Water-soluble polysaccharides of the red alga Laurencia pinnatifida. Part I. Constituent units

Water-soluble polysaccharides extracted from the alga Laurencia pinnatifida consist of a glucan and a galactan sulphate. The latter contains residues of D- and L-galactose, 6-O-methyl-D-galactose, 2-O-methyl-L-galactose, 3,6-anhydro-L-galactose, 3,6-anhydro-2-O-methyl-L-galactose, and sulphate. Other constituents are D-galacturonic acid and D-xylose but it is not yet known whether these are constituents of the galactan or of associated polysaccharides. Sulphate groups occur on C-6 of both L-galactose and 2-O-methyl-L-galactose, and on C-2 of D-galactose units.