Download pectin-bioactivity-abstract

Probing specific interactions between pectin-derived
galactooligosaccharides and the mammalian lectin galectin
3 – testing a model for pectin bioactivity.
VJ Morris, RJM Bongaerts & AP Gunning.
Institute of Food Research, Norwich Research Park, Coney, Norwich NR4 7UA, UK
Pectin is an integral component of non-graminaceous plant cell walls and is a source of both
soluble and insoluble fibre. Pectin is also present in processed foods where it functions as a
gelling agent or a stabiliser in acidic milk drinks. In addition to the health benefits associated
with its role as dietary fibre new aspects of pectin bioactivity are emerging. There is a
growing interest in the role of natural polysaccharides present in the diet in moderating
cancer progression and metastasis1 and one of the most characterised bioactive roles for
pectin is the potential use of a physically modified form of citrus pectin (MCP) as an anticancer agent1. A molecular model has been proposed as a hypothesis for explaining pectin
bioactivity1 suggests that modification pectin causes release, or predisposes release during
digestion, of fragments of pectin which can bind to, and inhibit the roles of the mammalian
lectin galectin 3 (Gal3). Gal3 regulates key stages in the development and spread of
cancers2: these steps include the adhesion of cancer cells to tissue, the growth of blood
vessels to tumours (angiogenesis) and factors which enhance the survival of cancer cells,
such as self-association (emboli formation) and resistance to programmed cell death
(apoptosis). This study reports the use of force spectroscopy to investigate potential specific
interactions between pectin-derived fragments and Gal3. The present studies confirm earlier
work3 that showed that structural modifications that enhance the availability of pectrin-derived
galactooligosaccharides generate fragments that bind specifically to Gal3. The article will
discuss the roles of modification, digestion and the implications of such specific binding on
the bioactivity of modified pectins as anti-cancer agents.
References:
1. Nangia-Makker, P., Conklin, J., Hogan, V. and Raz, A. (2002). Carbohydrate-binding proteins in
cancer, and their ligands as therapeutic agents Trends Mol. Med., 8, 187-192.
2. Glinsky, V.V. and Raz, A. (2009). Modified citrus pectin anti-metastatic properties: one bullet,
multiple targets. Carbohydrate Research, 344, 1788–1791.
3. Gunning, A.P., Bongaerts, R.J.M. and Morris, V.J. (2009). Recognition of galactan components of
pectin by galectin-3. FASEB Journal, 23, 415-424.