Structural studies on fucoidans from the brown seaweed Sargassum stenophyllum

The brown seaweed Sargassum stenophyllum biosynthesizes two different sets of fucoidans. One of them is characterized by higher percentages of glucuro nic acid and fewer sulfate groups, which are situated on different sugar un its. alpha -L-Fucose was the major component but other sugars like beta -D- galactose, beta -D-mannose, alpha -D-glucuronic acid, alpha -D-glucose and beta -D-xylose were also in substantial amounts. Fucoidans from the other s et contain small amounts of alpha -D-glucuronic acid and high percentages o f sulfate groups, which are concentrated on the fucose residues, with only fucose and galactose as major components. Structural studies of one fucoida n from each set suggest that these products have a general basic structure that has a formal resemblance to that of the fucosylated chondroitin sulfat es from the body wall of sea cucumbers, namely, a linear core (formed mainl y by (1 -->6)-beta -D-galactose and/or (1 -->2)-beta -D-mannose units) with branched chains of 'fucans' (formed by (1 -->3) and/or (1 -->4)-alpha -L-f ucose, (1 -->4)-alpha -D-glucuronic acid, terminal beta -D-xylose and, some times, (1 -->2)-alpha -D-glucose). In fucoidans from the second set, the 'c ore' is reduced to short galactan chains. (C) 2001 Elsevier Science Ltd. Al l rights reserved.