Isolation, molecular characterization and antioxidant activity of a water-soluble polysaccharide extracted from the fruiting body of Termitornyces albuminosus (Berk.) Heim.

A water-soluble polysaccharide WSP1 was extracted from the fruiting body of Termitornyces albuminosus. Its molecular weight, monosaccharide composition and molecular structure were determined by GPC, GC-MS, UV spectroscopy, FT-IR spectroscopy, methylation analysis, NMR (1D and 2D) and AFM. Moreover, the antioxidant activity of WSP1 was evaluated in vitro by the tests of reducing power, scavenging ability on DPPH radical and hydroxyl radical, and chelating ability on ferrous ion. The results indicated that the molecular weight of WSP1 was 9 kDa, and it was mainly composed of fucose and galactose in a molar ratio of 1:3.09. Based on monosaccharide composition, methylation analysis and NMR, the possible repeating unit of WSP1 was presented as follows: →2-α-l-Fucp-1→ (6-α-d-Galp-1)3→. The antioxidant assay revealed that, in the concentration range tested in this experiment, WSP1 had strong scavenging ability on DPPH radical, suggesting that WSP1 could be potentially used as a powerful radical scavenger.