Two new isopimarane diterpenoids from the endophytic fungus Xylaria sp. SNB-GTC2501

Two new isopimarane diterpenoids, xylabisboein A (1) and B (2), as well as three known secondary metabolites (i.e., (−)-5-methylmellein (3), mellein-5-carboxylic acid (4) and ergosterol peroxide (5)), were isolated from a solid culture of the endophytic fungus Xylaria sp. SNB-GTC2501. The structures were elucidated by spectroscopic analysis and the absolute configuration of xylabisboein A (1) was determined by X-ray crystallographic analysis. All of the compounds were tested for their antimicrobial and cytotoxic activities