Inhibitory effects of different antioxidants on hyaluronan depolymerization

Hyaluronan (HA) was depolymerized by hydroxyl radicals generated from hydrogen peroxide and cupric ions. Inhibition of HA degradation by four well-known antioxidants was investigated, as HA can scavenge reactive oxygen species (ROS). Change in hyaluronan molecular weight was observed by size-exclusion chromatography. Inhibition of HA degradation was estimated from the retention times observed. It was found that HA degradation was inhibited in a clearly concentration-dependent manner by mannitol, thiourea and vinpocetine. Propofol also inhibited the depolymerization, but its concentration-dependent effect was not so clear. The antioxidant concentrations at which HA degradation was decreased by 50% were 42 microM for thiourea; 1.35 microM for vinpocetine; and 0.39 microM for propofol. A concentration of 26.51 mM of mannitol was needed to attain the same inhibitory effect. Although many factors are involved in a therapeutic response, the results obtained in this study support the idea that HA may be protected from ROS attack by the concomitant use of well-known antioxidants.