Occurrence of Carrageenan Structure in an Agar from the Red Seaweed Digenea simplex (Wulfen) C. Agardh (Rhodomelaceae, Ceramiales) with a Short Review of Carrageenan-Agarocolloid Hybrid in the Florideophycidae

R. Takano, K. Shiomoto, K. Kamei, S. Hara,  and S. Hirase


A fractionation study of crude agar from the red seaweed Digenea simplex led to isolation of a galactan sulfate fraction consisting of a carrageenan-agaroid hybrid-type backbone. This polysaccharide fraction, containing D-galactose (Gal), L-Gal, 3,6-anhydro-D-galactose (D-AnGal), L-AnGal, sulfate and a small amount of xylose, appeared to consist of repeating units of both 4-O-β-D-galactopyranosyl-3,6-anhydro-L-galactose (agarobiose) and 4-O-β-D-galactopyranosyl-3,6-anhydro-D-galactose (carrabiose) on the basis of results from a partial methanolysis study. Two other repeating disaccharide units in the backbone, 4-O-β-D-galactopyranosyl- L-galactose and 4-O-β-D-galactopyranosyl-D-galactose, were also suggested by the methylation study. The sulfate groups were also suggested to be located at O-4 of (1→3)-linked D-Gal, O-6 of (1→3)-linked D-Gal, O-6 of (1→4)-linked L-Gal and/or O-2 of (1→4)-linked AnGal residues, besides O-3 of (1→4)-linked D-Gal residue. Co-occurrence of carrageenan and agarocolloid backbone structure among the genera in the Florideophycidae was also reviewed.

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Botanica Marina publishes high-quality contributions from all of the disciplines of marine botany at all levels of biological organisation from subcellular to ecosystem: chemistry and applications, genomics, physiology and ecology, phylogeny and biogeography. Research involving global or interdisciplinary interest is especially welcome as well as applied science papers dealing with emerging conceptual issues or developing technologies.