Chitosan oligosaccharides attenuate hydrogen peroxide-induced stress injury in human umbilical vein endothelial cells

Chitosan oligosaccharides (COS) have been reported to have anticancer activity, immuno-enhancing effect and antimicrobial activity. However, other biological activities are unknown. Herein, we investigated the protective effects of COS against hydrogen peroxide (H2O2)-induced oxidative damage on human umbilical vein endothelial cells (HUVEC, ECV304 cells). After 24 h pre-incubation with COS (25-200 mu g/ml), the viability loss in ECV304 cells induced by H2O2(300 mu M) for 12 h was markedly restored in a concentration-dependent manner as measured by MTT assay. This effect was accompanied by a marked decrease in intracellular reactive oxygen species (ROS) by measuring intensity of DCFH fluorescence. COS also exerted preventive effects on suppressing the production of lipid pet-oxidation such as malondialdehyde (MDA), restoring activities of endogenous antioxidants including superoxide dismutase (SOD) and glutathione peroxidase (GSH-Px), along with the capacity of increasing levels of nitric oxide (NO) and nitric oxide synthase (NOS), as were determined by commercial regent kits. In addition, pre-incubation of COS with ECV304 cells for 24 h resulted in the reduction of apoptosis and the induction of cell cycle arrest in G(1)/S + M phase as assayed quantitatively by Annexin V-fluorescein isothiocyanate (FITC) apoptosis detection kit using flow cytometry. Taken together, Our findings suggest that COS can effectively protect HUVECs against oxidative stress by H2O2, which might be of importance in the treatment of cardiovascular diseases. (C) 2008 Elsevier Ltd. All rights reserved