Modification of Azo-Aminopyrimidines as Potent Multitarget Inhibitors of Insect Chitinolytic Enzymes O<i>f</i>Chi-h and O<i>f</i>Hex1

Multitarget inhibitors exhibit significant advantages in reducing the risk of drug resistance, enhancing therapeutic efficacy, and minimizing dosage, outperforming multicomponent combination drugs. On the basis of glycoside hydrolase family 18 (GH18) chitinases and GH20 β-<i>N</i>-acetylhexosaminidase using the same substrate-assisted catalytic mechanism and similar substrate binding modes, a series of novel azo-aminopyrimidine compounds have been designed and synthesized as multitarget inhibitors targeting chitinolytic enzymes O<i>f</i>Chi-h and O<i>f</i>Hex1. Compounds <b>AAP4</b> (O<i>f</i>Chi-h, <i>K</i>_i = 29.3 nM; O<i>f</i>Hex1, <i>K</i>_i = 4.9 μM) and <b>AAP16</b> (O<i>f</i>Chi-h, <i>K</i>_i = 32.4 nM; O<i>f</i>Hex1, <i>K</i>_i = 7.2 μM) were identified to be potent multitarget inhibitors of these enzymes, which were predicted to occupy the -1 subsite and engage in H-binding interactions with catalytic residues. <b>AAP4</b> also displayed significant insecticidal activity against lepidopteran pests <i>Ostrinia furnacalis</i> through leaf dipping and pot experiments. In addition, the safety of <b>AAP4</b> to corn and the natural enemy <i>Trichogramma ostriniae</i> was comprehensively evaluated. This present work indicates that azo-aminopyrimidines, as multitarget inhibitors against chitinolytic enzymes, can be further developed as safe and efficient pest control and management agents.