The type A trichothecene mycotoxins T-2 and HT-2 toxin are fungal secondary metabolites produced by Fusarium fungi, which contaminate food and feed worldwide. Especially as a result of the high toxicity of T-2 toxin and their occurrence together with glucosylated forms in cereal crops, these mycotoxins are of human health concern. Particularly, it is unknown whether and how these modified mycotoxins are metabolized in the gastrointestinal tract and, thus, contribute to the overall toxicity. Therefore, the comparative intestinal metabolism of T-2 and HT-2 toxin glucosides in α and β configuration was investigated using the ex vivo pig cecum model, which mimics the human intestinal metabolism. Regardless of its configuration, the C-3 glycosidic bond was hydrolyzed within 10–20 min, releasing T-2 and HT-2 toxin, which were further metabolized to HT-2 toxin and T-2 triol, respectively. We conclude that T-2 and HT-2 toxin should be evaluated together with their modified forms for risk assessment.

Histamine-based imidazole alkaloids N-caprylhistamine (HmC 8 ) and N-caprylhistamine-β-glucoside (HmC 8 -Glc) were recently identified as precursors for a tomato biomarker. As studies regarding metabolism and bioavailability are scarce, the present study aimed at the elucidation of intestinal absorption and metabolism using the Caco-2 model and the pig cecum model to mimic human intestinal conditions. The most abundant imidazole alkaloid HmC 8 -Glc was neither absorbed nor transferred across cellular barriers but extensively metabolized to HmC 8 in the pig cecum model, whereas the aglycon HmC 8 is subjected to transport and metabolic processes through the Caco-2 monolayer and metabolized to the bioactive neurotransmitter histamine by the intestinal microbiota. Deduced from the combined results of both methods, HmC 8 -Glc is not absorbed directly via the intestinal epithelium but requires a metabolic cleavage of the glycosidic bond by the gut microbiota. Because of the high bioavailability of the released HmC 8 and histamine, HmC 8 and its glucoside might also be involved in the intolerance to tomato products by histamineintolerant consumers.

A diet with a high dietary fiber content is often recommended in today's nutrition due to several beneficial health effects related to its intake. Lignin as a part of dietary fiber is the second most abundant natural polymer and considered to be stable during digestion. However, some studies indicate a partial degradation during the intestinal metabolism. To further elucidate this hypothesis, the aim of this study was to investigate whether lignin is metabolized by the gut microbiota using the ex vivo pig cecum model. As potential lignin-derived metabolites might already naturally occur in the pig cecal matrix, an approach using isotopically labeled 13 C lignin was chosen for this study. Ten small phenolic lignin degradation products and their time-dependent metabolism were identified via an untargeted HPLC-HRMS approach, and the quantity of the metabolites was estimated. From the results, we conclude that lignin is partially degraded releasing small phenolic metabolites.

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