CHARACTERIZATION OF THREE HEMICELLULOSES FROM THE WOOD OF AMABILIS FIR (ABIES AMABILIS)

Authors:
  • ESE. C. A. Schwarz
    E. C. A. Schwarz
  • TTT. E. Timell
    T. E. Timell

Abstract
An arabino-4-O-methylglucuronoxylan (10:14:76), a water-soluble galactoglucomannan (1:1:3), and an alkali-soluble galactoglucomannan (0.1:1:3) have been isolated in yields of 7, 4, and 8% from the wood of amabilis fir (Abies amabilis). The structure of the polysaccharides was established by methylation and periodate oxidation techniques. The xylan ([ ]) contained side chains of (1 → 2)-linked 4-O-methyl-α-D-glucuronic acid and (1 → 3)-linked α-L-arabinofuranose residues, both attached directly to a linear framework of (1 → 4)-linked β-D-xylose residues. The galactoglucomannans ([ ] 76 and 95) contained (1 → 6)-linked α-D-galactopyranosyl residues attached directly to a backbone of (1 → 4)-linked β-D-mannose and β-D-glucose residues. Partial hydrolysis of the two hexosans yielded 10 and 13 oligosaccharides, respectively, containing (1 → 4)-β-D-mannose, (1 → 4)-β-D-glucose, and (1 → 6)-α-D-galactopyranose residues. The molecular rotations of a series of mannooligosaccharides corresponded to a value of −54° for the specific rotation of an infinitely long mannan. It is concluded that the main hemicelluloses in amabilis fir wood are the same as those occurring in the wood of gymnosperms from other genera. The same three hemicelluloses are also present in the bark of this species.

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