Study on the Mechanism of Antioxidant Response of Pterostilbene Based on DFT

本文通过密度泛函理论(DFT)方法，研究了紫檀芪与·OH和·OOH自由基在不同溶剂中抗氧化活性的大小。从前线分子轨道结合福井函数与双描述符对紫檀芪活性位点进行预测，通过酚羟基键解离焓(BDE)、电离电位和质子解离焓(IP和PDE)、以及质子亲和力与电子转移焓(PA和ETE)进行分析，在H原子抽取机制中H原子直接转移(HAT)机制、逐步电子转移–质子转移(SET-PT)机制、质子优先损失电子转移(SPLET)机制中分析主导机制。讨论了紫檀芪在H原子抽取与自由基加成(RAF)机制中反应活性位点与·OH和·OOH自由基的反应能量。结果表明在气相中紫檀芪与·OH反应通过在中心不饱和碳自由基加成机制；与·OOH反应通过在酚羟基上H原子抽取机制。In this paper, the magnitude of antioxidant activity of Astragalus purpurascens with ·OH and ·OOH radicals in different solvents was investigated by density flooding theory (DFT) method. The prediction of the active site of Zygostatin from the frontline molecular orbitals combined with Fukui functions and dual descriptors was analyzed by the phenolic hydroxyl bond dissociation enthalpy (BDE), ionization potential and proton dissociation enthalpy (IP and PDE), as well as the proton affinity and electron transfer enthalpy (PA and ETE), and the dominant mechanism was analyzed in the H-atom abstraction mechanism, the H-atom direct transfer (HAT) mechanism, the stepwise electron transfer-proton transfer (SET-PT) mechanism, and proton preferential loss electron transfer (SPLET) mechanism. The reaction energies of the reactive sites of Pterostilbene in the H-atom extraction and radical addition (RAF) mechanism with ·OH and ·OOH radicals were discussed. The results indicate that in the gas phase Astragalus purpurascens reacts with ·OH via an unsaturated carbon radical addition mechanism at the center; and with ·OOH via an H atom extraction mechanism at the phenolic hydroxyl group.