Extraction optimization, characterization and bioactivity of crude polysaccharides from Herba Moslae

Response surface methodology (RSM), based on a Box–Behnken design (BBD), was used to optimize the extraction conditions of crude polysaccharides from Herba Moslae. Three independent variables, extraction temperature, extraction time and water to solid ratio were investigated. Based on the RSM analysis, the optimal extraction conditions were determined to be at a temperature 86.9 °C, time 4.1 h and water to solid ratio 17.7:1 (mL/g). The crude polysaccharides produced under these optimal conditions contained 37.84% neutral carbohydrates, 6.14% proteins, 5.18% uronic acids, 8.1% moisture and 4.6% ash. The result of monosaccharide composition by gas chromatography (GC) showed that the crude polysaccharides consisted of eight kinds of monosaccharides: rhamnose, ribose, fucose, arabinose, xylose, mannose, glucose and galactose, with the molecular ratio of 3.72:2.45:0.92:6.00:2.76:5.09:13.53:9.58. Results of pinocytic activity and nitric oxide assays of mouse peritoneal macrophage suggested that the crude polysaccharides had potential immunomodulatory properties.