Natural Dibenzo-α-Pyrones: Friends or Foes?

Natural dibenzo-α-pyrones (DAPs) can be viewed from two opposite angles. From one angle, the gastrointestinal metabolites urolithins are regarded as beneficial, while from the other, the emerging mycotoxin alternariol and related fungal metabolites are evaluated critically with regards to potential hazardous effects. Thus, the important question is: can the structural characteristics of DAP subgroups be held responsible for distinct bioactivity patterns? If not, certain toxicological and/or pharmacological aspects of natural DAPs might yet await elucidation. Thus, this review focuses on comparing published data on the two groups of natural DAPs regarding both adverse and beneficial effects on human health. Literature on genotoxic, estrogenic, endocrine-disruptive effects, as well as on the induction of the cellular anti-oxidative defense system, anti-inflammatory properties, the inhibition of kinases, the activation of mitophagy and the induction of autophagy, is gathered and critically reviewed. Indeed, comparing published data suggests similar bioactivity profiles of alternariol and urolithin A. Thus, the current stratification into hazardous Alternaria toxins and healthy urolithins seems debatable. An extrapolation of bioactivities to the other DAP sub-class could serve as a promising base for further research. Conclusively, urolithins should be further evaluated toward high-dose toxicity, while alternariol derivatives could be promising chemicals for the development of therapeutics.

Occurrence and bioacessibility of mycotoxins in fish feed.

In this study Aflatoxin B1 (AFB1), ochratoxin A (OTA) and zearalenone (ZEN) occurrence in fish feed, regarding its chemical composition, were investigated. Besides, AFB1 bioaccessibility to fish was evaluated by in vitro digestion. Mycotoxins were extracted by QuEChERS and quantified by HPLC-FLD. Results showed that 93.3% of the samples were contaminated at maximum levels of 16.5, 31.6, and 322 µg/kg in the cases of AFB1, OTA, and ZEN, respectively. A positive correlation between OTA, ZEN contamination, and lipid content was observed. Risk estimation of feed consumption by fish at the highest levels of AFB1, OTA, and ZEN shows that the younger the fish, the higher the risk of exposure to mycotoxins. The AFB1 bioaccessibility assay showed that 85% of this mycotoxin may be absorbed by fish. Therefore, establishing maximum levels in the fishing sector is fundamental to contribute to feed quality and nutritional safety of fish species.

In Vitro Toxicokinetics and Phase I Biotransformation of the Mycotoxin Penitrem A in Dogs.

The tremorgenic mycotoxin penitrem A is produced by Penicillium species as a secondary metabolite on moldy food and feed. Dogs are sometimes exposed to penitrem A by consumption of spoiled food waste or fallen fruit. The lipophilic toxin crosses the blood-brain barrier and targets neuroreceptors and neurotransmitter release mechanisms in the central and peripheral nervous systems. Typical symptoms of penitrem A intoxication are periodical or continuous tremors, which can be passing, persistent or lethal, depending on the absorbed dose. There is presently no information on the biotransformation and toxicokinetics of penitrem A in dogs. The aim of the present study was therefore to identify potential metabolites of the toxin by performing in vitro biotransformation assays in dog liver microsomes. Analyses by liquid chromatography coupled to high-resolution mass spectrometry led to the provisional identification of eleven penitrem A phase I metabolites, which were tentatively characterized as various oxidation products. Furthermore, elimination parameters determined in in vitro assays run under linear kinetics were used for in vitro-to-in vivo extrapolation of the toxicokinetic data, predicting a maximal bioavailability of more than 50%. The metabolite profile detected in the in vitro assays was similar to that observed in the plasma of an intoxicated dog, confirming the predictive capability of the in vitro approach.

Investigating the in vitro catabolic fate of Enniatin B in a human gastrointestinal and colonic model.

Enniatin B is an emerging mycotoxin known to present biological activity because of its ionophoric characteristics. This compound has demonstrated strong in vitro cytotoxicity against different cancer cells, also at low molecular concentrations. Its natural occurrence in food commodities and feed is highly reported world-wide, but few information is available about its stability in the human gastro-intestinal tract. The present work evaluates the catabolic fate of enniatin B upon in vitro simulated digestion and colonic fermentation. LC-MS target and untargeted analysis have been performed to quantify the extent of enniatin B degradation and the formation of catabolic products. The results obtained showed significant degradation of enniatin B (degradation rate 79 ± 5%) along the gastrointestinal tract and further degradation of residual enniatin B was observed during colonic fermentation after 24 h of incubation. Moreover, 5 catabolic metabolites of enniatin B were putatively identified after gastrointestinal digestion resulting from the oxidation and opening of the depsipeptide ring. As a final step, the pharmacokinetic properties of enniatin B degradation products were tested in silico revealing that some of them may be adsorbed at the gastrointestinal level more than the parent compound. Additionally, the smaller degradation products showed moderate blood-brain-barrier crossing.

Comparative toxicokinetics of Fusarium mycotoxins in pigs and humans.

Mycotoxins frequently contaminate food and feed materials, posing a threat to human and animal health. Fusarium species produce important mycotoxins with regard to their occurrence and toxicity, especially deoxynivalenol (DON), fumonisin B1 (FB1), zearalenone (ZEN) and T-2 toxin (T-2). The susceptibility of an animal species towards the effects of these toxins in part depends on the absorption, distribution, metabolism and excretion (ADME processes) of these toxins from the body. For humans, in vivo information is scarce and often animal data is used for extrapolation to humans. From a kinetic and safety point of view, the pig seems to be a promising animal model to aid in the assessment of the toxicological risk of mycotoxins to humans. Qualitatively, the ADME processes seem to be quite similar between pigs and humans. In addition, similar metabolite and excretion patterns are observed, although some quantitative differences are noticed which are subject of this review. The high sensitivity of pigs towards mycotoxins and the similar kinetics are an advantage for the use of this animal species in the risk assessment of mycotoxins, and for the establishment of legal limits of mycotoxins.

Versicolorin A, a precursor in aflatoxins biosynthesis, is a food contaminant toxic for human intestinal cells.

Aflatoxin B1 (AFB1) is the most potent carcinogen among mycotoxins. Its biosynthesis involves the formation of versicolorin A (VerA), whose chemical structure shares many features with AFB1. Our data revealed significant levels of VerA in foodstuff from Central Asia and Africa. Given this emerging food risk, it was of prime interest to compare the toxic effects of the two mycotoxins against cells originating from the intestinal tract. We used human colon cell lines (Caco-2, HCT116) to investigate the cytotoxic process induced by the two mycotoxins. Contrary to AFB1, a low dose of VerA (1 µM) disturbed the expression level of thousands of genes (18 002 genes). We show that the cytotoxic effects of low doses of VerA (1-20 µM) were stronger than the same low doses of AFB1 in both Caco-2 and HCT116 cell lines. In Caco-2 cells, VerA induced DNA strand breaks that led to apoptosis and reduced DNA replication of dividing cells, consequently inhibiting cell proliferation. Although VerA was able to induce the p53 signaling pathway in p53 wild-type HCT116 cells, its toxicity process did not mainly rely on p53 expression since similar cytotoxic effects were also observed in HCT116 cells that do not express p53. In conclusion, this study provides evidence of the risk of food contamination by VerA and shed light on its toxicological effect on human colon cells.

Occurrence and toxicity of a fusarium mycotoxin, zearalenone.

Zearalenone (ZEA) is a mycotoxin produced by the fungi of Fusarium genera, which contaminates the cereals and food stuffs worldwide. Fusarium mycotoxins are considered as important metabolites related to animal and human health. Evidences indicate that ZEA has been found to be present in different food stuffs from developed countries like USA, Canada, France, Germany, Japan, etc. and developing nations like Egypt, Thailand, Iran, Croatia, Philippines, etc. The toxicokinetic studies reveal that following oral exposure of ZEA, the compound is absorbed through gastrointestinal tract (GIT), gets metabolized and distributed to different body parts. ZEA has been shown to cause reproductive disorders in laboratory animals. Although the toxicity of ZEA in humans have not been conclusively established nonetheless, limited evidences indicate that ZEA can cause hyper estrogenic syndrome. Though, ZEA causes low acute toxicity, but reports are available confirming the systemic toxicity caused by ZEA. There is no review available that addresses the occurrence, systemic toxicity and the probable mechanisms of ZEA toxicity. This review shall address the world-wide occurrence and in vivo & in vitro toxicity studies of ZEA over the past 20 years. The review shall also discuss the toxicokinetics of ZEA and metabolites; illustrates the systemic toxicity and probable mechanisms of action leading to the risk associated with ZEA.

Metabolic Profile, Bioavailability and Toxicokinetics of Zearalenone-14-Glucoside in Rats after Oral and Intravenous Administration by Liquid Chromatography High-Resolution Mass Spectrometry and Tandem Mass Spectrometry.

Zearalenone-14-glucoside (ZEN-14G), a key modified mycotoxin, has attracted a great deal of attention due to the possible conversion to its free form of zearalenone (ZEN) exerting toxicity. In this study, the toxicokinetics of ZEN-14G were investigated in rats after oral and intravenous administration. The plasma concentrations of ZEN-14G and its major five metabolites were quantified using a validated liquid chromatography tandem mass spectrometry (LC-MS/MS) method. The data were analyzed via non-compartmental analysis using software WinNonlin 6.3. The results indicated that ZEN-14G was rapidly hydrolyzed into ZEN in vivo. In addition, the major parameters of ZEN-14G following intravenous administration were: area under the plasma concentration-time curve (AUC), 1.80 h·ng/mL; the apparent volume of distribution (VZ), 7.25 L/kg; and total body clearance (CL), 5.02 mL/h/kg, respectively. After oral administration, the typical parameters were: AUC, 0.16 h·ng/mL; VZ, 6.24 mL/kg; and CL, 4.50 mL/h/kg, respectively. The absolute oral bioavailability of ZEN-14G in rats was about 9%, since low levels of ZEN-14G were detected in plasma, which might be attributed to its extensive metabolism. Therefore, liquid chromatography high-resolution mass spectrometry (LC-HRMS) was adopted to clarify the metabolic profile of ZEN-14G in rats' plasma. As a result, eight metabolites were identified in which ZEN-14-glucuronic acid (ZEN-14GlcA) had a large yield from the first time-point and continued accumulating after oral administration, indicating that ZEN-14-glucuronic acid could serve a potential biomarker of ZEN-14G. The obtained outcomes would prompt the accurate safety evaluation of ZEN-14G.

Assessment of Dried Blood Spots for Multi-Mycotoxin Biomarker Analysis in Pigs and Broiler Chickens.

Dried blood spots (DBSs), a micro-sampling technique whereby a drop of blood is collected on filter paper has multiple advantages over conventional blood sampling regarding the sampling itself, as well as transportation and storage. This is the first paper describing the development and validation of a method for the determination of 23 mycotoxins and phase I metabolites in DBSs from pigs and broiler chickens using liquid chromatography-tandem mass spectrometry (LC-MS/MS). The targeted mycotoxins belong to groups for which the occurrence in feed is regulated by the European Union, namely, aflatoxins, ochratoxin A and several Fusarium mycotoxins, and to two groups of unregulated mycotoxins, namely Alternaria mycotoxins and Fusarium mycotoxins (enniatins and beauvericin). The impact of blood haematocrit, DBS sampling volume and size of the analysed DBS disk on the validation results was assessed. No effects of variation in size of the analysed disk, haematocrit and spotted blood volume were observed for most mycotoxins, except for the aflatoxins and ß-zearalanol (BZAL) at the lowest haematocrit (26%) level and for the enniatins (ENNs) at the lowest volume (40 µL). The developed method was transferred to an LC-high resolution mass spectrometry instrument to determine phase II metabolites. Then, the DBS technique was applied in a proof-of-concept toxicokinetic study including a comparison with LC-MS/MS data from plasma obtained with conventional venous blood sampling. A strong correlation (r > 0.947) was observed between plasma and DBS concentrations. Finally, DBSs were also applied in a pilot exposure assessment study to test their applicability under field conditions.

Transport of mycotoxins across human gastric NCI-N87 and intestinal Caco-2 cell models.

Aflatoxin B1 (AFB1), deoxynivalenol (DON), fumonisin B1 (FB1), and ochratoxin A (OTA) are prevalent mycotoxins co-occurring in food, and their oral intake is conceivable to occur in the gastrointestinal epithelium. The intestinal absorption of some mycotoxins has been studied but only considering their isolated intake, while their gastric absorption in humans has not been explored. This study evaluated the bidirectional in vitro transport of four mycotoxins, isolated and in mixture, across gastric NCI-N87 and intestinal Caco-2 monolayers. AFB1 and DON were bidirectionally transported, more rapidly for AFB1; whereas OTA and FB1 were only transported in the absorptive direction, the first in both monolayers, and the second only in the gastric epithelium. The mixture of four mycotoxins exhibited some differences in cell uptake/excretion ratios. AFB1 presented the highest fraction absorbed (>96%) isolated and in mixture, followed by DON (72.8 and 82.9%); and OTA (11 and 66%) when transported isolated and in mixture, respectively. Different absorptive patterns on both epithelia were found when mycotoxins are transported isolated or in mixture. Further investigation on combined ingestion of toxins and their mixed transport should be considered for the proper evaluation of human absorption and toxicity of those mycotoxins considering their frequent co-occurrence and consequent co-exposure.

The In Vivo and In Vitro Toxicokinetics of Citreoviridin Extracted from Penicillium citreonigrum.

Citreoviridin (CTVD), a mycotoxin called yellow rice toxin, is reported to be related to acute cardiac beriberi; however, its toxicokinetics remain unclear. The present study elucidated the toxicokinetics through in vivo experiments in swine and predicted the human toxicokinetics by comparing the findings to those from in vitro experiments. In vivo experiments revealed the high bioavailability of CTVD (116.4%) in swine. An intestinal permeability study using Caco-2 cells to estimate the toxicokinetics in humans showed that CTVD has a high permeability coefficient. When CTVD was incubated with hepatic S9 fraction from swine and humans, hydroxylation and methylation, desaturation, and dihydroxylation derivatives were produced as the predominant metabolites. The levels of these products produced using human S9 were higher than those obtained swine S9, while CTVD glucuronide was produced slowly in human S9 in comparison to swine S9. Furthermore, the elimination of CTVD by human S9 was significantly more rapid in comparison to that by swine S9. These results suggest that CTVD is easily absorbed in swine and that it remains in the body where it is slowly metabolized. In contrast, the absorption of CTVD in humans would be the same as that in swine, although its elimination would be faster.

Biomarkers for Exposure as A Tool for Efficacy Testing of A Mycotoxin Detoxifier in Broiler Chickens and Pigs.

Applying post-harvest control measures such as adding mycotoxin detoxifying agents is a frequently-used mitigation strategy for mycotoxins. EFSA states that the efficacy of these detoxifiers needs to be tested using specific biomarkers for exposure. However, the proposed biomarkers for exposure are not further optimized for specific target species. Hence, the goal of this study was a) to evaluate the most suitable biomarkers for deoxynivalenol (DON) and zearalenone (ZEN) in porcine plasma, urine and feces; and DON, aflatoxin B1 (AFB1) and ochratoxin A (OTA) in plasma and excreta of broiler chickens and b) to determine the efficacy of a candidate detoxifier, as a proof-of-concept study. Therefore, a mixture of mycotoxins was administered as a single oral bolus with or without detoxifying agent. In accordance with literature AFB1, OTA, and DON-sulphate (DON-S) proved optimal biomarkers in broilers plasma and excreta whereas, in pigs DON-glucuronide (DON-GlcA) and ZEN-glucuronide (ZEN-GlcA) proved the optimal biomarkers in plasma, DON and ZEN-GlcA in urine and, ZEN in feces. A statistically significant reduction was seen between control and treatment group for both AFB1 and DON in broiler plasma, under administration of the mycotoxin blend and detoxifier dose studied suggesting thus, beneficial bioactivity.

Metabolism of nivalenol and nivalenol-3-glucoside in rats.

Plant-derived mycotoxin conjugates like deoxynivalenol-3-glucoside can be partly hydrolyzed to their aglycones in vivo, albeit to different extent depending on the mycotoxin conjugate and on the animal species. The aim of this work was to investigate the metabolization of the trichothecene mycotoxin nivalenol (NIV) and the fate of its modified form NIV-3-glucoside (NIV3G) in rats. To that end, 350 µg/kg body weight of NIV and the equimolar dose of NIV3G were administered to six rats by gavage in a 5 × 6 design and excreta were collected for 2 days after each treatment. For further analysis of NIV and NIV3G metabolites in rat urine and feces, seven novel NIV- and NIV3G metabolites including NIV sulfonates (NIVS) 1, 2 and 3, deepoxy-NIV (DNIV), DNIV sulfonate 2, NIV3G sulfonate (NIV3GS) 2 and NIV-3-glucuronide were produced, isolated and characterized. Subsequently, LC-MS/MS based methods for determination of NIV, NIV3G and their metabolites in excreta samples were developed, validated and applied. The biological recoveries of administered toxins in the form of their fecal and urinary metabolites were 57 ± 21% for NIV and 94 ± 36% for NIV3G. The majority of NIV and NIV3G metabolites was excreted into feces, with DNIV and NIVS 2 as major NIV metabolites and NIV3GS 2 and DNIV as major metabolites of NIV3G. Only 1.5% of the administered NIV3G was recovered in urine, with NIV3G itself as major urinary metabolite. The biological recovery of free NIV in urine was approximately 30 times lower after treatment with NIV3G than after administration of NIV, indicating that exposure of rats to NIV3G results in lower toxicity than exposure to NIV.

Interaction between the three frequently co-occurring Fusarium mycotoxins in rats.

To test the complex, acute biochemical effects of combined, naturally co-occurring fusariotoxins, a 5-day rat study was performed. Mycotoxin treatment was invented by intraperitoneal injection: FB1 (F): 9 µg/animal/day (approx. 30 µg/kg bw/day), DON (D): 16.5 µg/animal/day (approx. 55 µg/kg bw/day) and ZEN (Z): 12.75 µg/animal/day (approx. 42.5 µg/kg bw/day). The binary groups (FB1 and DON [FD], FB1 and ZEN [FZ] and DON and ZEN [DZ]) as well as the ternary (FB1 , DON and ZEN [FDZ]) group were dosed at the same combined level as the individual mycotoxins. Body weight, feed intake and mortality were not affected by any of the treatments. FB1 and DON in combination (FD) increased the plasma aspartate aminotransferase activity synergistically (compared to the individual FB1 and DON). In the liver, both the total glutathione (GSH) and the glutathione peroxidase (GPx) activity were increased (p < 0.05) by the binary FB1 and ZEN (FZ) and the DON and ZEN (DZ) groups as well as the ternary FB1 , DON and ZEA group (FDZ) compared to the control. The GSH level of the ternary group was significantly increased compared to the FB1 group, whereas the GPx activity of the ternary group was significantly increased compared to all three the individual mycotoxin groups. The Bliss independence method revealed synergism between DON and ZEN (DZ), as well as FB1 and DON (FD) on liver GPx activity. None of the toxins alone or in combination exerted strong genotoxicity on lymphocytes, neither on the gross histopathological characteristics. However, even at these low levels acute exposure of more than one of these mycotoxins (FB1 , DON and ZEN) affected metabolic and detoxification changes.

Fusarium mycotoxins and in vitro species-specific approach with porcine intestinal and brain in vitro barriers: A review.

Fusarium mycotoxins, such as fumonisins, trichothecenes, zearalenone and emerging fusariotoxins, common contaminants of feed and food, have received increased interest, due to the possible impact on animal and human health. In this context, it is urgent to focus our attention on fusariotoxins adverse effects, considering and analysing data in relation to their species-specificity. The in vitro approach for fusariotoxins risk assessment evaluation, through porcine epithelial barriers model, allowed to collect information on their absorption profile, bioavailability and toxicity. The aim of this review is to give an overview on Fusarium mycotoxins and their interactions with porcine intestinal and brain in vitro barriers, because they represent direct target organs of toxicity and as tools to evaluate their permeability and transport.

Pharmacokinetic Properties of the Nephrotoxin Orellanine in Rats.

Orellanine is a nephrotoxin found in mushrooms of the Cortinarius family. Accidental intake of this substance may cause renal failure. Orellanine is specific for proximal tubular cells and could, therefore, potentially be used as treatment for metastatic renal cancer, which originates from these cells. However, more information is needed about the distribution and elimination of orellanine from the body to understand its potential use for therapy. In this study, 5 mg/kg orellanine (unlabeled and ³H-labeled) was injected intravenously in rats (Wistar and Sprague Dawley). Distribution was measured (Wistar rats, n = 10, n = 12) using radioluminography and the highest amount of orellanine was found in the kidney cortex and bladder at all time-points investigated. The pharmacokinetic properties of orellanine was investigated using LC-MS/MS and ß-scintillation to measure the amount of orellanine in plasma. Three groups of rats were investigated: control rats with intact kidneys (n = 10) and two groups with bilateral renal artery ligation (n = 7) where animals in one of these groups were treated with peritoneal dialysis (n = 8). Using LC-MS/MS, the half-life of orellanine was found to be 109 ± 6 min in the controls. In the groups with ligated renal arteries, orellanine had a half-life of 756 ± 98 min without and 238 ± 28 min with dialysis. Thus, orellanine was almost exclusively eliminated by glomerular filtration as well as by peritoneal dialysis.

Effects of Feeding a Mycotoxin Binder on Nutrient Digestibility, Alkaloid Recovery in Feces, and Performance of Lambs Fed Diets Contaminated with Cereal Ergot.

As contamination with cereal ergot has been increasing in western Canada, this study evaluated impacts of feeding a mycotoxin binder (Biomin® II; BB) on nutrient digestibility, alkaloid recovery in feces, and lamb growth performance. Forty-eight ram lambs (25.9 ± 1.4 kg) were randomly assigned to one of four barley-based diets: Control (C), no added alkaloids, Control + BB fed at 30 g/head per day (CBB); Ergot, 2564 ppb total R + S epimers (E); Ergot + BB, 2534 ppb R + S epimers (EBB). Lambs were fed ab libitum for up to 11 weeks until slaughter at >46 kg live weight. Both average daily gain (ADG) and gain/feed ratio were greater (p < 0.01) for lambs fed C and CBB diets as compared with those containing added ergot, although dry matter intake was not affected by dietary ergot or BB. Serum prolactin concentrations were two times higher in EBB- compared with E-fed lambs (p < 0.05), although both were lower than in C or CBB (p < 0.001) lambs. Rectal temperatures were greater in lambs receiving dietary ergot (p ≤ 0.001) than in C- and CBB-fed lambs. In a digestibility study using eight ram lambs, treatment with BB increased neutral detergent fiber (NDF) digestibility (p = 0.01). Nitrogen retention (g) was greater (p < 0.05) for lambs receiving C or CBB compared with ergot-contaminated diets. Feces of EBB lambs had 38.5% greater (p < 0.001) recovery of alkaloids compared with those fed E. Based on sparing of prolactin, BB may reduce impacts of ergot alkaloids by increasing their excretion in feces. Accordingly, concentrations of dietary alkaloids, which would not harm sheep, would be increased by feeding BB.

Urinary biomarkers of exposure to the mycoestrogen zearalenone and its modified forms in German adults.

Zearalenone (ZEN), a mycotoxin with estrogenic activity, can exert adverse endocrine effects in mammals and is thus of concern for humans. ZEN is found in cereal crops and grain-based foods, often along with modified ('masked') forms usually not detected in routine contaminant analysis, e.g., ZEN-O-ß-glucosides and ZEN-14-sulfate. These contribute to mycoestrogen exposure, as they are cleaved in the gastrointestinal tract to ZEN, and further metabolized in animals and humans to α- and ß-zearalenol (α-ZEL and ß-ZEL). ZEN and its metabolites are mainly excreted as conjugates in urine, allowing to monitor human exposure by a biomarker-based approach. Here, we report on a new study in German adults (n = 60) where ZEN, α-ZEL, and ß-ZEL were determined by LC-MS/MS analysis after enzymatic hydrolysis and immunoaffinity column clean-up of the aglycones in urines. Biomarkers were detected in all samples: ZEN ranges 0.04-0.28 (mean 0.10 ± 0.05; median 0.07) ng/mL; α-ZEL ranges 0.06-0.45 (mean 0.16 ± 0.07; median 0.13) ng/mL, and ß-ZEL ranges 0.01-0.20 (mean 0.05 ± 0.04; median 0.03) ng/mL. Notably, average urinary levels of α-ZEL, the more potent estrogenic metabolite, are higher than those of ZEN, while ß-ZEL (less estrogenic than ZEN) is found at lower levels than the parent mycotoxin. Similar results were found in ten persons who collected multiple urine samples to gain more insight into temporal fluctuations in ZEN biomarker levels; here some urines had higher maximal concentrations of total ZEN (the sum of ZEN, α-ZEL, and ß-ZEL) with 1.6 and 1.01 ng/mL, i.e., more than those found in the majority of other urines. A preliminary approach to translate the new urinary biomarker data into dietary mycotoxin intake suggests that exposure of most individuals in our cohort is probably below the tolerable daily intake (TDI) of 0.25 µg/kg b.w. set by EFSA as group value for ZEN and its modified forms while that of some individuals exceed it. In conclusion, biomonitoring can help to assess consumer exposure to the estrogenic mycotoxin ZEN and its modified forms and to identify persons at higher risk.

Emerging Fusarium and Alternaria Mycotoxins: Occurrence, Toxicity and Toxicokinetics.

Emerging Fusarium and Alternaria mycotoxins gain more and more interest due to their frequent contamination of food and feed, although in vivo toxicity and toxicokinetic data are limited. Whereas the Fusarium mycotoxins beauvericin, moniliformin and enniatins particularly contaminate grain and grain-based products, Alternaria mycotoxins are also detected in fruits, vegetables and wines. Although contamination levels are usually low (µg/kg range), higher contamination levels of enniatins and tenuazonic acid may occasionally occur. In vitro studies suggest genotoxic effects of enniatins A, A1 and B1, beauvericin, moniliformin, alternariol, alternariol monomethyl ether, altertoxins and stemphyltoxin-III. Furthermore, in vitro studies suggest immunomodulating effects of most emerging toxins and a reproductive health hazard of alternariol, beauvericin and enniatin B. More in vivo toxicity data on the individual and combined effects of these contaminants on reproductive and immune system in both humans and animals is needed to update the risk evaluation by the European Food Safety Authority. Taking into account new occurrence data for tenuazonic acid, the complete oral bioavailability, the low total body clearance in pigs and broiler chickens and the limited toxicity data, a health risk cannot be completely excluded. Besides, some less known Alternaria toxins, especially the genotoxic altertoxins and stemphyltoxin III, should be incorporated in risk evaluation as well.

Do Plant-Bound Masked Mycotoxins Contribute to Toxicity?

Masked mycotoxins are plant metabolites of mycotoxins which co-contaminate common cereal crops. Since their discovery, the question has arisen if they contribute to toxicity either directly or indirectly through the release of the parent mycotoxins. Research in this field is rapidly emerging and the aim of this review is to summarize the latest knowledge on the fate of masked mycotoxins upon ingestion. Fusarium mycotoxins are the most prevalent masked mycotoxins and evidence is mounting that DON3Glc and possibly other masked trichothecenes are stable in conditions prevailing in the upper gut and are not absorbed intact. DON3Glc is also not toxic per se, but is hydrolyzed by colonic microbes and further metabolized to DOM-1 in some individuals. Masked zearalenone is rather more bio-reactive with some evidence on gastric and small intestinal hydrolysis as well as hydrolysis by intestinal epithelium and components of blood. Microbial hydrolysis of ZEN14Glc is almost instantaneous and further metabolism also occurs. Identification of zearalenone metabolites and their fate in the colon are still missing as is further clarification on whether or not masked zearalenone is hydrolyzed by mammalian cells. New masked mycotoxins continuously emerge and it is crucial that we gain detailed understanding of their individual metabolic fate in the body before we can assess synergistic effects and extrapolate the additive risk of all mycotoxins present in food.