Studies on the chromatographic fractionation of metabolites of benzo[a]pyrene in faeces and urine from germfree and conventional rats

Börje Egestad, Per Pettersson, Jan Sjövall, Joseph Rafter, Kaija Hyvönen, Jan-Ake Gustafsson

Research output: Contribution to journalArticlepeer-review

15 Scopus citations

Abstract

Rats, germfree and conventional, were dosed with 14C-labelled benzo[a]pyrene. Faeces and urine were collected. Metabolites in faeces were effectively extracted with a new method using a combination of solvents and solid sorbents. Metabolites in urine were extracted with octadecylsilane-bonded silica. The metabolites were fractionated into groups by chromatography on a cation exchanger (SP-LH-20 or SP-Sephadex C-25) and an anion exchanger (TEAP-LH-20). Some of the groups were further purified by column chromatography and analysed by HPLC and TLC. The analyses show a complex pattern of metabolism. A large part of the metabolites (9-24% depending on animal type and route of excretion) had amphoteric properties, e.g. like glutathione and cysteine conjugates. The abundance of conjugates sensitive to β-glucuronidase and sulphatase was low. The relative amount of acidic conjugates in faeces was much higher in the germfree than in the conventional rats indicating the influence of the intestinal flora on the metabolism. The results support the view that the mercapturic acid pathway is a quantitatively important metabolic route for benzo[a]pyrine in rats. The methods of extraction and group fractionation were designed to be generally applicable to the analysis of lipophilic xenobiotics and their metabolites.

Original languageEnglish (US)
Pages (from-to)120-134
Number of pages15
JournalBiomedical Chromatography
Volume2
Issue number3
DOIs
StatePublished - Jan 1 1987

ASJC Scopus subject areas

  • Analytical Chemistry
  • Biochemistry
  • Molecular Biology
  • Pharmacology
  • Drug Discovery
  • Clinical Biochemistry

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