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5149614 
Journal Article 
3-Hydroxy-7,8-dihydro-7,8-dihydroxybenzo(a)pyrene: A Biliary Metabolite of 3-Hydroxybenzo(a)pyrene in the Rat 
Ribeiro, O; Kirkby, CA; Hirom, PC; Millburn, P 
1986 
Yes 
Biochemical Society Transactions
ISSN: 0300-5127
EISSN: 1470-8752 
PORTLAND PRESS 
LONDON 
14 
305-305 
WOS:A1986C013300078 
Biliary metabolites of 3-hydroxybenzo(a)pyrene (13345216) (3OHBP) were studied in rats. Female Lewis-rats with cannulated bile ducts were given 50mg/kg of tritium labeled 3OHBP intraperitoneally. Bile was collected and analyzed for metabolites. Each rat excreted 10 to 15 percent of the dose in bile over a 5 hour period. Benzo(a)pyrene-3,6-quinone (3067149) and 3OHBP were positively identified in chromatographic fractions. Two unidentified peaks isolated from the ethyl-acetate extracts of beta-glucuronidase and aryl-sulfatase hydrolyzed bile were found. One was identified as a triol, 3-hydroxy-7,8-dihydro-7,8-dihydroxybenzo(a)pyrene (BPtriol). The other was provisionally identified as 3,5-dihydroxybenzo(a)pyrene. Bile duct cannulated rats were administered 4 micromoles/kilogram labeled 3OHBP intravenously, and bile was collected and analyzed for metabolites. Approximately 70 percent of the dose was eliminated in the bile in 2 hours, predominantly as three metabolites. These were the sulfate and glucuronic-acid conjugates of 3OHBP and a double conjugate of BPtriol. The BPtriol appeared to be conjugated with sulfate on the three position and glucuronic-acid on either the seven position or the eight position. The authors suggest that in the intestinal tract, this biliary conjugate could be metabolized to free BPtriol, which could then undergo bioactivation to a BPtriol-epoxide. The triol-epoxide is thought to be involved in forming highly reactive intermediates that are involved in metabolic activation of chemical carcinogens.