NEW NATURAL-PRODUCTS FROM MARINE-INVERTEBRATES

Extracts of marine invertebrates collected in British Columbia and Papua New Guinea have been screened for the presence of cytotoxic and enzyme modulatory metabolites. Chemical examination of several active extracts has resulted in the identification of a number of novel natural products. These include: contignasterol, 2, a steroid having a cis C/D ring junction; pseudaxinellin, 5, a cyclic heptapeptide; trididemnic acids A, 7, and B, 8, two aromatic alkaloids from a tunicate; the rubrolides A, 13, to H, 20, a family of highly halogenated tunicate metabolites; and motuporin, 22, a cyclic pentapeptide that is the first marine representative of the microcystin class of hepatotoxic and tumor-promoting cyclic peptides. Microcystin LR has been found in marine shellfish for the first time and it has been implicated as the cause of a severe liver disease that occurs in netpen reared salmon in British Columbia.