Structural characteristics of a RGAP (red ginseng acidic polysaccharide), rhamnogalacturonan I with immuno-stimulating activity from red ginseng

This study aimed to characterize the immunostimulatory and structural properties of red ginseng acidic polysaccharide (RGAP; Panax ginseng Meyer), a polysaccharide fraction (RGP-AP) isolated from red ginseng via hot water extraction followed by amylase and, subsequently, pectinase digestion and ethanol precipitation. Next, a complex acidic polysaccharide (RGP-AP-I) was purified to homogeneity from RGP-AP via size-exclusion chromatography using Sephadex G-100. 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 characteristic of rhamnogalacturonan I (RG-I). Based on the results of oligosaccharide analyses, we assumed that the immunostimulatory activity of RGP-AP-I may be due to the RG-I structure, ...
Source: Journal of Ginseng Research - Category: Complementary Medicine Source Type: research