Camphoryl thiosemicarbazide derivatives: promising multitarget fungicide candidates against Colletotrichum fructicola

BACKGROUND Pear anthracnose, caused by Colletotrichum fructicola , is a highly destructive disease that inflicts substantial economic losses worldwide. However, current antifungal agents mainly target known target proteins, and long‐term use leads to increased resistance of C. fructicola . Thus, developing multitargeted antifungal agents based on new targets is an effective way to solve the problem of drug resistance. RESULTS Twenty camphor derivatives containing thiosemicarbazide groups were synthesized and evaluated for antifungal activity against C. fructicola . Among them, compound 1a [median effective concentration ( EC 50 ) = 3.76 mg L −1 ] exhibited the strongest antifungal activity, superior to kresoxim‐methyl ( EC 50 = 9.69 mg L −1 ). The in vivo antifungal test demonstrated that 1a had better protective and curative effects against pear anthracnose than kresoxim‐methyl. The toxicity results showed that 1a exhibited low toxicity to LO2 and HEK293 cell lines. Mechanistically, 1a can destroy hyphae morphology and cell ultrastructure, increase cell membrane permeability, affect the normal expression pathway of soluble proteins and destroy the normal metabolic function of phospholipase C. Additionally, the laccase inhibitory activity results showed that 1a [Median inhibitory concentration ( IC 50 ) = 7.14 mg L −1 ) had stronger laccase inhibitory activity than cysteine ( IC 50 = 23.99 mg L −1 ). Furthermore, molecular docking studies showed that 1a interacted with laccase by forming hydrogen bonds with amino acid residues ASP444 and ARG442 . CONCLUSION This study showed that compound 1a can serve as a promising multitarget fungicide candidate for controlling C. fructicola , with its targets at least including the cell membrane and laccase of the C. fructicola .