氟唑菌苯胺对蛋白核小球藻的立体选择性毒性效应

为了探究氟唑菌苯胺对水生生物的立体选择性毒性效应，测定了氟唑菌苯胺对映体对蛋白核小球藻的急性毒性以及光合色素含量的影响。结果表明，S-氟唑菌苯胺对蛋白核小球藻具有更高的急性毒性，是R-氟唑菌苯胺1.2倍。高剂量暴露浓度下，S-氟唑菌苯胺对小球藻叶绿素a、叶绿素b、类胡萝卜素生物合成的抑制率分别为35%、28%、37%，是R-对映体的2.1、1.9、2.8倍，表明氟唑菌苯胺对蛋白核小球藻的立体选择性急性毒性可能是由于对映体对光合色素生物合成抑制差异造成的。降解实验结果表明低毒对映体R-氟唑菌苯胺被优先降解，第7天时R-氟唑菌苯胺和S-氟唑菌苯胺降解率分别为82.5%和65.8%，EF值为0.12，且对映体构型稳定。研究结果为氟唑菌苯胺水生生态风险评价提供数据支撑，同时为手性农药立体选择性机制研究提供新的思路。

Stereoselective toxic effects of penflufen against Chlorella pyrenoidosa

The acute toxicity of penflufen enantiomers and the effects of photosynthetic pigment content to Chlorella pyrenoidosa were measured to investigate the stereoselective toxic effect for aquatic organism. The results showed that the EC₅₀ of S-penflufen to C. pyrenoidosa was 1.2 times that of R-penflufen, indicating that acute toxicity of S-penflufen was higher than that of R-penflufen. At the high exposure concentration, the inhibition rates of S-penflufen on the biosynthesis of chlorophyll A, chlorophyll B, and carotene were 35%, 28% and 37%, respectively, which were 2.1, 1.9 and 2.8 times that of R-penflufen. These results suggested that the enantioselective acute toxicity of penflufen to C. pyrenoidosa might be caused by the difference in the inhibition of biosynthesis of photosynthetic pigments by enantiomers. The degradation percentages of R-penflufen and S-penflufen at 7 d were 82.5% and 65.8%, respectively, suggesting that the low toxic R-penflufen preferred to be degraded with the enantiomer fraction value of 0.12. In addition, the configuration of penflufen enantiomer was stable. These results provide an important basis for the aquatic ecological risk assessment of penflufen and a novel insight into the study of the enantioselective mechanism of chiral pesticides.