1. Introduction
Hyaluronic acid (HA) is a carbohydrate, more precisely a mucopolysaccharide, occurring naturally in most of the living organisms. It can be composed of numerous thousands of sugars long. While, not bound to other molecules, it binds to water giving it a firm viscous quality similar to “Jello”. The chemical structure of HA was essentially solved by Karl Meyer and his associates, who found that HA is a polyanion that consists of disaccharide repeats of D-glucuronic acid (GlcUA) and N-acetylglucosamine (GlcNAc) joined alternatively by β-1, 3 and β-1, 4 glycosidic bonds (Figure 1) (Balazs EA. and Gibbs 1970). Fig.(1): Disaccharide repeating unit ([D-glucuronic acid (1-β-3) N-acetyl-D-glucosamine (1-β-4)] n) of HA. (Balazs EA.…show more content… Generally, the size of the polymers ranges (molecular weight (푀푤) from 5,000 to 20 million Daltons (Da)). As, in vivo varies with the type of tissue. For example, HA in the human umbilical cord has a molecular mass of 3-4million Da, while, the molecular mass of HA from human synovial fluid is 6 million Da. However, the reported molecular weight of isolated HA polymers may be under evaluated depending on the extraction, isolation and analysis methods used. Consequently, HA molecular weight is not monodisperse and the experimentally determined polydispersity (푀푤/푀푛) of the polymer depends as well on both the method of extraction and the method of analysis used (Adam, N., and Ghosh, P., 2001). For example, the polydispersity values of a HA sample determined by high-performance liquid chromatography (HPLC) exhibited variations with the type of the column, the detection method, and the used flow rates (Porsch et al., 2008, Shiedlin et al., 2004). Accordingly, this resulted in a big variation of the values reported for the 푀푤 and polydispersity of HA between laboratories and showed the significance of methodology standardization for characterization and reporting of hyaluronan molecular properties (Boeriu GC et al.,…show more content… Time Event
1880 Portes reported that mucin from the vitreous body differs from other mucoids in cornea and cartilage then named it hyalomucine (Balazs EA, 1979) .
1934 Meyer and Palmer (1934) isolated and identified from the vitreous body a polysaccharide and named it "hyaluronic acid".
1930s–1950s Hyaluronan was isolated, identified, and characterized from different tissues of vertebrates. A few pathogenic bacteria were found to be hyaluronan producers using it to encapsulate their cells(Weissmann and Meyer 1954).
1940s–1970s The chemical structure of hyaluronan was demonstrated by Karl Meyer and his team. They used hyaluronidase to produce overlapping oligosaccharides that were structurally analyzed by conventional techniques (Weissmann and Meyer 1954). Interest emerged to use hyaluronan in eye surgery as a vitreous body substitute. Extraction processes from animal tissues were optimized to remove protein and to minimize hyaluronan degradation. First studies were initiated on hyaluronan production through bacterial fermentation and chemical