CONSTITUTION OF A GLUCOMANNAN FROM THE WOOD OF EASTERN WHITE PINE (PINUS STROBUS L.)

Abstract

Glucomannans have been isolated from the wood of eastern white pine (Pinusstrobus L.) by two different methods, the ratios of mannose to glucose being 3.8:1 and 2.7:1, respectively. The yields, based on the mannose content of the wood, were 70 and 50%. Partial acid hydrolysis gave 4-O-β-D-mannopyranosyl-D-mannose, 4-O-β-D-mannopyranosyl-D-glucose, 4-O-β-D-glucopyranosyl-D-mannose, 4-O-β-D-glucopyranosyl-D-glucose, O-β-D-mannopyranosyl-(1 → 4)-O-β-D-mannopyranosyl-(l → 4)-D-mannose, and O-β-D-mannopyranosyl-(l → 4)-O-β-D-mannopyranosyl-(l → 4)-O-β-D-mannopyranosyl-(l → 4)-D-mannose. The fully methylated polysaccharide on hydrolysis gave a mixture of di-O-methylhexoses, 2,3,6-tri-O-methyl-D-mannose, 2,3,6-tri-O-methyl-D-glucose, and 2,3,4,6-tetra-O-methylhexose (mostly mannose) in a mole ratio of 4:61:21:1. The number-average degrees of polymerization of the methylated and the nitrated glucomannans were 96 and 93. On the basis of this and other evidence it is concluded that the glucomannan contains at least 90 mannose and glucose residues linked together by (1 → 4)-β-glycosidic bonds to linear macromolecules. The nature and relative composition of the oligosaccharides obtained on partial hydrolysis indicate that very few of the glucose residues are contiguous. The glucomannan is compared with similar polysaccharides from the wood of other gymnosperms.