Structural characterization of a polysaccharide from Sargassum henslowianum, and its immunomodulatory effect on gastric cancer rat.

A complicated sulfated fucoidan, SHPPB2, was purified from Sargassum henslowianum by DEAE-cellulose 52 and Sephacryl S-300 column chromatography. Via chemical and spectral method, SHPPB2 was found to contain mannose, glucuronic acid, galactose, xylose, and fucose, in a ratio of 17.4: 13.5: 10.5: 16.8: 41.8, as well as 21.4% of sulfate. The methylation analysis demonstrated terminal, 3-, 4-, 2, 3-, and 3, 4- linked fucose, 2-, 2, 3-, 2, 4-, and 2, 4, 6- linked mannose, terminal, 4-, 6-, 2, 4-, 3, 4-, and 3, 6- linked galactose, terminal and 4- linked xylose, and 4- linked glucuronic acid. In addition, the sulfate groups were substituted on the C-2, C-3 or C-4 of 3- and 4- linked fucose, on the C-4 or C-6 of 2- linked mannose, and on C-2 or C-3 of 4- and 6- linked galactose. With the treatment of SHPPB2 in the N-methyl-N'-nitro-nitrosoguanidine (MNNG) induced gastric cancer rats, it was observed with an increased body weight, and improved immune organ indices. Furthermore, SHPPB2 could significantly promote splenocyte proliferation induced by ConA or LPS in gastric cancer rats, and improve anti-inflammatory cytokines (IL-2, IL-4, and IL-10) secretion, but reduce pro-inflammatory cytokines (IL-6 and TNF-α). Taken together, it suggested that SHPPB2 could improve immune function in gastric cancer rats. Thus, it could be explored as a potential immuno-therapy for gastric cancer treatment.