AN ACIDIC HETEROPOLYSACCHARIDE FROM THE FLOWERS OF MALVA-MAURITIANA L

An acidic heteropolysaccharide composed of L-rhamnose, D-galactose, L- arabinose, D-xylose, and uronic acids in 1.0:0.5:0.1:0.1:1.8 mole prop ortion was isolated from the flowers of M. mauritiana L. Structural st udies of the polysaccharide involved compositional and methylation ana lyses of the intact and carboxyl-reduced polymers, graded acid hydroly sis as well as H-1 and C-13 NMR spectroscopy. The results of chemical and spectroscopic analyses indicated a branched structure with the bac kbone made up of alternating sequences of 2- and 4-linked rhamnogalact uronan-type units with linear segments (DP = 2, 4, 12), segments beari ng on O-3 of D-GalA monomeric D-GlcA randomly distributed along the ch ain (DP = 7, 10, 19, 31), and segments having each D-GalA substituted (DP = 15). Moreover, the results of methylation analysis indicated tha t about 28% of L-rhamnose residues were branched through O-4.