INVESTIGADORES
MONGE Maria Del Pilar
artículos
Título:
Negligible effects of tryptophan on the aflatoxin adsorption of sodium bentonite
Autor/es:
A. P. MAGNOLI; P. COPIA; M.P. MONGE; C. E.MAGNOLI; A. M. DALCERO; S.M. CHIACCHIERA
Revista:
FOOD ADDITIVES AND CONTAMINANTS
Editorial:
TAYLOR & FRANCIS LTD
Referencias:
Lugar: Londres; Año: 2014
ISSN:
0265-203X
Resumen:
The main objective of this study was to determine if the competitive adsorption of tryptophan
(Trp) and aflatoxin B1 (AFB1) could potentially affect the ability of a sodium bentonite (NaB)
to prevent aflatoxicosis in monogastric animals. The adsorption of Trp and AFB1 on this
adsorbent is fast and could be operating on the same time-scale making competition feasible.
In vitro competitive adsorption experiments under simulated gastrointestinal conditions were
performed. A high affinity of the clay for Trp and NaB was observed. The effect of an excess
of KCl to mimic the ionic strength of the physiological conditions were also investigated. A
six times decrease in the Trp surface excess at saturation was observed. A similar behavior
was previously found for AFB1 adsorption. Taking into account the amount of Trp adsorbed
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Accepted Manuscript
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by the clay and the usual adsorbent supplementation level in diets, a decrease in Trp
bioavailability is not expected to occur. Tryptophan adsorption isotherms on NaB were Sshaped
and were adjusted by the Frumkin-Fowler-Guggenheim model. The reversibility of
the adsorption processes was investigated in order to check a potential decrease in the ability
of NaB to protect birds against chronic aflatoxicoses. Adsorption processes were completely
reversible for Trp, while almost irreversible for AFB1. In spite of the high affinity of the NaB
for Trp, probably due to the reversible character of Trp adsorption, no changes in the AFB1
adsorption isotherm were observed when an excess of the amino acid was added to the
adsorption medium. As a consequence of the preferential and irreversible AFB1 adsorption
and the reversible weak binding of Trp to the NaB, no changes in the aflatoxin sorption ability
of the clay are expected to occur in the gastrointestinal tract of birds.