ALGAL CAROTENOIDS .54. CAROTENOIDS OF BROWN-ALGAE (PHAEOPHYCEAE)

The qualitative and quantitative carotenoid composition is reported fo r the brown algae Fucus serratus, F. vesiculosus, Ascophyllum nodosum, Pelvetia canaliculata, Laminaria digitata and L. saccharina. Emphasis was made on the identification of all minor carotenoids, on the demon stration of naturally occurring geometrical isomers and on the recogni tion of isolated artifacts. All-trans fucoxanthin was the major carote noid (primary xanthophyll) and beta,beta-carotene the only carotene pr esent in all six species. The diepoxidic all-trans violaxanthin was th e second major xanthophyll. No acetylenic carotenoids were encountered amongst the minor carotenoids. These included cryptoxanthin-like, cry ptoxanthin-5,6-epoxide-like, antheraxanthin-like, latoxanthin-like and mactraxanthin-like carotenoids on the 0.01-1.5% of total carotenoid l evel, and the previously encountered zeaxanthin, neoxanthin (all-trans ) and fucoxanthinol on the 0.01-0.02% of total carotenoid level. Viola xanthin and neoxanthin were partly isolated as the furanoid rearrangem ent products. Cis-isomers in general were isolation artifacts. The che mosystematic implications are discussed. A biosynthetic scheme based o n the carotenoids encountered is considered.