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Generation of oxygen free radicals during the metabolism of cyclosporine A: a cause-effect relationship with metabolism inhibition
- Source :
- Molecular and cellular biochemistry. 122(2)
- Publication Year :
- 1993
-
Abstract
- A better understanding of the mechanism of lipid peroxidation during the metabolism of cyclosporine A (CsA) might help explain the toxicities of this immunosuppressive drug on various organs. Our in vitro work used microsomes prepared from livers of phenobarbital-induced male rats. The incubations (total volume 1ml) also contained a NADPH regenerating system and substrate (i.e., CsA, carbon tetrachloride, or aminopyrine) dissolved in ethanol. Lipid peroxidation was inferred from the presence of malondialdehyde (MDA) which was detected by the thiobarbituric acid assay. The formation of CsA hydroxylated metabolites (AM9 and AM1) was monitored by liquid chromatography. The activity of the microsomal incubation was confirmed by measurements of MDA and formaldehyde production caused by increasing concentrations of CsA, carbon tetrachloride, and aminopyrine. The occurrence of hydroxylated metabolites was not coupled to the production of MDA. Aminopyrine could inhibit MDA production by CsA, but CsA could not reduce the formation of formaldehyde by aminopyrine. Erythromycin, a competitor for the binding site of CsA on cytochrome P450, reduced MDA production by CsA, and CsA inhibited formaldehyde production by erythromycin. Interaction studies with SKF 525A, ketoconazole, superoxide dismutase, catalase, alpha-tocopherol, and reduced glutathione confirmed the role of cytochrome P450 and the presence of activated oxygen species as a source of microsomal peroxidation which in return may explain the inhibitory effect of CsA on cytochrome P450 itself.
- Subjects :
- Male
Free Radicals
Thiobarbituric acid
Clinical Biochemistry
Lipid peroxidation
Superoxide dismutase
Rats, Sprague-Dawley
chemistry.chemical_compound
Cytochrome P-450 Enzyme System
Animals
Aminopyrine
Molecular Biology
Carbon Tetrachloride
biology
Chemistry
Superoxide Dismutase
Proadifen
Cytochrome P450
Cell Biology
General Medicine
Glutathione
Malondialdehyde
Catalase
Erythromycin
Rats
Chloramphenicol
Ketoconazole
Biochemistry
biology.protein
Microsome
Cyclosporine
Lipid Peroxidation
Reactive Oxygen Species
Subjects
Details
- ISSN :
- 03008177
- Volume :
- 122
- Issue :
- 2
- Database :
- OpenAIRE
- Journal :
- Molecular and cellular biochemistry
- Accession number :
- edsair.doi.dedup.....641e14a2bbd017d85cbb6d27e815faf7