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 1 (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 I was determined by comparison of optical rotation and CD experiments with those of 2 and 3.