• Biomolecules & Therapeutics
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• v.18 no.2
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• pp.191-196
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• 2010

In the course of screening for antioxidant compounds by measuring the radical scavenging effect on 1,1-diphenyl- 2-picrylhydrazyl (DPPH), a total extract of the twigs of Stewartia koreana (Theaceae) was found to show potent antioxidant activity. Subsequent activity-guided fractionation of the methanolic extract led to the isolation of six phenolic compounds, ampelopsin (1), catechin (2), proanthocyanidin-A2 (3), fraxin (4), (2R, 3R)-taxifolin-3-${\beta}$-D-glucopyranoside (5), and (2S, 3S)-taxifolin-3-${\beta}$-D-glucopyranoside (6), as active principles. Their structures were elucidated by spectroscopic studies. Compounds 1-6 were isolated for the first time from this plant. Among them, three compounds 1-3 showed the significant antioxidative effects on DPPH, and riboflavin originated superoxide quenching activity. In riboflavin-nitrobluetetrazolium (NBT)-light system, compound 1 showed better superoxide quenching activity than vitamin C.

• Korean Journal of Pharmacognosy
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• v.33 no.4 s.131
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• pp.404-410
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• 2002

Phytochemical examination of Barks of Ulmus macrocarpa has led to the isolation and characterization of two fla-vanonol, taxifolin $7-O-{\beta}-D-glucopyranoside$ (1), taxifolin $3'-0-7-{\beta}-glucopyranoside$ (2), two flavanone eriodictyol $7-O-{\beta}-D-glucopyranoside$ (3), nalingenin $7-O-{\beta}-D-glucopyranoside$ (4), three flavan 3-ol, (+)-catechin (5), (-)-epicatechin (6), (+)-catechin 7-O-{\beta}-D-glucopyranoside (7) and one proanthocyanidin, procyanidin B-1 (8). Antioxidative activity of these compounds was determined by measuring the radical scavenging effect on 1,1-diphenyl-2- picrylhydrazyl (DPPH) radicals . (+)-Catechin (5) , (-)-epicatechin (6), (+)-catechin $7-O-{\beta}-D-glucopyranoside$ (7) and procyanidin B-1 (8) showed significant antioxidative activity.

• Natural Product Sciences
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• v.11 no.2
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• pp.97-102
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• 2005

From the n-BuOH soluble traction of the 70% aqueous acetone extract of Rhododendron mucronulatum stem, twelve compounds were isolated. On the basis of spectral data, they were identified as scopoletin (1), (+)-taxifolin (2), quercetin (3), (-)-catechin (4), (+)-epicatechin (5), scopolin (6), lyoniside (7), ssioriside (8), fraxin (9), $(+)-lyoniresinol-3{\alpha}-O-{\beta}-D-glucopyranoside$ (10), $(+)-taxifolin-3-O-{\alpha}-L-arabinopyranoside$ (11), and astragalin (12), respectively. All isolated compounds were tested antioxidant activity against 1, 1-diphenyl-2-picrylhydrazyl (DPPH) radical. Compounds 2 and 3 showed the potent antioxidant activity, and compounds 5, 8, and 11 showed moderate activity.

• Korean Journal of Pharmacognosy
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• v.29 no.3
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• pp.163-168
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• 1998

Seven antioxidative compounds were isolated from chloroform and ethyl acetate extracts of the stem bark of Eucalyptus globulus (Myrtaceae). They were identified as rhamnazin (1), rhamnetin (2), naringenin (3), eriodictyol (4), quercetin (5), taxifolin (6) and dihydrokaempferol-3-rhamnoside (7) on the basis of various spectroscopic analyses. These compounds inhibited lipid peroxidation with $IC_{50}$ values of 0.08-30 ${\mu}g/ml$.

• Archives of Pharmacal Research
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• v.25 no.4
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• pp.441-445
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• 2002

Three naphthalene glycosides (1-3), four flavonoids (4-7), and two galloyl glycosides (8-9) were isolated from the stem-bark of Juglans mandshurica (Juglandaceae). Their structures were determined by chemical and spectral means, including to 2D-NMR (COSY, HMQC, and HMBC) experiments. Amongst the isolated compounds, taxifolin (4) showed the most potent HIV-induced cytopethic activity against MT-4 cells with complete inhibitory concentration ($IC_{100}$) value of $25{\;}{\mu\textrm{g}}/ml$ and maximum cytotoxic concentration ($CC_{100}$) value of above $100{\;}{\mu\textrm{g}}/ml$. However, naphthalene glycosides (1-3), flavonoids (5-7)), and galloyl tannins (8-9) were inactive against anti-HIV-1 activity.

• Archives of Pharmacal Research
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• v.25 no.4
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• pp.449-452
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• 2002

The antioxidant activity of Juniperus chinensis (Cupressaceae) was determined by measuring the radical scavenging effect on DPPH (1,1-diphenyl-2-picrylhydrazyl). The methanolic extract of J. chinensis heartwood showed the strong antioxidant activity. The antioxidant activity of n-BuOH soluble fraction was stronger than that of the others, and the fraction was subjected to purification by repeated silica gel and Sephadex LH-20 column chromatography. Quercetin, naringenin, taxifolin, aromadendrin and isoquercitrin were isolated from the n-BuOH fraction. Their structures were elucidated by physico-chemical and spectroscopic studies.

• Journal of the Korean Wood Science and Technology
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• v.34 no.4
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• pp.76-82
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• 2006

The dried ground needles (2.0 kg) of Chamaecyparis pisifera (Sieb. et Zucc.) Endlicher were extracted with acetone-$H_2O$ (7:3, v/v), concentrated, and fractionated with a series of n-hexane, methylene chloride, ethyl acetate and water on a separation funnel. Each fraction was freeze dried, then a portion of ethyl acetate soluble powder was chromatographed on a Sephadex LH-20 column using a series of aqueous methanol and ethanol-n-hexane mixture as eluents. The isolated compounds were identified by cellulose TLC, $^1H$-, $^{13}C$-NMR, COSY, HETCOR, FAB and EI-MS. (+)-catechin, taxifolin-3-O-${\beta}$-D-xylopyrano-side, quercetin-3-O-${\alpha}$-L-rhamnopyranoside were isolated from the ethyl acetate soluble fraction of Chamaecypairs pisifera needle. Antioxidative tests on the isolated compounds indicated that all of the compounds showed similar values to ${\alpha}$-tocopherol and BHT as controls.

• Journal of Forest and Environmental Science
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• v.18 no.1
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• pp.53-60
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• 2001

2kg of the dried leaves of chamaecyparis obtusa Endlicher were ground, extracted with acetone-$H_2O$(7:3, v/v), concentrated, and fractionated with a series of hexane, $CH_2Cl_2$, EtOAc and water on a separatory funnel. Each fraction was freeze dried to give dark-brown powder and a EtOAc soluble portion of the powder was chromatographed on a Sephadex LH-20 column using a series of aqueous methanol and ethanol-hexane mixture as eluents. Spectrometric analyses such as NMR and FAB-MS including TLC were performed to characterize the structures of the isolated compounds. The leaves of chamaecyparis obtusa Endlicher contained a large amount of taxifolin-3-O-${\beta}$-D-xylopyranoside and (+)-catechin in addition to a small amount of quercetin-3-O-${\alpha}$-L-rhamnopyranoside.

• Journal of the Korean Society of Food Science and Nutrition
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• v.39 no.8
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• pp.1132-1136
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• 2010

After Cheonnyuncho (Opuntia humifusa) was extracted by 70% ethanol and partitioned with hexane, chloroform, ethyl acetate, butanol, and water in order, ethyl acetate fraction with excellent antioxidant activities was acquired. Ethyl acetate fraction was conducted by TLC, and the third spot of 10 spots was selected due to its best antioxidant activities. When the third fraction further isolated on silica gel chromatography, the fourth fraction of 10 fractions had the best antioxidant activities and purified by HPLC. The molecular weight on EI-MS, and $^1H$- and $^{13}C$-NMR spectrum showed that the purified compound was taxifolin. In addition, antioxidant activities were analyzed, and the purified compound from Cheonnyuncho was found to be effective as much as $\alpha$-tocopherol, BHA. According to the analysis on antibacterial activities, the purified compound also showed more activity than benzoic acid against all pathogenic bacteria.

• Food Science and Biotechnology
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• v.16 no.1
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• pp.116-122
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• 2007

Four compounds with antioxidant activity were isolated from the MeOH extract of peanut shells (pod) and identified as 5,7-dihydroxychromone (1), eriodictyol (2), 3',4',7-trihydroxyflavanone (3), and luteolin (4) by electron impact-mass spectrometry (EI-MS) and nuclear magnetic resonance (NMR) analyses. The relationship between antioxidant activity and chemical structure of the isolated compounds with their analogues [(-)-epicatechin, quercetin, taxifolin] was examined by measuring 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical-scavenging activity and using the 2-deoxy-D-ribose degradation system. The order of antioxidant activity on the basis of DPPH radical-scavenging was quercetin = (-)-epicatechin (6.0 molecules) > taxifolin (4,5 molecules) > 4 (luteolin; 4.0 molecules) > 2 (eriodictyol; 2.5 molecules) > 3 (3',4',7-trihydroxy-flavanone; 2.0 molecules) > 1 (5,7-dihydroxychromone; 0.5 molecules). On the other hand, using the 2-deoxy-D-ribose degradation system, the order of antioxidant activity was quercetin > 4 >> (-)-epicatechin ${\geq}\;2\;{\geq}$ taxifolin > 3 > 1. These compounds from peanut shells may provide defensive measures against oxidative stress and insects in the soil.