Enantioselective Degradation and Bioactivity Mechanism of a New Chiral Fungicide Fluindapyr in Paddy Ecosystems.

Fluindapyr is a novel chiral succinate dehydrogenase inhibitor used to control fungal diseases. The enantioselective effects of fluindapyr in paddy ecosystems are unknown. We developed a new chiral determination method of fluindapyr using ultrahigh performance liquid chromatography tandem mass spectrometry. The absolute configuration of the fluindapyr enantiomers was identified by an electron circular dichroism model. A new husk-based biochar material was used to optimize and establish a QuEchERs method for paddy soil determination. Under anaerobic conditions, the half-lives of R -fluindapyr and S -fluindapyr in paddy soil were 69.6 and 101.8 days, respectively. R -fluindapyr degraded more rapidly than S -fluindapyr. S -fluindapyr was 87.8 times more active against Rhizoctonia solani than R -fluindapyr. The enantioselective bioactivity mechanism was illustrated by molecular docking between the fluindapyr enantiomers and SDH of R. solani . The binding powers of R -fluindapyr and S -fluindapyr to proteins were -32.12 and - 42.91 kcal/mol, respectively. This study reports the stereoselectivity of fluindapyr about determination, degradation, bioactivity, and its mechanism. It provides a foundation for an in-depth study of fluindapyr at the enantiomer level.