Structural characterization of a new water-soluble polysaccharide isolated from Acanthophyllum acerosum roots and its antioxidant activity

A new water-soluble polysaccharide named as AAPS-1, was extracted with warm water from the roots of Acanthophyllum acerosum and further purified by DEAE-cellulose A52 anion-exchange and Sephadex G-50 gel filtration chromatography. AAPS-1 was a neutral polysaccharide, with a molecular weight of 23.2 kDa and a specific optical rotation of+181.3 degrees (c 1.0, H2O), and comprised of Glucose, Galactose and Arabinose with a relative molar ratio of 1.6:5.1:1.0. Structure features of AAPS-1 were investigated by a combination of chemical and instrumental analysis, such as partial acid hydrolysis, methylation, periodate oxidation and Smith degradation, GC-MS, FTIR and NMR (C-13 and H-1). The data obtained indicate that AAPS-1 possessed a backbone of -> 6)-alpha-D-Galp-(1 -> residues, with branches attached to O-2 (similar to 35%) by alpha-D-Glcp-(1 -> and at O-3 (similar to 16%) by alpha-D-Galp-(1 -> and by beta-L-Arap-(1 -> 3)-beta-L-Arap-(1 -> 3)-beta-L-Arap-(1 -> The scavenging activity of AAPS-1 against DPPH radical was less than that of ascorbic acid at the same concentrations and the EC50 value of AAPS-1 was 1.4 mg/ml. (C) 2017 Elsevier B.V. All rights reserved.