没食子酰基金丝桃甙的抗氧化性及其构效关系研究

目的　通过对没食子酰基金丝桃甙 (Gq)清除氧自由基作用的测定 ,探讨Gq的抗氧化性并对其抗氧化机理与结构之间的关系进行探讨。方法　分别采用黄嘌呤 黄嘌呤氧化酶体系及Fenton反应体系 ,测定Gq对超氧阴离子自由基 (SAFR)和羟基自由基 (HFR)的清除作用 ,得出清除率与浓度之间的相关关系 ,求出IC50 值 ,以表示其抗氧化能力。对比分析Gq及天然抗氧剂槲皮素和芦丁的化学结构 ,探讨抗氧化机理与结构之间的构效关系。 结果　Gq对氧自由基具有明显的清除活性 ,清除SAFR和HFR的IC50 值分别为 4 0 .8μmol·L-1和 33.5 μmol·L-1,远小于阳性对照物槲皮素 (分别为 114 .0 μmol·L-1和 10 0 .8μmol·L-1)及芦丁 (15 2 .0 μmol·L-1和 91.4 μmol·L-1)。结论　Gq具有明显的抗氧化性 ,其抗氧化活性与其分子结构中多元酚结构有关 ,但其抗氧化机理不同于小分子的没食子酰类衍生物

The antioxidativity of 2′-O-galloyl-3-β-galactosyloxy quercetin and the structure-activity relationships

Objective To study the antioxidativity of 2′-O-galloyl-3-β-galactosyloxy quercetin (Gq) and to investigate the relationship between the antioxidative mechanism and its structural characteristics. Methods The scavenging effects for superoxide anion and hydroxy free radical of Gq were measured in the xanthine-xanthine oxidase system and Fenton reaction system, respectively. The antioxidativity was shown by IC 50 value, which was determined by the regression lines. The antioxidative mechanism of Gq was explored by analysing its structural characteristics and comparing them with those of quercetin and rutin. Results Gq exhibited obvious scavengeing effects for oxygen free radicals, the value of IC 50(40.8 μmol·L -1 and 35.1 μmol·L -1)was much less than that of quercetin(114.0 μmol·L -1 and 95.7 μmol·L -1)and rutin(152.0 μmol·L -1 and 120.9 μmol·L -1). Conclusion Gq shows strong antioxidativity. This property may come from its polyphenol structure, but the mechanism may be different from that of some small molecule galloyl ester derivatives.