Abstract
In this work, adsorption of the carcinogenic mycotoxin aflatoxin B1 (AFB1) by two sequestrants—a yeast cell wall-based adsorbent (YCW) and a hydrated sodium calcium aluminosilicate (HSCAS)—was studied across four laboratory models: (1) an in vitro model from a reference method was employed to quantify the sorption capabilities of both sequestrants under buffer conditions at two pH values using liquid chromatography with fluorescence detection (LC-FLD); (2) in a second in vitro model, the influence of the upper gastrointestinal environment on the mycotoxin sorption capacity of the same two sequestrants was studied using a chronic AFB1 level commonly encountered in the field (10 µg/L and in the presence of feed); (3) the third model used a novel ex vivo approach to measure the absorption of 3H-labelled AFB1 in the intestinal tissue and the ability of the sequestrants to offset this process; and (4) a second previously developed ex vivo model readapted to AFB1 was used to measure the transfer of 3H-labelled AFB1 through live intestinal tissue, and the influence of sequestrants on its bioavailability by means of an Ussing chamber system. Despite some sorption effects caused by the feed itself studied in the second model, both in vitro models established that the adsorption capacity of both YCW and HSCAS is promoted at a low acidic pH. Ex vivo Models 3 and 4 showed that the same tested material formed a protective barrier on the epithelial mucosa and that they significantly reduced the transfer of AFB1 through live intestinal tissue. The results indicate that, by reducing the transmembrane transfer rate and reducing over 60% of the concentration of free AFB1, both products are able to significantly limit the bioavailability of AFB1. Moreover, there were limited differences between YCW and HSCAS in their sorption capacities. The inclusion of YCW in the dietary ration could have a positive influence in reducing AFB1′s physiological bioavailability.
Highlights
Aflatoxins have been found to contaminate a variety of agricultural products, such as maize and other small-grain cereal crops, both pre-harvest and during storage
According to Freundlich data fitting, the adsorption capacity (Kf) and intensity were comparable for both yeast cell wall-based adsorbent (YCW) and hydrated sodium calcium aluminosilicate (HSCAS) (Table 1), with higher capacity and intensity coefficient observed for YCW at pH 3.0 than for HSCAS and higher capacity for HSCAS but a lower intensity compared with YCW at pH 7.0
The in vitro evaluation of YCW and HSCAS demonstrated the capacity of both adsorbents to effectively interact with aflatoxin B1 (AFB1), as demonstrated in Models 1 and 2
Summary
Aflatoxins have been found to contaminate a variety of agricultural products, such as maize and other small-grain cereal crops, both pre-harvest and during storage. Aspergillus spp. within the section Flavi are principal producers of aflatoxins [1], fungal secondary metabolites (mycotoxins) that include aflatoxin B1 (AFB1), aflatoxin B2, aflatoxin G1, and aflatoxin G2 [2]. Within the section Flavi are principal producers of aflatoxins [1], fungal secondary metabolites (mycotoxins) that include aflatoxin B1 (AFB1), aflatoxin B2, aflatoxin G1, and aflatoxin G2 [2] While these are regarded as the four most significant mycotoxins in the class [3], AFB1 is the most potent of the group, and the effects of its consumption have been well characterised [4]. AFB1 is passively absorbed through the gastrointestinal mucosa at a very high rate [5,6] and, due to its lipophilic nature, is characteristically sequestered in the liver. AFB0 is responsible for most of the toxicity of AFB1, forming adducts with DNA (AFB1 N7-guanine) and proteins (AFB1 Lys) within the cell, leading to significant macromolecular disruption [4,8]
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