Caffeic acid-grafted chitooligosaccharides downregulate MAPK and NF-kB in RAW264.7 cells

Chitooligosaccharide (COS) is a derivative of chitosan, which is a natural macromolecular compound. COS has been shown effects in an inflammatory response. Recent reports show that COS derivatives have enhanced anti-inflammatory activity by inhibiting intracellular signals. Evaluation of the anti-inflammatory effect of caffeic acid conjugated COS chain (CA-COS) was performed in this study. The effects of CA-COS on the inflammatory response were demonstrated in lipopolysaccharide-stimulated RAW264.7 macrophages. The results showed that CA-COS inhibited nitric oxide (NO) production and downregulated the gene expression of nitric oxide synthase (iNOS), and cytokines such as tumor necrosis factor-alpha (TNF-α), IL-1β, and IL-6 without cytotoxic effect. In addition, western blot analysis showed that CA-COS inhibits the protein expression of iNOS and nuclear factor kappa B (NF-kB), including p50 and p65, and mitogen-activated protein kinase (MAPK) signaling pathways. Collectively, these results provide clear evidence for the anti-inflammatory mechanism of CA-COS that show great potential as a novel agent for the prevention and therapy of inflammatory diseases.