Synthesis and biological evaluation of novel pyrazole carboxamide with diarylamine-modified scaffold as potent antifungal agents

Twenty-seven novel pyrazole carboxamides with diarylamine-modified scaffold were designed, synthesized and characterized in detail via ¹H NMR, ¹³C NMR, IR and ESI-HRMS. Preliminary bioassays showed that some of the target compounds exhibited good antifungal activity against Rhizoctonia solani, Rhizoctonia cerealis and Sclerotinia sclerotiorum. Among them, compound 9c-7 exhibited the highest antifungal activities against R. solani, R. cerealis and S. sclerotiorum in vitro with IC₅₀ values of 0.013, 1.608 and 1.874 μg/mL, respectively. Notably, compound 9c-7 still presented the highest fungicidal activities against R. solani in vivo with an IC₅₀ value of 22.21 μg/mL. Molecular docking simulation results reveal that compound 9c-7 binds well to the hydrophobic pockets of the receptor protein succinate dehydrogenase. This study suggests that compound 9c-7 could act as a potential fungicide to be used for further optimization.