儿茶素抗氧化作用的协同增效效应

用电子自旋共振(ESR)和化学发光技术,研究了(-)-EGCG、(-)-ECG、(-)-EC、(-)-EGC 4种儿茶素及其不同组合,对超氧阴离子自由基(O(?))的清除作用。结果表明,单一儿茶素以(-)-EGCG 的清除能力最强,其纳摩尔清除率为316.3,其次为(-)-ECG,纳摩尔清除率为262.9;两两不同组合对O(?)的清除率以(-)-EGCG+(-)-ECG 效果最佳,比各自单独存在时要增效,三三组合时以(-)-EGCG+(-)-ECG+(-)-EC 组合效果最佳,增效效果明显,且强于两两组合。这些组合的增效效果与体系中存在的儿茶素的摩尔浓度呈高度的线性正相关。4种儿茶素组成不同的比例,以茶叶天然组成增效效果最明显。用伏安法测得的各儿茶素第一还原电位由高到低的次序为:(-)-EGCG>(-)-ECG>(-)-EGC≈(-)-EC,这一电位次序是儿茶素构成抗氧化循环的根本所在。

Coordinatingly Synergic Effect of Catechins During Their Antioxidation

The scavenging effects of catechins on superoxide anion free radical(O(?))and their coordinatingly synergic effects were studied by using electronspin-trapping resonance(ESR)technique and chemilluminescence(CL)methodin Xanthine-Xanthine Oxidase system.Resuts showed that the scavengingeffect of(-)-EGCG was the best and its scavenging percentage was 316.3per nmol.(-)-EGCG+(-)-ECG was the most effective among the 2-catechincombination and was stronger than one catechin.(-)-EGCG+(-)-ECG+(-)-EC was the most effective among the 3-catechin combination and wasstronger than 2-catechin combination.The synergic effect was positivelycorrelated to the molecular concentrations of the catechins.The naturalcatechin combination in tea leaves possessed the strongest antioxidativeeffect.Using V-A method,the first reducing potentials of catechins werelisted as(-)-EGCG>(-)-ECG>(-)-EC or(-).EGC,and this is the foun-dation of the antioxidative recycling of the catechins.