Characterization and antioxidant activity of a polysaccharide extracted from Sarcandra glabra

Response surface methodology (RSM) was employed to optimize the parameters for polysaccharide extracted from the aerial parts of Sarcandra glabra (SGP). The optimum conditions were predicted as follows, ratio of water to raw material at 30, extracting temperature at 85 °C, extracting duration at 3 h, and yield was estimated at 4.55%. The experimental yield of SGP under the optimum conditions was 4.49 ± 0.09%. A homogenous polysaccharide (SGP-1) was obtained by purification using DEAE-cellulose-52 and Sephacryl S-400 column chromatography. SGP-1 showed a single symmetrical peak in high performance size-exclusion chromatography (HPSEC) and the average molecular weight (Mw) was estimated to be 1.06 × 104 Da. It was composed of glucose, galactose, and mannose in a ratio of 8.38:3.13:1 determined by gas chromatography (GC). The in vitro antioxidant tests showed that SGP-1 has significant inhibition effects on hydroxyl, superoxide anion, DPPH, ABTS radicals in a dose-dependent manner. This study indicated that SGP-1 could be used as a potential natural antioxidant.