【作者】 申志刚；

【导师】 周志强； 刘东晖；

【作者基本信息】 中国农业大学 ， 农药学， 2014， 博士

【摘要】 本文以动物模型作为研究对象,研究了手性农药在动物中的选择性代谢行为,并对选择性代谢的机理进行了探讨。实验中利用大鼠肝微粒体代谢体系研究了手性农药戊唑醇、己唑醇的选择性降解行为并测定了其对大鼠原代肝细胞的毒性。对戊唑醇的研究结果显示其外消旋体以及单体的代谢均符合一级动力学。外消旋体(15μmol L-1的降解过程中,两单体代谢速率有较大差异,S体半衰期为22.35min,R体半衰期为48.80min。但是单体降解过程(7.5μmol L-1)的两单体的降解速率无显著差异。研究发现戊唑醇单体之间存在竞争性抑制作用,IC50S/R为9.67μmol L-1,而IC50R/S为48.12μmol L-1。单体间相互抑制程度不同造成在外消旋体降解过程中单体的代谢速率的差异,导致这一差异的原因为对映体与代谢酶的结合常数存在差异。对己唑醇在来自不同性别的大鼠肝微粒体中的代谢研究表明其外消旋体以及单体在肝微粒体中的降解过程均符合一级动力学,并且对映体之间的代谢速率存在显著差异,(+)-己唑醇代谢较快。己唑醇在雄性大鼠微粒体中的代谢速率高于在雌性大鼠中的代谢速率。通过抑制试验表明导致性别差异的原因为相关代谢酶的性别差异。而通过测定戊唑醇与己畔醇对原代大鼠肝细胞的毒性发现外消旋体与对映体单体对细胞的急性毒性存在差异。以雄性和雌性家兔为试验动物研究了粉唑醇对映体的药代动力学及在各组织中的残留。实验采用耳静脉给药的方式注射粉唑醇外消旋体(5.0mgkg-1b.w.)。研究发现,对于两种性别,给药后前期血浆中S-粉唑醇含量高于其对映体,但随时间增长其含量逐渐低于R体。药物与血浆蛋白结合的选择性差异导致了分布速率不同。药代动力学参数反映了粉唑醇两对映体在家兔体内代谢、分布及消除上均存在差异,并且存在性别差异。实验研究了经口一次暴露以及长期暴露后alpha-六六六(α-HCH)在蛋鸡体内的消解以及分布。结果显示蛋鸡对α-HCH的吸收与分布过程十分迅速,分布半衰期为0.92h,排泄过程是造成蛋鸡体内α-HCH偏离外消旋的重要因素。实验中采用了自制的有机改性蒙脱土作为吸附剂吸附饲料中的α-HCH,结果显示改性蒙脱土可以有效地减少蛋鸡通过饲料吸收的α-HCH,从而可以降低相关产品中α-HCH的含量,进而保证食品安全。在研究氯氰菊酯在蛋鸡体内的代谢时,发现α-氯氰菊酯在提取及检测过程中容易发生异构化现象造成测定结果不准确。针对这一问题,利用GC-ECD开发了保持构型稳定的对α-氯氰菊酯及其主要酸性代谢物同时检测的残留分析方法,并对实际样本进行了检测。结果显示本方法有较好的精密度,平行性好。同时样品中的α-CP异构化率较低,准确度较高。在此方法的基础上,对蛋鸡经口暴露α-氯氰菊酯后的血浆中α-氯氰菊酯以及代谢物进行了分析,结果显示α-氯氰菊酯主要在血浆中分布,代谢物顺式菊酸的浓度在血浆中较高,实验过程中未发现反式菊酸。由于蒙脱土具有良好的吸附能力,通过对蒙脱土进行改性,制备成了一种新型的磁固相吸附材料,并将其成功的应用于水中三唑类农药的分析。基于磁性分离技术开发的低密度磁流体液相微萃取方法提出了新的相分离以及萃取剂回收方法,简化了密度比水小的轻萃取剂的回收过程,提高了方法易用性,并将方法应用到实际样本的分析,得到了较好的实验结果。更多还原

【Abstract】 In this paper, we investigated the metabolism of the chiral pesticides in animal models.The enantioselective disappearance of tebuconazole and hexaconazole were incestigated in rat liver microsomes system and the cytotoxicity to the rat primary hepatocytes were determinedby the MTT assay. The degradation of rac-tebuconazole and the enantiomer followed first-order kinetics. The result demonstrated that rac-tebuconazole (15μmol L-1) degradation in vitro assay was selective, but no significant difference between the enantiomers was found in the respective incubation (7.5μmol L-1for each). The interaction results revealed that there was competitive inhibition between S-and R-form, and the inhibition was a significant difference. This means that the interaction effect between the two enantiomers contributed to the selective degradation in the rat liver microsomes. The metabolism rate of hexaconazole in male and female rat hepatic microsomes was enantioselective and the degradation rate of hexaconazole metabolism in male rat hepatic microsomes was faster than that in female. The inhibition experiments with CYP inhibitors showed that the inhibitory effect of inhibitors was enantioselective and affected by sex, suggesting that the enantioselective metabolism of hexaconazole was determined by the amount of hepatic cytochrome P450and the expression of individual isoforms of CYPs.The enantioselective pharmacokinetics and degradation of flutriafol enantiomers in rabbits were investigated by a single ear intravenous (i.v.) administration at doses of5.0mgkg-1b.w. of racemate. At the beginning the concentration of S-flutriafol in plasma was higher than its antipide, but it became lower than its antipide gone with time. The protein binding was an important factor in modulating the disposition of flutriafol. The pharmacokinetic parameters showed that the metabolism, distribution and elimination were gender-related and stereoselective.The enantioselective metabolism, distribution and elimination of alpha-HCH in hens were studied through the oral route. The results showed that processes of the absorption and distribution were quickly and the excretion process was one of the important causes of the stereoselectivity. The organic modified montmorillonite showed a good adsorption capacity to alpha-HCH and used as feed additive to reduce the alpha-HCH uptake.An analysis method was developed to analyse a-cypermethrin and its main acid metabolites. In this method, the isomerization of a-cypermethrin was reduced to an acceptable level. This method was very sensitive for the quantitative determination of a-CP and its major acid metabolites in animal foods.Baesed on this method, the behavior of a-CP in the plasma of hens after oral exposure. The results showed that the a-CP was mainly distributed in plasma and only cis-DCVA was detected in the experiment.Two novel pretreatment methods was developed based on the magnetic separation technology. First we a prepared a new magnetic material based on montmorillonite (MMT) through a two-step reaction. In this work, a MSPE method was developed for the extraction of five triazole pesticides residues in water samples to evaluate the applicability of this new material. The second method was low-density magnetofluid dispersive liquid-liquid microex-traction. Comparing with the existing low density solvents micro-extractionmethods, no special devices and complicated operations were required during the whole extraction process. Under the optimal extraction condition, the two novel pretreatment methods offered good LOD, as well as good linearity and acceptable repeatability.更多还原