化学
苷元
DPPH
激进的
黄嘌呤氧化酶
糖苷
类黄酮
脱氧核糖
超氧化物
抗氧化剂
药物化学
光化学
有机化学
生物化学
酶
DNA
作者
Beena Mishra,K. Indira Priyadarsini,Manoj Kumar,M.K. Unnikrishnan,Hari Mohan
标识
DOI:10.1016/s0968-0896(03)00232-3
摘要
Chrysoeriol and its glycoside (chrysoeriol-6-O-acetyl-4′-β-d-glucoside) are two natural flavonoids extracted from the tropical plant Coronopus didymus. The aqueous solutions of both the flavonoids were tested for their ability to inhibit lipid peroxidation induced by γ-radiation, Fe (III) and Fe (II). In all these assays chrysoeriol showed better protecting effect than the glycoside. The compounds were also found to inhibit enzymatically produced superoxide anion by xanthine/xanthine oxidase system; here the glycoside is more effective than the aglycone. The rate constants for the reaction of the compounds with superoxide anion determined by using stopped-flow spectrometer were found to be nearly same. Chrysoeriol glycoside reacts with DPPH radicals at millimolar concentration, but the aglycone showed no reaction. Using nanosecond pulse radiolysis technique, reactions of these compounds with hydroxyl, azide, haloperoxyl radicals and hydrated electron were studied. The bimolecular rate constants for these reactions and the transient spectra of the one-electron oxidized species indicated that the site of oxidation for the two compounds is different. Reaction of hydrated electron with the two compounds was carried out at pH 7, where similar reactivity was observed with both the compounds. Based on all these studies it is concluded that chrysoeriol exhibits potent antioxidant activity. O-glycosylation of chrysoeriol decreases its ability to inhibit lipid peroxidation and reaction with peroxyl radicals. However the glycoside is a more efficient scavenger of DPPH radicals and a better inhibitor of xanthine/xanthine oxidase than the aglycone.
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