天然黄酮类化合物清除DPPH^＊的构效关系

Structure-activity Relationship of the Natural Flavonoids in Scavenging DPPH·

应用DPPH.分光光度测定法研究了11种高纯度的天然黄酮类化合物清除二苯代苦味肼基自由基(DPPH.)的构效关系。结果表明,这11种天然黄酮类化合物都能有效地清除DPPH.,其清除DPPH.作用大小顺序依次为:槲皮素>泽漆新苷>儿茶素>金丝桃苷>芸香苷>山奈素>桑色素>异槲皮苷>黄芩苷>石吊兰素>金雀异黄素。发现这11种天然黄酮类化合物有如下构效关系:1.B环上和/或A环上具有邻位羟基可大大增强清除DPPH.作用;2.B环上4′位羟基和A环上6位羟基清除DPPH.的活性都很强;3.异黄酮清除DPPH.的活性弱于相应的黄酮;4.黄酮醇清除DPPH.的活性强于相应的双氢黄酮醇,提示C环具有C2-C3双键结构可增强清除DPPH.作用;5.黄酮类化合物对DPPH.的清除能力与其酚羟基位置密切相关;6.C环3位上羟基被糖基化时,其清除DPPH.的作用减弱。所得结果为进一步开发利用黄酮类化合物提供了理论依据。

The production and development of many diseases is closely related to oxidative damages caused by free radicals. So it becomes one of investigating hotspots that safe and effective antioxidants in plants are searched. And the spectrophotometry for detecting 1,1-diphenyl-2-picryl-hyrazyl radical （DPPH＇） is a rapid, simple and sensitive method for screening antioxidants. Therefore, the structure-activity relationship of eleven pure and natural flavonoids scavenging DPPH^＊ were studied by using the spectrophotometry for detecting DP- PH^＊ . The results showed that all of the eleven natural flavonoids can scavenge DPPH^＊ effectively. The DPPH^＊ - scavenging ability in turn was： quercetin 〉 heliosin 〉 catechin 〉 hyperoside 〉 rutin 〉 kaempferol 〉 morin 〉 isoquercitroside 〉 baicalin 〉 nevadensin 〉 genistein. Therefore it was discovered that the structure-activity relationship of the eleven natural flavonoids scavenging DPPH^＊ was as follows ： 1. B ring and/or A ring with adjacent hydroxyl groups could greatly increase their DPPH^＊ -scavenging ability; 2. The hydroxyl groups in 4＇position on the B ring and the hydroxyl group in 6 position on the A ring possessed the high DPPH^＊ -sca-venging activity; 3. The DPPH^＊ -scavenging activities of isoflavonoids were weaker than those of corresponding flavonoids; 4. The DPPH^＊ -scavenging activities of flavonols were stronger than those of corresponding flavanonols. It suggested that C ring with C2-C3 double bond could enhance its DPPH^＊ -scavenging effect; 5. The DPPH^＊ -scavenging ability of flavonoids was closed related to the positions of their hydroxyl groups; 6. When the hydroxyl group at 3 position on the C ring was glycosylated, its DPPH^＊ -scavenging activity was decreased. These results provide a theoretical basis for further exploiting and utilizing flavonoids.