Reference Antioxidant Research Articles

Computer-aided design of caffeic acid derivatives: free radical scavenging activity and reaction force

ContextAntioxidants are known to play a beneficial role in human health. Caffeic acid has been previously recognized as efficient in this context. However, such a capability can be enhanced through structural modification. Thus, 3829 caffeic acid derivatives were computational designed to that purpose by adding functional groups (-OH, -SH, -OCH3, -COOCH3, -F, -CF3, and -N(CH3)(C2H5)) to its framework. Promising candidates were chosen considering drug-like behavior, toxicity, and synthetic accessibility. The best candidates, dCAF-2, dCAF-16, and dCAF-82, were identified by comparison with reference antioxidants. The thermochemistry and kinetics of their reaction with •OOH are provided. The global rate coefficients were estimated to be 1.76 × 109 M−1 s−1, 3.19 × 109 M−1 s−1, and 1.79 × 109 M−1 s−1 in aqueous solution for dCAF-2, dCAF-16, and dCAF-82, respectively. In lipid medium, their total rate coefficients were estimated to be 3.65 × 103 M−1 s−1, 3.73 × 103 M−1 s−1, and 8.63 × 104 M−1 s−1 for dCAF-2, dCAF-16, and dCAF-82, respectively. These values allow predicting the designed caffeic acid derivatives as excellent antioxidants in both environments. The reaction forces for the main reaction path of the dCAF-2, dCAF-16, and dCAF-82 reactions with •OOH were explored.MethodsThree protocols were used: (i) CADMA-Chem (computer-assisted design of multifunctional antioxidants, based on chemical properties) to quantify ADME (absorption, distribution, metabolism, and excretion) properties, toxicity and synthetic accessibility; (ii) eH-DAMA (electron and hydrogen donating ability map) tool, to identify the derivatives expected to behave as the best antioxidants; (iii) QM-ORSA (quantum mechanics–based test for overall free radical scavenging activity), to calculate the rate constants. Electronic structure calculations were performed with Gaussian 09, at the M05-2X/6–311 + g(d,p) level of theory. Both aqueous and lipid environments were considered using the SMD continuous solvation model. Intrinsic reaction coordinate (IRC) calculations, as implemented in Gaussian 09, were used to obtain the reaction force.

Влияние пирролидиновых производных 2,6-ди-трет-бутилфенола на супероксид- и пероксид водорода-утилизирующую активность спермы сибирского осетра

The effect of (3.5-di-tert-butyl-4-hydroxyphenyl)-pyrrolidine-2-carboxylic acid derivatives on the ability of Siberian sturgeon (Acipenser baerii, Brandt, 1869) sperm to utilize superoxide anion radical (O2–•) generated in a model system of adrenaline oxidation in an alkaline medium, as well as exogenous hydrogen peroxide (H2O2) before and after freezing at liquid nitrogen temperature for 3 days was studied. The study of this activity of phenolic derivatives was carried out in comparison with the reference antioxidant Trolox, a water-soluble analogue of vitamin E. When phenolic derivatives were added at a concentration of 0.1 mM to the basic Stein cryomedium containing 12.5% egg yolk, 12.5% DMSO, 5 mM KCl, 130 mM NaCl, 20 mM NaHCO3 and 5.5 mM glucose, a multidirectional effect of the compounds on the ability of Siberian sturgeon sperm to utilize superoxide anion radical and hydrogen peroxide before and after the freezing-defrosting process was established. The studied compounds increase the H2O2-utilizing activity of reproductive cells, while reducing their superoxide-utilizing activity. Pyrrolidine derivatives of phenol were found to be more effective in stimulating the H2O2-utilizing activity of defrosted sperm of the Siberian sturgeon than Trolox. A decrease in the rate of O2– • and H2O2 utilization by fish sperm was found after cryopreservation in the control and in the presence of (3.5-di-tert-butyl-4-hydroxyphenyl)-pyrrolidine-2-carboxylic acid derivatives. A protective effect of new phenolic derivatives on the enzymatic link of antioxidant protection of Siberian sturgeon sperm during cryopreservation was shown. The obtained results indicate the prospects for further studies of the protective activity of (3.5-di-tert-butyl-4-hydroxyphenyl)-pyrrolidine-2-carboxylic acid derivatives in the process of cryopreservation of reproductive cells of rare, endangered and commercially valuable fish species.

Investigations on the Endemic Species Taraxacum mirabile Wagenitz: HPLC-MS and GC-MS Studies, Evaluation of Antioxidant, Anti-Inflammatory, and Antimicrobial Properties, and Isolation of Several Phenolic Compounds.

In this study, the aim was to investigate the chemical content and in vitro antioxidant, antimicrobial, and anti-inflammatory activities of petroleum ether (PE), dichloromethane (DCM), ethyl acetate (EA), and n-butanol (n-BuOH) fractions obtained from ethanol extracts of the aerial parts and roots of the endemic Taraxacum mirabile Wagenitz. This plant is found in the Aksaray-Eskil region and has not been studied in phytochemical studies before. In this context, the chemical content of the aerial parts and root PE fractions was analyzed by GC-MS analysis in terms of terpenes and steroid substances. The composition of phenolic compounds in the aerial parts and root DCM and EA fractions was determined by HPLC-MS analysis. Apigenin, luteolin, and caffeic acid were isolated from the EA fraction of aerial parts. The total amounts of phenolic substances and the DPPH, ABTS, and FRAP antioxidant activities of PE, DCM, EA, and n-BuOH fractions were investigated, and it was found that the fractions had the ability to scavenge DPPH• and ABTS•+ radicals, as well as to reduce Fe (III) to Fe (II); however, all of the fractions were significantly less effective (p < 0.05) than the reference antioxidant quercetin. Considering that antioxidants can also exert an anti-inflammatory effect, these fractions were evaluated for their ability to inhibit cyclooxygenases (COX-1 and COX-2), the key enzymes of arachidonic acid metabolism that lead to the production of important mediators of inflammation. It was observed that fractions had the ability to inhibit both enzymes, suggesting their possible beneficial effects against inflammation. However, no extract had greater inhibitory activity than the positive control, indomethacin. The antimicrobial activity was determined against different bacterial and fungal strains. It was observed that the aerial parts and root n-BuOH and EA fractions showed weak antibacterial effects. No antifungal activity has been detected against Candida sp.

Continuous fluorescence-based quantitative antioxidant assay using vegetable oil as an oxidizable substrate

Several spectrophotometric assays, such as 1,1-diphenyl-2-picrylhydrazyl (DPPH) and oxygen radical absorbance capacity (ORAC), are commonly used to assess antioxidant activity. However, these methods often lack real-world relevance as they do not inhibit autoxidation in actual food substrates. Although direct measurement of oxygen consumption or peroxide formation during inhibited autoxidation offers certain advantages, it is labor intensive and requires specialized equipment. In this study, we introduce a small-volume inhibited autoxidation approach that utilizes a standard microplate reader and a food-derived oxidizable substrate, specifically stripped sunflower oil (SSO), and styrene-conjugated BODIPY (STY-BODIPY) chromophores that oxidizes with the substrate, enabling straightforward monitoring of the reaction progress without interfering with it. The rate of initiation (Ri) was controlled by using azobis(isobutyronitrile) (AIBN) at 30 °C (Ri = 8.6 ± 0.5 × 10−10 M s−1) to accurately determine the rate constant of antioxidant reaction with peroxyl radicals (kinh). The method was standardized using the synthetic α-tocopherol analogue 2,2,5,7,8-pentamethyl-6-chromanol (PMC) as a reference antioxidant and was successfully applied to evaluate its synergistic interactions with γ-terpinene, quercetin, and caffeic acid. The rate constant for the reaction of peroxyl radicals with STY-BODIPY was determined, kST = 890 ± 52 M−1 s−1. Induction time (τ) of PMC increased in a concentration-dependent manner by the synergistic interactions of PMC/γ-terpinene, PMC/quercetin, and PMC/caffeic acid. The kinh value for PMC in SSO at 30 °C remained constant at 1.5 × 106 M−1 s−1. The validity of this approach was further confirmed using isothermal calorimetry, demonstrating its potential as a reliable and accessible tool for antioxidant testing in food systems.

Synthesis, crystal structures, DFT calculations, and oxygen radical absorbance capacity of 5-arylidene-thiazolidine-2,4‑dione derivatives

A new green methodology has been developed for the synthesis of a series of substituted 5-arylidene-2,4-thiazolidinediones (ATZDs) 3a-q through Knoevenagel condensation, using barium hydroxide as an efficient heterogeneous catalyst. All compounds were characterized by ¹H NMR, ¹³C NMR, and HRMS spectroscopy. Additionally, seven compounds were analyzed by X-ray diffraction (XRD). Furthermore, some selected TZD derivatives were screened for their antioxidant activity using oxygen radical absorbance capacity (ORAC) assays. The results showed that five compounds exhibited excellent antioxidant properties, with ORAC values ranging from 4.73 TE to 6.31 TE, surpassing the reference antioxidants ferulic acid (3.70 TE) and melatonin (2.45 TE). Computational investigations based on the DFT method revealed that these compounds exert their antioxidant activity primarily through the HAT mechanism, preferentially from the OH bond rather than the NH bond. This study highlights the advantages of this methodology, providing products of high purity, with good yields and short reaction times, and proposes 5-arylidene-thiazolidine-2,4‑dione derivatives as promising antioxidants.

Hamamelitannin’s Antioxidant Effect and Its Inhibition Capability on α-Glycosidase, Carbonic Anhydrase, Acetylcholinesterase, and Butyrylcholinesterase Enzymes

Hamamelitannin (2′,5-di-O-galloyl-hamamelose) bears two-gallate moieties in its structure, and is a natural phenolic product in the leaves and the bark of Hamamelis virginiana. The antioxidant capacity of hamamelitannin was evaluated by a range of methods, with the following findings: the ability to reduce potassium ferric cyanide; the scavenging of N,N-dimethyl-p-phenylenediamine dihydrochloride radical (DMPD•+); the scavenging of 2,2′-azinobis-(3-ethylbenzothiazoline-6-sulphonate) radical (ABTS•+); the scavenging of 1,1-diphenyl-2-picrylhydrazyl radical (DPPH•); and the ability to reduce cupric ions (Cu2+). Additionally, reference antioxidants of α-Tocopherol, butylated hydroxyanisole (BHA), Trolox, and butylated hydroxytoluene (BHT) were used for comparison. For DPPH radical scavenging, hamamelitannin had an IC50 value of 19.31 μg/mL, while the IC50 values for BHA, BHT, Trolox, and α-Tocopherol were 10.10, 25.95, 7.05, and 11.31 μg/mL, respectively. The study found that hamamelitannin functioned similarly to BHA, α-tocopherol, and Trolox in terms of DPPH• scavenging, but better than BHT. Additionally, as a polyphenolic secondary metabolite, the hamamelitannin inhibition capability of several metabolic enzymes was demonstrated, including acetylcholinesterase (AChE), butyrylcholinesterase (BChE), carbonic anhydrase I (CA I), carbonic anhydrase II (CA II) and α-glycosidase. The Ki values of hamamelitannin exhibited 7.40, 1.99, 10.18, 18.26, and 25.79 nM toward AChE, BChE, hCA I, hCA II, and α-glycosidase, respectively.

Antioxidant activity evaluation of the combination of oregano (Origanum vulgare) and laurel (Laurus nobilis) essential oil as two natural “chain-breaking” antioxidants by direct measurement of sunflower oil oxidation

Antioxidants are commonly used to reduce oxidative damage in lipids, and essential oils offer natural alternatives with antioxidant properties. This research seeks to determine the antioxidant efficiency of the combination of laurel (laurus nobilis) and oregano (origanum vulgare) essential oils exhibiting a chain-breaking mechanism. To this end, an accelerated oxidation of sunflower vegetable oil was carried out at 60 °C for 28 days, in combination with concentrations of 0.05% w/w (1) and 0.02% w/w (2) of the essential oils. BHT at 0.02% w/w was used as a reference antioxidant. The chemical indicators of oxidation (dienes conjugated, peroxides, anisidine and TOTOX values) and volatiles (2-heptenal Z, 2,4-Decadienal EZ and EE) were determined. While no substantial differences were found between the studied concentrations of the essential oils, a decrease in the protective effect was observed when the concentration of laurel was increased. Interestingly, the antioxidant effect of both oregano and laurel essential oils was observed to be similar to that of BHT. The results suggest that the combination of these essential oils with chain-breaking antioxidant mechanisms might be used as an antioxidant in food.

Design, Synthesis and Biological Evaluation of Novel Capsaicin Analogues Containing Heterocyclic Fatty Acids

AbstractThere is an urgent need to study safe and biocompatible medicinal compounds which necessitates the discovery of new agents from simple natural starting materials. In this study, eight novel capsaicin derivatives have been synthesized by combination of oxadiazole containing fatty acids with vanillyl amide. All the compounds were characterized by spectral analysis and were examined for their cytotoxicity, antimicrobial, antioxidant and anti‐inflammatory properties. The antioxidant activity of the synthesized derivatives was evaluated by 1,1‐diphenyl‐2‐picryl‐hydrazyl (DPPH) and thiobarbituric acid reactive substances (TBARS) assays. All of the synthesized derivatives have exhibited significant antioxidant activity in comparison to butylated hydroxy toluene (BHT) which is used as a reference antioxidant. The novel capsaicin derivatives with nitro (8 e) and methoxy substituents (8 f, 8 g and 8 h) exhibited the most significant antioxidant activity compared with BHT. In cytotoxicity assay against three cell lines, the derivative with bromo substituent showed excellent activity against B16‐melanoma cancer cell line followed by nitro and methoxy analogs which showed promising activity against HepG2‐ hepato and DU145‐prostate cancer cell lines respectively. In addition, all the derivatives exhibited moderate broad spectrum antibacterial, antifungal and anti‐inflammatory activity.

Assessing the Anti-Inflammatory and Antioxidant Activity of Mangiferin in Murine Model for Myocarditis: Perspectives and Challenges.

Myocarditis is a major cause of heart failure and death, particularly in young individuals. Current treatments are mainly symptomatic, but emerging therapies focus on targeting inflammation and fibrosis pathways. Natural bioactive compounds like flavonoids and phenolic acids show promising anti-inflammatory and antioxidant properties. Corticosteroids are frequently employed in the treatment of autoimmune myocarditis and appear to lower mortality rates compared to conventional therapies for heart failure. This study aims to explore the effects of Mangiferin on pro-inflammatory cytokine levels, nitro-oxidative stress markers, histopathological alterations, and cardiac function in experimental myosin-induced autoimmune myocarditis. The effects were compared to Prednisone, used as a reference anti-inflammatory compound, and Trolox, used as a reference antioxidant. The study involved 30 male Wistar-Bratislava rats, which were randomly divided into five groups: a negative control group (C-), a positive control group with induced myocarditis using a porcine myosin solution (C+), three groups with induced myocarditis receiving Mangiferin (M), Prednisone (P), or Trolox (T) as treatment. Cardiac function was evaluated using echocardiography. Biochemical measurements of nitro-oxidative stress and inflammatory markers were conducted. Finally, histopathological changes were assessed. At echocardiography, the evaluation of the untreated myocarditis group showed a trend toward decreased left ventricular ejection fraction (LVEF) but was not statistically significant, while all treated groups showed some improvement in LVEF and left ventricular fraction shortening (LVFS). Significant changes were seen in the Mangiferin group, with lower end-diastolic left ventricular posterior wall (LVPWd) by day 21 compared to the Trolox group (p < 0.001). In the first week of the experiment, levels of interleukins (IL)-1β, IL-6, and tumour necrosis factor (TNF)-α were significantly higher in the myosin group compared to the negative control group (p < 0.001, p < 0.001, p < 0.01), indicating the progression of inflammation in this group. Treatment with Mangiferin, Prednisone, and Trolox caused a significant reduction in IL-1β compared to the positive control group (p < 0.001). Notably, Mangiferin resulted in a superior reduction in IL-1β compared to Prednisone (p < 0.05) and Trolox (p < 0.05). Furthermore, Mangiferin treatment led to a statistically significant increase in total oxidative capacity (TAC) (p < 0.001) and a significant reduction in nitric oxide (NOx) levels (p < 0.001) compared to the negative control group. Furthermore, when compared to the Prednisone-treated group, Mangiferin significantly reduced NOx levels (p < 0.001) and increased TAC levels (p < 0.001). Mangiferin treatment significantly lowered creatine kinase (CK) and aspartate aminotransferase (AST) levels on day 7 (p < 0.001 and p < 0.01, respectively) and reduced CK levels on day 21 (p < 0.01) compared to the untreated group. In the nontreated group, the histological findings at the end of the experiment were consistent with myocarditis. In the group treated with Mangiferin, only one case exhibited mild inflammatory infiltrates, represented by mononucleated leukocytes admixed with few neutrophils, with the severity graded as mild. Statistically significant correlations between the grades (0 vs. 1-2) and the study groups have been highlighted (p < 0.005). This study demonstrated Mangiferin's cardioprotective effects in autoimmune myocarditis, showing reduced oxidative stress and inflammation. Mangiferin appears promising as a treatment for acute myocarditis, but further research is needed to compare its efficacy with other treatments like Trolox and Prednisone.

Mineral Element and Antioxidant Potential of Four Plants Used in Traditional Medecine in Brazzaville-Congo

Background: Plants represent an important natural resource of secondary metabolites with therapeutic properties and nutrients, including minerals, which contribute to the proper functioning and well-being of the human body. Aims: Four medicinal plants used in Congo-Brazzaville were selected in order to determine their mineral element content and assess their antioxidant activity. Methodology: Mineral element content were determined by atomic absorption spectrometry with flame and flameless. The antioxidant activity assessed, using the DPPH radical scavenging test and iron reducing capacity (FRAP). Results: Eight (08) macroelements and five (05) trace elements from these plants have been quantified. The antioxidant potential showed that organic extracts were more active than aqueous extracts. However, this antioxidant potential remains low compared to that of ascorbic acid used as the reference antioxidant. Garcinia kola (seeds) and Ageratum conyzoides (leafy stems) were rich in mineral elements. Similarly, Cogniauxia podoleana (leaves) and Garcinia kola (seeds) showed remarkable antioxidant potential. Conclusion: The presence of thirteen mineral elements and the antioxidant potential are proved in these plants. Would therefore help to maintain the immunity of the human body by resisting various pathologies such as bacterial infections, malaria, inflammations and gastrointestinal disorders.

Synthesis and antioxidant properties of novel hybrid molecules containing gallic acid and thiazolidinone moieties

Thiazolidinones, are characterized by a thiazolidine ring structure, have highly biological applications. So, novel hybrid thiazolidinone moieties containing gallic acid were synthesized via cyclo-condensation process or standard Knoevenagel reactions. Hydrazineyl-thiazol-4(5H)-one 2 derivative was synthesized to condensed with benzaldehydes to afford benzylidene thiazolidinone derivatives 3a-c. Also, the product 2 reacted with benzyl bromide or nitro benzyl bromide to give their corresponding methylene active derivatives 4a,b which were readily reacted with aromatic aldehydes to produce 5-arylidene derivatives 5a-f via Knoevenagel reactions. The new thiazolidine derivatives were elucidated according to their spectroscopic and elemental analyses. Two thiazolidinone derivatives 4a,b were elucidated via X-ray analysis. Also, antioxidant activity of the new products were run by DPPH assay and in comparison with reference antioxidants (ascorbic acid and BHT). The results revealed that eight compounds was higher than BHT and was increasing in the following order 4a < 5f < 5a< 3c < 5b < 5d < 3a< 5c. The antioxidant activity of ascorbic acid was higher than all compounds in which compound 5c was very close in its activity with the ascorbic acid.

Wild Thymus zygis L. ssp. gracilis and Eucalyptus camaldulensis Dehnh.: Chemical composition, antioxidant and antibacterial activities of essential oils

Abstract Natural substances extracted from plants have been increasingly studied and recognized, recently. Essential oils (EOs), for example, possess antioxidant and antibacterial properties, enabling their application across different sectors like agro-food, pharmaceuticals, and cosmetics. In Morocco, exceptional plant diversity, mirroring the diversity of ecosystems, has not yet revealed all its secrets. Therefore, the aim of this study is to determine the chemical composition and evaluate the antibacterial and antioxidant activities of EOs from Thymus zygis L. ssp. gracilis and Eucalyptus camaldulensis Dehnh. collected in the El Hoceima and Mamora regions, respectively. The EOs were extracted by hydrodistillation employing a Clevenger-type apparatus. Gas chromatography/mass spectrometry (GC/MS) analyses identified 54 constituents representing 92.65% of the total for T. zygis and 55 components representing 99.60% for E. camaldulensis. The primary components found in the EO of T. zygis are δ-terpineol (27.64%), followed by δ-3-carene (15.7%), thymol (14.17%), and dehydrolinalool (4.99%). The main compounds in E. camaldulensis EO are 1,8-cineole (43.61%), γ-terpinene (11.71%), α-terpineol (10.58%), and p-cymene (4.93%). The antioxidant properties of these oils were investigated by utilization of the 2,2-diphenyl-1-picrylhydrazyl method and the ferric reducing antioxidant power (FRAP) test. The antibacterial activity was assessed against two Gram-positive bacteria (Staphylococcus aureus and Bacillus subtilis) and two Gram-negative bacteria (Micrococcus luteus and Escherichia coli). Both EOs showed significant antioxidant activity but were less effective than reference antioxidants quercetin and catechin. Antibacterial studies demonstrated strong activity of T. zygis and E. camaldulensis EOs against the studied bacteria, as well as good inhibitory properties (minimum inhibitory concentration).

Unveiling the Antioxidative Potential of Galangin: Complete and Detailed Mechanistic Insights through Density Functional Theory Studies.

A comprehensive quantum mechanical investigation delved into the antioxidative activity of galangin (Glg). Thermochemical and kinetic data were used to assess antiradical, chelating, and renewal potential under physiological conditions. A brief comparison with reference antioxidants and other flavonoids characterized Glg as a moderate antioxidative agent. The substance showed significantly lower performance in lipid compared to aqueous solvent─the reaction rates for scavenging •OOH in both media were established at 3.77 × 103 M-1 s-1 and 6.21 × 104 M-1 s-1, respectively, accounting for the molar fraction of both interacting molecules at the given pH. The impact of pH value on the kinetics was assessed. Although efficient at chelating Cu(II) ions, the formed complexes can still undergo the Fenton reaction. On the other hand, they persistently scavenge •OH in statu nascendi. The flavonoid effectively repairs oxidatively damaged biomolecules except model lipid acids. All Glg radicals are readily restored by physiologically prevailing O2•-. Given this, the polyphenol is expected to participate in antiradical and regenerating activities multiple times, amplifying its antioxidative potential.

Evaluation of antioxidant potential of crude extract of metabolites from endophytic fungi isolated from &lt;i&gt;Annona senegalensis&lt;/i&gt; Pers

Degenerative diseases resulting from free radicals can be prevented through the use of natural antioxidants. This study aimed to assess the free radical scavenging potential of the underexplored endophytic fungal metabolites from Annona senegalensis Pers (wild custard apple). Freshly collected root, midrib, and leaf tissues were planted on malt extract agar following surface sterilization with 70% ethanol for 3 minutes, washed twice with distilled water, immersed in a sodium hypochlorite solution (4%) for 5 minutes, and subsequently rinsed with sterile water. Seven endophytic fungi were isolated, and the antioxidant activity of their metabolites was evaluated using the 2,2- diphenyl-1-picrylhydrazyl free radical scavenging method, with ascorbic acid serving as a reference antioxidant. The crude extract from the seven endophytic fungal isolates demonstrated concentration- dependent antioxidant activities. LB2 exhibited a strong antioxidant activity with an IC50 value of 38.15 μg/ml. Extracts from RT1 and LB1 showed antioxidant activities, with the highest inhibition of 60% and 65%, respectively, observed at a concentration of 1000 μg/ml. This was compared favorably to ascorbic acid, which exhibited 94% inhibition. This indicates that the crude extract from endophytic fungi isolated from A. senegalensis possesses free radical scavenging properties. Further purification and elucidation of the crude extract will reveal the bioactive compounds responsible for the antioxidant activities.

Antioxidant Activity, Theaflavin, Total Polyphenol, and Catechin Composition of Camellia sinensis Processing Effluents from Various Factories in Kenya

Research into the antioxidant efficacy and sustainability implications of tea waste, a by-product of the rapidly growing global beverage industry, is increasingly necessary. This study scrutinized samples taken from various factories to explore their capacity for free radical scavenging and potential public health and environmental benefits. Analysis of the samples and reference antioxidant (BHT) revealed a notable dose- dependent rise in free-radical-scavenging action, implying a positive concentration-dependent antioxidant efficacy. Variations in antioxidant activity occurred from tea wastes sourced at various factories, alluding to geography having a pivotal effect on the biological contents and antioxidative capacity. Of particular interest were Boito's and Chelal's cyclone fluff samples that evinced relatively lower potency than those from other factories. Tombe factory's cyclone sample demonstrated a superior capacity for scavenging free radicals at different concentrations, suggesting that particular production or cultivation processes augmented its effectiveness. Notably, some tea waste samples even equalled the potency of BHT (a synthetic antioxidant) when augured to its highest level. Furthermore, this study revealed disparities in Theaflavin and Thearubigin content due to factors like maturation period and processing methods guiding these concentrations. We identified tea waste samples possessing remarkable polyphenol concentration, thereby providing valuable insights for consumers and industries. Further investigations on the chemical composition of tea waste phytocompounds are paramount due to their acclaimed health-promoting properties and the factors influencing their concentrations and antioxidant efficacy.

Volatile metabolites, antioxidant and biological activities of Bursera simaruba (L.) Sarg. essential oil, from the tropical dry forest, Cesar, Colombian Caribbean Region

Tropical Dry Forest (T-dF) is one of the most threatened ecosystems in the Neotropics, due to negative anthropogenic impacts on biodiversity and ecosystem services. Bursera simaruba (L.) Sarg. (indio desnudo, resbalamono), is among the species most reported for the T-dF of the Colombian Caribbean. In this work, the chemical composition and antioxidant and biological activities of B. simaruba essential oil (EO) were determined. EO chemical analysis from leaves and, petiole, and young branches bark (PYBB) of B. simaruba was carried out by Gas Chromatography coupled to Mass Spectrometry; polar and apolar columns were used for component separation. The biological activity of B. simaruba EO (PYBB) against Lasioderma serricorne (Coleoptera, Ptinidae) was determined by the preference area method. EO (PYBB) antioxidant capacity was determined by Oxygen Free Radical Absorbance Capacity (ORAC) assay. Reference antioxidant and standard terpenes were used for relative analysis of ORAC results. α-Terpinene (27.7% and 16.4%), p-cymene (22.8% and 44.0%), and g-terpinene (16.7% and 14.6%), were the main constituents in B. simaruba EOs (leaves and PYBB). EOs were represented by a high percentage of hydrocarbon monoterpenes (∼79.1% and ∼88.9%, leaves and PYBB); while hydrocarbon sesquiterpenes (∼3.1% and ∼4.6%, leaves and PYBB); contributed with a low percentage. B. simaruba EO (PYBB), showed attractant activity, at 0.4 μL.cm-2 (2h: -45%±7%; 4h: -50%±17%); in relation with Stay off, at 0.8 μL.cm-2, which was used as a positive control for repellent activity (2h: 66%±5%; 4h: 75%±21%). B. simaruba EO (PYBB) showed a very low antioxidant capacity (ORAC: 657.2±20.5 μmol Trolox/g sample), related to quercetin, used as reference antioxidant (50816.9±1559.1 μmol Trolox/g sample). However, EO ORAC was higher than the α-terpinene (68.0±10.8 μmol Trolox/g sample), γ-terpinene (51.2±2.0 μmol Trolox/g sample), p-cymene (105.6±6.4 μmol Trolox/g sample), used as standard terpenes. In conclusion, this is the first report on the chemical composition of the B. simaruba EO from Colombia, whose results differ from the previous ones from Jamaica and Guadeloupe. Chemical composition, reported here, with α-terpinene, γ-terpinene and p-cymene as principal compounds, could be used to establish a scientific support that explains some traditional uses. EO showed an attractive biological activity on L. serricorne. EO showed an antioxidant activity lowest quercetin (antioxidant reference), but higher that standard terpenes (α-terpinene, γ-terpinene and p-cymene).

Chemical profile and radical scavenging of the Psidium guajava flower’s essential oil: Molecular docking study on the human cytochrome P450 CYP2C9

Psidium guajava L. plant is frequently utilized as therapeutic plant due to its nutritional benefits and bioactive metabolites. The current study intends to identify the chemical characterization and antioxidant activity of essential oil (EO) of freshly harvested P. guajava flowers. The EO was analyzed using GC with flame-ionization detection (FID), gas chromatography-mass spectrometry (GC-MS) along with chemometric analysis. With 98.87% of overall oil mass, 37 volatile constituents were assigned. All identified compounds were categorized into two classes including mono-(30.34%) and sesquiterpenes (68.53%). The d-limonene (26.10%), trans-β-caryophyllene (17.24%), trans-nerolidol (11.01%), and ledol (5.12%) served as predominant compounds. Using three separate methods, DPPH, ABTS, and reducing power, the free radical scavenging activity of P. guajava flower oil was assessed in comparison with ascorbic acid as a reference antioxidant. The net results revealed that EO has considerable activities with respective IC50 values of 224.53, 125.78, and 231.78 mg L−1. All main compounds (> 3.00%) were in silico studied by Molecular Operating Environment (MOE) software on human cytochrome P450 CYP2C9. The net findings showed that the tested compounds have good binding affinity ranging from ΔG at −4.43 to −5.65 kcal/mol, while ascorbic acid exhibits binding affinity with ΔG = −4.58 kcal/mol. Cubenol revealed the best binding affinity with ΔG = −5.65 kcal/ mol. The present findings verified the guava flower EO’s powerful functions. For a better knowledge of the action pathways both in vitro and in vivo, more scientific studies on this oil’s antioxidant and/or its main components in pure form were advised.

The radical scavenging activity of 1-methyl-1,4-dihydronicotinamide: theoretical insights into the mechanism, kinetics and solvent effects.

1,4-Dihydronicotinamide derivatives, including 1-methyl-1,4-dihydronicotinamide (MNAH), are derivatives of the active center of nicotinamide coenzyme (NADH) and are therefore potent radical scavengers. MNAH serves as a useful model of NADH that allows for modeling studies to address the activity of this important biomolecule. In this work, MNAH activity was evaluated against typical free radicals using quantum chemical calculations in physiological environments, with a secondary aim of comparing activity against two physiologically relevant radicals of markedly different stability, HO˙, and HOO˙, to establish which of these is a better model for assessing antioxidant capacity in physiological environments. The HO˙ + MNAH reaction exhibited diffusion-limited overall rate constants in all media, including the gas phase. The HOO˙ antiradical activity of MNAH was also good, with overall rate constants of 2.00 × 104 and 2.44 × 106 M-1 s-1, in lipid and aqueous media, respectively. The calculated rate constant in water (k overall(MNAH + HOO˙) = 3.84 × 105 M-1 s-1, pH = 5.6) is in good agreement with the experimental data (k exp(NADH + HOO˙) = (1.8 ± 0.2)×105 M-1 s-1). In terms of mechanism, the H-abstraction of the C4-H bond characterized the HOO˙ radical scavenging activity of MNAH, whereas HO˙ could react with MNAH at several sites and following either of SET (in polar media), RAF, and FHT reactions, which could be ascribed to the high reactivity of HO˙. For this reason the results suggest that activity against HOO˙ is a better basis for comparison of anti-radical potential. In the broader context, the HOO˙ scavanging activity of MNAH is better than that of reference antioxidants such as trans-resveratrol and ascorbic acid in the nonpolar environment, and Trolox in the aqueous physiological environment. Therefore, in the physiological environment, MNAH functions as a highly effective radical scavenger.

Synthesis and computational evaluation of the antioxidant activity of pyrrolo[2,3-b]quinoxaline derivatives.

Pyrrolo[2,3-b]quinoxaline derivatives are known to possess antioxidant, anticancer, and antibacterial properties. Here we report the successful synthesis of five derivatives of 3-hydroxy-3-pyrroline-2-one through substitution. The 2,2-diphenyl-1-picrylhydrazyl (DPPH) assay was employed to evaluate the antioxidant activity of the compounds. Out of these, ethyl 1,2-diphenyl-1H-pyrrolo[2,3-b]quinoxaline-3-carboxylate (3a) demonstrated the greatest potential as a radical scavenger. Thermodynamic and kinetic calculations of the radical scavenging activity indicated that 3a exhibited HO˙ radical scavenging activity with the overall rate constant of 8.56 × 108 M-1 s-1 in pentyl ethanoate; however, it was incapable of scavenging hydroperoxyl radicals in nonpolar media. In non-polar environments, the hydroxyl radical scavenging capability of 3a is fairly similar to that of reference antioxidants such as Trolox, melatonin, indole-3-carbinol, and gallic acid. Hence, in the physiological lipid environment, 3a holds promise as a scavenger of HO˙ radicals.

Design, Synthesis and Biological Activity of the 4-Thioquinoline Derivative

One of the promising areas in the creation of bioregulators is the modeling of compounds that combine several pharmacophores. The design of new highly efficient and low-toxic cytoprotectors is largely based on the derivatives of nitrogen-containing heterocycles, and quinoline plays a significant role among these compounds. The researchers evaluated the toxicity of the tested compounds in silico, in vitro, and in vivo, which allowed determiningseveral factors that affect the level of toxic action of 4-thioquinoline derivatives and the direction of non-toxic substances in this sequence. The studied 4-thioquinolines showed a moderate antiradical action in the experiment, inferior to the reference antioxidant Acetylcysteine. The most active compounds are 7-chloro-4-thioquinoline derivatives with propanoic acid residues in the 4th position. 2-(7-chloroquinolin-4-ylthio)propanoic acid and sodium salt of 2-amino-3-((7-chloroquinolin-4-yl)thio)propanoic acid showed the most promising results and their antioxidant action was higher than Tiotriazolin (the comparator) by 27 % and 41 %, respectively. The studied compounds showed a protective effect under H2O2-induced oxidative stress against male sperm according to the main indicators of sperm fertility. It was found that the compounds withresidues of succinic acid, cysteamine, or cysteine in the molecule structure are not inferior to reference drugs. On average, 2-((7-chloroquinolin-4-yl)thio)succinic acid and 2-((quinolin-4-yl)thio)ethanaminedihydrochloride exceeded the comparison drug Acetylcysteine and were on a par with the effect of Ascorbic acid.