Physicochemical Characterization of Polysaccharides with Macrophage Immunomodulatory Activities Isolated from Red Ginseng (Panax ginseng C. A. Meyer)

Abstract

In this study, four polysaccharide fractions designated as RGP1, RGP2, RGP3, and RGP4 were isolated from red ginseng by DEAE-52 cellulose chromatography, and their macrophage immunomodulatory activities were investigated. The results revealed that the proliferation, NO production, and neutral red phagocytosis of RAW 264.7 macrophage cells in groups treated with RGP1 and RGP2 in vitro were increased significantly compared to RGP3 and RGP4. In addition, the level of TNF-α in RAW 264.7 cells was significantly increased in RGP1 and RGP2 groups. All the results consistently indicated that polysaccharide fractions RGP1 and RGP2 had strong macrophage immunomodulatory activities. Furthermore, RGP1 and RGP2 were purified by Sephadex G-100 column and RGP2 was further fractionated into a homogeneous fraction RGP2-1, with the molecular weight of 2.16 × 104 Da. The analysis of monosaccharide composition revealed that RGP1 was composed of arabinose, glucose, and galactose with a relative molecular ratio of 0.02 : 0.88 : 0.10. RGP2-1 was composed of rhamnose, arabinose, glucose, and galactose with a relative molecular ratio of 0.02 : 0.10 : 0.77 : 0.11. These results provided evidences that the neutral polysaccharide fractions RGP1 and RGP2 possessed significant immunomodulatory activity and could be explored as a promising natural immunomodulating agent applied in functional foods or medicines.