Efficient Aflatoxin B1 Sequestration by Yeast Cell Wall Extract and Hydrated Sodium Calcium Aluminosilicate Evaluated Using a Multimodal In-Vitro and Ex-Vivo Methodology

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.

Saccharomyces cerevisiae Cell Wall-Based Adsorbent Reduces Aflatoxin B1 Absorption in Rats

“…Our results revealed that the two adsorbents exhibited a highly significant propensity for maintaining higher toxin concentrations in the digestive compartment at both tested time points. This finding confirmed the ability of the adsorbents to limit the intestinal bioavailability of AFB1, leading to a decrease in the absorption of 3 H-AFB1 through the intestine, which further confirmed the previously studied direct [25,46] and indirect mitigation effects observed in various animal species [31,32,44].…”

“…In our study, we were able to highlight both binders' capacity in significantly decreasing the plasma concentration of AFB1 in rats subjected to dietary AFB1 exposure (Figure 5a). We can draw a parallel between this finding and recent findings obtained employing a bicameral Ussing chamber system in an ex vivo setup, in which a reduction in the transfer of AFB1 through the rat intestinal explants led to a decrease in the concentration of AFB1 in the serosal compartment following the use of both YCW and HSCAS [25]. Interestingly, when comparing the 5-and 10-h post-feeding timepoints of the present study, further accumulation of AFB1 could be observed over time, which was effectively prevented by both YCW and HSCAS.…”

“…This in vitro experiment differed from previous experimental methods, as it focused on fieldlevels of AFB1 concentrations in the sub-parts per million range. We confirmed the capacity of both materials to interact with AFB1 effectively, and that the affinity of interaction in the domain of definition of the tested concentration was almost linear, as defined by the slope of the curve using the Freundlich model, the model previously identified as most suited for comparing adsorbents of different nature [24,25]. This model generally defines adsorption events occurring on heterogeneous surfaces, making it more appropriate for a study of both YCW and HSCAS than the Langmuir equation, which is intended for gassolid interaction [52].…”

“…This model generally defines adsorption events occurring on heterogeneous surfaces, making it more appropriate for a study of both YCW and HSCAS than the Langmuir equation, which is intended for gassolid interaction [52]. Hill's equation with n sites has been defined as a suitable equation to characterize cooperative phenomena that considers the dynamic changes influencing the number of binding sites on an adsorbent, which is particularly suitable for the study of YCW, as shown previously for different types of mycotoxins [25,53]. In the present study, little difference was observed among the various models owing to the linear behavior of the relationship between free and bound AFB1 at equilibrium, for the tested concentrations.…”

“…Thus, the quantity of bioavailable mycotoxin reaching an animal tissues or organs, and concomitantly impairing animal health, is reduced [19]. Several mycotoxin binders, particularly a yeast cell wall-based adsorbent (YCW), have shown the ability to successfully adsorb different groups of mycotoxins, as demonstrated by in silico computational mechanistic studies characterizing their chemical interactions [20][21][22], in an in vitro study characterizing their kinetics in reaction media [23], and in ex vivo studies using intestinal tissues [24,25]. Multiple in vivo studies of various animal species have shown the mitigation capabilities of binders following the administration of synthetic or natural mycotoxins via diet, whereas the binder's efficacy has been appraised based on an observed improvement in animal performance [26][27][28].…”