Novel Conjugated 5-Alkenyl Rhodanine Tethered 1,4-Benzodioxane Derivatives as Dual-Chitinases Inhibitors to Hinder the Growth of Asian Corn Borer

Abstract OfChtI and OfChi-h are ideal targets for developing agricultural inhibitors against Ostrinia furnacalis. In order to further confirm the importance of conjugated systems in rhodanine derivatives, sixteen novel 1,4-benzodioxane-tethered-rhodanine derivatives were designed and synthesized with or without C = C double bond of 5-alkenyl rhodanine skeleton. Among them, compounds 3a ~ 3h, with preserved 5-alkenyl rhodanine skeleton, all exhibited much better inhibitory activities against both OfChtI and OfChi-h, compared to that of the corresponding reduced compounds 4a ~ 4h without its C = C double bond. The inhibitory mechanism demonstrated that the 5-alkenyl rhodanine conjugated plane was conducive to improving the binding affinity with both two chitinases. Compound 3g was identified as the most potential dual-chitinases inhibitor against OfChtI (Ki = 2.57µM) and OfChi-h (Ki = 2.03µM). The bioassay study also indicated that compound 3g displayed the best insecticidal activity against O. furnacalis and distinctive sublethal effect in regulating its growth and development. These 1,4-benzodioxane-tethered-rhodanine derivatives deserved further investigation as novel dual-chitinases inhibitor candidates in the control of O. furnacalis.