Structural features of water-soluble novel polysaccharide components from the leaves of Tridax procumbens Linn.

Abstract

Two water-soluble polysaccharide fractions, WSTP-IA and WSTP-IB were purified from the leaves of Tridax procumbens Linn. with graded ethanol precipitation followed by mild delignification and size-exclusion chromatography. WSTP-IA contained l-Ara f and d-Gal p in ∼1:3 molar proportions, and WSTP-IB contained only d-Gal p as the major sugar component. The results of methylation linkage analysis, and 1H and 13C NMR studies on the native and modified polysaccharides, indicated that WSTP-IA is an l- arabino- d-galactan with a β-(1 → 6)- d-galactan main chain in which at least one in every two d-Gal p residues carries single residues of either l-Ara f (α-/β-) or β- d-Gal p end-group as substituents at O-3. WSTP-IB is a linear β-(1 → 6)- d-galactan. This is the first report of polysaccharides containing a β-1(1 → 6)- d-galactan main chain isolated from plant sources.