Characterization of metabolic activation of pentachlorophenol to quinones and semiquinones in rodent liver

Pentachlorophenol (PCP), a widely used biocide, induces liver tumors in mic e but not in rats. Metabolic activation of PCP to chlorinated quinones and semiquinones in liver cytosol from Spraque-Dawley rats and B6C3F1 mice was investigated in vitro(1) with microsomes in the presence of either beta -ni cotinamide adenine dinucleotide phosphate (NADPH) or cumene hydroperoxide ( CHP): (2) with CK in the absence of microsomes, and (3) with horseradish pe roxidase (HRP) and H2O2. Mono-S- and multi-S-substituted adducts of tetrach loro-1,4-benzoquinone (Cl-4-1,4-BQ) and Cl-4-1,2-BQ and their corresponding semiquinones [i.e. tetrachloro-1,4-benzosemiquinone (Cl-4-1,4-SQ) and tetr achloro-1:2-benzosemiquinone (Cl-4-1,2-SQ)] were measured by gas chromatogr aphy-mass spectrometry (CrC-MS). Qualitatively, the metabolites of PCP were the same in both rats and mice for all activation systems. Induction of PC P metabolism by either 3MC or PB-treated microsomes