分子拓扑学参数及其在定量结构——活性相关(QSAR)研究中的应用

本文阐述了定量结构—活性相关研究中常用的几个拓扑学参数的定义及其计算方法,对相关数据进行了归纳整理,并通过实例阐述了拓扑学参数在ＱＳＡＲ研究中的重要作用。     

酚类化合物对硝化颗粒污泥活性抑制的定量结构 活性相关研究

测定了酚类化合物对硝化颗粒污泥活性抑制的logIC₅₀值,以量子化学参数为自变量,应用偏最小二乘法（PLS）,建立了酚类化合物对硝化颗粒污泥活性抑制的定量结构活性相关（QSAR）模型。模型所提取的PLS主成分所能解释的因变量总方差的比例Q²_cum为0.820,表明模型具有较好的稳定性和预测能力。模型的结果表明,影响酚类化合物对硝化颗粒污泥活性抑制的主要因素是logkow、CCR和E_homo,酚类化合物对硝化颗粒污泥活性抑制的logIC₅₀随着分子logkow的增大而减小,随着E_homo和CCR的增大而增大。     

酚类化合物对硝化颗粒污泥活性抑制的定量结构-活性相关研究

测定了酚类化合物对硝化颗粒污泥活性抑制的logIC50值,以量子化学参数为自变量,应用偏最小二乘法（PLS）,建立了酚类化合物对硝化颗粒污泥活性抑制的定量结构-活性相关（QSAR）模型。模型所提取的PLS主成分所能解释的因变量总方差的比例Qc2um为0.820,表明模型具有较好的稳定性和预测能力。模型的结果表明,影响酚类化合物对硝化颗粒污泥活性抑制的主要因素是logkow、CCR和Ehomo,酚类化合物对硝化颗粒污泥活性抑制的logIC50随着分子logkow的增大而减小,随着Ehomo和CCR的增大而增大。     

染料结构-光催化降解活性关系初步研究

以近20种水溶性染料为研究对象,选择正辛醇-水分配系数(Kow)、分子最高占据轨道能(EHOMO)及分子最低空轨道能(ELUMO)等理化参数,建立了染料的定量结构-光催化降解反应活性关系模型,得到定量关系式为:lgk＝0.016 28×lgKow 0.132 46×(ELUMO-EHOMO)-2.148 56,很好地表示反应活性与结构之间的定量关系,为水溶性染料的光催化降解活性预测提供了有效的工具.     

几种农药对发光菌毒性的测定和构效关系研究

测定了10种农药对发光菌的毒性数据(-lgEC50);采用密度泛涵理论(DFT)中的B3LYP方法,在B3LYP/6-31G*水平上全优化计算了17种农药的结构参数和热力学参数,将这些参数作为理论描述符,依据修正的线性溶解能理论,利用半致死浓度(EC50)实验数据,建立了用于预测农药毒性的模型,其相关方程(相关系数r=0.945 5)包含2个变量,即分子的最正氢原子电荷(qH )和熵(Sθ),并用留一交叉验证法对模型的稳定性进行了验证.此外,还利用该模型预测了17种农药对发光菌的一IgEC50.     

卤代芳烃对水生生物急性毒性的定量构效关系研究

提出表征成键原子生物活性的点价 βi,由 βi 建构新的价连接性指数nH ,并用 0阶指数0 H ,1价指数1H研究了卤代芳烃 (含F、Cl、Br、OH、NH2 、NO2 和烷基等 )对发光菌、呆鲦鱼、斜生栅列藻的急性毒性 ,给出了相关方程。结果表明 ,新方法计算简单 ,应用方便 ,估算结果均优于相应的文献方法     

磺酰脲类除草剂研究进展

本文较全面地概述了近几年国内外有关磺酰脲类除草剂的分析测试和降解方式等方面的研究现状,着重讨论了磺酰脲类化合物的结构活性相关和风险评价等方面的研究进展     

定量构效关系模型分析氯代烯烃中氯原子对其分子描述符的影响

定量构效关系(QSAR)模型在研究饮用水消毒副产物(DBPs)中氯原子数量与毒性的关系方面有一定进展,然而,能够反映DBPs毒理性的分子描述符和氯原子数量之间的相关性却从未被系统地和定量的研究.分子描述符的计算是QSAR研究的基础,其中分子轨道能,如最低空轨道能量(ELUMO)是应用最广的量化参数之一.基于QSAR方法建模筛选氯代烯烃同系物的相关量子化学参数,检验最高占据轨道能级(EHOMO)、碳原子数(NC)、氯原子数(NCl)对ELUMO的贡献作用.并通过统计学方法进行模型开发和内外交叉法验证发现,NCl和NC是预测氯代烯烃分子特性较重要的两个化学参数,即较稳健的模型为ELUMO=-0.0205NCl+0.0059NC+0.1641(n=11, R2=0.9956, F=102.8569, RMSE=0.0019).此外,为了提高模型的准确性,使用蒙特卡罗法对模型进行不确定性分析,来进一步评估这些参数的误差源传输到ELUMO计算时,对ELUMO的影响.     

Insights into the structure of urea-like compounds as inhibitors of the juvenile hormone epoxide hydrolase (JHEH) of the tobacco hornworm Manduca sexta: analysis of the binding modes and structure-activity relationships of the inhibitors by docking and CoMFA calculations

Substituted urea compounds are well-known as potent inhibitors of juvenile hormone epoxide hydrolase (JHEH) of the tobacco hornworm Manduca sexta. Docking simulations of 47 derivatives inside JHEH were performed to gain insight into the structural characteristics of these complexes. The obtained orientations show a strong similitude with the observed in the known X-ray crystal structures of human soluble epoxide hydrolase (sEH) complexed with dialkylurea inhibitors. In addition, the predicted inhibitor concentration (IC₅₀) of the above-mentioned compounds as JHEH inhibitors were obtained by a quantitative structure-activity relationship (QSAR) method by using comparative molecular field analysis (CoMFA) applied to aligned dataset. The best models included steric and electrostatic fields and had adequate predictive abilities. In addition, these models were used to predict the activity of an external test set of compounds that was not used for building the model. Furthermore, plots of the CoMFA fields allowed conclusions to be drawn for the choice of suitable inhibitors.     

有机化合物动态定量结构——生物降解关系(QSBR)模型研究

本文通过分析一般ＱＳＢＲ模型应用的特点、不足和影响有机物生物降解的基本因素,指出ＱＳＢＲ模型应综合反映影响有机物生物降解的四个方面（以氯代芳香化合物为例）：氯代苯系物的摄入、氯代苯系物的诱导作用、毒性物质的形成和基础酶的缺乏。在此基础之上给出了动态ＱＳＢＲ的概念模式及方法学基础。     

聚硅硫酸钛（PTSiS）的合成及形貌分析

以硅酸钠和硫酸钛为原料,用共聚法制备了不同硅钛比(硅钛摩尔比分别为3∶1、1∶1和1∶3)的新型绿色无机高分子絮凝剂——聚硅硫酸钛(PTSiS)。用紫外连续扫描光谱仪(UV/Vis)、红外光谱仪(IR)、X-射线衍射(XRD)、扫描电镜(SEM)和倒置生物显微镜对样品中钛硅的微观品貌进行了多方面物性分析。结果表明:当硅钛比为3∶1时,硅酸钠和硫酸钛反应完全。此时,聚硅酸的骨架硅(Si—O—Si)与钛元素发生同晶取代或与钛离子水解形成的表面羟基发生络合,形成的聚硅硫酸钛(PTSiS)是一种高分子的硅钛聚合物,而不是单纯的原料混配。另外,聚硅硫酸钛(PTSiS)具有枝杈长链的网络结构,其骨架主要由框架钛结构(Ti—O—Si)组成。     

Influence of several fungicides on the antioxidant activity of red wines (var. Monastrell)

The antioxidant activity of wines obtained from grapes treated with six fungicides (famoxadone, fenhexamid, fluquinconazole, kresoxim-methyl, quinoxyfen and trifloxystrobin) was investigated. Two field trials in triplicate were carried out for each formulation of the fungicide at the recommended dose of the manufacturer. The first trial was carried out under good agricultural practices (GAP), following the recommended pre-harvest interval, and the second one under critical agricultural practices (CAP) that involves treating the same field just before the harvest. The residue levels were determined by gas and liquid chromatography coupled to mass detectors (GC-MS and LC-MS). The antioxidant activity was determined in the wines obtained from the thirteen trials including one control, six from treated grapes obeying the pre-harvest interval, and six from grapes treated at the day of harvest or at most unfavorable conditions. Elimination of 40–100% of the initial fungicide residues present in grapes was observed during the wine-making process. It can be inferred from the results that the use of these fungicides did not produce any decrease of the antioxidant activity in the wines (7.19 ± 0.22 mmol Trolox/L for the blank wine versus a range of 6.45 ± 0.82 mmol Trolox/L to 10.06 ± 0.59 mmol Trolox/L for the treated wines) at the pre-harvest interval and most unfavorable conditions. Nevertheless, the presence of famoxadone, kresoxim-methyl and quinoxyfen increased the antioxidant activity and this was directly related to their residue levels in the grapes. Also, the wine phenolic composition was altered in variable intensity by the presence of the fungicide residues.     

降解聚丁二酸丁二醇酯菌株的诱变选育及降解性能

诱变选育是基因资源开发的重要手段之一,为了对降解聚丁二酸丁二醇酯(PBS)菌株的降解性能进行改良,选择具有一定降解PBS能力的尖孢镰刀菌(Fusarium oxysporum)DSCF-8为出发菌株,分别研究了其在5种诱变途径下的突变效应及最佳诱变条件,测定了突变菌株D8B14在不同条件下的降解性能。结果表明,复合诱变途径的高效降解菌株获得率大于单因子诱变途径,分别达到了4.55%和1.30%,但突变株的降解特性遗传不稳定;硫酸二乙酯单因子诱变效应大于紫外线诱变和微波诱变,且得到的突变株较复合诱变得到的菌株具有更强的遗传稳定性,最佳诱变条件为5%的浓度处理40 min。硫酸二乙酯诱变得到的突变株D8B14传代稳定且降解性能优异,其对PBS薄膜的降解率较出发菌株提高了34.49%,粗酶液酶活性提高率为23.86%。该突变株在35℃条件下仍表现出较高的降解能力,对不同的初始pH条件亦具有更强的耐受能力,尤其在pH 4.0或pH 9.0的酸性和碱性条件下,降解率分别提高了13.26%和27.04%。