Design, Synthesis, and Biological Assessment of Potent Covalent Inhibitors of Insect UDP- N -acetylglucosamine Pyrophosphorylase

Insect UDP- N -acetylglucosamine pyrophosphorylase (UAP) catalyzes the formation of UDP- N -acetylglucosamine, which is a precursor of chitin synthesis. This makes UAP a promising molecular target for developing green pesticides. Inspired by a Cys 334 -covalent strategy, a series of maleimide derivatives against insect UAP were designed and synthesized. Enzyme activity assays revealed that all tested compounds exhibited potent inhibitory activity. Thereinto, the respective IC 50 were 150 ± 10, 124 ± 26, and 108 ± 20 nM for compounds A5, A10, and A15 against Sf UAP. Furthermore, time-dependent inhibition assays revealed that the IC 50 of A15 decreased to 13.0 nM upon extending the incubation time to 60 min, supporting a time-dependent inhibitory profile; covalent docking simulations further corroborated a covalent binding mechanism. Bioassays demonstrated that A15 significantly inhibited the growth and development of Plutella xylostella, Spodoptera frugiperda, and Spodoptera litura . Overall, this study provides a template for designing more UAP inhibitors with covalent characteristics.