Extraction of polysaccharides from black mulberry fruit and their effect on enhancing antioxidant activity

The optimal extraction conditions with yield of 11.86 ± 0.21% for extraction of crude polysaccharide from black mulberry fruit were obtained as extraction temperature 87 °C, extraction time 3 h and ratio of water to raw material 39 mL/g. Two purified fractions of BMP-1-1 and BMP-2-1 with average molecular weights of 615 and 405 kDa, respectively, were obtained by chromatography of DEAE-52 cellulose and Sephadex G-100. BMP-1-1 consisted of mannose, rhamnose, glucuronic acid, galactose and arabinose, BMP-2-1 consisted of rhamnose, glucuronic acid, galacturonic acid, galactose and arabinose. Crude BMP exhibited the strongest reducing power and protective effect on H2O2-induced oxidative injury in PC12 cells and the most effective scavenging activities against DPPH, ABTS and hydroxyl radical.