Efficacy of Tunisian montmorillonite for in vitro aflatoxin binding and in vivo amelioration of physiological alterations
Applied Clay Science 42 (2008) 151–157
Abstract
Aflatoxins (AFs), a group of closely related, extremely toxic mycotoxins produced by Aspergillus flavus and A. parasiticus, can occur as natural contaminants of food and feeds. AFs have been shown to be hepatotoxic, carcinogenic, mutagenic and teratogenic to different animal species. In the current study Tunisian montmorillonite (TM) was evaluated versus AFs caused toxicities in human colon cancer cell line (Caco-2) and in rats as a
sensitive model. The aims of this study were threefold: (1) to evaluate the efficacy of TM to adsorb AFs from aqueous solution, (2) to protect Caco-2 cell line against AFs-induced cytotoxicity, DNA fragmentation and caspase-3-dependent apoptosis induction and (3) to evaluate the protective effect of TM against AFs toxicity in Sprague–Dawley rats. In the in vitro study, three concentrations of TM (0.5, 1, and 2 mg/L aqueous solution) and three
concentrations of AFB1 (10, 20, 50 mg/L) were tested. The results indicated that TM had a high capacity of adsorbing AFB1 at different concentrations tested. The quantity adsorbed was 19.26 mg of AFB1/g of TM. TM protects Caco-2 cells, inhibits DNA fragmentation and reduces caspase-3 enzymes activity in aflatoxin-treated Caco-2 cell culture. The in vivo results indicated that rats fed AFs-contaminated diet (2.5 mg kg−1 diet) for 2 weeks showed severe serum biochemical changes typical of aflatoxicosis. Rats treated with TM alone (5%) or in combination with aflatoxin were comparable to the control. The TM was found to be safe and successful in the prevention of aflatoxin toxicity and cytotoxicity.
[...]
The basis of interest in the biological effects of montmorillonite
concerns one or more of their physical and chemical properties,
such as ion exchange capacity, adsorption and related molecular
sieve properties. In a previouswork, Abbès et al. (2006a,b, 2007a)
demonstrated that the administration of clayminerals at a levels as
high as 5 g/kg b.w did not show any toxic effects that were
measured using biochemical, haematological, and immunological
parameters in mice. In the same respect, Chung et al. (1990)
demonstrated that the addition ofmontmorillonite (20 g/kg diet) to
chicken feed did not show any toxicity. According to Wiles et al.
(2004), the mixed feed with 20 g of clay/kg diet provided to
pregnant rats did not show any toxicological effects after a long
exposure.Wang et al. (2005) demonstrated that the addition of 1.5
or 3 mg/kg diet daily for 14 days did not show any toxic effects in
the equilibrium of vitamins and minerals in human blood.
Actually there are a variety of commercial adsorbents available
on the market in the form of feed additives. Many of thesemay be
nonselective in their action and may pose significant hidden risks
due to interaction with nutrients and other important feed borne
chemicals [...]
[...]
Recently,
Abbès et al. (2007a) indicated that TM has a good ability to
adsorb heavy metals and protect mice against immunotoxicological
effect of cadmium.
This study has shown that TM alone does not have a negative
impact on biochemical and immunological parameters. The non
toxic effect of montmorillonite was evaluated in series of research
efforts carried out by us or other investigators (Chung et al., 1990)
in chickens, (Wiles et al., 2004) in pregnant rats, (Abdel-Wahhab
et al., 2005a) in Tilapia fish, (Wang et al., 2005) in humans and in
mice (Abbès et al., 2007b).
In conclusion, the results of the current study indicated that
montmorillonite has a high affinity for AFB1 in vitro and forms
a stable adsorption complex. Montmorillonite is non toxic and
effective to reduce the bioavailability of AFs in vitro and in the
gastrointestinal tract, and prevents its biochemical and immunological
toxicity. Montmorillonite can be used as an ‘inorganic
sponge’ sequestering AFs in the gastrointestinal tract of farm
animals.
