RESUMEN
Two acidic polysaccharides (GP-B1 and GP-C1) were obtained from Gynostemma pentaphyllum. The molecular weights (Mw) of the two fractions were 79 kDa for GP-B1 and 126 kDa for GP-C1. GP-B1 was composed of Gal, Ara, Man, Rha, Xyl, Glc, GalA and GlcA in a molar ration of 3.5:3.2:0.6:0.9:0.3:0.5:0.6:0.4. GP-C1 consisted of Gal, Ara, Man, Rha, Glc, and GlcA in the proportions of 2.1:1.0:0.3:0.5:0.4:0.9. Among them, GP-B1 treatment had a significant inhibitory effect on the growth of melanoma B16 in vivo and in vitro. Meanwhile GP-B1 could increase the relative spleen weight and stimulate the splenocyte proliferation alone or combined with ConA. Moreover, GP-B1 treatment induced an evident increase in the level of serum TNF-α, IFN-γ, and IL-12 and a reduction for IL-10 production. These results indicate that the antitumor effects of GP-B1 are associated with immunostimulation.