Antioxidant properties of chitosan from crab shells

Crab chitosan was prepared by alkaline N-deacetylation of crab chitin for 60, 90 and 120 min and its antioxidant properties studied. Chitosan exhibited showed antioxidant activities of 58.3-70.2% at 1 mg/mL and showed reducing powers of 0.32-0.44 at 10 mg/mL. At 10 mg/mL. the scavenging ability of chitosan C60 on 1,1-diphenyl-2-picrylhydrazyl radicals was 28.4% whereas those of other chitosans were 46.4-52.3%. At 0.1 mg/mL, scavenging abilities on hydroxyl radicals were 62.3-77.6% whereas at 1 mg/ml. chelating abilities on ferrous ions were 82.9-96.5%. All EC50 values of antioxidant activity were below 1,5 mg/mL. With regard to antioxidant properties assayed, the effectiveness of chitosans C60, C90 and C120 correlated with their N-deacetylation times. Overall, crab chitosan was good in antioxidant activity, scavenging ability on hydroxyl radicals and chelating abilities on ferrous ions and may be used as a source of antioxidants, as a possible food Supplement or ingredient in the pharmaceutical industry. (C) 2008 Elsevier Ltd. All rights reserved.