Hot water-soluble polysaccharides from tetrasporic Pterocladia capillacea

Tetrasporic Pterocladia capillacea was sequentially extracted with water at room temperature, 50 degrees, 70 degrees and 90 degrees. The polysaccharides obtained by extraction at 90 degrees were fractionated by ion-exchange chromatography on DEAE Sephadex A-50 (Cl-), eluting with water and solutions of increasing sodium chloride concentration; seven fractions were separated. The two major fractions, one eluted with water and the other with 0.1 M NaCl, comprised 66.9% of that recovered and were mainly agarose. Structural analysis of the fraction eluted with 0.7 M NaCl is consistent with a backbone formed mainly by alternating 3-linked beta-D-galactose and 4-linked alpha-L-galactose residues, highly substituted with sulphate and having single stubs of xylose and galactose.