Conjugation of gallic acid onto chitosan: An approach for green and water-based antioxidant

A novel derivative of chitosan, chitosan–gallic acid (chitosan–GA), obtained from a simple conjugating condition with gallic acid using carbodiimide is proposed. The conjugation with gallic acid brings the water-solubility or water swelling property to chitosan. The studies on the free radical scavenging of chitosan–GA clarify its significant antioxidant activity on free radicals, i.e. carbon-centered radicals and hydroxyl radicals. Chitosan–GA clearly shows a synergistic antioxidant activity on hydroxyl radical scavenging where iron metals were involved. The work demonstrates how chitosan–GA can be a potential natural-compound-based antioxidant.