蒲公英黄酮抗氧化活性的构效关系分析

Structure and Antioxidant Activities Relationship of Dandelion Flavonoids

为从分子水平研究蒲公英黄酮结构与抗氧化活性之间的内在关系,本文借助于密度泛函理论,通过优化结构参数、捕获自由基的热力学能量分析、NBO电荷分布、半醌自由基的自旋密度分析等深入探讨了蒲公英黄酮化合物(槲皮素、芦丁、木犀草素、芹菜素、香叶木素等)抗氧化活性的构效关系及内在规律。结果表明,5种蒲公英黄酮化合物抗氧化活性顺序为:芦丁>槲皮素>木犀草素>>香叶木素>芹菜素,酚羟基的位置是影响蒲公英黄酮抗氧化活性差异的主要因素。蒲公英黄酮不同位点抗氧化活性的高低与其酚羟基上H原子的电荷分布、黄酮自由基的稳定性成正比关系,自由基单电子的离域程度和分子内氢键的稳定化作用共同决定了B环4′-OH是蒲公英黄酮的关键活性位点。

To study the intrinsic relationship between the structure and its antioxidant activity of dandelion flavonoids from the molecular level,five important flavonoids in dandelion(quercetin,rutin,luteolin,apigenin,diosmetin)were systematically analyzed by density functional theory(DFT)calculations.The optimized geometric configuration,the relative change in energy(ΔH)associated with the formation of various flavonoid radicals,the NBO charges and spin densities analysis of the five aforementioned flavonoids were compared.The results indicated that the order of antioxidant properties is rutin>quercetin>luteolin>>diosmetin>apigenin,the location of phenol hydroxyl group significantly affects the antioxidant properties of dandelion flavonoids.The radical scavenging activity of different reactive site(-OH group)is related to the charges on H atom and the stability of flavonoid radicals,the electron delocalization and intramolecular hydrogen bond finally lead to the high activity of 4′-OH in ring B of dandelion flavonoids.