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 calcareou s red alga Corallina pilulifera was studied by methylation analysis be fore 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 cons ist 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 ra tio of 29:20:5:2:1:20:23. Its agaran-like backbone built up of alterna ting 3-linked beta-D-galactopyranose and 3-linked alpha-L-galactopyran ose residues bears single beta-D-xylopyranosyl substituents at positio n 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.