A wide diversity of sulfated polysaccharides are synthesized by different species of marine sponges.

Sulfated polysaccharides were extracted from four species of marine sponges by exhaustive papain digestion. These compounds were purified by anion-exchange and gel-filtration chromatography. Analysis of the purified polysaccharides revealed a species-specific variation in their chemical composition and also in their molecular masses. In the species Aplysina fulva we found a sulfated glucan with a glycogen-like structure. The other three species contained sulfated polysaccharides with variable proportions of galactose, fucose, arabinose and hexuronic acid and also with different degrees of sulfation. Although the complex nature of these polysaccharides did not allow complete structure determination, we detected the occurrence of 4-sulfated residues of fucose and arabinose in the species Dysidea fragilis. The biological role of these sulfated polysaccharides requires further investigation. They may be involved in the species-specific aggregation of sponge cells and/or in the structural integrity of sponge, resembling the proteoglycans of mammalian connective tissues.