• Applied Biological Chemistry
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• v.38 no.6
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• pp.590-595
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• 1995

To examine the characteristics of antioxidative compounds from Capsella bursa-pastoris, ethanol extracts were separated into five organic solvent fractions; hexane(Fr.H), diethyl ether (Fr.E), ethyl acetate(Fr.EA), butanol (Fr.B), and water(Fr.D) fractions. Fr.B showed the greatest electron donating ability and inhibitory effect on lipid peroxidation. Whereas Fr.E had the most excellent activity in the superoxide radical scavenging activity by xanthine/xanthine oxidase-cytochrome c reduction system. The inhibitory effect of each fraction on xanthine oxidase was also measured. Fr.E had the strongest inhibitory effect on xanthine oxidase and $IC_{50}$ was $5.65\;{\mu}g$. The results indicate that the superoxide radical scavenging activity of Fr.E is caused by the inhibitory effect on radical generating system of xanthine oxidase. Also the order of inhibitory effect on xanthine oxidase was Fr.B

• Food Science and Preservation
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• v.9 no.4
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• pp.369-374
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• 2002

This study was performed to investigate the effects of tyrosinase inhibition, xanthine oxidase inhibition and nitrite-scavenging effects of gamma-irradiated Schizandrae Fructus extracts from different solvents. Schizandrae Fructus was extracted by hot water, ethanol, acetone and methanol, and the extracts were irradiated 10, 20 and 30 kGy with gamma rays. All extracts from Schizandrae Fructus showed inhibition effect against tyrosinase. Tyrosinase inhibition effect of Schizandrae Fructus were higher in solvent extracts than hot water extracts by irradiation. The Schizandrae Fructus extracts had a higher inhibitory effect against xanthine oxidase, and the effect was not changed by irradiation. Nitrite scavenging activity, which was measured at various pH conditions (1.2, 3.0, 6.0), was the highest in Schizandrae Fructus extracts at pH 1.2 and 3.0. Hot water extracts provided higher nitrite scavenging effect than those of the methanol, ethanol and acetone extracts. Gamma-Irradiation may not influence on biological activites of the extracts when irradiated up to 30 kGy.

• Journal of the Korean Society of Food Science and Nutrition
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• v.27 no.4
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• pp.693-697
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• 1998

The influence of flavonols from onion skin on xanthine oxidase was investigated. Methanol extract was showed 12.8% of yield, 661.3mg% of flavonoids contents and 88.7% of inhibitory effect on xanthine oxidase F1 and F2 fractions were obtained from the methanol extract by ODS and Sephadex LH-20 chromatography. F1 and F2 fractions flavonols(3-OH free) identified by UV/visible spectroscopy. Inhibitory effect of F1 and F2 on xanthine oxidase were increased with increasing concentration. IC50s of F1 and F2 were 0.95$\mu\textrm{g}$ and 0.67$\mu\textrm{g}$, respectively. To confirm the specificity of F1 and F2 against xanthine oxidase, albumin was added to the reaction mixture. The inhibition of F1 and F2 may be due to specific binding to xanthine oxidase. The modes of their inhibitions were of mixed type with respect to xanthine as a substrate.

• Journal of the Korean Society of Food Science and Nutrition
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• v.24 no.1
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• pp.154-159
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• 1995

Inhibition of xanthine oxidase by tea extracts obtained from non-fermented tea(steamed green tea and roasted green tea), semi-fermented tea(oolong tea) and fermented tea(black tea) were investigated. The crude catechin fraciton had a hgher inhibitory effect against xanthine oxidase, and the effect was increased with the addition of tea extracts. Their inhibitory effect were hardly influenced until extracted three times with hot water. According to the investigation of catechins in the crude catechin fraction obtained from tea extracts, (-)-epicatechin-(EC), (-)-epicatechin gallate(ECg). (-)-epigallocatechin(EGC) and (-)-epigallocatechin gallate(EGCg) were 80.1$\mu\textrm{g}$/mg 113.5$\mu\textrm{g}$ /mg, 186.3$\mu\textrm{g}$/mg and 367.7$\mu\textrm{g}$/mg in steamed green tea, and 75.6$\mu\textrm{g}$/mg, 114.7$\mu\textrm{g}$/mg, 193.7 $\mu\textrm{g}$/mg and 381.9$\mu\textrm{g}$/mg in roasted green tea, and 69.4$\mu\textrm{g}$/mg, 110.0$\mu\textrm{g}$/mg, 127.1$\mu\textrm{g}$.mg and 464.9$\mu\textrm{g}$/mg in oolong tea, and 78.1$\mu\textrm{g}$/mg, 171.8$\mu\textrm{g}$/mg, 80.7$\mu\textrm{g}$/mg and 51.4$\mu\textrm{g}$/mg in black tea, respectively. Order of the content of these catechins was (-)-EGCg>(-)-EGC>(-)-ECg>(-)-EC in steamed green tea, roasted green tea and oolong tea, and was (-)-ECg>(-)-EGC>(-)-EC>(-)-EGCg in black tea. Also the concentration of catechins was hardly influeced until extracted three times. The inhibition ratio of xanthine oxidase by autherntic catechins was hardly influenced until extracted three times. The inhibition ratio of xanthine oxidase by authentic catechins was 94.9% and 87.6% by addition of 5.0$\mu\textrm{g}$/ml of (-)-EGCg and (-)-ECg, respectively. the inhibitors of xanthine oxidase were supposed to be due to (-)-ECg and (-)-EGCg in tea polyphenol compounds.

• Journal of the Korean Society of Food Science and Nutrition
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• v.22 no.4
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• pp.418-422
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• 1993

For the purpose of utilizing tannins in the functional foods and crude drugs the xanthine oxidase inhibition of tannins isolated from Korean green tea was determined. Acetone extract from Korean green tea showed inhibitory effect against the xanthine oxidase. The galloyl tannins showed higher inhibitory activity against xanthine oxidase than the nongalloyl tannins. In terms of stereo isomers, (-)-epicatechins had higher inhibitory activity than the (+)-catechins. The synergistic activity was also observed. Tannins isolated from Korean green tea appeared to be incompetitive inhibitor against the xanthine oxidase.

• The Korean Journal of Food And Nutrition
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• v.14 no.2
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• pp.120-125
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• 2001

The inhibitory effects of xanthine oxidase by the methanol extract and the solvent fractions obtained from persimmon leaves were investigated. The inhibition ratio of xanthine oxidase was 78% by addition of 2.0mg/ml of the methanol extract. Among the solvent fractions, the ethylacetate fraction showed the strongest inhibitory effect against the xanthine oxidase, followed by the hexane fraction. The effect increased with addition of the ethylacetate fraction. At a concentration of 2.0mg/ml of the ethylacetate fraction, 65% of the enzyme activity decreased within 1.0 min of incubation with xanthine oxidase. But the activity of xanthine oxidise did not decrease significantly by the length of the incubation time.

• Korean Journal of Food Science and Technology
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• v.24 no.6
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• pp.558-562
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• 1992

Xanthine oxidase involved in pruine metabolism oxidizes hypoxanthine to xanthine and xanthine to uric acid. The derangement of pruine metabolism results in gout that associates painful deposit of monosodium urate in the cartilage of joints. In the continuous study for natural compound, six flavan-3-ols have been isolated from the leaves of Oolong tea. The structures of procyanidin B-1, B-3, procyanidin B-3-3-O-rhamnose, procyanidin B-1-3-O-gallate, (-)-epicatechin, (-)-epicatechin-3-O-gallate were established by NMR and their inhibitory effect on xanthine oxidase activity was investigated. Flavan-3-ols containing the gallate had a high inhibitory capacity. Procyanidin B-1-3-O-gallate showed complete inhibition at $50\;{\mu}M$ and inhibited on the xanthine oxidase competitively.

• Preventive Nutrition and Food Science
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• v.8 no.1
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• pp.85-88
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• 2003

Effects of irradiation on color removal, tyrosinase inhibition, xanthine oxidase inhibition and nitrite scavenging capacity of Lonicera japonica extracts were evaluated. Lonicera japonica extracts were irradiated at 10, 20, and 30 kGy. Hunter color $L^{*}$- and $a^{*}$-values increased but $b^{*}$-values decreased dose-dependently following irradiation. The extracts were potent inhibitors of tyrosinase and xanthine oxidase. Tyrosinase inhibition was higher in the irradiated sample than non-irradiated, and subsequently increased with increasing irradiation doses. The extracts had a higher inhibitory effect against xanthine oxidase, and the effect was not changed by irradiation. Nitrite scavenging capacity was the highest in the extract at pH 1.2, and was not significantly affected by irradiation. These results indicate that gamma irradiation may not influence the biological activities of Lonicera japonica extracts when irradiated up to 30 kGy. Furthermore, color of the extracts can be improved to have improved applicability for the food and cosmetic industries without any adverse change in biological functions.ons.s.

• Korean Journal of Medicinal Crop Science
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• v.11 no.1
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• pp.31-39
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• 2003

The antioxidative activities and biological properties in the EtOAc extracts and purified extracts of Orostachys japonicus were measured by assay of DPPH, xanthine/xanthine oxidase and mammalian cells(2-12). Scavenging of DPPH radical and inhibition of xanthine/xanthine oxidase of EtOAc extracts were showed the highest activity in the arable land and in September. The S-4 fraction showed the highest activity among the silica-gel column chromatography fractions. LH-4 fraction showed higher activity than the other fractionsins in assay of DPPH and xanthine/xanthine oxidase. Fatty acids and phenolic compounds were identified by GC/MS and main compounds were 1,2,3-benzenetriol, alpha-androsta-7,14-diene in LH-4 fraction. The activities of POD and SOD in samples havested on different habitats were high such as arable land> intermountain> seashore. That of POD and SOD in crude extracts of late stage were higher than early stage. Isozyme bands of crude extracts samplinged in all habitats and all growing stages showed two bands and the signal intensity showed strongly according to passage of growing stage. The purified extracts of LH-4 fraction showed excellent inhibition effect in proliferation of HL-60 cells and markedly suppressed colony formation in mouse fibroblast cells. Dose response between partially purified extracts(400ppm) and negative control did not produced statistically significant reduction in colony formation.

• Applied Biological Chemistry
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• v.40 no.3
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• pp.254-258
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• 1997

To examine the characteristics of the antioxidative property of Buckwheat components, acetone extracts from a buckwheat, Suwon 5, was fractionated using five solvents. Hexane, ethylacetate, ether, butanol and water fractions were obtained. Butanol fraction showed the greatest electron donating ability and inhibitory effect on lipid peroxidation. It also showed the most excellent activity in the superoxide radical scavenging activity by xanthine/xanthine oxidase-cytochrome c reduction system. Spectrophotogram of butanol fraction was similar to that of rutin. Superoxide radical scavenging activity was related to the contents of rutin. Inhibitory effect of each fraction on xanthine oxidase was also measured. Butanol fraction had the strongest inhibitory effect on xanthine oxidase and $IC_{50}\;was\;3.1\;{\mu}g$. The inhibition type of butanol fraction on xanthine oxidase turned out to be a mixture of the uncompetitive and non-competitive modes.