Purification And Structural Analysis Of Polysaccharide From Rhizoma Anemarrhenae

Anemarrhena asphodeloides Bge.belongs to Liliaceae.It is a traditional Chinese medicine and has many fuctions.Polysaccharide is one of the major active components in Anemarrhena asphodeloides Bge.,which has hypoglycemic,anti-inflammatory,and immunoregulatory effects.However,the structure characteristics of polysaccharide from Anemarrhena asphodeloides Bge.are rarely reported.To better understand the structure-activity relationship of polysaccharide in Anemarrhena asphodeloides Bge,the polysaccharide was extracted and structurally analyzed here.Polysaccharide(WABP)was extracted from Anemarrhena asphodeloides Bge.by using hot water and precipitated by ethanol,with the yield of 8.2%.WABP contained 55.2% total carbohydrates,19.2% uronic acid,and 0.8% protein.According to complete acid hydrolysis and HPLC analysis,the main monosaccharide in WABP were determined as Man: GalA: Glc: Ara: Gal = 32.3: 23.6: 14.1: 14.1: 11.2.WABP was fractionated by DEAE-cellulose.A neutral fraction(WABP-N)was obtained by elution with distilled water,with the yield of 54.3%,and an acid fraction(WABP-A)was eluted by 0.5 M NaCl solution,with the yield of 21.7%.WABP-A was further purified by DEAE-cellulose.Four fractions WABP-AH,WABP-A2,WABP-A3 and WABP-A5 were obtained by elution with different salt solutions.WABP-A2(yield 56.6%)and WABP-A3(yield 30.3%)were major fractions.WABP-A2 was further purified by using Sepharose CL-6B column,and three homogeneous fractions WABP-A2 a,WABP-A2 b,WABP-A2 c were obtained.WABP-A3 was purified by using Sepharose CL-6B column,and two homogeneous fractions WABP-A3 a and WABP-A3 b were obtained.The structures of WABP-A2 a,WABP-A2 b and WABP-A3 a were analyzed by monosaccharide composition analysis,infrared spectroscopy,methylation analysis and nuclear magnetic resonance analysis.According to these results,it is speculated that the three fractions were RGI type pectin,containg ?-1,4-GalpA and ?-1,2-Rha in the main chain.The side chains contained highly branched arabinan,and type I arabinogalactan(AG I).Type II arabinogalactan(AG II)was also detected in WABP-A2 b.FT-IR and NMR results indicated that WABP-A2 c and WABP-A3 b were mainly composed of HG domains,and some GalA residues were paitially methyl esterified and acetyl esterified.Enzymatic hydrolysis indicated that WABP-A2 c and WABP-A3 b were not only composed of HG domains,but also small amounts of RG-I and RGII domains,which were covalently linked.In this thesis,the structures of polysaccharides from Anemarrhena asphodeloides Bge.were studied in detail.These results provided a structural basis for the pharmacological activity and structure-activity study of these polysaccharides.