Fig. 1. Hyaluronic acid monomer unit.

Hyaluronic acid is a polysaccharide that consists of D-glucuronic (left) acid and D-N-acetylglucosamine (right) disaccharide units. They are bound together by a β-1,3 glycosidic bond. Additionally, two disaccharide units are linked by a β-1,4 glycosidic bond.