Synthesis,antioxidant, antifungal,molecular docking and ADMET studies of some thiazolyl hydrazones

Some thiazolyl hydrazones were synthesized by one pot reaction of thiophene-2-carbaldehyde or 2, 4-dichlorobenzaldehyde, thiosemicarbazide and various phenacyl bromides which were preliminarily screened for in vitro antioxidant and antifungal activities. Excellent DPPH and H₂O₂ radical scavenged antioxidant activities were observed with almost all the tested compounds. Compounds 4a, 4b, 4c, 4e, 4f and 4i showed comparable DPPH scavenged antioxidant potential (90.26–96.56%) whereas H₂O₂ scavenged antioxidant activity (90.98–92.08%) was noticeable in case of 4a and 4f; showing significant antioxidant potential comparable with the standard ascorbic acid (95.3%). In vitro antifungal activity of synthesized compounds against fungal species Candida albicance, Aspergillus niger and Aspergillus flavus was found to be moderate to good as compared with the standard fluconazole and MIC values were found in the range of 3.12–25 μg/mL. Molecular docking studies revealed that the compounds 4a, 4b and 4c have a potential to become lead molecules in drug discovery process. In silico ADMET study was also performed for predicting pharmacokinetic and toxicity profile of the synthesized antioxidants which expressed good oral drug like behaviour and non-toxic nature.     

Synthesis,antioxidant, and antimicrobial evaluation of some 2-arylbenzimidazole derivatives

A series of 2-arylbenzimidazole derivatives (3a–3p and 4a–4i) were synthesized and evaluated as potential antioxidant and antimicrobial agents. Their antioxidant properties were evaluated by various in vitro assays including hydroxyl radical (HO) scavenging, superoxide radical anion (O₂^?) scavenging, 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical scavenging, and ferric reducing antioxidant power. Results demonstrated that compounds with hydroxyl group at the 5-position of benzimidazole ring had a comparable or better antioxidant activity in comparison to standard antioxidant tert-butylhydroquinone (TBHQ). Markedly, compound 4h that showed the highest HO scavenging activity (EC₅₀ = 46 μM) in vitro had a significant reduction of 2,2′-azobis(2-amidinopropane) dihydrochloride (AAPH)-induced intracellular oxidative stress and H₂O₂-induced cell death. In addition, these compounds showed moderate to good inhibitory activity against Staphylococcus aureus selectively at noncytotoxic concentrations.     

Organochalcogen compounds from glycerol: Synthesis of new antioxidants

We describe here a simple method for the synthesis of glycerol derivatives containing an organochalcogen unit (Se, Te and S) using NaBH₄ and PEG-400 as a solvent. The new methodology was used to synthesize a range of new organochalcogen compounds in good yields. Furthermore, four of synthesized compounds were evaluated for their antioxidant activity using different assays, such as 2-azinobis-3-ethylbenzothiazoline-6-sulfonic acid (ABTS), 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical, nitric oxide (NO) and hydroxyl radical (OH) scavenging, ferric ion reducing antioxidant power (FRAP), ferrous ion chelating, superoxide dismutase-like activity and inhibition of linoleic acid lipid peroxidation. The new organotellurium 2,2-dimethyl-4-(phenyltellanylmethyl)-1,3-dioxolane 3j showed antioxidant activity and was more effective in inhibition of induced lipid peroxidation compared to solketal 4. Selenium and sulfur analogs 3a and 3m and solketal 4 did not present antioxidant effect. These findings suggest that 2,2-dimethyl-4-(phenyltellanylmethyl)-1,3-dioxolane 3j is a promising antioxidant and that its activity is influenced by the presence of the tellurium atom on the structure.     

Exploration of antimicrobial and antioxidant potential of newly synthesized 2,3-disubstituted quinazoline-4(3H)-ones

A series of 2-(chloromethyl)-3-(4-methyl-6-oxo-5-[(E)-phenyldiazenyl]-2-thioxo-5,6-dihydropyrimidine-1(2H)-yl)quinazoline-4(3H)-ones 9a-j was synthesized by treating 2-(chloroacetyl)amino benzoic acid with 3-amino-6-methyl-5-[(E)-phenyldiazenyl]-2-thioxo-2,5-dihydropyrimidine-4(3H)-one 8a-j and was screened for in vitro antibacterial activities against a representative panel of Gram-positive and Gram-negative bacteria. The compounds were synthesized in excellent yields and the structures were corroborated on the basis of IR, ¹H NMR, Mass and elemental analysis data. All the synthesized compounds elicited the potent inhibitory action against all the tested bacterial stains. Furthermore, in order to explore the antioxidant potential of newly synthesized compounds, the free radical scavenging activity measurement were performed by the 1,1-diphenyl-2-picryl-hydrazyl (DPPH) assay method. It is revealed from the antioxidant screening results that the compounds 9c and f manifested profound antioxidant potential.     

Synthesis,biological evaluation,and docking studies of novel 5,6-diaryl-1,2,4-triazine thiazole derivatives as a new class of α-glucosidase inhibitors

A novel 5,6-diaryl-1,2,4-triazine thiazole derivatives (7a-7q) were synthesized and characterized by ¹H NMR and ¹³C NMR and evaluated for their α-glucosidase inhibitory activity. All tested compounds displayed good α-glucosidase inhibitory activity with IC₅₀ values ranging between 2.85 ± 0.13 and 14.19 ± 0.23 μM when compared to the standard drug acarbose (IC₅₀ = 817.38 ± 6.27 μM). Compound 7i (IC₅₀ = 2.85 ± 0.13 μM) exhibited the highest activity among this series of compounds. Molecular docking studies were carried out in order to investigate the binding mode of this class of compounds to α-glucosidase. This study showed that these 5,6-diaryl-1,2,4-triazine thiazole derivatives are a new class of α-glucosidase inhibitors.     

Isolation and antioxidant activity evaluation of two new phthalate derivatives from seahorse, Hippocampus Kuda Bleeler

Seahorse (Hippocampus Kuda Bleeler) has been used as traditional medicine for thousands of years, in Eastern Asia. In this study of the methanol extract of fresh Hippocampus Kuda, the new compounds 2-ethyldecyl 2-ethylundecyl phthalate (1), 2, 12-diethyl-11-methylhexadecyl 2-ethyl-11-methylhexadecylphthalate (2), along with a known Bis(2-ethylheptyl) phthalate (3) were isolated. They were tested for their antioxidant activities, including lipid peroxidation inhibitory activity, DPPH radical scavenging, hydroxyl radical scavenging, superoxide anion radical scavenging, alkyl radical scavenging, and cellular radicals; these can be detected using a fluorescence probe, 2??,7??-dichlorofluorescin diacetate (DCFH-DA), which could be converted to highly fluorescent dichlorofluorescein (DCF) with the presence of intracellular ROS on mouse macrophages, RAW264.7 cell. Compound (2) exhibited the highest antioxidant activity and inhibitory intracellular ROS than another compounds (1, 3). Furthermore, MTT assay showed no cytotoxicity on mouse macrophages cell (RAW264.7) and human fetal lung fibroblast cell line (MRC-5). This antioxidant property depends on concentration and increasing with increased amount of the compound.     

Synthesis and biological evaluation of a novel series of pyrazole chalcones as anti-inflammatory,antioxidant and antimicrobial agents

A novel series of 1-(2,4-dimethoxy-phenyl)-3-(1,3-diphenyl-1H-pyrazol-4-yl)-propenone (3) have been prepared by the Claisen–Schmidt condensation of 1-(2,4-dimethoxy-phenyl)-ethanone (1) and substituted 1,3-diphenyl-1H-pyrazole-4-carbaldehydes (2). Substituted 1,3-diphenyl-1H-pyrazole-4-carbaldehydes (2) were prepared by Vilsmeir–Haack reaction on acetophenonephenylhydrazones to offer the target compounds. The structures of the compounds were established by IR, ¹H NMR and mass spectral analysis. All the compounds were evaluated for their anti-inflammatory (TNF-α and IL-6 inhibitory assays), antioxidant (DPPH free radical scavenging assay) and antimicrobial activities (agar diffusion method) against some pathogenic bacteria and fungi. Of 10 compounds screened, compounds 3a, 3c and 3g exhibited promising IL-6 inhibitory (35–70% inhibition, 10 μM), free radical scavenging (25–35% DPPH activity) and antimicrobial activities (MIC 100 μg/mL and 250 μg/mL) at varied concentrations. The structure–activity relationship (SAR) and in silico drug relevant properties (HBD, HBA, PSA, c Log P, molecular weight, E_HOMO and E_LUMO) further confirmed that the compounds are potential lead compounds for future drug discovery study. Toxicity of the compounds was evaluated theoretically and experimentally and revealed to be nontoxic except 3d and 3j.     

Flavonol glycosides and lignans from the leaves of Opilia amentacea

Two previously undescribed flavonol tetraglycosides, isorhamnetin-3-O-α-l-rhamnopyranosyl-(1→6)-β-d-galactopyranosyl-(1→4)-α-l-rhamnopyranosyl-(1→6)-β-d-glucopyranoside (1) and isorhamnetin-3-O-α-l-rhamnopyranosyl-(1→6)-β-d-galactopyranosyl-(1→4)-α-l-rhamnopyranosyl-(1→6)-β-d-galactopyranoside (2), along with nine known compounds including seven flavonoids and two lignans, were isolated from the leaves of Opilia amentacea Roxb (Opiliaceae). Their structures were established on the basis of spectroscopic analysis. The DPPH radical scavenging activity of compounds 1–11 was evaluated. In addition, all compounds were evaluated for their tyrosinase inhibitions by using in vitro mushroom tyrosinase assay. Only 5,5-dimethoxylariciresinol-4-O-β-d-glucopyranoside (10) and eleutheroside E1 (11) exhibited significant tyrosinase inhibition (IC₅₀ 42.1 and 28 μM, respectively) and DPPH radical scavenging activity (IC₅₀ 85.1 and 42.1 μM, respectively) compared with the positive controls.     

Synthesis and antioxidant properties of substituted 2-phenyl-1H-indoles

In this study, we report the design, synthesis and antioxidant activity of a series of substituted 2-(4-aminophenyl)-1H-indoles and 2-(methoxyphenyl)-1H-indoles. The new compounds are structurally related to the known indole-based antioxidant lead compound melatonin (MLT), and the antitumour 2-(4-aminophenyl)benzothiazole and 2-(3,4-dimethoxyphenyl)benzothiazole series. Efficient access to the target 2-phenylindoles was achieved via Fischer indole synthesis between substituted phenylhydrazines and acetophenones. 2-(4-Aminophenyl)indoles (such as the 6-fluoro analogue 3b) in particular showed potent antioxidant activity in the DPPH and superoxide radical scavenging assays (80% and 81% inhibition at 1 mM concentration of 3b, respectively), at a level comparable with the reference standard MLT (98% and 75% at 1 mM).     

Chemical constituents from Tribulus terrestris and screening of their antioxidant activity

Two oligosaccharides (1, 2) and a stereoisomer of di-p-coumaroylquinic acid (3) were isolated from the aerial parts of Tribulus terrestris along with five known compounds (4–8). The structures of the compounds were established as O-β-d-fructofuranosyl-(2 → 6)-α-d-glucopyranosyl-(1 → 6)-β-d-fructofuranosyl-(2 → 6)-β-d-fructofuranosyl-(2 → 1)-α-d-glucopyranosyl-(6 → 2)-β-d-fructofuranoside (1), O-α-d-glucopyranosyl-(1 → 4)-α-d-glucopyranosyl-(1 → 4)-α-d-glucopyranosyl-(1 → 2)-β-d-fructofuranoside (2), 4,5-di-p-cis-coumaroylquinic acid (3) by different spectroscopic methods including 1D NMR (¹H, ¹³C and DEPT) and 2D NMR (COSY, TOCSY, HMQC and HMBC) experiments as well as ESI-MS analysis. This is the first report for the complete NMR spectral data of the known 4,5-di-p-trans-coumaroylquinic acid (4).The antioxidant activity represented as DPPH free radical scavenging activity was investigated revealing that the di-p-coumaroylquinic acid derivatives possess potent antioxidant activity so considered the major constituents contributing to the antioxidant effect of the plant.     

Ultrasound mediated efficient synthesis of new 4-oxoquinazolin-3(4H)-yl)furan-2-carboxamides as potent tyrosinase inhibitors: Mechanistic approach through chemoinformatics and molecular docking studies

We have carried out the synthesis of new 4-oxoquinazolin-3(4H)-yl)furan-2-carboxamide derivatives by the reaction between isatoic anhydride, 2-furoic hydrazide and substituted salicylaldehydes in ethanol: water (5:5 v/v) solvent system using p-TSA as a catalyst under ultrasound irradiation at room temperature. The structures of newly synthesized compounds were confirmed through spectral techniques such as IR, ¹H NMR, ¹³C NMR, and LCMS. The important features of this protocol include simple and easy workup procedure, reaction carried out at ambient temperature, use of ultrasound and high yield of oxoquinazolin-3(4H)-yl)furan-2-carboxamides in short reaction time. The synthesized compounds 4a–4j were screened against tyrosinase enzyme and all these compounds found to be potent inhibitors with much lower IC₅₀ value of 0.028 ± 0.016 to 1.775 ± 0.947 µM than the standard kojic acid (16.832 ± 1.162 µM). The kinetics mechanism for compound 4e was analyzed by Lineweaver-Burk plots which revealed that compound inhibited tyrosinase non-competitively by forming an enzyme-inhibitor complex. Along with this all the synthesized compounds (4a–4j) were scanned for their DPPH free radical scavenging ability. The outputs received through in vitro and in silico analysis are coherent to the each other with good binding energy values (kcal/mol) posed by synthesized ligands.     

Optimization protocol for the extraction of antioxidant components from Origanum vulgare leaves using response surface methodology

In the present work, the response surface methodology (RSM) based on a central composite rotatable design (CCRD), was used to determine optimum conditions for the extraction of antioxidant compounds from Origanum vulgare leaves. Four process variables were evaluated at three levels (31 experimental designs): methanol (70%, 80%, and 90%), the solute:solvent ratio (1:5, 1:12.5, 1:20), the extraction time (4, 10, 16 h), and the solute particle size (20, 65, 110 micron). Using RSM, a quadratic polynomial equation was obtained by multiple regression analysis for predicting optimization of the extraction protocol. Analysis of variance (ANOVA) was applied and the significant effect of the factors and their interactions were tested at 95% confidence interval. The antioxidant extract (AE) yield was significantly influenced by solvent composition, solute to solvent ratio, and time. The maximum AE was obtained at methanol (70%), liquid solid ratio (20), time (16 h), and particle size (20 micron). Predicted values thus obtained were closer to the experimental value indicating suitability of the model. Run 25 (methanol:water 70:30; solute:solvent 1:20; extraction time 16 h and solute particle size 20) showed highest TP contents (18.75 mg/g of dry material, measured as gallic acid equivalents) and DPPH radical scavenging activity (IC₅₀ 5.04 μg/mL). Results of the present study indicated good correlation between TP contents and DPPH radical scavenging activity. Results of the study indicated that phenolic compounds are powerful scavengers of free radical as demonstrated by a good correlation between TP contents and DPPH radical scavenging activity.     

An aromatic amide C-glycoside and a cyclitol derivative from stem barks of Piper guineense Schum and Thonn (Piperaceae)

Two new compounds, an aromatic amide C-glycoside, 4-C-β-D-glucopyranosyl-3,5-dihydroxy-2-methoxybenzamide (1) and a cyclitol derivative, 4-O-caffeoyl-2-C-methoxycarbonyl-1-C-methyl-2,3,6-trihydroxycyclohexanecarboxylic acid (2), were isolated from the methanol soluble extract of the stem barks of Piper guineense Schum and Thonn, together with four known quinic acids derivatives including 3-O-caffeoyl-1-methylquinic acid (3), 3-O-feruloylquinic acid (4), ethyl-4-O-feruloylquinate (5), and 5-caffeoylquinic acid (6). Their structures were established on the basis of detailed spectroscopic analysis. The radical scavenging activity of the isolates were evaluated using 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical assay. Five of them were found to have significant radical scavenging activities, while compounds 2 and 3 displayed the highest activities with IC₅₀ values of 8.35 and 7.06 μM, respectively.     

Design,Synthesis, Antioxidant and Antibacterial Activities of Novel 2-((1-Benzyl-1<Emphasis Type="Italic">H</Emphasis>-1,2,3-Triazol-4-yl)methyl)-5-(2<Emphasis Type="Italic">H</Emphasis>Chromen- 3-yl)-2H-Tetrazoles

1,4-Disubstituted 1,2,3-triazole derivatives of 2H-chromene-3-tetrazoles synthesized regioselectively by copper(I)-catalyzed alkyne–azide cycloaddition (CuAAC) click reaction were characterized by ¹HNMR, ¹³C NMR, IR, and mass spectral data. These derivatives were screened for in vitro antioxidant activity using DPPH radical, H₂O₂ scavenging, and iron chelating activity methods and also evaluated for in vitro antibacterial activities against E. coli and S. aureus bacterial strains. The MIC and IC₅₀ values for all these compounds were found to match the docking scores and relevant binding energies with the receptor active sites. These results allows one to consider the compounds as leads for a new generation of antioxidant and antibacterial agents.     

Synthesis and antioxidant activity of novel Mannich base of 1,3,4-oxadiazole derivatives possessing 1,4-benzodioxan

A new series of Mannich base of 1,3,4-oxadiazole derivatives possessing 1,4-benzodioxan (6a–6ae) were synthesized and characterized by ¹H NMR, ESI-MS and elemental analysis. The structure of 6b was further confirmed by single crystal X-ray diffraction. All these novel compounds were screened for their in vitro antioxidant activity employing 2,2′-diphenyl-1-picrylhydrazyl radical (DPPH), 2,2′-azinobis (3-ethylbenzothiazoline-6-sulfonate) cationic radical (ABTS⁺) and ferric reducing antioxidant power (FRAP) scavenging assays. Due to the combination of 1,4-benzodioxan, 1,3,4-oxadiazoles and substituted phenyl ring, most of them exhibited nice antioxidant activities. In all of these three assays mentioned above, compounds 6f and 6e showed significant radical scavenging ability comparable to the commonly used antioxidants, BHT and Trolox. Seven compounds with representative substituents or activities were selected for further assays in chemical simulation biological systems—inhibition of microsomal lipid peroxidation (LPO) and protection against 2,2′-azobis (2-amidinopropane hydrochloride) (AAPH) induced DNA strand breakage, in which, 6f and 6e were demonstrated to be of the most potent antioxidant activities.     

Synthesis and biological evaluation of nitrogen-containing chalcones as possible anti-inflammatory and antioxidant agents

A novel series of nitrogen-containing chalcones were synthesized by Mannich reaction and were screened for anti-inflammatory related activities such as inhibition of cyclooxygenase-2 (COX-2), trypsin and β-glucuronidase. The antioxidant potential was demonstrated using 1,1-diphenyl-2-picryl hydrazine (DPPH) radical scavenging activity. The results of the above studies shows that the compounds synthesized were found to be effective inhibitors of above pro-inflammatory enzymes, and were found to be possess moderate radical scavenging potential. Overall, the results of the studies reveal that the chalcones with N-methyl piperazine methyl and piperidine methyl substitution (4c, 3b, 4d, 6b) seems to be important for inhibition of β-glucuronidase. Whereas the chalcones with piperidine methyl substitution (8b, 7b, 7c, 6c, 4b, 3c, 3b) were observed as effective inhibitors of COX-2, while the same compounds were found to be less reactive against COX-1 as compared to COX-2.     

Beilschglabrines A and B: Two new bioactive phenanthrene alkaloids from the stem bark of Beilschmiedia glabra

Two new phenanthrene alkaloids, beilschglabrines A (1) and B (2) were isolated from the stem bark of Beilschmiedia glabra, together with lupeol, taraxerol, and 24-methylenelanosta-7,9-diene-3β-15α-diol. The structures of the isolated compounds were elucidated by extensive spectroscopic data analysis and comparison with respective literature data. The compounds were tested for DPPH radical scavenging, acetylcholinesterase and lipoxygenase inhibitory activities. Compound 1 displayed considerable activity in the acetylcholinesterase (IC₅₀ 50.4 μM), the DPPH radical scavenging (IC₅₀ 115.9 μM) and the lipoxygenase (IC₅₀ 32.8 μM) assays.     

Bio-guided isolation of potential antimicrobial and antioxidant agents from the stem bark of Trilepisium madagascariense

Aim

This study describes the activity-guided isolation of antimicrobial and antioxidant agents from Trilepisium madagascariense stem bark.

Methods

The methanol crude extract of T. madagascariense was partitioned sequentially into n-hexane, ethyl acetate, n-butanol and the residual aqueous fractions. The ethyl acetate fraction was subjected to column chromatography and the structures of isolated compounds were elucidated using GC-MS and/or NMR data by comparing with those reported in the literature. Antimicrobial activity was assayed by agar well diffusion and broth microdilution techniques on 8 bacteria and 10 yeasts. The antioxidant activity was determined by DPPH radical scavenging method.

Results

The bioassay-guided fractionation of the crude methanol extract of T. madagascariense afforded two known compounds [vanillic acid () and isoliquiritigenin ()] and two mixtures of fatty acids (n-hexane fraction and first column fraction of ethyl acetate fraction, F1). The fractionation of the crude methanol extract enhanced the antimicrobial activity. Compound 2 was generally more active than compound 1. For all the tested samples, the most sensitive microbes were Enterococcus faecalis ATCC 10541 (MIC range of 60-780 μg/ml) for bacteria and Candida guillermondi (MIC range of 0.01-190 μg/ml) for yeasts. The DPPH radical scavenging activity (RSa) of compound 2 (RSa₅₀ = 28.73 μg/ml) was comparable to that of the crude methanol extract (RSa₅₀ = 29.92 μg/ml).

Conclusion

The antimicrobial activities and the antioxidant properties of the methanol crude extract, fractions and compounds 1 and 2 from the stem bark of T. madagascariense are being reported for the first time. These results may justify the traditional use of this plant for the treatment of gastrointestinal disorders.     

Syntheses,in vitro α-amylase and α-glucosidase dual inhibitory activities of 4-amino-1,2,4-triazole derivatives their molecular docking and kinetic studies

Thirty-three 4-amino-1,2,4-triazole derivatives 1–33 were synthesized by reacting 4-amino-1,2,4-triazole with a variety of benzaldehydes. The synthetic molecules were characterized via ¹H NMR and EI-MS spectroscopic techniques and evaluated for their anti-hyperglycemic potential. Compounds 1–33 exhibited good to moderate in vitro α-amylase and α-glucosidase inhibitory activities in the range of IC₅₀ values 2.01 ± 0.03–6.44 ± 0.16 and 2.09 ± 0.08–6.54 ± 0.10 µM as compared to the standard acarbose (IC₅₀ = 1.92 ± 0.17 µM) and (IC₅₀ = 1.99 ± 0.07 µM), respectively. The limited structure-activity relationship suggested that different substitutions on aryl part of the synthetic compounds are responsible for variable activity. Kinetic study predicted that compounds 1–33 followed mixed and non-competitive type of inhibitions against α-amylase and α-glucosidase enzymes, respectively. In silico studies revealed that both triazole and aryl ring along with different substitutions were playing an important role in the binding interactions of inhibitors within the enzyme pocket. The synthetic molecules were found to have dual inhibitory potential against both enzymes thus they may serve as lead candidates for the drug development and research in the future studies.     

Derivatives (halogen,nitro and amino) of 8-hydroxyquinoline with highly potent antimicrobial and antioxidant activities

8-Hydroxyquinoline (8HQ) compounds have been reported to possess diverse bioactivities. In recent years, drug repositioning has gained considerable attention in drug discovery and development. Herein, 8HQ (1) and its derivatives (2–9) bearing various substituents (amino, nitro, cyano and halogen) were investigated for their antimicrobial against 27 microorganisms (agar dilution method) and antioxidant (DPPH method) activities. The parent 8HQ (1) exerted a highly potent antimicrobial activity against Gram-positive bacteria including diploid fungi and yeast with MIC values in the range of 3.44–13.78 μM. Moreover, the halogenated 8HQ, especially 7-bromo-8HQ (4) and clioquinol (6), displayed a high antigrowth activity against Gram-negative bacteria compared with the parent compound (1). Apparently, the derivatives with a relatively high safely index, e.g., nitroxoline (2), exhibited strong antibacterial activity against Aeromonas hydrophila (MIC=5.26 μM) and selectively inhibited the growth of P. aeruginosa with the MIC value of 84.14 μM; cloxyquin (3) showed a strong activity against Listseria monocytogenes and Plesiomonas shigelloides with MIC values of 5.57 and 11.14 μM, respectively. Most compounds displayed an antioxidant activity. Specifically, 5-amino-8HQ (8) was shown to be the most potent antioxidant (IC₅₀=8.70 μM) compared with the positive control (α-tocopherol) with IC₅₀ of 13.47 μM. The findings reveal that 8HQ derivatives are potential candidates to be further developed as antimicrobial and antioxidant agents.