Mucilaginous substances from macroalgae: an overview.

Macroalgae (seaweeds) produce a diversity of mucilaginous substances, some of which are of considerable commercial and biotechnological importance (e.g. alginate, carrageenan, agar). They are involved in vivo in conferring structural integrity as cell wall materials (alginate, agar, carrageenan), the prevention of desiccation (sulphated fucans), selective absorption of ions (alginate, sulphated fucans) and in bioadhesion (various glycoproteins and mucopolysaccharides). The current state of knowledge with respect to the structure, localization, biosynthesis and secretion of some of the more important of these substances is summarised.