Structure and Anticoagulant Activity of a Galactofuranose-Containing Sulfated Polysaccharide from the Green Seaweed, .

A water-soluble sulfated polysaccharide, F2-1, was obtained from the marine green alga, , using ion-exchange and size-exclusion chromatography. Structure analysis showed that the F2-1 was a sulfated arabinan comprising Ara, Rha, Man, Gal, and Xyl with an 18% sulfate content and a molecular weight of 100 kDa. Methylation analysis combined with desulfation, GC-MS, IR, and NMR spectroscopy showed that the backbone of F2-1 was →4)-β-L-Ara(1→ residue. Its 2- and/or 3- positions showed sulfate modification; additionally, the 2- or 3- position showed branch points. The side chains were composed of →5)-β-D-Gal, (1→2,6)-β-D-Gal(1→, (1→2)-β-L-Rha4S, →4)-α-D-Glc(1→, and terminal α-D-Gal(1→ and β-D-Xyl(1→. Polysaccharides containing β-D-galactofuranose are rarely found in seaweed. F2-1 exhibited significant anticoagulant activity in vitro. Our findings suggested that the green-tide alga, , can be considered as a useful resource for bioactive polysaccharides.