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

► A homogeneous polysaccharide (RRP-ws) was purified from Rhodiola rosea. ► RRP-ws had a potent tumor growth inhibition effect in vitro and in vivo. ► RRP-ws increased the relative spleen/thymus indexes and body weight. ► RRP-ws also increased the production of IL-2, TNF-α, and IFN-γ in serum. ► RRP-ws elevated the ratio of CD4+/CD8+ T lymphocyte in tumor bearing mice peripheral blood.