Enantioselective toxicity of metolachlor to Scenedesmus obliquus in the presence of cyclodextrins.
Enantioselective toxicity of metolachlor to Scenedesmus obliquus in the presence of cyclodextrins.
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DOI：
10.1002/chir.21981
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发表时间：
2012-02
期刊：
影响因子：
2
通讯作者：
Hui J. Liu;Weidan Cai;Ruo N Huang;H. Xia;Yuezhong Wen
中科院分区：
文献类型：
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作者：
Hui J. Liu;Weidan Cai;Ruo N Huang;H. Xia;Yuezhong Wen
环糊精(CD)具有多种手性中心，能够通过形成包合物识别对映体分子。通过急性毒性试验，研究了异丙甲草胺(α-α)及其S对映体(S-异丙甲草胺)对斜生栅藻的对映体选择性生态毒性，并以β-环糊精(β-CD)和异丙甲草胺-环糊精(RAC-CD)为研究对象。结果表明，S-异丙甲草胺的水生毒性高于敌草胺-异丙甲草胺，而镉是通过增强异丙甲草胺的水生毒性而不是S-异丙甲草胺对斜纹夜蛾的水生毒性来增强异丙甲草胺的对映选择性。RAc-异丙甲草胺-Cd络合物的平衡常数大于S-异丙甲草胺-Cd络合物的平衡常数，这是RAc-异丙甲草胺具有更大的水毒性转移效应的原因。Cd络合物的热力学研究表明，所有络合物的包合作用主要是一个自发的、热焓驱动的过程。这些结果将有助于了解CDS转移异丙甲草胺水生毒性的初步机理以及CDS介导的异丙甲草胺的环境过程，从而正确地将CDS应用于手性农药的配制和手性污染物的环境修复。
Cyclodextrins (CDs) possess a variety of chiral centers and are capable of recognizing enantiomeric molecules through the formation of inclusion complexes. Two types of CDs, α-cyclodextrin (α-CD) and β-cyclodextrin (β-CD), were selected to evaluate the effects of the enantioselective ecotoxicity of racemic metolachlor (Rac-metolachlor) and its S-enantiomer (S-metolachlor) on the freshwater algae Scenedesmus obliquus (S. obliquus) by acute toxicity test. The results showed that the aquatic toxicity of S-metolachlor was higher than Rac-metolachlor and that CDs enhanced the toxicity of metolachlor enantioselectively by increasing the aquatic toxicity of Rac-metolachlor rather than that of S-metolachlor to S. obliquus. The equilibrium constant for Rac-metolachlor-CD complexes was higher than that of S-metolachlor-CDs, which was responsible for the greater aquatic toxicity shift effect of Rac-metolachlor. Thermodynamic studies of CD complexes showed that inclusion for all of the complexes was primarily a spontaneous, enthalpy-driven process. These results will help to understand the preliminary mechanism of shifting aquatic toxicity of metolachlor by CDs and the CDs mediated environmental processes of metolachlor, to correctly apply CDs to chiral pesticides formulation and environmental remediation of chiral contaminants.