基于支持向量机回归与K-最近邻法的组合预测用于除草剂QSAR建模

为了提高定量构效关系(QSAR)研究的预测精度,发展了一种基于支持向量机回归(SVR)与K-最近邻法(KNN)的组合预测方法:以均方误差(MSE)最小为原则,基于SVR实施核函数寻优;基于MSE最小原则与最优核函数以SVR进行描述符筛选并得到保留描述符;通过"多轮末尾强制淘汰法"揭示各保留描述符对预测精度的影响程度;从保留描述符出发,以不同KNN预测值反映样本集异质性并构建子模型,然后基于SVR以留一法实施组合预测。运用该组合预测方法研究苯乙酰胺类除草剂QSAR建模,结果表明:基于SVR与KNN的组合预测方法在参比模型中预测精度最高,具结构风险最小、非线性、能有效克服过拟合、泛化推广能力优异等优点,在QSAR研究中具有广泛的应用前景。     

新型茉莉酸类植物生长调节剂的QSAR研究

应用 Cerius2 软件中的遗传函数算法(GFA)和分子力场分析方法(MFA)对18个新型茉莉酸类化合物具有的对大麦和番茄的生物活性进行定量构效关系(QSAR)研究,所建模型都通过了显著性检验,交叉验证系数r2CV均大于0.810,表明模型都具有良好的预测可靠性。计算研究表明: 分子的热力学性质 (各种原子类型 AlogP 描述符)、空间结构状态(Jurs-RPSA参数)、 电性描述符(Dipole-mag 和 HOMO)和结构描述符(Hond Acceptor)是影响活性的主要二维因素。用三维QSAR方法研究了茉莉酸类化合物与其受体有效相互作用时所需的理化特征,并进一步验证了二维QSAR模型的可靠性。该研究可为进一步了解茉莉酸类化合物在植物体内的信号传导机制和研制具有生态农药性质的茉莉酸类植物生长调节剂提供理论指导。     

新型含噻唑和三唑环的亚胺类杀菌剂的QSAR研究

应用Cerius2软件中的主成分分析法(PCA)和Var.Jarvis-Patrick聚类方法对新型含噻唑和三唑环的亚胺类杂环化合物进行分类,再用遗传函数算法(GFA)和分子力场分析方法(MFA)分别进行了二维/三维定量构效关系研究(QSAR),所建模型都通过了显著性检验,CV-r2均大于 0.910,表明模型都具有良好的预测可靠性。计算研究表明:分子的热力学性质(各种原子类型AlogP描述符)、空间结构状态(Jurs参数和Shadow参数)和电拓扑状态指数(S_aaCH)是影响活性的主要二维因素。三维研究结果表明,分子的静电作用强弱对活性影响较大。最后根据药物分子设计理论设计了一系列亚胺类化合物,并用所建最优二维/三维QSAR模型进行活性预测与相互验证,筛选出活性可能较高的6个化合物。该研究可为高效亚胺类杀菌剂的研制提供理论指导。     

芥末精油对锯谷盗成虫的生物活性

本文研究了芥末精油对锯谷盗Oryzaephilus surinamensis成虫的室内杀虫活性.结果表明,芥末精油对锯谷盗成虫具有很强的熏蒸、驱避和触杀活性.在不同时间0.1μL·L-1芥末精油的熏蒸活性均最强,24h熏蒸毒力最大,锯谷盗成虫的校正死亡率达99.38%;方差分析表明不同处理时间和不同处理剂量对试虫的熏蒸活性均有极显著影响.随着时间延长,驱避作用逐渐增强;同一时间处理浓度越高驱避作用越强,8d时0.1μL·L-1驱避活性最强,达100%.在同一时间随着处理浓度的增大,芥末精油对锯谷盗触杀校正死亡率呈上升趋势,但18h后各处理间校正死亡率无显著差异.     

黄皮新肉桂酰胺B对柑橘全爪螨 Panonychus citri的生物活性

为探究黄皮新肉桂酰胺B对柑橘全爪螨Panonychus citri的生物活性,分别采用载玻片浸渍法、叶片残毒法和叶圆片法研究了黄皮新肉桂酰胺B对柑橘全爪螨雌成螨及其卵的触杀活性和驱避作用。结果表明,黄皮新肉桂酰胺B对柑橘全爪螨雌成螨及其卵具有较强的触杀活性,在10~500μg/m L浓度范围内,对柑橘全爪螨雌成螨处理24 h的LC50和LC90分别为62.92μg/m L和346.02μg/m L,其触杀毒力分别是鱼藤酮的3.7和5.4倍、印楝素的3.2和8.1倍;在100μg/m L时杀卵活性达到了42.9%,优于同浓度的鱼藤酮和印楝素;在100μg/m L和500μg/m L浓度下,处理36 h时对柑橘全爪螨的驱避率均大于80.0%,与同浓度的鱼藤酮和印楝素相当。表明黄皮新肉桂酰胺B对柑橘全爪螨具有较好的触杀、驱避作用,可作为杀螨活性的先导化合物。     

滇杨挥发物成分对马铃薯块茎蛾产卵选择的影响

为了筛选非寄主植物滇杨的挥发物中驱避马铃薯块茎蛾产卵的活性成分,在室内利用选择性产卵试验方法分别测定了8种挥发物:丁香酚、苯甲酸、苯甲醇、苯乙醇、2-羟基苯甲醛、β-紫罗兰酮、水杨酸甲酯、苯甲醛不同浓度(0.75~12mg/L)的溶液对马铃薯块茎蛾产卵选择的影响。结果表明:水杨酸甲酯在6~12mg/L浓度范围内对马铃薯块茎蛾产卵有极显著的引诱效果。丁香酚在3~12mg/L浓度范围内对产卵有驱避效果,12mg/L时的产卵驱避率为62.1%。苯甲酸在1.5~12mg/L浓度范围内对产卵有驱避效果,但各浓度下的产卵驱避率不存在显著差异。12mg/L的苯甲醇和苯乙醇的产卵驱避率分别为12.1%和20.2%。6mg/L和12mg/L的2-羟基苯甲醛的产卵驱避率分别为44.1%和33.2%。β-紫罗兰酮在1.5mg/L浓度时产卵驱避率为30.9%。12mg/L的苯甲醛产卵驱避率为38.5%。本文测试的8种挥发物中有7种在不同浓度范围内表现出显著的产卵驱避效果。     

香泽兰提取物微胶囊剂对小菜蛾产卵驱避作用研究

试验观察了创制的香泽兰提取物微胶囊剂对小菜蛾成虫产卵的驱避作用。室内测试结果表明香泽兰提取物微胶囊剂对小菜蛾产卵具明显的驱避活性,随着使用浓度升高而驱避活性逐渐增强,处理后2d,500～4000mg/kg时小菜蛾着卵量分别降低了67%～91%;随着处理时间延长驱避作用逐渐下降,但持效期较长,处理6d后2000mg/kg驱避效果仍可达到84%。田间使用香泽兰提取物微胶囊剂防治小菜蛾产卵的驱避作用好、持效期长,使用8d后各浓度效果均可达到80%以上,最高可达94%。     

新型2-烷氧基取代苯甲酸香叶酯类蚜虫报警信息素类似物的设计、合成及生物活性

为了发现结构新颖的蚜虫行为控制剂,以课题组发现的高活性化合物 3e (2-羟基-3-甲氧基苯甲酸香叶酯)为先导,利用活性亚结构拼接的方法,设计合成了15个未见文献报道的新型2-烷氧基取代苯甲酸香叶酯类蚜虫报警信息素(E)-β-farnesene (EβF)衍生物,其结构经过核磁共振氢谱(1H NMR)、红外光谱(IR)和高分辨质谱(HRMS)的确证。蚜虫驱避活性测定结果表明,部分目标化合物在5 μg剂量下对豌豆蚜Acyrthosiphon pisum表现出不同程度的驱避活性,其中化合物 6i 活性最高,驱避率达到60.9%,与先导化合物 3e 的活性没有显著性差异。靶标蛋白结合实验证明,部分目标化合物与气味结合蛋白ApisOBP9具有较好的结合活性,尤其是化合物 6i 与ApisOBP9的结合常数达到(4.92±0.18) μmol/L。进一步的分子对接结果表明, 6i 与靶标ApisOBP9具有较好的结合作用力,能很好地结合到靶标蛋白的活性位点,其结合模式和先导化合物相似。本研究对后续化合物的结构优化具有重要参考价值。     

甘菊挥发油化学组成及其对烟草甲与赤拟谷盗的杀虫活性

本试验研究了甘菊挥发油的化学组成及其对烟草甲和赤拟谷盗两种常见仓储害虫成虫的熏蒸、触杀和驱避作用。采用水蒸气蒸馏法提取挥发油,GC/MS法分析挥发油的成分及其相对含量。结果表明,从甘菊挥发油中鉴定出了31种化合物,主要组分为樟脑(29.99%)、桉叶油醇(16.87%)、β-水芹烯(4.63%)、顺马鞭草烯醇(4.41%)和顺-β-松油醇(4.04%);生物活性测试结果显示,甘菊挥发油对烟草甲和赤拟谷盗具有一定的触杀活性(LD_(50)分别为24.09μg/头和49.95μg/头)和熏蒸活性(LC_(50)分别为28.67 mg/L和14.40 mg/L)。同时,甘菊挥发油对赤拟谷盗表现出显著的驱避活性,对烟草甲驱避效果不明显。本试验首次研究了我国菊科菊属植物甘菊的挥发油的化学组成和杀虫活性,结果提示该挥发油对烟草甲和赤拟谷盗具有一定杀虫、驱避活性和防治潜力。     

庚醛与桉叶油醇组合对马铃薯块茎蛾产卵选择的影响

马铃薯块茎蛾(Phthorimaea operculella)是世界上为害马铃薯最严重的害虫之一,本研究利用桉叶油醇与庚醛驱避-引诱组合对其产卵行为进行调控,以探究最佳驱避-引诱组合规律及影响因素。在室内条件(27±1℃,L∥D=14h∥10h,RH:50%~70%)测定了桉叶油醇与庚醛单组分及两种组分驱避-引诱组合对马铃薯块茎蛾产卵选择的影响。桉叶油醇在6~12mg/L浓度范围内对马铃薯块茎蛾表现为产卵引诱作用,在18~30mg/L浓度范围内则表现为产卵驱避作用;庚醛在6~30mg/L浓度范围内对马铃薯块茎蛾表现为产卵驱避效果。将对马铃薯块茎蛾产卵行为引诱效果较好的桉叶油醇(3,6,12 mg/L)与驱避效果较好的庚醛(12,18,24mg/L)进行引诱-驱避组合,12mg/L庚醛与3mg/L桉叶油醇push-pull组合效果最好,push-pull效应达36.6%。对马铃薯块茎蛾产卵行为调控最佳的驱避-引诱组合为最低驱避浓度(12mg/L庚醛)与最低引诱(3mg/L桉叶油醇)浓度组合。产卵选择指数和push-pull效应与交配率、单雌产卵量不具有相关性,但是浓度变化可以导致交配率和单雌产卵量的变化。     

Receptor-binding affinity and larvicidal activity of tetrahydroquinoline-type ecdysone agonists against Aedes albopictus

Tetrahydroquinolines (THQs), a class of nonsteroidal ecdysone agonists, are good candidates for novel mosquito control agents because they specifically bind to mosquito ecdysone receptors (EcRs). We have recently performed quantitative structure–activity relationship (QSAR) analyses of THQs to elucidate the physicochemical properties important for the ligand–receptor interaction. Based on previous QSAR results, here, we newly synthesized 15 THQ analogs with a heteroaryl group at the acyl moiety and evaluated their binding affinity against Aedes albopictus EcRs. We also measured the larvicidal activity of the combined set of previously and newly synthesized compounds against A. albopictus to examine the contribution of receptor-binding to larvicidal activity. Multiple regression analyses showed that the binding affinity and the molecular hydrophobicity of THQs are the key determinants of their larvicidal activity.     

Larvicidal and oviposition‐altering activity of monoterpenoids,trans‐anithole and rosemary oil to the yellow fever mosquito Aedes aegypti (Diptera: Culicidae)

BACKGROUND: Aedes aegypti L. is the major vector of dengue fever and dengue hemorrhagic fever. In an effort to find effective tools for control programs to reduce mosquito populations, the authors assessed the acute toxicities of 14 monoterpenoids, trans‐anithole and the essential oil of rosemary against different larval stages of Ae. aegypti. The potential for piperonyl butoxide (PBO) to act as a synergist for these compounds to increase larvicidal activity was also examined, and the oviposition response of gravid Ae. aegypti females to substrates containing these compounds was evaluated in behavioral bioassays. RESULTS: Pulegone, thymol, eugenol, trans‐anithole, rosemary oil and citronellal showed high larvicidal activity against all larval stages of Ae. aegypti (LC₅₀ values 10.3–40.8 mg L^?1). The addition of PBO significantly increased the larvicidal activity of all test compounds (3–250‐fold). Eugenol, citronellal, thymol, pulegone, rosemary oil and cymene showed oviposition deterrent and/or repellent activities, while the presence of borneol, camphor and β‐pinene increased the number of eggs laid in test containers. CONCLUSIONS: This study quantified the lethal and sublethal effects of several phytochemical compounds against all larval stages of Aedes aegypti, providing information that ultimately may have potential in mosquito control programs through acute toxicity and/or the ability to alter reproductive behaviors. Copyright © 2008 Society of Chemical Industry     

Acylated 1,3-Aminopropanols as Repellents against Bloodsucking Arthropods

Starting from a set of known repellent compounds, a general structural framework with high probability for repellent activity was developed by molecular modelling techniques. Synthesis, structure–biological activity relationships of acylated 1,3-aminopropanols on the yellow fever mosquito Aedes aegypti and the properties and activity of the new development candidate compound KBR 3023 on Ae. aegypti, the malaria mosquito Anopheles stephensi, the common house mosquito Culex quinquefasciatus and the stable fly Stomoxys calcitrans are described. The sensory effect of KBR 3023 and deet has been studied in behavioural and neurophysiological investigations on Ae. aegypti and the American cockroach Periplaneta americana. The compounds clearly reduce or even eliminate the approach behaviour towards attractants like host odours or sexual pheromones. Electrophysiological studies on the insects' olfactory receptor organs reveal that certain cell types, which are not involved in perception of the attractive odorants, respond to deet and/or KBR 3023. As soon as one of the compounds is presented together with an attractant, a new input is active in the brain, which adds to the input from other receptors activated by the attractant. This new overall pattern clearly differs from that elicited by the attractant, so that the insect is no longer able to detect the latter. The specificity and mode of action of KBR 3023 was investigated by experiments exploring second-messenger responses elicited in antennal preparations of male P. americana. KBR 3023 induced a rapid increase in the concentration of inositol triphosphate in a dose-dependent and tissue-specific manner; other second-messenger systems were not affected. These observations suggest that KBR 3023 may act via subsets of G-protein-coupled receptors in sensory neurones.     

Quantitative structure–activity studies of insect growth regulators: XVI. Substituent effects of dibenzoylhydrazines on the insecticidal activity to Colorado potato beetle Leptinotarsa decemlineata

Insecticidal activity against the Colorado potato beetle, Leptinotarsa decemlineata, was measured for a series of substituted N-tert-butyl-dibenzoylhydrazines, in which one of the benzoyl moieties closer to the tert-butyl group was fixed as being 2-chloro-substitued and the other variously substituted singly or doubly. The effects of substituents on the activity were quantitatively analysed using the classical quantitative structure–activity relationship (QSAR) procedure. The activity against the Colorado potato beetle increases with the molecular hydrophobicity. In addition, various types of steric effect are at work, depending upon the positions. Hydrogen-bonding acceptor substituents at the para position enhance the activity. There seem to be threshold (or optimum) values, albeit position-dependent, in the molecular hydrophobicity, above which the activity starts to decrease. This biphasic contribution of the molecular hydrophobicity to activity against coleopterous larvae is the most conspicuous difference in substituent effects from those found for similar compounds against lepidopterous pest insects, and may be the basis of the variations in the activity spectrum for certain compounds in this series. The introduction of bulkier substituents into the meta- and para-positions of the benzene ring, apart from the tert-butyl group, is unfavorable to activity. LD₅₀ values against Colorado potato beetle larvae of methoxyfenozide (RH-2485) and tebufenozide (RH-5992) were in the order of 10⁻⁷ mol per insect, whereas those of RH-5849, and halofenozide (RH-0345) were very low, 10⁻⁹–10⁻¹⁰ mol per insect being selective to the coleopterous larvae. © 1999 Society of Chemical Industry     

基于室内高光谱数据的多种类型土壤有机质估算模型比较

基于高光谱数据的土壤有机质反演是土壤遥感及精准农业的重要研究内容,然而不同的光谱处理及建模方法使得模型的估算能力及精度差异明显,限制了模型之间的通用性。为了构建陕西省土壤有机质含量估算的最优模型,以陕西省9种主要土壤类型的216个土样的光谱反射曲线和土壤有机质含量为数据基础,将光谱反射曲线进行一阶微分d(R)、倒数对数log(1/R)、倒数对数一阶微分d[log(1/R)]和包络线去除N(R)4种变换,结合一元线性回归(SLR)、偏最小二乘回归(PLSR)和支持向量机回归(SVR)3种建模方法构建了不同的土壤有机质含量估算模型。结果显示:不同类型土壤的反射光谱曲线总体态势基本一致,吸收特征位置基本相同,且土壤有机质含量与光谱反射率呈负相关态势;基于d [log(1/R)]光谱变换构建的SVR估算模型精度最高,建模集和验证集的判断系数(R~2)分别为0.9210、0.8874,验证均方根误差(RMSE)为2.18,相对分析误差(RPD)达到2.8751,是估算陕西省土壤有机质含量的最优模型,PLSR次之,SLR最差。