Nathan Broekaert

Modified Fusarium mycotoxins unmasked: from occurrence in cereals to animal and human excretion

Modified mycotoxins formed by plants, fungi and during some food processing steps may remain undetected by analytical methods, potentially causing underestimation of mycotoxin exposure and risk. Furthermore, due to altered physico-chemical characteristics of modified mycotoxins, these compounds might have different gastro-intestinal absorption compared to the unmodified forms, leading to altered modified mycotoxin plasma concentrations. Additionally, modified mycotoxins can be converted back into their corresponding unmodified forms by in vivo hydrolysis upon oral ingestion. This review aims to describe the current knowledge on the production, occurrence, toxicity and toxicokinetic properties of the modified Fusarium mycotoxins. The need for more occurrence data to correctly assess the risks associated with these modified mycotoxins is clearly indicated, including differences between commodities as well as geographical and climatological influences. Research on toxicity of these modified forms demonstrates the possibility of significant decreases as well as increases in the toxic effects of these compounds compared with those of the unmodified forms. Their toxicokinetics demonstrates that a decreased (increased) polarity of modified mycotoxins might cause enhanced (decreased) oral absorption. The possibility of in vivo hydrolysis, altered toxicity and their wide-spread occurrence makes modified mycotoxins a complex threat for which a risk assessment will require prospective multi-disciplinary efforts.

Pilot toxicokinetic study and absolute oral bioavailability of the Fusarium mycotoxin enniatin B1 in pigs

The aim of present study was to reveal the toxicokinetic properties and absolute oral bioavailability of enniatin B1 in pigs. Five pigs were administered this Fusarium mycotoxin per os and intravenously in a two-way cross-over design. The toxicokinetic profile fitted a two-compartmental model. Enniatin B1 is rapidly absorbed after oral administration (T(1/2a)=0.15 h, Tmax=0.24h) and rapidly distributed and eliminated as well (T(1/2elα)=0.15 h; T(1/2elβ)=1.57 h). The absolute oral bioavailability is high (90.9%), indicating a clear systemic exposure. After intravenous administration, the mycotoxin is distributed and eliminated rapidly (T(1/2elα)=0.15 h; T(1/2elβ)=1.13 h), in accordance with oral administration.

Oral Bioavailability, Hydrolysis, and Comparative Toxicokinetics of 3-Acetyldeoxynivalenol and 15-Acetyldeoxynivalenol in Broiler Chickens and Pigs.

The goal of this study was to determine the absolute oral bioavailability, (presystemic) hydrolysis and toxicokinetic characteristics of deoxynivalenol, 3-acetyldeoxynivalenol, and 15-acetyldeoxynivalenol in broiler chickens and pigs. Crossover animal trials were performed with intravenous and oral administration of deoxynivalenol, 3-acetyldeoxynivalenol, and 15-acetyldeoxynivalenol to broilers and pigs. Plasma concentrations were analyzed by using liquid chromatography-tandem mass spectrometry, and data were processed via a tailor-made compartmental toxicokinetic analysis. The results in broiler chickens showed that the absorbed fraction after oral deoxynivalenol, 3-acetyldeoxynivalenol, and 15-acetyldeoxynivalenol administration was 10.6, 18.2, and 42.2%, respectively. This fraction was completely hydrolyzed presystemically for 3-acetyldeoxynivalenol to deoxynivalenol and to a lesser extent (75.4%) for 15-acetyldeoxynivalenol. In pigs, the absorbed fractions were 100% for deoxynivalenol, 3-acetyldeoxynivalenol, and 15-acetyldeoxynivalenol, and both 3-acetyldeoxynivalenol and 15-acetyldeoxynivalenol were completely hydrolyzed presystemically. The disposition properties of 3-acetyldeoxynivalenol and 15-acetyldeoxynivalenol demonstrate their toxicological relevance and consequently the possible need to establish a tolerable daily intake.

Development and validation of an LC-MS/MS method for the toxicokinetic study of deoxynivalenol and its acetylated derivatives in chicken and pig plasma

This study aims to develop an LC-MS/MS method allowing the determination of 3-acetyl-deoxynivalenol, 15-acetyl-deoxynivalenol, deoxynivalenol and its main in vivo metabolite, deepoxy-deoxynivalenol, in broiler chickens and pigs. These species have a high exposure to these toxins, given their mainly cereal based diet. Several sample cleanup strategies were tested and further optimized by means of fractional factorial designs. A simple and straightforward sample preparation method was developed consisting out of a deproteinisation step with acetonitrile, followed by evaporation of the supernatant and reconstitution in water. The method was single laboratory validated according to European guidelines and found to be applicable for the intended purpose, with a linear response up to 200ngml(-1) and limits of quantification of 0.1-2ngml(-1). As a proof of concept, biological samples from a broiler chicken that received either deoxynivalenol, 3- or 15-acetyl-deoxynivalenol were analyzed. Preliminary results indicate nearly complete hydrolysis of 3-acetyl-deoxynivalenol to deoxynivalenol; and to a lesser extent of 15-acetyl-deoxynivalenol to deoxynivalenol. No deepoxy-deoxynivalenol was detected in any of the plasma samples. The method will be applied to study full toxicokinetic properties of deoxynivalenol, 3-acetyl-deoxynivalenol and 15-acetyl-deoxynivalenol in broiler chickens and pigs.

Can the use of coccidiostats in poultry breeding lead to residues in vegetables? An experimental study.

The aim of this study was to provide information on the dietary exposure of the European public to coccidiostats via vegetable consumption. Five groups of poultry followed a three-phase feeding schedule with feed containing the maximum allowed level of a coccidiostat: monensin, lasalocid A, salinomycin, diclazuril, and nicarbazin/narasin, plus one control group. Vegetables were cultivated on soil amended with manure (10 g of fresh weight/kg of soil) from the treated poultry. To mimic a worst-case scenario, vegetables were also grown on soil spiked with coccidiostats. For each vegetable/treatment combination, samples were harvested, freeze-dried, and analyzed using a validated liquid chromatography-tandem mass spectrometry method. Analysis of the vegetables demonstrated that these plants are capable of taking up these coccidiostats from the soil. However, the results indicate that these low incorporation levels, coupled with food consumption data and acceptable daily intakes, are unlikely to pose a direct threat to public health.

Toxicokinetic study and oral bioavailability of deoxynivalenol in turkey poults, and comparative biotransformation between broilers and turkeys

The aim of present study was to reveal the toxicokinetic properties and absolute oral bioavailability of deoxynivalenol (DON) in turkey poults. Six turkey poults were administered this Fusarium mycotoxin per os and intravenously in a two-way cross-over design. Based on non-compartmental analysis, DON was absorbed rapidly (Tmax= 0.57 h) but incomplete, as the oral bioavailability was only 20.9%. DON was rapidly eliminated as well, both after oral (T1/2elimination PO=0.86 h) as well as intravenous (IV) (T1/2elimination IV = 0.62 h) administration. Furthermore, semi-quantitative analysis using high-resolution mass spectrometry revealed that DON-3α-sulphate is the major metabolite of DON in turkeys after IV as well as oral administration, with DON-3α-sulphate/DON ratios between 1.3-12.6 and 32.4-140.8 after IV and oral administration, respectively. Glucuronidation of DON to DON-3α-glucuronide is a minor pathway in turkey poults, with DON-3α-glucuronide/DON ratios between 0.009-0.065 and 0.020-0.481 after IV a...

Quantitative Determination of Tenuazonic Acid in Pig and Broiler Chicken Plasma by LC-MS/MS and Its Comparative Toxicokinetics

A liquid chromatography-tandem mass spectrometry (LC-MS/MS) method to quantitate tenuazonic acid (TeA) in pig and broiler chicken plasma was successfully developed and validated. Linear matrix-matched calibration curves ranged between 5 and 200 ng/mL. Correlation coefficients, goodness-of-fit coefficients, and within-day and between-day precision and accuracy fell well within the acceptance criteria. The limit of quantitation was 5.0 ng/mL in both pig and broiler chicken plasma. The LC-MS/MS method was applied in a comparative toxicokinetic study in both pigs and broiler chickens. TeA was completely bioavailable after oral administration in both animal species. However, absorption was deemed to be slower in broiler chickens (mean tmax 0.32 h in pigs vs 2.60 h in chickens). TeA was more slowly eliminated in broiler chickens (mean t1/2el 0.55 h in pigs vs 2.45 h in chickens after oral administration), mainly due to the significantly lower total body clearance (mean Cl 446.1 mL/h/kg in pigs vs 59.2 mL/h/kg in chickens after oral administration). Tissue residue studies and further research to elucidate the biotransformation and excretion processes of TeA in pigs, broiler chickens, and other animal species are imperative.

In vitro adsorption and in vivo pharmacokinetic interaction between doxycycline and frequently used mycotoxin binders in broiler chickens

Mycotoxin binders are readily mixed in feeds to prevent uptake of mycotoxins by the animal. Concerns were raised for nonspecific binding with orally administered veterinary drugs by the European Food Safety Authority in 2010. This paper describes the screening for in vitro adsorption of doxycycline-a broad-spectrum tetracycline antibiotic-to six different binders that were able to bind >75% of the doxycycline. Next, an in vivo pharmacokinetic interaction study of doxycycline with two of the binders, which demonstrated significant in vitro binding, was performed in broiler chickens using an oral bolus model. It was shown that two montmorillonite-based binders were able to lower the area under the plasma concentration-time curve of doxycycline by >60% compared to the control group. These results may indicate a possible risk for reduced efficacy of doxycycline when used concomitantly with montmorillonite-based mycotoxin binders.

Comparative toxicokinetics, absolute oral bioavailability, and biotransformation of zearalenone in different poultry species.

After oral (PO) and intravenous (IV) administration of zearalenone (ZEN) to broiler chickens, laying hens, and turkey poults, the mycotoxin was rapidly absorbed (Tmax = 0.32-0.97 h) in all three species; however, the absolute oral bioavailability was low (F% = 6.87-10.28%). Next, also a rapid elimination of the mycotoxin in all poultry species was observed (T(1/2el) = 0.29-0.46 h). Both α- and β-zearalenone (ZEL) were formed equally after IV administration in all species studied, whereas an increased biotransformation to β-ZEL was demonstrated after PO administration, indicating presystemic biotransformation mainly in broiler chickens and laying hens. In comparison to the latter, turkey poults demonstrated a more extensive biotransformation of ZEN to α-ZEL after PO administration which could, in combination with the observed higher volume of distribution of ZEN, indicate a higher sensitivity of this species to the effects of ZEN in comparison to other poultry species.

T-2 TOXIN-3α-GLUCOSIDE IN BROILER CHICKENS: TOXICOKINETICS, ABSOLUTE ORAL BIOAVAILABILITY AND IN VIVO HYDROLYSIS

Due to the lack of information on bioavailability and toxicity of modified mycotoxins, current risk assessment on these modified forms assumes an identical toxicity of the modified form to their respective unmodified counterparts. Crossover animal trials were performed with intravenous and oral administration of T-2 toxin (T-2) and T-2 toxin-3α-glucoside (T2-G) to broiler chickens. Plasma concentrations of T2-G, T-2, and main phase I metabolites were quantified using a validated liquid chromatography-tandem mass spectrometry method with a limit of quantitation for all compounds of 0.1 ng/mL. Resulting plasma concentration-time profiles were processed via two-compartmental toxicokinetic models. No T-2 triol and only traces of HT-2 were detected in the plasma samples after both intravenous and oral administration. The results indicate that T-2 has a low absolute oral bioavailability of 2.17 ± 1.80%. For T2-G, an absorbed fraction of the dose and absolute oral bioavailability of 10.4 ± 8.7% and 10.1 ± 8.5% were observed, respectively. This slight difference is caused by a minimal (and neglectable) presystemic hydrolysis of T2-G to T-2, that is, 3.49 ± 1.19%. Although low, the absorbed fraction of T2-G is 5 times higher than that of T-2. These differences in toxicokinetics parameters between T-2 and T2-G clearly indicate the flaw in assuming equal bioavailability and/or toxicity of modified and free mycotoxins in current risk assessments.