用量子化学计算中药大黄提取物大黄素的光敏性  

Quantum chemistry calculation research on photosensitivity of emodin from rheum

作　　者：赵雪[1] 冯帅[1] 陈德展[2] 

机构地区：[1]泰山学院化学与环境科学系,山东泰安271021 [2]山东师范大学化学化工与材料科学学院,山东济南250014

出　　处：《计算机与应用化学》2010年第3期382-386,共5页Computers and Applied Chemistry

基　　金：国家自然科学基金资助项目(20573070)

摘　　要：大黄素作为天然蒽醌类染料,因其在可见光照射之下的良好光致生物活性而越来越受关注。考虑到含时密度泛函理论(TD-DFT)在研究光敏剂光物理化学过程中应用成功,本文用其研究大黄素激发态的各种性质,并用连续介质模型(PCM)讨论溶剂效应对激发态行为的影响。发现:(1)在无氧条件下,溶剂中大黄素可损伤DNA,原因是碱基对与大黄素阳离子之间的电子转移所致,并非由其三重激发态与碱基对直接作用而引起。而阳离子的产生是依赖容剂中2个邻近的三重态大黄素分子间的自离子化反应;(2)在有氧的环境中,大黄素的去激发能可以提供足够的能量与氧气之间发生能量转移而产生单重态氧;溶剂效应降低大黄素的电离势及电子亲和势,使其在水中更容易放出电子。当大黄素被还原后,在气相中氧的氧化能力不足以夺取大黄素负离子的电子而产生超氧阴离子,而在溶剂中这一反应却可能发生。As a naturally occurring anthraquinone pigments, emodin has attracted considerable attention in recent years owing to its efficient photosensitivity under solar spectrum. Considering the successful use of time-dependent density functional theory （TD-DFT） in investigating the photo-physicoehemical behaviors of dyes and pigments, we perform the study by means of TD-DFT calculations, which provide us various excited state properties of emodin, including absorption spectrum, lowest triplet excited-state energy, vertical electron affinity and vertical ionization potential. On the basis of the calculated results, the photosensitive mechanisms of emodin were discussed and some deeper insights were gained. First, we indicated that the experimentally observed chrysophanol＇s photo-damage to DNA in oxygen-free media is more likely arises from EMO ＋ rather than from T1 state chrysophanol. Second, we revealed that it is the EMO - that is responsible for the O2- generation in solvents. Based on the photosensitive activities, emodin may be potentially used as the photodynamic medicine for clinical therapy of the diseases occurring on the shallow surface and vascular capillare diseases,

关 键 词：含时密度泛函 大黄素 激发态 垂直电子亲和势 垂直电离势 

分 类 号：TQ015.9[化学工程] O6-39[理学—化学]