Zeitschrift für Phytotherapie 2023; 44(S 01): S18
DOI: 10.1055/s-0043-1769540
Abstracts

Dose-response studies on the genotoxic potential of estragole and its metabolite 1‘-hydroxyestragole in human liver cells

Authors

  • G Ackermann

    1   Division of Food Chemistry and Toxicology, Department of Chemistry, Technical University of Kaiserslautern, Germany

  • M Peil

    1   Division of Food Chemistry and Toxicology, Department of Chemistry, Technical University of Kaiserslautern, Germany

  • J-H Küpper

    2   Division of Molecular Cell Biology, Department of Environment and Nature Science, Brandenburg University of Technology Cottbus-Senftenberg, Germany

  • D Schrenk

    1   Division of Food Chemistry and Toxicology, Department of Chemistry, Technical University of Kaiserslautern, Germany

  • J Fahrer

    1   Division of Food Chemistry and Toxicology, Department of Chemistry, Technical University of Kaiserslautern, Germany
Further Information
 

Introduction Estragole is a phenylpropene, naturally occurring in essential oils of herbs and spices, mainly bitter fennel, basil or tarragon. Therefore, the main exposure is through food or herbal medicinal products e.g. bitter fennel tea and oil. The alkenylbenzene is fully absorbed via the oral route and transported to the liver. Here it undergoes CYP- and SULT-mediated metabolism, which can give rise to a reactive carbenium ion and subsequent DNA adduct formation.

Objectives Aim of our work is to analyse the dose and time dependent genotoxicity of estragole and its main phase I metabolite 1’-hydroxyestragole using in vitro human liver cell models as well as primary rat hepatocytes, both competent in phase I and/or phase II enzymes.

Material & Methods For investigating the genotoxicity of the alkenylbenzene and its main metabolite, stably transfected HepG2-CYP1A2 and HepG2 wt cells as well as primary rat hepatocytes are used. The test battery includes the resazurin reduction assay to evaluate the cell viability after treatment with the substances. Genotoxic effects such as single and double strand breaks are quantified directly via alkaline comet assay. Furthermore, the surrogate marker γH2AX is detected by western blot analysis as well as confocal immunofluorescence microscopy.

Results Treating the cell lines with the mother substance up to 500 µM at different time points (24, 72 h) showed no effects on the cell viability of our used models, despite HepG2-CYP1A2 and primary rat hepatocytes are competent in formation of the carbenium ion. Consistent with these findings no genotoxic effects regarding DNA strand break induction could be observed in the transfected HepG2-CYP1A2 cells. In contrary the incubation of HepG2 cells with 1’- hydroxyestragole showed a time and dose dependent cytotoxicity (EC50(24 h) = 56.2 µM; EC50(72 h) = 24.7 µM). After 24 h 1’-hydroxyestragole caused concentration-dependent γH2AX formation as confirmed via western blot and immunofluorescence, with a BMDL value of 1.9 µM. Using the alkaline comet assay a low induction of DNA strand breaks was also observed.

Conclusion Even though estragole is a known carcinogen in rodents, we showed that the genotoxic and cytotoxic effects in metabolic competent cells are low. In contrary, its metabolite 1’-hydroxyestragole shows clear genotoxic and cytotoxic effects. To further elucidate the genotoxic potential of the mother substance, the main DNA adducts will be quantified via UHPLC-MS/MS measurements.

AcknowledgementThe project is being supported by Kooperation Phytopharmaka GbR, Bonn.



Publication History

Article published online:
14 June 2023

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