Discovery of Rhodanine Inhibitors Targeting <i>Of</i> ChtI Based on the π-Stacking Effect and Aqueous Solubility
Qing Han, Nan Wu, Jingyu Zhang, Tianyu Feng, Yunjiang Zi, Rulei Zhang, Renxuan Zou, Yaoyang Liu, Qing Yang, Hongxia Duan
Abstract
The application of some reported inhibitors against the chitinolytic enzyme Of ChtI was limited due to their unsatisfactory insecticidal activities. Hence, we first performed a synergetic design strategy combining the π-stacking effect with aqueous solubility to find novel rhodanine analogues with inhibitory activities against Of ChtI. Novel rhodanine compounds IAa–f and IBa–f have weak aqueous solubility, but they ( IAd: K i = 4.0 μM; IBd: K i = 2.2 μM) showed better inhibitory activities against Of ChtI and comparable insecticidal efficiency toward Ostrinia furnacalis compared to the high aqueous solubility compounds IIAa–f and IIBa–f ( IIAd: K i = 21.6 μM; IIBd: K i = 14.3 μM) without a large conjugate plane. Further optimized compounds IIIAa–j with a conjugate plane as well as a higher aqueous solubility exhibited similar good inhibitory activities against Of ChtI ( IIIAe: K i = 2.4 μM) and better insecticidal potency ( IIIAe: mortality rate of 63.33%) compared to compounds IAa–f and IBa–f, respectively. Molecular docking studies indicated that the conjugate planarity with the π-stacking effect for rhodanine analogues is responsible for their enzyme inhibitory activity against Of ChtI. This study provides a new strategy for designing insect chitinolytic enzyme inhibitors as insect growth regulators for pest control.