Exposure to aristolochic acid (AA) is associated with human nephropathy and urothelial cancer. Individual susceptibility to AA-induced disease likely reflects individual differences in enzymes that metabolize AA. Herein, we evaluated AAI metabolism by human cytochrome P450 (CYP) 1A1 and 1A2 in two CYP1A-humanized mouse lines that carry functional human CYP1A1 and CYP1A2 genes in the absence of the mouse Cyp1a1/1a2 orthologs. Human and mouse hepatic microsomes and human CYPs were also studied. Human CYP1A1 and 1A2 were found to be principally responsible for reductive activation of AAI to form AAI-DNA adducts and for oxidative detoxication to 8-hydroxyaristolochic acid (AAIa), both in the intact mouse and in microsomes. Overall, AAI-DNA adduct levels were higher in CYP1A-humanized mice relative to wild-type mice, indicating that expression of human CYP1A1 and 1A2 in mice leads to higher AAI bioactivation than in mice containing the mouse CYP1A1 and 1A2 orthologs. Furthermore, an exclusive role of human CYP1A1 and 1A2 in AAI oxidation to AAIa was observed in human liver microsomes under the aerobic (i.e., oxidative) conditions. Because CYP1A2 levels in human liver are at least 100-fold greater than those of CYP1A1 and there exists a > 60-fold genetic variation in CYP1A2 levels in human populations, the role of CYP1A2 in AAI metabolism is clinically relevant. The results suggest that, in addition to CYP1A1 and 1A2 expression levels, in vivo oxygen concentration in specific tissues might affect the balance between AAI nitroreduction and demethylation, which in turn would influence tissue-specific toxicity or carcinogenicity.

• MeSH
• adukty DNA metabolismus   MeSH
• cytochrom P-450 CYP1A1 antagonisté a inhibitory   genetika   metabolismus   MeSH
• cytochrom P-450 CYP1A2 genetika   metabolismus   MeSH
• cytosol enzymologie   MeSH
• dealkylace MeSH
• inhibitory cytochromu P450 CYP1A2 MeSH
• inhibitory enzymů farmakologie   MeSH
• jaterní mikrozomy enzymologie   MeSH
• játra účinky léků   enzymologie   MeSH
• karcinogeny metabolismus   toxicita   MeSH
• kyseliny aristolochové metabolismus   toxicita   moč   MeSH
• lidé MeSH
• metabolická inaktivace MeSH
• myši inbrední C57BL MeSH
• myši knockoutované MeSH
• myši transgenní MeSH
• myši MeSH
• oxidace-redukce MeSH
• rekombinantní proteiny metabolismus   MeSH
• urologické nádory chemicky indukované   MeSH
• urotel účinky léků   MeSH
• vysokoúčinná kapalinová chromatografie MeSH
• zvířata MeSH
• Check Tag
• lidé MeSH
• myši MeSH
• ženské pohlaví MeSH
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• Research Support, N.I.H., Extramural MeSH

OBJECTIVES: To study the contribution of individual purified porcine CYP1A2, 2E1 and 2A19 enzymes to the biotransformation of skatole. METHODS: Individual porcine and human enzymes (CYP1A2, 2E1 or 2A6/19) were used to study their potential involvement in skatole metabolism. Furthermore, the inhibition experiments using specific inhibitors of CYP1A2, 2E1 or 2A6/19, were performed. For determination of skatole biotransformation by individual CYP forms in reconstituted systems, HPLC method with UV detection was used. RESULTS: The data presented in this paper show that porcine and human CYPs are responsible for the formation of indole-3-carbinol and 3-methyloxindole. Whereas in pig CYP2A19 and CYP1A2 seem to be the most important for metabolism of skatole, in man CYP1A2 and CYP2E1 forms are mainly responsible for the production of the metabolites mentioned above. CONCLUSIONS: The porcine and human CYP1A2, 2E1, 2A6/19 forms contribute to formation of 3-methyloxindole and indole-3-carbinol.

• MeSH
• cytochrom P-450 CYP1A2 metabolismus   MeSH
• cytochrom P-450 CYP2E1 metabolismus   MeSH
• indoly metabolismus   MeSH
• inhibitory cytochromu P450 CYP1A2 MeSH
• inhibitory cytochromu P450 CYP2E1 MeSH
• inhibitory cytochromu P450 MeSH
• lidé MeSH
• prasata MeSH
• skatol metabolismus   MeSH
• systém (enzymů) cytochromů P-450 metabolismus   MeSH
• zvířata MeSH
• Check Tag
• lidé MeSH
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH

Olomoucine II is a cyclin-dependent kinase inhibitor and a potential antineoplastic agent because it can arrest animal cell cycles. This study examines its interactions with human liver microsomal cytochrome P450 (P450) enzymes. Spectroscopic and high-performance liquid chromatography (HPLC) methods were used to estimate the degree of olomoucine II-mediated inhibition of enzymatic activities of eight drug-metabolizing P450s in vitro. In addition, mass spectrometry coupled with HPLC was used to identify an olomoucine II metabolite (2,5-dihydroxyroscovitine) formed in the reaction mixtures, and CYP3A4 was found to be responsible for the hydroxylation of the N(6)-benzyl ring at position 5, leading to this compound. Olomoucine II significantly inhibited the enzymatic activities of CYP1A2, CYP2C9, and (to a lesser degree) CYP3A4. The results indicate that use of olomoucine II as a drug could affect the activities of CYP3A4, CYP1A2, and CYP2C9 in vivo. Hence, the clinical relevance of these interactions should be carefully evaluated.

• MeSH
• aromatické hydroxylasy antagonisté a inhibitory   MeSH
• cytochrom P-450 CYP1A2 MeSH
• cytochrom P-450 CYP3A MeSH
• inhibiční proteiny cyklin-dependentních kinas farmakologie   MeSH
• inhibitory cytochromu P450 CYP1A2 MeSH
• inhibitory cytochromu P450 CYP3A MeSH
• inhibitory cytochromu P450 MeSH
• jaterní mikrozomy enzymologie   účinky léků   MeSH
• játra cytologie   enzymologie   MeSH
• lékové interakce MeSH
• lidé MeSH
• N-demethylasy MeSH
• protinádorové látky farmakologie   MeSH
• puriny farmakologie   MeSH
• substrátová specifita MeSH
• systém (enzymů) cytochromů P-450 MeSH
• vysokoúčinná kapalinová chromatografie MeSH
• Check Tag
• lidé MeSH
• Publikační typ
• práce podpořená grantem MeSH

Silybin (a flavonolignan, the main component of silymarin, an extract from the seeds of Silybum marianum) has been used to date mostly as a hepatoprotectant. However, it also has other interesting activities, e.g., anticancer and hypocholesterolemic effects. It is also known that silybin can inhibit the activities of the cytochrome P450 (P450) enzymes. In this study, a weak interaction of silybin with human microsomal CYP2E1, 2A6, 2B6, 2C19, and 2D6 (IC(50) > or = 250 microM) was found; a moderate inhibition was observed for CYP1A2 and 2C8. The most prominent inhibition effect was found with CYP3A4 and CYP2C9 (IC(50) < or = 50 microM). Using mass spectometry detection, production of O-demethylated (the main metabolite) as well as hydroxylated derivatives of silybin formed by P450 enzymes was detected. The effect of different P450 inhibitors on the formation of O-demethylated product was also studied. In particular, a relatively specific inhibitor of CYP2C8 (quercetin) markedly inhibited the formation of this metabolite. With the help of recombinant enzymes (bactosomes), it was confirmed that the CYP2C8 enzyme is responsible for the reaction leading to O-demethylated silybin.

• MeSH
• antioxidancia farmakologie   metabolismus   MeSH
• aromatické hydroxylasy antagonisté a inhibitory   genetika   metabolismus   MeSH
• cytochrom P-450 CYP1A2 genetika   metabolismus   MeSH
• cytochrom P-450 CYP3A MeSH
• Escherichia coli genetika   metabolismus   MeSH
• financování organizované MeSH
• inhibitory cytochromu P450 CYP1A2 MeSH
• inhibitory cytochromu P450 MeSH
• inhibitory enzymů farmakologie   metabolismus   MeSH
• jaterní mikrozomy enzymologie   metabolismus   účinky léků   MeSH
• katalýza účinky léků   MeSH
• lidé MeSH
• molekulární struktura MeSH
• oxid uhelnatý farmakologie   MeSH
• quercetin farmakologie   MeSH
• rekombinantní proteiny metabolismus   MeSH
• silymarin farmakologie   chemie   metabolismus   MeSH
• systém (enzymů) cytochromů P-450 genetika   metabolismus   MeSH
• vysokoúčinná kapalinová chromatografie MeSH
• Check Tag
• lidé MeSH

Quaternary benzo[c]phenanthridine alkaloids (QBA) sanguinarine and chelerythrine exhibit a wide spectrum of biological activities whence they are used in dental care products. Recent studies indicated that cytochrome P450 CYP1A attenuates sanguinarine toxicity both in vivo [Williams, M.K., Dalvi, S., Dalvi, R.R., 2000. Influence of 3-methylcholanthrene pretreatment on sanguinarine toxicity in mice. Vet. Hum. Toxicol. 42, 196-198] and in vitro [Vrba, J., Kosina, P., Ulrichová, J., Modrianský, M., 2004. Involvement of cytochrome P450 1A in sanguinarine detoxication. Toxicol. Lett. 151, 375-387]. However, CYP1A converts sanguinarine to the products that form DNA adducts [Stiborová, M., Simánek, V., Frei, E., Hobza, P., Ulrichová, J., 2002. DNA adduct formation from quaternary benzo[c]phenanthridine alkaloids sanguinarine and chelerythrine as revealed by the 32P-postlabeling technique. Chem. Biol. Interact. 140, 231-242]. In our work we examined the effects of sanguinarine and chelerythrine on CYP1A1 expression and catalytic activity in human hepatoma cells-HepG2. Sanguinarine and chelerythrine did not affect basal and dioxin-inducible expression of CYP1A1 mRNA and protein in HepG2 cells. The enzymatic activity of CYP1A1 was assessed by the fluorescent measurement of 7-ethyxoresorufin-O-deethylase (EROD) activity. We observed a slight decrease of dioxin-induced EROD activity in HepG2 cells by sanguinarine and chelerythrine. This decrease was attributed to the inhibition of CYP1A1 catalytic activity, as revealed by enzyme kinetic studies on recombinant CYP1A1 protein. The IC50 values for the inhibition of CYP1A1 by sanguinarine and chelerythrine were 2.1 and 1.9muM, respectively. In conclusion, albeit the CYP1A modulates QBA cytotoxicity and genotoxicity, the QBA themselves do not affect CYP1A1 expression. The data indicate that studied alkaloids do not have specific cellular target and their biological effects are rather pleiotropic.

• MeSH
• alkaloidy farmakologie   MeSH
• benzofenantridiny MeSH
• cytochrom P-450 CYP1A1 antagonisté a inhibitory   biosyntéza   MeSH
• cytochrom P-450 CYP1A2 biosyntéza   MeSH
• fenantridiny farmakologie   MeSH
• financování organizované MeSH
• hepatocelulární karcinom enzymologie   MeSH
• inhibitory cytochromu P450 CYP1A2 MeSH
• inhibitory enzymů farmakologie   MeSH
• isochinoliny MeSH
• katalýza MeSH
• lidé MeSH
• messenger RNA biosyntéza   MeSH
• nádorové buněčné linie MeSH
• nádory jater enzymologie   MeSH
• rekombinantní proteiny chemie   MeSH
• Check Tag
• lidé MeSH

Nežádoucí účinky léčiv představují významný klinický problém. Jsou zčásti způsobeny značnou variabilitou lékové odpovědi, která je vyvolána vzájemnou interakcí farmakokinetiky, farmakodynamiky a faktorů onemocnění. Přehled se soustřeďuje na metabolické změny vyvolané polymorfizmemcytochromu P450 a uvádí příklady indukce a inhibice tohoto enzymatického systému při vzniku nežádoucích lékových interakcí. Z klinického hlediska je nutné věnovat pozornost zejména antidiabetikům, antikoagulanciím a fenytoinu. Lze předpokládat, že výskyt nežádoucích účinků léčiv s genetickým polymorfizmem a malou terapeutickou šíří může být snížen pomocí terapeutického monitorování léčiv a terapií individualizovanou na základě genetických poznatků.

Adverse drug reactions represent a common clinical problem. They are partly induced by a large variability in drug response, which results from the complex interplay between pharmacokinetics, pharmacodynamics and other disease-associated factors. The reviewde scribes metabolic changes caused by polymorfism in the cytochrome P450 and gives examples of induction and inhibition of this enzyme system in relation to adverse drug interaction. From the clinical point of view, attention should be paid especially to antidiabetics, anticoagulants and phenytoin. Therapeutic drug monitoring and genetic-based individualization of the therapy with polymorphically metabolized drugs with narrow therapeutic range can contribute to the decreased incidence of adverse drug reactions.

• MeSH
• cytochrom P-450 CYP1A2 metabolismus   MeSH
• cytochrom P-450 CYP2D6 metabolismus   MeSH
• farmakologie MeSH
• inhibitory cytochromu P450 CYP1A2 MeSH
• inhibitory cytochromu P450 CYP2D6 MeSH
• inhibitory cytochromu P450 MeSH
• léčivé přípravky metabolismus   MeSH
• lékové interakce MeSH
• nežádoucí účinky léčiv MeSH
• P-glykoprotein farmakologie   metabolismus   MeSH
• polymorfismus genetický MeSH
• systém (enzymů) cytochromů P-450 metabolismus   MeSH
• Publikační typ
• přehledy MeSH

• MeSH
• alkaloidy farmakokinetika   MeSH
• antifungální látky farmakokinetika   MeSH
• cytochrom P-450 CYP1A1 antagonisté a inhibitory   metabolismus   MeSH
• cytochrom P-450 CYP1A2 metabolismus   MeSH
• enzymová indukce MeSH
• finanční podpora výzkumu jako téma MeSH
• hepatocyty enzymologie   účinky léků   MeSH
• inhibitory cytochromu P450 CYP1A2 MeSH
• inhibitory enzymů MeSH
• krysa rodu rattus MeSH
• zvířata MeSH
• Check Tag
• krysa rodu rattus MeSH
• zvířata MeSH