荧光分光光度法测定两种中药对羟基自由基的清除作用

Fe2 EDTA在弱碱性介质中还原溶解氧生成超氧阴离子自由基(O 2·),O 2·进一步歧化为H2O2和氧分子,之后Fe2 EDTA与H2O2反应生成羟基自由基(·OH).·OH进攻对苯二甲酸产生唯一的强荧光羟基化产物2 羟基对苯二甲酸(HOTP).·OH清除剂加入体系后,与对苯二甲酸竞争结合·OH,导致对苯二甲酸的羟基化产物HOTP的生成量减少,从而导致体系荧光强度明显降低.我们首次成功地将以上原理运用于中药对·OH清除作用的研究,并于实验中首次发现中药白头翁和半支莲可以清除·OH,两种中药对·OH的清除具有负协同效应,同时测定了它们对·OH的清除率分别为白头翁IC50=1.80×10-2mg/mL;半支莲IC50=1.76×10-2mg/mL.

Evaluation of the Scavenging Effect of Baitouweng, Banzhilian to Hydroxyl Radical by Fluorescence Spectrophotometry

The hydroxyl radical was generated via the reaction of dissolved oxygen with Fe~(2 )-EDTA to produce superoxide radical, which in turn dismutated to H_2O_2, and then Fe~(2 )-EDTA reacted with H_2O_2 to produce hydroxyl radical. When hydroxyl radical-scavenger was introduced to the reaction system, it would compete with terephthalate for hydroxyl radical, and hence decrease the amount of 2-hydroxyterephthalate generated, which in turn decrease the intensity of fluorescence signal. Using this method, the hydroxyl radical-scavenging ability of Chinese traditional medicines was evaluated. The results demonstrated that both traditional medicine Baitouweng and Banzhilian has proved to be effective in scavenging hydroxyl radical, but a negative synergetic effect was observed when Baitouweng and Banzhilian were used together. Scavenging ratio of Baitouweng and Banzhilian for hydroxyl radical were determined.