Cytosporins A-D, novel benzophenone derivatives from the endophytic fungus Cytospora rhizophorae A761

Four novel benzophenone derivatives, cytosporins A-D (1-4), hemiterpene-conjugated phenolics with an unprecedented benzo [b][1,5] dioxocane skeleton, were isolated from Cytospora rhizophorae A761. The structures of the new compounds were fully characterized on the basis of extensive spectroscopic analysis. The deduced structure represents the first example of natural meroterpenoids which bear a benzo[b][1,5] dioxocane framework embodying hemiterpene and benzophenone moieties. Moreover, compounds 1-4 were evaluated for in vitro antimicrobial activity.