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

► A water soluble polysaccharide (RAP-W1) was purified from Rhizoma Arisaematis. ► The anti-tumor and immunostimulatory activities of RAP-W1 have been demonstrated in mice models. ► RAP-W1 could significantly inhibit the growth of tumor transplanted in mice. ► RAP-W1 could improve body weight, spleen index and CTL activity. ► RAP-W1 could up-regulate Th1/Th2 cytokine ratio in the serum of tumor-bearing mice.