* Fucoidan, a complex sulfated polysaccharide containing substantial percentages of L-fucose and sulfate ester groups, is a constituent of brown algae and some marine invertebrates.

* Besides L-fucose, it frequently contains D-xylose, D-galactose, D-mannose and D-glucuronic acid.

* Fucoidan has no determined molecular formula, and its structure built up mainly of (1→2)-linked, 4-O-sulfated fucopyranose. Residues has been generally accepted for fucoidan from L.Aminaria Japonical / Undaria pinnatifida.