Studies on mechanism of genotoxicity of selected pyrrolizidine alkaloids in HepG2 cells in vitro

Introduction Pyrrolizidine alkaloids (PAs) are phytotoxins that have been discovered in various plant families. Certain PAs are hepatotoxic and genotoxic and are potentially harmful to humans via food, food supplements and herbs/spices. PAs can cause hepatic sinusoidal obstruction syndrome and are carcinogenic in animals. Here we investigated the chemical structure effect relationship of several genotoxic PAs.

Methodology The genotoxicity of PAs of different esterification types, such as europine, retrorsine and lasiocarpine, was determined in HepG2 cells using the cytokinesis-block micronucleus (CBMN) assay. DNA-crosslinking activity of different PA-types was investigated using a modified comet assay. The role of metabolic enzymes such as cytochrome P450s was investigated by using the inhibitor ketoconazole.

Results An increase of micronucleus formation was found with all tested PAs of different chemical structure. The lowest concentrations at which significant induction of micronuclei were detected were 3.2 µM for lasiocarpine (open diester type), 32 µM for retrorsine (cyclic diester type) and 100 µM for europine (monoester type). In the modified crosslink comet assay, the diester type PAs reduced tail formation after hydrogen peroxide treatment, while an equimolar concentration of the monoester europine did not significantly reduce DNA migration. In addition, micronucleus induction by lasiocarpine was abolished after pre-treatment with the cytochrome P450 inhibitor ketoconazole.

Conclusion The results strengthen the hypothesis that the genotoxicic potential depends on the ester type of the PAs with the open diester PA-type being the most potent while the monoester PA-type being the least potent. In the modified comet assay, the crosslinking activity was also related to the ester type of PAs.

• Reference

• 1 Hadi NSA. et al. Mutat Res 2021; 861-862: 503305. DOI: 10.1016/j.mrgentox.2020.503305.

Publikationsverlauf

Artikel online veröffentlicht:
22. Juni 2021