In relation, cross-linked HA gel and HMW HA were evaluated in vitro for antioxidant activity using xanthine oxidase/hypoxanthine as a source of free radicals (superoxide, O2-).
The amount of free radicals consumed was determined by monitoring the increase in absorbance, at 550 nm, caused by the reduction of cytochrome c. In the presence of a free radical scavenger, absorbance is decreased due to the removal (scavenging) of free radicals by a particular agent.