Fucoidan inhibits lipopolysaccharide-induced inflammatory responses in RAW 264.7 macrophages and zebrafish larvae

Fucoidan, a sulfated polysaccharide, is an active component found in various species of seaweed. Although this compound has a strong anti-inflammatory activity, the underlying mechanisms exerted by fucoidan have not been fully elucidated. In the present study, the anti-inflammatory effects of fucoidan on lipopolysaccharide (LPS)-stimulated macrophages and zebrafish larvae were examined. The present data indicated that fucoidan significantly suppressed the secretion of pro-inflammatory mediators including nitric oxide (NO) and prostaglandin E₂ (PGE₂), and cytokines, such as tumor necrosis factor-α and interleukin-1β in RAW 264.7 macrophages without any significant cytotoxicity, the protective effects of which were accompanied by a marked reduction in their regulatory gene expression at the transcription levels. Fucoidan also inhibited translocation of the nuclear factor-kappa B from the cytoplasm to the nucleus and attenuated LPS-induced production of intracellular reactive oxygen species (ROS) in RAW 264.7 macrophages. Moreover, fucoidan reduced NO and PGE₂ production and ROS accumulation in LPS-stimulated zebrafish larvae, which was associated with a diminished recruitment of neutrophils and macrophages. Based on the results of this study, we suggest that fucoidan has excellent potential as a therapeutic agent for inflammatory disorders.