• Archives of Pharmacal Research
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• v.26 no.1
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• pp.24-27
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• 2003

A furanofuranoid lignan glycoside, with radical scavenging on peroxynitrite, total reactive oxygen species (ROS) and 1, 1-diphenyl-2-picrylhydrazyl (DPPH) radical, was isolated from the rhizome of Salvia miltiorrhiza and characterized as (+)-1-hydroxypinoresinol-1-Ο-$\beta$-D-glucoside based on spectroscopic evidence. The compound exhibited peroxynitrite, total ROS and DPPH radical scavenging activities with $IC_{50}$ values of 3.23$\pm$0.04, 2.26$\pm$0.07 and 32.3$\pm$0.13 $\mu$M, respectively. Penicillamine, Trolox (6-hydroxy-2,5,7,8-tetramethylchroman-2-carboxylic acid) and L-ascorbic acid, acting as positive controls, showed radical scavenging activities with $IC_{50}$ values of 6.72$\pm$0.25, 1.43$\pm$0.04 and 11.4$\pm$0.07 $\mu$M, respectively.

• Proceedings of the Korea Air Pollution Research Association Conference
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• 2001.11a
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• pp.165-166
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• 2001

HO$_2$ radical plays pivotal roles in the tropospheric $O_3$ formation chemistry. This radical oxidizes NO to NO$_2$ and thus HO$_2$ radical can lead to in-situ ozone formation. Numerous methods have been tried to measure concentrations of atmospheric HO$_2$ in gas phase. Detecting methods applied in the air are a chemical amplifier (Cantrell et al., 1996), FAGE (Fluorescence Assay with Gas Expansion) (Hard et al., 1984), and LIF (Laser-induced Fluorescence) (Stevens et al., 1994). These methods have been limited because of low sensitivity and interferences such as $O_3$, NO, and itself (Stevens et al.,1994). (omitted)

• Korean Journal of Medicinal Crop Science
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• v.13 no.5
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• pp.227-232
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• 2005

The antioxidant effect of methanol extract (ME) and water extract (WE) from Clematis trichotoma was evaluated as primary study to scavenge stable 1,1-diphenyl-2-picrylhydrazyl radicals (DPPH), inhibited iron-induce lipid peroxidation in linoleic acid emulsion, peroxidation of liposome induced by $Fe^{3+}/H_2O_2/ascorbie$ acid, and on $Fe^{2+}/H_2O_2$ induced the mitochondrial lipid peroxidation. In secondary study, five flavonoids as luteolin (1), quercetin (2), apigenin (3), hirsutrin (4), kaempferol-3-O-glucoside were isolated (5). Among them, compounds 1 and 2 showed good activities in all the model systems. Compound 3 exhibited moderate antioxidant activities in both radical scavenging and these lipid peroxidation systems tested. Compound 4 showed significant inhibitions in liposome peroxidation and compound 5 displayed weak inhibition in all four tested systems. All the results presented herein indicate that products of C. trichotoma maybe useful in inhibiting membrane lipid peroxidation and preventing free radical-linked diseases.

• Korean Journal of Pharmacognosy
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• v.47 no.2
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• pp.110-116
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• 2016

As a part of an ongoing search for natural plants with antioxidant compounds by measuring the radical scavenging effect on 1,1-diphenyl-2-picrylhydrazyl (DPPH), a total extract of the aerial parts of Bidens frondosa L. (Compositae) was found to show potent antioxidant activity. Subsequent activity-guided fractionation of the methanolic extract led to the isolation of five compounds, quercetin-3-O-${\beta}$-D-glucopyranoside (1), luteolin-7-O-${\beta}$-D-glucopyranoside (2), 7,8,3',4'-tertrahydroxy-flavanone (3), okanin-4-O-${\beta}$-D-glucopyranoside (4), and okanin (5). Their structures were elucidated by spectroscopic studies. Compounds 3-5 were isolated for the first time from this plant. Among them, compounds 3 and 5 showed the significant radical scavenging effects on DPPH, and compounds 3 and 5 also showed the potent riboflavin and xanthine originated superoxide quenching activities.

• Journal of Applied Biological Chemistry
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• v.63 no.4
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• pp.327-334
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• 2020

Oxidative stress is common cause of neurodegenerative diseases. The purpose of this study is to investigate the in vitro free radical scavenging activity and protective effect of three Glycyrrhiza species including Glycyrrhiza uralensis, G. glabra, and a new variety of Glycyrrihza (Shinwongam, SW) against hydrogen peroxide-induced oxidative stress in C6 glial cells. In vitro assays, radical scavenging activities of G. uralensis, G. glabra, and SW against 2,2-diphenyl-1-picrylhydrazyl, ·OH, and O2- increased as concentration-dependent manner. In addition, the SW was found to contain the highest polyphenol and flavonoid contents. The treatment of H2O2 to C6 glial cell induced oxidative stress, whereas G. uralensis, G. glabra, and SW significantly increased the cell viability as dose-dependent manner. In particular, SW exerted stronger protective effect on H2O2-induced cytotoxicity, than G. uralensis and G. glabra. Furthermore, reactive oxygen species (ROS) formation was significantly elevated by H2O2 in C6 glial cells. However, treatments of G. uralensis, G. glabra, and SW decreased ROS formation. In addition, SW decreased pro-inflammatory related protein expression levels such as inducible nitric oxide synthase and cyclooxygenase-2, compared to H2O2-treated control group. These results indicated that G. uralensis and G. glavra, especially SW, may be useful for preventing from oxidative stress-induced neuronal damage by regulating inflammatory reaction.

• Analytical Science and Technology
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• v.13 no.5
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• pp.652-658
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• 2000

Chemical degradation of aqueous humic acid by ozonation was studied with respect to the direct reactions of ozone and the indirect reactions due to its preliminary decomposition to secondary oxidant, OH radical. This was characterized by analyzing TOC, $UV_{254}$ and ozone consumption measured in different experimental conditions in which ozone reacted in the presence of various concentrations of $H_2O_2$ and $HCO_3{^-}$ concentrations ranging from 20 to 100 mg/L. and different pH (5-9). The results suggest that the TOC removal is mainly dependent on indirect reactions of OH radical whereas $UV_{254}$ reduction is mainly dependent on direct reactions of ozone with humic acid molecules. It has been also found that ozone consumption was most likely to be affected by pH and alkalinity in the solution.

• Food Science and Biotechnology
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• v.14 no.1
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• pp.58-63
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• 2005

Ethyl acetate-soluble neutral fraction of hot water extracts from the aerial parts of Angelica keiskei showed a 1, 1-diphenyl-2-picrylhydrazyl (DPPH) radical-scavenging activity. Six antioxidative compounds were purified and isolated by various chromatographic procedures. Based on the analyses of FAB-MS and NMR, the isolated compounds were structurally elucidated as luteolin 7-O-${\beta}$-D-glucopyranoside (1), quercetin 3-O-${\beta}$-D-galactopyranoside (2), quercetin 3-O-${\beta}$-D-glucopyranoside (3), quercetin 3-O-${\alpha}$-D-arabinopyranoside (4), kaempferol 3-O-${\alpha}$-D-arabinopyranoside (5), and luteolin 7-O-rutinoside (6). The glycosides of flavonols and luteolin showed DPPH radical-scavenging activity. One molecule of 2, 3, 4, 6, 1, and 5 scavenged 4.2, 4.2, 4.1, 2.5, 2.2, and 1.4 molecules of DPPH radical, respectively.

• ALGAE
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• v.28 no.4
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• pp.371-378
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• 2013

Water and methanolic extracts of Ecklonia cava, a marine brown alga, were prepared by ultrasonic extraction (UE) and conventional extraction (CE) methods. The radical-scavenging activity and the inhibitory effects against hydrogen peroxide ($H_2O_2$)-induced DNA damage of the extracts were investigated. All extracts prepared by CE exhibited higher total polyphenolic content than that in the extracts prepared by UE. Extraction yield and total phenolic content increased as the UE time increased. The radical-scavenging activities increased as the UE time increased. All extracts prepared by CE exhibited higher 1,1-diphenyl-2-pricrylhydrazyl (DPPH) and hydroxyl radical-scavenging activities than did those prepared by UE. Extracts prepared by UE showed stronger scavenging activities on alkyl radical and $H_2O_2$ than those prepared by CE did. Methanolic extract with UE 12 h (100MEU-12h) and methanolic extract with CE 24 h (100MEC-24h) were selected and evaluated by comet assay for their inhibitory effect against $H_2O_2$-induced DNA damage. 100MEU-12h showed slightly greater protective effect against $H_2O_2$-induced DNA damage than 100MEC-24h. Thus, UE can be effectively used as a seaweed extraction technique, and there is potential for scale-up of the extraction process.

• Journal of Ginseng Research
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• v.14 no.2
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• pp.191-199
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• 1990

It has been well known that extended exposure to reactive oxygens causes severe damage to susceptible biomolecules. In this study, the effects of flavonoids including trifolin and kaempferol from Ginseng leaves on singlet oxygen induced photohemolysis of erythrocytes and free radical scavenging activities were investigated. Each flavonoid aglycone (5-50$\mu$M) such as kaempferol, quercetin or baicalein exhibited a high protective effect against the photohemolysis. They protected the cells by scavenging $^1O_2$ and free radicals Although the free radical scavenging activities of the flavonoid glycosides were not much lower than those of their corresponding aglycones, their insolubility into lipid bilayers of membrane made them less effective in preventing the photohemolysis induced by $^1O_2$. The $^1O_2$ and free radical scavenging activities of flavonoids were estimated by the decomposition of the flavonoid by $^1O_2$ and the bleaching of free radicals by the flavonoid, respectively. The solubilization of the flavonoid into micells or erythrocytes was deduced from spectrophotometric and microscopic observations. The cooperation of L-ascorbic acid and a flavonoid, and a possible involvement of lipoxygenase or cyclooxygenase in the photohemolysis mechanism were discussed.

• Biomolecules & Therapeutics
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• v.19 no.3
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• pp.336-341
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• 2011

As part of an ongoing search for natural plants with antioxidant compounds by measuring the radical scavenging effect on 1,1-diphenyl- 2-picrylhydrazyl (DPPH), a total extract of the twigs of Galium spurium L. (Rubiaceae) was found to show potent antioxidant activity. Subsequent activity-guided fractionation of the methanolic extract led to the isolation of nine compounds, asperulosidic acid methyl ester (1), asperuloside (2), caffeic acid (3), kaempferol-3-O-L-rhamnopyranoside (4), quercetin-3-O-[${\alpha}$-Lrhamnopyranosyl($1{\rightarrow}6$)-${\beta}$-D-glucopyranoside] (5), isorhamnetin-3-O-glucopyranoside (6), quercetin-3-O-${\alpha}$-L-rhamnopyranoside (7), kaempferol-3-O-[${\alpha}$-L-rhamnopyranosyl($1{\rightarrow}6$)-${\beta}$-D-glucopyranoside] (8), and quercetin (9). Their structures were elucidated by spectroscopic studies. Compounds 1, 3-8 were isolated for the first time from this plant. Among them, compounds 3 and 9 showed the significant radical scavenging effects on DPPH, and compounds 3 and 7 showed the potent riboflavin originated superoxide quenching activities.