Extraction,structural characterization and antioxidant activity of polysaccharide from Den-drobium officinale in Yandang Mountain,China
In the present study,the fresh stem of Dendrobium officinale in Yandang Mountain was selected as the test object,the liquid-to-material ratio,extraction temperature,extration time and extraction times were selected as the key factors,as well as the yield of polysaccharide being response value,to optime the extraction process of polysac-charide from D.officinale in Yandang Mountain.The structure of the extracted polyssacharide was preliminarily ex-plored by Fourier infrared spectroscopy and high performance liquid chromatography(HPLC).Besides,the in vitro activity of polysaccharides to scavenge free radicals was examined.The results showed that the optimal process condi-tions for the extraction of polysaccharide were liquid-to-material ratio of 55∶1(mL·g-1),extraction temperature of 80℃,extraction time of 130 min,and extraction times of 2 times.The actual polysaccharide yield under these con-ditions was 31.02％.By infrared spectroscopic analysis,it was shown that the polysaccharide contained both α-type and β-type glycosidic bonds,and the extracted polysaccharide was composed of mannose,glucuronic acid,galactu-ronic acid,glucose and xylose,and the amount of substance ratio of the above monosaccharides was 1.57∶0.49∶0.99∶2.08∶1.00.In vitro,the extracted polysaccharide could scavenge 1,1-diphenyl-2-trinitrophenylhydrazine(DP-PH)radicals,2,2'-azino-bis-3-ethylbenzothiazoline-6-sulfonic acid(ABTS)radicals,hydroxyl free radicals and su-peroxide anion,and the determined half maximal inhibitory concentrations(IC50)were 2.46,4.47,5.60,2.66 mg·mL-1,respectively,indicating that the extracted polysaccharide had antioxidant activity.
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