Antifungal activity and the mechanism of dehydrocostus lactone from Saussurea costus roots.

BACKGROUND

Rice blast, which is caused by the fungal pathogen Magnaporthe oryzae, is one of the most devastating diseases on rice worldwide. The effectiveness of chemical fungicides is being increasingly challenged by pathogen resistance and environmental pollution, underscoring the urgent need for eco-friendly biocontrol alternatives. Herein, we report the antifungal potential of bioactive components in Saussurea costus against M. oryzae infection and explore the underlying mechanism.

RESULTS

Essential oil (EO) from Saussurea costus roots was screened from the plant EOs library, and exhibited excellent preventive effects against M. oryzae at a concentration of 100 μg mL-1. Bio-guided isolation of Saussurea costus EO identified dehydrocostus lactone (DHLC) as the active ingredient. The chemical structure of DHLC was determined through spectroscopic analyses. DHLC displayed potent antifungal activity, with half-maximal effective concentration (EC50) values of 17.76 μg mL-1 and 9.88 μg mL-1 against conidial germination and appressorium formation, respectively. DHLC disrupted cell wall integrity and membrane permeability and inhibited autophagy in M. oryzae. DHLC also demonstrated broad-spectrum protective effects against several other species of phytopathogenic fungi.

CONCLUSION

The results of our study demonstrate that DHLC isolated from Saussurea costus roots prevents rice blast disease by inhibiting the infection-related morphogenesis of M. oryzae, highlighting its potential as an alternative bioagent to control fungal diseases in plants. © 2026 Society of Chemical Industry.