Structural characterization and RAW264.7 murine macrophage stimulating activity of a fucogalactoglucan from Colpomenia peregrina.

Water-soluble polysaccharides were isolated from Colpomenia peregrina to determine their chemical characteristics and immunomodulatory properties. High extraction yields were obtained for CP1 (17.6%) and CP2 (5.2%) polysaccharides. Polysaccharides were mainly consisted of neutral sugars (67.01-73.79%), uronic acids (9.43-14.89%), proteins (3.44-14.89%) and small amounts of sulfates (4.87-4.91%). Polysaccharides were composed of fucose (20.62-24.56%), galactose (25.5-26.94%) and glucose (50.00-52.91%) residues. The average molecular weights of the CP1 and CP2 polysaccharides were 1890 × 103 g/mol and 639 × 103 g/mol, respectively. The polysaccharides exerted a relatively low cytotoxicity against HeLa cancer cells (< 40%). The CP1 and CP2 polysaccharides were nontoxic and induced RAW264.7 murine macrophage cells to release considerable amounts of nitric oxide (NO). Inflammatory cytokines including IL-1β, TNF-α, IL-6, IL-10 and IL-12 from were secreted from RAW264.7 cells induced with CP1 polysaccharides. As the most immunostimulating fraction, CP1 polysaccharides were homogeneous and formed of 1,3-linked galactose, 1,4-linked glucose and 1,3-linked fucose residues. Overall, these findings suggested that the polysaccharides isolated from C. peregrina can be utilized as potential natural immunostimulant in functional foods or pharmaceutical industries.