CARRAGEENANS WITH COMPLEX SUBSTITUTION PATTERNS FROM RED ALGAE OF THEGENUS ERYTHROCLONIUM

Extracellular polysaccharides from three Erythroclonium spp. were show n, by a combination of compositional, linkage analyses, and Fourier tr ansform infrared and C-13-nuclear magnetic resonance spectroscopy, to be highly substituted carrageenans with at least five types of repeati ng disaccharide units. These are the carrabiose 2,4'-disulfate of iota -carrageenan, carrabiose 2-sulfate of alpha-carrageenan, the 6'-O-meth ylated counterparts of each of these repeating units, and 4',6'-O-(1-c arboxyethylidene)carrabiose 2-sulfate. The polysaccharides also contai n significant amounts of unsubstituted, 4-linked galactopyranose and s mall amounts of 4-linked 3-O-methylgalactopyranose and terminal glycos yl residues. The carrageenan preparations of the three species are sim ilar, differing only in the proportions of some components. (C) 1998 E lsevier Science Ltd.