Hyaluronic acid is one of the fundamental components of the connective tissue of humans. Gives the skin its particular properties of strength and shape retention. Its lack leads to a weakening of the skin by promoting the formation of wrinkles and blemishes. Its concentration in body tissues tends to decrease with age. In commerce, for cosmetic use, is sold under the name sodium hyaluronate because it is treated in order to adjust the pH.
In the amorphous matrix of a connective tissue hyaluronic acid (single glycosaminoglycan to be present in the matrix as such, ie not bound to a protein to form seed necessarily a proteoglycan) is responsible to maintain the degree of hydration, firmness, plasticity and viscosity, as it has in the space in a conformation aggregate pocketing so a considerable number of water molecules. It is also capable of acting as cementing substance and as a molecule anti-shock as well as an efficient lubricant (eg. in the synovial fluid) preventing damage to the tissue cells from physical stress.
The extreme length of the molecule together with its high degree of hydration allows multiple polymers of hyaluronic acid to organize themselves to form a lattice-like structure that has two main functions: create molecular scaffold to maintain the shape and the tone of the tissue; function as a filter against the free diffusion into the tissue of particular substances, bacterias, infectious agents.
Only the substances on the molecular weight low enough to go through the “mesh” of this network will be able to freely diffuse into the tissue; all substances from higher molecular weight as well as bacteria or viruses will remain entangled in the network. It should be noted that many bacteria are equipped with hyaluronidase, an enzyme that can break down hyaluronic acid, which allows them to break through.