Guaiane sesquiterpenes and isopimarane diterpenes from an endophytic fungus Xylaria sp.

Nine oxygenated guaiane-type sesquiterpenes and three isopimarane diterpenes were isolated from the culture broth of an endophytic fungus, Xylaria sp. YM 311647, obtained from Azadirachta indica. The structures of these compounds were elucidated by interpretation of spectroscopic data. The absolute configurations of two of these were confirmed by X-ray crystallographic analysis. All of the compounds were tested for their antifungal activities against five pathogenic fungal cells. The results showed that nine sesquiterpenes were moderately active against Candida albicans and Hormodendrum compactum with MIC values ranging from 32 to 256μg/ml, while the diterpenes were more active; One of these exhibited the most potent inhibitory activity against C. albicans and Pyricularia oryzae with MIC values of 16μg/ml.