Antioxidant Activity Of Phenolic Compounds Research Articles

Anti-HSV-1, antioxidant and antifouling phenolic compounds from the deep-sea-derived fungus Aspergillus versicolor SCSIO 41502

Chemical investigation of the deep-sea-derived fungus Aspergillus versicolor SCSIO 41502 resulted in the isolation of three new anthraquinones, aspergilols G-I (1–3), one new diphenyl ether, 4-carbglyceryl-3,3′-dihydroxy-5,5′-dimethyldiphenyl ether (4), and one new benzaldehyde derivative, 2,4-dihydroxy-6-(4-methoxy-2-oxopentyl)-3-methylbenzaldehyde (5), along with 23 known phenolic compounds (6–28). The structures of new compounds were elucidated by extensive spectroscopic analysis. The absolute configuration of 3 was established by CD spectrum and the modified Mosher method. Compounds 2, 3 and 9 had evident antiviral activity towards HSV-1 with EC50 values of 4.68, 6.25, and 3.12μM, respectively. Compounds 15, 18, 20 and 22–24 showed more potent antioxidant activity than l-ascorbic acid with IC50 values of 18.92–52.27μM towards DPPH radicals. Comparison of the structures and antioxidant activities of 1–28 suggests that the number of phenolic hydroxyl group that can freely rotate can significantly affect the antioxidant activity of phenolic compounds. In addition, 4, 22–24 and 27 had significant antifouling activity against Bugula neritina larval settlement with EC50 values of 1.28, 2.61, 5.48, 1.59, and 3.40μg/ml, respectively.

Phenolic Profiles and Antioxidant Activity of Lotus Root Varieties.

Lotus root attracts increasing attention mainly because of its phenolic compounds known as natural antioxidants. Its thirteen varieties were systematically analyzed on the content, distribution, composition and antioxidant activity of phenolic compounds for a better understanding of this aquatic vegetable. The respective mean contents of total phenolics in their flesh, peel and nodes were 1.81, 4.30 and 7.35 mg gallic acid equivalents (GAE)/g fresh weight (FW), and those of total flavonoids were 3.35, 7.69 and 15.58 mg rutin equivalents/g FW. The phenolic composition determined by a high-performance liquid chromatography method varied significantly among varieties and parts. The phenolics of flesh were mainly composed of gallocatechin and catechin; those of peel and node were mainly composed of gallocatechin, gallic acid, catechin and epicatechin. The antioxidant activities of phenolic extracts in increasing order were flesh, peel and node; their mean concentrations for 50% inhibition of 2,2-diphenyl-1-picrylhydrazyl radical were 46.00, 26.43 and 21.72 µg GAE/mL, and their mean values representing ferric reducing antioxidant power were 75.91, 87.66 and 100.43 µg Trolox equivalents/100 µg GAE, respectively. “Zoumayang”, “Baheou”, “No. 5 elian” and “Guixi Fuou” were the hierarchically clustered varieties with relatively higher phenolic content and stronger antioxidant activity as compared with the others. Especially, their nodes and peels are promising sources of antioxidants for human nutrition.

Antioxidant Activity of Phenolic Compounds from Fava Bean Sprouts.

Fava beans are eaten all over the world and recently, marketing for their sprouts began in Japan. Fava bean sprouts contain more polyphenols and l-3,4-dihydroxyphenylalanine (l-DOPA) than the bean itself. Our antioxidant screening program has shown that fava bean sprouts also possess a higher antioxidant activity than other commercially available sprouts and mature beans. However, the individual constituents of fava bean sprouts are not entirely known. In the present study, we investigated the phenolic compounds of fava bean sprouts and their antioxidant activity. Air-dried fava bean sprouts were treated with 80% methanol and the extract was partitioned in water with chloroform and ethyl acetate. HPLC analysis had shown that the ethyl acetate-soluble parts contained phenolic compounds, separated by preparative HPLC to yield 5 compounds (1-5). Structural analysis using NMR and MS revealed that the compounds isolated were kaempferol glycosides. All isolated compounds had an α-rhamnose at the C-7 position with different sugars attached at the C-3 position. Compounds 1-5 had β-galactose, β-glucose, α-rhamnose, 6-acetyl-β-galactose and 6-acetyl-β-glucose, respectively, at the C-3 position. The amount of l-DOPA in fava bean sprouts was determined by the quantitative (1) H NMR technique. The l-DOPA content was 550.45 mg ± 11.34 /100 g of the raw sprouts. The antioxidant activities of compounds 2-5 and l-DOPA were evaluated using the 2,2-diphenyl-1-picrylhydrazyl scavenging assay. l-DOPA showed high antioxidant activity, but the isolated kaempferol glycosides showed weak activity. Therefore, it can be suggested that l-DOPA contributed to the antioxidant activity of fava bean sprouts.

Extraction and antioxidant activity of phenolic compounds from wheat bran treated by steam explosion

Purpose : To use response surface methodology to optimize the extraction of the phenolic compounds in wheat bran treated by steam explosion, and to determine the antioxidant activity of the extract obtained. Methods : By using response surface methodology, the effects of extraction time, methanol concentration, liquid/solid and temperature were studied and optimized. 2,2-Diphenyl-1-(2,4,6- trinitrophenyl) hydrazyl (DPPH) radical-scavenging capacity, reducing capacity and 2,2′-Azino-bis(3- ethylbenzothiazoline-6-sulfonic acid) diammonium salt (ABTS) radical scavenging capacity were also employed to determine antioxidant activity of the extract. Results : Under the optimal conditions, i.e., extraction time: 120 s, ethanol content: 43 %, liquid/solid: 35:1, temperature: 70 o C, the experimental total phenolic yield was 30.464 ± 0.025, which agreed with the predicted value of 31.687. The phenolic compounds showed strong antioxidant activities. At extract concentration of 1 mg/ml, DPPH radical-scavenging activity was 50 %. Although its reducing power (2 – 10 mg/mL) was lower than that of BHA, ABTS radical scavenging of the extract (close to 90 %) was higher than that of BHA at extract concentration > 6 mg/mL. Conclusion : The yield of the phenolic compounds was high and the compounds displayed strong antioxidant capacity, which indicates that the extraction of wheat bran under steam explosion holds high potentials for the food and pharmaceutical industries. Keywords : Wheat bran, Steam explosion, Extraction, Response surface methodology, Antioxidant capacity

Extraction and Antioxidant Activity of Phenolic Compounds from <i>Okra</i> Flowers

Purpose : To investigate the extraction and antioxidant activity of phenolic compounds from Okra flowers. Methods : The phenolic compounds in Okra flowers was obtained by traditional solvent extraction method and determined by Folin-Ciocalteu (FC) method. The extraction was optimized using response surface methodology (RSM). The antioxidant activity of the obtained extract was determined by 1,1- diphenyl-2-picrylhydrazyl (DPPH) radical scavenging and reducing power assays. Results : The optimal extraction conditions were as follows: extraction time, 2.5 h; ethanol concentration, 59.16 %; extraction temperature, 73.91 °C; and liquid-solid ratio, 20 mL/g. The mean total phenolics yield under the optimum conditions was 40.77±0.83 mg GAE /g material, which is near the predicted value of 44.20 mg GAE /g material. The total phenolics of the extract was an effective scavenger in quenching DPPH radicals. A linear correlation between the concentration of the total phenolics extract and reducing power was observed with a correlation coefficient (r2) of 0.9973. Conclusion : Using RSM, the extraction of total phenolics in okra flowers has been optimized. The extract exhibits a strong DPPH radical scavenging activity and reducing power, which makes it a potential functional ingredient in the food and pharmaceutical industries. Keywords : Okra flowers, Extraction, Response surface methodology, Phenolics, Antioxidant

Structural Characterization and Evaluation of the Antioxidant Activity of Phenolic Compounds from Astragalus taipaishanensis and Their Structure-Activity Relationship.

Eight phenolic compounds were isolated using bio-guided isolation and purified from the roots of Astragalus taipaishanensis Y. C. Ho et S. B. Ho (A. taipaishanensis) for the first time. Their structures were elucidated by ESI-MS, HR-ESI-MS, 1D-NMR and 2D-NMR as 7,2′-dihydroxy-3′,4′-dimethoxy isoflavan (1), formononetin (2), isoliquiritigenin (3), quercetin (4), kaempferol (5), ononin (6), p-hydroxybenzoic acid (7) and vanillic acid (8). Six flavonoids (compounds 1-6) exhibited stronger antioxidant activities (determined by DPPH, ABTS, FRAP and lipid peroxidation inhibition assays) than those of BHA and TBHQ and also demonstrated noticeable protective effects (particularly quercetin and kaempferol) on Escherichia coli under oxidative stress. Additionally, the chemical constituents compared with those of Astragalus membranaceus and the structure-activity relationship of the isolated compounds were both analyzed. The results clearly demonstrated that A. taipaishanensis has the potential to be selected as an alternative medicinal and food plant that can be utilized in health food products, functional tea and pharmaceutical products.

Phytochemical Study and Evaluation of the Antimicrobial and Antioxidant Activity of Essential Oils and Phenolic Compounds of Pistacia Lentiscus L

This work aims for the phytochemical study and evaluation of the antioxidant activity of phenolic compounds and essential oils of medicinal plant Pistacia lentiscus L. quantitatively and qualitatively. Through the results obtained, it appears that the leaves and fruits are rich in substances with a high antioxidant power. The yield of the phenolic compounds obtained from 10g to powder of plant is for leaves 116.49 % and 61.34 % for fruit . For essential oils, it is 0.253 ± 0.131 % for 100 g of plant material. The chromatographic profile of the essential oil of Pistacia lentiscus L. shows that monoterpenes are the major compound (9.675 % of identified molecules). The strong antioxidant activity of extracts obtained only confirms the traditional use of this plant by the local population. Keywords : Chromatographic profile ; monoterpenes , secondary metabolites ; Boumerdes

Simulated gastrointestinal digestion and in vitro colonic fermentation of spent coffee (Coffea arabica L.): Bioaccessibility and intestinal permeability

Spent coffee, a waste produced after beverage preparation, contains large amounts of several human health related compounds. The bioaccessibility, permeability and antioxidant activity of phenolic compounds from spent coffee (medium and dark-roasted) were evaluated using an in vitro gastrointestinal assay, intestinal absorption and colonic fermentation of non-digestible spent coffee fraction. Digested samples displayed lower amounts of phenolic compounds and flavonoids, but higher antioxidant activity (1–8 folds) compared to their respective non-digested (undigested) controls due to high release of condensed tannins at the colonic stage. SC polyphenols released during simulated GI digestion scavenged free radicals and these antioxidants increased during the transition from acidic to alkaline environment rapidly permeating through the small intestine by passive diffusion. Our results highlight the in vivo potential physiological role of SC phenolic compounds to scavenge free radicals present in the systemic circulation and target tissues, suggesting their potential health benefits and justifying their value addition. Further studies are needed to elucidate the clinical implication of these findings in human subjects.

Anti-oxidant Activity of Phenolic Compounds and Simultaneous Contents Determination using HPLC-UV from the Akebiae caulis

Anti-oxidant Activity of Phenolic Compounds and Simultaneous Contents Determination using HPLC-UV from the Akebiae caulis

Depletion/protection of β-carotene in estimating antioxidant activity by β-carotene bleaching assay

The β-carotene bleaching assay belongs to the oldest and commonly applied methods of estimating the antioxidant activity of different substances and mixtures. In this method, the antioxidant activity of the examined substance is evaluated by the spectrophotometric measurement of β-carotene concentration changes in β-carotene/peroxyl radicals (LOO•) systems with and without antioxidant. The presented results confirm the essential influence of hydrogen ion concentration on the estimation of antioxidant activity of phenolic compounds and prove that the formation of peroxyl radicals in measuring system is inhibited by the presence of hydrogen ions. Contrary to hydrogen ions, alkali metal ions accelerate the formation of peroxyl radicals quickening β-carotene depletion, thus indicating the seemingly weaker antioxidant properties of the antioxidant at the presence of metal ions. The LOO•/β–carotene reaction rate, and hence the estimated antioxidative potential of the examined compound, is also dependent on the type and concentration of the anion accompanying the cation. The presented results show the difficulty in the estimation of true antioxidant properties of food components, plant extracts and even antioxidant additives protecting products against oxidative changes.

Antioxidant activity of phenolic compounds added to a functional emulsion containing omega-3 fatty acids and plant sterol esters

The effect of eleven compounds extracted from red propolis on the oxidative stability of a functional emulsion was evaluated. Emulsions prepared with Echium oil as omega 3 (ω-3 FA) source, containing 1.63g/100mL of α-linolenic acid (ALA), 0.73g/100mL of stearidonic acid (SDA) and 0.65g/100mL of plant sterol esters (PSE) were prepared without or with phenolic compounds (vanillic acid, caffeic acid, trans-cinnamic acid, 2,4-dihydroxycinnamic acid, p-coumaric acid, quercetin, trans-ferulic acid, trans,trans-farnesol, rutin, gallic acid or sinapic acid). tert-Butylhydroquinone and a mixture containing ascorbic acid and FeSO4 were applied as negative and positive controls of the oxidation. Hydroperoxide, thiobarbituric acid reactive substances (TBARS), malondialdehyde and phytosterol oxidation products (POPs) were evaluated as oxidative markers. Based on hydroperoxide and TBARS analysis, sinapic acid and rutin (200ppm) showed the same antioxidant activity than TBHQ, representing a potential alternative as natural antioxidant to be applied in a functional emulsion containing ω-3 FA and PSE.

Evaluation of antioxidant action by electrochemical and accelerated oxidation experiments of phenolic compounds derived from cashew nut shell liquid

This paper describes the use of electrochemical methods and accelerated oxidation experiments (EN 14112, Rancimat method) for the determination of antioxidant activity of phenolic compounds (cardanol, cardol and tert-butylated cardanol) derived from cashew nut shell liquid (CNSL), a byproduct obtained during the processing of cashew nuts classified as a renewable raw material, natural of low-value. Through the electrochemical study, having as reference the anodic peak potential (Epa) and peak current (Ip), was observed that the cardol had the best performance, followed by tert-butylated cardanol and this by cardanol, showing that the presence of electron-donating groups as tert-butyl and hydroxyl exerts a positive influence on the antioxidant action of these compounds. These analyzes showed also that unsaturated compounds presented current values superior than saturated ones, indicating that the unsaturated molecules participate in greater number of the electro-oxidation process. The accelerated oxidation experiments were performed through analysis of biodiesel samples additivated with CNSL-based antioxidants at 500ppm, and the same sequence of activity presented by the electrochemical study was observed, showing that this class of compounds can be applied effectively to inhibit the oxidative process of biofuel.

Isolation and identification of phenolic antioxidants in black rice bran.

Black rice bran contains phenolic compounds of a high antioxidant activity. In this study, the 40% acetone extract of black rice bran was sequentially fractionated to obtain 5 fractions. Out of the 5 fractions, ethyl acetate fraction was subfractionated using the Sephadex LH-20 chromatography. The antioxidant activity of phenolic compounds in the extracts was investigated by 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical assay, 2,2-azino-bis-(3-ethylenebenzothiozoline-6-sulfonic acid) (ABTS) radical cation assay, reducing power. The subfraction 2 from ethyl acetate fraction had the highest total phenolic contents (TPC) (816.0 μg/mg) and the lowest EC50 values (47.8 μg/mL for DPPH radical assay, 112.8 μg/mL for ABTS radical cation assay, and 49.2 μg/mL for reducing power). These results were 3.1, 1.3, and 2.6 times lower than those of butylated hydroxytoluene (BHT), respectively. At a concentration of 100 μg/mL, the antioxidant activity and TPC of various extracts was closely correlated, with correlation coefficients (R(2) ) higher than 0.86. The major phenolic acid in subfraction 2 was identified as ferulic acid (178.3 μg/mg) by HPLC and LC-ESI/MS/MS analyses. Our finding identified ferulic acid as a major phenolic compound in black rice bran, and supports the potential use of black rice bran as a natural source of antioxidant.

Stability, antioxidant activity and in vitro bile acid-binding of green, black and dark tea polyphenols during simulated in vitro gastrointestinal digestion

The stability and antioxidant activity of phenolic compounds, as well as the bile acid-binding activity of green, black, raw liubao and aged liubao tea duringin vitrogastrointestinal digestion were evaluated.

In vitro assessment of antioxidant activity of tyrosol, resveratrol and their acetylated derivatives

Consumption of phenolic compounds is associated with beneficial effects in humans even though many of them are poorly absorbed. The aim of this study was to investigate the in vitro antioxidant activity of tyrosol (T), resveratrol (R) and their acetylated derivatives (AcD), as increased lipophilicity has been reported to improve absorption.The chemically synthesized AcDs were evaluated by their ability to scavenge DPPH radicals, inhibit non-enzymatic linoleic acid peroxidation, inhibit human serum oxidation in the presence of copper ions and inhibit lipoxygenase activity.T showed an inhibitory effect only in serum oxidation, where the T-acetylated at aromatic-OH was the most active. The T-acetylated at aliphatic-OH and 3,5-diacetyl-R exhibited the most powerful effect in non-enzymatic linoleic acid peroxidation with IC50 values 2.4mM±0.21 and 0.055mM±0.0018, respectively. In all other tests R was the most potent among all its AcD and T.Increasing lipophilicity by acetylation improves antioxidant activity of phenolic compounds in non-enzymatic lipid peroxidation assays.

Antioxidative activity of Silibum marianum cultivated in Mongolia

Silibum marianum (Milk thistle) contains high amount of phenolic compounds with antioxidant properties. The aim of this work was to evaluate the antioxidant activity of phenolic compounds included in Milk thistle. The antioxidant properties of the leaves and seeds of milk thistle were examined by determining its ability to scavenge the 2,2-diphenyl-1-picrylhydrazyl (DPPH) free radical. The results obtained from DPPH assay confirm that Milk thistle extracts have high antioxidative activity.DOI: http://doi.dx.org/10.5564/mjc.v15i0.323 Mongolian Journal of Chemistry 15 (41), 2014, p53-55

Antioxidant activity of phenolic compounds from canola (Brassica napus) seed

The antioxidant activities of various extracts from canola (Brassica napus) seed were investigated using the DPPH assay, ABTS radical assay, and reducing power. An 80% methanol extract from canola seed was sequentially fractionated and separated according to the solvent polarity and Sephadex LH-20 chromatography, respectively. The antioxidant activities of various extracts and their total phenolic content (TPC) and total flavonoid content (TFC) were closely correlated, resulting in correlation coefficient values higher than 0.87. Of all extracts, the sub-fraction 3 had the highest TPC (462.3 μg/mg) and TFC (75.4 μg/mg) while it showed the lowest EC50 value (183.1 μg/mL). The EC50 value of sub-fraction 3 measured using the DPPH radical assay was 1.3 times lower than that of butylated hydroxytoluene (BHT). The major free phenolic compound was trans-sinapic acid (193.4 μg/mg) and sinapic acid derivatives identified as 1-O-β-d-glucopyranosyl sinapate and 1,2-di-O-sinapoyl-β-d-glucose in sub-fraction 3.

Evaluation of anticandidal and antioxidant activities of phenolic compounds from Pyrostegia venusta (Ker Gawl.) Miers.

We have investigated the in vitro anticandidal and antioxidant activities of phenolic compounds from Pyrostegia venusta flower extracts. We used the HPLC technique to purify the flavonoid (quercetin-3-O-α-l-rhamnopyranosyl-(1→6)-β-d-galactopyranoside) and two phenylpropanoid glycosides (verbascoside and isoverbascoside); we evaluated the antimicrobial activity of the extracts against Candida strains (Candidaalbicans; Candidakrusei ATCC 6258; and the clinical isolate strains of Candida sp. C. albicans, C. krusei, Candidatropicalis, Candidaparapsilosis, and Candidaguilhermondii). The P. venusta flower extracts displayed antimicrobial and antioxidant activities. The semi-purified fraction of the P. venusta flower extract and the phenylpropanoid glycoside verbascoside exhibited activity similar to that of amphotericin B, which denoted that they are potentially applicable as natural antioxidant and anticandidal agents in the pharmaceutical industries.

Structure and antioxidant activity of phenolic compounds isolated from the edible fruits and stem bark of Harpephyllum caffrum

Antioxidant activity in edible fruits is an important characteristic in the choice of fruits for human consumption, and has profound influence on nutrition and health. Two pharmacologically active triterpenoids, β-sitosterol and lupeol, and the powerful flavan-3-ol antioxidant, (+)-catechin, were isolated from the edible fruits of Harpephyllum caffrum while a mixture of cardanols, an alkyl p-coumaric acid ester, and (+)-catechin were isolated from the stem bark. This is the first report of these compounds being isolated from this plant. The antioxidant capacity of (+)-catechin was higher than the other isolated compounds as well as the known antioxidant, ascorbic acid.

Evaluation of the anti-osteoporosis and antioxidant activities of phenolic compounds from Euphorbia maculata

Antioxidant and anti-osteoporosis activities of extracts and chemical constituents from the whole plant of Euphorbia maculata were investigated. The MeOH extract, as well as EtOAc and H2O fractions (10.0 μg/mL), exhibited potent antioxidant activities. Their oxygen radical absorbance capacity and cupric ion reducing antioxidant capacity values were 27.07±0.31 to 28.47±0.36 and 43.86±0.26 to 46.67±0.34 fold higher than those of 1.0 μM Trolox, respectively. The MeOH extract and EtOAc fraction (at 10.0 μg/mL) also significantly suppressed excessive bone resorption by osteoclasts with tartrate-resistant acid phosphatase (TRAP) activity values of 154.90±4.25 and 163.95±9.77%, respectively. Bioassay guided isolation of the EtOAc and H2O fractions afforded 19 known compounds (1–19). Of these, compounds 18, and 13–15 showed good antioxidant activity based on peroxyl radical-scavenging and reducing capacity assays, whereas compounds 1, 4, 7, and 14 showed the most significant inhibitory effect with TRAP activity values ranging from 121.31±1.41 to 110.00±3.74% relative to the control.