Harziane and cadinane terpenoids from the alga-endophytic fungus Trichoderma asperellum A-YMD-9-2

In addition to the known harziandione (1), one new diterpenoid, 3S-hydroxyharzianone (2), and two new sesquiterpenoids, 4-cadinen-11,12-diol (3) and 4-cadinen-11,13-diol (4), were isolated from the culture of Trichoderma asperellum A-YMD-9-2, an endophytic fungal strain from the marine red alga Gracilaria verrucosa. The structures and relative configurations of new isolates were established by analysis of spectroscopic techniques, including 1D/2D NMR, IR, and MS, and their absolute configurations, except for those at C-11 of 3 and 4, were assigned by comparison of the ECD curve or specific optical rotation data with those of analogues. Compound 2 may be an intermediate in the biosynthesis of harziandione from harzianone, while 3 and 4 represent the second occurrence of cadinane sesquiterpenoids in Trichoderma. Compounds 2 - 4 exhibited potent inhibition of several marine phytoplankton species.