Potential Metabolic Activation of a Representative C4-Alkylated Polycyclic Aromatic Hydrocarbon Retene (1-Methyl-7-isopropyl-phenanthrene) Associated with the Deepwater Horizon Oil Spill in Human Hepatoma (HepG2) Cells

Meng Huang, Clementina Mesaros, Linda C. Hackfeld, Richard P. Hodge, Tianzhu Zang, Ian A. Blair, Trevor M. Penning

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Exposure to petrogenic polycyclic aromatic hydrocarbons (PPAHs) in the food chain is the major human health hazard associated with the Deepwater Horizon oil spill. C4-Phenanthrenes are representative PPAHs present in the crude oil and could contaminate the seafood. We describe the metabolism of a C4-phenanthrene regioisomer retene (1-methyl-7-isopropyl-phenanthrene) in human HepG2 cells as a model for metabolism in human hepatocytes. Retene because of its sites of alkylation cannot be metabolized to a diol-epoxide. The structures of the metabolites were identified by HPLC-UV-fluorescence detection and LC-MS/MS. O-Monosulfonated-retene-catechols were discovered as signature metabolites of the ortho-quinone pathway of PAH activation catalyzed by aldo-keto reductases. We also found evidence for the formation of bis-ortho-quinones where the two dicarbonyl groups were present on different rings of retene. The identification of O-monosulfonated-retene-catechol and O-bismethyl-O-monoglucuronosyl-retene-bis-catechol supports metabolic activation of retene by P450 and aldo-keto reductase isozymes followed by metabolic detoxification of the ortho-quinone through interception of redox cycling by catechol-O-methyltransferase, uridine 5′-diphospho-glucuronosyltransferase, and sulfotransferase isozymes. We propose that catechol conjugates could be used as biomarkers of human exposure to retene resulting from oil spills.

Original languageEnglish (US)
Pages (from-to)1093-1101
Number of pages9
JournalChemical Research in Toxicology
Issue number4
StatePublished - Apr 17 2017


ASJC Scopus subject areas

  • Toxicology

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