Optimized Extraction and Compositional Analysis of Polysaccharides from Dried Stems of Dendrobium officinale

Response surface methodology was utilized to optimize the extraction process of polysaccharides from dried stems of Dendrobium off icinale(DOP).The physiochemical properties of DOP obtained by the optimized process were analyzed.The optimal extraction conditions were found to be an extraction duration of 2 h at 90 ℃ with a water/material ratio of 30:1(mL/g).The yield of polysaccharides under the optimized conditions was 30.56%.In the resulting extract,78.21% of neutral polysaccharide,18.64% of starch,5.8% of protein and 1.28% of ash were contained,with mannose and glucose being the major monosaccharides at a molar ratio of 5.2:1.DOP was rich in Ca(1.07%),Mg(0.11%),Fe(0.0012%) and Zn(0.0039%).HPGPC analysis demonstrated that the polysaccharide was homogeneous with a single peak.This polysaccharide-rich extract may be useful for future studies on its activity and structure-activity relationship.