Planta Med 2010; 76 - P230
DOI: 10.1055/s-0030-1264528

Characterisation of arabinogalactan from larch

J Utermoehlen 1, E Goellner 1, R Kramer 2, B Classen 1
  • 1Pharmaceutical Institute, University of Kiel, Pharmaceutical Biology, Gutenbergstr. 76, 24118 Kiel, Germany
  • 2Lonza Ltd, Lonza Chemicals Research & Development, Rottenstr. 6, 3930 Visp, Switzerland

Larch arabinogalactan (LAG) is a polysaccharide obtained from the wood of larch tree (Larix species). LAG is approved by the U.S. Food and Drug Administration (FDA) as a source of dietary fiber [1], but also has potential therapeutic benefits as an immune stimulating agent [2]. Our research tends to structural analysis of LAG as the main component of FiberAid™. Elementary analysis of LAG has shown that carbon and hydrogen atoms can be found in a 1: 2 molar ratio. No nitrogen or sulphur atoms could be detected, which indicates that LAG is not attached to a protein moiety. Quantification of neutral sugars by acetylation pointed out a 1: 5.8 ratio of arabinose (Ara) to galactose (Gal) as main monosaccharides. Determination of uronic acids by specific reduction with deuterium-labelling (NaBD4) revealed small amounts of glucuronic acid (GlcA). Linkage type analysis by methylation showed that the main components are 1,3,6-Gal(p) and 1,6-Gal(p), as well as there being minor amounts of 1,3-Gal(p), 1,3-Ara(f) and terminal Ara(f), Ara(p), Gal(p) and GlcA(p). We were able to prove this by 13C-NMR spectroscopy data, which led to the following structural proposal:

Fig.1: Structural proposal for LAG

Acknowledgements: We thank Lonza Ltd., Visp (CH) for financial support of this work.

References: 1. Robinson R et al. (2001)J Am Coll Nutr 20: 179–285.

2. D'Adamo P (1996)J Naturopath Med 4: 32–39.