Design of Inhibitors Targeting Chitin-Degrading Enzymes by Bioisostere Substitutions and Scaffold Hopping for Selective Control of Ostrinia furnacalis

Chitin-degrading enzymes are critical components in regulating the molting process of the Asian corn borer and serve as potential targets for controlling this destructive pest of maize. Here, we used a scaffold-hopping strategy to design a series of efficient naphthylimide insecticides. Among them, compound 8c exhibited potent inhibition of chitinase from OfChi-h and OfChtI at low nanomolar concentrations (IC50 = 1.51 and 9.21 nM, respectively). Molecular docking simulations suggested that 8c binds to chitinase by mimicking the interaction of chitin oligosaccharide substrates with chitinase. At a low concentration of 100,000 ppm, compound 8c performed comparably to commercial insecticides in controlling the highly destructive plant pest, the Asian corn borer. Tests on a wide range of nontarget organisms indicate that compound 8c has very low toxicity. In addition, the effect of inhibitor treatment on the expression of genes associated with the Asian corn borer chitin-degrading enzymes was further investigated by quantitative real-time polymerase chain reaction. In conclusion, our study highlights the potential of 8c as a novel chitinase-targeting insecticide for effective control of the Asian corn borer, providing a promising solution in the quest for sustainable pest management.