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Low or No Inhibitory Potency of the Canonical Galectin Carbohydrate-binding Site by Pectins and Galactomannans

Author:
  • John Stegmayr
  • Adriana Lepur
  • Barbro Kahl Knutson
  • Matilde Aguilar-Moncayo
  • Anatole A. Klyosov
  • Robert A. Field
  • Stina Oredsson
  • Ulf Nilsson
  • Hakon Leffler
Publishing year: 2016
Language: English
Pages: 13318-13334
Publication/Series: Journal of Biological Chemistry
Volume: 291
Issue: 25
Document type: Journal article
Publisher: ASBMB

Abstract english

Some complex plant-derived polysaccharides, such as modified citrus pectins and galactomannans, have been shown to have promising anti-inflammatory and anti-cancer effects. Most reports propose or claim that these effects are due to interaction of the polysaccharides with galectins because the polysaccharides contain galactose-containing side chains that might bind this class of lectin. However, their direct binding to and/or inhibition of the evolutionarily conserved galactoside-binding site of galectins has not been demonstrated. Using a well established fluorescence anisotropy assay, we tested the direct interaction of several such polysaccharides with physiological concentrations of a panel of galectins. The bioactive pectic samples tested were very poor inhibitors of the canonical galactoside-binding site for the tested galectins, with IC50 values >10 mg/ml for a few or in most cases no inhibitory activity at all. The galactomannan Davanat® was more active, albeit not a strong inhibitor (IC50 values ranging from 3 to 20 mg/ml depending on the galectin). Pure synthetic oligosaccharide fragments found in the side chains and backbone of pectins and galactomannans were additionally tested. The most commonly found galactan configuration in pectins had no inhibition of the galectins tested. Galactosylated tri- and pentamannosides, representing the structure of Davanat®, had an inhibitory effect of galectins comparable with that of free galactose. Further evaluation using cell-based assays, indirectly linked to galectin-3 inhibition, showed no inhibition of galectin-3 by the polysaccharides. These data suggest that the physiological effects of these plant polysaccharides are not due to inhibition of the canonical galectin carbohydrate-binding site.

Keywords

  • Cell and Molecular Biology

Other

Published
  • ISSN: 1083-351X
Stina Oredsson
E-mail: stina [dot] oredsson [at] biol [dot] lu [dot] se

Professor

Functional zoology

+46 46 222 94 97

B-C208

4

Principal investigator

LUCC - Lund University Cancer Centre

Research group

Animal Physiology

Projects

Cell proliferation

Doctoral students and postdocs

PhD Students, main supervisor

Wendy Soria Sotillo

PhD Students, assistant supervisor

Atena Malakpour Permlid