【作者】 彭国文；

【导师】 聂长明；

【作者基本信息】 南华大学 ， 市政工程， 2007， 硕士

【摘要】 定量结构-活(毒)性(Quantitative Structure–activity Relationship,QSAR)方法是目前国际上一个最为活跃研究领域,QSAR的研究对象包括化合物的生物活性、毒性、药物的各种代谢的动力学参数和生物的利用度以及分子各种物理化学特性和环境化学行为等,研究的领域涉及生物、化学以及环境科学等诸多学科。QSAR研究的方法是从化合物的分子结构和活(毒)性的实验结果出发,依据不同需要和研究深度,可建立二维、三维或多维模型,来估测未知化合的生物活(毒)性或其他生态学效应。本论文从分子结构的定量描述和结构性质定量关系的建立,研究了QSAR在部分复杂有机污染物在环境中的生物活(毒)型的应用。化合物的结构决定其性质,并且每种性质都与其结构密切相关,因此通过分析和考察分子结构特征与物理化学性质或生物活性之间的变化规律,建立物质结构与性质的定量关系,并从理论上对物质的性质和功能进行解释和预测具有十分重要的意义,其关键是找到能够反映物质本身而又简单的分子描述符。(1)作者根据20个取代氯苯酚化合物分子结构特征,分别构建出一种既能表征取代基差异,又能反映出取代位置的分子结构描述符,利用多元线性回归技术建立分子结构参数与取代氯苯酚化合物对microtox(发光细菌)、guppy(花鳞鱼)、bluegill(翻车鱼)、trout(鲑鱼)4种水生物急性毒性的相关模型,结果表明所建模型均有较好的稳定性和较强的外部预测能力。(2)作者应用支持向量回归算法和采用多环芳烃分子的几何参数,包括分子的环数N、宽度B、长度L、分子体积V、顶连接指数XV和边连接指数XE等作为特征量进行回归计算得到了多环芳烃在空气-正辛醇分配比、多环芳烃在土壤中吸附参数、多环芳烃的生物浓度因子与分子几何参数关系的数学模型,使用留一法证明发现数学模型的预报可靠性较PLS算法建立的数学模型略优。(3)作者根据含杂原子化合物分子中成键原子i的结构特征和所处的化学环境,在分子图的邻接矩阵和距离矩阵基础上,用分子中原子的平衡电负性对分子图的顶点着色,构建一组能表征杂原子、多重键的分子结构特征的拓扑指数,并定义基团定位基参数β。然后利用它们对单硫醚及脂肪醇、烷氧氯硅烷的理化性质进行相关性研究,结果表明化合物的性质P可用P=a0E+b1E+cβ+d定量描述。这组指数不仅能有效区分化合物中同种原子在不同化学环境中的差别,而且指数具有高的结构选择性,并对分子结构实现了唯一表征。更多还原

【Abstract】 Quantitative structure–activity relationship(QSAR) methods, are the most promising and successful tools to provide rapid and useful meanings for predicting the biological activity or toxicities of organic compounds by use of different statistical methods and various kinds of molecular descriptors. The goals of QSAR is to develop models on a training set of compounds, these models will then allow for the prediction of the biological activity or toxicities of related chemicals. This kind of study can not only develop a method for the prediction of the property of compounds that have been synthesized but also can identify and describe important structural features of moleculars that are relevant to variations in molecular propertise, thus gain some insight into instrutural factors affecting molecular propertise. Now, QSAR method has been introduced to biology, chemistry and environment science. In the dissertation, we mainly discuced the application of QSAR in the study on the biological activity or toxicities of some complex organic pullutants in the environment, according to molecular descriptors of struture and establish the relationships between structure and activity(toxicity).Compound structures determine their nature and each character is closely related to their structures. Therefore, it is great significant that analysis and study their change rules between molecular structure characterizations and physico-chemical properties or biological activities. Building quantitative relationships between molecular structures and properties, and explaining and predicting the properties and functions of the material from theory are very important to quantitative structure activity/property relationships (QSAR/QSPR). The key is to find the simple molecular structural descriptors which can efficiently reflect the molecular itself.(1) We built series simple descriptors according to molecular structural characterization of 20 substituted phenols. The molecular descriptors can not only represent substituents′differences, but also reflect the positions of substituents. The equations were established between molecular structure parameters and phenols acute toxicity for microtox, guppy, bluegill, trout, by using multivariate linear regression method. The results indicate that the models built by our methods show both better stability and stronger external predictive capability.(2) In this dissertation, support vector regression had been used for correlating and modeling the relationships between the geometrical parameters and environmental behaviors of polycyclic aromatic hydrocarbons. The prediction ability of the mathematical models obtained was somewhat better than that obtained by PLS regression.(3) We introduced an equilibrium electronegativity topology index mE(m=0,1) based on the structural characteristic bonding atom i and its mirror chemical surrounding of heteroatomic compounds, according to the adjacency matrix by defining equilibrium electronegativity of atoms and coloring atoms in molecular graph with equilibrium electronegativity,which was done through improvingδvi of atoms in the valence connection index,and defined a locating group parameterβ.And we also put the correlativity research on physicochemical properties of sulfides and aliphatic alcohols、alkoxy silicon chlorides.The results appeared that the physicochemical properties P of heteroatomic compounds can be described as follows:P=a0E+b1E+cβ+d.With this new method,calculation was convenient,and the results were accurate and had clear physical meanings.In addition,the novel topology index mE had unique to the molecular structures and excellent structural selectivity.The calculated results by the formula indicated that the average relative deviations between calculated values and experimental data were among the experimental deviations.更多还原