Synthesis, Biological Activity, and Toxicity to Zebrafish Embryo of Benzamides Substituted with 1,2,4-Oxadiazole-Linked Pyrazole

Abstract

To explore novel pesticidal lead compounds with potential activity, a series of new benzamide compounds substituted with 1,2,4-oxadiazole-linked pyrazole were designed and synthesized based on the active substructure splice principle. The preliminary bioassay revealed that most compounds exhibited good larvicidal activities against Mythimna separate, Helicoverpa armigera, Ostrinia nubilalis, and Spodoptera frugiperda. Additionally, all synthesized compounds displayed potent antifungal activities against Pyricularia oryzae, and 13h was the most active compound with an inhibitory rate of 88.9% at the concentration of 50 mg/L. The acute toxicity assay found that 13h was toxic to zebrafish embryos with an LC50 value of 2.43 mg/L. Thus, the strong insecticidal and antifungal properties of 13h, together with its moderate toxicity, make it a promising candidate for a new pesticide lead.