Caripyrin, a new inhibitor of infection-related morphogenesis in the rice blast fungus Magnaporthe oryzae

Caripyrin (trans-5-(3-methyloxiranyl)pyridincarboxylic acid methyl ester, 1), a new pyridyloxirane, was isolated from submerged cultures of the basidiomycete Caripia montagnei. The compound was found to inhibit conidial germination and appressorium formation in the rice blast fungus Magnaporthe oryzae, whereas the infection-related morphogenesis in several other phytopathogenic fungi was not affected. In plant assays on rice, 1 was found to protect plants more efficiently against fungal infection than the structurally related fungal secondary metabolite, fusaric acid. Contrary to the latter, 1 was neither cytotoxic, antibacterial, nor nematicidal. The Journal of Antibiotics (2010) 63, 285-289; doi:10.1038/ja.2010.31; published online 9 April 2010