RADICAL-FREE RADICAL-SCAVENGING ACTIVITIES OF LOW MOLECULAR WEIGHT CHITIN OLIGOSACCHARIDES LEAD TO ANTIOXIDANT EFFECT IN LIVE CELLS

Chitin oligosaccharides (NA-COS) with low molecular weight distribution of 229.21-593.12 Da were produced from crab chitin by acid hydrolysis. They showed reducing power and scavenging effect on 1,1-diphenyl-2-picrylhydrazyl (DPPH) (Sigma Chemical Co., St. Louis, MO), hydroxyl and alkyl radicals. It was observed that the radical-scavenging activity of NA-COS increased in a dose-dependent manner. Their IC50 values for DPPH, hydroxyl and alkyl radicals were 0.8, 1.75 and 1.14 mg/mL, respectively. Furthermore, NA-COS exhibited the inhibitory effect on the oxidative damage of DNA from human lymphoma U937 (American Type Culture Collection, Manassas, VA) and the direct radical-scavenging effect in human fibrosarcoma cells (HT1080) (American Type Culture Collection) in 2',7'-dichlorofluorescin diacetate (DCFH-DA) assay (Molecular Probes Inc., Eugene, OR). The results suggest that NA-COS can exert antioxidant effect in live cells and have the potential to be applied to food supplements or nutraceuticals.