Beijing Advanced Innovation Centre for Food Nutrition and Human Health, Department of Applied Chemistry, China Agricultural University, No. 2 West Yuanmingyuan Road, Beijing, 100193, PR China.
Beijing Advanced Innovation Centre for Food Nutrition and Human Health, Department of Applied Chemistry, China Agricultural University, No. 2 West Yuanmingyuan Road, Beijing, 100193, PR China.
Environ Pollut. 2019 Jan;244:757-765. doi: 10.1016/j.envpol.2018.10.056. Epub 2018 Oct 15.
Insecticide ethiprole, the alternative of fipronil which has been restricted in many countries, may contaminant water bodies through surface runoff after agricultural application, however, the aquatic toxicity and environmental behavior of ethiprole is still unknown. In this study, five metabolites of ethiprole (ethiprole sulfone, ethiprole sulfide, ethiprole amide, desethylsulfinyl ethiprole and ethiprole sulfone amide) were synthesized and their toxic effects on photosynthetic pigment and antioxidase in aquatic plant Chlorella pyrenoidosa (C. pyrenoidosa) were evaluated on an enantiomeric level. Besides, the accumulation and metabolism of rac-ethiprole and its enantiomers in algae suspension and algae were studied. Ethiprole sulfide was found to be more toxic than ethiprole, with the 96h EC value seven times lower than ethiprole. Enantioselective toxicity was observed with R-ethiprole more toxic than S-ethiprole. The contents of chlorophyll were significantly reduced by all the chemicals at higher concentrations, and the levels of protein, malondialdehyde (MDA) and the activity of antioxidant defense enzymes were dose-dependent. The half-life of rac-ethiprole in algae suspension was 13.6 days and ethiprole amide was the major metabolite. However, ethiprole sulfide was the main metabolite in algae, suggesting different metabolic pathways in algae suspension and algae. Enantioselective metabolism in algae suspension was found with S-ethiprole metabolized faster than R-ethiprole. The preferentially accumulated and metabolized of R-ethiprole in algae was observed and C. pyrenoidosa had limited capacity to convert one enantiomer into the other. These findings indicated the toxicity of ethiprole to C. pyrenoidosa is lower than fipronil. The individual enantiomers of chiral pollutants and their metabolites should be considered in risk assessments.
杀虫剂乙虫腈是已在许多国家受到限制的氟虫腈的替代品，它可能会在农业应用后通过地表径流污染水体，然而，乙虫腈的水生毒性和环境行为仍不清楚。在这项研究中，合成了乙虫腈的五种代谢物（乙虫腈砜、乙虫腈硫醚、乙虫腈酰胺、去乙基砜基乙虫腈和乙虫腈砜酰胺），并在对映体水平上评估了它们对水生植物蛋白核小球藻（Chlorella pyrenoidosa，C. pyrenoidosa）的光合色素和抗氧化酶的毒性作用。此外，还研究了 rac-乙虫腈及其对映体在藻类悬浮液和藻类中的积累和代谢。乙虫腈硫醚比乙虫腈毒性更大，其 96hEC 值比乙虫腈低 7 倍。对映体选择性毒性观察到 R-乙虫腈比 S-乙虫腈毒性更大。所有化学物质在较高浓度下均显著降低叶绿素含量，蛋白质、丙二醛（MDA）和抗氧化防御酶活性呈剂量依赖性。rac-乙虫腈在藻类悬浮液中的半衰期为 13.6 天，主要代谢物为乙虫腈酰胺。然而，乙虫腈硫醚是藻类中的主要代谢物，表明藻类悬浮液和藻类中的代谢途径不同。在藻类悬浮液中发现对映体选择性代谢，S-乙虫腈的代谢速度比 R-乙虫腈快。观察到 R-乙虫腈在藻类中的优先积累和代谢，并且小球藻将一种对映体转化为另一种对映体的能力有限。这些发现表明乙虫腈对小球藻的毒性低于氟虫腈。在风险评估中应考虑手性污染物及其代谢物的单个对映体。
