Preparation of chitooligosaccharide acetate salts with narrow molecular size distribution and the antioxidative activity

Wide molecular weight distribution leads to uncertainties about the activity of chitooligosaccharide (COS). In the study, COS acetate salts with narrower size distribution were prepared in kilogram scale. The excellent water solubility and non-crystalline polysaccharide structure of COS products were observed. Furthermore, the antioxidative test results showed that the concentration of COS acetate salts exceeding 3 mg/mL was efficient for inhibiting free radicals and protecting human umbilical vein endothelial cells (HUVECs) against oxidative stress. Additionally, molecular weight of COS acetate played an important role in exerting antioxidative activity. COS acetate salt with M w (weight average molecular weight) 41.2 or 4.22 kDa showed better radical scavenging activity and reducing power. Moreover, the cellular assay results suggested that COS acetate salts could significantly suppressed the reduction in cell viability under severe oxidative stress, especially that with M w 11.5 kDa. In conclusion, COS acetate salts with narrow M w distribution can be prepared in large scale and used as natural antioxidant, with the potential for preventing cardiovascular diseases.