Degradation of patulin in rats and humans quantified by stable isotope dilution assays: A review

Up to now, little is known about absorption and metabolism of the mycotoxin patulin. Therefore, in a first series of experiments the absorption of patulin in the tissue of perfused rat stomachs and its vascular appearance after luminal application was quantified by a stable isotope dilution assay. The new method involves the use of [13C2]-patulin as the internal standard, trimethylsilylation of patulin isotopomers and detection of patulin derivatives by GC-MS. After application of juices, to which patulin at doses of 350 and 3.5 mg/l, respectively, had been added, the mycotoxin appeared almost instantly in the perfusate. Additionally, the luminal disappearance of the mycotoxin could be attributed in part to its addition to intracellular glutathione (GSH). Regarding the GSH content in the tissue, a decrease of 87% compared to that of control stomachs was observed for the high PAT dose, whereas in case of the low patulin dose no significant GSH decrease occurred. In further studies, the absorption and degradation of patulin in humans was investigated. No patulin was found in the serum of a volunteer, whose blood was drawn shortly after consumption of a juice containing 50 μg/l patulin. Subsequent in-vitro assays showed that after addition of patulin to human whole blood, only 6.1% of the mycotoxin was detected after 2 min at 37 °C. It was concluded that, even high naturally occurring concentrations of patulin in foods are quickly degraded in the gastro intestinal tract before reaching other tissues. Possible reaction products were investigated. In model experiments of patulin with blood, glutathione adducts of the mycotoxin were identified in the blood. However, local toxic effects on the tissues of stomach and intestine still have to be considered, in particular as the majority of reaction products of PAT in organisms are still unknown.