinsp;0.146\u003cem\u003eX\u003c/em\u003e\u003csub\u003e\u003cem\u003e5\u003c/em\u003e\u003c/sub\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e0.90\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e0.040\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eFRAP\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e(3) \u003cem\u003eY\u003c/em\u003e\u0026thinsp;=\u0026thinsp;75.746\u0026thinsp;+\u0026thinsp;0.507\u003cem\u003eX\u003c/em\u003e\u003csub\u003e\u003cem\u003e1\u003c/em\u003e\u003c/sub\u003e\u0026thinsp;+\u0026thinsp;15.393\u003cem\u003eX\u003c/em\u003e\u003csub\u003e\u003cem\u003e3\u003c/em\u003e\u003c/sub\u003e \u0026ndash; 1.169\u003cem\u003eX\u003c/em\u003e\u003csub\u003e\u003cem\u003e4\u003c/em\u003e\u003c/sub\u003e\u0026thinsp;+\u0026thinsp;0.029\u003cem\u003eX\u003c/em\u003e\u003csub\u003e\u003cem\u003e5\u003c/em\u003e\u003c/sub\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e0.94\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e0.011\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003ePAOT\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e(4) \u003cem\u003eY\u003c/em\u003e = \u0026minus;\u0026thinsp;25.648\u0026thinsp;+\u0026thinsp;0.428\u003cem\u003eX\u003c/em\u003e\u003csub\u003e\u003cem\u003e1\u003c/em\u003e\u003c/sub\u003e \u0026ndash; 10.141\u003cem\u003eX\u003c/em\u003e\u003csub\u003e\u003cem\u003e3\u003c/em\u003e\u003c/sub\u003e\u0026thinsp;+\u0026thinsp;0.636\u003cem\u003eX\u003c/em\u003e\u003csub\u003e\u003cem\u003e4\u003c/em\u003e\u003c/sub\u003e\u0026thinsp;+\u0026thinsp;0.044\u003cem\u003eX\u003c/em\u003e\u003csub\u003e\u003cem\u003e5\u003c/em\u003e\u003c/sub\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e0.90\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e0.002\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003c/tbody\u003e \u003c/colgroup\u003e \u003c/table\u003e\u003c/div\u003e \u003c/p\u003e \u003cp\u003eAntioxidant molecules such as polyphenols, vit C and carotenoids from \u003cem\u003eD. glomerata\u003c/em\u003e and \u003cem\u003eH. sabdariffa\u003c/em\u003e may not only exert their antioxidant effect by acting directly on scavenging ROS, but also by alternating their effect and inducing the expression of other antioxidant enzymes. Our recent study reported that the individual PTC powder fraction from \u003cem\u003eD. glomerata\u003c/em\u003e at the dose of 250 mg/kg body weight increased levels of superoxide dismutase and catalase activities in rats, and consequently reduce malondialdehyde production in the liver and plasma [\u003cspan citationid=\"CR9\" class=\"CitationRef\"\u003e9\u003c/span\u003e]. \u003cem\u003eD. glomerata\u003c/em\u003e are commonly used as spices and the potential adverse effects of \u003cem\u003eD. glomerata\u003c/em\u003e fruits pod extract at dose levels of 100, 1000 and 2500 mg/kg body weight/day for 90-days, in a sub-chronic toxicity study and in genotoxicity, no-observed-adverse-effect level for \u003cem\u003eD. glomerata\u003c/em\u003e was observed [\u003cspan citationid=\"CR24\" class=\"CitationRef\"\u003e24\u003c/span\u003e]. Anti-Inflammatory activities of \u003cem\u003eD. glomerata\u003c/em\u003e fruits in rats was also reported [\u003cspan citationid=\"CR25\" class=\"CitationRef\"\u003e25\u003c/span\u003e]. Similar important antioxidative and anti-inflammatory activities of \u003cem\u003eH. sabdariffa\u003c/em\u003e have been equally reported in cell, animal and human models [\u003cspan citationid=\"CR26\" class=\"CitationRef\"\u003e26\u003c/span\u003e]. More precisely a consumption of 125 mg/kg/day of \u003cem\u003eH. sabdariffa\u003c/em\u003e polyphenols by human patients for four weeks decreased the majority of the inflammatory and oxidative stress biomarkers analyzed, as well as increased the anti-inflammatory hormone adiponectin [\u003cspan citationid=\"CR27\" class=\"CitationRef\"\u003e27\u003c/span\u003e]. \u003cem\u003eH. sabdariffa\u003c/em\u003e calyces are frequently consumed by populations as drink, and toxicity studies revealed no risks on immune system, liver and kidney functions as well as serum enzymes [\u003cspan citationid=\"CR28\" class=\"CitationRef\"\u003e28\u003c/span\u003e]. All these studies support the hypothesis formulated in the present study, that the investigated powder fractions from \u003cem\u003eD. glomerata\u003c/em\u003e fruits and \u003cem\u003eH. sabdariffa\u003c/em\u003e calyces can prevent and ameliorating oxidative stress in viral infection such in COVID-19.\u003c/p\u003e \u003cp\u003eThe fatality of COVID-19 is mainly due to the severity of the symptoms including coagulopathy, inflammation and immune depression [\u003cspan citationid=\"CR29\" class=\"CitationRef\"\u003e29\u003c/span\u003e]. Although this is still under investigation, there are many evidences that oxidative stress is a probable cause of multi organ failure in the COVID-19 [\u003cspan citationid=\"CR29\" class=\"CitationRef\"\u003e29\u003c/span\u003e]. Studies by Van der Brand et al. [\u003cspan citationid=\"CR30\" class=\"CitationRef\"\u003e30\u003c/span\u003e] reported and favored ROS levels and disturbance of antioxidant defense during SARS-CoV infection in animal models under experimentation of severe acute respiratory syndrome. In addition, Smith et al. [\u003cspan citationid=\"CR31\" class=\"CitationRef\"\u003e31\u003c/span\u003e] reported during the onset of severe lung injury in SARS-CoV infected patients, an activation of oxidative stress machinery, coupled with innate immunity and activated transcription factors, and finally a serious proinflammatory host response. Lin et al. [\u003cspan citationid=\"CR32\" class=\"CitationRef\"\u003e32\u003c/span\u003e] showed that SARS-CoV 3 CLpro (a viral protease) caused a significant increase in ROS production in HL-CZ cells, which in turn, is involved in 3CL pro-induced cell apoptosis.\u003c/p\u003e \u003c/div\u003e"},{"header":"Conclusion","content":"\u003cp\u003eThe present study aims to show the antioxidant potentials of PTC powder fractions from \u003cem\u003eD. glomerata\u003c/em\u003e fruits and \u003cem\u003eH. sabdariffa\u003c/em\u003e calyces, ingredients known as a good source of antioxidant that could be use in the management oxidative reactions. PAOT-liquid technology and FRAP assay were used to measure the antioxidant activity of the powder fractions. Correlation between the antioxidant activities determined by these methods and bioactive molecules in powders was performed. Results show that both \u003cem\u003eD. glomerata\u003c/em\u003e and \u003cem\u003eH. sabdariffa\u003c/em\u003e powders have high antioxidant potential which varies with the powder fraction. The highest antioxidant activity was recorded for the 180\u0026ndash;212 \u0026micro;m and 212\u0026ndash;315 \u0026micro;m powder fractions of \u003cem\u003eD. glomerata\u003c/em\u003e powder and \u003cem\u003eH. sabdariffa\u003c/em\u003e, respectively. The study reinforces the general knowledge that the antioxidant activity of \u003cem\u003eD. glomerata\u003c/em\u003e and \u003cem\u003eH. sabdariffa\u003c/em\u003e powders is attributed to their antioxidant molecules and in particular phenolics, vit C, and copper. The PAOT-liquid activity is highly correlated with these compounds and to the classical FRAP assay which is often used for evaluating antioxidant capacity of food matrices. The daily consumption of 2.0-2.5 g and 3.7\u0026ndash;4.3 g powder fractions 180\u0026ndash;212 \u0026micro;m and 212\u0026ndash;315 \u0026micro;m from \u003cem\u003eD. glomerata\u003c/em\u003e fruits and \u003cem\u003eH. sabdariffa\u003c/em\u003e calyces is sufficient to cover the daily needs of vit C for an adult, useful to manage oxidative reactions associated in Covid-19 disease. These quantities not only have the advantage to cover the daily needs of α-tocopherol, but also contribute to the copper and zinc which interfere with virus invasion.\u003c/p\u003e"},{"header":"Abbreviations","content":"\u003cp\u003ePTC: pulverization and controlled sieving process\u003c/p\u003e\n\u003cp\u003ePAOT: total antioxidant power\u003c/p\u003e\n\u003cp\u003eBHA:\u003c/p\u003e\n\u003cp\u003eBHT:\u003c/p\u003e\n\u003cp\u003eABTS: Azinobis 3-ethylbenzothiazoline-6-sulfonic acid\u003c/p\u003e\n\u003cp\u003eAAE: ascorbic acid equivalent\u0026nbsp;\u003c/p\u003e\n\u003cp\u003eAO: Antioxidant\u003c/p\u003e\n\u003cp\u003eANOVA: analysis of variance\u0026nbsp;\u003c/p\u003e\n\u003cp\u003eBHT:\u0026nbsp;butylated hydroxytoluene\u003c/p\u003e\n\u003cp\u003eBHA:\u0026nbsp;butylated hydroxyanisole\u0026nbsp;\u003c/p\u003e\n\u003cp\u003eDPPH: 2,2-diphenyl-1-picrylhydrazyl\u003c/p\u003e\n\u003cp\u003eDW: dry weight\u003c/p\u003e\n\u003cp\u003eFRAP: ferric reducing antioxidant power\u0026nbsp;\u003c/p\u003e\n\u003cp\u003eORAC: Oxygen Radical Absorbance Capacity\u003c/p\u003e\n\u003cp\u003eTAC: total antioxidative capacity\u0026nbsp;\u003c/p\u003e"},{"header":"Declarations","content":"\u003cp\u003e\u003cstrong\u003eAvailability of data and materials\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThe dataset supporting the conclusions of this article is at the disposal of the corresponding author and remains available when needed\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eConflict interest and \u003cstrong\u003efunding\u003c/strong\u003e\u003c/strong\u003e\u0026nbsp;\u003c/p\u003e\n\u003cp\u003eThe authors declare no potential conflicts of interest.\u0026nbsp;The study was funded by\u0026nbsp;the Region Grand Est (France) and Agence Universitaire de la Francophonie (AUF, Francophone University Association) (project n° S0020ADM10607L), who did not have any role in the different parts of the study\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eEthics and consent\u0026nbsp;\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eNo experience has been performed on patients or animals in this study.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eConsent to Participate declaration:\u0026nbsp;\u003c/strong\u003eNot applicable\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eConsent to Publish declaration:\u0026nbsp;\u003c/strong\u003eNot applicable\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eClinical trial number\u003c/strong\u003e: Not applicable.’\u003c/p\u003e"},{"header":"References","content":"\u003col\u003e\u003cli\u003e\u003cspan\u003eSharifi-Rad, J.; Sharifi-Rad, M.; Salehi, B.; Iriti, M.; Roointan, A.; Mnayer, D.; Soltani-Nejad, A.; Afshari, A. 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Doi:\u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003e10.1111/j.1574-695x.2006.00045\u003c/span\u003e\u003cspan address=\"10.1111/j.1574-695x.2006.00045\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e.\u003c/span\u003e\u003c/li\u003e\u003c/ol\u003e"}],"fulltextSource":"","fullText":"","funders":[],"hasAdminPriorityOnWorkflow":false,"hasManuscriptDocX":true,"hasOptedInToPreprint":true,"hasPassedJournalQc":"","hasAnyPriority":false,"hideJournal":false,"highlight":"","institution":"","isAcceptedByJournal":true,"isAuthorSuppliedPdf":false,"isDeskRejected":"","isHiddenFromSearch":false,"isInQc":false,"isInWorkflow":false,"isPdf":false,"isPdfUpToDate":true,"isWithdrawnOrRetracted":false,"journal":{"display":true,"email":"[email protected]","identity":"discover-food","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":false,"externalIdentity":"discoverfood","sideBox":"Learn more about [Discover Food](https://www.springer.com/44187)","snPcode":"","submissionUrl":"","title":"Discover Food","twitterHandle":"","acdcEnabled":true,"dfaEnabled":true,"editorialSystem":"stoa","reportingPortfolio":"Discover Series","inReviewEnabled":true,"inReviewRevisionsEnabled":true},"keywords":"Dichrostachys glomerata, Hibiscus sabdariffa, PTC powder fractions, antioxidants, oxidative stress","lastPublishedDoi":"10.21203/rs.3.rs-6180798/v1","lastPublishedDoiUrl":"https://doi.org/10.21203/rs.3.rs-6180798/v1","license":{"name":"CC BY 4.0","url":"https://creativecommons.org/licenses/by/4.0/"},"manuscriptAbstract":"\u003cp\u003e\u003cem\u003eDichrostachys glomerata\u003c/em\u003e fruits and \u003cem\u003eHibiscus sabdariffa\u003c/em\u003e calyces can be processing into good functional ingredients with antioxidant properties. The plant powder fractions obtained by pulverization and controlled sieving process (\u0026lt; 180 µm, 180 – 212 µm, 212 – 315 µm and ≥ 315 µm) were examined for antioxidant capacity using total antioxidant power (PAOT) technology and ferric reducing antioxidant power (FRAP). Results show that both \u003cem\u003eD. glomerata\u003c/em\u003e and \u003cem\u003eH. sabdariffa\u003c/em\u003epowders have high antioxidant potential and large variations in the antioxidant activity in analyzed powder fractions. The highest antioxidant activity was recorded for the 180 – 212 µm and 212 – 315 µm powder fractions of \u003cem\u003eD. glomerata\u003c/em\u003eand \u003cem\u003eH. sabdariffa\u003c/em\u003e, respectively. Using multiple regression, it was find that the antioxidant activity of \u003cem\u003eD. glomerata and H. sabdariffa\u003c/em\u003e powders is attributed to polyphenols. Thus, PAOT-Liquid activity was highly correlated with total polyphenols content of all plant powders (r = 0.97, \u003cem\u003ep \u003c/em\u003e\u0026lt; 0.05) and the classical FRAP assay which is often used for evaluating antioxidant capacity of food matrices (r = 0.96, \u003cem\u003ep \u003c/em\u003e\u0026lt; 0.05). The antioxidant potential of \u003cem\u003eD. glomerata\u003c/em\u003e fruits and \u003cem\u003eH. sabdariffa \u003c/em\u003ecalyces powder fractions could be useful in the management of oxidative reactions.\u003c/p\u003e","manuscriptTitle":"PTC powder fractions of Dichrostachys glomerata Forssk. and Hibiscus sabdariffa L., sources of antioxidants with potential management of oxidative stress","msid":"","msnumber":"","nonDraftVersions":[{"code":1,"date":"2025-05-19 17:44:15","doi":"10.21203/rs.3.rs-6180798/v1","editorialEvents":[{"type":"communityComments","content":0},{"type":"decision","content":"Revision requested","date":"2025-05-30T10:45:02+00:00","index":"","fulltext":""},{"type":"editorInvitedReview","content":"","date":"2025-05-30T10:42:55+00:00","index":"hide","fulltext":""},{"type":"editorInvitedReview","content":"","date":"2025-05-30T10:41:09+00:00","index":"hide","fulltext":""},{"type":"editorInvitedReview","content":"","date":"2025-05-27T07:58:20+00:00","index":"hide","fulltext":""},{"type":"editorInvitedReview","content":"","date":"2025-05-27T03:40:30+00:00","index":"hide","fulltext":""},{"type":"editorInvitedReview","content":"","date":"2025-05-23T13:27:34+00:00","index":"hide","fulltext":""},{"type":"editorInvitedReview","content":"","date":"2025-05-23T04:27:35+00:00","index":"hide","fulltext":""},{"type":"editorInvitedReview","content":"","date":"2025-05-22T04:14:12+00:00","index":"hide","fulltext":""},{"type":"editorInvitedReview","content":"","date":"2025-05-20T13:29:47+00:00","index":"hide","fulltext":""},{"type":"reviewerAgreed","content":"246209263744128219698512133045022486624","date":"2025-05-20T12:57:22+00:00","index":"hide","fulltext":""},{"type":"reviewerAgreed","content":"279468862340339409274910384269462563958","date":"2025-05-20T10:30:59+00:00","index":"hide","fulltext":""},{"type":"reviewerAgreed","content":"209771927303518837916309215652291538493","date":"2025-05-18T02:45:34+00:00","index":"hide","fulltext":""},{"type":"reviewerAgreed","content":"158126601175447014017007797468996570570","date":"2025-05-17T17:38:30+00:00","index":"hide","fulltext":""},{"type":"reviewerAgreed","content":"52200213630618493132361853208324335417","date":"2025-05-17T06:11:28+00:00","index":"hide","fulltext":""},{"type":"reviewerAgreed","content":"118469421422887229094956123691741819534","date":"2025-05-17T05:43:09+00:00","index":"hide","fulltext":""},{"type":"reviewerAgreed","content":"9018441724973471616393282137512599004","date":"2025-05-16T18:18:18+00:00","index":"hide","fulltext":""},{"type":"reviewerAgreed","content":"43049511242756037135511447835605931716","date":"2025-05-15T10:13:15+00:00","index":"hide","fulltext":""},{"type":"reviewerAgreed","content":"338448317997082968136313787015067532694","date":"2025-05-15T06:19:32+00:00","index":"hide","fulltext":""},{"type":"reviewersInvited","content":"","date":"2025-05-15T04:54:00+00:00","index":"","fulltext":""},{"type":"editorAssigned","content":"","date":"2025-05-13T10:47:45+00:00","index":"","fulltext":""},{"type":"checksComplete","content":"","date":"2025-05-02T19:33:23+00:00","index":"","fulltext":""},{"type":"submitted","content":"Discover Food","date":"2025-05-02T19:32:14+00:00","index":"","fulltext":""}],"status":"published","journal":{"display":true,"email":"[email protected]","identity":"discover-food","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":false,"externalIdentity":"discoverfood","sideBox":"Learn more about [Discover Food](https://www.springer.com/44187)","snPcode":"","submissionUrl":"","title":"Discover Food","twitterHandle":"","acdcEnabled":true,"dfaEnabled":true,"editorialSystem":"stoa","reportingPortfolio":"Discover Series","inReviewEnabled":true,"inReviewRevisionsEnabled":true}}],"origin":"","ownerIdentity":"d4725753-db2e-4236-a21a-0a0418ebe809","owner":[],"postedDate":"May 19th, 2025","published":true,"recentEditorialEvents":[],"rejectedJournal":[],"revision":"","amendment":"","status":"under-review","subjectAreas":[],"tags":[],"updatedAt":"2025-08-06T09:38:14+00:00","versionOfRecord":[],"versionCreatedAt":"2025-05-19 17:44:15","video":"","vorDoi":"","vorDoiUrl":"","workflowStages":[]},"version":"v1","identity":"rs-6180798","journalConfig":"researchsquare"},"__N_SSP":true},"page":"/article/[identity]/[[...version]]","query":{"redirect":"/article/rs-6180798","identity":"rs-6180798","version":["v1"]},"buildId":"XKTyCvWXoU3ODBz1xrDgd","isFallback":false,"isExperimentalCompile":false,"dynamicIds":[84888],"gssp":true,"scriptLoader":[]}