Alginate
Alginates are produced by brown seaweeds (Phaeophyceae, mainly Laminaria). Alginates or algin, is a generic term for the salts and derivatives of alginic acid. Alginate is a copolymer of 1 → 4 linked β-D-mannuronic acid (M) and α-L-guluronic acid (G). Figure presents the structure of alginate. This acid polysaccharide or gum occurs as the insoluble mixed calcium, sodium, potassium and magnesium salt in the Phaeophyceae brown seaweeds.