Structural characteristics of a novel polysaccharide purified from ginseng and the anti-insulin resistance effects on HepG2 cells

Abstract Ginseng polysaccharides have attracted research interest for their pharmacological value. In this study, the simplified combination of DEAE cellulose-52 ion-exchange column and ultrafiltration was designed to isolate a novel polysaccharide named GPA-G3-H from ginseng. The main components of GPA-G3-H were determined to be glucose, galacturonic acid, galactose, and arabinose. The structure of GPA-G3-H was further comprehensively characterised by zeta potential analysis, NMR, X-ray diffraction, and GCMS. GPA-G3-H existed in the semi-crystalline state, with its backbone predominantly composed of 1,4-Glcp and 1,3,6-Galp. Moreover, GPA-G3-H possessed high content of galactose and uronic acid, uniform molecular size, plentiful negative charge, and the highly branched structure. The radical scavenging experiments showed GPA-G3-H had excellent antioxidant activity. In vitro studies further revealed that GPA-G3-H could attenuate insulin resistance by increasing PK and HK activity, suppressing G6Pase and PEPCK activity in IR-HepG2 cells. These findings indicate that GPA-G3-H holds significant promise as both an antioxidant and functional food ingredient.