Composition characterization of oyster polysaccharides from Crassostrea hongkongensis and their protective effect against H2O2-induced oxidative damage in IEC-6 cells

The proliferative activity of oyster polysaccharides in intestine epithelial cells (IEC-6) alleviated 5-fluorouracil-induced intestinal inflammation. In this study, we aimed to measure the ability of oyster polysaccharides to promote IEC-6 cell migration and antioxidant activity and further describe their cytoprotective effect on H2O2-challenged IEC-6 cells. The C30–60% fraction of polysaccharides (CHP2) showed rapid stimulation of IEC-6 cell migration after wounding. Then, CHP2 was fractionated into four fractions, namely, CHP2-1, CHP2-2, CHP2-3 and CHP2-4. The CHP2-3 fraction possessed high scavenging activities against 2,2′-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) (ABTS) and oxygen radical absorbance capacity (ORAC), in comparison with other fractions. And CHP2-3 was heteropolysaccharide with sulfuric esters, and it was mainly composed of glucose, galactose and arabinose and had an average molecular weight of 41.81 kDa. Pretreatment with CHP2 and CHP2-3 significantly improved the survival rate of H2O2-treated IEC-6 cells, and reduced intracellular reactive oxygen species (ROS) levels. Moreover, CHP2-3 also significantly decreased H2O2-mediated increases in the secretion of interleukin-1β (IL-1β) and interleukin-6 (IL-6), and attenuated nuclear factor-κB (NF-κB) p65 activation. These results indicate that CHP2-3 may play a vital role in reducing oxidative damage in IEC-6 cells via radical scavenging, decreasing proinflammatory factors secretion, inhibiting the NF-κB pathway, and thus, reducing cell apoptosis.