Production of chitin oligosaccharides with different molecular weights and their antioxidant effect in RAW 264.7 cells

The purpose of this research is not only to produce two kinds of chitin oligosaccharides or N-acetyl chito-oligosaccharides (NA-COSs) with different molecular weights (MW) from crab chitin hydrolysis solution but also to determine their effect against oxidative stress in live cells. Two kinds of NA-COSs with MW 1–3 kDa (NA-COS 1–3 kDa) and below 1 kDa (NA-COS < 1 kDa) were obtained using an ultrafiltration membrane system. They exhibited an inhibitory effect against DNA and protein oxidation. In addition, in their presence, intracellular glutathione (GSH) level and direct intracellular radical scavenging effect were significantly increased in a time-dependent manner in mouse macrophages (RAW 264.7) and rendered inhibitory effect against cellular oxidative stress. In particular, NA-COS 1–3 kDa was more effective than NA-COS < 1 kDa in protein oxidation and production of intracellular free radicals in live cells. These results suggest that NA-COSs act as a potential scavenger against oxidative stress in cells.