Abstract
Oxidative stress induced by free radicals is a major factor in cell damage and is responsible for various kinds of diseases. Naturally abundant, chitosan is a perspective cationic polysaccharide which demonstrates scavenging free radical and antioxidant activity.
Its antioxidant activity and water solubility depends on the molecular weight and degree of deacetylation. Even if the exact mechanism of activity is unknown, it is assumed that an amino group and hydroxyl groups react with unstable free radicals to form more stable macromolecular radicals.
Efforts to improve the antioxidant activity of chitosan led to the grafting of natural or synthetic antioxidant molecules on chitosan. Modification of chitosan molecule by carboxymethylation, quaternization, sulphation, sulphonation, and Schiff base preparation brings more active derivatives.
The most frequently used antioxidants, like phenolic compounds, gallic acid, caffeic acid, substituted hydroxyanisole, hydroxytoluene, and green tea extracts were incorporated into the chitosan molecule to improve its antioxidant activity.