Effect Of Purification And Separation On Bioactivity Of Polysaccharide From Dendrobium Officinale

Dendrobium officinale Kimura et Migo is a rare medicinal material in China.Dendrobium officinale polysaccharide is the main active substance of Dendrobium officinale.It is used as the standard to measure the quality of Dendrobium officinale in Chinese Pharmacopoeia（2015 edition）.In this study,Dendrobium officinale polysaccharides were purified and separated,in vitro activity determination and animal experiments were used to evaluate the effect of purification and separation on the biological activity of Dendrobium officinale polysaccharides,and the research and development of Dendrobium officinale effervescent tablets were carried out.The main contents and conclusions of this paper are as follows:（1）Dendrobium officinale water extract was used to prepare Dendrobium officinale water soluble substance（ODOP）and Dendrobium officinale polysaccharide（CDOP）.The purity of purified polysaccharide（DOP）from Dendrobium officinale was 89.06%after salting out protein,decolorizing with sodium hypochlorite,freezing and thawing repeatedly.Molish reaction,ultraviolet-visible spectroscopy and infrared spectroscopy showed that the purification effect was good,and the purification process had little influence on the main structure of polysaccharide.（2）The effect of purification degree on polysaccharide activity of Dendrobium officinale was evaluated in vitro.The results showed that CDOP with different purification degree had DPPH free radical scavenging capacity(IC₅₀ value was 0.58 mg/mL⁰.78 mg/mL),α-glucosidase activity inhibition ability(IC₅₀ value was 3.00 mg/mL³.80 mg/mL),tryptolipase activity(IC₅₀ value was 1.80 mg/mL².50 mg/mL)and cholesterol lipase activity inhibition ability(IC₅₀ value was 2.00 mg/mL².50 mg/mL),and the higher the purity,the better the effect.（3）DOP was separated by diethylaminoethyl cellulose column chromatography.The neutral polysaccharides（77.35%by distilled water elution）and acid polysaccharides（19.44%by NaCl aqueous solution elution）of Dendrobium officinale were collected.The separation effect was evaluated by Fourier transform infrared spectroscopy and the structure type of polysaccharides of DOP was studied.At the same time,the relative molecular mass elution volume relationship of standard polysaccharide was obtained by dextran gel G-200 elution,which was Y=0.0695X+45.243.The neutral polysaccharide of Dendrobium officinale was separated by the same method.The polysaccharide fragments 1（DOP-1,197.9 kDa⁴71.3kDa）and polysaccharide fragments 2（DOP-2,10.9 kDa¹97.9 kDa）of Dendrobium officinale were obtained by elution with different volume eluents.（4）Established a hyperlipidemia mouse model,simvastatin,ODOP,CDOP,DOP,DOP-1（Dendrobium officinale neutral polysaccharide fraction 1,197.9 kDa⁴71.3 kDa）and DOP-2（Dendrobium officinale neutral polysaccharide fraction 2,10.9 kDa¹97.9 kDa）were used as drug delivery materials respectively for evaluating the hypolipidemic effect of polysaccharides from Dendrobium officinale in different purity and relative molecular weight on hyperlipidemia mice.The results showed that polysaccharides from Dendrobium officinale had a good hypolipidemic effect,and purification could improve its hypolipidemic ability in mice with high blood lipid.The polysaccharides with higher molecular weight had better hypolipidemic effect.Polysaccharides from Dendrobium officinale in different purity and relative molecular weight could significantly inhibit the increase of body weight,BMI and Lee’s index induced by high-fat diet in mice（P<0.05）,and significantly reduce the contents of total cholesterol（TC）,triglyceride（TG）and low-density lipoprotein cholesterol（LDL-C）in serum of mice with high-fat diet（P<0.05）,at the same time the content of high-density lipoprotein cholesterol（HDL-C）increased significantly（P<0.05）,of which DOP had the most significant effect.Dendrobium officinale polysaccharides can also y reduce the activities of alanine aminotransferase（ALT）and aspartate aminotransferase（AST）in the liver of hyperlipidemia mice（P<0.05）,and alleviate the lipid-induced liver lipidization in mice.