Preliminary Study On Structure And Anti-oxidation Of The Polysaccharide From Dendrobium Officinale

Dendrobium is one of the expensive medicines in our country, having a very high medicinal value. Dendrobium polysaccharides are the most important medicinal ingredients. Studying the structure and function of Dendrobium polysaccharide will play an important role in health care. In this paper, Dendrobium was selected as materials, and Dendrobium polysaccharides extraction methods were optimized. In addition, the polysaccharides DOP with unique component was collected through separation and purification, moreover, preliminary study of the structure and antioxidant activity of the polysaccharides DOP was carried out.Trials were conducted by the means of response surface method in this research. Extraction temperature, extraction time, extraction times and solid-liquid ratio were selected to be integrated into four independent single factor tests respectively, then three influencing factors in extraction process(extraction temperature, extraction time, solid-liquid ratio) were confirmed. After that, Box-Behnken method was used to analysis the three factors in order to find the best extraction conditions. The results showed that the best extraction condition was solid-liquid ratio1:43, extracting time2h, and extraction temperature80℃, respectively, as the extraction times were set to2times. Under these conditions, the average extraction rate of polysaccharide was18.35%. Compared to the theoretical value, the relative error was0.9%. It suggests that the conditions optimized have practical value.Polysaccharides of Dendrobium was isolated by DEAE-52cellulose column and four kinds of polysaccharide (DO-1, DO-2, DO-3, DO-4) were got, then the component DO-1was purified by Sephadex G-200column, polysaccharide DOP was got. Using the method of pre-column derivatization with1-phenyl-3-methyl-5-pyrazolone(PMP) for HPLC analysis, Infrared spectroscopy analysis of functional groups, polysaccharides viscosity-average molecular weight were measured, periodate oxidation Determination of polysaccharide molecules keys use viscosity method.and the results showed that, polysaccharides DOP is composed of D-mannose, L (+)-rhamnose and D-glucose, and the external standard informed that D-mannose:L(+)-rhamnose:D-glucose=1.936:0.856:0.691. By infrared spectra analysis, it confirmed that the the polysaccharide DOP had the characteristics of carbohydrate, and was a neutral polysaccharide. The molecular weight of polysaccharide DOP was48.82×10. By the reaction of periodate with polysaccharides, it confirmed that in polysaccharides DOP,1â†'6bond to the non-reducing terminal residue of group (1â†') accounted for4.0%, can be periodate oxidized to formic acid is not generated or a1â†'2bond linked residues accounted for52.1%, not44.9%periodate oxidation of1â†'3linkage residues.DPPH radical scavenging, hydroxyl radical scavenging and the β-carotene-antioxidant effects of linoleic acid system were determined. Result showed that the polysaccharide DOP on DPPH radical scavenging rate reached more than50%, the hydroxyl radical scavenging rate reached58.24%, the P-carotene-antioxidant capacity of linoleic acid is51.05%, the antioxidant capacity of the three measurements, more than50%of the antioxidant capacity, indicating Dendrobium polysaccharides have strong physiological activity.