Antioxidant Activities of Enriched Polysaccharide Fractions from Mycelia of Amauroderma subresinosum

Abstract

The polysaccharides found in Amauroderma subresinosum have been recognized, but their characterization has been limited. In this study, enriched polysaccharide fractions (ASF) were extracted from the mycelia of Amauroderma subresinosum using hot water, sodium hydroxide, and acetone. To determine these ASF structural characteristics, deproteination and precipitation with cold ethanol were performed to remove residual proteins. Fourier transform infrared (FTIR) spectroscopy was employed to assess the purity of the ASF, while gel permeation chromatography (GPC) was used to measure molecular weight, and high-performance liquid chromatography with precolumn derivatization using 1-phenyl-3-methyl-5-pyrazolone (PMP) reagent was utilized for monosaccharide analysis. The antioxidant activity of the ASF was evaluated through DPPH and ABTS radical scavenging assays. Seven enriched polysaccharide fractions, named ASF1-7, were isolated, and three main fractions were identified as ASF-1 (22.53 kDa, 6.16 ± 1.01%, w/w), ASF-3 (0.75 kDa, 16.46 ± 0.26%, w/w), and ASF-7 (35.73 kDa, 12.60 ± 1.48%, w/w). These fractions corresponded to the primary polysaccharide derived from hot water, alkaline solution, and insoluble residue. Monosaccharide analysis revealed that glucose was the predominant component in ASF-1 (70.24%), ASF-3 (84.11%), and ASF-7 (87.78%). FTIR spectroscopy confirmed the presence of carboxyl and hydroxyl groups, as well as pyranose rings in these ASFs. Additionally, ASF-1, ASF-3, and ASF-7 demonstrated significant DPPH and ABTS radical scavenging activities, with IC50 values ranging from 12.8 to 16.1 µg/mL and 8.5 to 12.6 µg/mL, respectively. This study provides the initial evidence that polysaccharides extracted from Amauroderma subresinosum may possess potential as functional food ingredients with potent antioxidant activity.