Extraction, purification, characterization and antioxidant activities of polysaccharides from Ramaria botrytis (Pers.) Ricken

BACKGROUND Ramaria botrytis (Pers.) Ricken, a member of the family Clavariaceae, has been widely prescribed for anti-aging and improving immunity. To extract and purify the polysaccharides, the main constituent of the fruiting-body, from R. botrytis and explore antioxidant activities was great significant. RESULTS Ramaria botrytis polysaccharides (RBP) was extracted with water at 88.47 °C for 1.42 h with a solution to sample ratio of 10.94 mL g-1 employing response surface methodology. Four purified fractions, RBP-1, RBP-2, RBP-3, and RBP-4, were obtained from column chromatography of DEAE-52 and Sephadex G-100. Among these four purified fractions, RBP-1, RBP-2, RBP-4 were mainly composed of glucose, while RBP-3 contained 41.36% mannose and 28.96% glucose. The molecular weights of RBP-1, RBP-2, RBP-3 and RBP-4 were 6.48, 36.12, 96.72 and 8.34 kDa, respectively. These four fractions are also tested for antioxidant activities in vitro, RBP-4 exhibited strong assay of reducing power and high scavenging activity on DPPH radical, while RBP-3 showed the stronger ability of hydroxyl radical scavenging activity. CONCLUSIONS Response surface methodology was successfully applied to optimize the ultrasonic extraction of polysaccharides from R. botrytis. RBP is an efficient natural antioxidant.