CYP4CE1 Metabolized Nitenpyram through Two Types of Oxidation Reaction, Hydroxylation, and N-Demethylation

Nitenpyram, taking the place of imidacloprid, is a widely used neonicotinoid insecticide to control Nilaparvata lugens in Asia. Two P450s, CYP4CE1 and CYP6ER1, are key factors in the metabolic resistance against nitenpyram and imidacloprid. In this study, we found that CYP4CE1 expression was strongly associated with nitenpyram resistance in 8 field-collected populations, whereas CYP6ER1 expression correlated with imidacloprid resistance. Hence, we focused on nitenpyram metabolism by CYP4CE1, due to that imidacloprid metabolism by CYP6ER1 has intensively investigated. Mass spectrometry analysis revealed that recombinant CYP4CE1 metabolized nitenpyram into three products, N-desmethyl nitenpyram, hydroxy-nitenpyram, and N-desmethyl hydroxy-nitenpyram, with a preference for hydroxylation. In contrast, CYP6ER1 metabolized nitenpyram into a single product, N-desmethyl nitenpyram. These results provide new insights into the specific catalytic mechanisms of P450 enzymes in neonicotinoid metabolism and underscore the importance of different catalytic reactions in neonicotinoid insecticide resistance.