CAJ | 학술논문

利用密度泛函理论的B3LYP交换相关泛甬对从细梗胡枝子中提取的一种新型黄酮类化合物的分子结构和抗氧化活性进行了研究,获得了该化合物的中性分子、阴离子、自由基和自由基阳离子的稳定几何构型和能量.通过分析前线分子轨道特征,确定了与实验结果一致的现象:A环是参加化学反应的活性部位,并发现A'环也是重要的抗氧化活性部位.为判断其抗氧化活性,预测其水溶液中,中性和阴离子的电离势分别为509.0和432.2 kJ·mol~(-1),均裂O-H键解离能为347.3 kJ·mol~(-1),羟基自由基电子亲和势和氢原子亲和势分别为-620.6和-487.5 kJ·mol~(-5).通过理论分析比较,该黄酮类化合物清除羟基自由基的三种机理即H原子转移、电子转移-质子转移和质子丢失-电子转移在热力学上并存,其中质子丢失-电子转移是热力学最有利的机理.本文为设计新型高效黄酮类抗氧化剂,研究黄酮类化合物的构效关系和抗氧化机理提供了理论依据.
이용밀도범함이론적B3LYP교환상관범용대종세경호지자중제취적일충신형황동류화합물적분자결구화항양화활성진행료연구,획득료해화합물적중성분자、음리자、자유기화자유기양리자적은정궤하구형화능량.통과분석전선분자궤도특정,학정료여실험결과일치적현상:A배시삼가화학반응적활성부위,병발현A'배야시중요적항양화활성부위.위판단기항양화활성,예측기수용액중,중성화음리자적전리세분별위509.0화432.2 kJ·mol~(-1),균렬O-H건해리능위347.3 kJ·mol~(-1),간기자유기전자친화세화경원자친화세분별위-620.6화-487.5 kJ·mol~(-5).통과이론분석비교,해황동류화합물청제간기자유기적삼충궤리즉H원자전이、전자전이-질자전이화질자주실-전자전이재열역학상병존,기중질자주실-전자전이시열역학최유리적궤리.본문위설계신형고효황동류항양화제,연구황동류화합물적구효관계화항양화궤리제공료이론의거.
The molecular structures and antioxidant activities of a novel flavonoid-type compound (lespedezaflavonone)from Lespedeza virgata were studied using density functional theory (DFT) with the B3LYP exchange correlation functional. The optimized geometries of neutral, radical cation, radical, and anion forms of lespedezaflavonone were obtained. Ring A was found to be responsible for the high activity of the flavonoids by an analysis of the character of the frontier molecular orbital, which was consistent with what was observed experimentally. Furthermore, it was noteworthy that ring A' was firstly found to be the important part for the potent antioxidant activity of lespedezaflavonone. To quantify the antioxidant activities, we determined the adiabatic ionization potential (IP, 509.0, 432.2 kJ·mol~(-1) for the neutral and anion forms, respectively), the homolytic O-H bond dissociation enthalpy (BDE, 347.3 kJ·mol~(-1)) for lespedezaflavonone, the adiabatic electron affinity (EA, -620.6 kJ·mol~(-1)) and the H-atom affinity (HA, -487.5 kJ·mol~(-1)) for hydroxyl radical in aqueous solution. Our theoretical analysis shows that H-atom transfer, stepwise electron-transfer-proton-transfer, and sequential proton-loss-electron-transfer mechanisms for lespedezaflavonone to scavenge hydroxyl radical may occur thermodynamically in parallel while the last process is the most favorable. These findings are helpful for further study on the design of novel efficient flavonoid-type antioxidants, the structure-activity relationship and the antioxidant mechanism of flavonoid-type compounds.