Purification, chemical characterization and antioxidant activities of a novel polysaccharide from Auricularia polytricha

A novel water-soluble polysaccharide coded APP3a was isolated and purified from Auricularia polytricha by DEAE-52 cellulose and Sephadex G-200 column chromatography. Chemical characterization of APP3a was investigated based on analysis of high performance liquid chromatography (HPLC), gas chromatography (GC), fourier transform infrared spectroscopy (FT-IR) and thermal gravimetric analysis (TGA). Antioxidant activities of APP3a were investigated on the basis of superoxide anion,1,1-diphenyl-2-picrylhydrazyl (DPPH), hydroxyl radical scavenging activity and reducing power. The results showed that APP3a consisted of arabinose, mannose, glucose and galactose in a molar ratio of 1:133:1.06:1.23 with an average molecular weight of 21,242 Da. Thermal gravimetric analysis showed that APP3a was relatively stable below 250 degrees C. APP3a showed the stronger reducing power and stronger scavenging activity against hydroxyl radicals, superoxide radicals and DPPH radicals in a concentration-dependent manner. These findings suggested that the polysaccharide APP3a could be served as a novel antioxidant in functional food. (C) 2018 Published by Elsevier B.V.