Hydnocarpic acid and chaulmoogric acid, the principal antifungal compounds in Hydnocarpus hainanensis seed extract, inhibit fatty acid β-oxidation and suppress infection of Magnaporthe oryzae.

BACKGROUND

Environmentally sustainable management of plant fungal diseases requires green agrochemicals that combine high efficacy with novel modes-of-action. Rice blast caused by Magnaporthe oryzae is a destructive crop fungal disease, and developing botanical fungicides with new antifungal mechanisms is urgently needed for its green control.

RESULTS

In this study, we report that an ethanol-petroleum ether crude extract of Hydnocarpus hainanensis seeds (designated DF2) strongly suppresses infection of the rice blast fungus M. oryzae. Bioactivity-guided fractionation of DF2 identified hydnocarpic acid and chaulmoogric acid as the principal antifungal constituents, which inhibit conidial germination, appressorium formation and plant infection by M. oryzae. Furthermore, treatment with DF2 significantly perturbed carnitine-related metabolites and severely attenuated fatty acid β-oxidation in M. oryzae conidia. Interestingly, exogenous addition of methylenecyclopropyl acetic acid to the M. oryzae conidial inoculum mimicked these effects, whereas supplementation with l-carnitine reversed them.

CONCLUSION

Taken together, our findings indicate that hydnocarpic acid and chaulmoogric acid disrupt fatty acid β-oxidation and impede infection of M. oryzae, and suggest that DF2 could serve as a potential botanical fungicide to control fungal diseases of crops. © 2026 Society of Chemical Industry.