MARINE BROWN-ALGAE OF FAMILY CYSTOSEIRACEAE - CHEMISTRY AND CHEMOTAXONOMY

The algal family Cystoseiraceae (order Fucales, class Phaeophyceae) includes the genera Acrocarpia, Acystis, Bifurcaria, Bifurcariopsis, Carpoglossum, Caulocystis, Coccophora, Cystophora, Cystoseria, Halidrys, Hormophysa, Landsburgia, Myriodesma, Scaberia and Stolonophora. Among these Cystoseira and Cystophora, the richest in species, are the most representative of the family. Cystoseira is a genus of worldwide distribution with about 80% of the species occurring along the Mediterranean and adjoining Atlantic coasts, while Cystophora is limited to the coasts of Australia and New Zealand. Members of the genus Cystoseira generally synthesise tetraprenyltoluquinols. Compounds of the same structural type have also been isolated from species belonging to the genera Halidrys (northern coasts of England), Bifurcaria (coasts of the Galapagos Islands), and Cystophora. Some species of these last two also elaborate linear diterpenoids as do some Cystoseira species. Tetraprenyltoluquinols have never been found in Caulocystis and Acrocarpia, which instead accumulate acetogenins. Finally, Landsburgia is the sole genus which produces naphthoquinone derivatives. Phytochemical studies of the secondary metabolites of the remaining genera are not reported. The chemistry of secondary metabolites and their distribution in the family Cystoseiraceae will be illustrated, and some taxonomic implications will be discussed.