Synthesis and antiherpetic activity of carboxymethylated and sulfated hyaluronan derivatives

Native high molecular weight hyaluronan (HMW-HA, MW = 1 × 106 g/mol) and a thermally degraded low molecular weight hyaluronan (LMW-HA, MW = 1.3–1.4 × 105 g/mol) were carboxymethylated providing products with degrees of carboxymethylation (DSCM) of up to 0.8. Sulfation of resulting carboxymethyl hyaluronan (CM-HA) and hyaluronan (HA) was performed by different sulfation procedures enabling the control of the degree of sulfation (DSS) in the obtained new carboxymethyl hyaluronan sulfates (CM-HA-S) and hyaluronan sulfates (HA-S), respectively, in a range between 0.9 and 3.3. Both carboxymethylation and sulfation were found to take place preferentially at the primary hydroxyl groups of HA. The antiviral activity of these synthesized HA derivatives was tested against Herpes simplex virus type 1. Both HA-S and CM-HA-S derivatives with high DSS values of about 3.0 exhibit a strong antiherpetic activity. The CM-HA derivatives were found to be not active and an additional effect of introduced carboxymethyl groups on the antiherpetic activity of CM-HA-S derivatives was not observed. In the case of HA-S, the antiviral efficacy can be correlated with the DSS and becomes stronger with increasing DSS values.