Alternariol 9-methyl ether

Alternaria mycotoxins, including alternariol (AOH), alternariol-9-monomethylether (AME), and their masked/modified derivatives (e.g., sulfates or glycosides), are common food contaminants. Their acute toxicity is relatively low, while chronic exposure can lead to the development of adverse health effects. Masked/modified metabolites can probably release the more toxic parent mycotoxin due to their enzymatic hydrolysis in the intestines. Previously, we demonstrated the complex formation of AOH with serum albumins and cyclodextrins; these interactions were successfully applied for the extraction of AOH from aqueous matrices (including beverages). Therefore, in this study, the interactions of AME, alternariol-3-sulfate (AS), and alternariol-9-monomethylether-3-sulfate (AMS) were investigated with albumins (human, bovine, porcine, and rat) and with cyclodextrins (sulfobutylether-β-cyclodextrin, sugammadex, and cyclodextrin bead polymers). Our major results/conclusions are the following: (1) The stability of mycotoxin-albumin complexes showed only minor species dependent variations. (2) AS and AMS formed highly stable complexes with albumins in a wide pH range, while AME-albumin interactions preferred alkaline conditions. (3) AME formed more stable complexes with the cyclodextrins examined than AS and AMS. (4) Beta-cyclodextrin bead polymer proved to be highly suitable for the extraction of AME, AS, and AMS from aqueous solution. (5) Albumins and cyclodextrins are promising binders of the mycotoxins tested.

Alternariol (AOH), alternariol monomethyl-ether (AME), and tenuazonic acid (TeA) are major mycotoxins produced by fungi of the genus Alternaria and are common contaminants of food products such as fruits, vegetables, cereals and grains. Alternaria mycotoxins are known to cause relevant economic losses and to have a negative impact on human and animal health. EFSA stated in its scientific opinion that data on the toxicity of Alternaria mycotoxins in humans and livestock are generally lacking, precluding proper hazard characterization. This study aimed to fill some knowledge gaps by studying the in vitro cytotoxicity toward human intestinal epithelial cells (Caco-2) and hepatocytes (HepG2). Cytotoxic properties were assessed by flow cytometric analyses of remaining viable cells (i.e., propidium iodide negative) after mycotoxin exposure for 24-48 h versus solvent control. Treatment of cells with single doses of AOH, AME, and TeA resulted in a dose-dependent loss of cell viability for both cell lines. Half maximal effective concentrations (EC50) of the different mycotoxins were comparable for the two cell lines. On HepG2 cells, EC50 values varying between 8 and 16, 4 and 5, and 40 and 95 μg/mL were calculated for AOH, AME, and TeA, respectively. On Caco-2 cells, EC50 values of 19 μg/mL and varying between 6 and 23, and 60 and 90 μg/mL were calculated for AOH, AME, and TeA, respectively. A general relative cytotoxicity ranking of about 1 = 1 >>> 3 was obtained for AOH, AME, and TeA, respectively. Treatment of both cell lines with combined binary and ternary mixtures of AOH, AME, and TeA in a 1:1:3 ratio, also showed a dose-dependent decrease in cell viability. For both cell lines, the binary combination of especially AME and TeA (1:3 ratio) but also of AOH and AME (1:1 ratio) significantly increased the cytotoxicity compared to the single compound toxicity, although mainly at the highest concentrations tested. The ternary combinations of AOH, AME, and TeA induced only a slight increase in cytotoxicity compared to the single mycotoxins, again at the highest concentrations tested.

Alternariol monomethyl ether (AME), a typical Alternaria toxin, has often been detected in grains. We have measured the general toxicity and genotoxicity of AME with a 28-day multi-endpoint (Pig-a assay + in vivo micronucleus [MN] test + comet assay) platform. Male Sprague-Dawley rats were administered AME (1.84, 3.67, or 7.35 μg/kg body weight/day), N-Ethyl-N-nitrosourea (40 mg/kg body weight/day), or corn oil by gavage for 28 consecutive days. Another group (AME-high-dose + recovery) was maintained for a further 14 days after the end of the AME administration. Hematology and serum biochemistry results suggested that AME might compromise the immune system. The histopathology results indicated that AME can cause liver (inflammatory cell infiltration, steatosis, and edema), kidney (renal glomerular atrophy), and spleen (white pulp atrophy) damage. The genotoxicity results showed that AME can induce gene mutations, chromosome breakage, and DNA damage, but the effects were diminished after the recovery period. According to point-of-departure analysis (BMDL10), the risk to the population of exposure to AME cannot be ignored and further assessment is needed.