Objective To establish an indirect measurement of antioxidant activity of vegetables by UV-vis spectrophotometry. Methods Rhodamine 6G was oxidized by hydroxyl radical (·OH) produced by Fenton reaction and decolorized in dilute sulfuric acid medium. The change in absorbance could be determined at 520 nm, which was related to the amount of ·OH. If some antioxidants were added into this system, they could eliminate thc part of ·OH and further decrease the degree of decolorization of rhodamine 6G solution. Based on this principle, a new method was developed to determine the scavenging rate of ·OH. Results The optimal experimental condition of ·OH production was obtained through lots of experiments and the scavenging rates of ·OH with thiourea and benzoic acid were determined. Using this method, the antioxidant activity of some vegetables could be determined. Conclusion Tomato and cucumber have the best antioxidant activity.%目的 建立紫外-可见分光光度法间接测定蔬菜抗氧化活性的新方法.方法 在稀硫酸介质中,利用Fenton反应产生羟自由基,它可迅速氧化罗丹明6G溶液使其褪色,在520 nm波长处测吸光度A,A值与羟自由基的量有关,体系中加入抗氧化性物质可以清除部分羟自由基,使其氧化褪色体系溶液的程度减弱,由此建立了一种测定羟自由基清除率的新方法.结果 通过实验,找到产生羟自由基的最佳实验条件,并测定了硫脲、苯甲酸对羟自由基的清除率,利用该方法测定了几种蔬菜的抗氧化活性.结论 蕃茄、黄瓜的抗氧化活性最强.
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