Optimization Of Extraction Of Polysaccharide From Dendrobium Officinale

Dendrobium officinale in China is used as a new food resource and herbal medicine.Polysaccharides are the main active component of Dendrobium officinale.In this study,Dendrobium officinale polysaccharide（DOP）is extracted by standard water extraction and alcohol precipitation method,and the quantity of polysaccharide is determined by phenol-sulfuric acid method.While the Antioxidant activity of polysaccharide is evaluated under seedbed and stump cultivation mode.The effects of extraction temperature,solid liquid ratio and extraction time and the extraction rate of polysaccharides from Dendrobium officinale is also evaluated.The extraction of polysaccharides from Dendrobium officinale was optimized using a single factor experiment,Box-Behnken central composite design,and Response Surface Methodology（RSM）.The following are the optimum polysaccharide extraction conditions from Dendrobium officinale,as found by a quadratic polynomial regression equation prediction model: 80℃,1: 35,and 2 hours were the temperature,solid-liquid ratio,and extraction times,respectively.The FRAP method was used to determine the antioxidant activity of DOP as well as their ability to scavenge DPPH,ABTS,and Hydroxyl radicals.The results demonstrated that the FRAP value can explain the iron ion reducing ability,and that the higher the value,the stronger the iron ion reducing capacity.The antioxidant activity of DOP cultivated on the stump was higher than that of seedbed growing method,according to the results of scavenging ability of three types of free radicals.