Design, synthesis, insecticidal activities, and molecular docking of novel pyridylpyrazolo carboxylate derivatives

Based on our previous work, using the strategies of "scaffold hopping" and "intermediate derivatization method" (IDM), a total of 44 novel pyridylpyrazolo carboxylate derivatives were designed and synthesized. The structures of these compounds were identified by H-1 NMR and C-13 NMR, and the insecticidal activities of the target compounds against Plutella xylostella and Spodoptera frugiperda were tested. Compound G35 showed the best insecticidal activities against P. xylostella (LC50 = 33.65 mg/L) and S. frugiperda (mortality rate = 61.21% at 100 mg/L). Preliminary structure-activity relationship analysis showed that the introduction of amino group and acetamide on the benzene ring helped to improve the insecticidal activity of the scaffold. Molecular docking model between compounds G34 or G35 and Ryanodine receptors (RyRs) of P. xylostella showed that RyRs may be a potential target of this series compounds and explained the difference in insecticidal activities. These findings provided guidance for further optimization of the pyridylpyrazolo carboxylate scaffold as potential insecticide.