昆仑雪菊中5个黄酮类化合物抗氧化活性的DFT研究

Study on Antioxidant of Five Flavonodis in Coreopsis tinctoria Nutt. by DFT

采用量子化学密度泛函理论(DFT)的B3LYP/6-311G++(2d,2p)//B3LYP/6-31G方法,对昆仑雪菊中已分离得到的5个黄酮类化合物(马里苷、金鸡菊噢、黄杉素、紫铆因和奥卡宁)进行了优化及单点能计算。从黄酮分子的几何构型、氢键数目、不同位置酚羟基的解离焓(BDE)、HOMO和LUMO前线分子轨道图及其能级差分析所得,昆仑雪菊黄酮类化合物的羟基数目和形成的分子内氢键数目越多,抗氧化活性越强;羟基的活性因其位置不同而有所差异,且5个化合物B环4'位羟基的解离焓都最小,是抗氧化作用的主要活性位点;C环3位羟基的存在并没有提高黄杉素的抗氧化活性。

Using B3LYP/6-311G＋＋（2d,2p）//B3LYP/6-31G method of density functional theory calculated and optimized energy of five flavonoids of Coreopsis tinctoria Nutt.,including marein,maritimetin,taxifolin,butein and okanin. By the analysis of the molecular geometry,BDE of different position of the phenolic hydroxyl group, HOMO and LUMO frontier molecular orbital diagram and its energy gap,theoretical antioxidant activity of flavonoids are elucidated. And the results show that：antioxidant activity of flavonoids of Coreopsis tinctoria Nutt. related to the number of hydroxy group and the number of the hydrogen bonds;the activity of hydroxyl groups in different positions are different,and the BDE of 4＇-hydroxyl in ring B of all five flavonoids are minimal,so 4＇-hydroxyl is their main antioxidation active site;and 3-hydroxyl group in ring C did not increase the antioxidant activity of taxifolin.