Structural characterization of a heteropolysaccharide isolated from hot water extract of the stems of Amaranthus tricolor Linn. (Amaranthus gangeticus L.)

摘要

A water-soluble polysaccharide(PS-I),isolated from the aqueous extract of the stems of Amaranthus tricolor Linn.(Amaranthus gangeticus L.),was found to Consist Of L-arabinose,methyl-D-galacturonate, D-galactose,and 3-O-Ac-L-rhamnose in a molar ratio of nearly 1:1:1:1.On the basis of total acid hydrolysis,methylation analysis, periodate oxidation,and NMR studies (H-1,C-13,TOCSY,DQF-COSY, NOESY, ROESY,HMQC, and HMBC),the structure of the repeating unit of the PS-I is determined as:A C D B->5)-alpha-L-Araf-(1->4)-beta-D-Galp-(1->2)-3-O-Ac-beta-L-Rhap-(1->4)-alpha-D-GalpA6Me-(1->