Antitumor effects of a purified polysaccharide from Rhodiola rosea and its action mechanism.

In the last three decades, numerous polysaccharides and polysaccharide-protein complexes have been isolated from plant or animal and used as a promising source of therapeutic agents for cancer. In this study, we prepared a homogeneous polysaccharide (RRP-ws) from Rhodiola rosea and tested its immunomodulation and anti-cancer activity in vitro and in vivo experiments using Sarcoma 180 (S-180) cells. Preliminary physicochemical analysis identified that RRP-ws was composed of Glc, Gal, Man and Rha with a relative molar ratio of 4.2:2.4:1.6:1.0, and contained 95.14% of total carbohydrate, 2.08% of protein and no sulfate. In vitro experiment showed that RRP-ws exerted a direct cytotoxic effect on the growth of S-180 cells. In vivo experiment, RRP-ws could inhibit tumor growth of S-180 tumor transplanted in mice, and increase the relative spleen/thymus indexes and body weight. Furthermore, RRP-ws also increased the production of IL-2, TNF-α and IFN-γ in serum, and elevated the ratio of CD4+/CD8+ on peripheral blood T-lymphocyte in tumor bearing mice. The overall findings indicated that RRP-ws could be used as a novel promising immunotherapeutic agent in cancer treatment.