CONSTITUTION OF AN ARABINOGALACTAN FROM MAPLE SAP

Abstract

An arabinogalactan [Formula: see text] has been isolated from maple sap in yields varying between 7.5 and 17.0 mg per 100 ml of sap. The polysaccharide was electrophoretically homogeneous and contained D-galactose, L-arabinose, and rhamnose in a molar ratio of 51:44:5. Methylation and hydrolysis of the polysaccharide yielded the following O-methyl ethers which were analyzed by gas–liquid partition chromatography: 2,3,5-tri-O-methyl-L-arabinose (4 moles); 2,5-di-O-methyl-L-arabinose (2 moles); 2,4-di-O-methyl-D-galactose (4 moles); 2,4,6-tri-O-methyl-D-galactose (7 moles); 2,3,4-tri-O-methyl-L-rhamnose (1 mole). A possible structure for the polysaccharide is proposed and discussed in relation to other arabinogalactans.