| The dried rhizome of Polygonatum odoratum(Mill.)Druce is a famous medicinal and food resource in China.P.odoratum has heart health improvement and antihypertensive effects.Modern pharmacological investigations showed that it could improve myocardial ischemia,which was similar to the adrenocortical effect.It could also relieve the formation of atherosclerotic plaque.At present,relevant researches mainly focuse on the extraction,purification,structural characteristics,and functional activities of small molecule compounds(such as flavonoids,saponins,and sterols)from rhizome of P.odoratum.The research related to polysaccharides mainly focused on the optimization of traditional extraction techniques,identification of physicohemical properties,and the functional activities including blood glucose lowering effect,anti-diabetes,anti-tumor,anti-oxidation,etc.There are few studies on the structural characterization of polysaccharides from P.odoratum.In this paper,Polysaccharides from P.odoratum(POA)was firstly extracted from rhizome of P.odoratum(Mill.)Druce.Then,its physicochemical properties,structural characteristics,and antioxidant activity in vitro were analyzed.The main contents of this paper are as follows:1.Extraction and isolation method for polysaccharides from rhizome of P.odoratum D.(POA)was established.The crude polysaccharide was extracted by water extraction and ethanol precipitation,whose yield was 56.40%.POA was further fractionated into two fractions(POA-70S and POA-70P)by 70%ethanol precipitation.POA mainly contained neutral sugar,with a small amount of uronic acid and protein.The infrared spectra showed that POA,POA-70S,and POA-70P had typical absorption bands of β-type.SEM image showed the solid morphology of POA-70S and POA-70P was different.POA,POA-70P and POA-70S had good scavenging ability of hydroxyl radicals,while scavenging ability of DPPH free radicals was poor.2.The structure characterization of POA-70S with lower molecular weight was analyzed in this section.Specifically,the molecular weight distribution,monosaccharide composition,glycoside linkage and configuration,and morphology of POA-70S were analyzed by HPSEC,HPAEC,GC-MS and NMR,respectively.The results showed that the homogeneity of POA-70S was good,the molecular weight was 3.89x 103 Da and the hydrodynamic radius(Rh)was 1.4 um.POA-70S was mainly in smooth flake amorphous state.Fructose and a small amount of glucose,fucose,and mannose were found in POA-70S,and the corresponding mass fraction ratio was 69.05:3.85:2.65:0.30.Methylation analysis indicated that POA-70S contained Fruf(2→,D-Glcp-(1→,→6)-Fruf(2→,and→2)-Fruf-(1→ residues.NMR spectra revealed that POA-70S mainly had fructosyl residues in β-configuration and galactosyl residues in a-configuration.3.The structure characterization of POA-70P with high molecular weight was analyzed in this section using the same methods described above.POA-70P was found to have good homogeneity,and the molecular weight was 4.51×104 Da,while SEM result shows that the polymer chain of POA-70P wound into a non-uniform network and small spherical structure.Mannose and a small amount of arabinose,galactose,glucose,and galacturonic acid were found in POA-70P.The corresponding mass ratio was 36.67:1.63:8.73:5.36:0.99.The methylation results showed that the linkage in POA-70P contained D-Manp-(1→,D-Galp-(1→,→4)-Manp-(1→,→4)-Galp-(1→,→4)-Glcp-(1→,→3,6)-Galp-(1→residues. |
