Chemical and Conformational Study of the Interactions Involved in Mycotoxin Complexation with β-d-Glucans

Abstract

In a previous paper we reported that beta-D-glucans isolated from Saccharomyces cerevisiae could adsorb zearalenone, reduce its bioavailability in the digestive tract, and protect animals against its adverse effects. We have now investigated, in vitro, the kinetics of the interaction between other mycotoxins and beta-D-glucans from several sources at three pH values found along the digestive tract (3.0, 6.0, and 8.0). Acid and neutral conditions gave the highest affinity rates for aflatoxins B1 > deoxynivalenol > ochratoxin A and involved both the (1 --> 3)-beta-D-glucans and the (1 --> 6)-beta-D-glucans. Alkaline conditions, owing to their destructuring action on glucans, were favorable only for the adsorption of patulin. Using molecular mechanics, we found that hydroxyl, ketone, and lactone groups are involved in the formation of both hydrogen bonds and van der Waals interactions between aflatoxins B1, deoxynivalenol and patulin, and beta-D-glucans. Differences in the binding capacity of the mycotoxins are due to their specific physical and chemical characteristics.

The Effect of Mycotoxins Adsorbents Beta Glucans or Montmorillonite on Bovine Ruminal Fermentation In Vitro

“…As principais glucanas que constituem a parede celular de S. cerevisae são os β-glucanos com ligações glicosídi-cas β-1,3 e β-1,6 [20]. No rúmen, algumas bactérias podem produzir β-1,3 glucanases que rompem essa complexa estrutura e disponibiliza moléculas de glicose para o metabolismo bacteriano [12].…”

“…As ligações β (1-3 e 1-6) e a estruturação tridimensional em forma de hélice, habilitam esse polissacarídeo a adsorver algumas micotoxinas de forma eficiente. As interações entre zearalenona e β-glu ocorrem por meio de ligações de hidrogênio e através de pontes de van der Waals [20]. De outra maneira, MMTs adsorvem AFB1 através de ligações iônicas de sódio ou cálcio que estão ligando as camadas destes filosilicatos [4].…”

Effects of β-glucan on some environmental toxins: An overview

“…Using molecular methods, it was revealed that hydroxyl, lactone and ketone groups participated in formation of hydrogen bonds and van der Walls interactions between glucan and aflatoxin B1 (ref. 11 ). The first investigations of glucan as a decontaminant used insoluble glucans isolated from Saccharomyces cerevisiae 12 .…”

Yeast (Saccharomyces cerevisiae) Glucan Polysaccharides – Occurrence, Separation and Application in Food, Feed and Health Industries

“…Mycotoxins (the first group) are the by-products of the secondary metabolism of pathogenic fungi (Bennet & Klich, 2003), whereas chemical toxins (the second group) are incorporated into plant tissue as a result of plants metabolizing agrochemicals from the soil or water used for irrigation (McLean & Bledsoe, 1992). Some of the most problematic mycotoxins in causing human or animal diseases (i.e., aflatoxin, citrinin, ergot alkaloids, fumonisins, ochratoxin A, patulin, trichothecenes and zeralenone; Smith et al, 1995) can be absorbed by yeast cell wall -glucans (Yiannikouris et al, 2004;Yannikouris et al, 2006). A mixture of cell wall -glucan with clay (bentonite) sold as Mycosorb® by Alltech Inc. offers a spectrum of mycotoxin absorption superior to that of yeast cell wall glucans alone and also absorbs heavy metals (Brady et al, 1994).…”