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Oxidation of 4-chlorobiphenyl metabolites to electrophilic species by prostaglandin H synthase
Journal article   Open access   Peer reviewed

Oxidation of 4-chlorobiphenyl metabolites to electrophilic species by prostaglandin H synthase

Orarat Wangpradit, Lynn M Teesch, S. V. Santhana Mariappan, Michael W Duffel, Karin Norstrom, Larry W Robertson and Gregor Luthe
Chemical research in toxicology, Vol.22(1), pp.64-71
01/2009
DOI: 10.1021/tx800300t
PMCID: PMC2637223
PMID: 19105592
url
https://doi.org/10.1021/tx800300tView
Published (Version of record) Open Access

Abstract

Hormonally–sensitive tissues, like the prostate, ovary and breast, increasingly studied as targets of environmental chemicals, are sources of an enzyme potentially capable of transforming and activating xenobiotics to highly reactive metabolites. Our study specifically addresses the question of whether prostaglandin H synthase (PGHS) can activate phenolic metabolites of polychlorinated biphenyls (PCBs). We found that human recombinant PGHS-2 catalyzed the oxidation of ortho (2′,3′-, 3′,4′-) and para (2′,5′-) dihydroxy 4-chlorobiphenyl metabolites to their corresponding quinones. These were trapped in situ with N-acetyl cysteine and the reaction products were isolated and characterized by liquid chromatography coupled mass spectrometry and 1 H and heteronuclear ( 1 H- 13 C) nuclear magnetic resonance spectroscopy. Both mono- and di-N-acetyl cysteine Michael addition adducts were identified, with the 2′,3′-, and 2′,5′-dihydroxy metabolites predominantly forming mono-N-acetyl cysteine adducts, while the 3′,4′-dihydroxy predominantly formed di-substituted N-acetyl cysteine adducts. These studies clearly demonstrate that the phenolic metabolites of these environmental pollutants are activated by PGHS, as co-substrates, to highly reactive electrophilic PCB quinones, with a potential for protein and DNA damage, especially in non-hepatic tissues where the enzyme is found.

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