Modification of\nAzo-Aminopyrimidines as Potent Multitarget\nInhibitors of Insect Chitinolytic Enzymes O<i>f</i>Chi‑h\nand O<i>f</i>Hex1

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