Exserolides A–F, new isocoumarin derivatives from the plant endophytic fungus Exserohilum sp.

Six new isocoumarin derivatives, exserolides A–F (1–6), were isolated from solid cultures of the plant endophytic fungus Exserohilum sp., together with four known metabolites (7–10). The structures of 1–6 were elucidated primarily by NMR experiments. The absolute configuration of the C-3 methine carbon in 1–5 was deduced via the circular dichroism data, whereas that of the 1,3-diol moiety in 6 was assigned from the 1H NMR data of its (R)- and (S)-MTPA diesters. Compounds 3 and 9 showed antifungal activity against the plant pathogen Fusarium oxysporum, whereas 6 displayed significant inhibitory effects against a small panel of bacteria.

Figure optionsDownload high-quality image (303 K)Download as PowerPoint slide