Lin Kunde, Zhou Shanshan, Xu Chao, Liu Weiping
Research Center of Green Chirality, Zhejiang University of Technology, Hangzhou 310032, China.
J Agric Food Chem. 2006 Oct 18;54(21):8134-8. doi: 10.1021/jf061547l.
Despite the fact that the biological processes of chiral pesticides are enantioselective, the biotoxicity of methamidophos with respect to enantioselectivity has so far received limited research. In this study, the enantiomeric separation and biotoxicity of the two enantiomers of methamidophos were investigated. Successful enantioseparation of methamidophos using high-performance liquid chromatography on a Chiralcel OD column was achieved. As indicated by the optical rotation and circular dichroism detection, (+)-methamidophos was eluted prior to (-)-methamidophos. The t test at the 95% level of confidence indicated significant differences between the enantiomers in their in vitro inhibition toward acetylcholinesterases of bovine erythrocytes and Electrophorus electricus and in vivo acute aquatic toxicity to Daphnia magna. The in vitro assays showed that (-)-methamidophos was about 8.0-12.4 times more potent to the enzymes than its (+)-form. In contrast, the (+)-enantiomer was 7.0 times more toxic to D. magna in 48 h tests. The toxicity of racemic methamidophos was intermediate in both in vitro and in vivo bioassays. These results suggest that the biotoxicity of chiral OPs to nontargeted organisms is enantioselective and therefore should be reevaluated with their pure enantiomers.
尽管手性农药的生物过程具有对映体选择性，但甲胺磷在对映体选择性方面的生物毒性迄今为止研究有限。本研究对甲胺磷两种对映体的对映体分离和生物毒性进行了研究。采用高效液相色谱法在Chiralcel OD柱上成功实现了甲胺磷的对映体分离。旋光和圆二色检测表明，(+)-甲胺磷比(-)-甲胺磷先洗脱。在95%置信水平下的t检验表明，两种对映体对牛红细胞和电鳗乙酰胆碱酯酶的体外抑制作用以及对大型溞的体内急性水生毒性存在显著差异。体外试验表明，(-)-甲胺磷对这些酶的效力比其(+)-异构体高约8.0 - 12.4倍。相反，在48小时试验中，(+)-对映体对大型溞的毒性高7.0倍。外消旋甲胺磷的毒性在体外和体内生物测定中均处于中间水平。这些结果表明，手性有机磷对非靶标生物的生物毒性具有对映体选择性，因此应以其纯对映体重新评估。
