Structural Characterization And ACE Inhibitory Activity Of Polysaccharide From Gastrodia Elata Blume

Gastrodia elata Blume(GE)belongs to Orehidaceae family and is one of the most valuable Chinese herbal medicine.Its rhizome is used to treat dizziness,limb numbness,pediatric disturbance and high blood pressure.The early research on GE was mainly focused on gastrodin,but not much of the research on the polysaccharides.Therefore,the purpose of this paper was to study the isolation,purification,structural characterization and physicochemical properties of GE,and its ACE inhibitory activity was evaluated.The main results were as follows:On the basis of one-factor tests,the method of response surface analysis was carried out to determine the optimal condition of the extraction.The optimum extraction parameters of PGE were obtained:60?for extraction temperature,2 h of extraction time,1:50(g/mL)for the ratio of solid to liquid and the amount of polysaccharide extracted from Gastrodia elata Blume was about 15.81%.The one homogeneous component polysaccharide(PGE)extracted from GE by hot water,enzyme-sevag.deprotein and purified by Sephadex G-200 and ultra-fltration.The structural characterization of PGE was analyzed by HPLC,FT-IR,NMR spectroscopy,DSC,TGA,specific.rotation determination,periodate oxidation-smith degradation,methylation analysis and Congo red test.Identification of qualitative chemical reaction showed PGE was pure neutral polysaccharide,no nucleic acid,protein and starch.The results revealed that PGE was composed by glucose,with an average molecular weight of 1.54x103 kDa.The backbone of PGE was composed of a-(1?4)-linked-d-glucopyranosyl,while the branches comprised of 1?3-linked-d-glucopyranosyl,1?4,6-linked-d-glucopyranosyl.The specific optical rotation of PGE was +155° and it was absent of triple helix structure,the results of DSC and TGA revealed that PGE had good thermal stability as well.In the activity inhibition of ACE research test,Captopril as a positive control,the ACE inhibition activities of PGE was investigated in this paper.The results of the study revealed that the ACE activity-inhibitory effects of PGE were proportional to the concentrations used.PGE was efficient to inhibit ACE and the ICso value was of 0.66 mg/mL for PGE.