Structural analysis of water-soluble polysaccharides isolated from Panax notoginseng

Panax notoginseng is a widely used traditional Chinese medicine and has extensive pharmacological effects. In this work, water-soluble polysaccharides from Panax notoginseng were isolated and fractionated. One starch-like polysaccharide (PNPN) and six pectin fractions (PNPA-1A, PNPA-1B, PNPA-2A, PNPA-2B, PNPA-3A and PNPA-3B) were obtained. Monosaccharide composition, enzymatic hydrolysis, nuclear magnetic resonance and methylation analysis were combined to characterize their structures. PNPA-1A and PNPA-2A mainly contained 1,4-β-D-galactans, 1,5-α-L-arabinan and arabinogalactan II (AG-II). PNPA-3A was a typical rhamnogalacturonan I (RG-I) type pectin with 1,4-β-D-galactan and 1,5/1,3,5-α-L-arabinan side chains. PNPA-1B, PNPA-2B and PNPA-3B consisted of homogalacturonan (HG) as major domains, together with different ratios of RG-I and rhamnogalacturonan II (RG-II) domains. These results will provide basis for further investigation of structure-activity relationships of Panax notoginseng polysaccharides and be useful for the application of Panax notoginseng.