Structural characterization of an antioxidant polysaccharide isolated from the fruiting bodies of Lyophyllum decastes

Abstract

It is well known that mushroom-derived compounds have numerous medicinal/bioactivities, such as immunomodulatory, antidiabetic, antiviral, antimicrobial, hepatoprotective and antitumor activities. In the current study, we investigate the purification, structural characteristics, and anti-oxidation activity of Lyophyllum decastes polysaccharide. A new polysaccharide, LDSP60-A, was isolated from the fruiting bodies of L. decastes using hot water extraction, ethanol precipitation and chromatography. Chemical structural analysis showed that this polysaccharide is mainly composed of D-glucose and D-galactose (in the ratio of 1.00:0.64, with a molecular weight of 6.18 × 105 Da). Methylation analysis, one-dimensional 1H- and 13C- nuclear magnetic resonance (NMR) and two-dimensional NMR spectroscopy revealed that LDSP60-A has a β-1,6-D-glucopyranose (Glcp) backbone and with a minor terminal-D-Glcp and 1,6-D-galactopyranose (Galp). The antioxidant activity of LDSP60-A, evaluated by 2,2-diphenyl-1-picrylhydrazyl (DPPH) and 2,2′-azino-bis (3-ethylbenzothiazoline-6-sulfonic acid) (ABTS+) free radical scavenging, showed that it had a high antioxidant activity with the activity for scavenging DPPH and ABTS+ free radicals of up to 78.6% and 97.33% at concentrations of 1.2 and 0.8 mg/mL, respectively. These results provide useful information for developing L. decastes polysaccharide-related foods and promote application of the L. decastes in the pharmaceutical and functional food industries.