Fractionation and analysis of fucans from brown algae

Abstract

Cell walls were isolated from the brown algae Pelvetia canaliculata, Fucus vesiculosus, Sargassum muticum (Fucales) and Laminaria digitata (Laminariales) and then submitted to sequential chemical extraction. Various fucans were isolated, i.e. free fucans released upon cell wall isolation, and fucans extracted with Triton X-100, acid and alkali. The fucans were present in a continuous spectrum of compounds, from high-uronic-, low-sulphate- and fucose-containing polymers to highly sulphated homofucans. Their composition was, however, related to their position of isolation in sequential extraction procedure. The free fucans were similar in composition to homofucans in P. canaliculata, F. vesiculosus and L. digitata and to glucuronofucogalactans in S. muticum; the fucans released by Triton and those extracted by acid from the isolated cell walls were xylofucoglucuronan-like; and the fucans released upon alginate extraction were again very similar in composition to typical fucoidans. The possible distribution of the various fucans throughout the cell wall is discussed.