Protective effects of sulfated chitooligosaccharides with different degrees of substitution in MIN6 cells

Chitosan, a naturally occurring biopolymer, has received considerable attention for pharmaceutical applications due to its biocompatible, biodegradable and less toxic properties. In this study, sulfated chitooligosaccharides (COS-S) with different degrees of substitution (DS) were prepared to improve both its water-solubility and bioactivity. Additionally, the protective effects of COS-S on hydrogen peroxide (H2O2)-induced dysfunction in MIN6 cells were investigated. COS-SI (DS, 0.8) and COS-SII (DS, 1.9) significantly increased the cell viability in a dose-dependent manner. COS-S also significantly suppressed NO production, the activity and mRNA expression of iNOS, and the protein level of NF-κB protein p65, which were activated by H2O2. Furthermore, we demonstrated that COS-S led to an increase in the Bcl-2/Bax mRNA expression ratio and the inhibition of Caspase-3 mRNA expression in H2O2-stimulated MIN6 cells. Additionally, COS-SII (DS, 1.9) exhibited a superior protective effect on H2O2-induced apoptosis compared to COS-SI (DS, 0.8). These results indicated the good anti-oxidative capacity of COS-S and the possible mechanism via the blockade of the NF-κB signaling pathway. The protective effects of COS-S against oxidative injuries in MIN6 cells were depended on both DS and concentration.