Structural characteristics of a red ginseng acidic polysaccharide, rhamnogalacturonan-I, with immunostimulating activity from red ginseng

This study aimed to characterize the immunostimulatory and structural properties of the 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–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 a 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. Based on the results of oligosaccharide analyses, we assumed that the immunostimulatory activity of RGP-AP-I may be due to the rhamnogalacturonan-I stru...
Source: Journal of Ginseng Research - Category: Complementary Medicine Source Type: research