In vitro antioxidant activity of the polysaccharide from Auricularia auricula and its structural characterisation

A new polysaccharide (AAP) was extracted from Auricularia auricula by water extraction and alcohol precipitation. The antioxidant activity in vitro showed that AAP had a good scavenging effect on ABTS free radicals. Then AAP was purified by DEAE-52 ion exchange chromatography to obtain the purified component pAAP. The structure analysis showed that the molecular weight (Mw) of pAAP was 96.768 kDa, which was composed of rhamnose (Rha), arabinose (Ara), fucose (Fuc), xylose (Xyl), mannose (Man), glucose (Glu) and galactose (Gal), with the ratio of 0.1:0.157:0.33:2.797:2.881:2.988:0.587, and contained α-pyranose configuration and β-pyranose configuration. Field emission scanning electron microscopy and atomic force microscopy revealed the special conformation of pAAP in the ring and chain shape.