Design, synthesis, and antifungal activity of nicotinamide derivatives containing diphenylamine moieties

In order to find amide compounds with desired antifungal activity, 16 nicotinamide derivatives containing diphenylamine moieties were prepared by condensation of 2-chloronicotinic acid with substituted N¹-phenylbenzene-1,2-diamines based on the structure of fungicide boscalid. The structures of the synthesized compounds were characterized by ¹H NMR, ¹³C NMR, ESI-MS, and elemental analysis. Among the compounds screened, compound 3a had high inhibitory effects against Rhizoctonia solani in vitro and in vivo, which slightly exceeded boscalid. The study of the structure-activity relationship provides important information for further structural optimization. Molecular docking offered a reasonable explanation to guarantee its fungicidal activity against R. solani. These results could provide a benchmark for understanding the antifungal activity against the phytopathogenic fungus R. solani and prompt us to develop more potent fungicides.

Graphical abstract

Sixteen nicotinamide derivatives containing diphenylamine moieties were prepared based on the structure of fungicide boscalid. Thereinto, compound 3a showed high antifungal activity against Rhizoctonia solani. Structure-activity relationship study provided important information for further structural optimization. Molecular docking offered a reasonable explanation to guarantee its fungicidal activity.