Enantiomer-specific effects of metamifop on serum metabolism in rats

Metamifop (MET) is a widely used pesticides in paddy field and it has good weed control effect. As a chiral pesticide that may be hazardous to human health through food chain transmission, there could be selective differences in the metabolism and toxicity of its enantiomers, so the study of chiral MET may offer an assessment of MET toxicity and stereoselectivity at the enantiomeric level. A total of 39, 43 and 31 differential metabolites were screened from the data sets of Rac-, R-(-)- and S-(+)-MET, respectively. Metabolic pathway analysis revealed that MET and its enantiomers primarily affected sphingolipid metabolism, glycerophospholipid metabolism, linoleic acid metabolism, α-linolenic acid metabolism and arachidonic acid metabolism. Rac- and S-(+)-MET affected the synthesis of glycosylphosphatidylinositol (GPI)-anchored biomolecules. R-(-)- and S-(+)-MET affected glutathione metabolism. R-(-)-MET affected vitamin B6 metabolism, selenium compound metabolism, and steroid biosynthesis. Pyrimidine metabolism was only affected by Rac-MET. The experimental results indicated that MET and its enantiomers may affect the nervous and immune systems in rats. Further inter-group difference analysis also demonstrated stereoselectivity of MET and its enantiomers on rat serum metabolism. These findings may provide more detailed information on the toxicity of Rac-, S-(+)- and R-(-)-MET in rat, as well as some context for assessing the environmental risk of the three agents to organisms.