Structural characterization of a polysaccharide from Chrysanthemum morifolium flowers and its antioxidant activity

•A novel polysaccharide CMJA0S2 was isolated and purified from Chrysanthemum morifolium flowers.•The structure of CMJ0S2 formed with a manogalactoglucan backbone was elucidated.•The polysaccharide CMJA0S2 exhibited significant anti-oxidative effect. The flowers of Chrysanthemum morifolium were extracted by boiling water, and a water-soluble polysaccharide (CMJA0S2) with a molecular weight of 6.5kDa was isolated by anion-exchange chromatography on a DEAE-cellulose column and gel permeation chromatography on a Sephacryl S-300 HR column. Monosaccharide composition analysis indicated that CMJA0S2 was composed of galactose, glucose, mannose and arabinose in molar ratio of 4.1: 3.3: 1.0: 2.3. According to linkage analysis, partial acid hydrolysis and NMR spectra, the backbone was shown to contain 1, 4-linked β-Galp, 1, 4-linked β-Glcp and 1, 4-linked β-Manp, with branches substituted at C-6 of 1, 4-linked β-Manp by 1, 6-linked β-Galp and at O-6 of partial 1, 4-linked β-Galp substituted by T-linked α-Glcp. About 40% of 1, 6-linked β-Galp with T-linked α-Glcp was substituted at O-3 by α-Araf-(1→[5)-α-Araf-(1]3. The anti-oxidative analysis showed that CMJA0S2 could scavenge the DPPH radicals and relieve the damage of PC12 cells caused by H2O2, thus it could be regarded as a potential natural antioxidant.