Dietary clay in the chemoprevention of aflatoxin-induced disease

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http://toxsci.oupjournals.org/cgi/content/abstract/52/2/118

Toxicological Sciences, Vol 52, 118-126, Copyright © 1999 by Society

of Toxicology

ARTICLES

Dietary clay in the chemoprevention of aflatoxin-induced disease

TD

Faculty of Toxicology, Department of Veterinary Anatomy and Public

Health, College of Veterinary Medicine, Texas A & M University,

College Station 77843-4458, USA. tphillips@...

Aflatoxins are harmful by-products of mold growth and, though

invisible to the naked eye, are potentially fatal. The aflatoxin

problem is long- standing and inextricable. Concerns about the

aflatoxins originate from the strong implications of their

involvement in disease and death in humans and animals, yet

scientists and clinicians are still seeking ways to effectively deal

with these dangerous and elusive chemicals. Safe, practical, and

effective strategies for the detoxification of aflatoxin-

contaminated food and feed are highly desirable. A simple and

effective approach to the chemoprevention of aflatoxicosis has been

to diminish or block exposure to aflatoxins via the inclusion of

HSCAS clay in the diet. HSCAS clay acts as an aflatoxin

enterosorbent that tightly and selectively binds these poisons in

the gastrointestinal tract of animals, decreasing their

bioavailability and associated toxicities. Further studies to

delineate the molecular mechanisms of action have shown that the

dicarbonyl system of aflatoxin is essential for tight binding by

HSCAS. In these studies, adsorption data was fitted to multiple

isotherm equations including the Langmuir, multi- Langmuir, general

Freundlich, Langmuir-Freundlich, Toth and various transforms.

Information derived included: the Gibbs standard free energy change

of adsorption, enthalpy of adsorption, capacity, affinity, and

heterogeneity coefficient. Computer modeling was also utilized to

provide additional structural information and insight into the

mechanism. Evidence suggests that aflatoxins may react at multiple

sites on HSCAS particles, especially the interlayer region, but also

at edges and basal surfaces. Since clay and zeolitic minerals

comprise a broad family of functionally diverse chemicals, there may

be significant hidden risks associated with their indiscriminate

inclusion in the diet. All aflatoxin binding agents should be

rigorously tested, paying particular attention to their

effectiveness and safety in aflatoxin-sensitive animals and their

potential for interactions with critical nutrients.

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