罗丹明6G-Co^(2+)-KI-H_2O_2光度法测定抗氧化剂清除羟自由基的能力

Determination of hydroxyl free radical scavenging activities of antioxidants by photometric method based on Rh6G-Co^(2+)-KI-H_2O_2 system.

建立了一种基于罗丹明6G(Rh6G)-Co2+-KI-H2O2反应体系的检测抗氧化剂清除羟自由基能力的光度分析新方法。在HAc-NaAc缓冲溶液中,Co2+与H2O2反应,产生的羟自由基与过量的KI反应,生成的Iˉ3与Rh6G络合,使体系的吸光度值降低,根据ΔA527值的变化可间接测得羟自由基的生成量。抗氧化剂的加入可抑制吸光度值降低,从而间接测定其清除羟自由基的能力。考察了抗坏血酸、硫脲、没食子酸等几种常见抗氧化剂清除羟自由基的能力,结果为:没食子酸>硫脲>抗坏血酸。比较了Mn2+,Co2+,Fe2+离子与H2O2反应时羟自由基的产生量。测定了几种蔬菜和水果的羟自由基清除能力,结果表明,苹果和芹菜具有较高的羟自由基清除效率。

A new method is developed for the determination of hydroxyl free radical scavenging activities of antioxidants by spectrophotometry, based On Rh6G-Co^2＋ -KI-H2O2 system. In HAc -NaAc buffer solution, the hydroxyl free radicals generated by the reaction of Co^2＋ and H2O2 react with excessive KI to yield I3, and then I3 complexes with Gh6G, resulting in the decrease of absorbance of the system at the maximum absorption wavelength （527nm）. But the decrease of absorbance can be suppressed in the presence of antioxidant. According to the change of absorbance （ AA 527）, the amount of hydroxyl free radicals generated and the scavenging activity of antioxidant can be measured indirectly. The scavenging activities of several common antioxidants are investigated,and the result is L-ascorbic acid〉fulfourea〉gallic acid. The hydroxyl free radicals generating ability of Mn^2＋ , Co^2＋, and Fe^2＋ reacted with H2O2 are compared. The hydroxyl free radical scavenging activities of several vegetables and fruits are determined. The results show that apple and celery have higher scavenging activity.