Extraction, preliminary characterization and in vitro antioxidant activity of polysaccharides from Oudemansiella radicata mushroom

Oudemansiella radicata mushroom has many functions. Optimal condition of extracting its polysaccharides (ORP) with a yield of 5.85 ± 0.13% were determined by using RSM: extraction temperature 84 °C, extraction time 2.3 h and ratio of water to raw material 20.0 mL/g. ORP-1, ORP-2 and ORP-3 were further obtained by chromatography with an average molecular of 13,921 Da, 14,942 Da and 10,209 Da, respectively. ORP-1 is mainly composed of mannose, ribose, glucose, galactose and xylose in a ratio of 2.46:2.63:3.89:3.22:2.78; ORP-2 is mainly composed of ribose, glucose and xylose in a ratio of 2.63:3.38:2.65; ORP-3 is mainly composed of glucose, xylose in a ratio of 3.38: 2.65. ORP exhibits relatively strong in vitro antioxidant activity. Except crude ORP, ORP-1 has the highest DPPH and ABTS radical scavenging activity, and ORP-3 shows the strongest hydroxyl radical scavenging activity and ferrous ion chelating activity, while the three fractions have no significance in scavenging radical superoxide anion.