Labdane and Tetranorlabdane Diterpenoids from Botryosphaeria sp MHF, an Endophytic fungus of Maytenus hookeri

Five new diterpenoids, named botryosphaerins A-E (1-5, resp.), including one labdane and four tetranorlabdane diterpenes, were isolated from the solid culture of the endophytic fungal strain Botryosphaeria sp. MHF of Maytenus hookeri, together with seven known diterpenoids, namely 13,14,15,16-tetranorlabd-7-ene-19,6 beta: 12,17-diolide (6), acrostalidic acid (7), acrostalic acid (8), agathic acid (9). isocupressic acid (10), LL-Z1271 beta (11), and CJ-14445 (12). The structures of all compounds were established on the basis of comprehensive spectroscopic studies. The relative configurations of 1 and 2 were determined by single-crystal X-ray diffraction analyses. All compounds except 4 were evaluated for their inhibitory activities against several pathogenic bacterial and fungal strains. However, only compound 12 showed significant inhibitions against Candida albicans, Saccharomyces cerevisiae, and Penicillium avellaneum UC-4376 with nystatin as a positive control.