• Bulletin of the Korean Chemical Society
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• v.31 no.9
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• pp.2557-2560
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• 2010

To assay for antioxidant capacity of natural products considered important in producing human health benefits, a practical and economical method using pellet techniques was developed. A standard visualizing reagent, 1,1diphenyl-2-picryl-hydrazyl (DPPH), was mixed with a water-miscible polyvinyl alcohol (PVA), serving as a solid phase support for the DPPH reagent. A DPPH pellet was prepared by dropping a small volume of the DPPH solution onto PET film, and drying in an oven. The PVA-based DPPH pellet was dissolved into water, in which the water-miscible PVA plays as a non-ionic surfactant to help the DPPH reagent to be dissolved into the solvent. Using the DPPH assay, the antioxidant capacity of water-soluble extracts of black soybean, barley, green tea, and green gram was examined. Among the natural products tested, green tea showed the highest antioxidant capacity. This PVA-based DPPH antioxidant assay can be further applied in the natural food, raw plant material, and health product inspection field.

• Natural Product Sciences
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• v.22 no.1
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• pp.64-69
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• 2016

A method for simultaneously identifying antioxidative compounds was developed using time-based LC-MS coupled with DPPH assay regardless of the time consuming process. The methanolic extract of Polygonum aviculare (Polygonaceae) showed significant DPPH radical scavenging activity. Time-based DPPH assay for simultaneous identification of active compounds from the extracts of P. aviculare was used. Major peaks of ethyl acetate fraction of P. aviculare showed high DPPH radical scavenging activity. A simple phenolic compound (1) and six flavonoids (2-7) were isolated from the ethyl acetate fraction of P. aviculare by silica gel and sephadex LH-20 column chromatography. The structures of seven compounds were determined to be protocatechuic acid (1), catechin (2), myricitrin (3), epicatechin-3-O-gallate (4), avicularin (5), quercitrin (6), and juglanin (7) based on the analysis of the $^1H$-NMR, $^{13}C$-NMR and ESI-MS data. All compounds exhibited significant antioxidant activity on DPPH assay and active compounds were well correlated with predicted one.

• BMB Reports
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• v.37 no.5
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• pp.629-633
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• 2004

NADPH-cytochrome P450 reductase (CPR) transfers electrons from NADPH to cytochrome P450, and catalyzes the one-electron reduction of many drugs and foreign compounds. Various forms of spectrophotometric titration have been performed to investigate the electron-accepting properties of CPR, particularly, to examine its ability to reduce cytochrome c and ferricyanide. In this study, the reduction of 1,1-diphenyl-2-picrylhydrazyl (DPPH) by CPR was assessed as a means of monitoring CPR activity. The principle advantage of DPPH is that its reduction can be assayed directly in the reaction medium by a continuous spectrophotometry. Thus, electrons released from NADPH by CPR were transferred to DPPH, and DPPH reduction was then followed spectrophotometrically by measuring $A_{520}$ reduction. Optimal assay concentrations of DPPH, CPR, potassium phosphate buffer, and NADPH were first established. DPPH reduction activity was found to depend upon the strength of the buffer used, which was optimal at 100 mM potassium phosphate and pH 7.6. The extinction coefficient of DPPH was $4.09\;mM^{-1}\;cm^{-1}$. DPPH reduction followed classical Michaelis-Menten kinetics ($K_m\;=\;28\;{\mu}M$, $K_{cat}\;=\;1690\;min^{-1}$). This method uses readily available materials, and has the additional advantages of being rapid and inexpensive.

• Korean Journal of Pharmacognosy
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• v.46 no.4
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• pp.303-308
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• 2015

Ten phenolic compounds were isolated from the twigs of Stewartia pseudocamellia. The isolated compounds were identified as 5,7,3',5'-tetrahydroxyflavanone (1), 3,5,7,3',5'-pentahydroxyflavanone (2), quercetin (3), (+)-aromadendrin (4), (+)-ampelopsin (5), myricetin (6), (+)-catechin (7), (-)-epicatechin (8), kaempferol (9), and fraxin (10) by spectroscopic analysis. Compounds 1, 2, 4, 6, 8, and 9 were isolated from this plant for the first time. The antioxidant activities of compounds 1-10 were evaluated by the DPPH and/or ORAC (oxygen radical absorbance capacity) assay. Compounds 3, 5-9 showed significant antioxidative effects on DPPH assay. Among the active compounds, 6 exhibited higher activity compared to trolox on ORAC assay.

• Proceedings of the Plant Resources Society of Korea Conference
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• 2019.10a
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• pp.78-78
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• 2019

The aim of the study was to determine the antioxidant activities of the plants with origin of Vietnam. The Embelia scandens (Lour.) Mez which is a species of plant in the family Myrsinaceae and Cornus hongkongensis Hemsl., which is a species of plant in the family Cornaceae were tested for antioxidant activities. Samples were prepared using 95% ethanol using DPPH assay for assessing the antioxidant activity. Ascorbic acid was used for positive control for DPPH assay. DPPH assay experiment showed that extracts of the Embelia scandens (Lour.) Mez and Cornus hongkongensis Hemsl. might have anti-oxidant activity 4.77 times and 5.65 times higher, respectively, compared to control. To determine the cell toxicity, MTT (3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide) assay was used. MTT assay experiment showed that Embelia scandens (Lour.) Mez might have 13.1% more toxicity whereas Cornus hongkongensis Hemsl. might have 47.3% less toxicity compared to control. Taken together, these experiments showed that Cornus hongkongensis Hemsl. extracts might have significantly higher antioxidant activities and relatively lower toxicity, compared to control.

• Journal of the Korea Convergence Society
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• v.8 no.12
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• pp.215-220
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• 2017

Xanthium strumarium L. is an annual plant belongs to the family Asteraceae which is is called a 'Cocklebur' that is used for medicinal purposes. Convergent phyto-activity of various extracts of Xanthium strumarium L. (Asteraceae) was examined. We estimated antioxidant activity from ground part and fruit extract of X. strumarium using 1, 1-diphenyl-2-picrylhydrazyl radical (DPPH) and ABTS assay. The extract of X. strumarium was separated each fraction that of ethanol, petroleum ether, and ethyl acetate. It showed potent radical scavenging effect against the DPPH radical and ABTS. The study revealed that X. strumarium could be used as a potential source of natural antioxidant.

• Microbiology and Biotechnology Letters
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• v.41 no.3
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• pp.367-371
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• 2013

The half maximal inhibitory concentration ($IC_{50}$) values and trolox equivalent antioxidant capacity (TEAC) values were calculated by a 2,2'-diphenylpicrylhydrazyl (DPPH) assay and a 2,2'-azino-bis-3-ethylbenzothiazoline-6-sulfonic acid ($ABTS^{+{\cdot}}$) assay, in order to determine the antioxidative activities of the compounds. On the basis of the DPPH assay, quercetin had the strongest antioxidative potential of the flavonoids, followed in order by fisetin, 7,8-dihydroxyflavone, morin and kaempferol. Quercetin, fisetin and 7,8-dihydroxyflavone had higher antioxidant potentials than butyl hydroxyl anisole. Quercetin had the highest TEAC value amongst the flavonoids and isoflavonoids, followed in order by 3-hydroxyflavone, fisetin, 7,8-dihydroxyflavone and morin. Comparatively, isoflavonoids were found to have significantly weaker antioxidative potential than the flavonoids.

• Microbiology and Biotechnology Letters
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• v.40 no.3
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• pp.208-214
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• 2012

Chaff-vinegar is known for having a variety of useful purposes in the fields of health and lifestyles. In a previous study we isolated and identified the active fractions of the polyphenol compound 7 species as a potential biomaterial for cosmeceuticals. To further test for its potential use as a functional material, we carried out an MTT assay, collagenase inhibition assay, elastase inhibition assay, tyrosinase inhibition assay, DPPH free radical scavenging assay, SOD-like activity assay and a xanthine oxidase inhibition assay. Chaff-vinegar exhibited potent collagenase and elastase inhibitory activities in a concentration dependent manner, indicating that the agent has the potential to alleviate the skin wrinkling process. Chaff-vinegar also showed 80% tyrosinase inhibition at a concentration of $100{\mu}L/mL$. DPPH radical scavenging, xanthine oxidase inhibition, and SOD-like activity results for each activity were 80%, 80%, and 100%, respectively. Taken together, the present study suggests that chaff-vinegar is a good candidate for use as an anti-wrinkling and/or whitening agent.

• Korean Journal of Plant Resources
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• v.22 no.4
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• pp.323-329
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• 2009

In order to find out superior corn line which has a strong antioxidant activity in the corn silk, antioxidant compounds and antioxidant activity were measured from various inbred and F1 lines. As a result, the contents of phenolic and flavonoid compounds range from 532 mg/100 g to 3,274 mg/100 g and from 980 mg/100 g to 2,420 mg/100 g respectively. Absorbance at 517 nm for contents of anthocyanins ranges from 0.05 to 0.76. Correlation coefficients between antioxidant compounds and various antioxidant assays such as DPPH, ABTS and FRAP were analyzed. Correlation coefficients between antioxidant activity and phenolic compounds and anthocyanin were significantly high in ABTS and FRAP assays. Considering acidic extraction condition and intervention between anthocyanins and DPPH solution, ABTS assay and FRAP assay are more suitable methods to evaluate antioxidant activity of corn silks. Especially, ABTS assay is thought to be the best method among three assays because the antioxidant activity in ABTS assay showed high correlation with phenol, flavonoid and anthocyanin compounds respectively. Among the samples, S15 which showed the highest contents of total phenolic compounds and the most potent antioxidant activity in ABTS and FRAP assay will be a good source for functional material.

• The Korean Journal of Food And Nutrition
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• v.24 no.4
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• pp.713-719
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• 2011

The antioxidant activities of the ethanol extract of Arctium lappa were assessed by measuring the 1,1-diphenyl-2-picrylhydrazyl( DPPH) radical scavenging effect, inhibition of $Fe^{2+}$-induced lipid peroxidation, inhibition of malondialdehyde(MDA)-bovine serum albumin(BSA) conjugation reaction and antimutagenic capacities using the Ames test. The DPPH radical scavenging activity and inhibition of $Fe^{2+}$-induced lipid peroxidation of the $Arctium$ $lappa$ ethanol extract significantly increased in a dose-dependent manner. In the radical scavenging assay using DPPH, the $IC_{50}$ of the Arctium lappa extract was 296 ${\mu}g$/assay(1.29 mg of dry sample). In addition, the $IC_{50}$ in the inhibition of $Fe^{2+}$-induced lipid peroxidation was 1,759 ${\mu}g$/assay(7.65 mg of dry sample). This extract also significantly inhibited the MDA-BSA conjugation reaction with an $IC_{50}$ of 57.58 mg/assay(250 mg of dry sample). However, no inhibitory effects against the direct and indirect mutagenicities in $Salmonella$ Typhimurium TA98 and TA100 were observed. Based on these results, the ethanol extract of $Arctium$ $lappa$ was shown to display considerable antioxidative activities.