4种甘草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 four flavones from radix glycyrrhizae

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：《计算机与应用化学》2012年第6期656-660,共5页Computers and Applied Chemistry

基　　金：国家自然科学基金资助项目(20673034);河南省杰出青年科学基金资助项目(0612002600)

摘　　要：甘草中的4种黄酮类化合物甘草素、异甘草素、甘草苷、异甘草苷具有抗氧化、抗肿瘤、抗HIV等生物活性,具有潜在的药用价值。本文采用密度泛函理论(DFT)中的B3LYP方法在6-311G(d,p)基组水平上对甘草中的4种黄酮类化合物甘草素、异甘草素、甘草苷、异甘草苷进行了优化计算,从4个分子的几何结构、氢原子的NBO电荷、羟基解离能、HOMO、LUMO、ΔE_(LUMO-HOMO)等方面分析了4种甘草黄酮类化合物清除自由基的机理。结果表明,4种甘草黄酮类化合物的抗氧化能力大小为异甘草素≧异甘草苷>>甘草素≧甘草苷。C_7位的酚羟基为最大可能活性位点,容易发生抽氢反应,C_(4’)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。C_7位上酚羟基的解离能越小、羟基氢原子带正电荷越大、HOMO能级相对越高、ΔE_(LUMO-HOMO)越小分子的抗氧化活性越高。2、3位C=C双键可以增大分子的共轭体系,从而增大分子的抗氧化活性;糖苷的取代,增加了HOMO、LUMO轨道能级,但是分子失去了4’位酚羟基,所以从整体上降低了分子的抗氧化活性。The geometrical structures of the four main compounds of glycyrrhiza flavonoids, liquiritigenin, liquiritin, isoliquiritigenin and isoliquiritoside, which have potential medicinal value of antioxidant activity, remarkable anti-tumor and anti-HIV effects, have been calculated by using the Density Functional Theory （DFT） B3LYP method with 6-311G （d,p） basis set. The properties of the glycyrrhiza flavonoids have been discussed in detail based on their molecular structures, NBO charges on hydrogen atoms, the dissociation energy of O-H bonds, the energies of the highest occupied molecular orbital（HOMO） and the lowest unoccupied molecular orbital（LUMO）, the energy gap between HOMO and LUMO, and etc. The results showed that CT-OH is likely the most active site to eliminate free radicals in human body by dehydrogenation, while the 4＇-OH also is probably an active site to enhance the antioxidant activity of the molecules. Smaller 7-OH bond dissociation energy of hydroxyl, bigger positive charge value on hydrogen atom, relatively higher the HOMO energy, and smaller △E（LUMO-HOMO） and LUMO, but, at the same time, the losing 4＇-OH decreases the total molecular antioxidant activity since lost one active site. As a result, it was revealed that the antioxidant activity of the compounds goes along with the series Isoliquiritigenin =〉 Isoliquiritoside 〉〉 Liquiritigenin ≥ liquiritin.

关 键 词：甘草黄酮 自由基 密度泛函 抗氧化活性 

分 类 号：O641.12[理学—物理化学]