Department of Applied Chemistry, China Agricultural University, Beijing 100193, PR China.
J Hazard Mater. 2011 Sep 15;192(3):1072-8. doi: 10.1016/j.jhazmat.2011.06.010. Epub 2011 Jun 12.
Alpha-cypermethrin, a synthetic pyrethroid, is highly effective against a wide range of chewing and sucking insects in crops, and it is a racemic mixture of two enantiomers ((+)-1R-cis-αS+(-)-1S-cis-αR). Studies about the toxicity of alpha-cypermethrin to non-target organisms are mainly focused on aquatic organisms, whereas information regarding terrestrial organisms is relatively much less. Very little report about its enantioselective toxicity is known, so the present study tested the enantiomer-specific acute toxicity to earthworm Eisenia fetida. Experiment about bioaccumulation of two enantiomers in soil was conducted, peak-shaped accumulation curves were observed for both enantiomers, and the calculated biota to soil accumulations factor (BSAF) have significant difference between the two enantiomers. It was obvious that earthworm can uptake alpha-cypermethrin enantioselectively, preferentially accumulating (-)-(1S-cis-αR)-enantiomer. Great difference in toxicity to earthworm between two enantiomers was found, and the calculated LC(50) values for (+)-(1R-cis-αS)-, (-)-(1S-cis-αR)-, and rac-alpha-cypermethrin were 49.53, 1663.87 and 165.61 ng/cm(2), respectively. The acute toxicity of alpha-cypermethrin enantiomers was enantioselective.
α-氯氰菊酯是一种合成拟除虫菊酯，对作物中的咀嚼式和刺吸式昆虫有高效防治作用，它是两种对映异构体((+)-1R-顺式-αS+(-)-1S-顺式-αR)的外消旋混合物。关于α-氯氰菊酯对非靶标生物的毒性研究主要集中在水生生物上，而关于陆地生物的信息则相对较少。关于其对映体选择性毒性的报道很少，因此本研究测试了α-氯氰菊酯对蚯蚓（赤子爱胜蚓）的对映体特异性急性毒性。进行了两种对映体在土壤中生物累积的实验，观察到两种对映体均呈现峰形累积曲线，并且计算出的生物对土壤的富集因子（BSAF）在两种对映体之间存在显著差异。显然，蚯蚓可以选择性地摄取α-氯氰菊酯，优先积累（-）-（1S-顺式-αR）-对映体。发现两种对映体对蚯蚓的毒性存在显著差异，（+）-（1R-顺式-αS）-、（-）-（1S-顺式-αR）-和 rac-α-氯氰菊酯的 LC（50）值分别为 49.53、1663.87 和 165.61ng/cm（2）。α-氯氰菊酯对映体的急性毒性具有对映体选择性。
