Stereospecificity of Ginsenoside Rg3 in the Promotion of Cellular Immunity in Hepatoma H22-Bearing Mice

Previous investigations have demonstrated that ginsenoside Rg3 (Rg3) has many actions including antitumor, antioxidative, and immunomodulatory effects. However, Rg3 exists as 2 stereoisomeric pairs, 20(S)-ginsenoside Rg3 [20(S)-Rg3] and 20(R)-ginsenoside Rg3 [20(R)-Rg3], which have disparate pharmacological actions because of their different chemical structures. In this study, the 2 epimers were compared for their effects on the growth of hepatocellular carcinoma H22 transplanted tumors and the immune function of H22-bearing mice. In vivo efficacy study showed that the growth of H22 transplanted tumors was significantly inhibited when treated with 20(S)-Rg3 and 20(R)-Rg3 (P < 0.05), and the inhibition rate of tumor growth was 23.6% and 40.9%, respectively. Furthermore, the cellular immunity of H22-bearing mice was remarkably enhanced after Rg3 treatment (P < 0.05), which may be due to stimulation of ConA-induced lymphocyte proliferation and augmentation of Th1-type cytokines interleukin-2 and interferon-gamma levels in mice. Interestingly, the effects of 20(R)-Rg3 were significantly greater than those of the S-form (P < 0.05). Taken together, these results indicate that Rg3 inhibits H22 tumor growth in vivo at least partly by improving the host's cellular immunity in a stereospecific manner, and 20(R)-Rg3 is more potent for treating cancers or other immune-mediated diseases clinically.