Isolation,Purification And Structural Analysis Of Polysaccharides From The Fruits Of Physalis Alkekengi L.

Physalis alkekengi L.var.franchetii(P.alkekengi)is a Physalis plant,also known as Hong Gu Niang in Chinese,mainly grows in Heilongjiang,Jilin and Liaoning provinces.It has a long history of use in folk,and can be used as medicine and raw food.Studies have shown that the polysaccharides from the fruits of the P.alkekengi have antibacterial,anti-inflammatory,antitumor and alleviating symptoms of diabetes.The detailed analysis of the polysaccharide composition of the polysaccharides from the fruits of P.alkekengi is unclear.In this paper,the polysaccharides from the fruits of P.alkekengi were separated and purified systematically,and the structure of main polysaccharides from the fruits of P.alkekengi was analyzed,which lay the foundation of the structure-activity relationship for the polysaccharides from the fruits of P.alkekengi in the future work.The results about this research are listed as following.Using commercially available P.alkekengi fruits as raw materials,the fruits were crushed and extracted with boiling water for three times,and the final concentration of 75% ethanol was used to precipitate the polysaccharides,and PPS was obtained after drying.The sugar content of PPS is 39.95%,the protein content is 5.59%,and the uronic acid content is 36.98%.PPSB-1,PPSB-2 and PPSB-3 were obtained by using 30%,50% and 70% final concentration ethanol after removing insoluble materials from PPS by repeated freezing-thawing,and the yield is at least in the order of PPSB-1,PPSB-3 and PPSB-2.PPSB-1,PPSB-2 and PPSB-3 were systematically separated and purified by DEAE-cellulose column and Sepharose CL-6B gel column.A total of 10 polysaccharide fractions were isolated,which were PPSB-1N1,PPSB-1Ab1,PPSB-1Ab2;PPSB-2N1,PPSB-2Ab1;PPSB-3N1,PPSB-3N2,PPSB-3Aa1,PPSB-3Ab1 and PPSB-3Ab2.Among them,PPSB-3 has more acidic polysaccharide fractions.Due to the low yields of PPSB-1Ab1,PPSB-2N1 and PPSB-3N2,only the other seven components were analyzed by molecular weight homogeneity.The results showed that the molecular weight of neutral polysaccharides is lower than that of acidic polysaccharides.The molecular weights of neutral polysaccharides PPSB-1N1 and PPSB-3N1 are less than 10.00 kDa,and the molecular weights of acidic polysaccharides PPSB-1Ab2,PPSB-2Ab1,PPSB-3Aa1,PPSB-3Ab1 and PPSB-3Ab2 are 16.00~830.00 kDa.Among the components,the recovery rate of acidic polysaccharides is higher than that of neutral polysaccharides,and it is the main component.The composition and proportion of monosaccharides in polysaccharides of P.alkekengi were detected by high performance liquid chromatography.The results showed that the neutral polysaccharides PPSB-1N1 and PPSB-3N1 are mainly composed of Gal,Xyl and Ara,and Gal is the main component,up to 70%.The acidic polysaccharides from the fruit of P.alkekengi are mainly composed of GalA,Gal,Ara or Xyl.The proportion of different acidic polysaccharides is different.Among them,PPSB-1Ab2 which was separated and purified from PPSB-1 has the highest GalA content(57.33%),the GalA content of PPSB-2Ab1 which was isolated and purified from PPSB-2 is 34.85%,the GalA contents of PPSB-3Aa1,PPSB-3Ab1 and PPSB-3Ab2 which were separated and purified from PPSB-3 are 14.51%,29.05%,38.53%,showing the content of GalA varies greatly.PPSB-1Ab2,PPSB-2Ab1 and PPSB-3N1 were methylated and analyzed by GC-MS,and the main glycosidic bond types were analyzed.The experimental results showed that GalA in acidic polysaccharides PPSB-1Ab2 and PPSB-2Ab1 is in the form of 1,4-GalAp,with branches at the O-3 and Gal terminal.The difference is that Gal in PPSB-1Ab2 is in the form of 1,6-Galp and has branches at the O-4,while Xyl is in the form of 1,4-Xylp and has branches at the O-2 and Xyl terminal.Gal in PPSB-2Ab1 is in the form of 1,4-Galp and has branches at O-3 and O-6.Xyl is in the form of 1,2-Xylp and has branches at O-4.The neutral polysaccharide PPSB-3N1 is composed of 1,4-Galp as the main structure and has branches at the O-6,meanwhile Ara is in the form of 1,5-Araf and has branches at the O-3;it is also found PPSB-3N1 is terminated with Gal,Ara and Xyl.In the future,its biological activity will be further studied to explore its structure-activity relationship.