Fig 1: Structure of HA

Hyaluronic acid (Hyaluronan) belongs to the group of glycosaminoglycans (GAGs), but unlike other GAGs like Heparan sulfate, Chondroitin sulfate or Keratan sulfate, it cannot be found as a proteoglycan. It represents a non-sulfated polysaccharide consisting of alternating residues of D-glucuronic acid and N-acetylglucosamine (Fig 1). In the human umbilical cord and synovial fluid, the size of HA is reported to be about 3,000,000 Da (a flexible chain of 4000 disaccharide units).

HA is one of the major components of the extracellular matrix and it absorbs high amounts of water thus giving tissues the ability to resist compression. Furthermore, Hyaluronan contributes significantly to cell proliferation and cell migration. As HA levels often correlate with malignancy and poor prognosis of certain cancers, it can be used as a tumor marker. As Hyaluronan plays a role in skin healing, it’s a widely used ingredient of skin-care products.