Polyoxygenated steroids from the gorgonian Isis hippuris.

Eleven new hippuristanols (1-4, 7-9, and 11-14), along with eight known metabolites (5, 6, 10, and 15-19), have been isolated from the gorgonian coral Isis hippuris. Single-crystal X-ray diffraction analyses supported the structure elucidation of known steroids 5 and 10. The absolute structures of hippuristanols were established by application of modified Mosher's method on 19. Compounds 14-19 have been found to exhibit significant cytotoxicity against several cancer cell lines.