Inhibition of Free Radical Degradation in Medical Grade Hyaluronic Acid - Hyaluronic Acid for Biomedical and Pharmaceutical Applications - page 106

Therefore, microbial hyaluronan production using either pathogenic
streptococci or safe recombinant hosts, containing the necessary
hyaluronan synthase, is nowadays more and more preferred [6].

The majority of the HA producing technologies has focused mainly
on obtaining a highly pure polymer suitable for clinical applications
[19]. Several separation techniques such as protease digestion, HA
ion-pair precipitation, membrane ultrafiltration, HA non-solvent
precipitation and lyophilisation [20, 21] have been used to obtain the
pure compound. However, an economically appropriate and simple
method is still needed for the production of high grade and pure HA
for medical applications.

One drawback of the extraction process is an inevitable degradation
of hyaluronan, caused by: (a) the endogenous hyaluronidase activity in
animal tissues, breaking down the polymer chain through enzymatic
hydrolysis; and (b) the harsh conditions of extraction. Extraction
protocols have been improved over the years, but still suffer from
the uncontrolled free radical degradation during the HA isolation
procedures [6]. To improve the quality and to minimise the risk of
hyaluronan degradation during its production, several modifications
were performed on the purification and isolation steps [22-25].

In the current work we investigate glutathione (GSH) ( Figure 5.2 )
as an efficient free radical scavenger/antioxidant for inhibiting the
oxidative degradation of hyaluronan. We have also investigated
the effect of pH conditions on protective activity of GSH against
hyaluronan free radical degradation.

SH

O O H O

N

NH

HO OH

NH 2 O

Figure 5.2 Chemical structure of GSH