Lv Xiaotian, Liu Chen, Li Yaobin, Gao Yongxin, Guo Baoyuan, Wang Huili, Li Jianzhong
Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing, China.
Chirality. 2013 Dec;25(12):890-6. doi: 10.1002/chir.22230. Epub 2013 Sep 7.
The bioaccumulation and excretion of enantiomers of myclobutanil in Tenebrio molitor larvae through dietary exposure under laboratory conditions were investigated using high-performance liquid chromatography tandem mass spectrometry (HPLC-MS/MS) based on a ChiralcelOD-3R [cellulosetris-tris-(3, 5-dichlorophenyl-carbamate)] column. The wheat bran fed to Tenebrio molitor larvae was spiked with racemic myclobutanil at two dose levels of 20 mg/kg and 2 mg/kg (dry weight). The results showed that there was a significant trend of enantioselective bioaccumulation in the larvae with a preferential accumulation of (-)-myclobutanil in 20 mg/kg dose exposure, but it was not obviously observed in the 2 mg/kg dose group. A kinetic model considering enantiomerization between the two enantiomers based on first-order reactions was built and the rate constants were estimated to discuss the kinetic reason for the different concentrations of individual enantiomers in the larvae. The approximations implied an inversion between the two enantiomers with a relatively higher rate of the inversion from (-)-myclobutanil to (+)-myclobutanil. Meanwhile, analysis of data of excretion samples suggested the active excretion is probably an important pathway for the insect to eliminate myclobutanil rapidly with nonenantioselectivity as a passive transport process, which was consistent with the low accumulation efficiency of myclobutanil measured by BAF (bioaccumulation factor).
在实验室条件下，通过饮食暴露，利用基于手性纤维素OD-3R[纤维素三（3,5-二氯苯基-氨基甲酸酯）]柱的高效液相色谱串联质谱法（HPLC-MS/MS），研究了腈菌唑对映体在黄粉虫幼虫中的生物累积和排泄情况。喂食黄粉虫幼虫的麦麸添加了外消旋腈菌唑，剂量水平分别为20mg/kg和2mg/kg（干重）。结果表明，在20mg/kg剂量暴露下，幼虫中存在对映体选择性生物累积的显著趋势，优先累积（-）-腈菌唑，但在2mg/kg剂量组中未明显观察到。建立了基于一级反应考虑两种对映体之间对映异构化的动力学模型，并估算了速率常数，以探讨幼虫中单个对映体浓度不同的动力学原因。近似结果表明两种对映体之间存在转化，从（-）-腈菌唑到（+）-腈菌唑的转化速率相对较高。同时，排泄样品数据分析表明，主动排泄可能是昆虫快速消除腈菌唑的重要途径，作为被动运输过程，不存在对映体选择性，这与通过生物累积因子（BAF）测得的腈菌唑低累积效率一致。
