A heteropolysaccharide from Saccharina japonica with immunomodulatory effect on RAW 264.7 cells

A heteropolysaccharide (SHP) with a strong immunomodulatory effect on RAW 264.7 cells was prepared from Saccharina japonica. Chemical analysis demonstrated that SHP was primarily composed of mannose, glucuronic acid, glucose, fucose, galactose, xylose and rahmnose with a molar ratio of 1.00:0.85:0.84:0.58:0.30:0.37:0.15. ESI-MS showed that depolymerized SHP produced oligo-glucuronan, oligo-glucuronomannan, sulfated fuco-oligosaccharides and other hetero-oligosaccharides. The in vitro immunomodulatory results showed that SHP could increase NO production and up-regulate the expression of many immune effectors, including iNOS, COX-2 and TNF-α, displaying an apparent immune enhancement activities. Western blot analysis proved that SHP activated the expression levels of many key components involved in NF-κB, MAPK and Akt signaling pathways. Our results together indicated that SHP has the potential to be developed as a novel immunomodulator for activating immune system.