Isolation, Purification, Structural Characterization And Activity Study Of Polysaccharides From The Stem Of Physalis Pubescen

The crude polysaccharide from the stem of Physalis pubescens L.was extracted by refluxing with distilled water,and the protein was removed by enzymatic hydrolysis +Sevage method.The protein content was detected by Coomassie brilliant blue method,and then the crude polysaccharide was decolored.The decolored polysaccharide was separated by anion exchange chromatography column and purified by gel chromatography column to obtain four natural polysaccharides PPLS-1,PPLS-2,PPLS-3 and PPLS-4.The moleculear weights were determined as 12.6 KDa,11.6 KDa,23.4 KDa and 19.9 KDa by high performance gel permeation chromatography;the monosaccharide composition was identified by high performance liquid chromatography(HPLC).The results showed that PPLS-1 was composed of rhamnose(Rha),arabinose(Ara),mannose(Man)and galactose(Gal)with the molar ratio of 0.14: 0.46: 0.09: 0.31.PPLS-2 is composed of rhamnose(Rha),arabinose(Ara),mannose(Man)and galactose(Gal)with a molar ratio of 0.09: 0.63: 0.05: 0.23.PPLS-3 is composed of rhamnose(Rha),arabinose(Ara)and mannose(Man)with a molar ratio of 0.37: 0.46: 0.17.PPLS-4 is composed of rhamnose(Rha),arabinose(Ara)and mannose(Man)with a molar ratio of 0.26: 0.59:0.15.NMR analysis showed that the main fragment of PPLS-1 are→4)-β-D-Manp-(1→,α-D-Galp,→5)-α-L-Araf(1→ and →2)-α-D-Rhap(1→;the main fragments of PPLS-2are→2,4)-α-L-Rhap(1→,1,4-β-D-Manp,→5)-α-L-Araf(1→ and α-Galp;the main fragments of PPLS-3 are 1,4-β-D-Manp,→4,2)-D-Rha-(1→ and α-L-Araf(1→;the main fragment of PPLS-4 are →3,4)-α-l-Arap(1→ and →2)-α-D-Rhap-(1→In addition,the surface morphology and thermal stability of polysaccharides were determined by scanning electron microscopy(SEM)and thermogravimetric analysis(TGA),and the antioxidant and neuroprotective effects of four natural polysaccharides were further studied.The results of oxidative activity test showed that PPLS-1,PPLS-2,PPLS-3 and PPLS-4 had scavenging effects on DPPH and ABTS free radicals in a dosedependent manner.Through the establishment of H2O2-induced SH-SY5 Y cell model,the results showed that the four polysaccharides obtained from the stem of H2O2-induced SHSY5 Y cell model had good neuroprotective activity.In the detection of oxidative stress indicators,the content of MDA decreased gradually after adding polysaccharide sample PPLS-1 and had a dose effect.At the same time,SOD,T-AOC and GSH-Px increased.H2O2 increased the production of MDA and decreased the activity of antioxidant enzymes,while PPLS-1 effectively inhibited the formation of MDA and regulated the activity of intracellular antioxidant enzymes,indicating that PPLS-1 effectively reduced the oxidative stress induced by H2O2.The mechanism may be that PPLS-1 inhibits ROS production by maintaining endogenous antioxidant enzyme activity at normal levels.