Characterization and antitumor activities of the water-soluble polysaccharide from Rhizoma Arisaematis

A water soluble polysaccharide (RAP-W1) was purified from Rhizoma Arisaematis and its antitumor activity was evaluated in BALB/c mice bearing human breast cancer MCF-7. RAP-W1 had the following physicochemical properties: total carbohydrate content (95.9%); no protein; molecular weight (≈57 kDA); monosaccharides composition (rhamnose:fucose:arabinose:mannose:galactose:glucose=0.4:0.5:0.3:0.6:0.9:5.3). After 14 days' treatment to tumor-bearing mice, RAP-W1 could significantly inhibit the growth of tumor transplanted in mice and increase the body weight and the spleen index. Moreover, RAP-W1 could significantly stimulate Con A- or LPS-induced splenocyte proliferation in tumor-bearing mice, as well as enhance the CTL activity. The level of Th1 cytokines (INF-γ and IL-2) in the serum of tumor-bearing mice was increased by RAP-W1 treatment, whereas the Th2 cytokine (IL-10) secretion displayed a dramatic reduction. All the data implied that RAP-W1 can activate T cells by up-regulating Th1/Th2 cytokine ratio, which might partially cause the inhibition of tumor growth.