LAUSR

Our recent investigation on the insecticidal activities of several doramectin derivatives preliminarily revealed that the presence of hydrogen bonds at the C4″ position of the molecule with target protein GABA receptor was crucial for retaining high insecticidal activity. As a continuation of our research work on the development of new insecticides, two series of novel acylurea and acylthiourea doramectin derivatives were designed and synthesized. The bioassay results indicated that the newly synthesized compounds (5o, 5t, and 6t) exhibited higher insecticidal activity against diamondback moth, oriental armyworm, and corn borer than the controls compounds doramectin, commercial avermectins, chlorbenzuron, and the lead compound 3g in our laboratory. Specifically, compound 5t was identified as the most promising insecticide against diamondback moth with a final mortality rate of 80.00% at the low concentration of 12.50 mg/L, showing approximately 7.75-fold higher potency than the parent doramectin (LC50 value of 48.1547 mg/L), 6.52-fold higher potency than commercial avermectins (LC50 value of 40.5507 mg/L), and 3.98-fold higher potency than 3g (LC50 value of 24.7742 mg/L). Additionally, molecular docking simulations revealed that 5t (2.17, 2.20, 2.56, and 2.83 Å) displayed stronger hydrogen bond action in binding with GABA receptor, better than that of 5o (1.64 and 2.15 Å) and 6t (2.20 and 2.31 Å) at the C4″ position. This work demonstrated that these compounds containing hydrogen bond groups might contribute to the improvement of insecticidal activity and supplies certain hints toward structure optimization design for the development of new insecticides. KEYWORDS: Acylurea, acylthiourea, insecticidal activities, molecular docking, oriental armyworm, diamondback moth, and corn borer.