The Immunological And Antitumor Activities Of The Polysaccharides From The Root Of Panax Ginseng C.A. Meyer

Panax ginseng C.A. Meyer has long been used as a medicinal plant in Asian countries. It has been reported that P. ginseng polysaccharides have immunomodulating, anti-tumor, anti-adhesive, antioxidant and hypoglycemic activities. But there is still a lack of understanding of structure-activity relationship. Based on the total fractionation of ginseng polysaccharide, we detected the immunological and antitumor activity on both cell and animal levels.The water-soluble polysaccharides (WGP) were extracted from the roots of P. ginseng according to our previous method (extracted with hot water, precipitated by 80% ethanol and deproteinated using Sevag method). WGP was separated on a DEAE-Cellulose column into two fractions: a neutral fraction WGPN (eluted by water) and an acidic fraction WGPA (eluted by 0.5 M NaCl). WGPN was heterogenous starch-like glucan, and WGPA was a mixture of pectic polysaccharides. WGPA was further fractionated by DEAE-Cellulose ion-exchange chromatography and Sepharose CL-6B gel permeation chromatography, generating six homogenous fractions: WGPA-1-AG, WGPA-1-HG, WGPA-2-AG, WGPA-2-HG, WGPA-3-HG and WGPA-4-HG. Besides that, WGPA was treated by Endo-PG. The hydrolysates was fractionated by anion-exchange and gel-permeation chromatography, resulting in five rhamnogalacturonan I (RG-I) domains RG-I-1, RG-I-2, RG-I-3A, RG-I-3B and RG-I-4.WGP, WGPN and WGPA were tested for immune activity on normal mice, preliminary. The results showed that the three fractions can mediated both non-specific immune system and specific immune system on normal mice. It stimulated the proliferation of lymphocytes both in vitro and in vivo, increased NK and macrophage cell cytotoxic activity, enhanced the phagocytosis and NO production by macrophage.WGP, WGPN and WGPA were tested for antitumor and immunological activity on S180 sarcoma mice, secondly. The results showed ginseng polysaccharides can inhibit the growth of transplanted S180 tumor cells, but the anti-tumor effect of polysaccharide treatment group was much lower than the positive control group (cyclophosphamide administration). Meanwhile, ginseng polysaccharides could promote the immune systems of tumor bearing mice. The immunological activity pattern was coincidental between the S180 mice and the normal mice. Then these three fractions were combined with chemotherapy drug 5-fluorouracil (5-FU) respectively to observe whether there is a synergistic effect. The initial combination of WGPN and 5-FU showed a synergistic effect on.antitumor activity.The composition of WGPN is heterogenous starch-like glucans, and the yield of the WGPN was much more than WGPA. We designed an experiment to detect the antineoplastic effects and chemoprotective activity of WGPN. It was tested for anticancer activity alone and in combination with 5-fluorouracil (5-FU) in Sarcoma-180 (S180) bearing mice by intragastric administration (i.g.). WGPN alone inhibited S180 tumor growth in a dose-dependent manner among several testing doses, and the combination of WGPN with 5-FU showed a synergistic effect. Studies on various immunological activities of S180 bearing mice revealed that WGPN stimulated the proliferation of lymphocytes, enhanced the phagocytosis and NO production by macrophages, and increased the level of TNF-αin serum. In combination with 5-FU, WGPN mitigated damage to the immune system caused by 5-FU in S180 bearing mice. These results suggest that WGPN might be a potential adjuvant for chemotherapeutic drugs.WGPA was a mixture of pectic polysaccharides. A comparative study on immunological activity of different types of homogenous pectic fractions from WGPA was performed. Ginseng pectins stimulated the proliferation of lymphocyte, augment the phagocytosis of macrophages and increase TNF-α, IL-6 and IL-1 production of it. But there is no significant effect on H2O2 generation of macrophages. The activities of three types ginseng pectins were following this order: AG> RG-I> HG. Based on the monosaccharide composition, we deduced that the large amount of galacturonic acid in the homogalacturonan (HG) domains lead to less activity; the rhamnose moiety of rhamnogalacturonan may increase the immunological activity in some degree; AG exhibited the better activity on immune cells than HG and RG that may be due to the larger amount of Ara and Gal or the larger molecular weight. In addition, the macrophage phagocytic activity of WGPA was better than any of the homogenous polysaccharide fractions, suggesting that ginseng pectins may have a synergistic effect on macrophage phagocyticity.