Ten novel fenfuram-diarylamine hybrids were designed and synthesized. And their antifungal activities
against four phytopathogenic fungi have been evaluatedin vitro and most of the compounds demonstrated a significant antifungal activities against Rhizoctonia solani and Sclerotinia sclerotiorum.
Compound5eexhibited the most potent antifungal activity againstR. solaniwith an EC50 value of
0.037 mg/L, far superior to the commercially available fungicide boscalid (EC50= 1.71 mg/L) and lead
fungicide fenfuram (EC50= 6.18 mg/L). Furthermore, scanning electron microscopy images showed that
the mycelia on treated media grew abnormally with tenuous, wizened and overlapping colonies compared to the negative control. Molecular docking studies revealed that compound5efeatured a higher
affinity for succinate dehydrogenase (SDH) than fenfuram. Furthermore, it was shown that the 3-chlorophenyl group in compound5eformed a CH-pinteraction with B/Trp-206 and a Cl-pinteraction with
D/Tyr-128, rendering compound5emore active than fenfuram against SDH.