利用密度泛函理论分析蓝莓花色苷抗氧化活性

Analysis of Antioxidant Activity of Blueberry Anthocyanins Using Density Functional Theory

运用高效液相色谱法(high performance liquid chromatography,HPLC)和HPLC-电喷雾质谱联用技术对4个不同品种蓝莓中花色苷进行组分鉴定及含量分析,采用氧自由基吸收能力体外抗氧化实验分析13种花色苷单体的抗氧化能力,在此基础上利用密度泛函理论在M062-x/6-311++G**水平上对13种花色苷分子结构参数、活性羟基的解离能(bond dissociation energy,BDE)、电离势(ionization potential,IP)及半醌式自由基自旋密度分布进行计算,对不同品种蓝莓花色苷抗氧化活性的差异进行分析。结果表明,花青素半乳糖苷的抗氧化能力高于同类花青素阿拉伯糖苷和葡萄糖苷,矮牵牛素-3-O-半乳糖苷的抗氧化能力最强,其酚羟基BDE仅为251.21 kJ/mol,IP仅为484.51 kJ/mol,半醌式自由基的自旋密度分布仅为0.03278。本实验分析了蓝莓果中花色苷含量及其与抗氧化能力间的关系,抗氧化密度泛函理论计算结果与体外抗氧化实验结果一致,可见DFT计算方法为蓝莓花色苷抗氧化活性研究提供了理论依据。

High performance liquid chromatography(HPLC)and high performance liquid chromatography-electrospray ionization-mass spectrometry(HPLC-ESI-MS)were used to analyze the anthocyanins in four different blueberry varieties.The antioxidant capacity of 13 anthocyanins was determined in vitro using the oxygen radical absorbance capacity(ORAC)assay,and the molecular structure parameters,active hydroxyl bond dissociation energy(BDE),ionization potential(IP)and semi-quinone free radical spin density distribution were calculated by using density functional theory(DFT)at the M062-x/6-311++G**level.Furthermore,the difference in the antioxidant activity of anthocyanins was evaluated among blueberry varieties.The results showed that the antioxidant capacity of anthocyanidin galactosides was higher than that of arabinoglycosides and glucosides originating from the same anthocyanindins.The antioxidant capacity of petunia-3-O-galactoside was found to be the strongest among the 13 anthocyanins,with BDE,IP and spin density of semi-quinone radical of only 251.21 kJ/mol,484.51 kJ/mol,and 0.03278,respectively.The theoretical calculation of antioxidant capacity was consistent with the results of antioxidant assay in vitro.In addition,the relationship between anthocyanin content in blueberry fruit and antioxidant capacity was analyzed.This study indicated that the DFT method provides a theoretical basis for studies on the antioxidant activity of blueberry anthocyanins.