A new water-soluble polysaccharide from Echinops pungens Trautv roots. Part I. Isolation, purification, characterization and antioxidant activity

EPPS, a new heteropolysaccharide from Echinops pungens roots, was extracted by warm water (70 degrees C) and fortuitously purified using column chromatographies on DEAE-cellulose A52 and Sephadex G-100. Total carbohydrate content, specific optical rotation and molecular mass of EPPS were 98.3%, -88.2 and 65.7 kDa, respectively. GLC analysis revealed that EPPS was a neutral polysaccharide and contained Gal, Glc, Man, Xyl, and Ara at ratios of 0.96: 523:1.00:2.06:1.04. Multiple chemical and instrumental analysis methods such as methylation, periodate oxidation and Smith degradation, partial acid hydrolysis, GLC-MS, FT-IR and NMR (H-1 and C-13) were employed to elucidate the structure of EPPS and their results showed that its backbone consists of -> 6)-beta-D-Glcp-(1 -> residues, with branches attached to 0-4 (similar to 38%) by -> 4)-beta-L-Arap-(1 ->, -> 4)-beta-D-Manp-(1 ->, -> 4)-beta-D-Xylp-(1 ->, beta-D-Xylp-(1 -> and alpha-D-Galp-(1 -> residues. DPPH radical scavenging ability of EPPS was lower than ascorbic acid at identical concentrations and its EC50 value was 1.91 mg/ml. (C) 2018 Elsevier B.V. All rights reserved.