Extraction, Separation And Anti-tumor Activity Of Polysaccharides In Dendrobium Huoshanense

Dendrobium huoshanense is the earliest recorded Medicinal plant in China, and is famous for its medicinal value. Polysaccharide is one of the most important active ingredients in it. In this paper, the process of extracting polysaccharides form Dendrobium huoshanense is optimized, and several polysaccharide components are separated. Afterwards, anti-tumor activity of polysaccharides is researched in human gastric cancer cell SGC-7901. It primely explored the effect of polysaccharide on the tumor-associated genes, p53 and c-myc.With single factor experimental design, Box-Behnken experimental design and response surface analysis, the mathematical model of Dendrobium huoshanense polysaccharide extraction rate was established based on data of extraction temperature, pH and extraction time. Equation of the model is Y=0.175767+0.023363X₁+0.013662X₂-0.032858X₁²+0.019X₁X₂-0.026308X₂². The optimum conditions were temperature of 69.4°C, time of 1.57h, pH of 5.9, ratio of material to water of 1:20 and 2 times extraction. Under these conditions, the model value was coincident with the actual value by 98.4%.Comparison of two deproteinization methods and five decolorization methods suggest, although deproteinization rate of Sevag method was less than that of TCA method, the polysaccharide content was maintained better. Sevag method was a better deproteinization method. Decolorization with DEAE-cellulose had a higher decolorization rate, less loss rate. Although DEAE-cellulose is expensive, its recycling is convenient. DEAE-cellulose is a better mateiral to decolorization.Dendrobium huoshanense polysaccharide extracted with hot water was separated by DEAE-cellulose ion exchange chromatography. Polysaccharide HDP-1,HDP-2,HDP-3,HDP,HDP-5,HDP-6 were gained. The polysaccharide HDP-2 with maximum anti-tumor rate was continuously separated by Sephacryl-200HR chromatography. Two polysaccharide components HDP-2-B and HDP-2-A were gained, which were with non-protein under UV scanning.The quantitative RT-PCR analysis showed that polysaccharide component HDP-2 significantly reduced the expression of tumor gene c-myc to 42.34%, and substantially increase the expression of wild-type p53 tumor suppressor gene to 204.2% in gastric cancer cells SGC-7901. Further work on the anti-tumor mechanism of Dendrobium huoshanense polysaccharides is still carried on.