• Archives of Pharmacal Research
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• 제26권6호
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• pp.458-462
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• 2003

The antioxidant activity of the stem bark from Albizzia julibrissin was evaluated for its potential to scavenge 1,1-diphenyl-2-picrylhydrazyl (DPPH) radicals, to inhibit the generation of the hydroxyl radical ($\cdot OH$), total reactive oxygen species (ROS) and to scavenge authentic peroxynitrites ($ONOO^{-}$). The methanol extract of A. julibrissin exhibited strong antioxidant activity in the tested model systems. Therefore, it was further fractionated using several solvents. The antioxidant activity of the individual fractions were in the order of ethyl acetate (EtOAc) ＞ n-butanol (n-BuOH) ＞ dichloromethane ($CH_2 CI-2$) ＞ and water ($H_2O$). The ethyl acetate soluble fraction, which exhibited strong antioxidant activity, was further purified by repeated silicagel, Sephadex LH-20 and RP-18 gel column chromatography. Sulfuretin (1) and 3 ,4 ,7-trihydroxyflavone (2) were isolated as the active principles. Compounds 1 and 2 exhibited good activity in all tested model systems. Compound 1 exhibited five times more inhibitory activity on the total ROS than Trolox. Compound 2 showed six times stronger DPPH radical scavenging activity than L-ascorbic acid. These results show the possible antioxidant activity of the A. julibrissin crude extract and its major constituents.

• Journal of Microbiology
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• 제45권3호
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• pp.262-267
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• 2007

During a screening program, an actinomycete strain isolated from the Egyptian soil was investigated for its potential to show antimicrobial activity. The identification of this isolate was performed according to spore morphology and cell wall chemo-type, which suggested that this strain is a streptomycete. Further cultural, physiological characteristics and the analysis of the nucleotide sequence of the 16S rRNA gene (1480 bp) of this isolate indicated that this strain is identical to Streptomyces violaceusniger (accession number EF063682) and then designated S. violaceusniger strain HAL64. In its culture supernatant, this organism could produce one major compound strongly inhibits the growth of Gram-positive but the inhibition of Gram-negative indicator bacteria was lower. The antibiotic was separated by silica gel column chromatography and then purified on a sephadex LH-20 column and finally the purity was checked by HPLC. The chemical structure of the purified compound was determined using spectroscopic analyses (molecular formula of $C_{33}H_{32}N_{2}O_{10}$ and molecular weight of 617.21) and found to be identical to the kosinostatin, a quinocycline antibiotic which is known to be produced by Micromonspora sp. TP-A0468 (Igarashi et al., 2002) and to quinocycline B isolated from Streptomyces aureofaciens (Celmer et al., 1958). Although the antibiotic is known, the newly isolated strain was able to produce the antibiotic as a major product providing an important biotechnological downstream advantage.

• Applied Biological Chemistry
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• 제47권2호
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• pp.279-282
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• 2004

An antioxidant was isolated from Korean mistletoe (Viscum album var. coloratum) by consecutive purification using silica gel, Sephadex LH-20, and RP-HPLC. The active principle was identified as homo-flavoyadorinin-B (3',7-dimethoxyluteolin-4'-O-[apiosyl $(1{\rightarrow}2)$ glucoside]) by spectral analyses. It inhibited 74.6% of hydroxyl radical and 30.6% of superoxide anion radical at 0.01 mM; however, th~compound did not show any scavenging activity against hydrogen peroxide radical. At 0.1 mM, above compound scavenged superoxide anion radical about twice as effective as positive controls, BHT and ${\alpha}-tocopherol$. Radical scavenging activities of homo-flavoyadorinin-B on DPPH, hydroxyl, and hydrogen peroxide radicals were almost same with those of positive controls.

• Natural Product Sciences
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• 제22권1호
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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.

• 생약학회지
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• 제42권3호
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• pp.223-228
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• 2011

Chaenomeles sinensis Koehne (Rosaceae) is a deciduous tree and is distributed in China, Korea and Japan. In previous studies on the fruits of C. sinensis, some triterpenoid compouds such as oleanolic acid, tormentic acid were reported. In an ongoing investigation into biologically active compounds from natural products, the methanol extract of the stems of C. sinensis was investigated. By means of the repeated column chromatography using silica gel, Sephadex LH-20, LiChroprep RP-18, betulin (1), tormentic acid (2), 1-${\beta}$-D-glucopyranosyl-3,4,5-trimethoxybenzene (3), lyoniresinol-2a-O-${\alpha}$-L-rhamnopyranoside (4) were isolated. The chemical structures of compounds 1-4 were determined by the basis of physico-chemical properties and spectroscopic methods such as 1D and 2D NMR. For the isolated compounds (1-4), the inhibitory activity of IL-6 production in TNF-${\alpha}$ stimulated MG-63 cell was examined. Among the isolates, betulin (1), 1-${\beta}$-D-glucopyranosyl-3,4,5-trimethoxybenzene (3), lyoniresinol-2a-O-${\alpha}$-L-rhamnopyranoside (4) showed inhibitory effects on IL-6 production in TNF-${\alpha}$ stimulated MG-63 cell.

• 생약학회지
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• 제41권3호
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• pp.180-184
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• 2010

The antioxidant activity of Desmodium oldhami (Leguminosae) was determined by measuring the radical scavenging effect on DPPH (1,1-diphenyl-2-picrylhydrazyl). The methanolic extract of D. oldhami showed the strong antioxidant activity. Five compounds, kaempferol-3-O-rhamnopyranoside (afzeline) (1), quercetin-3-O-[$\alpha$-L-rhamnopyranosyl($1{\rightarrow}6$)-$\beta$-Dglucopyranoside] (rutin) (2), kaempferol-3-O-glucopyranoside (astragalin) (3), genistein-7-O-$\beta$-D-glucopyranoside (genistin) (4), kaempferol-3-O-rutinoside (5) were isolated from the active ethyl acetate soluble fraction of D. oldhami through repeated silica gel and Sephadex LH-20 column chromatography. Among them, compound 2 showed the most significant antioxidative effect on DPPH free radical scavenging test. Compounds 1-5 are reported for the first time from this plant.

• Journal of the Korean Wood Science and Technology
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• 제43권2호
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• pp.214-223
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• 2015

The bark of Acer komarovii was collected, ground, and extracted with 70% aqueous acetone to obtain concentrates. The concentrates were suspended in $H_2O$, and then successively partitioned with n-hexane, dichloromethane and ethylacetate to be freeze dried. A portion of ethylacetate fraction was chromatographed on a Sephadex LH-20 and a RP C-18 column with various aqueous MeOH-$H_2O$ (1:0, 1:1, 1:2, 1:5, 1:7, 1:9, 1:10, 3:1, and 4:1, v/v) eluents. Four compounds were isolated; (-)-epicatechin (9.6 g), procyanidin A2 (epicatechin-($4{\beta}{\rightarrow}8$, $2{\beta}{\rightarrow}O{\rightarrow}7$)-epicatechin) (1.3 g), procyanidin B2 (epicatechin-($4{\beta}{\rightarrow}8$)-epicatechin) (40.0 mg), and cinnamtannin B1 (epicatechin-($4{\beta}{\rightarrow}8$, $2{\beta}{\rightarrow}O{\rightarrow}7$)-epicatechin-($4{\beta}{\rightarrow}8$)-epicatechin) (690 mg). The analysis of the bark procyanidins showed that the basic unit constituting condensed tannins was only (-)-epicatechin. This study, for the first time, report the procyanidins of Acer komarovii bark.

• 생약학회지
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• 제24권4호
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• pp.299-303
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• 1993

The antioxidant activity of methanol extracts of plants and marine algae was tested by using 1,1-diphenyl-2-picrylhydrazyl(DPPH). Five plant extracts(Prunus davidiana, Eriobotrya japonica, Artemisia iwayomogi, Stirodella tolyrrhiza and Ulmus davidiana) and two algae (Ecklonia stolonifera and Symphycoladia latiuscula) were found to be the most effective in DPPH radical scavenging activity. The methanol extract obtained from the stems of Prunus davidiana was fractionated with several solvents. The ethylacetate soluble fraction exhibiting the strongest antioxidant activity was further purified by repeated silica gel and Sephadex LH-20 column chromatography. Antioxidant flavonoids and flavonoid glycosides were isolated and the most active ones was identified as (+)-catechin by MS, $^1H-NMR$ and $^{13}C-NMR$. Its antioxidant activity was higher than that oil vitamin C.

• Food Science and Biotechnology
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• 제15권3호
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• pp.424-430
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• 2006

Low molecular weight polyphenols were isolated from hot water extracts of radiata pine (Pinus radiata) bark using a Sephadex LH-20 column and characterized by $^1H$ and $^{13}C$ NMR, UV, FT-IR, and GC-MS analyses. Major compounds isolated and identified were protocatechuic acid, trans-taxifolin, and quercetin. Trans-taxifolin, an important intermediate in biosynthetic route of proanthocyanidin (PA), was isolated in large quantities and indicates that PA is a major component of radiata pine bark. Small amounts of polyphenols were identified by GC-MS analysis. The presence of p-hydroxybenzoic acid, vanillic acid, protocatechuic acid, cis- and trans-feruic acid, p-coumaric acid, trans-caffeic acid, (-)-epicatechin, (+)-catechin, trans- and cis-taxifolin, (+)-gallocatechin, and quercetin was confirmed by comparison of mass fragmentation patterns and retention times (RT) with authentic samples. In addition, the presence of astringenin, astringenin glycoside, trans- and cis-leucodelphinidin was strongly assumed from characteristic mass fragment ions due to their conjugated structure and retro Diels-Alder reaction, and also from biosynthetic route of PA. GC-MS analysis allowed us to detect small amounts of phenolic acids and flavonoids and eventually discriminate trans- and cis-configuration in the identified polyphenols.

• Preventive Nutrition and Food Science
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• 제2권3호
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• pp.191-196
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• 1997

The antioxidative activity of seven different acylated anthocyanin pigments isolated from grape, sweet potato, eggplant and red cabbage was evaluated bvy using linoleic acid autoxidation and rat liver microsomal systems. The acylated anthocyanins were isolated and purified by Amberlite SAD-7, ODS and Sephadex LH-20 column omatography, and preparative HPLC. Most of acylated anthocyanisns exhibited antioxidative activity as strong as $\alpha$-tocoperol, and especially peonidin3-O--(6-O-trans-caffeyl)-2-O-(6-O-trans-feuloylglucopyranosyl)-$\beta$-D-glucopyranosyl-5-O-$\beta$-D-glucopyranoside from purple sweet potato showed the strongest activity, comparable to BHA (not significant, p<0.05) in the linoleic acid system. Meanwhile, two acylated anthocyanins from the pericarps of grape and eggplant inhibited considerably the MDA formation from rat liver microsomal lipid peroxidation induced by FeSO$_4$/$H_2O$$_2$. In particular, malvidin 3-O-(6-O-p-coumaroyl)-$\beta$-D-glucopyranosde from grape pericarps showed the strongest antioxidant activity, comparable to $\alpha$-tocopherol (not significant, p<0.05). These results suggest that the acylated anthocyanins from fruits and vegetables can be used as potential dietary ntioxidants and natural colorants.