Circumdatin I, a New Ultraviolet-A Protecting Benzodiazepine Alkaloid from a Marine Isolate of the Fungus Exophiala

A new ultraviolet-A (UV-A) protecting benzodiazepine alkaloid, circumdatin I ( 1 ), along with the previously described circumdatin C ( 2 ) and circumdatin G ( 3 ), have been isolated from the mycelium of a marine-derived fungus of the genus Exophiala . The structures of the three circumdatins were assigned on the basis of physicochemical evidence. The absolute stereochemistry of 1 was determined by comparison of optical rotation and CD experiments with those of 2 and 3 .