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Interaction of benzanthrone with cytochrome P450: altered patterns of hepatic xenobiotic metabolism in rats
- Source :
- Journal of biochemical toxicology. 6(1)
- Publication Year :
- 1991
-
Abstract
- Benzanthrone, an anthraquinone dye intermediate, is commonly used for the synthesis of a number of polycyclic vat and disperse dyes. Our prior studies have shown that benzanthrone can be metabolized by rat hepatic microsomal cytochrome P450 (P450) (Biochem. Int., 18, 1989, 1237). In this study, the interaction of benzanthrone with rat hepatic microsomal P-450 and its effect on xenobiotic metabolism have been investigated. Parenteral administration of benzanthrone (40 mg/kg body weight) for 3, 7, or 21 days caused no change in the relative body weight or organ weight of rats. The levels of P450 were found to be reduced (33%-50%) in all the benzanthrone-exposed animals at all the time periods. In vitro addition of benzanthrone caused a spectral change with oxidized P450 and concentration-dependent reduction in the carbon monoxide spectrum of dithionite-reduced P450. The addition of benzanthrone to hepatic microsomes prepared from phenobarbital-treated rats resulted in spectral changes characterized by an absorbance maximum at 397 nm indicative of type I binding. In vitro addition of benzanthrone showed a concentration-dependent inhibition of hepatic aminopyrine N-demethylase (APD) and ethoxyresorufin-O-deethylase (ERD) activities with respective I50 values of 9.5 × 10−4 and 8.0 × 10−5 M. However, the inhibition of aryl hydrocarbon hydroxylase (AHH) even at the highest concentration of benzanthrone (10−2 M), was of the order of only 29%. In vivo administration of benzanthrone also led to the inhibition of APD, AHH, and ERD activities at all treatment times although the magnitude of inhibition was of a lower order. Benzanthrone treatments caused significant depletion of glutathione content with a concomitant enhancement of lipid peroxidation. Also, benzanthrone resulted in a significant inhibition of the cytosolic enzyme, GSH-transferase (23%–34%), although the other enzyme, quinone reductase, which helps in the removal of toxic quinones, was found to be elevated (184%–199%). These results suggest several mechanisms by which benzanthrone may inhibit P450. This impairment of xenobiotic metabolism as well as the enhancement of lipid peroxidation may be relevant to the observed symptoms of benzanthrone-induced hepatotoxicity.
- Subjects :
- Male
medicine.medical_specialty
Reductase
Toxicology
Kidney
Benzanthrone
Xenobiotics
Lipid peroxidation
chemistry.chemical_compound
Cytosol
Cytochrome P-450 Enzyme System
Internal medicine
medicine
Benz(a)Anthracenes
Animals
Lung
Carbon Monoxide
biology
Body Weight
Cytochrome P450
Dithionite
Rats, Inbred Strains
Glutathione
Organ Size
Monooxygenase
Rats
Endocrinology
Cytochromes b5
chemistry
Biochemistry
Liver
biology.protein
Microsome
Microsomes, Liver
Oxygenases
Lipid Peroxidation
Drug metabolism
Subjects
Details
- ISSN :
- 08872082
- Volume :
- 6
- Issue :
- 1
- Database :
- OpenAIRE
- Journal :
- Journal of biochemical toxicology
- Accession number :
- edsair.doi.dedup.....fd83dde8744638f1f0f0f9604409bea4