Coumarin chemoprotection against aflatoxin B1-induced gene mutation in a mammalian cell system: A species difference in mutagen activation and protection with chick embryo and rat liver S9

Douglas E. Goeger, Karl E. Andersen, Abraham W. Hsie

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15 Scopus citations


Coumarin (1,2-benzopyrone), a natural food constituent, prevents polycyclic aromatic hydrocarbon-induced neoplasms in rats-and mice, but has not been studied with other chemical carcinogens. We examined coumarin chemoprotection against aflatoxin B1 using the 6-thioguanine resistance mutation assay in two different Chinese hamster ovary cell lines (K1BH4 and AS52) with liver S9 from rats and 1 9-day-old chick embryos for aflatoxin latoxi n B1 bioactivation. Laboratory rodents metabolize coumarin through 3-hydroxylation, whereas 7-hydroxylation predominates in chick embryos and humans. Chick embryo liver S9 was approximately 25-fold more effective in activating aflatoxin B1 to the mutagenic and cytotoxic metabolite(s) than rat liver S9. Coumarin added at 50 and 500 μM with chick embryo liver S9 reduced the mutant frequency of 1 μM aflatoxin B1 by 40 and 85%, respectively. Coumarin up to 500 μM had no effect on aflatoxin n B1 mutagenicity with rot liver 89. When liver 89 from chick embryos pretreated with coumarin was used for aflatoxin B1 bioactivation, mutant frequency and cytotoxicity were decreased compared to liver S9 from vehicle-treated controls. Liver S9 from coumarin-treated rats did not significantly affect mutant frequency or cytotoxicity. HPLC analysis of chick embryo liver 89 incubated with 1 μM aflatoxin B1 showed a dose-dependent de crease by coumarin of aflatoxin B1 activation to the 8,9-epoxide ranging from 70% of controls at 5 μM coumarin to 4% of controls at 500 μM coumarin. In contrast, coumarin produced a dose-dependent increase in 20 μM aflatoxin B1 activation by rat liver S9, reaching twice the control levels at 500 μM coumarin. These findings, using a mammalian cell system as a mutagenic endpoint, demonstrate marked species differences in chemoprotection by coumarin.

Original languageEnglish (US)
Pages (from-to)64-74
Number of pages11
JournalEnvironmental and Molecular Mutagenesis
Issue number1
StatePublished - Aug 25 1998


  • 6-Thioguanine resistance
  • Aflatoxin B
  • Chemoprevention
  • Coumarin
  • Liver S9
  • Mutation assay

ASJC Scopus subject areas

  • Epidemiology
  • Genetics(clinical)
  • Health, Toxicology and Mutagenesis


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