Optimization of extraction technology and in vitro antioxidant activity of Dendrobium fimbriatum polysaccharides from different regions

The extraction technology of polysaccharides from Dendrobium fimbriatum by reflux method was optimized by using the response surface method. The antioxidant activities of D. fimbriatum polysaccharides collected from different regions in China were investigated using in vitro antioxidant assays: 1,1 -Diphenyl -2 -picrylhydrazyl (DPPH) radical scavenging activities. The results showed that the optimal extraction conditions were as follows: extraction temperature of 92℃, ratio of material to solvent of 1:26 and extraction time of 2.5 h. Under these conditions, the yield of D. fimbriatum polysaccharides was up to 9.18%, the best predicative extraction rate of the polysaccharides was 9.31%, and the relative error was 1.40%. The contents of polysaccharides in D. fimbriatum from Xingyi Guizhou, Luodian Guizhou, Yunnan, Guangxi were 10.34%, 8.36%, 3.35% and 6.66%, respectively. Among these 4 samples, the sample collected from Yunnan had the relatively higher antioxidant activity by using IC50 value as an index.