Structure of a sulfated xylogalactan from the calcareous red alga Corallina pilulifera P. et R. (Rhodophyta, Corallinaceae)

The structure of a sulfated polysaccharide isolated from the calcareous red alga Corallina pilulifera was studied by methylation analysis before and after desulfation or Smith degradation, as well as by ID and 2D H-1 and C-13 NMR spectroscopy. The polysaccharide was shown to consist of D-galactose, L-galactose, 2-O-methyl-L-galactose, 3-O-methyl-L-galactose, 6-O-methyl-D-galactose, D-xylose, and sulfate in a molar ratio of 29:20:5:2:1:20:23. Its agaran-like backbone built up of alternating 3-linked beta-D-galactopyranose and 3-linked alpha-L-galactopyranose residues bears single beta-D-xylopyranosyl substituents at position 6 of beta-D-galactose residues, whereas sulfate and O-methyl groups occupy positions 2 and 3 of alpha-L-galactose and position 6 of beta-D-galactose residues. (C) 1997 Elsevier Science Ltd.