Two New Solanapyrone Analogues from the Endophytic Fungus Nigrospora sp. YB‐141 of Azadirachta indica

Two new solanapyrone analogues, solanapyrones N and O (1 and 2, resp.), and three known compounds, solanapyrone C (3), nigrosporalactone (4), and phomalactone (5), were isolated from the fermentation culture of Nigrospora sp. YB-141, an endophytic fungus isolated from Azadirachta indica A. Juss. The structures of the new compounds were elucidated on the basis of spectroscopic analysis. The antifungal activities of 1-5 towards seven phytopathogenic fungi were tested. Most of the compounds exhibited no or only weak antifungal activities.