Nematicidal resorcylides from the aquatic fungus Caryospora callicarpa YMF1.01026.

This study investigated metabolites with activities against plant parasite nematodes from the fresh-water fungus Caryospora callicarpa YMF1.01026. We obtained three novel tetradecalactone metabolites, caryospomycins A-C, with such activities. The chemical structures of these were determined through NMR spectroscopic analysis and were found to belong to the 14-membered macrolides with a fused 1,2-dimethoxy-4-hydroxybenzene ring, a rare structure among the resorcylides. In the in vitro tests, all three compounds exhibited moderate killing activity against the nematode Bursaphelenchus xylophilus. To our knowledge, this is the first report of secondary metabolites in the aquatic fungal genus Caryospora.