黄芪异黄酮类化合物抗氧化活性的密度泛函理论研究  

Density functional theory calculations on antioxidation activity of the isoflavone compounds from astragalus

作　　者：张鑫[1] 杨英杰[1] 吕庆章[1] 

机构地区：[1]河南师范大学化学与环境科学学院,河南新乡453007

出　　处：《化学研究与应用》2012年第11期1662-1669,共8页Chemical Research and Application

基　　金：国家自然科学基金资助项目(20972042);河南省杰出青年科学基金资助项目(0612002600)

摘　　要：本文采用密度泛函理论中的B3LYP方法在6-311G(d,p)水平上对黄芪中的四种异黄酮类化合物毛蕊异黄酮、毛蕊异黄酮苷、芒柄花素、芒柄花苷进行了优化计算,从四个分子的几何结构、酚羟基氢原子上的NBO电荷、酚羟基解离能、HOMO和LUMO能级以及其能级差△E(LUMO-HOMO)等方面分析了四种黄芪异黄酮类化合物清除自由基的活性。C3’位的酚羟基为毛蕊异黄酮苷元及其苷分子的最大可能活性位点,C7位酚羟基也具有一定的活性,可以增加分子本身的抗氧化活性,C7位酚羟基为芒柄花素分子的活性位点。C3’位或C7位上酚羟基氢原子带正电荷越大、酚羟基的解离能越小、△E(LUMO-HOMO)越小、HOMO能级相对越高分子的抗氧化活性越高。糖苷取代C7位酚羟基上的H原子,可以提高HOMO、LUMO的轨道能级,但是分子失去了7位酚羟基,从而降低了毛蕊异黄酮苷分子的抗氧化活性。结果表明,四种黄芪异黄酮类化合物的抗氧化能力大小为:毛蕊异黄酮>毛蕊异黄酮苷>芒柄花素>>芒柄花苷。对芒柄花素和羟基自由基反应的过渡态进行了计算研究。The molecular structures of calycosin, calycosin-O-β-D-glucopyranoside, formononetin and ononin are calculated by using the Density Functional Theory B3LYP method with 6-311 G（d,p） basis set. The four compounds having good antioxidant activity to scavenge harmful free radicals for health are isoflavones from astragalus. It is found that the more positive charge on H atom of C3, - OH or C7-OH, the lower bond dissociation energy of the hydroxyl, the higher energy level of the HOMO and the smaller △E（LUMO-HOMO are of benefit to the antioxidant activity of isoflavone compounds. The C3. -OH is the highest active site of calycosin and calycosin-O-β-D-glucopyranoside,while the C7-OH is also an active site but possessing lower activity relatively. The substitution of the H atom of C7-OH by glucoside decreases the antioxidant activity for losing the phenolic hydroxyl in calycosin-O-β-D-glu- copyranoside and ononin. The antioxidant activity of the four compounds goes along with the series Galycosin〉Calycosin-O-β-D-glu- copyranoside〉Formononetin〉〉Ononin. The transition state of the reaction of formononetin scavenging hydroxyl radical is calculated.

关 键 词：黄芪异黄酮 自由基 密度泛函 抗氧化活性 过渡态 

分 类 号：O641.12[理学—物理化学]