Toxic effects of substituted p-benzoquinones and hydroquinones in in vitro bioassays are altered by reactions with the cell assay medium

Substituted para-benzoquinones and hydroquinones are ubiquitous transformation products that arise during oxidative water treatment of phenolic precursors, for example through ozonation or chlorination. The benzoquinone structural motive is associated with mutagenicity carcinogenicity, also induction the stress response Nrf2 pathway. For either endpoint, toxicological data differently substituted compounds scarce. In this study, response, as indicated by AREc32 in vitro bioassay, was induced para-benzoquinones, but corresponding hydroquinones. Bioassays indicate defense against genotoxicity (p53RE-bla) DNA repair activity (UmuC) were not activated these compounds. Stability tests conducted under incubation conditions, absence cell lines, showed tested reacted rapidly constituents medium. Compounds abated already phosphate buffer, even faster biological media, reactions attributed to amino- thiol-groups peptides, proteins, free amino acids. often Conversely, quantitatively oxidized p-benzoquinones over course incubation. observed presumably benzoquinones inside cells. Despite instability medium, bioassay could be used an unspecific sum parameter detect oxidatively treated waters.