Panax ginseng has long been used as natural medicine and health food all over the world. Cancer is a major cause of death worldwide and its prognosis likely depends on the immune system during tumor treatment. In this study, ginseng berry polysaccharides were evaluated for their immunostimulant and anti-cancer effects. Ginseng berry polysaccharide portion (GBPP) was used to investigate its effects on anti-complementary activity, peritoneal macrophage activation, and natural killer (NK) cell cytotoxicity. Moreover, both intravenous (i.v.) and oral administration of GBPP prior to B16-BL6 melanoma implantation in mice was evaluated. GBPP significantly increased the anti-complementary activity and cytokine production including interleukin (IL)-6, IL-12, and tumor necrosis factor (TNF)-α, dose-dependently. Splenocytes obtained after i.v. administration of GBPP showed cytolytic activity in Yac-1 cells in proportion to the E/T ratio. In addition, GBPP enhanced the production of interferon (IFN)-γ and granzyme B of NK cells. For the experimental lung cancer, compared with control mice, GBPP delivered by i.v. suppressed cancer by 48% at 100 μg/mouse, while a 37% reduction was achieved by oral administration. Deficient of NK cells in animal model demonstrated that the anti-cancer effect of GBPP was through NK cell activation. Results of this study suggest that ginseng berry polysaccharides, owing to their modulation of the immune response, can be a potential curative applicant for the prevention and treatment of tumors.

Many researchers reported that the various immune activities of red ginseng are due to acid polysaccharides. But, the exact structural characteristics of the acidic polysaccharide in red ginseng have not been fully elucidated. Therefore, we isolated the acidic polysaccharide from red ginseng and characterized the structural property of the active moiety of this polysaccharide, which contributes to the immunostimulatory activity of red ginseng. A polysaccharide (RGP-AP-I) was purified from red ginseng via size-exclusion chromatography using Sephadex G-100. Immunostimulatary activity of RGP-AP-I was investigated via anti-complementory and macrophage stimulatory activity. The structure of RGP-AP-I was characterized by HPLC, sugar composition, β-glucosyl Yariv reagent and methylation analysis. Peritoneal macrophages stimulated using RGP-AP-I significantly augmented the production of various cytokines such as interleukin (IL)-6, IL-12, and tumor necrosis factor (TNF)-α. The primary structure of RGP-AP-I was elucidated by assessing its sugar composition and methylation analysis. RGP-AP-I is a 96 kDa acidic polysaccharide, and comprises nine different monosaccharides, which mainly include sugars such as rhamnose (Rha, 9.5%), galacturonic acid (GalA, 18.4%), galactose (Gal, 30.4%), and arabinose (Ara, 35.0%). RGP-AP-I exhibited an considerable reaction with the β–glucosyl Yariv reagent, revealing the presence of arabino-β-3,6-galactan. Methylation analysis indicated that RGP-AP-I comprises 21 different glycosyl linkages, such as 3-, 4-, 6- and 3,6-linked Galp; 5-linked Araf; 2,4-linked Rhap; and 4-linked GalAp, which are characteristics of rhamnogalacturonan I (RG-I). we assumed that the immunostimulatory activity of RGP-AP-I may be due to the RG-I structure, which comprises a main chain with a repeating linkage unit, [→2)-Rhap-(1→4)-GalAp-(1→] and three groups of side chains such as (1→5)-linked arabinan, (1→4)-linked galactan, and arabino-β-3,6-galactan, which branch at the C(O)4 positions of Rha residues in the main chain of RGP-AP-I.