Purification, structural characterization and in vitro antioxidant activity of a novel polysaccharide from Boshuzhi

A novel polysaccharide, designated GCPB-1b, was obtained from the alkaline extract of the submerged fermentation culturing mycelium powder of Boshuzhi, Ganoderma capense. This polysaccharide was purified by ion-exchange and gel-permeation column chromatography and is a glucan (MW 2847 Da). GCPB-1b has a specific optical rotation of [alpha](D)(25) =+154 degrees (c 1.0, H2O). Based on monosaccharide analysis, partial acid hydrolysis, periodic acid oxidation-Smith degradation, methylation analysis, Fourier transform-infrared spectroscopy (FT-IR), gas chromatography-mass spectrometry (GC-MS) and nuclear magnetic resonance (NMR) spectroscopy, the backbone of GCPB-1b was composed of (1 -> 4)-linked-alpha-D-glucose residues and (1 -> 4,6)-linked-alpha-D-glucose residues. Furthermore, GCPB-1b had 1-dipheny1-2-picryl-hydrazyl (DPPH center dot) radical-scavenging ability (EC50 3.23 mu M) according to antioxidant activity tests which was greater than other antioxidants. These data suggest that GCPB-1b holds promise as an anti-aging functional food. (C) 2016 Elsevier Ltd. All rights reserved.