INTRODUCTION
Hyaluronic acid (HA) is one of the fundamental components of the connective tissues in humans and other mammals. It gives the skin its properties of resistance and its abilities to maintain its shape. In fact a deficiency of HA causes a weakening of the skin with the formation of wrinkles and blemishes. Its concentration in the tissues tends to decrease with age due to the presence of particular enzymes, hyaluronidases, which catalyse HA chain degradation.
Chemically the HA is a linear polymer belonging to the class of glycosaminoglycans. The polysaccharide chain is made of thousands of disaccharides, themselves composed of glucuronic acid (a glucose derivative) and N-acetylglucosamine, linked together via alternating β-1,4 and β-1,3 glycosidic bonds (Figure 1).
The HA chains consist of 2,000-25,000 disaccharides that correspond to a molecular mass of 106-107 Da and a length of 2-25 μm.
In vivo all the carboxylic groups of the HA are ionized, giving to the molecule a high polarity and consequently the capacity to complex many water molecules. Therefore the task of the HA in the amorphous matrix of the connective ...
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