Purification And Structural Analysis Of Polysaccharides Isolated From Portulaca Oleracea L.

Portulaca oleracea L,also known as Purslane,is a plant of dual-use mainly for medicine and food.The whole plant is medicinal and grows in the wild,especially in tropical and oriental countries.P.oleracea contains various active ingredients such as polysaccharides,ketones,amino acids and the like.As one of its main components,polysaccharide has various activities such as anti-inflammatory,anti-tumor and blood sugar lowering.Previous studies on polysaccharides from P.oleracea focused on water extraction and the aqueous extracts.However,the extraction of polysaccharides from the alkali solution has not been reported yet.In this paper,the separation and purification of polysaccharides from P.oleracea.which extracted from aqueous solution and alkaline solution were established respectively.The method of separation and purification of polysaccharides from P.oleracea.was also established.The structure of some polysaccharides was analyzed to lay the foundation for further studies.In this thesis,the dried purslane was used as the experimental material.P.oleracea.POPW was polysaccharide extracted from P.oleracea by boiling water,which the yield was 5.0%.The polysaccharide content of POPW was 40.6 % and the protein content was 5.5%.POPA was polysaccharide extracted from the purslane residue by alkaline which was from purslane after POPW was extracted.The yield of POPA was 20.0%.POPA has a polysaccharide content of 48.7% and a protein content of 21.0%.The results indicated that the polysaccharide content of POPA in purslane is higher than that of POPW.After repeated freezing and thawing and grading alcohol precipitation,POPW and POPA were further separated and purified by DEAE-Cellulose ion exchange chromatography and Sepharose CL-6B gel chromatography to obtain different polysaccharide components.The separation and purification results showed that two neutral polysaccharide(POPW50-N and POPW75-N)and three kinds of acidic polysaccharide(POPW30-A,POPW50-A and POPW75-A)were isolated from POPW.POPW30-Ab(30% ethanol precipitated)obtained by gel chromatography is the main component of POPW,the yield is 18.6%,the molecular weight is 41.2 KDa,and the uronic acid content is about 90%.After separation and purification of POPA,two kinds of polysaccharide,which are POPA-N-a(52.6 KDa)and POPA-N-b(24.8 KDa),and five kinds of acidic polysaccharide,were obtained.(POPA-A-1a(185.2 KDa),POPA-A-1b(68.7 KDa);POPA-A-2a(134.3 KDa)、 POPA-A-2b(49.6 KDa);POPA-A-3b(155.5 KDa).)Among them,POPA-A-1a and POPA-A-1b are the main components.Also,this paper analyzed the structure of POPW30-A-b polysaccharide and POPA-N-a by high performance liquid chromatography,methylation analysis,infrared spectroscopy and nuclear magnetic resonance analysis.The results showed that POPW30-A-b is α-1,4-GalAp glycan,which is an unesterified pectin polysaccharide HG domain;POPA-N-a is an arabinogalactan with 1,4-Gal as the main chain,possibly the side chain structure has a branch on Gal’s O-6 with Gal and Ara termination.