Antifungal Function Oriented Scaffold Hopping for the Discovery of Oxazolyl-oxazoline as a Novel Model against Fusarium graminearum

Discovery of novel structural models is extremely important in agrochemical innovation. Scaffold hopping was conducted, and 16 kinds of novel models were synthesized and biologically evaluated. Oxazolyl-oxazoline 25 showed a promising in vitro potential against Fusarium graminearum with EC50 value of 18.25 μM, which was 2.4 times more potent than that of carbendazim (EC50 = 43.06 μM). The antifungal structure–activity relationship (SAR) revealed that compound 25am had the most promising antifungal activity against F. graminearum, with an EC50 value of 13.46 μM, which was 3.2 more potent than that of carbendazim. Different from carbendazim, the candidate 25am could form five hydrogen bonds with the amino acid residues in β-tubulin in the molecular docking and could effectively inhibit the carbendazim-resistant F. graminearum strain. Scanning electron microscopy (SEM) revealed that compound 25am induced the mycelia of F. graminearum slight collapse. This work suggests that compound 25am should be prioritized for further evaluation for new antifungal agents.