Structural Characterization Of A Polysaccharide Promoting GLP-1 Secretion From Polygonatum Cyrtonema Hua

Through ethanol extraction,hot water extraction and ethanol precipitation,we obtained six components including ethanol extracts,water extracts,ethanol extracts from water extraction,ethanol precipitates,total polsaccharides and crude polysaccharides(PCP)from Polygonatum cyrtonema Hua.PCP was then fractionated by DE52-preswelling ion exchange cellulose to get a water-soluble polysaccharide PCP1(64.63%)and five acidic polysaccharides.They are PCP-S1(3.37%),PCP-S2(2.38%),PCP-S3(2.04%),PCP-S4(0.82%),PCP-S5(0.74%),respectively.Further,Sephadex G-100 filtration chromatography of PCP1 gave a homogeneous polysaccharide PCP11.Determination of GLP-1 secreted from intestinal endocrine L-cells in vitro indicated PCP was the main effective component from Polygonatum cyrtonema Hua.Water-soluble polysaccharide PCP11 was the main active fraction in crude polysaccharide PCP,which can significantly promote GLP-1 secretion by intestinal endocrine L-cells in vitro.The physicochemical properties and structure indentification of PCP11 were analyzed.The results showed that PCP11 was a homogeneous polysaccharide with a relative molecular weight of 8547 Da.By ammonium molybdate colorimetric method determination and GC analysis,PCP11 was found to be mainly composed of fructose as well as a small amount of glucose.Methylation reaction and NMR analysis showed that the fructoses in PCP11 had four linkage types,including β-(2→1,6)-D-Fruf,β-(2→6)-D-Fruf,β-(2→1)-D-Fruf and β-(2→)-D-Fruf,and glucose was linked in the form of α-(1→)-D-Glcp.