Polysaccharides of Algae XXXIII: Isolation and 13C-NMR Spectral Study of Some New Gel-forming Polysaccharides from Japan Sea Red Seaweeds

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Abstract
Fractional extraction of 8 red seaweed species [Hyalosiphonia caespitosa, Gloiosiphonia capillaris, Callophyllis rhynchocarpa, Gracilaria cuneifolia, Campylaephora hypnaeoides, Delesseria serrulata, Polysiphonia serrulata, Chondria decipiens] from the Japan Sea was carried out and the yields and monosaccharide composition of polysaccharide fractions were determined. Six species contained gel-forming polysaccharides which were characterized by chemical composition, gel strength measurements and by change of these parameters after alkali treatment. 13C-NMR spectroscopy was used for the structural analysis of gel-forming polysaccharides; a table of revised resonance assignments for agar- and porphyran-like polysaccharides is given. The chemical and spectral data indicated that the gel-forming polysaccharide from Campylaephora hypnaeoides is a porphyran analog and the polysaccharides from Gracilaria cuneifolia and Polysiphonia morrowii are modified agaroses having the sulfate and O-methyl groups mainly at position 6 of the 3-O-linked .beta.-D-galactopyranose residues.