Anti-inflammatory effect of gallic acid-conjugated chitooligosaccharides in lipopolysaccharide-stimulated RAW 264.7 macrophages

The aim of the present study is to investigate the anti-inflammatory effect of gallic acid grafted onto COS chains (GA-COS), focusing on the reduction of nitric oxide production, downregulation of inflammatory signals such as inducible nitric oxide synthase (iNOS), gene expression of cytokines such as TNF-α, IL-1β, IL-6, and nuclear factor kappa B (NF-κB) signalling, including the p50 and p65 subunits. The anti-inflammatory effect is mediated through the reduction of nitric oxide production and downregulation of inflammatory proteins such as inducible nitric oxide synthase (iNOS), gene expression of cytokines like TNF-α, IL-1β, IL-6, and nuclear factor kappa B (NF-κB) signalling, including the p50 and p65 subunits. Target proteins were identified by western blot analysis with specific monoclonal antibodies. The levels of gene expression were determined by the RT-PCR method. The results demonstrate that GA-COS effectively reduces nitric oxide generation and downregulates iNOS protein and cytokine expression and NF-κB signalling in lipopolysaccharide (LPS) -induced RAW 264.7 cells. GA-COS exhibits significantly enhanced anti-inflammatory activity compared to the free chitooligosaccharide chain. This study lays the groundwork for future research to demonstrate that GA-COS holds significant potential as a novel compound for the prevention of inflammatory diseases.