Figure 1.

Structure of the sulfated fucose-rich polysaccharides from brown algae and echinoderms. (a) Fucoidans from brown algae are composed of α (1→3)-linked fucose units or alternating α (1→3)- and α (1→4)-linked fucose units. Mannose, galactose, xylose, uronic acid and branches of other monosaccharides make this polysaccharide highly variable and with complex structures. (b) SFs from echinoderms are made up of a repetitive tetrasaccharide units, formed by α (1→3) units and with a regular sulfation pattern at positions 2 and 4. (c) Structure of a fucCS from sea cucumbers. This polysaccharide has a chondroitin sulfate-like backbone, with branches of α-fucose linked to position 3 of the β-glucuronic acid of the central core. These fucose branches varies among species. In the specie L. grisea, for example, three types of branches are observed: α-Fuc-2,4diSO₄, α-Fuc-3,4diSO₄ and disaccharides composed of α-Fuc1→2-α-Fuc-3SO₄→. The sulfated fucose-rich polysaccharides from echinoderms have a more regular and repetitive structures compared with brown algae polysaccharides.