Galactomannan from the seed of Lotus pedunculatus

Abstract

A galactomannan composed of D-galactose (49%) and D-mannose (51%) was isolated in 2.2 % yield from the seeds of Lotus pedunculatus by water extraction. On periodate oxidation it consumed 1.5 moles of oxidant per hexose unit, releasing 0.53 mole of formic acid. Hydrolysis of the methylated polysaccharide gave, as the major products, 2,3,4,6-tetra-O-methyl-D-galactose (6 parts), 2,3-di-O-methyl-D-mannose (6.25 parts), and 2,3,6-tri-O-methyl-D-mannose (1 part). It is concluded that the polysaccharide contains essentially linear chains of l → 4-linked P-D-mannopyranose units with side-chains of a-D-galactopyranose units attached to C6 of approximately six out of every seven D-mannopyranose units. The galactomannan is more highly branched than similar galactomannans isolated from the seeds of other legumes.