Selectivity of chirality isoxazoline insecticides upon GABARs among on‐target and non‐target species via molecular model

Abstract BACKGROUND The target of the isoxazoline insecticides, including fluralaner, fluxametamide, and isocycloseram, was the γ‐aminobutyric acid receptor (GABAR). However, the interaction mechanism between isoxazoline insecticides with different chiral structures and GABAR, as well as the selectivity among on‐target and non‐target species GABARs remains unclear. RESULTS In this study, we integrated homology modeling, molecular dynamics (MD) simulation, molecular docking, and MM‐GBSA calculations to explore the inhibition mechanisms of three isoxazoline insecticides. The MM‐GBSA calculations indicated that the binding affinity between S‐fluralaner with GABAR (−48.43 kcal/mol) was better than that of R‐fluralaner (−36.36 kcal/mol). The analysis of sequence alignment revealed that the key residues in the on‐target species ( Plutella xylostella ), namely Ile223, Leu227, Met261, Asn265, Gly282, and Phe285, were allele to Leu223, Met227, Ser261, Arg265, Ala282, and Tyr285 in the non‐target species ( Danio rerio , Coturnix japonica , and Mus musculus ). Consequently, structural analysis reveals that the GABAR site in the on‐target species exhibits a more cavity depth, expanded surface area, and increased volume compared to non‐target species. These distinctive structural features facilitate enhanced binding affinity with S‐fluralaner, thereby contributing to improved species selectivity. CONCLUSION The computational results revealed that the S‐conformation of isoxazoline insecticides exhibits higher activity than the R‐conformation when binding to GABAR. Notably, S‐fluralaner demonstrated effective binding with GABAR in the target species, whereas no binding affinity was observed in non‐target species. The findings provide a valuable foundation for the future development of novel, safe, and effective GABAR insecticides. © 2025 Society of Chemical Industry.