Pectic substances from lucerne (Medicago sativa). Part II. Acidic oligosaccharides from partial hydrolysis of leaf and stem pectic acids

Abstract

Pectic acids isolated separately from lucerne leaves and stems have been shown to be structurally indistinguishable. Partial acid hydrolysis and/or partial acetolysis lead to the formation of oligomers of D-galacturonic acid, 2-O-(α-D-galactopyranosyluronic acid)-L-rhamnose, higher oligosaccharides containing residues of galacturonic acid and rhamnose, and small amounts of 4-O-(β-D-glucopyranosyluronic acid)-L-fucose and 6-O-(β-D-glucopyranosyluronic acid)-D-galactose. The characterisation of these and other acidic oligosaccharides formed on enzymic hydrolysis provides evidence for the role of neutral sugar residues in the structure of lucerne pectic acid.