*Article* **The Food Contaminants Pyrrolizidine Alkaloids Disturb Bile Acid Homeostasis Structure-Dependently in the Human Hepatoma Cell Line HepaRG**

**Josephin Glück 1, Marcus Henricsson 2, Albert Braeuning <sup>1</sup> and Stefanie Hessel-Pras 1,\***

<sup>1</sup> Department of Food Safety, German Federal Institute for Risk Assessment, Max-Dohrn-Straße 8-10, 10589 Berlin, Germany; josephin.glueck@bfr.bund.de (J.G.); albert.braeuning@bfr.bund.de (A.B.)

**\*** Correspondence: stefanie.hessel-pras@bfr.bund.de; Tel.: +49-30-18412-25203

**Abstract:** Pyrrolizidine alkaloids (PAs) are a group of secondary plant metabolites being contained in various plant species. The consumption of contaminated food can lead to acute intoxications in humans and exert severe hepatotoxicity. The development of jaundice and elevated bile acid concentrations in blood have been reported in acute human PA intoxication, indicating a connection between PA exposure and the induction of cholestasis. Additionally, it is considered that differences in toxicity of individual PAs is based on their individual chemical structures. Therefore, we aimed to elucidate the structure-dependent disturbance of bile acid homeostasis by PAs in the human hepatoma cell line HepaRG. A set of 14 different PAs, including representatives of all major structural characteristics, namely, the four different necine bases retronecine, heliotridine, otonecine and platynecine and different grades of esterification, was analyzed in regard to the expression of genes involved in bile acid synthesis, metabolism and transport. Additionally, intra- and extracellular bile acid levels were analyzed after PA treatment. In summary, our data show significant structuredependent effects of PAs on bile acid homeostasis. Especially PAs of diester type caused the strongest dysregulation of expression of genes associated with cholestasis and led to a strong decrease of intraand extracellular bile acid concentrations.

**Keywords:** pyrrolizidine alkaloids; structure dependency; hepatotoxicity; cholestasis; bile acids
