Recognition of galactan components of pectin by galectin-3

Institute of Food Research, Norwich Research Park, Colney, Norwich NR4 7UA, UK.
The FASEB Journal (Impact Factor: 5.04). 11/2008; 23(2):415-24. DOI: 10.1096/fj.08-106617
Source: PubMed


It has been reported that modified forms of pectin possess anticancer activity. To account for this bioactivity, it has been proposed that fragments of pectin molecules can act by binding to and inhibiting the various roles of the mammalian protein galectin 3 (Gal3) in cancer progression and metastasis. Despite this clear molecular hypothesis and evidence for the bioactivity of modified pectin, the structural origins of the "bioactive fragments" of pectin molecules are currently ill defined. By using a combination of fluorescence microscopy, flow cytometry, and force spectroscopy, it has been possible to demonstrate, for the first time, specific binding of a pectin galactan to the recombinant form of human Gal3. Present studies suggest that bioactivity resides in the neutral sugar side chains of pectin polysaccharides and that these components could be isolated and modified to optimize bioactivity.

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    • "Pectins from okra and potato are rich in RG-I structures (Cheng et al., 2013; Vayssade et al., 2010), which all have antitumor activity. Experimental results from fluorescence microscopy , fluorescence-activated cell sorting (FACS) and atomic force microscopy (AFM) show that galactan from pectin fragments can bind human recombinant Gal-3 (Gunning et al., 2009). The dissociation coefficient between b-D-galactobiose and Gal-3 is 0.33 s À1 (Gunning, Pin, & Morris, 2013). "
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    ABSTRACT: Pectin, a complex class of plant polysaccharides, is composed of a galacturonan backbone and neutral sugar side chains. Natural pectin is reported to prevent colon cancer as a dietary fiber (DF). To enhance its bioavailability and bioactivity, pectin was modified into bioavailable modified pectin fragments (MPs) with low molecular mass. Also, MPs had low degrees of esterification (DE) which is reported to inhibit tumor growth, induce apoptosis, suppress metastasis, and modulate immunological responses. Antitumor activity of MPs chiefly arises from intervention in ligand recognition by galectin-3 (Gal-3). In addition, pectin is a suitable vehicle for anti-cancer drug delivery systems, due to its abundant modifiable functional groups and special physicochemical properties. Here, we summarize the structural features, bio-absorption and antitumor mechanisms and the structure-activity relationship of MPs. We also offer prospects and challenges for developing pectin into nutraceuticals or drugs.
    No preview · Article · Apr 2015 · Trends in Food Science & Technology
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    • "The water-soluble fiber, pectin, is used in jam-making and has an anticancer effect in medicine. It is shown that fragments of pectin bind to and inhibit galectin 3 (Gal3), which is a protein that has an important role in cancer progression [78]. "

    Full-text · Chapter · May 2014
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    • "Gunning et al. (2013) confirmed that neutral galactan side chains did selectively bind to recombinant galectin-3. These active fragments can be obtained by enzymatic treatment of isolated RG-I regions from potato pectin (Gunning et al., 2009). "
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    ABSTRACT: Despite enormous efforts that have been made in the search for novel drugs and treatments, cancer continues to be a major public health problem. Moreover, the emergence of resistance to cancer chemotherapy often prevents complete remission. Researchers have thus turned to natural products mainly from plant origin to circumvent resistance. Pectin and pH- or heat-modified pectin have demonstrated chemopreventive and antitumoral activities against some aggressive and recurrent cancers. The focus of this review is to describe how pectin and modified pectin display these activities and what are the possible underlying mechanisms. The failure of conventional chemotherapy to reduce mortality as well as serious side effects make natural products, such as pectin-derived products, ideal candidates for exerting synergism in combination with conventional anticancer drugs.
    Full-text · Article · Oct 2013 · Frontiers in Pharmacology
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