Cytorhizins A–D, Four Highly Structure-Combined Benzophenones from the Endophytic Fungus Cytospora rhizophorae

Cytorhizins A-D, four novel polyketide heterodimers, were isolated from the endophytic fungus Cytospora rhizophorae A761. These new compounds shared an unprecedented 6/6/5/6/8 or 6/6/5/6/7 pentacyclic ring system and fused as a fascinating cagelike skeleton, embodying by a polyoxygenated isopentyl unit and a highly structure-combined benzophenone scaffold. Their structures were elucidated by extensive spectroscopic analyses and X-ray diffraction techniques. Moreover, compounds 1-4 were evaluated for in vitro cytotoxicity and antimicrobial activity.