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Sample records for human p450 cyp1a2

  1. Understanding the Mechanism of Human P450 CYP1A2 Using Coupled Quantum-Classical Simulations in a Dynamical Environment

    Energy Technology Data Exchange (ETDEWEB)

    Draeger, E W; Bennion, B; Gygi, F; Lightstone, F

    2006-02-10

    The reaction mechanism of the human P450 CYP1A2 enzyme plays a fundamental role in understanding the effects of environmental carcinogens and mutagens on humans. Despite extensive experimental research on this enzyme system, key questions regarding its catalytic cycle and oxygen activation mechanism remain unanswered. In order to elucidate the reaction mechanism in human P450, new computational methods are needed to accurately represent this system. To enable us to perform computational simulations of unprecedented accuracy on these systems, we developed a dynamic quantum-classical (QM/MM) hybrid method, in which ab initio molecular dynamics are coupled with classical molecular mechanics. This will provide the accuracy needed to address such a complex, large biological system in a fully dynamic environment. We also present detailed calculations of the P450 active site, including the relative charge transfer between iron porphine and tetraphenyl porphyrin.

  2. Genotype and allele frequencies of polymorphic cytochromes P450 CYP1A2 and CYP2E1 in Mexicans.

    Science.gov (United States)

    Mendoza-Cantú, Ania; Castorena-Torres, Fabiola; Bermudez, Mario; Martínez-Hernández, Roberto; Ortega, Arturo; Salinas, Juan E; Albores, Arnulfo

    2004-01-01

    CYP1A2 and CYP2E1 are two of the main cytochrome P450 isoforms involved in the metabolism of commonly used drugs and xenobiotic compounds considered to be responsible for or possible participants in the development of several human diseases. Individual susceptibility to developing these pathologies relies, among other factors, on genetic polymorphism which depends on ethnic differences, as the frequency of mutant genotypes varies in different human populations. Thus the aim of this study was to investigate the frequency of CYP1A2 5'-flanking region and CYP2E1 Rsa I/Pst I polymorphisms in Mexicans by PCR-RFLP methods. The DNA of 159 subjects was analysed and mutant allele frequencies of 30% for CYP2E1 Rsa I/Pst I sites and 43% for CYP1A2 5'-flanking region were found. These frequencies are higher than those previously reported for other human populations.

  3. Interactions between Cytochromes P450 2B4 (CYP2B4) and 1A2 (CYP1A2) Lead to Alterations in Toluene Disposition and P450 Uncoupling

    Science.gov (United States)

    Reed, James R.; Cawley, George F.; Backes, Wayne L.

    2013-01-01

    The goal of this study was to characterize the effects of CYP1A2•CYP2B4 complex formation on the rates and efficiency of toluene metabolism by comparing the results from simple reconstituted systems containing P450 reductase (CPR) and a single P450 to those using a mixed system containing CPR and both P450s. In the mixed system, the rates of formation of CYP2B4-specific benzyl alcohol and p-cresol were inhibited, whereas that of CYP1A2-specific o-cresol was increased, results consistent with the formation of a CYP1A2•CYP2B4 complex where the CYP1A2 moiety has higher affinity for CPR binding. Comparison of the rates of NADPH oxidation and production of hydrogen peroxide and excess water by the simple and mixed systems indicated that excess water formed at a much lower rate in the mixed system. The commensurate increase in the rate of CYP1A2-specific product formation suggested the P450P450 interaction increased the putative rate-limiting step of CYP1A2 catalysis, abstraction of a hydrogen radical from the substrate. Cumene hydroperoxide-supported metabolism was measured to determine whether the effects of the P450P450 interaction required the presence of CPR. Peroxidative metabolism was not affected by the interaction of the two P450s, even with CPR present. However, CPR did stimulate peroxidative metabolism by the simple system containing CYP1A2. These results suggest the major functional effects of the P450P450 interaction are mediated by changes in the relative abilities of the P450s to receive electrons from CPR. Furthermore, CPR may play an effector role by causing a conformation change in CYP1A2 that makes its metabolism more efficient. PMID:23675771

  4. Caffeine raises the serum melatonin level in healthy subjects: an indication of melatonin metabolism by cytochrome P450(CYP)1A2.

    Science.gov (United States)

    Ursing, C; Wikner, J; Brismar, K; Röjdmark, S

    2003-05-01

    Caffeine is metabolized in the liver by cytochrome P450(CYP)1A2. Recent findings imply that this enzyme may also be of importance for the metabolism of human melatonin (MT). If caffeine and MT are metabolized by the same enzyme, one may expect to find different serum MT levels after ingestion of coffee compared with placebo. Although coffee is consumed by people all over the world, few studies have focused on whether caffeine actually affects serum MT levels in normal subjects. We decided to study that particular topic. For that purpose 12 healthy individuals were tested on two occasions, one week apart. On one of these occasions they were given a capsule containing 200 mg caffeine in the evening. On the other, they received placebo. The experimental order was randomized. Serum MT levels were determined every second hour between 22:00 h and 08:00 h, and the melatonin areas under the curve (MT-AUCs) were calculated. After caffeine the serum MT level rose from 0.09 +/- 0.03 nmol/l at 22:00 h to 0.48 +/- 0.07 nmol/l at 04:00 h. The corresponding rise after placebo was less prominent (from 0.06 +/- 0.01 to 0.35 +/- 0.06 nmol/l). This was reflected by the MT-AUC which was 32% larger after ingestion of caffeine compared with placebo (MT-AUC(caffeine) 3.16 +/- 0.44 nmol/l x h vs MT-AUC(placebo) 2.39 +/- 0.40 nmol/l x h; p < 0.02). These findings imply that caffeine, ingested in the evening at a dose corresponding to two ordinary cups of coffee, augments the nocturnal serum MT level, which in turn supports the notion that cytochrome P450(CYP)1A2 is involved in the hepatic metabolism of human MT.

  5. Caffeine induces CYP1A2 expression in rat hepatocytes but not in human hepatocytes.

    Science.gov (United States)

    Vaynshteyn, David; Jeong, Hyunyoung

    2012-06-01

    Caffeine is the active constituent in coffee. Continual consumption of caffeine can lead to an attenuated response also known as tolerance. Results from rat studies have shown that caffeine is an inducer of CYP1A2, the enzyme responsible for caffeine's metabolism. This suggests that CYP1A2 induction by caffeine may be in part responsible for caffeine tolerance. However, whether caffeine induces CYP1A2 expression in humans remains unknown. Our results from luciferase assays performed in HepG2 cells showed that caffeine is not an activator of the aromatic hydrocarbon receptor (AhR), a major transcription factor involved in upregulation of CYP1A2. Furthermore, caffeine did not induce CYP1A2 expression in primary human hepatocytes at a concentration attained by ordinary coffee drinking. On the other hand, caffeine enhanced CYP1A2 expression by 9-fold in rat hepatocytes. Our results suggest that caffeine from ordinary coffee drinking does not induce CYP1A2 expression in humans and that factors other than CYP1A2 induction by caffeine likely contribute to development of caffeine tolerance in humans.

  6. Caffeine induces CYP1A2 expression in rat hepatocytes but not in human hepatocytes

    OpenAIRE

    Vaynshteyn, David; Jeong, Hyunyoung

    2012-01-01

    Caffeine is the active constituent in coffee. Continual consumption of caffeine can lead to an attenuated response also known as tolerance. Results from rat studies have shown that caffeine is an inducer of CYP1A2, the enzyme responsible for caffeine’s metabolism. This suggests that CYP1A2 induction by caffeine may be in part responsible for caffeine tolerance. However, whether caffeine induces CYP1A2 expression in humans remains unknown. Our results from luciferase assays performed in HepG2 ...

  7. A predominate role of CYP1A2 for the metabolism of nabumetone to the active metabolite, 6-methoxy-2-naphthylacetic acid, in human liver microsomes.

    Science.gov (United States)

    Turpeinen, Miia; Hofmann, Ute; Klein, Kathrin; Mürdter, Thomas; Schwab, Matthias; Zanger, Ulrich M

    2009-05-01

    Nabumetone, a widely used nonsteroidal anti-inflammatory drug, requires biotransformation into 6-methoxy-2-naphthylacetic acid (6-MNA), a close structural analog to naproxen, to achieve its analgesic and anti-inflammatory effects. Despite its wide use, the enzymes involved in metabolism have not been identified. In the present study, several in vitro approaches were used to identify the cytochrome P450 (P450) enzyme(s) responsible for 6-MNA formation. In human liver microsomes (HLMs) 6-MNA formation displayed monophasic Michaelis-Menten kinetics with apparent K(m) and V(max) values (mean +/- S.D.) of 75.1 +/- 15.3 microM and 1304 +/- 226 pmol/min/mg protein, respectively, and formation rate of 6-MNA varied approximately 5.5-fold (179-983 pmol/min/mg protein). 6-MNA activity correlated strongly with both CYP1A2-mediated phenacetin O-deethylation activity and CYP1A2 protein content (r = 0.85 and 0.74, respectively; p nabumetone, 6-MNA, is predominantly catalyzed by CYP1A2 in HLMs with only minor contribution of other P450s.

  8. Polymorphisms in the cytochrome P450 genes CYP1A2, CYP1B1, CYP3A4, CYP3A5, CYP11A1, CYP17A1, CYP19A1 and colorectal cancer risk

    Directory of Open Access Journals (Sweden)

    Withey Laura

    2007-07-01

    Full Text Available Abstract Background Cytochrome P450 (CYP enzymes have the potential to affect colorectal cancer (CRC risk by determining the genotoxic impact of exogenous carcinogens and levels of sex hormones. Methods To investigate if common variants of CYP1A2, CYP1B1, CYP3A4, CYP3A5, CYP11A1, CYP17A1 and CYP19A1 influence CRC risk we genotyped 2,575 CRC cases and 2,707 controls for 20 single nucleotide polymorphisms (SNPs that have not previously been shown to have functional consequence within these genes. Results There was a suggestion of increased risk, albeit insignificant after correction for multiple testing, of CRC for individuals homozygous for CYP1B1 rs162558 and heterozygous for CYP1A2 rs2069522 (odds ratio [OR] = 1.36, 95% confidence interval [CI]: 1.03–1.80 and OR = 1.34, 95% CI: 1.00–1.79 respectively. Conclusion This study provides some support for polymorphic variation in CYP1A2 and CYP1B1 playing a role in CRC susceptibility.

  9. Bioconversion of Mono- and Sesquiterpenoids by Recombinant Human Cytochrome P450 Monooxygenases

    NARCIS (Netherlands)

    Julsing, Mattijs K.; Fichera, Mario A.; Malz, Frank; Ebbelaar, Monique; Bos, Rein; Woerdenbag, Herman J.; Quax, Wim J.; Kayser, Oliver

    2008-01-01

    Cytochrome P450 monooxygenases play an important role in the biosynthesis and metabolism of terpenoids. We explored the potential of recombinant human liver cytochrome P450 monooxygenases CYP1A2, CYP2C9, and CYP3A4, heterologously expressed in Escherichia coli, to convert mono- and sesquiterpenoids

  10. Changes in CYP1A2 activity in humans after 3,4-methylenedioxymethamphetamine (MDMA, ecstasy) administration using caffeine as a probe drug.

    Science.gov (United States)

    Yubero-Lahoz, Samanta; Pardo, Ricardo; Farre, Magí; Mathuna, Brian Ó; Torrens, Marta; Mustata, Cristina; Perez-Mañá, Clara; Langohr, Klaus; Carbó, Marcel Lí; de la Torre, Rafael

    2012-01-01

    3,4-Methylenedioxymethamphetamine (MDMA; ecstasy) is a ring-substituted amphetamine widely used for recreational purposes. MDMA is predominantly O-demethylenated in humans by cytochrome P450 (CYP) 2D6, and is also a potent mechanism-based inhibitor of the enzyme. After assessing the inhibition and recovery of CYP2D6 in a previous study, the aim of this work was to study in humans the activity of CYP1A2 in vivo after CYP2D6 had been inhibited by MDMA, using caffeine as a probe drug. Twelve male and nine female recreational MDMA users were included. In session 1, 100 mg of caffeine was given at 0 h. In session 2, a 1.5 mg/kg MDMA dose (range 75-100 mg) was given at 0 h followed by a 100 mg dose of caffeine 4 h later. Aliquots of plasma were assayed for caffeine (137X) and paraxanthine (17X) and statistically significant differences were assessed with a one-way ANOVA. There were significant gender differences at basal condition, which persisted after MDMA administration. CYP1A2 activity was higher in both genders after drug administration, with an increase in 40% in females and 20% in males. Results show an increase in CYP1A2 activity when CYP2D6 is inhibited by MDMA in both genders, being more pronounced in females.

  11. Inhibition of human cytochrome P450 enzymes by the natural hepatotoxin safrole.

    Science.gov (United States)

    Ueng, Yune-Fang; Hsieh, Chih-Hang; Don, Ming-Jaw

    2005-05-01

    The hepatotoxin, safrole is a methylenedioxy phenyl compound, found in sassafras oil and certain other essential oils. Recombinant cytochrome P450 (CYP, P450) and human liver microsomes were studied to investigate the selective inhibitory effects of safrole on human P450 enzymes and the mechanisms of action. Using Escherichia coli-expressed human P450, our results demonstrated that safrole was a non-selective inhibitor of CYP1A2, CYP2A6, CYP2D6, CYP2E1, and CYP3A4 in the IC(50) order CYP2E1 Safrole strongly inhibited CYP1A2, CYP2A6, and CYP2E1 activities with IC(50) values less than 20 microM. Safrole caused competitive, non-competitive, and non-competitive inhibition of CYP1A2, CYP2A6 and CYP2E1 activities, respectively. The inhibitor constants were in the order CYP1A2 safrole strongly inhibited 7-ethoxyresorufin O-deethylation, coumarin hydroxylation, and chlorzoxazone hydroxylation activities. These results revealed that safrole was a potent inhibitor of human CYP1A2, CYP2A6, and CYP2E1. With relatively less potency, CYP2D6 and CYP3A4 were also inhibited.

  12. Analysis of caffeine and paraxanthine in human saliva with ultra-high-performance liquid chromatography for CYP1A2 phenotyping.

    Science.gov (United States)

    Jordan, Nan Yeun; Mimpen, Jolet Y; van den Bogaard, Willie J M; Flesch, Frits M; van de Meent, Michiel H M; Torano, Javier Sastre

    2015-07-15

    Cytochrome P450 1A2 (CYP1A2) plays an important role in drug metabolism. Caffeine (CAF) is converted into paraxanthine (PX) by this enzyme and is used as a xenobiotic substrate to determine the CYP1A2 phenotype in humans. A method for the quantification of CAF and PX in saliva was developed using liquid-liquid extraction with ethyl acetate and analysis with ultra-high-performance liquid chromatography. Peaks from CAF, PX and internal standard were resolved within 6min. The method was validated from 0.05 to 5μgmL(-1) CAF and 0.025-2.5μgmL(-1) PX. Inter- and intra-day accuracies ranged from 91.2 to 107.2% with precisions concentration ratios from volunteers were 0.26-1.09 with mean ratios of 0.78±0.26 and 0.38±0.10 for regular and light/non-coffee drinkers, respectively.

  13. In vitro metabolism of genistein and tangeretin by human and murine cytochrome p450s

    DEFF Research Database (Denmark)

    Breinholt, Vibeke; Rasmussen, Salka; Brøsen, Kim

    2003-01-01

    Recombinant cytochrome P450 (CYP) 1A2, 3A4, 2C9 or 2D6 enzymes obtained from Escherichia coli and human liver microsomes samples were used to investigate the ability of human CYP enzymes to metabolize the two dietary flavonoids, genistein and tangeretin. Analysis of the metabolic profile from...

  14. Enantioselective metabolism of the endocrine disruptor pesticide methoxychlor by human cytochromes P450 (P450s): major differences in selective enantiomer formation by various P450 isoforms.

    Science.gov (United States)

    Hu, Yiding; Kupfer, David

    2002-12-01

    Methoxychlor, a currently used pesticide that in mammals elicits proestrogenic/estrogenic activity and reproductive toxicity, has been classified as a prototype endocrine disruptor. Methoxychlor is prochiral, and its metabolites 1,1,1-trichloro-2-(4-hydroxyphenyl)-2-(4-methoxyphenyl)ethane (mono-OH-M); 1,1,1-trichloro- 2-(4-methoxyphenyl)-2-(3, 4-dihydroxyphenyl)ethane (catechol-M); and 1,1,1-trichloro-2-(4-hydroxyphenyl)-2-(3, 4-dihydroxyphenyl)ethane (tris-OH-M) are chiral; whereas 1,1,1-trichloro-2, 2-bis(4-hydroxyphenyl)ethane (bis-OH-M) is achiral. These metabolites are formed during methoxychlor incubation with liver microsomes or recombinant cytochrome p450s (rp450s). Since methoxychlor-metabolite enantiomers may have different estrogenic/antiestrogenic/antiandrogenic activities than corresponding racemates, the possibility that p450s preferentially generate or use R or S enantiomers, was examined. Indeed, rCYP1A2 and r2A6 mono-demethylated methoxychlor primarily into (R)-mono-OH-M at 91 and 75%, respectively, whereas rCYP1A1, 2B6, 2C8, 2C9, 2C19, and 2D6 formed the (S)-enantiomer at 69, 66, 75, 95, 96, and 80%, respectively. However, rCYP3A4, 3A5, and 2B1(rat) weakly demethylated methoxychlor without enantioselectivity. Human liver microsomes generated (S)-mono-OH-M (77-87%), suggesting that CYP1A2 and 2A6 display only minor catalytic contribution. P450 inhibitors demonstrated that CYP2C9 and possibly 2C19 are major hepatic catalysts forming (S)-mono-OH-M, and CYP1A2 is primarily involved in forming the (R)-mono-OH-M. Demethylation rate of (S)-mono-OH-M versus (R)-mono-OH-M forming achiral bis-OH-M by rCYP1A2 was 97/3, compared with 15/85 and 17/83 for rCYP2C9 and 2C19, respectively, indicating opposite substrate enantioselectivity of rCYP1A2 versus 2C9 and 2C19. Also, rCYP1A2 preferentially O-demethylated (R)-catechol-M into (R)-tris-OH-M (at 80%), contrasting r2C9 and r2C19 that yielded (S)-tris-OH-M at 80 and 77%, respectively. Ortho-hydroxylation of

  15. Paracetamol-induced spindle disturbances in V79 cells with and without expression of human CYP1A2

    DEFF Research Database (Denmark)

    Jensen, K G; Poulsen, H E; Doehmer, J

    1996-01-01

    Spindle disturbing effects in terms of c-mitosis and cytotoxicity of paracetamol were investigated in two Chinese hamster V79 cell lines, one of which (V79MZh1A2) was transfected with human CYP1A2. This enzyme catalyses the oxidative formation of the reactive paracetamol metabolite, NAPQI, believed...... to initiate hepatoxicity by covalent binding to proteins after overdose. In the native V79 cell line paracetamol increased c-mitosis frequency in a concentration dependent manner from 8.7 + or - 3.5% (control) to 66 + or - 18% at 20 mM. A significant increase to 13.3 + or - 3.5% was first seen at 2.5 m......M in the native cell line (Pparacetamol. At 5 mM paracetamol the c-mitosis frequency was 14.4 + or - 5.0% and 19.0 + or - 3...

  16. Short-term fasting alters cytochrome P450-mediated drug metabolism in humans.

    Science.gov (United States)

    Lammers, Laureen A; Achterbergh, Roos; de Vries, Emmely M; van Nierop, F Samuel; Klümpen, Heinz-Josef; Soeters, Maarten R; Boelen, Anita; Romijn, Johannes A; Mathôt, Ron A A

    2015-06-01

    Experimental studies indicate that short-term fasting alters drug metabolism. However, the effects of short-term fasting on drug metabolism in humans need further investigation. Therefore, the aim of this study was to evaluate the effects of short-term fasting (36 h) on P450-mediated drug metabolism. In a randomized crossover study design, nine healthy subjects ingested a cocktail consisting of five P450-specific probe drugs [caffeine (CYP1A2), S-warfarin (CYP2C9), omeprazole (CYP2C19), metoprolol (CYP2D6), and midazolam (CYP3A4)] on two occasions (control study after an overnight fast and after 36 h of fasting). Blood samples were drawn for pharmacokinetic analysis using nonlinear mixed effects modeling. In addition, we studied in Wistar rats the effects of short-term fasting on hepatic mRNA expression of P450 isoforms corresponding with the five studied P450 enzymes in humans. In the healthy subjects, short-term fasting increased oral caffeine clearance by 20% (P = 0.03) and decreased oral S-warfarin clearance by 25% (P fasting increased mRNA expression of the orthologs of human CYP1A2, CYP2C19, CYP2D6, and CYP3A4 (P fasting alters cytochrome P450-mediated drug metabolism in a nonuniform pattern. Therefore, short-term fasting is another factor affecting cytochrome P450-mediated drug metabolism in humans.

  17. Inhibition of Cytochrome P450 by Propolis in Human Liver Microsomes.

    Science.gov (United States)

    Ryu, Chang Seon; Oh, Soo Jin; Oh, Jung Min; Lee, Ji-Yoon; Lee, Sang Yoon; Chae, Jung-Woo; Kwon, Kwang-Il; Kim, Sang Kyum

    2016-07-01

    Although propolis is one of the most popular functional foods for human health, there have been no comprehensive studies of herb-drug interactions through cytochrome P450 (CYP) inhibition. The purpose of this study was to determine the inhibitory effects of propolis on the activities of CYP1A2, 2A6, 2B6, 2C9, 2C19, 2D6, 2E1 and 3A4 using pooled human liver microsomes (HLMs). Propolis inhibited CYP1A2, CYP2E1 and CYP2C19 with an IC50 value of 6.9, 16.8, and 43.1 μg/mL, respectively, whereas CYP2A6, 2B6, 2C9, 2D6, and 3A4 were unaffected. Based on half-maximal inhibitory concentration shifts between microsomes incubated with and without nicotinamide adenine dinucleotide phosphate, propolis-induced CYP1A2, CYP2C19, and CYP2E1 inhibition was metabolism-independent. To evaluate the interaction potential between propolis and therapeutic drugs, the effects of propolis on metabolism of duloxetine, a serotonin-norepinephrine reuptake inhibitor, were determined in HLMs. CYP1A2 and CYP2D6 are involved in hydroxylation of duloxetine to 4-hydroxy duloxetine, the major metabolite, which was decreased following propolis addition in HLMs. These results raise the possibility of interactions between propolis and therapeutic drugs metabolized by CYP1A2.

  18. Metabolism of sesamin by cytochrome P450 in human liver microsomes.

    Science.gov (United States)

    Yasuda, Kaori; Ikushiro, Shinichi; Kamakura, Masaki; Ohta, Miho; Sakaki, Toshiyuki

    2010-12-01

    Metabolism of sesamin by cytochrome P450 (P450) was examined using yeast expression system and human liver microsomes. Saccharomyces cerevisiae cells expressing each of human P450 isoforms (CYP1A1, 1A2, 2A6, 2B6, 2C8, 2C9, 2C18, 2C19, 2D6, 2E1, and 3A4) were cultivated with sesamin, and monocatechol metabolite was observed in most of P450s. Kinetic analysis using the microsomal fractions of the recombinant S. cerevisiae cells revealed that CYP2C19 had the largest k(cat)/K(m) value. Based on the kinetic data and average contents of the P450 isoforms in the human liver, the putative contribution of P450s for sesamin metabolism was large in the order of CYP2C9, 1A2, 2C19, and 2D6. A good correlation was observed between sesamin catecholization activity and CYP2C9-specific activity in in vitro studies using 10 individual human liver microsomes, strongly suggesting that CYP2C9 is the most important P450 isoform for sesamin catecholization in human liver. Inhibition studies using each anti-P450 isoform-specific antibody confirmed that CYP2C9 was the most important, and the secondary most important P450 was CYP1A2. We also examined the inhibitory effect of sesamin for P450 isoform-specific activities and found a mechanism-based inhibition of CYP2C9 by sesamin. In contrast, no mechanism-based inhibition by sesamin was observed in CYP1A2-specific activity. Our findings strongly suggest that further studies are needed to reveal the interaction between sesamin and therapeutic drugs mainly metabolized by CYP2C9.

  19. Characterization of human cytochrome P450 enzymes involved in the metabolism of cyamemazine.

    Science.gov (United States)

    Arbus, Christophe; Benyamina, Amine; Llorca, Pierre-Michel; Baylé, Franck; Bromet, Norbert; Massiere, Frédéric; Garay, Ricardo P; Hameg, Ahcène

    2007-12-01

    Recombinant human liver microsomal enzymes of the cytochrome P450 family (CYP1A2, CYP2A6, CYP3A4, CYP2B6, CYP2C8, CYP2C9, CYP2C19, CYP2D6, CYP2E1) were used to determine the metabolic fate of the antipsychotic anxiolytic agent cyamemazine. An LC/MS-MS tandem methodology was developed specifically for identifying the presence of cyamemazine and its metabolites in reaction media. All P450 enzymes investigated, with the exception of CYP2A6 and CYP2E1, degraded cyamemazine, albeit to a different extent, with CYP1A2, CYP2C8 and CYP2C19 being the most efficient (>80%). However, in microsomes prepared from native human hepatocytes, only relatively specific competitors (inhibitors and/or substrates) of CYP1A2, CYP2C8, CYP2C9 and CYP3A4 reduced notably the degradation cyamemazine. The main routes of cyamemazine biotransformation are N-mono-demethylation (CYP1A2, CYP3A4 and CYP2C8) and mono-oxidation (either S-oxidized or hydroxylated derivatives which could not be discriminated because characterized by the same mass value) by CYP1A2 and CYP2C9. Secondary metabolic routes yields N,N-di-demethylated and N-demethylated mono-oxidized products. Thus, under in vitro conditions, cyamemazine is extensively degraded by at least four distinct P450 enzymes, into two primary hydrophilic metabolites. These results suggest that cyamemazine detoxification process is unlikely to be significantly impaired by co-administration of therapeutic agents that are substrates of the CYP metabolic system.

  20. Human hepatic cytochrome P450-specific metabolism of the organophosphorus pesticides methyl parathion and diazinon.

    Science.gov (United States)

    Ellison, Corie A; Tian, Yuan; Knaak, James B; Kostyniak, Paul J; Olson, James R

    2012-01-01

    Organophosphorus pesticides (OPs) are a public health concern due to their worldwide use and documented human exposures. Phosphorothioate OPs are metabolized by cytochrome P450s (P450s) through either a dearylation reaction to form an inactive metabolite, or through a desulfuration reaction to form an active oxon metabolite, which is a potent cholinesterase inhibitor. This study investigated the rate of desulfuration (activation) and dearylation (detoxification) of methyl parathion and diazinon in human liver microsomes. In addition, recombinant human P450s were used to determine the P450-specific kinetic parameters (K(m) and V(max)) for each compound for future use in refining human physiologically based pharmacokinetic/pharmacodynamic (PBPK/PD) models of OP exposure. The primary enzymes involved in bioactivation of methyl parathion were CYP2B6 (K(m) = 1.25 μM; V(max) = 9.78 nmol · min(-1) · nmol P450(-1)), CYP2C19 (K(m) = 1.03 μM; V(max) = 4.67 nmol · min(-1) · nmol P450(-1)), and CYP1A2 (K(m) = 1.96 μM; V(max) = 5.14 nmol · min(-1) · nmol P450(-1)), and the bioactivation of diazinon was mediated primarily by CYP1A1 (K(m) = 3.05 μM; V(max) = 2.35 nmol · min(-1) · nmol P450(-1)), CYP2C19 (K(m) = 7.74 μM; V(max) = 4.14 nmol · min(-1) · nmol P450(-1)), and CYP2B6 (K(m) = 14.83 μM; V(max) = 5.44 nmol · min(-1) · nmol P450(-1)). P450-mediated detoxification of methyl parathion only occurred to a limited extent with CYP1A2 (K(m) = 16.8 μM; V(max) = 1.38 nmol · min(-1) · nmol P450(-1)) and 3A4 (K(m) = 104 μM; V(max) = 5.15 nmol · min(-1) · nmol P450(-1)), whereas the major enzyme involved in diazinon detoxification was CYP2C19 (K(m) = 5.04 μM; V(max) = 5.58 nmol · min(-1) · nmol P450(-1)). The OP- and P450-specific kinetic values will be helpful for future use in refining human PBPK/PD models of OP exposure.

  1. Metabolic activation of o-phenylphenol to a major cytotoxic metabolite, phenylhydroquinone: role of human CYP1A2 and rat CYP2C11/CYP2E1.

    Science.gov (United States)

    Ozawa, S; Ohta, K; Miyajima, A; Kurebayashi, H; Sunouchi, M; Shimizu, M; Murayama, N; Matsumoto, Y; Fukuoka, M; Ohno, Y

    2000-10-01

    1. The in vitro metabolic activation of o-phenylphenol has been evaluated as yielding a toxic metabolite, 2,5-dihydroxybiphenyl (phenylhydroquinone), by p-hydroxylation in liver microsomes of rat and human. The involvement of rat CYP2C11, CYP2E1 and human CYP1A2 in the p-hydroxylation of o-phenylphenol is suggested. 2. 2,3- and phenylhydroquinone, which induced DNA single-strand scission in the presence of 1 microM CuCl2, were the most cytotoxic chemicals examined to cultured mammalian cell lines among o-phenylphenol, m-phenylphenol, p-phenylphenol, 2,2'-, 4,4'-, 2,3- and phenylhydroquinone. 3. Rat and human liver microsomes catalysed the formation of phenylhydroquinone, but not 2,3-dihydroxybiphenyl, using o-phenylphenol as a substrate. A higher rate of metabolic activation of o-phenylphenol was observed with livers of the male than the female rats by 5.6- and 2.6-fold respectively. 4. Inhibitory antibodies against the male-specific CYP2C11 inhibited hepatic o-phenylphenol p-hydroxylation in the male F344 and Sprague-Dawley rat by > 70%. Liver microsomes from the isoniazid-treated rats produced 1.8- and 3-fold induction of o-phenylphenol p-hydroxylation and chlorzoxazone 6-hydroxylation (a CYP2E1-dependent activity) respectively. 5. Human CYP1A2, expressed by baculovirus-mediated cDNA expression systems, exhibited a remarkably higher capacity for o-phenylphenol p-hydroxylation at concentrations of 5 (> 5-fold), 50 (> 2-fold) and 500 microM (> 2-fold) than CYP2A, CYP2B, CYP2Cs, CYP2D6, CYP2E1 and CYP3A4 on the basis of pmol P450. 6. Among various CYP inhibitors tested here, 7,8-benzoflavone and furafylline, typical human CYP1A2 inhibitors, inhibited the microsomal p-hydroxylation of o-phenylphenol in human livers most potently by 70 and 50% respectively. 7. The results thus indicate the involvement of rat CYP2C11/CYP2E1 and human CYP1A2 in the hepatic p-hydroxylation of o-phenylphenol.

  2. Effects of Eupatilin and Jaceosidin on Cytochrome P450 Enzyme Activities in Human Liver Microsomes

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    Ji Hyun Jeong

    2010-09-01

    Full Text Available Eupatilin and jaceosidin are bioactive flavones found in the medicinal herbs of the genus Artemisia. These bioactive flavones exhibit various antioxidant, antiinflammatory, antiallergic, and antitumor activities. The inhibitory potentials of eupatilin and jaceosidin on the activities of seven major human cytochrome P450 enzymes in human liver microsomes were investigated using a cocktail probe assay. Eupatilin and jaceosidin potently inhibited CYP1A2-catalyzed phenacetin O-deethylation with 50% inhibitory concentration (IC50 values of 9.4 mM and 5.3 mM, respectively, and CYP2C9-catalyzed diclofenac 4-hydroxylation with IC50 values of 4.1 mM and 10.2 mM, respectively. Eupatilin and jaceosidin were also found to moderately inhibit CYP2C19-catalyzed [S]-mephenytoin 4¢-hydroxylation, CYP2D6-catalyzed bufuralol 1¢-hydroxylation, and CYP2C8-catalyzed amodiaquine N-deethylation. Kinetic analysis of human liver microsomes showed that eupatilin is a competitive inhibitor of CYP1A2 with a Ki value of 2.3 mM and a mixed-type inhibitor of CYP2C9 with a Ki value of 1.6 mM. Jaceosidin was shown to be a competitive inhibitor of CYP1A2 with a Ki value of 3.8 mM and a mixed-type inhibitor of CYP2C9 with Ki value of 6.4 mM in human liver microsomes. These in vitro results suggest that eupatilin and jaceosidin should be further examined for potential pharmacokinetic drug interactions in vivo due to inhibition of CYP1A2 and CYP2C9.

  3. Metabolism of sanguinarine in human and in rat: characterization of oxidative metabolites produced by human CYP1A1 and CYP1A2 and rat liver microsomes using liquid chromatography-tandem mass spectrometry.

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    Deroussent, Alain; Ré, Micheline; Hoellinger, Henri; Cresteil, Thierry

    2010-07-08

    The quaternary benzo[c]phenanthridine alkaloid, sanguinarine (SA), has been detected in the mustard oil contaminated with Argemone mexicana, which produced severe human intoxications during epidemic dropsy in India. Today, SA metabolism in human and in rat has not yet been fully elucidated. The goal of this study is to investigate the oxidative metabolites of SA formed during incubations with rat liver microsomes (RLM) and recombinant human cytochrome P450 (CYP) and to tentatively identify the CYP isoforms involved in SA detoxification. Metabolites were analyzed by liquid chromatography combined with electrospray ionization-tandem mass spectrometry. Up to six metabolites were formed by RLM and their modified structure has been proposed using their mass spectra and mass shifts from SA (m/z 332). The main metabolite M2 (m/z 320) resulted from ring-cleavage of SA followed by demethylation, whereas M4 (m/z 348) is oxidized by CYP in the presence of NADPH. The diol-sanguinarine metabolite M6 (m/z 366) formed by RLM might derive from a putative epoxy-sanguinarine metabolite M5 (m/z 348). M4 and M6 could be detected in rat urine as their respective glucuronides. 5,6-Dihydrosanguinarine is the prominent derivative formed from SA in cells expressing no CYP. Oxidative biotransformation of SA was investigated using eight human CYPs: only CYP1A1 and CYP1A2 displayed activity.

  4. CYP1A2-mediated biotransformation of cardioactive 2-thienylidene-3,4-methylenedioxybenzoylhydrazine (LASSBio-294) by rat liver microsomes and human recombinant CYP enzymes.

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    Fraga, Aline Guerra M; da Silva, Leandro Louback; Fraga, Carlos Alberto Manssour; Barreiro, Eliezer J

    2011-01-01

    We describe herein the metabolic fate of cardioactive 1,3-benzodioxolyl N-acylhydrazone prototype LASSBio-294 (4) and the structural identification of its major phase I metabolite from rat liver microsomal assays. Our results confirmed the hard-metabolic character of N-acylhydrazone (NAH) framework of LASSBio-294 (4). The development of a reproducible analytical methodology for the major metabolite by using HPLC-MS and the comparison with an authentic synthetic sample, allowed us to identify 2-thienylidene 3,4-dihydroxybenzoylhydrazine derivative (7), formed by oxidative scission of methylenedioxy bridge of LASSBio-294, as the main metabolite formed by action of CYP1A2 isoform. The identification of this isoform in the LASSBio-294 in the clearance of LASSBio-294 (4) oxidation was performed by the use of selective CYP inhibitors or human recombinant CYP enzymes.

  5. Inhibition selectivity of grapefruit juice components on human cytochromes P450.

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    Tassaneeyakul, W; Guo, L Q; Fukuda, K; Ohta, T; Yamazoe, Y

    2000-06-15

    Five compounds including furanocoumarin monomers (bergamottin, 6', 7'-dihydroxybergamottin (DHB)), furanocoumarin dimers (4-¿¿6-hydroxy-71-¿(1-hydroxy-1-methyl)ethyl-4-methyl-6-(7-oxo-7H- furo¿3,2-g1benzopyran-4-yl)-4-hexenyl]oxy]-3,7-dimethyl- 2-octenyl]oxy]-7H-furo[3,2-g]¿1benzopyran-7-one (GF-I-1) and 4-¿¿6-hydroxy-7¿¿4-methyl-1-(1-methylethenyl)-6-(7-oxo-7H-furo¿3, 2-g1benzopyran-4-yl)-4-hexenylŏxy-3, 7-dimethyl-2-octenylŏxy-7H-furo¿3,2-g1benzopyran-7-one (GF-I-4)), and a sesquiterpene nootkatone have been isolated from grapefruit juice and screened for their inhibitory effects toward human cytochrome P450 (P450) forms using selective substrate probes. Addition of ethyl acetate extract of grapefruit juice into an incubation mixture resulted in decreased activities of CYP3A4, CYP1A2, CYP2C9, and CYP2D6. All four furanocoumarins clearly inhibited CYP3A4-catalyzed nifedipine oxidation in concentration- and time-dependent manners, suggesting that these compounds are mechanism-based inhibitors of CYP3A4. Of the furanocoumarins investigated, furanocoumarin dimers, GF-I-1 and GF-I-4, were the most potent inhibitors of CYP3A4. Inhibitor concentration required for half-maximal rate of inactivation (K(I)) values for bergamottin, DHB, GF-I-1, and GF-I-4 were calculated, respectively, as 40.00, 5. 56, 0.31, and 0.13 microM, whereas similar values were observed on their inactivation rate constant at infinite concentration of inhibitor (k(inact), 0.05-0.08 min(-1)). Apparent selectivity toward CYP3A4 does occur with the furanocoumarin dimers. In contrast, bergamottin showed rather stronger inhibitory effect on CYP1A2, CYP2C9, CYP2C19, and CYP2D6 than on CYP3A4. DHB inhibited CYP3A4 and CYP1A2 activities at nearly equivalent potencies. Among P450 forms investigated, CYP2E1 was the least sensitive to the inhibitory effect of furanocoumarin components. A sesquiterpene nootkatone has no significant effect on P450 activities investigated except for CYP2A6 and CYP2C19

  6. Metabolism of 7-benzyloxy-4-trifluoromethyl-coumarin by human hepatic cytochrome P450 isoforms.

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    Renwick, A B; Surry, D; Price, R J; Lake, B G; Evans, D C

    2000-10-01

    1. The metabolism of 7-benzyloxy-4-trifluoromethylcoumarin (BFC) to 7-hydroxy-4-trifluoromethylcoumarin (HFC) was studied in human liver microsomal preparations and in cDNA-expressed human cytochrome P450 (CYP) isoforms. 2. Kinetic analysis of the NADPH-dependent metabolism of BFC to HFC in four preparations of pooled human liver microsomes revealed mean (+/- SEM) Km and Vmax of 8.3 +/- 1.3 microM and 454 +/- 98 pmol/min/mg protein respectively. 3. The metabolism of BFC to HFC was determined in a characterized bank of 24 individual human liver microsomal preparations employing BFC substrate concentrations of 20 and 50 microM (i.e. about two and six times Km respectively). With 20 microM BFC the highest correlations were observed between BFC metabolism and markers of CYP1A2 (r2 = 0.784-0.797) and then with CYP3A (r2 = 0.434-0.547) isoforms, whereas with 50 microM BFC the highest correlations were observed between BFC metabolism and markers of CYP3A (r2 = 0.679-0.837) and then with CYP1A2 (r2 = 0.421-0.427) isoforms. At both BFC substrate concentrations, lower correlations were observed between BFC metabolism and enzymatic markers for CYP2A6, CYP2B6, CYP2C9, CYP2C19, CYP2D6, CYP2E1 and CYP4A9/11. 4. Using human beta-lymphoblastoid cell microsomes containing cDNA-expressed CYP isoforms, 20 microM BFC was metabolized by CYP1A2 and CYP3A4, with lower rates of metabolism being observed with CYP2C9 and CYP2C19. Kinetic studies with the CYP1A2 and CYP3A4 preparations demonstrated a lower Km with the CYP1A2 preparation, but a higher Vmax with the CYP3A4 preparation. 5. The metabolism of 20 microM BFC in human liver microsomes was inhibited to 37-48% of control by 5-100 microM of the mechanism-based CYP1A2 inhibitor furafylline and to 64-69% of control by 5-100 microM of the mechanism-based CYP3A4 inhibitor troleandomycin. While some inhibition of BFC metabolism was observed in the presence of 100 and 200 microM diethyldithiocarbamate, the addition of 2-50 micro

  7. Inhibition of Human Cytochrome P450 Enzymes by Allergen Removed Rhus verniciflua Stoke Standardized Extract and Constituents

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    Hyunsik Jung

    2014-01-01

    Full Text Available Objective. Potential interactions between herbal extracts and the cytochrome P450 (CYP system lead to serious adverse events or decreased drug efficacy. Rhus verniciflua stoke (RVS and its constituents have been reported to have various pharmacological properties. We evaluated the inhibitory potential of RVS and its constituents on the major CYP isoforms. Methods. The effects of allergen removed RVS (aRVS standardized extract and major components, fustin and fisetin isolated from aRVS, were evaluated on CYP1A2, CYP2C9, CYP2C19, CYP2D6, and CYP3A4 isoenzyme activity by a luminescent CYP recombinant human enzyme assay. Results. The aRVS extract showed relative potent inhibitory effects on the CYP2C9 (IC50, <0.001 μg/mL, CYP2C19 (IC50, 9.68 μg/mL, and CYP1A2 (IC50, 10.0 μg/mL. However, it showed weak inhibition on CYP3A4 and CYP2D6. Fustin showed moderate inhibitory effects on the CYP2C19 (IC50, 64.3 μg/mL and weak inhibition of the other CYP isoforms similar to aRVS. Fisetin showed potent inhibitory effects on CYP2C9, CYP2C19, and CYP1A2. Fisetin showed moderate inhibition of CYP2D6 and weak inhibition of CYP3A4. Conclusions. These results indicate that aRVS, a clinically available herbal medicine, could contribute to herb-drug interactions when orally coadministered with drugs metabolized by CYP2C9, CYP2C19, and CYP1A2.

  8. 10-(6'-Plastoquinonyl)decyltriphenylphosphonium (SkQ1) Does Not Increase the Level of Cytochromes P450 in Rat Liver and Human Hepatocyte Cell Culture.

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    Myasoedova, K N; Silachev, D N; Petrov, A D

    2016-12-01

    Mitochondria-targeted antioxidant SkQ1 did not increase the content of cytochromes P450 in livers of rats that were given SkQ1 in drinking water for 5 days in a dose (2.5 µmol per kg body weight) that exceeded 10 times the SkQ1 therapeutic dose. SkQ1 did not affect the levels of cytochrome P450 forms CYP1A2, CYP2B6, and CYP3A4 in monolayer cultures of freshly isolated human hepatocytes, while specific inducers of these forms (omeprazole, phenobarbital, and rifampicin, respectively) significantly increased expression of the cytochromes P450 under the same conditions. We conclude that therapeutic doses of SkQ1 do not induce cytochromes P450 in liver, and the absence of the inducing effect cannot be explained by poor availability of hepatocytes to SkQ1 in vivo.

  9. Metabolism of (-)-cis- and (-)-trans-rose oxide by cytochrome P450 enzymes in human liver microsomes.

    Science.gov (United States)

    Nakahashi, Hiroshi; Yamamura, Yuuki; Usami, Atsushi; Rangsunvigit, Pramoch; Malakul, Pomthong; Miyazawa, Mitsuo

    2015-12-01

    The in vitro metabolism of (-)-cis- and (-)-trans-rose oxide was investigated using human liver microsomes and recombinant cytochrome P450 (P450 or CYP) enzymes for the first time. Both isomers of rose oxide were incubated with human liver microsomes, and the formation of the respective 9-oxidized metabolite were determined using gas chromatography-mass spectrometry (GC-MS). Of 11 different recombinant human P450 enzymes used, CYP2B6 and CYP2C19 were the primary enzymes catalysing the metabolism of (-)-cis- and (-)-trans-rose oxide. CYP1A2 also efficiently oxidized (-)-cis-rose oxide at the 9-position but not (-)-trans-rose oxide. α-Naphthoflavone (a selective CYP1A2 inhibitor), thioTEPA (a CYP2B6 inhibitor) and anti-CYP2B6 antibody inhibited (-)-cis-rose oxide 9-hydroxylation catalysed by human liver microsomes. On the other hand, the metabolism of (-)-trans-rose oxide was suppressed by thioTEPA and anti-CYP2B6 at a significant level in human liver microsomes. However, omeprazole (a CYP2C19 inhibitor) had no significant effects on the metabolism of both isomers of rose oxide. Using microsomal preparations from nine different human liver samples, (-)-9-hydroxy-cis- and (-)-9-hydroxy-trans-rose oxide formations correlated with (S)-mephenytoin N-demethylase activity (CYP2B6 marker activity). These results suggest that CYP2B6 plays important roles in the metabolism of (-)-cis- and (-)-trans-rose oxide in human liver microsomes.

  10. Differential selectivity of cytochrome P450 inhibitors against probe substrates in human and rat liver microsomes

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    Eagling, Victoria A; Tjia, John F; Back, David J

    1998-01-01

    Aims Chemical inhibitors of cytochrome P450 (CYP) are a useful tool in defining the role of individual CYPs involved in drug metabolism. The aim of the present study was to evaluate the selectivity and rank the order of potency of a range of isoform-selective CYP inhibitors and to compare directly the effects of these inhibitors in human and rat hepatic microsomes. Methods Four chemical inhibitors of human cytochrome P450 isoforms, furafylline (CYP1A2), sulphaphenazole (CYP2C9), diethyldithiocarbamate (CYP2E1), and ketoconazole (CYP3A4) were screened for their inhibitory specificity towards CYP-mediated reactions in both human and rat liver microsomal preparations. Phenacetin O-deethylation, tolbutamide 4-hydroxylation, chlorzoxazone 6-hydroxylation and testosterone 6β-hydroxylation were monitored for enzyme activity. Results Furafylline was a potent, selective inhibitor of phenacetin O-deethylation (CYP1A2-mediated) in human liver microsomes (IC50 = 0.48 μm), but inhibited both phenacetin O-deethylation and tolbutamide 4-hydroxylation (CYP2C9-mediated) at equimolar concentrations in rat liver microsomes (IC50 = 20.8 and 24.0 μm respectively). Sulphaphenazole demonstrated selective inhibition of tolbutamide hydroxylation in human liver microsomes but failed to inhibit this reaction in rat liver microsomes. DDC demonstrated a low level of selectivity as an inhibitory probe for chlorzoxazone 6-hydroxylation (CYP2E1-mediated). DDC also inhibited testosterone 6β-hydroxylation (CYP3A-mediated) in man and rat, and tolbutamide 4-hydroxylase activity in rat. Ketoconazole was a very potent, selective inhibitor of CYP3A4 activity in human liver (IC50 = 0.04 μm). Although inhibiting CYP3A in rat liver it also inhibited all other reactions at concentrations ≤5 μm. Conclusions It is evident that CYP inhibitors do not exhibit the same selectivity in human and rat liver microsomes. This is due to differential selectivity of the inhibitors and/or differences in the CYP

  11. Inhibition of human cytochrome P450 enzymes by Bacopa monnieri standardized extract and constituents.

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    Ramasamy, Seetha; Kiew, Lik Voon; Chung, Lip Yong

    2014-02-24

    Bacopa monnieri and the constituents of this plant, especially bacosides, possess various neuropharmacological properties. Like drugs, some herbal extracts and the constituents of their extracts alter cytochrome P450 (CYP) enzymes, causing potential herb-drug interactions. The effects of Bacopa monnieri standardized extract and the bacosides from the extract on five major CYP isoforms in vitro were analyzed using a luminescent CYP recombinant human enzyme assay. B. monnieri extract exhibited non-competitive inhibition of CYP2C19 (IC50/Ki = 23.67/9.5 µg/mL), CYP2C9 (36.49/12.5 µg/mL), CYP1A2 (52.20/25.1 µg/mL); competitive inhibition of CYP3A4 (83.95/14.5 µg/mL) and weak inhibition of CYP2D6 (IC50 = 2061.50 µg/mL). However, the bacosides showed negligible inhibition of the same isoforms. B. monnieri, which is orally administered, has a higher concentration in the gut than the liver; therefore, this herb could exhibit stronger inhibition of intestinal CYPs than hepatic CYPs. At an estimated gut concentration of 600 µg/mL (based on a daily dosage of 300 mg/day), B. monnieri reduced the catalytic activities of CYP3A4, CYP2C9 and CYP2C19 to less than 10% compared to the total activity (without inhibitor = 100%). These findings suggest that B. monnieri extract could contribute to herb-drug interactions when orally co-administered with drugs metabolized by CYP1A2, CYP3A4, CYP2C9 and CYP2C19.

  12. Inhibition of Human Cytochrome P450 Enzymes by Bacopa monnieri Standardized Extract and Constituents

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    Seetha Ramasamy

    2014-02-01

    Full Text Available Bacopa monnieri and the constituents of this plant, especially bacosides, possess various neuropharmacological properties. Like drugs, some herbal extracts and the constituents of their extracts alter cytochrome P450 (CYP enzymes, causing potential herb-drug interactions. The effects of Bacopa monnieri standardized extract and the bacosides from the extract on five major CYP isoforms in vitro were analyzed using a luminescent CYP recombinant human enzyme assay. B. monnieri extract exhibited non-competitive inhibition of CYP2C19 (IC50/Ki = 23.67/9.5 µg/mL, CYP2C9 (36.49/12.5 µg/mL, CYP1A2 (52.20/25.1 µg/mL; competitive inhibition of CYP3A4 (83.95/14.5 µg/mL and weak inhibition of CYP2D6 (IC50 = 2061.50 µg/mL. However, the bacosides showed negligible inhibition of the same isoforms. B. monnieri, which is orally administered, has a higher concentration in the gut than the liver; therefore, this herb could exhibit stronger inhibition of intestinal CYPs than hepatic CYPs. At an estimated gut concentration of 600 µg/mL (based on a daily dosage of 300 mg/day, B. monnieri reduced the catalytic activities of CYP3A4, CYP2C9 and CYP2C19 to less than 10% compared to the total activity (without inhibitor = 100%. These findings suggest that B. monnieri extract could contribute to herb-drug interactions when orally co-administered with drugs metabolized by CYP1A2, CYP3A4, CYP2C9 and CYP2C19.

  13. Utility of intersystem extrapolation factors in early reaction phenotyping and the quantitative extrapolation of human liver microsomal intrinsic clearance using recombinant cytochromes P450.

    Science.gov (United States)

    Chen, Yuan; Liu, Liling; Nguyen, Khanh; Fretland, Adrian J

    2011-03-01

    Reaction phenotyping using recombinant human cytochromes P450 (P450) has great utility in early discovery. However, to fully realize the advantages of using recombinant expressed P450s, the extrapolation of data from recombinant systems to human liver microsomes (HLM) is required. In this study, intersystem extrapolation factors (ISEFs) were established for CYP1A2, CYP2C8, CYP2C9, CYP2C19, CYP2D6, and CYP3A4 using 11 probe substrates, based on substrate depletion and/or metabolite formation kinetics. The ISEF values for CYP2C9, CYP2D6, and CYP3A4 determined using multiple substrates were similar across substrates. When enzyme kinetics of metabolite formation for CYP1A2, 2C9, 2D6, and 3A4 were used, the ISEFs determined were generally within 2-fold of that determined on the basis of substrate depletion. Validation of ISEFs was conducted using 10 marketed drugs by comparing the extrapolated data with published data. The major isoforms responsible for the metabolism were identified, and the contribution of the predominant P450s was similar to that of previously reported data. In addition, phenotyping data from internal compounds, extrapolated using the rhP450-ISEF method, were comparable to those obtained using an HLM-based inhibition assay approach. Moreover, the intrinsic clearance (CL(int)) calculated from extrapolated rhP450 data correlated well with measured HLM CL(int). The ISEF method established in our laboratory provides a convenient tool in early reaction phenotyping for situations in which the HLM-based inhibition approach is limited by low turnover and/or unavailable metabolite formation. Furthermore, this method allows for quantitative extrapolation of HLM intrinsic clearance from rhP450 phenotyping data simultaneously to obtaining the participating metabolizing enzymes.

  14. In Vitro Inhibitory Effects of Scutellarin on Six Human/Rat Cytochrome P450 Enzymes and P-glycoprotein

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    Yong-Long Han

    2014-05-01

    Full Text Available Inhibition of cytochrome P450 (CYP and P-glycoprotein (P-gp are regarded as the most frequent and clinically important pharmacokinetic causes among the various possible factors for drug-drug interactions. Scutellarin is a flavonoid which is widely used for the treatment of cardiovascular diseases. In this study, the in vitro inhibitory effects of scutellarin on six major human CYPs (CYP1A2, CYP2C8, CYP2C9, CYP2C19, CYP2D6, and CYP3A4 and six rat CYPs (CYP1A2, CYP2C7, CYP2C11, CYP2C79, CYP2D4, and CYP3A2 activities were examined by using liquid chromatography-tandem mass spectrometry. Meanwhile, the inhibitory effects of scutellarin on P-gp activity were examined on a human metastatic malignant melanoma cell line WM-266-4 by calcein-AM fluorometry screening assay. Results demonstrated that scutellarin showed negligible inhibitory effects on the six major CYP isoenzymes in human/rat liver microsomes with almost all of the IC50 values exceeding 100 μM, whereas it showed values of 63.8 μM for CYP2C19 in human liver microsomes, and 63.1 and 85.6 μM for CYP2C7 and CYP2C79 in rat liver microsomes, respectively. Scutellarin also showed weak inhibitory effect on P-gp. In conclusion, this study demonstrates that scutellarin is unlikely to cause any clinically significant herb-drug interactions in humans when co-administered with substrates of the six CYPs (CYP1A2, CYP2C8, CYP2C9, CYP2C19, CYP2D6, and CYP3A4 and P-gp.

  15. Cytochrome P450 aromatase expression in human seminoma

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    Montanaro Daniela

    2005-12-01

    Full Text Available Abstract Background The enzyme cytochrome P450 aromatase, catalysing the conversion of androgens into estrogens, has been detected in normal human testicular cells suggesting a physiological role of local estrogen biosynthesis on spermatogenesis control. Estrogens, regulating cell growth and apoptosis, can also be involved in tumorigenesis process, but the possible link between estrogens and testicular neoplastic process is, up to now, scarcely known. This study examined aromatase expression in human seminoma, which is the most common germ cell tumour of the testis. Methods The tumour-bearing testes were obtained from 20 patients with classic seminoma undergoing to therapeutic orchidectomy. Paraffin embedded tissues were processed for immunohistochemistry using a mouse monoclonal antibody generated against human placental cytochrome P450 arom, as primary antibody, and a biotinylated goat-anti-mouse IgG, as secondary antibody. Furthermore, Western blot analysis of seminoma extracts was carried out. Results Intense P450 arom immunoreactivity was observed in the seminoma cells and Western blot analysis confirmed the immunodetection. A strong immunostaining was also detected in cells of intratubular germ cell neoplasia (IGCN, adjacent to seminoma. Conclusion The present study demonstrated, for the first time in human, aromatase expression in neoplastic cells of seminoma suggesting a relation between local estrogen biosynthesis and germ cell tumorigenesis. The P450 arom immunolocalization in the cells of IGCN, representing the common precursor of most germ cell tumors, seems to support these findings.

  16. Effect of Honokiol on Cytochrome P450 and UDP-Glucuronosyltransferase Enzyme Activities in Human Liver Microsomes

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    Yong Yeon Cho

    2013-09-01

    Full Text Available Honokiol is a bioactive component isolated from the medicinal herbs Magnolia officinalis and Magnolia grandiflora that has antioxidative, anti-inflammatory, antithrombotic, and antitumor activities. The inhibitory potentials of honokiol on eight major human cytochrome P450 (CYP enzymes 1A2, 2A6, 2B6, 2C8, 2C9, 2C19, 2D6, and 3A4, and four UDP-glucuronosyltransferases (UGTs 1A1, 1A4, 1A9, and 2B7 in human liver microsomes were investigated using liquid chromatography-tandem mass spectrometry. Honokiol strongly inhibited CYP1A2-mediated phenacetin O-deethylation, CYP2C8-mediated amodiaquine N-deethylation, CYP2C9-mediated diclofenac 4-hydroxylation, CYP2C19-mediated [S]-mephenytoin 4-hydroxylation, and UGT1A9-mediated propofol glucuronidation with Ki values of 1.2, 4.9, 0.54, 0.57, and 0.3 μM, respectively. Honokiol also moderately inhibited CYP2B6-mediated bupropion hydroxylation and CYP2D6-mediated bufuralol 1'-hydroxylation with Ki values of 17.5 and 12.0 μM, respectively. These in vitro results indicate that honokiol has the potential to cause pharmacokinetic drug interactions with other co-administered drugs metabolized by CYP1A2, CYP2C8, CYP2C9, CYP2C19, and UGT1A9.

  17. The effect of organic solvents on enzyme kinetic parameters of human CYP3A4 and CYP1A2 in vitro.

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    Rokitta, Dennis; Pfeiffer, Kay; Streich, Christina; Gerwin, Henrik; Fuhr, Uwe

    2013-10-01

    Abstract Enzyme kinetic parameters provide essential quantitative information about characterization of individual steps in drug metabolism. Such enzymes are located in a (partially) aqueous environment. For in vitro measurements potential lipophilic substrates regularly require organic solvents to achieve concentrations sufficient for access of the drug to the binding site of the enzyme. However, solvents may interact with the enzymes. In this study, we investigated the effects of methanol, ethanol, acetonitrile and dimethyl sulfoxide (1% to 4%) on the assessment of km, Vmax and Clint for the metabolism of midazolam via CYP3A4 to 1-hydroxymidazolam and the metabolism of caffeine to paraxanthine via CYP1A2 using expressed enzymes in vitro. The presence of acetonitrile proved the highest apparent Vmax value for paraxanthine formation but the lowest values for 1-hydroxymidazolam formation. The km value for midazolam showed no systematic effects of organic solvents, while for caffeine km was up to 8-fold lower for solvent free samples compared to solvent containing samples. The present example suggests that effects of solvents may considerably influence enzyme kinetic parameters beyond a mere change in apparent activity. These effects illustrate a difference for individual enzyme--substrate pairs, solvents, and solvent concentrations. What remains is the determination to which extent these effects compromise in vitro-in vivo extrapolations, and which solvents are most appropriate.

  18. In vitro inhibition and induction of human liver cytochrome P450 enzymes by gentiopicroside: potent effect on CYP2A6.

    Science.gov (United States)

    Deng, Yating; Wang, Lu; Yang, Yong; Sun, Wenji; Xie, Renming; Liu, Xueying; Wang, Qingwei

    2013-01-01

    Gentiopicroside (GE), a naturally occurring iridoid glycoside, has been developed into a Novel Traditional Chinese Drug named gentiopicroside injection, and it was approved for the treatment of acute jaundice and chronic active hepatitis by SFDA. However, the inhibitory and inducible effects of GE on the activity of cytochrome P450 (CYP450) are unclear. The purpose of this study was to evaluate the ability of GE to inhibit and induce human cytochrome P450 enzymes in vitro. In human liver microsomes, GE inhibited CYP2A6 and CYP2E1 in a concentration-dependent manner, with IC₅₀ values of 21.8 µg/ml and 594 µg/ml, respectively, and the IC₅₀ of CYP2A6 was close to the C(max) value observed clinically. GE was a non-competitive inhibitor of CYP2A6 at lower concentrations and a competitive inhibitor at higher concentrations. GE did not produce inhibition of CYP2C9, CYP2D6, CYP1A2 or CYP3A4 activities. However, a significant increase of CYP1A2 and CYP3A4 activity was observed at high concentrations. In cultured human hepatocytes no significant induction of CYP1A2, CYP3A4 or CYP2B6 was observed. Given these results, the in vivo potential inhibition of GE on CYP2A6 deserves further investigation, and it seems that the hepatoprotective effect of GE is irrelevant to its effect on P450s.

  19. Identification of cytochrome P450 isoforms involved in the metabolism of paroxetine and estimation of their importance for human paroxetine metabolism using a population-based simulator

    DEFF Research Database (Denmark)

    Jornil, Jakob; Jensen, Klaus Gjervig; Larsen, Frank

    2010-01-01

    the importance of the identified paroxetine-metabolizing P450 isoforms for human metabolism, taking mechanism-based inhibition into account. The amount of active hepatic CYP2D6 and CYP3A4 (not inactivated by mechanism-based inhibition) was also estimated by Simcyp. For extensive and poor metabolizers of CYP2D6......We identify here for the first time the low-affinity cytochrome P450 (P450) isoforms that metabolize paroxetine, using cDNA-expressed human P450s measuring substrate depletion and paroxetine-catechol (product) formation by liquid chromatography-tandem mass spectrometry. CYP1A2, CYP2C19, CYP2D6, CYP......3A4, and CYP3A5 were identified as paroxetine-catechol-forming P450 isoforms, and CYP2C19 and CYP2D6 were identified as metabolizing P450 isoforms by substrate depletion. Michaelis-Menten constants K(m) and V(max) were determined by product formation and substrate depletion. Using selective...

  20. Genotoxicity of tamoxifen, tamoxifen epoxide and toremifene in human lymphoblastoid cells containing human cytochrome P450s.

    Science.gov (United States)

    Styles, J A; Davies, A; Lim, C K; De Matteis, F; Stanley, L A; White, I N; Yuan, Z X; Smith, L L

    1994-01-01

    The clastogenicity of tamoxifen and toremifene was tested in six human lymphoblastoid cell lines each expressing increased monooxygenase activity associated with a specific transfected human cytochrome P450 cDNA (CYP1A1, CYP1A2, CYP2D6, CYP2E1 or CYP3A4). The chemicals were also tested in a cell line (MCL-5) expressing elevated native CYP1A1 and containing transfected CYP1A2, CYP2A6, CYP2E1 and CYP3A4 and epoxide hydrolase, and in a cell line containing only the viral vector (Ho1). Dose-related increases in micronuclei were observed when cells expressing 2E1, 3A4, 2D6 or MCL-5 cells were exposed to tamoxifen. The positive responses in the cell lines were in the order MCL-5 > 2E1 > 3A4 > 2D6. Toremifene also gave positive results with 2E1, 3A4 and MCL-5 cells, although the responses were less marked and the positive effects required higher doses than with tamoxifen. A synthesized epoxide of tamoxifen was also tested in these cell lines and produced similar increases in the incidences of micronucleated cells. The increases in the responses observed with the epoxide were greater than with tamoxifen or toremifene. The P450 isoenzyme activities in these cells were in a range similar to those of human tumour-derived cell lines. Microsomes (1A1, 2A2, 2A6, 2B6, 2E1, 3A4 and 2D6) from these cells all metabolized tamoxifen. The major metabolite detected by HPLC was N-desmethyltamoxifen, and 4-hydroxytamoxifen was also detected in cells with cytochrome P450 2E1 and 2D6. These results are consistent with the following conclusions. (1) Tamoxifen requires metabolic activation to DNA-reactive species by specific CYP monooxygenases in order to exert its genotoxic effects. (2) The positive clastogenic effects elicited in lymphoblastoid cells by tamoxifen epoxide suggest that the genotoxic (and possibly the carcinogenic) effects of tamoxifen may be due to one or more epoxide metabolites that are generated intracellularly, probably in close proximity to the nucleus. (3) Tamoxifen is

  1. Marmoset cytochrome P450 2J2 mainly expressed in small intestines and livers effectively metabolizes human P450 2J2 probe substrates, astemizole and terfenadine.

    Science.gov (United States)

    Uehara, Shotaro; Uno, Yasuhiro; Inoue, Takashi; Okamoto, Eriko; Sasaki, Erika; Yamazaki, Hiroshi

    2016-11-01

    1. Common marmoset (Callithrix jacchus), a New World Monkey, has potential to be a useful animal model in preclinical studies. However, drug metabolizing properties have not been fully understood due to insufficient information on cytochrome P450 (P450), major drug metabolizing enzymes. 2. Marmoset P450 2J2 cDNA was isolated from marmoset livers. The deduced amino acid sequence showed a high-sequence identity (91%) with cynomolgus monkey and human P450 2J2 enzymes. A phylogenetic tree revealed that marmoset P450 2J2 was evolutionarily closer to cynomolgus monkey and human P450 2J2 enzymes, than P450 2J forms in pigs, rabbits, rats or mice. 3. Marmoset P450 2J2 mRNA was abundantly expressed in the small intestine and liver, and to a lesser extent in the brain, lung and kidney. Immunoblot analysis also showed expression of marmoset P450 2J2 protein in the small intestine and liver. 4. Enzyme assays using marmoset P450 2J2 protein heterologously expressed in Escherichia coli indicated that marmoset P450 2J2 effectively catalyzed astemizole O-demethylation and terfenadine t-butyl hydroxylation, similar to human and cynomolgus monkey P450 2J2 enzymes. 5. These results suggest the functional characteristics of P450 2J2 enzymes are similar among marmosets, cynomolgus monkeys and humans.

  2. CONSTITUTIVE ANDROSTANE RECEPTOR DEPENDENT AND INDEPENDENT MODULATION OF CYP3A2, CYP1A2 BY PHENOBARBITAL AND FIBRATE IN RATS’ LIVER

    Directory of Open Access Journals (Sweden)

    Zein Shaban Ibrahim

    2013-01-01

    Full Text Available Cytochrome P450 enzymes, CYP3A and CYP1A are major drug metabolizing enzymes in the liver. CYP3A enzymes have a major role in the metabolism of 30-40% of all used drugs. CYP1A2 is a key enzyme having an important role in the metabolic clearance of 5% of currently marketed drugs. CYP1A2 participates in the metabolic activation of chemical mutagens in cooked food, therefore its activity is suspected to be one of the possible risk factors determining the carcinogenicity of heterocyclic amines in human beings. In a previous report, we have reported the induction of CYP3A2 and the inhibition of CYP1A2 by Fibrate (CFA and proved CYP1A2 inhibition to be PPARα-dependent. CYP3A2 and CYP1A2 have been reported to be induced in the liver by Phenobarbital (PB while Fibrates was reported to induce CYP3A2. However the exact mechanism of the induction of CYP3A2 by CFA and PB and induction of CYP1A2 by PB has not been clarified yet whether it is through Constitutive Androstane Receptor (CAR or other receptor as PPARα or Pregnane X Receptor (PXR. We treated Wistar female rats (with normal expression of CAR protein and Wistar femal Kyoto rats (with low expression of CAR protein with PB and Clofibric Acid (CFA. PB caused a high CYP3A2 induction in Wistar female rats and a low induction in (WKY indicating that PB induced CYP3A2 in a CAR-dependent manner. Interestingly, PB treatment induced CYP1A2 in Wistar female rats and failed to induce it in (WKY indicating that the induction of CYP1A2 by PB to be CAR-dependent. Moreover CFA induced CYP3A2 protein similarly in both rat strains indicating that CYP3A2 induction by Fibrates is CAR-independent and most probably to be PXR or PPARα-dependent. For the best of our knowledge this is the first report that shows a clear evidence of the CAR-dependent induction of CYP1A2 and CYP3A2 by PB and the CAR-independent induction of CYP3A2 by fibrates.

  3. In vitro metabolism of a novel PPAR gamma agonist, KR-62980, and its stereoisomer, KR-63198, in human liver microsomes and by recombinant cytochrome P450s.

    Science.gov (United States)

    Kim, K-B; Seo, K-A; Yoon, Y-J; Bae, M-A; Cheon, H G; Shin, J-G; Liu, K-H

    2008-09-01

    1. KR-62980 and its stereoisomer KR-63198 are novel and selective peroxisome proliferator-activated receptor gamma (PPAR gamma) modulators with activity profiles different from that of rosiglitazone. This study was performed to identify the major metabolic pathways for KR-62980 and KR-63198 in human liver microsomes. 2. Human liver microsomal incubation of KR-62980 and KR-63198 in the presence of a beta-nicotinamide adenine dinucleotide phosphate (NADPH)-generating system resulted in hydroxy metabolite formation. In addition, the specific cytochrome P450s (CYPs) responsible for KR-62980 and KR-63198 hydroxylation were identified by using a combination of chemical inhibition in human liver microsomes and metabolism by recombinant P450s. It is shown that CYP1A2, CYP2D6, CYP3A4, and CYP3A5 are the predominant enzymes in the hydroxylation of KR-62980 and KR-63198. 3. The intrinsic clearance through hydroxylation was consistently and significantly higher for KR-62980 than for KR-63198, indicating metabolic stereoselectivity (CL(int) of 0.012 +/- 0.001 versus 0.004 +/- 0.001 microl min(-1) pmol(-1) P450, respectively). 4. In a drug-drug interaction study, KR-62980 and KR-63198 had no effect on the activities of the P450s tested (IC(50) > 50 microM), suggesting that in clinical interactions between KR-62980 and KR-63198 the P450s tested would not be expected.

  4. Coupled motions direct electrons along human microsomal P450 Chains.

    Directory of Open Access Journals (Sweden)

    Christopher R Pudney

    2011-12-01

    Full Text Available Protein domain motion is often implicated in biological electron transfer, but the general significance of motion is not clear. Motion has been implicated in the transfer of electrons from human cytochrome P450 reductase (CPR to all microsomal cytochrome P450s (CYPs. Our hypothesis is that tight coupling of motion with enzyme chemistry can signal "ready and waiting" states for electron transfer from CPR to downstream CYPs and support vectorial electron transfer across complex redox chains. We developed a novel approach to study the time-dependence of dynamical change during catalysis that reports on the changing conformational states of CPR. FRET was linked to stopped-flow studies of electron transfer in CPR that contains donor-acceptor fluorophores on the enzyme surface. Open and closed states of CPR were correlated with key steps in the catalytic cycle which demonstrated how redox chemistry and NADPH binding drive successive opening and closing of the enzyme. Specifically, we provide evidence that reduction of the flavin moieties in CPR induces CPR opening, whereas ligand binding induces CPR closing. A dynamic reaction cycle was created in which CPR optimizes internal electron transfer between flavin cofactors by adopting closed states and signals "ready and waiting" conformations to partner CYP enzymes by adopting more open states. This complex, temporal control of enzyme motion is used to catalyze directional electron transfer from NADPH→FAD→FMN→heme, thereby facilitating all microsomal P450-catalysed reactions. Motions critical to the broader biological functions of CPR are tightly coupled to enzyme chemistry in the human NADPH-CPR-CYP redox chain. That redox chemistry alone is sufficient to drive functionally necessary, large-scale conformational change is remarkable. Rather than relying on stochastic conformational sampling, our study highlights a need for tight coupling of motion to enzyme chemistry to give vectorial electron

  5. Metabolism of the major Echinacea alkylamide N-isobutyldodeca-2E,4E,8Z,10Z-tetraenamide by human recombinant cytochrome P450 enzymes and human liver microsomes.

    Science.gov (United States)

    Toselli, F; Matthias, A; Bone, K M; Gillam, E M J; Lehmann, R P

    2010-08-01

    Echinacea preparations are used for the treatment and prevention of upper respiratory tract infections. The phytochemicals believed responsible for the immunomodulatory properties are the alkylamides found in ethanolic extracts, with one of the most abundant being the N-isobutyldodeca-2E,4E,8Z,10Z-tetraenamide (1). In this study, we evaluated the human cytochrome P450 enzymes involved in the metabolism of this alkylamide using recombinant P450s, human liver microsomes and pure synthetic compound. Epoxidation, N-dealkylation and hydroxylation products were detected, with different relative amounts produced by recombinant P450s and microsomes. The major forms showing activity toward the metabolism of 1 were CYP1A1, CYP1A2 (both producing the same epoxide and N-dealkylation product), CYP2A13 (producing two epoxides), and CYP2D6 (producing two epoxides and an hydroxylated metabolite). Several other forms showed less activity. In incubations with human liver microsomes and selective inhibitors, CYP2E1 was found to be principally responsible for producing the dominant, hydroxylation product, whereas CYP2C9 was the principal source of the epoxides and CYP1A2 was responsible for the dealkylation product. In summary, in this study the relative impacts of the main human xenobiotic-metabolizing cytochrome P450s on the metabolism of a major Echinacea alkylamide have been established and the metabolites formed have been identified.

  6. Marmoset cytochrome P450 2D8 in livers and small intestines metabolizes typical human P450 2D6 substrates, metoprolol, bufuralol and dextromethorphan.

    Science.gov (United States)

    Uehara, Shotaro; Uno, Yasuhiro; Hagihira, Yuya; Murayama, Norie; Shimizu, Makiko; Inoue, Takashi; Sasaki, Erika; Yamazaki, Hiroshi

    2015-01-01

    1. Although the New World non-human primate, the common marmoset (Callithrix jacchus), is a potentially useful animal model, comprehensive understanding of drug metabolizing enzymes is insufficient. 2. A cDNA encoding a novel cytochrome P450 (P450) 2D8 was identified in marmosets. The amino acid sequence deduced from P450 2D8 cDNA showed a high sequence identity (83-86%) with other primate P450 2Ds. Phylogenetic analysis showed that marmoset P450 2D8 was closely clustered with human P450 2D6, unlike P450 2Ds of miniature pig, dog, rabbit, guinea pig, mouse or rat. 3. Marmoset P450 2D8 mRNA was predominantly expressed in the liver and small intestine among the tissues types analyzed, whereas marmoset P450 2D6 mRNA was expressed predominantly in the liver where P450 2D protein was detected by immunoblotting. 4. By metabolic assays using marmoset P450 2D8 protein heterologously expressed in Escherichia coli, although P450 2D8 exhibits lower catalytic efficiency compared to marmoset and human P450 2D6 enzymes, P450 2D8 mediated O-demethylations of metoprolol and dextromethorphan and bufuralol 1'-hydroxylation. 5. These results suggest that marmoset P450 2D8 (also expressed in the extrahepatic tissues) has potential roles in drug metabolism in a similar manner to those of human and marmoset P450 2D6.

  7. AM-2201 Inhibits Multiple Cytochrome P450 and Uridine 5′-Diphospho-Glucuronosyltransferase Enzyme Activities in Human Liver Microsomes

    Directory of Open Access Journals (Sweden)

    Ju-Hyun Kim

    2017-03-01

    Full Text Available AM-2201 is a synthetic cannabinoid that acts as a potent agonist at cannabinoid receptors and its abuse has increased. However, there are no reports of the inhibitory effect of AM-2201 on human cytochrome P450 (CYP or uridine 5′-diphospho-glucuronosyltransferase (UGT enzymes. We evaluated the inhibitory effect of AM-2201 on the activities of eight major human CYPs (1A2, 2A6, 2B6, 2C8, 2C9, 2C19, 2D6, and 3A4 and six major human UGTs (1A1, 1A3, 1A4, 1A6, 1A9, and 2B7 enzymes in pooled human liver microsomes using liquid chromatography–tandem mass spectrometry to investigate drug interaction potentials of AM-2201. AM-2201 potently inhibited CYP2C9-catalyzed diclofenac 4′-hydroxylation, CYP3A4-catalyzed midazolam 1′-hydroxylation, UGT1A3-catalyzed chenodeoxycholic acid 24-acyl-glucuronidation, and UGT2B7-catalyzed naloxone 3-glucuronidation with IC50 values of 3.9, 4.0, 4.3, and 10.0 μM, respectively, and showed mechanism-based inhibition of CYP2C8-catalyzed amodiaquine N-deethylation with a Ki value of 2.1 μM. It negligibly inhibited CYP1A2, CYP2A6, CYP2B6, CYP2C19, CYP2D6, UGT1A1, UGT1A4, UGT1A6, and UGT1A9 activities at 50 μM in human liver microsomes. These in vitro results indicate that AM-2201 needs to be examined for potential pharmacokinetic drug interactions in vivo due to its potent inhibition of CYP2C8, CYP2C9, CYP3A4, UGT1A3, and UGT2B7 enzyme activities.

  8. AM-2201 Inhibits Multiple Cytochrome P450 and Uridine 5'-Diphospho-Glucuronosyltransferase Enzyme Activities in Human Liver Microsomes.

    Science.gov (United States)

    Kim, Ju-Hyun; Kwon, Soon-Sang; Kong, Tae Yeon; Cheong, Jae Chul; Kim, Hee Seung; In, Moon Kyo; Lee, Hye Suk

    2017-03-10

    AM-2201 is a synthetic cannabinoid that acts as a potent agonist at cannabinoid receptors and its abuse has increased. However, there are no reports of the inhibitory effect of AM-2201 on human cytochrome P450 (CYP) or uridine 5'-diphospho-glucuronosyltransferase (UGT) enzymes. We evaluated the inhibitory effect of AM-2201 on the activities of eight major human CYPs (1A2, 2A6, 2B6, 2C8, 2C9, 2C19, 2D6, and 3A4) and six major human UGTs (1A1, 1A3, 1A4, 1A6, 1A9, and 2B7) enzymes in pooled human liver microsomes using liquid chromatography-tandem mass spectrometry to investigate drug interaction potentials of AM-2201. AM-2201 potently inhibited CYP2C9-catalyzed diclofenac 4'-hydroxylation, CYP3A4-catalyzed midazolam 1'-hydroxylation, UGT1A3-catalyzed chenodeoxycholic acid 24-acyl-glucuronidation, and UGT2B7-catalyzed naloxone 3-glucuronidation with IC50 values of 3.9, 4.0, 4.3, and 10.0 μM, respectively, and showed mechanism-based inhibition of CYP2C8-catalyzed amodiaquine N-deethylation with a Ki value of 2.1 μM. It negligibly inhibited CYP1A2, CYP2A6, CYP2B6, CYP2C19, CYP2D6, UGT1A1, UGT1A4, UGT1A6, and UGT1A9 activities at 50 μM in human liver microsomes. These in vitro results indicate that AM-2201 needs to be examined for potential pharmacokinetic drug interactions in vivo due to its potent inhibition of CYP2C8, CYP2C9, CYP3A4, UGT1A3, and UGT2B7 enzyme activities.

  9. Reversible inhibition of three important human liver cytochrome p450 enzymes by tiliroside.

    Science.gov (United States)

    Sun, Dong-Xue; Lu, Jin-Cai; Fang, Zhong-Ze; Zhang, Yan-Yan; Cao, Yun-Feng; Mao, Yu-Xi; Zhu, Liang-Liang; Yin, Jun; Yang, Ling

    2010-11-01

    Tiliroside, an active flavonoid extensively found in many medicinal plants including Helichrysum italicum, Geranium mexicanum and Helianthemum glomeratum, has been demonstrated to exert multiple biological effects including antiinflammatory, antimicrobial, antioxidant and antitumor activities. Cytochrome P450 (CYP) enzymes play an important role in the Phase I oxidation metabolism of a wide range of xenobiotics and inhibition of CYP isoforms might influence the elimination of drugs and induce serious adverse drug response. The inhibition of seven CYP isoforms (CYP3A4, CYP1A2, CYP2A6, CYP2D6, CYP2C9, CYP2C8 and CYP2E1) by tiliroside was investigated using in vitro human liver microsomal incubation assays. The results showed that tiliroside strongly inhibited the activity of CYP3A4 (IC(50) = 9.0 ± 1.7 μm), CYP2C8 (IC(50) = 12.1 ± 0.9 μm) and CYP2C9 (IC(50) = 10.2 ± 0.9 μm) with other CYP isoforms negligibly influenced. Further kinetic analysis showed that inhibition of these three CYP isoforms by tiliroside is best fit to a competitive way. The K(i) value was calculated to be 5.5 μm, 3.3 μm, 9.4 μm for CYP3A4, CYP2C9 and CYP2C8, respectively. The relatively low K(i) values suggested that tiliroside might induce drug-drug interactions with many clinically used drugs which are mainly metabolized by these three CYP isoforms. Therefore, attention should be given to the probable drug-drug interaction between tiliroside-containing herbs and substrates of CYP3A4, CYP2C9 and CYP2C8.

  10. [Inhibitory effect of imperatorin and isoimperatorin on activity of cytochrome P450 enzyme in human and rat liver microsomes].

    Science.gov (United States)

    Cao, Yan; Zhong, Yu-Huan; Yuan, Mei; Li, Hua; Zhao, Chun-Jie

    2013-04-01

    Imperatorin (IM) and isoimperatorin (ISOIM) are major active components of common herbal medicines from Umbelliferae plants, and widely used in clinic. This article studies the inhibitory effect of IM and ISOIM on the activity of cytochrome P450 (CYP) enzyme, and assesses their potential drug-drug interaction. IM and ISOIM were incubated separately with human or rat liver microsomes for 30 min, with phenacetin, bupropion, tolbutamide, S-mephenytoin, dextromethorphan and midazolam as probe substrates. Metabolites of the CYP probe substrates were determined by LC-MS/MS, and IC50 values were calculated to assess the inhibitory effect of the two drugs on human CYP1A2, 2B6, 2C9, 2C19, 2D6 and 3A4 enzymes, as well as on rat CYP1A2, 2B6, 2D2 and 3A1/2, and grade their inhibitory intensity. In human liver microsomes, IM and ISOIM showed different inhibitory effects on all of the six CYP isoenzymes. They were strong inhibitors for 1A2 and 2B6. The IC50 values were 0.05 and 0.20 micromol x L(-1) for 1A2, and 0.18 and 1.07 micromol x L(-1) for 2B6, respectively. They also showed moderate inhibitory effect on 2C19, and weak effect on 2C9, 2D6 and 3A4. In rat liver microsomes, IM and ISOIM were identified as moderate inhibitors for 1A2, with IC50 values of 1.95 and 2.98 micromol x L(-1). They were moderate and weak inhibitors for 2B6, with IC50 values of 6.22 and 21.71 micromol x L(-1), respectively. They also had weaker inhibitory effect on 2D2 and 3A1/2. The results indicated that IM and ISOIM had extensive inhibitory effects on human CYP enzymes. They are strong inhibitors of CYP1 A2 and 2B6 enzymes. However, it is worth noting the interaction arising from the inhibitory effect of CYP enzymes in clinic.

  11. In vitro investigation of cytochrome P450-mediated metabolism of dietary flavonoids

    DEFF Research Database (Denmark)

    Breinholt, Vibeke; Offord, E.A.; Brouwer, C.

    2002-01-01

    Human and mouse liver microsomes And membranes isolated from Escherichia coli, which expressed cytochrome P450 (CYP) 1A2, 3A4 2C9 or 2D6, were used to investigate CYP-mediated metabolism of five selected dietary flavonoids. In human and mouse liver microsomes kaempferol, apigenin and naringenin w...

  12. Application of a higher throughput approach to derive apparent Michaelis-Menten constants of isoform-selective p450-mediated biotransformation reactions in human hepatocytes.

    Science.gov (United States)

    Li, Albert P; Schlicht, Kari E

    2014-01-01

    A higher throughput platform was developed for the determination of K(M) values for isoformselective P450 substrates in human hepatocytes via incubation of the hepatocytes with substrates in 384- well plates and metabolite quantification by RapidFire™ mass spectrometry. Isoform-selective P450 substrates were incubated at 8 concentrations in triplicate with cryopreserved human hepatocytes from 16 donors. The metabolic pathways examined were the CYP1A2-catalyzed tacrine 1-hydroxylation, CYP2B6-catalyzed bupropion hydroxylation, CYP2C8-catalyzed amodiaquine N-deethylation, CYP2C9- catalyzed diclofenac 4'-hydroxylation, CYP2D6-catalyzed dextromethorphan O-demethylation, and CYP3A4-catalyzed midazolam 1'-hydroxylation. Typical saturation enzyme kinetics was observed for all the pathways evaluated. Individual differences in the apparent V(max) and K(M) values were observed among the human hepatocytes from each of the 16 individual donors, with no statistically significant gender- or age-associated differences. A "composite" K(M) value was calculated for each of the pathways via normalizing the individual activities to their respective V(max) values to develop "relative activities" followed by Michaelis-Menten analysis of the mean relative activities of the 16 donors at each of the 8 substrate concentrations. The resulting "composite" K(M) values for the P450 substrates may be used to guide in vitro P450 inhibition and induction studies and kinetic modeling of in vivo drug-drug interaction.

  13. Hepatic Cytochrome P450 Activity, Abundance, and Expression Throughout Human Development.

    Science.gov (United States)

    Sadler, Natalie C; Nandhikonda, Premchendar; Webb-Robertson, Bobbie-Jo; Ansong, Charles; Anderson, Lindsey N; Smith, Jordan N; Corley, Richard A; Wright, Aaron T

    2016-07-01

    Cytochrome P450s are oxidative metabolic enzymes that play critical roles in the biotransformation of endogenous compounds and xenobiotics. The expression and activity of P450 enzymes varies considerably throughout human development; the deficit in our understanding of these dynamics limits our ability to predict environmental and pharmaceutical exposure effects. In an effort to develop a more comprehensive understanding of the ontogeny of P450 enzymes, we employed a multi-omic characterization of P450 transcript expression, protein abundance, and functional activity. Modified mechanism-based inhibitors of P450s were used as chemical probes for isolating active P450 proteoforms in human hepatic microsomes with developmental stages ranging from early gestation to late adult. High-resolution liquid chromatography-mass spectrometry was used to identify and quantify probe-labeled P450s, allowing for a functional profile of P450 ontogeny. Total protein abundance profiles and P450 rRNA was also measured, and our results reveal life-stage-dependent variability in P450 expression, abundance, and activity throughout human development and frequent discordant relationships between expression and activity. We have significantly expanded the knowledge of P450 ontogeny, particularly at the level of individual P450 activity. We anticipate that these results will be useful for enabling predictive therapeutic dosing, and for avoiding potentially adverse and harmful reactions during maturation from both therapeutic drugs and environmental xenobiotics. Copyright © 2016 by The American Society for Pharmacology and Experimental Therapeutics.

  14. Metabolism of the A{sub 1} adenosine receptor PET ligand [{sup 18}F]CPFPX by CYP1A2: implications for bolus/infusion PET studies

    Energy Technology Data Exchange (ETDEWEB)

    Matusch, Andreas [Institute of Medicine, Research Center Juelich GmbH, D-52425 Juelich (Germany); Meyer, Philipp T. [Department of Neurology, University Hospital Aachen, D-52074 Aachen (Germany); Bier, Dirk [Institute for Neuroscience and Biophysics (INB4)-Nuclear Chemistry, Research Center Juelich GmbH, D-52425 Juelich (Germany); Holschbach, Marcus H. [Institute for Neuroscience and Biophysics (INB4)-Nuclear Chemistry, Research Center Juelich GmbH, D-52425 Juelich (Germany); Woitalla, Dirk [Neurological Department, Ruhr-University Bochum, D-44791 Bochum (Germany); Elmenhorst, David [Institute of Medicine, Research Center Juelich GmbH, D-52425 Juelich (Germany); Winz, Oliver H. [Institute of Medicine, Research Center Juelich GmbH, D-52425 Juelich (Germany); Zilles, Karl [Institute of Medicine, Research Center Juelich GmbH, D-52425 Juelich (Germany); Bauer, Andreas [Institute of Medicine, Research Center Juelich GmbH, D-52425 Juelich (Germany)]. E-mail: an.bauer@fz-juelich.de

    2006-10-15

    The A{sub 1} adenosine receptor positron emission tomography (PET) ligand 8-cyclopentyl-3-(3-[{sup 18}F]fluoropropyl)-1-propylxanthine ([{sup 18}F]CPFPX, ) undergoes a fast hepatic metabolism. An optimal design of PET quantitation approaches (e.g., bolus/infusion studies) necessitates the knowledge of factors that influence this metabolism. Metabolites of were separated by radio thin-layer chromatography. Metabolism in vivo, in pooled human liver microsomes and in recombinant human cytochrome isoenzyme preparations was studied. Dynamic PET studies using were performed on three controls and two patients, one treated with the antidepressant and inhibitor of cytochrome CYP1A2 fluvoxamine, the other suffering from liver cirrhosis. CPFPX is metabolized by cytochrome CYP1A2 with high selectivity [K {sub M}=1.1 {mu}M (95% confidence interval, or CI, 0.6-2.0 {mu}M) and V {sub max}=243 pmol min{sup -1} mg{sup -1} (95% CI, 112-373 pmol min{sup -1} mg{sup -1}) corresponding to 2.4 pmol min{sup -1} pmol{sup -1} cytochrome P-450]. This metabolism can competitively be inhibited by fluvoxamine with K {sub I}=68 nM (95% CI, 34-138 nM). At least eight compounds found in human plasma and in the CYP1A2 in vitro preparations have an identical migration pattern and account together for >90% and >80% of the respective metabolite yield. Metabolism was considerably delayed in the two patients. In conclusion, is metabolized by cytochrome CYP1A2. Its metabolism is therefore subdued to disease-related or xenobiotic-induced changes of CYP1A2 activity. The identification of the metabolic pathway of 1 allows to optimize image quantification in A{sub 1} adenosine receptor PET studies.

  15. The influence of a CYP1A2 polymorphism on the ergogenic effects of caffeine

    OpenAIRE

    Womack Christopher J; Saunders Michael J; Bechtel Marta K; Bolton David J; Martin Michael; Luden Nicholas D; Dunham Wade; Hancock Melyssa

    2012-01-01

    Abstract Background Although caffeine supplementation improves performance, the ergogenic effect is variable. The cause(s) of this variability are unknown. A (C/A) single nucleotide polymorphism at intron 1 of the cytochrome P450 (CYP1A2) gene influences caffeine metabolism and clinical outcomes from caffeine ingestion. The purpose of this study was to determine if this polymorphism influences the ergogenic effect of caffeine supplementation. Methods Thirty-five trained male cyclists (age = 2...

  16. Interaction of rocuronium with human liver cytochromes P450.

    Science.gov (United States)

    Anzenbacherova, Eva; Spicakova, Alena; Jourova, Lenka; Ulrichova, Jitka; Adamus, Milan; Bachleda, Petr; Anzenbacher, Pavel

    2015-02-01

    Rocuronium is a neuromuscular blocking agent acting as a competitive antagonist of acetylcholine. Results of an inhibition of eight individual liver microsomal cytochromes P450 (CYP) are presented. As the patients are routinely premedicated with diazepam, possible interaction of diazepam with rocuronium has been also studied. Results indicated that rocuronium interacts with human liver microsomal CYPs by binding to the substrate site. Next, concentration dependent inhibition of liver microsomal CYP3A4 down to 42% (at rocuronium concentration 189 μM) was found. This effect has been confirmed with two CYP3A4 substrates, testosterone (formation of 6β-hydroxytestosterone) and diazepam (temazepam formation). CYP2C9 and CYP2C19 activities were inhibited down to 75-80% (at the same rocuronium concentration). Activities of other microsomal CYPs have not been inhibited by rocuronium. To prove the possibility of rocuronium interaction with other drugs (diazepam), the effect of rocuronium on formation of main diazepam metabolites, temazepam (by CYP3A4) and desmethyldiazepam, (also known as nordiazepam; formed by CYP2C19) in primary culture of human hepatocytes has been examined. Rocuronium has caused inhibition of both reactions by 20 and 15%, respectively. The results open a possibility that interactions of rocuronium with drugs metabolized by CYP3A4 (and possibly also CYP2C19) may be observed. Copyright © 2014 Japanese Pharmacological Society. Production and hosting by Elsevier B.V. All rights reserved.

  17. Characterization of human cytochrome P450 induction by pesticides.

    Science.gov (United States)

    Abass, Khaled; Lämsä, Virpi; Reponen, Petri; Küblbeck, Jenni; Honkakoski, Paavo; Mattila, Sampo; Pelkonen, Olavi; Hakkola, Jukka

    2012-03-29

    Pesticides are a large group of structurally diverse toxic chemicals. The toxicity may be modified by cytochrome P450 (CYP) enzyme activity. In the current study, we have investigated effects and mechanisms of 24 structurally varying pesticides on human CYP expression. Many pesticides were found to efficiently activate human pregnane X receptor (PXR) and/or constitutive androstane receptor (CAR). Out of the 24 compounds tested, 14 increased PXR- and 15 CAR-mediated luciferase activities at least 2-fold. While PXR was predominantly activated by pyrethroids, CAR was, in addition to pyrethroids, well activated by organophosphates and several carbamates. Induction of CYP mRNAs and catalytic activities was studied in the metabolically competent, human derived HepaRG cell line. CYP3A4 mRNA was induced most powerfully by pyrethroids; 50 μM cypermethrin increased CYP3A4 mRNA 35-fold. CYP2B6 was induced fairly equally by organophosphate, carbamate and pyrethroid compounds. Induction of CYP3A4 and CYP2B6 by these compound classes paralleled their effects on PXR and CAR. The urea herbicide diuron and the triazine herbicide atrazine induced CYP2B6 mRNA more than 10-fold, but did not activate CAR indicating that some pesticides may induce CYP2B6 via CAR-independent mechanisms. CYP catalyzed activities were induced much less than the corresponding mRNAs. At least in some cases, this is probably due to significant inhibition of CYP enzymes by the studied pesticides. Compared with human CAR activation and CYP2B6 expression, pesticides had much less effect on mouse CAR and CYP2B10 mRNA. Altogether, pesticides were found to be powerful human CYP inducers acting through both PXR and CAR. Copyright © 2012 Elsevier Ireland Ltd. All rights reserved.

  18. Potent inhibition of cytochrome P450 2B6 by sibutramine in human liver microsomes.

    Science.gov (United States)

    Bae, Soo Hyeon; Kwon, Min Jo; Choi, Eu Jin; Zheng, Yu Fen; Yoon, Kee Dong; Liu, Kwang-Hyeon; Bae, Soo Kyung

    2013-09-05

    The present study was performed to evaluate the potency and specificity of sibutramine as an inhibitor of the activities of nine human CYP isoforms in liver microsomes. Using a cocktail assay, the effects of sibutramine on specific marker reactions of the nine CYP isoforms were measured in human liver microsomes. Sibutramine showed potent inhibition of CYP2B6-mediated bupropion 6-hydroxylation with an IC50 value of 1.61μM and Ki value of 0.466μM in a competitive manner at microsomal protein concentrations of 0.25mg/ml; this was 3.49-fold more potent than the typical CYP2B6 inhibitor thio-TEPA (Ki=1.59μM). In addition, sibutramine slightly inhibited CYP2C19 activity (Ki=16.6μM, noncompetitive inhibition) and CYP2D6 activity (Ki=15.7μM, noncompetitive inhibition). These observations indicated 35.6- and 33.7-fold decreases in inhibition potency, respectively, compared with that of CYP2B6 by sibutramine. However, no inhibition of CYP1A2, CYP2A6, CYP2C8, CYP2C9, CYP2D6, or CYP2E1 activities was observed. In addition, the CYP2B6 inhibitory potential of sibutramine was enhanced at a lower microsomal protein concentration of 0.05mg/ml. After 30min preincubation of human liver microsomes with sibutramine in the presence of NADPH, no shift in IC50 was observed in terms of inhibition of the activities of the nine CYPs, suggesting that sibutramine is not a time-dependent inactivator. These observations suggest that sibutramine is a selective and potent inhibitor of CYP2B6 in vitro, whereas inhibition of other CYPs is substantially lower. These in vitro data support the use of sibutramine as a well-known inhibitor of CYP2B6 for routine screening of P450 reversible inhibition when human liver microsomes are used as the enzyme source.

  19. Why dried blood spots are an ideal tool for CYP1A2 phenotyping.

    Science.gov (United States)

    De Kesel, Pieter M M; Lambert, Willy E; Stove, Christophe P

    2014-08-01

    Dried blood spot (DBS) sampling has gained wide interest in bioanalysis during the last decade and has already been successfully applied in pharmacokinetic and phenotyping studies. However, all of the available phenotyping studies used small datasets and did not include a systematic evaluation of DBS-specific parameters. The latter is important since several of these factors still challenge the breakthrough of DBS in routine practice. In this study, caffeine and paraxanthine are determined in capillary DBS, venous DBS, whole blood and plasma for cytochrome P450 (CYP) 1A2 phenotyping. The aim of this study was to explore the usefulness of DBS as a tool for CYP1A2 phenotyping. A CYP1A2 phenotyping study was conducted in 73 healthy volunteers who received a 150 mg oral dose of caffeine. Six hours post-administration, caffeine and paraxanthine concentrations and paraxanthine:caffeine molar concentration ratios, i.e., the actual CYP1A2 phenotyping indices, were determined in capillary DBS (obtained by non-volumetric application, direct from the fingertip), venous DBS, whole blood, and plasma. Furthermore, the impact of DBS-specific parameters, including hematocrit, volume spotted, and punch location, was evaluated. Concentrations of caffeine and paraxanthine in capillary DBS were, respectively, on average 12.7 and 13.8% lower than those in venous DBS and 31.5 and 33.1% lower than those in plasma. While these differences were statistically significant (p phenotyping study to date, we have demonstrated that CYP1A2 phenotyping in capillary DBS is a valid and convenient alternative for the classical plasma-based approach. Additionally, we have provided an objective basis as to why DBS are an ideal tool for CYP1A2 phenotyping.

  20. Inhibitory Effect of Selaginellins from Selaginella tamariscina (Beauv. Spring against Cytochrome P450 and Uridine 5′-Diphosphoglucuronosyltransferase Isoforms on Human Liver Microsomes

    Directory of Open Access Journals (Sweden)

    Jae-Kyung Heo

    2017-09-01

    Full Text Available Selaginella tamariscina (Beauv. has been used for traditional herbal medicine for treatment of cancer, hepatitis, and diabetes in the Orient. Numerous bioactive compounds including alkaloids, flavonoids, lignans, and selaginellins have been identified in this medicinal plant. Among them, selaginellins having a quinone methide unit and an alkylphenol moiety have been known to possess anticancer, antidiabetic, and neuroprotective activity. Although there have been studies on the biological activities of selaginellins, their modulatory potential of cytochrome P450 (P450 and uridine 5′-diphosphoglucuronosyltransferase (UGT activities have not been previously evaluated. In this study, we investigated the drug interaction potential of two selaginellins on ten P450 isoforms (CYP1A2, 2A6, 2B6, 2C8, 2C9, 2C19, 2D6, 2E1, 2J2 and 3A and six UGT isoforms (UGT1A1, 1A3, 1A4, 1A6, 1A9 and 2B7 using human liver microsomes and liquid chromatography-tandem mass spectrometry. Selaginellin and selaginellin M had high inhibitory potential for CYP2C8-mediated amodiaquine O-demethylation with IC50 values of 0.5 and 0.9 μM, respectively. Selaginellin and selaginellin M also showed medium inhibitory potential against CYP2C9, CYP2J2, UGT1A1, and UGT1A3 (1 μM < IC50 < 5 μM. These two selaginellins had low inhibitory potential against CYP1A2, CYP2A6, CYP2E1, and UGT1A6 (IC50 > 25 μM. This information might be helpful to predict possible drug interaction potential of between selaginellins and co-administered drugs.

  1. Differences in the Epigenetic Regulation of Cytochrome P450 Genes between Human Embryonic Stem Cell-Derived Hepatocytes and Primary Hepatocytes.

    Science.gov (United States)

    Park, Han-Jin; Choi, Young-Jun; Kim, Ji Woo; Chun, Hang-Suk; Im, Ilkyun; Yoon, Seokjoo; Han, Yong-Mahn; Song, Chang-Woo; Kim, Hyemin

    2015-01-01

    Human pluripotent stem cell-derived hepatocytes have the potential to provide in vitro model systems for drug discovery and hepatotoxicity testing. However, these cells are currently unsuitable for drug toxicity and efficacy testing because of their limited expression of genes encoding drug-metabolizing enzymes, especially cytochrome P450 (CYP) enzymes. Transcript levels of major CYP genes were much lower in human embryonic stem cell-derived hepatocytes (hESC-Hep) than in human primary hepatocytes (hPH). To verify the mechanism underlying this reduced expression of CYP genes, including CYP1A1, CYP1A2, CYP1B1, CYP2D6, and CYP2E1, we investigated their epigenetic regulation in terms of DNA methylation and histone modifications in hESC-Hep and hPH. CpG islands of CYP genes were hypermethylated in hESC-Hep, whereas they had an open chromatin structure, as represented by hypomethylation of CpG sites and permissive histone modifications, in hPH. Inhibition of DNA methyltransferases (DNMTs) during hepatic maturation induced demethylation of the CpG sites of CYP1A1 and CYP1A2, leading to the up-regulation of their transcription. Combinatorial inhibition of DNMTs and histone deacetylases (HDACs) increased the transcript levels of CYP1A1, CYP1A2, CYP1B1, and CYP2D6. Our findings suggest that limited expression of CYP genes in hESC-Hep is modulated by epigenetic regulatory factors such as DNMTs and HDACs.

  2. Role of cytochrome P450 and UDP-glucuronosyltransferases in metabolic pathway of homoegonol in human liver microsomes.

    Science.gov (United States)

    Kwon, Soon Sang; Kim, Ju Hyun; Jeong, Hyeon-Uk; Ahn, Kyung-Seop; Oh, Sei-Ryang; Lee, Hye Suk

    2015-08-01

    Homoegonol is being evaluated for the development of a new antiasthmatic drug. Based on a pharmacokinetic study of homoegonol in rats, homoegonol is almost completely eliminated via metabolism, but no study on its metabolism has been reported in animals and humans. Incubation of homoegonol in human liver microsomes in the presence of the reduced form of nicotinamide adenine dinucleotide phosphate and UDP-glucuronic acid resulted in the formation of five metabolites: 4-O-demethylhomoegonol (M1), hydroxyhomoegonol (M2 and M3), 4-O-demethylhomoegonol glucuronide (M4), and homoegonol glucuronide (M5). We characterized the cytochrome P450 (CYP) and UDP-glucuronosyltransferase (UGT) enzymes responsible for homoegonol metabolism using human liver microsomes, and cDNA-expressed CYP and UGT enzymes. CYP1A2 played a more prominent role than CYP3A4 and CYP2D6 in the 4-O-demethylation of homoegonol to M1. CYP3A4 was responsible for the hydroxylation of homoegonol to M2. The hydroxylation of homoegonol to M3 was insufficient to characterize CYP enzymes. Glucuronidation of homoegonol to M5 was mediated by UGT1A1, UGT1A3, UGT1A4, and UGT2B7 enzymes, whereas M4 was formed from 4-O-demethylhomoegonol by UGT1A1, UGT1A8, UGT1A10, and UGT2B15 enzymes.

  3. Effect of health foods on cytochrome P450-mediated drug metabolism.

    Science.gov (United States)

    Sasaki, Takamitsu; Sato, Yu; Kumagai, Takeshi; Yoshinari, Kouichi; Nagata, Kiyoshi

    2017-01-01

    Health foods have been widely sold and consumed in Japan. There has been an increase in reports of adverse effects in association with the expanding health food market. While health food-drug interactions are a particular concern from the viewpoint of safe and effective use of health foods, information regarding such interactions is limited owing to the lack of established methods to assess the effects of health food products on drug metabolism. We therefore developed cells that mimicked the activities of cytochrome P450 1A2 (CYP1A2), CYP2C9, CYP2C19, CYP2D6, and CYP3A4, which strongly contribute to drug metabolism in human hepatocytes, and established a system to assess the inhibitory activity of health foods toward P450-mediated metabolism. We simultaneously infected HepG2 cells with five P450-expressing adenoviruses (Ad-CYP1A2, Ad-CYP2C9, Ad-CYP2C19, Ad-CYP2D6, and Ad-CYP3A4) to mimic the activity levels of these P450s in human hepatocytes, and named them Ad-P450 cells. The activity levels of P450s in Ad-P450 cells and human hepatocytes were calculated via simultaneous liquid chromatography/tandem mass spectrometry analysis utilizing a P450 substrate cocktail. We established Ad-P450 cells mimicking the activity levels of CYP1A2, CYP2C9, CYP2C19, CYP2D6, and CYP3A4 in human hepatocytes. We determined the Km values of P450 substrates and IC50 values of P450 inhibitors in Ad-P450 cells. These values were approximately equivalent to those obtained in previous studies. We investigated the inhibitory effects of 172 health foods that were recently in circulation in Japan on P450-mediated metabolism using Ad-P450 cells. Of the 172 health foods, five products (two products having dietary effects, one turmeric-based product, one collagen-based product, and one propolis-containing product) simultaneously inhibited the five P450s by more than 50%. Another 29 products were also confirmed to inhibit one or more P450s. We established a comprehensive assessment system to

  4. Urinary mutagenicity, CYP1A2 and NAT2 activity in textile industry workers.

    Science.gov (United States)

    Fanlo, Ana; Sinuès, Blanca; Mayayo, Esteban; Bernal, Luisa; Soriano, Antonia; Martínez-Jarreta, Begoña; Martínez-Ballarín, Enrique

    2004-11-01

    The two major causes of bladder cancer have been recognised to be cigarette smoke and occupational exposure to arylamines. These compounds are present both in tobacco smoke and in the dyes used in textile production. Aromatic amines suffer oxidative metabolism via P450 cytochrome CYP1A2, and detoxification by the polymorphic NAT2. The aim of the present work was to assess the association between occupational-derived exposure to mutagens and CYP1A2 or NAT2 activity. This cross-sectional study included 117 textile workers exposed to dyes and 117 healthy controls. The urinary mutagenicity was determined in 24 h urine using TA98 Salmonella typhimurium strain with microsomal activation S9 (MIS9) or incubation with beta-glucuronidase (MIbeta). Urinary caffeine metabolite ratios: AFMU+1X+1U/17U, and AFMU/AFMU+1X+1U were calculated to assess CYP1A2 and NAT2 activities, respectively. The results show that workers present a strikingly higher urine mutagenicity than controls (p0.05) was compared, and the urinary mutagenicity was not significantly associated with the CYP1A2 activity marker (r=0.04 and r=-0.01 for MIS9 and MIbeta, respectively). This study clearly indicates the need for further protective policies to minimise exposure to the lowest feasible limit in order to avoid unnecessary risks.

  5. Hepatic cytochrome P450 activity, abundance, and expression throughout human development

    Energy Technology Data Exchange (ETDEWEB)

    Sadler, Natalie C.; Nandhikonda, Premchendar; Webb-Robertson, Bobbie-Jo M.; Ansong, Charles; Anderson, Lindsey N.; Smith, Jordan N.; Corley, Richard A.; Wright, Aaron T.

    2016-07-01

    Cytochrome P450s are Phase I metabolic enzymes that play critical roles in the biotransformation of endogenous compounds and xenobiotics. The expression and activity of P450 enzymes can vary considerably throughout human development, especially when comparing fetal development to neonates, children, and adults. In an effort to develop a more comprehensive understanding of the ontogeny of P450 expression and activity we employed a multi-omic characterization of P450 transcript expression, protein abundance, and functional activity. To quantify the functional activity of individual P450s we employ activity-based protein profiling, which uses modified mechanism-based inhibitors of P450s as chemical probes, in tandem with proteomic analyses to quantify activity. Our results reveal life-stage-dependent variability in P450 expression, abundance, and activity throughout human development and frequent discordant relationships between expression and activity. The results were used to distribute P450s into three general classes based upon developmental stage of expression and activity. We have significantly expanded the knowledge of P450 ontogeny, particularly at the level of individual P450 activity. We anticipate that our ontogeny results will be useful for enabling predictive therapeutic dosing, and for avoiding potentially adverse and harmful reactions during maturation from both therapeutic drugs and environmental xenobiotics.

  6. Functional characterisation of an engineered multidomain human P450 2E1 by molecular Lego.

    Science.gov (United States)

    Fairhead, Michael; Giannini, Silva; Gillam, Elizabeth M J; Gilardi, Gianfranco

    2005-12-01

    The human cytochrome P450s constitute an important family of monooxygenase enzymes that carry out essential roles in the metabolism of endogenous compounds and foreign chemicals. We present here results of a fusion between a human P450 enzyme and a bacterial reductase that for the first time is shown does not require the addition of lipids or detergents to achieve wild-type-like activities. The fusion enzyme, P450 2E1-BMR, contains the N-terminally modified residues 22-493 of the human P450 2E1 fused at the C-terminus to residues 473-1049 of the P450 BM3 reductase (BMR). The P450 2E1-BMR enzyme is active, self-sufficient and presents the typical marker activities of the native human P450 2E1: the hydroxylation of p-nitrophenol (KM=1.84+/-0.09 mM and kcat of 2.98+/-0.04 nmol of p-nitrocatechol formed per minute per nanomole of P450) and chlorzoxazone (KM=0.65+/-0.08 mM and kcat of 0.95+/-0.10 nmol of 6-hydroxychlorzoxazone formed per minute per nanomole of P450). A 3D model of human P450 2E1 was generated to rationalise the functional data and to allow an analysis of the surface potentials. The distribution of charges on the model of P450 2E1 compared with that of the FMN domain of BMR provides the ground for the understanding of the interaction between the fused domains. The results point the way to successfully engineer a variety of catalytically self-sufficient human P450 enzymes for drug metabolism studies in solution.

  7. Biotransformation of chlorpyrifos and diazinon by human liver microsomes and recombinant human cytochrome P450s (CYP).

    Science.gov (United States)

    Sams, C; Cocker, J; Lennard, M S

    2004-10-01

    The cytochrome P450 (CYP)-mediated biotransformation of the organophosphorothioate insecticides chlorpyrifos and diazinon was investigated. Rates of desulphuration to the active oxon metabolite (chlorpyrifos-oxon and diazinon-oxon) and dearylation to non-toxic hydrolysis products were determined in human liver microsome preparations from five individual donors and in recombinant CYP enzymes. Chlorpyrifos and diazinon underwent desulphuration in human liver microsome with mean Km = 30 and 45 microM and V(max) = 353 and 766 pmol min(-1) mg(-1), respectively. Dearylation of these compounds by human liver microsome proceeded with Km = 12 and 28 microM and V(max) = 653 and 1186 pmol min(-1) mg(-1), respectively. The apparent intrinsic clearance (V(max)/Km) of dearylation was 4.5- and 2.5-fold greater than desulphuration for chlorpyrifos and diazinon, respectively. Recombinant human CYP2B6 possessed the highest desulphuration activity for chlorpyrifos, whereas CYP2C19 had the highest dearylation activity. In contrast, both desulphuration and dearylation of diazinon were catalysed at similar rates, in the rank order CYP2C19 > CYP1A2 > CYP2B6 > CYP3A4. Both organophosphorothioates were more readily detoxified (dearylation) than bioactivated (desulphuration) in all human liver microsome preparations. However, the role of individual CYP enzymes in these two biotransformation pathways varied according to the structure of the organophosphorothioate, which was reflected in different activation/detoxification ratios for chlorpyrifos and diazinon. Variability in activity of individual CYP enzymes may influence interindividual sensitivity to the toxic effects of chlorpyrifos and diazinon.

  8. Inhibitory effect of salvianolate on human cytochrome P450 3A4 in vitro involving a noncompetitive manner.

    Science.gov (United States)

    Qin, Chong-Zhen; Ren, Xian; Zhou, Hong-Hao; Mao, Xiao-Yuan; Liu, Zhao-Qian

    2015-01-01

    Salvianolic acid B (Sal B), which is purified from Danshen, is a popular herb extract. Sal B has anti-oxidative, anti-inflammatory, anti-hypoxic, anti-arteriosclerotic and anti-apoptotic properties. This substance can also ameliorate brain injury or neurodegenerative diseases. The listed drug Salvianolate, which contains a substantial amount of Sal B, has been used for the treatment of coronary heart disease. Our present work aimed to evaluate the inhibitory effect of salvianolate on seven cytochrome P450 isoforms (CYP450), namely, CYP1A2, CYP2A6, CYP2E1, CYP2C9, CYP2C19, CYP2D6 and CYP3A4, in human liver microsomes (HLMs) and recombinant enzymes through high-performance liquid chromatography (HPLC) assay. Salvianolate have a potent inhibitory effect on CYP3A4 activity with IC50 values of 1.438 (HLMs) and 3.582 (recombinant cDNA-expressed CYP3A4) mg/L, respectively. Salvianolate strongly dose, but not time-dependently decreased CYP3A4 activity in HLMs. The typical Lineweaver-Burk plots showed that Salvianolate inhibited CYP3A4 activity noncompetitively, with a Ki value of 2.27 mg/L in HLMs. Other CYP450 isoforms are not markedly affected by Salvianolate. These findings indicate that salvianolate may be involved in potential drug interactions when co-administrated with CYP3A4 substrates.

  9. Mangifera indica L. extract and mangiferin modulate cytochrome P450 and UDP-glucuronosyltransferase enzymes in primary cultures of human hepatocytes.

    Science.gov (United States)

    Rodeiro, Idania; José Gómez-Lechón, M; Perez, Gabriela; Hernandez, Ivones; Herrera, José Alfredo; Delgado, Rene; Castell, José V; Teresa Donato, M

    2013-05-01

    The aqueous stem bark extract of Mangifera indica L. (MSBE) has been reported to have antioxidant, anti-inflammatory and analgesic properties. In previous studies, we showed that MSBE and mangiferin, its main component, lower the activity of some cytochrome P-450 (P450) enzymes in rat hepatocytes and human liver microsomes. In the present study, the effects of MSBE and mangiferin on several P450 enzymes and UDP-glucuronosyltransferases (UGTs) in human-cultured hepatocytes have been examined. After hepatocytes underwent a 48-h treatment with sub-cytotoxic concentrations of the products (50-250 µg/mL), a concentration-dependent decrease of the activity of the five P450 enzymes measured (CYP1A2, 2A6, 2C9, 2D6 and 3A4) was observed. For all the activities, a reduction of at least 50% at the highest concentration (250 µg/mL) was observed. In addition, UGT activities diminished. MSBE considerably reduced UGT1A9 activity (about 60% at 250 µg/mL) and lesser effects on the other UGTs. In contrast, 250 µg/mL mangiferin had greater effects on UGT1A1 and 2B7 than on UGT1A9 (about 55% vs. 35% reduction, respectively). Quantification of specific mRNAs revealed reduced CYP3A4 and 3A5 mRNAs content, and an increase in CYP1A1, CYP1A2, UGT1A1 and UGT1A9 mRNAs. No remarkable effects on the CYP2A6, 2B6, 2C9, 2C19, 2D6 and 2E1 levels were observed. Our results suggest that the activity and/or expression of major P450 and UGT enzymes is modulated by MSBE and that potential herb-drugs interactions could arise after a combined intake of this extract with conventional medicines. Therefore, the potential safety risks of this natural product derived by altering the ADMET properties of co-administered drugs should be examined.

  10. Exploiting the versatility of human cytochrome P450 enzymes: the promise of blue roses from biotechnology.

    Science.gov (United States)

    Gillam, E M; Guengerich, F P

    2001-12-01

    The cytochrome P450 (P450) enzymes involved in drug metabolism are among the most versatile biological catalysts known. A small number of discrete forms of human P450 are capable of catalyzing the monooxygenation of a practically unlimited variety of xenobiotic substrates, with each enzyme showing a more or less wide and overlapping substrate range. This versatility makes P450s ideally suited as starting materials for engineering designer catalysts for industrial applications. In the course of heterologous expression of P450s in bacteria, we observed the unexpected formation of blue pigments. Although this was initially assumed to be an artifact, subsequent work led to the discovery of a new function of P450s in intermediary metabolism and toxicology, new screens for protein engineering, and potential applications in the dye and horticulture industries.

  11. Expression and Characterization of Truncated Recombinant Human Cytochrome P450 2J2

    OpenAIRE

    Park, Hyoung-Goo; Lim, Young-Ran; Han, Songhee; Kim, Donghak

    2014-01-01

    The human cytochrome P450 2J2 catalyzes an epoxygenase reaction to oxidize various fatty acids including arachidonic acid. In this study, three recombinant enzyme constructs of P450 2J2 were heterologously expressed in Escherichia coli and their P450 proteins were successfully purified using a Ni2+-NTA affinity column. Deletion of 34 amino acid residues in N-terminus of P450 2J2 enzyme (2J2-D) produced the soluble enzyme located in the cytosolic fraction. The enzymatic analysis of this trunca...

  12. Human cytochrome P450 enzyme specificity for bioactivation of safrole to the proximate carcinogen 1'-hydroxysafrole

    NARCIS (Netherlands)

    Jeurissen, S.M.F.; Bogaards, J.J.P.; Awad, H.M.; Boersma, M.G.; Brand, W.; Fiamegos, Y.C.; Beek, van T.A.; Alink, G.M.; Sudhölter, E.J.R.; Cnubben, N.H.P.; Rietjens, I.M.C.M.

    2004-01-01

    In the present study, the cytochrome P450 mediated bioactivation of safrole to its proximate carcinogenic metabolite, 1'-hydroxysafrole, has been investigated for the purpose of identifying the human P450 enzymes involved. The 1'-hydroxylation of safrole was characterized in a variety of in vitro te

  13. Human cytochrome P450 oxidation of 5-hydroxythalidomide and pomalidomide, an amino analogue of thalidomide.

    Science.gov (United States)

    Chowdhury, Goutam; Shibata, Norio; Yamazaki, Hiroshi; Guengerich, F Peter

    2014-01-21

    The sedative and antiemetic drug thalidomide [α-(N-phthalimido)glutarimide] was withdrawn in the early 1960s because of its potent teratogenic effects but was approved for the treatment of lesions associated with leprosy in 1998 and multiple myeloma in 2006. The mechanism of teratogenicity of thalidomide still remains unclear, but it is well-established that metabolism of thalidomide is important for both teratogenicity and cancer treatment outcome. Thalidomide is oxidized by various cytochrome P450 (P450) enzymes, the major one being P450 2C19, to 5-hydroxy-, 5'-hydroxy-, and dihydroxythalidomide. We previously reported that P450 3A4 oxidizes thalidomide to the 5-hydroxy and dihydroxy metabolites, with the second oxidation step involving a reactive intermediate, possibly an arene oxide, that can be trapped by glutathione (GSH) to GSH adducts. We now show that the dihydroxythalidomide metabolite can be further oxidized to a quinone intermediate. Human P450s 2J2, 2C18, and 4A11 were also found to oxidize 5-hydroxythalidomide to dihydroxy products. Unlike P450s 2C19 and 3A4, neither P450 2J2, 2C18, nor 4A11 oxidized thalidomide itself. A recently approved amino analogue of thalidomide, pomalidomide (CC-4047, Actimid), was also oxidized by human liver microsomes and P450s 2C19, 3A4, and 2J2 to the corresponding phthalimide ring-hydroxylated product.

  14. Functional analysis of human cytochrome P450 21A2 variants involved in congenital adrenal hyperplasia

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Chunxue; Pallan, Pradeep S.; Zhang, Wei; Lei, Li; Yoshimoto, Francis K.; Waterman, Michael R.; Egli, Martin; Guengerich, F. Peter (Vanderbilt-MED)

    2017-05-24

    Cytochrome P450 (P450, CYP) 21A2 is the major steroid 21-hydroxylase, converting progesterone to 11-deoxycorticosterone and 17α-hydroxyprogesterone (17α-OH-progesterone) to 11-deoxycortisol. More than 100 CYP21A2 variants give rise to congenital adrenal hyperplasia (CAH). We previously reported a structure of WT human P450 21A2 with bound progesterone and now present a structure bound to the other substrate (17α-OH-progesterone). We found that the 17α-OH-progesterone- and progesterone-bound complex structures are highly similar, with only some minor differences in surface loop regions. Twelve P450 21A2 variants associated with either salt-wasting or nonclassical forms of CAH were expressed, purified, and analyzed. The catalytic activities of these 12 variants ranged from 0.00009% to 30% of WT P450 21A2 and the extent of heme incorporation from 10% to 95% of the WT. Substrate dissociation constants (Ks) for four variants were 37–13,000-fold higher than for WT P450 21A2. Cytochrome b5, which augments several P450 activities, inhibited P450 21A2 activity. Similar to the WT enzyme, high noncompetitive intermolecular kinetic deuterium isotope effects (≥ 5.5) were observed for all six P450 21A2 variants examined for 21-hydroxylation of 21-d3-progesterone, indicating that C–H bond breaking is a rate-limiting step over a 104-fold range of catalytic efficiency. Using UV-visible and CD spectroscopy, we found that P450 21A2 thermal stability assessed in bacterial cells and with purified enzymes differed among salt-wasting- and nonclassical-associated variants, but these differences did not correlate with catalytic activity. Our in-depth investigation of CAH-associated P450 21A2 variants reveals critical insight into the effects of disease-causing mutations on this important enzyme.

  15. The cytochrome P450 superfamily: biochemistry, evolution and drug metabolism in humans.

    Science.gov (United States)

    Danielson, P B

    2002-12-01

    Cytochrome p450s comprise a superfamily of heme-thiolate proteins named for the spectral absorbance peak of their carbon-monoxide-bound species at 450 nm. Having been found in every class of organism, including Archaea, the p450 superfamily is believed to have originated from an ancestral gene that existed over 3 billion years ago. Repeated gene duplications have subsequently given rise to one of the largest of multigene families. These enzymes are notable both for the diversity of reactions that they catalyze and the range of chemically dissimilar substrates upon which they act. Cytochrome p450s support the oxidative, peroxidative and reductive metabolism of such endogenous and xenobiotic substrates as environmental pollutants, agrochemicals, plant allelochemicals, steroids, prostaglandins and fatty acids. In humans, cytochrome p450s are best know for their central role in phase I drug metabolism where they are of critical importance to two of the most significant problems in clinical pharmacology: drug interactions and interindividual variability in drug metabolism. Recent advances in our understanding of cytochrome p450-mediated drug metabolism have been accelerated as a result of an increasing emphasis on functional genomic approaches to p450 research. While human cytochrome p450 databases have swelled with a flood of new human sequence variants, however, the functional characterization of the corresponding gene products has not kept pace. In response researchers have begun to apply the tools of proteomics as well as homology-based and ab initio modeling to salient questions of cytochrome p450 structure/function. This review examines the latest advances in our understanding of human cytochrome p450s.

  16. CYP2C subfamily, primarily CYP2C9, catalyses the enantioselective demethylation of the endocrine disruptor pesticide methoxychlor in human liver microsomes: use of inhibitory monoclonal antibodies in P450 identification.

    Science.gov (United States)

    Hu, Y; Krausz, K; Gelboin, H V; Kupfer, D

    2004-02-01

    1. The endocrine disruptor pesticide methoxychlor undergoes O-demethylation by mammalian liver microsomes forming chiral mono-phenolic (1,1,1-trichloro-2-(4-hydroxyphenyl)-2-(4-methoxyphenyl)ethane, i.e. mono-OH-M) and achiral bis-phenolic oestrogenic metabolites. Human liver microsomes (HLM) generated primarily the S-mono-OH-M. 2. Inhibitory monoclonal antibodies (MAb) identified those P450s catalysing the enantioselective O-demethylation of methoxychlor. In HLM, O-demethylation was inhibited by MAb anti-2C9 (30-40%), diminishing the per cent of S-mono-OH-M from about 80 to 55-60%. MAb anti-CYP1A2, 2A6, 2B6, 2C8, 2C19, 2D6 and 3A4 did not affect the demethylation rate in HLM. Nevertheless, MAb anti-CYP1A2 decreased the formation of R-mono-OH-M from 21-23 to 10-17%, indicating that CYP1A2 exhibits a role in generating the R-enantiomer. 3. Among cDNA-expressed human P450s (supersomes), CYP2C19 was the most active in demethylation, but in HLM, CYP2C19 appeared inactive (no inhibition by MAb anti-CYP2C19). There was a substantial difference in the per cent inhibition of demethylation by MAb anti-CYP2C9 and anti-rat CYP2C (MAb inhibiting all human CYP2C forms) and in altering the enantioselectivity, suggesting that demethylation by combined CYP2C8, 2C18 and 2C19 was significant (20-30%). 4. Polymorphism of methoxychlor demethylation was examined with supersomes and HLM-expressing CYP2C9 allelic variants. CYP2C9*1 and 2C9*2 were highly active; however, CYP2C9*3 appeared inactive.

  17. Aromatic hydroxylation of salicylic acid and aspirin by human cytochromes P450.

    Science.gov (United States)

    Bojić, Mirza; Sedgeman, Carl A; Nagy, Leslie D; Guengerich, F Peter

    2015-06-20

    Aspirin (acetylsalicylic acid) is a well-known and widely-used analgesic. It is rapidly deacetylated to salicylic acid, which forms two hippuric acids-salicyluric acid and gentisuric acid-and two glucuronides. The oxidation of aspirin and salicylic acid has been reported with human liver microsomes, but data on individual cytochromes P450 involved in oxidation is lacking. In this study we monitored oxidation of these compounds by human liver microsomes and cytochrome P450 (P450) using UPLC with fluorescence detection. Microsomal oxidation of salicylic acid was much faster than aspirin. The two oxidation products were 2,5-dihydroxybenzoic acid (gentisic acid, documented by its UV and mass spectrum) and 2,3-dihydroxybenzoic acid. Formation of neither product was inhibited by desferrioxamine, suggesting a lack of contribution of oxygen radicals under these conditions. Although more liphophilic, aspirin was oxidized less efficiently, primarily to the 2,5-dihydroxy product. Recombinant human P450s 2C8, 2C9, 2C19, 2D6, 2E1, and 3A4 all catalyzed the 5-hydroxylation of salicylic acid. Inhibitor studies with human liver microsomes indicated that all six of the previously mentioned P450s could contribute to both the 5- and 3-hydroxylation of salicylic acid and that P450s 2A6 and 2B6 have contributions to 5-hydroxylation. Inhibitor studies indicated that the major human P450 involved in both 3- and 5-hydroxylation of salicylic acid is P450 2E1.

  18. Inhibitory effects of seven components of danshen extract on catalytic activity of cytochrome P450 enzyme in human liver microsomes.

    Science.gov (United States)

    Qiu, Furong; Zhang, Rong; Sun, Jianguo; Jiye, A; Hao, Haiping; Peng, Ying; Ai, Hua; Wang, Guangji

    2008-07-01

    The potential for herb-drug interactions has recently received greater attention worldwide, considering the fact that the use of herbal products becomes more and more widespread. The goal of this work was to examine the potential for the metabolism-based drug interaction arising from seven active components (danshensu, protocatechuic aldehyde, protocatechuic acid, salvianolic acid B, tanshinone I, tanshinone IIA, and cryptotanshinone) of danshen extract. Probe substrates of cytochrome P450 enzymes were incubated in human liver microsomes (HLMs) with or without each component of danshen extract. IC(50) and K(i) values were estimated, and the types of inhibition were determined. Among the seven components of danshen extract, tanshinone I, tanshinone IIA, and cryptotanshinone were potent competitive inhibitors of CYP1A2 (K(i) = 0.48, 1.0, and 0.45 microM, respectively); danshensu was a competitive inhibitor of CYP2C9 (K(i) = 35 microM), and cryptotanshinone was a moderate mixed-type inhibitor of CYP2C9 (K(i) = 8 microM); cryptotanshinone inhibited weakly and in mixed mode against CYP2D6 activity (K(i) = 68 microM), and tanshinone I was a weak inhibitor of CYP2D6 (IC(50) = 120 microM); and protocatechuic aldehyde was a weak inhibitor of CYP3A4 (IC(50) = 130 and 160 microM for midazolam and testosterone, respectively). These findings provided some useful information for safe and effective use of danshen preparations in clinical practice. Our data indicated that it was necessary to study the in vivo interactions between drugs and pharmaceuticals with danshen extract.

  19. Phenotyping studies to assess the effects of phytopharmaceuticals on in vivo activity of main human cytochrome p450 enzymes.

    Science.gov (United States)

    Zadoyan, Gregor; Fuhr, Uwe

    2012-09-01

    The extensive use of herbal drugs and their multiple components and modes of action suggests that they may also cause drug interactions by changing the activity of human cytochrome P450 enzymes. The purpose of the present review is to present the available data for the top 14 herbal drug sales in the U. S. Studies describing the effects of herbal drugs on phenotyping substrates for individual CYPs were identified by a comprehensive MEDLINE search. Drugs included Allium sativum (Liliaceae), Echinacea purpurea (Asteraceae), Serenoa repens (Arecaceae), Ginkgo biloba (Ginkgoaceae), Vaccinium macrocarpon (Ericaceae), Glycine max (Fabaceae), Panax ginseng (Araliaceae), Actea racemosa (Ranunculaceae), Hypericum perforatum (Hypericaceae), Silybum marianum (Asteraceae), Camellia sinensis (Theaceae), Valeriana officinalis (Valerianaceae), Piper methysticum (Piperaceae), and Hydrastis canadensis (Ranunculaceae) preparations. We identified 70 clinical studies in 69 publications. The majority of the herbal drugs appeared to have no clear effects on most of the CYPs examined. If there was an effect, there was mild inhibition in almost all cases, as seen with garlic or kava effects on CYP2E1 and with soybean components on CYP1A2. The most pronounced effects were induction of CYP3A and other CYPs by St. John's wort and the inhibitory effect of goldenseal on CYP3A and CYP2D6, both being borderline between mild and moderate in magnitude. With the exceptions of St.John's wort and goldenseal, the information currently available suggests that concomitant intake of the herbal drugs addressed here is not a major risk for drugs that are metabolized by CYPs.

  20. Target Proteins in Human Autoimmunity: Cytochromes P450 and Udp-Glycoronosyltransferases

    Directory of Open Access Journals (Sweden)

    Petra Obermayer-Straub

    2000-01-01

    Full Text Available Cytochromes P450 (CYPs and UDP-glucuronosyltransferases (UGTs are targets of autoantibodies in several hepatic and extrahepatic autoimmune diseases. Autoantibodies directed against hepatic CYPs and UGTs were first detected by indirect immunofluorescence as antiliver and/or kidney microsomal antibodies. In autoimmune hepatitis (AIH type 2, liver and/or kidney microsomal (LKM type 1 autoantibodies are detected and are directed against CYP2D6. About 10% of AIH-2 sera further contain LKM-3 autoantibodies directed against family 1 UGTs. Chronic infections by hepatitis C virus and hepatitis delta virus may induce several autoimmune phenomena, and multiple autoantibodies are detected. Anti-CYP2D6 autoantibodies are detected in up to 4% of patients with chronic hepatitis C, and anti-CYP2A6 autoantibodies are detected in about 2% of these patients. In contrast, 14% of patients with chronic hepatitis delta virus infections generate anti-UGT autoantibodies. In a small minority of patients, certain drugs are known to induce immune-mediated, idiosyncratic drug reactions, also known as ’drug-induced hepatitis’. Drug-induced hepatitis is often associated with autoantibodies directed against hepatic CYPs or other hepatic proteins. Typical examples are tienilic acid-induced hepatitis with anti-CYP2C9, dihydralazine hepatitis with anti-CYP1A2, halothane hepatitis with anti-CYP2E1 and anticonvulsant hepatitis with anti-CYP3A. Recent data suggest that alcoholic liver disease may be induced by mechanisms similar to those that are active in drug-induced hepatitis. Autoantibodies directed against several CYPs are further detected in sera from patients with the autoimmune polyglandular syndrome type 1. Patients with autoimmune polyglandular syndrome type 1 with hepatitis often develop anti-CYP1A2; patients with adrenal failure develop anti-CYP21, anti- CYP11A1 or CYP17; and patients with gonadal failure develop anti-CYP11A1 or CYP17. In idiopathic Addison disease

  1. 3D-QSAR methods on the basis of ligand-receptor complexes. Application of COMBINE and GRID/GOLPE methodologies to a series of CYP1A2 ligands

    Science.gov (United States)

    Lozano, Juan José; Pastor, Manuel; Cruciani, Gabriele; Gaedt, Katrin; Centeno, Nuria B.; Gago, Federico; Sanz, Ferran

    2000-05-01

    Many heterocyclic amines (HCA) present in cooked food exert a genotoxic activity when they are metabolised (N-oxidated) by the human cytochrome P450 1A2 (CYP1A2h). In order to rationalize the observed differences in activity of this enzyme on a series of 12 HCA, 3D-QSAR methods were applied on the basis of models of HCA-CYP1A2h complexes. The CYP1A2h enzyme model has been previously reported and was built by homology modeling based on cytochrome P450 BM3. The complexes were automatically generated applying the AUTODOCK software and refined using AMBER. A COMBINE analysis on the complexes identified the most important enzyme-ligand interactions that account for the differences in activity within the series. A GRID/GOLPE analysis was then performed on just the ligands, in the conformations and orientations found in the modeled complexes. The results from both methods were concordant and confirmed the advantages of incorporating structural information from series of ligand-receptor complexes into 3D-QSAR methodologies.

  2. Influence of Sulforaphane Metabolites on Activities of Human Drug-Metabolizing Cytochrome P450 and Determination of Sulforaphane in Human Liver Cells.

    Science.gov (United States)

    Vanduchova, Alena; Tomankova, Veronika; Anzenbacher, Pavel; Anzenbacherova, Eva

    2016-12-01

    The influence of metabolites of sulforaphane, natural compounds present in broccoli (Brassica oleracea var. botrytis italica) and in other cruciferous vegetables, on drug-metabolizing cytochrome P450 (CYP) enzymes in human liver microsomes and possible entry of sulforaphane into human hepatic cells were investigated. Metabolites studied are compounds derived from sulforaphane by the mercapturic acid pathway (conjugation with glutathione and by following reactions), namely sulforaphane glutathione and sulforaphane cysteine conjugates and sulforaphane-N-acetylcysteine. Their possible effect on four drug-metabolizing CYP enzymes, CYP3A4 (midazolam 1'-hydroxylation), CYP2D6 (bufuralol 1'-hydroxylation), CYP1A2 (7-ethoxyresorufin O-deethylation), and CYP2B6 (7-ethoxy-4-(trifluoromethyl)coumarin O-deethylation), was tested. Inhibition of four prototypical CYP activities by sulforaphane metabolites was studied in pooled human liver microsomes. Sulforaphane metabolites did not considerably affect biological function of drug-metabolizing CYPs in human liver microsomes except for CYP2D6, which was found to be inhibited down to 73-78% of the original activity. Analysis of the entry of sulforaphane into human hepatocytes was done by cell disruption by sonication, methylene chloride extraction, and modified high-performance liquid chromatography method. The results have shown penetration of sulforaphane into the human hepatic cells.

  3. Kinetic analysis of lauric acid hydroxylation by human cytochrome P450 4A11.

    Science.gov (United States)

    Kim, Donghak; Cha, Gun-Su; Nagy, Leslie D; Yun, Chul-Ho; Guengerich, F Peter

    2014-10-07

    Cytochrome P450 (P450) 4A11 is the only functionally active subfamily 4A P450 in humans. P450 4A11 catalyzes mainly ω-hydroxylation of fatty acids in liver and kidney; this process is not a major degradative pathway, but at least one product, 20-hydroxyeicosatetraenoic acid, has important signaling properties. We studied catalysis by P450 4A11 and the issue of rate-limiting steps using lauric acid ω-hydroxylation, a prototypic substrate for this enzyme. Some individual reaction steps were studied using pre-steady-state kinetic approaches. Substrate and product binding and release were much faster than overall rates of catalysis. Reduction of ferric P450 4A11 (to ferrous) was rapid and not rate-limiting. Deuterium kinetic isotope effect (KIE) experiments yielded low but reproducible values (1.2-2) for 12-hydroxylation with 12-(2)H-substituted lauric acid. However, considerable "metabolic switching" to 11-hydroxylation was observed with [12-(2)H3]lauric acid. Analysis of switching results [Jones, J. P., et al. (1986) J. Am. Chem. Soc. 108, 7074-7078] and the use of tritium KIE analysis with [12-(3)H]lauric acid [Northrop, D. B. (1987) Methods Enzymol. 87, 607-625] both indicated a high intrinsic KIE (>10). Cytochrome b5 (b5) stimulated steady-state lauric acid ω-hydroxylation ∼2-fold; the apoprotein was ineffective, indicating that electron transfer is involved in the b5 enhancement. The rate of b5 reoxidation was increased in the presence of ferrous P450 mixed with O2. Collectively, the results indicate that both the transfer of an electron to the ferrous·O2 complex and C-H bond-breaking limit the rate of P450 4A11 ω-oxidation.

  4. Potential inhibition of cytochrome P450 3A4 by propofol in human primary hepatocytes

    Institute of Scientific and Technical Information of China (English)

    Li-Qun Yang; Wei-Feng Yu; Yun-Fei Cao; Bin Gong; Qing Chang; Guang-Shun Yang

    2003-01-01

    AIM: Hepatic cytochrome P450 isoenzymes constitute a superfamily of hemoproteins that play a major role in the metabolism of endogenous compounds and in the detoxification of xenobiotic molecules. P450 3A4 is one of the most important forms in human being, and mediates the metabolism of around 70% of therapeutic drugs and endogenous compounds. Propofol, a widely used intravenous anesthetic drug, is known to inhibit cytochrome P450activities in isolated rat hepatocytes. The goal of this study was to evaluate the potential efficacy of propofol on P4503A4 in a dose-dependent manner to understand its drugdrug interaction.METHODS: Hepatocytes were isolated from liver specimens from hepatic angioma patients undergone hepatic surgery.Primary incubated hepatocytes were treated with 0, 0.01,0.05, 0.1, 0.5, and 1.0 mM propofol for 24 hours. P450 3A4activity was measured with Nash′s colorimetry. The protein expression was assessed by Western blot analysis.RESULTS: A dose-dependent inhibitory effect of propofol was observed in cytochrome P450 3A4 activity. A minimal dosage of propofol (0.01 mM) induced a significant inhibition of P450 3A4 activity, although its regular dosages (0.01-0.1mM) showed no inhibitory effect on the cellular protein expression of P450 3A4.CONCLUSION: Propofol may be a potential CYP3A4 inhibitor as this anesthetic can inhibit isoenzyme activity significantly and reduce the metabolic rate of CYP3A4 substrates. This inhibition occurs at post-expression level, and concentration of propofol used clinically does not affect CYP3A4 protein expression. propofol may thus induce drug interaction of cytochrome P450 3A4 activity at the dosage used clinically.

  5. The binding sites on human heme oxygenase-1 for cytochrome p450 reductase and biliverdin reductase.

    Science.gov (United States)

    Wang, Jinling; de Montellano, Paul R Ortiz

    2003-05-30

    Human heme oxygenase-1 (hHO-1) catalyzes the NADPH-cytochrome P450 reductase-dependent oxidation of heme to biliverdin, CO, and free iron. The biliverdin is subsequently reduced to bilirubin by biliverdin reductase. Earlier kinetic studies suggested that biliverdin reductase facilitates the release of biliverdin from hHO-1 (Liu, Y., and Ortiz de Montellano, P. R. (2000) J. Biol. Chem. 275, 5297-5307). We have investigated the binding of P450 reductase and biliverdin reductase to truncated, soluble hHO-1 by fluorescence resonance energy transfer and site-specific mutagenesis. P450 reductase and biliverdin reductase bind to truncated hHO-1 with Kd = 0.4 +/- 0.1 and 0.2 +/- 0.1 microm, respectively. FRET experiments indicate that biliverdin reductase and P450 reductase compete for binding to truncated hHO-1. Mutation of surface ionic residues shows that hHO-1 residues Lys18, Lys22, Lys179, Arg183, Arg198, Glu19, Glu127, and Glu190 contribute to the binding of cytochrome P450 reductase. The mutagenesis results and a computational analysis of the protein surfaces partially define the binding site for P450 reductase. An overlapping binding site including Lys18, Lys22, Lys179, Arg183, and Arg185 is similarly defined for biliverdin reductase. These results confirm the binding of biliverdin reductase to hHO-1 and define binding sites of the two reductases.

  6. Repurposing Resveratrol and Fluconazole To Modulate Human Cytochrome P450-Mediated Arachidonic Acid Metabolism.

    Science.gov (United States)

    El-Sherbeni, Ahmed A; El-Kadi, Ayman O S

    2016-04-04

    Cytochrome P450 (P450) enzymes metabolize arachidonic acid (AA) to several biologically active epoxyeicosatrienoic acids (EETs) and hydroxyeicosatetraenoic acids (HETEs). Repurposing clinically-approved drugs could provide safe and readily available means to control EETs and HETEs levels in humans. Our aim was to determine how to significantly and selectively modulate P450-AA metabolism in humans by clinically-approved drugs. Liquid chromatography-mass spectrometry was used to determine the formation of 15 AA metabolites by human recombinant P450 enzymes, as well as human liver and kidney microsomes. CYP2C19 showed the highest EET-forming activity, while CYP1B1 and CYP2C8 showed the highest midchain HETE-forming activities. CYP1A1 and CYP4 showed the highest subterminal- and 20-HETE-forming activity, respectively. Resveratrol and fluconazole produced the most selective and significant modulation of hepatic P450-AA metabolism, comparable to investigational agents. Monte Carlo simulations showed that 90% of human population would experience a decrease by 6-22%, 16-39%, and 16-35% in 16-, 18-, and 20-HETE formation, respectively, after 2.5 g daily of resveratrol, and by 22-31% and 14-23% in 8,9- and 14,15-EET formation after 50 mg of fluconazole. In conclusion, clinically-approved drugs can provide selective and effective means to modulate P450-AA metabolism, comparable to investigational drugs. Resveratrol and fluconazole are good candidates to be repurposed as new P450-based treatments.

  7. Human Cytochrome P450 Enzymes of Importance for the Bioactivation of Methyleugenol to the Proximate Carcinogen 1'-Hydroxymethyleugenol

    NARCIS (Netherlands)

    Jeurissen, S.M.F.; Bogaards, J.J.P.; Boersma, M.G.; Horst, ter J.P.F.; Awad, H.M.; Fiamegos, Y.C.; Beek, van T.A.; Alink, G.M.; Sudhölter, E.J.R.; Cnubben, N.H.P.; Rietjens, I.M.C.M.

    2006-01-01

    In vitro studies were performed to elucidate the human cytochrome P450 enzymes involved in the bioactivation of methyleugenol to its proximate carcinogen 1'-hydroxymethyleugenol. Incubations with Supersomes, expressing individual P450 enzymes to a high level, revealed that P450 1A2, 2A6, 2C9, 2C19,

  8. Human cytochrome P450 enzymes of importance for the bioactivation of methyleugenol to the proximate carcinogen 1′-hydroxymethyleugenol

    NARCIS (Netherlands)

    Jeurissen, S.M.F.; Bogaards, J.J.P.; Boersma, M.G.; Horst, J.P.F. ter; Awad, H.M.; Fiamegos, Y.C.; Beek, T.A. van; Alink, G.M.; Sudhölter, E.J.R.; Cnubben, N.H.P.; Rietjens, I.M.C.M.

    2006-01-01

    In vitro studies were performed to elucidate the human cytochrome P450 enzymes involved in the bioactivation of methyleugenol to its proximate carcinogen 1′-hydroxymethyleugenol. Incubations with Supersomes, expressing individual P450 enzymes to a high level, revealed that P450 1A2, 2A6, 2C9, 2C19,

  9. Phytoremediation of the organic Xenobiotic simazine by p450-1a2 transgenic Arabidopsis thaliana plants.

    Science.gov (United States)

    Azab, Ehab; Hegazy, Ahmad K; El-Sharnouby, Mohamed E; Abd Elsalam, Hassan E

    2016-01-01

    The potential use of human P450-transgenic plants for phytoremediation of pesticide contaminated soils was tested in laboratory and greenhouse experiments. The transgenic P450 CYP1A2 gene Arabidopsis thaliana plants metabolize number of herbicides, insecticides and industrial chemicals. The P450 isozymes CYP1A2 expressed in A. thaliana were examined regarding the herbicide simazine (SIM). Transgenic A. thaliana plants expressing CYP1A2 gene showed significant resistance to SIM supplemented either in plant growth medium or sprayed on foliar parts. The results showed that SIM produces harmful effect on both rosette diameter and primary root length of the wild type (WT) plants. In transgenic A. thaliana lines, the rosette diameter and primary root length were not affected by SIM concentrations used in this experiment. The results indicate that CYP1A2 can be used as a selectable marker for plant transformation, allowing efficient selection of transgenic lines in growth medium and/or in soil-grown plants. The transgenic A. thaliana plants exhibited a healthy growth using doses of up to 250 μmol SIM treatments, while the non-transgenic A. thaliana plants were severely damaged with doses above 50 μmol SIM treatments. The transgenic A. thaliana plants can be used as phytoremediator of environmental SIM contaminants.

  10. In vitro metabolism of a novel synthetic cannabinoid, EAM-2201, in human liver microsomes and human recombinant cytochrome P450s.

    Science.gov (United States)

    Kim, Ju Hyun; Kim, Hee Seung; Kong, Tae Yeon; Lee, Joo Young; Kim, Jin Young; In, Moon Kyo; Lee, Hye Suk

    2016-02-05

    In vitro metabolism of a new synthetic cannabinoid, EAM-2201, has been investigated with human liver microsomes and major cDNA-expressed cytochrome P450 (CYP) isozymes using liquid chromatography-high resolution mass spectrometry (LC-HRMS). Incubation of EAM-2201 with human liver microsomes in the presence of NADPH resulted in the formation of 37 metabolites, including nine hydroxy-EAM-2201 (M1-M9), five dihydroxy-EAM-2201 (M10-M14), dihydrodiol-EAM-2201 (M15), oxidative defluorinated EAM-2201 (M16), two hydroxy-M16 (M17 and M18), three dihydroxy-M16 (M19-M21), N-dealkyl-EAM-2201 (M22), two hydroxy-M22 (M23 and M24), dihydroxy-M22 (M25), EAM-2201 N-pentanoic acid (M26), hydroxy-M26 (M27), dehydro-EAM-2201 (M28), hydroxy-M28 (M29), seven dihydroxy-M28 (M30-M36), and oxidative defluorinated hydroxy-M28 (M37). Multiple CYPs, including CYP1A2, 2B6, 2C8, 2C9, 2C19, 2D6, 2J2, 3A4, and 3A5, were involved in the metabolism of EAM-2201. In conclusion, EAM-2201 is extensively metabolized by CYPs and its metabolites can be used as an indicator of EAM-2201 abuse.

  11. Pungent ginger components modulates human cytochrome P450 enzymes in vitro

    OpenAIRE

    Li, Mian; Chen, Pei-zhan; Yue, Qing-xi; Jing-quan LI; Chu, Rui-Ai; Zhang, Wei; Wang, Hui

    2013-01-01

    Aim: Ginger rhizome is used worldwide as a spicy flavor agent. This study was designed to explore the potential effects of pungent ginger components, 6-, 8-, and 10-gingerol, on human cytochrome P450 (CYP450) enzymes that are responsible for the metabolism of many prescription drugs. Methods: The activities of human CYP2C9, CYP2C19, CYP2D6, and CYP3A4 were analyzed using Vivid P450 assay kits. The mRNA expression of CYP3A4 in human hepatocellular carcinoma cell line HepG2 was measured using q...

  12. In vitro inhibitory effects of asiaticoside and madecassoside on human cytochrome P450.

    Science.gov (United States)

    Winitthana, T; Niwattisaiwong, N; Patarapanich, C; Tantisira, M H; Lawanprasert, S

    2011-06-01

    The inhibitory effects and types of inhibition of asiaticoside and madecassoside on human CYPs were studied in vitro using recombinant human CYPs. The median inhibitory concentrations (IC50) of asiaticoside and madecassoside were determined for CYP1A2, CYP2C9, CYP2C19, CYP2D6, CYP2E1 and CYP3A4. Asiaticoside inhibited CYP2C19 (IC50 = 412.68 ± 15.44 μM) and CYP3A4 (IC50=343.35 ± 29.35 μM). Madecassoside also inhibited CYP2C19 (IC50 = 539.04 ± 14.18 μM) and CYP3A4 (IC50 = 453.32 ± 39.33 μM). Asiaticoside and madecassoside had no effect on the activities of CYP1A2, CYP2C9 and CYP2D6 and CYP2E1. Assessment of mechanism-based inhibition and the type of inhibition were performed for asiaticoside and madecassoside with CYP2C19 and CYP3A4. These results suggested that madecassoside is a mechanism-based inhibitor of CYP2C19 and CYP3A4. Assessment of mechanism-based inhibition by asiaticoside was limited by its low solubility. Asiaticoside exhibited non-competitive inhibition of CYP2C19 (Ki=385.24 ± 8.75 μM) and CYP3A4 (Ki = 535.93 ± 18.99 μM). Madecassoside also showed non-competitive inhibition of CYP2C19 (Ki = 109.62 ± 6.14 μM) and CYP3A4 (Ki = 456.84 ± 16.43 μM). These results suggest that asiaticoside and madecassoside could cause drug-drug interactions via inhibition of CYP2C19 and CYP3A4. An in vivo study is needed to examine this further.

  13. Motion and flexibility in human cytochrome p450 aromatase.

    Directory of Open Access Journals (Sweden)

    Wenhua Jiang

    Full Text Available The crystal structures of human placental aromatase in complex with the substrate androstenedione and exemestane have revealed an androgen-specific active site and the structural basis for higher order organization. However, X-ray structures do not provide accounts of movements due to short-range fluctuations, ligand binding and protein-protein association. In this work, we conduct normal mode analysis (NMA revealing the intrinsic fluctuations of aromatase, deduce the internal modes in membrane-free and membrane-integrated monomers as well as the intermolecular modes in oligomers, and propose a quaternary organization for the endoplasmic reticulum (ER membrane integration. Dynamics of the crystallographic oligomers from NMA is found to be in agreement with the isotropic thermal factors from the X-ray analysis. Calculations of the root mean square fluctuations of the C-alpha atoms from their equilibrium positions confirm that the rigid-core structure of aromatase is intrinsic regardless of the changes in steroid binding interactions, and that aromatase self-association does not deteriorate the rigidity of the catalytic cleft. Furthermore, NMA on membrane-integrated aromatase shows that the internal modes in all likelihood contribute to breathing of the active site access channel. The collective intermolecular hinge bending and twisting modes provide the flexibility in the quaternary association necessary for membrane integration of the aromatase oligomers. Taken together, fluctuations of the active site, the access channel, and the heme-proximal cavity, and a dynamic quaternary organization could all be essential components of the functional aromatase in its role as an ER membrane-embedded steroidogenic enzyme.

  14. Engineering human cytochrome P450 enzymes into catalytically self-sufficient chimeras using molecular Lego.

    Science.gov (United States)

    Dodhia, Vikash Rajnikant; Fantuzzi, Andrea; Gilardi, Gianfranco

    2006-10-01

    The membrane-bound human cytochrome P450s have essential roles in the metabolism of endogenous compounds and drugs. Presented here are the results on the construction and characterization of three fusion proteins containing the N-terminally modified human cytochrome P450s CYP2C9, CY2C19 and CYP3A4 fused to the soluble NADPH-dependent oxidoreductase domain of CYP102A1 from Bacillus megaterium. The constructs, CYP2C9/BMR, CYP2C19/BMR and CYP3A4/BMR are well expressed in Escherichia coli as holo proteins. The chimeras can be purified in the absence of detergent and the purified enzymes are both active and correctly folded in the absence of detergent, as demonstrated by circular dichroism and functional studies. Additionally, in comparison with the parent P450 enzyme, these chimeras have greatly improved solubility properties. The chimeras are catalytically self-sufficient and present turnover rates similar to those reported for the native enzymes in reconstituted systems, unlike previously reported mammalian cytochrome P450 fusion proteins. Furthermore the specific activities of these chimeras are not dependent on the enzyme concentration present in the reaction buffer and they do not require the addition of accessory proteins, detergents or phospholipids to be fully active. The solubility, catalytic self-sufficiency and wild-type like activities of these chimeras would greatly simplify the studies of cytochrome P450 mediated drug metabolism in solution.

  15. Augmented oxygen-mediated transcriptional activation of cytochrome P450 (CYP)1A expression and increased susceptibilities to hyperoxic lung injury in transgenic mice carrying the human CYP1A1 or mouse 1A2 promoter in vivo.

    Science.gov (United States)

    Jiang, Weiwu; Couroucli, Xanthi I; Wang, Lihua; Barrios, Roberto; Moorthy, Bhagavatula

    2011-04-01

    Supplemental oxygen administration is frequently administered to pre-term and term infants having pulmonary insufficiency. However, hyperoxia contributes to the development of bronchopulmonary dysplasia (BPD) in premature infants. Cytochrome P450 (CYP)A enzymes have been implicated in hyperoxic lung injury. In this study, we tested the hypothesis that hyperoxia induces CYP1A1 and 1A2 enzymes by transcriptional activation of the corresponding promoters in vivo, and transgenic mice expressing the human CYP1A1 or the mouse 1A2 promoter would be more susceptible to hyperoxic lung injury than wild type (WT) mice. Adult WT (CD-1) (12week-old) mice, transgenic mice carrying a 10kb human CYP1A1 promoter and the luciferase (luc) reporter gene (CYP1A1-luc), or mice expressing the mouse CYP1A2 promoter (CYP1A2-luc) were maintained in room air or exposed to hyperoxia for 24-72h. Hyperoxia exposure of CYP1A1-luc mice for 24 and 48h resulted in 2.5- and 1.25-fold increases, respectively, in signal intensities, compared to room air controls. By 72h, the induction had declined to control levels. CYP1A2-luc mice also showed enhanced luc expression after 24-48h, albeit to a lesser extent than those expressing the CYP1A1 promoter. Also, these mice showed decreased levels of endogenous CYP1A1 and 1A2 expression after prolonged hyperoxia, and were also more susceptible to lung injury than similarly exposed WT mice, with CYP1A2-luc mice showing the greatest injury. Our results support the hypothesis that hyperoxia induces CYP1A enzymes by transcriptional activation of its corresponding promoters, and that decreased endogenous expression of these enzymes contribute to the increased susceptibilities to hyperoxic lung injury in the transgenic animals. In summary, this is the first report providing direct evidence of hyperoxia-mediated induction of CYP1A1 and CYP1A2 expression in vivo by mechanisms entailing transcriptional activation of the corresponding promoters, a phenomenon that has

  16. High-throughput screening of inhibitory effects of Bo-yang-hwan-o-tang on human cytochrome P450 isoforms in vitro using UPLC/MS/MS.

    Science.gov (United States)

    Lee, Miran; Park, Jeonghyeon; Lim, Mi-sun; Seong, Sook Jin; Lee, Joomi; Seo, Jeong Ju; Park, Yong-Ki; Lee, Hae Won; Yoon, Young-Ran

    2012-01-01

    Bo-yang-hwan-o-tang (BHT) is an oriental herbal medicine for treating brain disorders such as cerebral ischemia. The objective of this study was to develop an economically feasible and time-saving high-throughput screening method to monitor the potential inhibitory effects of BHT on human cytochrome P450 (CYP) enzymes in vitro. Two cocktail sets were used for incubation of human liver microsomes: Cocktail A: 6 probe substrates for CYP1A2, CYP2A6, CYP2C8, CYP2C19, CYP2D6, CYP3A4; Cocktail B: 3 for CYP2B6, CYP2C9, CYP2E1. The concentrations of the substrate metabolites were simultaneously analyzed using UPLC/MS/MS. The BHT extract had almost negligible inhibitory effects on the nine human CYP isoforms tested, with the half-maximal inhibitory concentration value ranged from 3624.99 to 45412.44 μg/ml. The results suggest that BHT extract has no inhibitory effects on CYP isoforms within the clinically recommended dosage range. We conclude that BHT might be free of drug-herb interactions when co-administered with other medicines. However, more in vivo human studies are needed to confirm these results. The high-throughput screening method can be a useful tool for drug discovery and for understanding drug interactions.

  17. Stable expression of human cytochrome P450 2D6*10 in HepG2 cells

    Institute of Scientific and Technical Information of China (English)

    Jian Zhuge; Ying-Nian Yu; Xiao-Dan Wu

    2004-01-01

    AIM: Over 90% of drugs are metabolized by the cytochrome P-450 (CYP) family of liver isoenzymes. The most important enzymes are CYP1A2, 3A4, 2C9/19, 2D6 and 2E1. Although CYP2D6 accounts for <2% of the total CYP liver enzyme content, it mediates metabolism in almost 25% of drugs. In order to study its enzymatic activity for drug metabolism, its cDNA was cloned and a HepG2 cell line stably expressing CYP2D6 was established.METHODS: Human CYP2D6 cDNA was amplified with reverse transcription-polymerase chain reaction (RT-PCR)from total RNA extracted from human liver tissue and cloned into pGEM-T vector, cDNA segment was identified by DNA sequencing and subcloned into a mammalian expression vector pREP9. A cell line was established by transfecting the recombinant plasmid of pREP9-CYP2D6 to hepatoma HepG2 cells. Expression of mRNA was validated by RT-PCR.Enzyme activity of catalyzing dextromethorphan O-demethylation in postmitochondrial supernant (S9) fraction of the cells was determined by high performance liquid chromatography (HPLC).RESULTS: The cloned cDNA had 4 base differences, e.g.100 C→T, 336 T→C, 408 C→G and 1 457 G→C, which resulted in P34S, and S486T amino acid substitutions, and two samesense mutations were 112 F and 136 V compared with that reported by Kimura et al(GenBank accession number: M33388). P34S and S486T amino acid substitutions were the characteristics of CYP2D6*10 allele. The relative activity of S9 fraction of HepG2-CYP2D6*10 metabolized detromethorphan O-demethylation was found to be 2.31±0.19 nmol.min-1.mg-1 S9 protein (n=3), but was undetectable in parental HepG2 cells.CONCLUSION: cDNA of human CYP2D6*10can be successfully doned. A cell line, HepG2-CYP2D6*10, expressing CYP2D6*10 mRNA and having metabolic activity, has been established.

  18. Human cytochrome p450 enzyme specificity for the bioactivation of estragole and related alkenylbenzenes

    NARCIS (Netherlands)

    Jeurissen, S.M.F.; Punt, A.; Boersma, M.G.; Bogaards, J.J.P.; Fiamegos, Y.C.; Schilter, B.; Bladeren, van P.J.; Cnubben, N.H.P.; Rietjens, I.M.C.M.

    2007-01-01

    Human cytochrome P450 enzymes involved in the bioactivation of estragole to its proximate carcinogen 1 '-hydroxyestragole were identified and compared to the enzymes of importance for 1'-hydroxylation of the related alkenylbenzenes methyleugenol and safrole. Incubations with Supersomes revealed that

  19. Human cytochrome P450 enzyme specificity for the bioactivation of estragole and related alkenylbenzenes

    NARCIS (Netherlands)

    Jeurissen, S.M.F.; Punt, A.; Boersma, M.G.; Bogaards, J.J.P.; Fiamegos, Y.C.; Schilter, B.; Bladeren, P.J. van; Cnubben, N.H.P.; Rietjens, I.M.C.M.

    2007-01-01

    Human cytochrome P450 enzymes involved in the bioactivation of estragole to its proximate carcinogen 1′-hydroxyestragole were identified and compared to the enzymes of importance for 1′-hydroxylation of the related alkenylbenzenes methyleugenol and safrole. Incubations with Supersomes revealed that

  20. METABOLISM OF MYCLOBUTANIL AND TRIADIMEFON BY HUMAN AND RAT CYTOCHROME P450 ENZYMES AND LIVER MICROSOMES.

    Science.gov (United States)

    Metabolism of two triazole-containing antifungal azoles was studied using expressed human and rat cytochrome P450s (CYP) and liver microsomes. Substrate depletion methods were used due to the complex array of metabolites produced from myclobutanil and triadimefon. Myclobutanil wa...

  1. Optical isomers of dihydropyridine calcium channel blockers display enantiospecific effects on the expression and enzyme activities of human xenobiotics-metabolizing cytochromes P450.

    Science.gov (United States)

    Štěpánková, Martina; Krasulová, Kristýna; Dořičáková, Aneta; Kurka, Ondřej; Anzenbacher, Pavel; Dvořák, Zdeněk

    2016-11-16

    Dihydropyridine calcium channel blockers (CCBs) are used as anti-hypertensives and in the treatment of angina pectoris. Structurally, CCBs have at least one chiral center in the molecule, thereby existing in two or more different enantiomers. In the current paper we examined effects of benidipine, felodipine and isradipine enantiomers on the expression and enzyme activities of human xenobiotics-metabolizing cytochromes P450. All CCBs dose-dependently activated aryl hydrocarbon receptor (AhR) and pregnane X receptor (PXR), as revealed by gene reporter assays. Activation of AhR, but not PXR, was enantiospecific. Consistently, CCBs induced CYP1A1 and CYP1A2 mRNAs, but not protein, in human hepatocytes and HepG2 cells, with following pattern: benidipine (-)>(+), isradipine (-)>(+) and felodipine (+)>(-). All CCBs induced CYP2A6, CYP2B6 and CYP3A4 mRNA and protein in human hepatocytes, and there were not differences between the enantiomers. All CCBs transformed AhR in its DNA-binding form, as revealed by electromobility shift assay. Tested CCBs inhibited enzyme activities of CYP3A4 (benidipine (+)>(-); felodipine (-)>(+); isradipine (-)-(+)) and CYP2C9 (benidipine (-)>(+); felodipine (+)>(-); isradipine (-)>(+)). The data presented here might be of toxicological and clinical importance.

  2. Expression of P450c17 messenger ribonucleic acid in postmenopausal human ovary tissues.

    Science.gov (United States)

    José, M; Puche, C; Cabero, A; Cabero, L; Meseguer, A

    1999-03-01

    To investigate the expression of the P450c17 gene in postmenopausal human ovaries compared with normal cycling ovaries. Prospective nonrandomized clinical research study. Servei de Medicina Reproductiva and Centre d'Investigacions en Bioquimica i Biologia Molecular, Hospitals Vall d'Hebron, Barcelona, Spain. Six premenopausal women and four postmenopausal women undergoing bilateral oophorectomy for nonovarian gynecologic disease. Extraction of 10 mL of peripheral venous blood for hormone measurements. Extraction of RNA from surgically removed ovaries for Northern blot, ribonuclease protection, and reverse transcriptase polymerase chain reaction Southern blot assays. Definition of the reproductive cycle state of each patient and determination of the level of P450c17 gene expression in all samples with the use of the semiquantitative reverse transcriptase polymerase chain reaction Southern blot assay. P450c17 messenger RNA levels in postmenopausal ovaries varied considerably between samples. Although the levels were similar to those detected in the early follicular phase, one of the samples had levels as high as those observed in the late follicular phase. Although the degree varied from one sample to another, all the postmenopausal ovaries studied expressed the P450c17 gene at the messenger RNA level. In a sample from a patient with endometrial adenocarcinoma, the level was as high as the levels observed in the late follicular phase.

  3. Characterization of triptolide hydroxylation by cytochrome P450 in human and rat liver microsomes.

    Science.gov (United States)

    Li, W; Liu, Y; He, Y-Q; Zhang, J-W; Gao, Y; Ge, G-B; Liu, H-X; Huo, H; Liu, H-T; Wang, L-M; Sun, J; Wang, Q; Yang, L

    2008-12-01

    Triptolide, the primary active component of a traditional Chinese medicine Tripterygium wilfordii Hook F, has a wide range of pharmacological activities. In the present study, the metabolism of triptolide by cytochrome P450s was investigated in human and rat liver microsomes. Triptolide was converted to four metabolites (M-1, M-2, M-3, and M-4) in rat liver microsomes and three (M-2, M-3, and M-4) in human liver microsomes. All the products were identified as mono-hydroxylated triptolides by liquid chromatography-mass spectrometry (LC-MS). The studies with chemical selective inhibitors, complementary DNA-expressed human cytochrome P450s, correlation analysis, and enzyme kinetics were also conducted. The results demonstrate that CYP3A4 and CYP2C19 could be involved in the metabolism of triptolide in human liver, and that CYP3A4 was the primary isoform responsible for its hydroxylation.

  4. Human extrahepatic cytochromes P450: function in xenobiotic metabolism and tissue-selective chemical toxicity in the respiratory and gastrointestinal tracts.

    Science.gov (United States)

    Ding, Xinxin; Kaminsky, Laurence S

    2003-01-01

    Cytochrome P450 (CYP) enzymes in extrahepatic tissues often play a dominant role in target tissue metabolic activation of xenobiotic compounds. They may also determine drug efficacy and influence the tissue burden of foreign chemicals or bioavailability of therapeutic agents. This review focuses on xenobiotic-metabolizing CYPs of the human respiratory and gastrointestinal tracts, including the lung, trachea, nasal respiratory and olfactory mucosa, esophagus, stomach, small intestine, and colon. Many CYPs are expressed in one or more of these organs, including CYP1A1, CYP1A2, CYP1B1, CYP2A6, CYP2A13, CYP2B6, CYP2C8, CYP2C9, CYP2C18, CYP2C19, CYP2D6, CYP2E1, CYP2F1, CYP2J2, CYP2S1, CYP3A4, CYP3A5, and CYP4B1. Of particular interest are the preferential expression of certain CYPs in the respiratory tract and the regional differences in CYP expression profile in different parts of the gastrointestinal tract. Current research activities on the characterization of CYP expression, function, and regulation in these tissues, as well as future research needs, are discussed.

  5. CYP1A2 rs762551 polymorphism contributes to cancer susceptibility: a meta-analysis from 19 case-control studies

    Directory of Open Access Journals (Sweden)

    Wang Hongge

    2012-11-01

    Full Text Available Abstract Background Genetic polymorphism (rs762551A>C in gene encoding cytochrome P450 1A2 (CYP1A2 has been shown to influence the inducibility of CYP1A2 expression and thus might be associated with risk of several types of human cancer. However, the results of previous studies on the associations of this polymorphism with risk of cancer are not all consistent. To clarify the potential contribution of CYP1A2 rs762551 to cancer risk, we performed a meta-analysis of the published case–control studies. Methods We used PubMed, Embase, OVID, ScienceDirect, and Chinese National Knowledge Infrastructure databases to identify the related publications for this meta-analysis. The pooled odds ratio (OR and 95% confidence interval (CI were calculated using random effect model to evaluate the association of rs762551 with cancer risk. A χ2-based Q-test was used to examine the heterogeneity assumption and the funnel plot and Egger’s test were used to examine the potential publication bias. The leave-one-out sensitivity analysis was conducted to determine whether our assumptions or decisions have a major effect on the results of the review. Results Our analysis of 19 eligible case–control studies showed a significant association between rs762551C variant with risk of cancer in the genetic model of CC versus AA (OR = 1.30, 95% CI = 1.02-1.64 and the dominant model (OR = 1.19, 95% CI = 1.04-1.36. In subgroup analysis based on ethnicity, the rs762551CC genotype was associated with increased cancer risk (OR = 1.29, 95% CI = 1.27-1.63 in co-dominate model and OR = 1.17, 95% CI = 1.02-1.34 in dominant model in Caucasians, but not in Asians and the mixed population. Conclusion These results suggested that CYP1A2 rs762551 polymorphism is likely to be associated with susceptibility to cancer in Caucasians.

  6. Similar substrate specificity of cynomolgus monkey cytochrome P450 2C19 to reported human P450 2C counterpart enzymes by evaluation of 89 drug clearances.

    Science.gov (United States)

    Hosaka, Shinya; Murayama, Norie; Satsukawa, Masahiro; Uehara, Shotaro; Shimizu, Makiko; Iwasaki, Kazuhide; Iwano, Shunsuke; Uno, Yasuhiro; Yamazaki, Hiroshi

    2015-12-01

    Cynomolgus monkeys are used widely in preclinical studies as non-human primate species. The amino acid sequence of cynomolgus monkey cytochrome P450 (P450 or CYP) 2C19 is reportedly highly correlated to that of human CYP2C19 (92%) and CYP2C9 (93%). In the present study, 89 commercially available compounds were screened to find potential substrates for cynomolgus monkey CYP2C19. Of 89 drugs, 34 were metabolically depleted by cynomolgus monkey CYP2C19 with relatively high rates. Among them, 30 compounds have been reported as substrates or inhibitors of, either or both, human CYP2C19 and CYP2C9. Several compounds, including loratadine, showed high selectivity to cynomolgus monkey CYP2C19, and all of these have been reported as human CYP2C19 and/or CYP2C9 substrates. In addition, cynomolgus monkey CYP2C19 formed the same loratadine metabolite as human CYP2C19, descarboethoxyloratadine. These results suggest that cynomolgus monkey CYP2C19 is generally similar to human CYP2C19 and CYP2C9 in its substrate recognition functionality.

  7. Expression of two drug-metabolizing cytochrome P450-enzymes in human salivary glands

    DEFF Research Database (Denmark)

    Kragelund, C; Hansen, C; Torpet, L A

    2008-01-01

    : Formalin-fixed paraffin-embedded specimens from parotid (10), submandibular (7) and labial (10) salivary glands were examined immunohistochemically and by in situ hybridization for expression of CYP1A2 and CYP3A4 protein and mRNA. RESULTS: CYP1A2 and CYP3A4 protein and mRNA were detected in ductal......OBJECTIVE: The oral cavity is constantly lubricated by saliva and even small amounts of xenobiotics and / or their metabolites in the saliva may affect the oral mucosa. Our aim was therefore to clarify if xenobiotic metabolizing enzymes CYP1A2 and CYP3A4 are expressed in salivary glands. METHODS...... and seromucous / serous acinar cells in all gland types although to a varying degree and intensity. Mucous acinar cells were positive to a lesser extent. CONCLUSION: The results indicate a xenobiotic metabolizing capability of salivary glands. This may have implications for development of oral mucosal disease...

  8. The basel cocktail for simultaneous phenotyping of human cytochrome P450 isoforms in plasma, saliva and dried blood spots.

    Science.gov (United States)

    Donzelli, Massimiliano; Derungs, Adrian; Serratore, Maria-Giovanna; Noppen, Christoph; Nezic, Lana; Krähenbühl, Stephan; Haschke, Manuel

    2014-03-01

    Phenotyping cocktails use a combination of cytochrome P450 (CYP)-specific probe drugs to simultaneously assess the activity of different CYP isoforms. To improve the clinical applicability of CYP phenotyping, the main objectives of this study were to develop a new cocktail based on probe drugs that are widely used in clinical practice and to test whether alternative sampling methods such as collection of dried blood spots (DBS) or saliva could be used to simplify the sampling process. In a randomized crossover study, a new combination of commercially available probe drugs (the Basel cocktail) was tested for simultaneous phenotyping of CYP1A2, CYP2B6, CYP2C9, CYP2C19, CYP2D6 and CYP3A4. Sixteen subjects received low doses of caffeine, efavirenz, losartan, omeprazole, metoprolol and midazolam in different combinations. All subjects were genotyped, and full pharmacokinetic profiles of the probe drugs and their main metabolites were determined in plasma, dried blood spots and saliva samples. The Basel cocktail was well tolerated, and bioequivalence tests showed no evidence of mutual interactions between the probe drugs. In plasma, single timepoint metabolic ratios at 2 h (for CYP2C19 and CYP3A4) or at 8 h (for the other isoforms) after dosing showed high correlations with corresponding area under the concentration-time curve (AUC) ratios (AUC0-24h parent/AUC0-24h metabolite) and are proposed as simple phenotyping metrics. Metabolic ratios in dried blood spots (for CYP1A2 and CYP2C19) or in saliva samples (for CYP1A2) were comparable to plasma ratios and offer the option of minimally invasive or non-invasive phenotyping of these isoforms. This new combination of phenotyping probe drugs can be used without mutual interactions. The proposed sampling timepoints have the potential to facilitate clinical application of phenotyping but require further validation in conditions of altered CYP activity. The use of DBS or saliva samples seems feasible for phenotyping of the

  9. Comparison between recombinant P450s and human liver microsomes in the determination of cytochrome P450 Michaelis-Menten constants.

    Science.gov (United States)

    Youdim, K; Dodia, R

    2010-04-01

    Non-linear dose-exposure (supra-proportionality) occurs when plasma drug concentrations increase in a non-linear fashion with increasing dose. To predict the likelihood of this, an understanding is required of the K(M), which reflects a drug ability to saturate a specific enzyme involved in its metabolism. This study assessed the accuracy of K(M) and V(max) determinations for compounds using a substrate-depletion approach with those determined using the product-formation approach, using both recombinant human cytochrome P450 (CYP) enzymes and human liver microsomes. For the vast majority of the compounds studied, the K(M)'s using recombinant CYPs and human liver microsomes in the two approaches predicted within two-fold. Further comparisons between the K(M) and V(max)-values were made between those measured using the product-formation approach and those estimated following simultaneous fitting of the Michaelis-Menten equation to all substrate depletion plots. In each case values were comparable. In conclusion, the current study showed the substrate-depletion approach can be used to estimate K(M) and V(max) using both human liver microsomes and recombinant P450s. Estimation of these parameters during early discovery will aid in the understanding of dosages at which non-linearity may occur, but potentially aid predictions of likely clinical drug-drug interactions.

  10. Identification of putative substrates for cynomolgus monkey cytochrome P450 2C8 by substrate depletion assays with 22 human P450 substrates and inhibitors.

    Science.gov (United States)

    Hosaka, Shinya; Murayama, Norie; Satsukawa, Masahiro; Uehara, Shotaro; Shimizu, Makiko; Iwasaki, Kazuhide; Iwano, Shunsuke; Uno, Yasuhiro; Yamazaki, Hiroshi

    2016-07-01

    Cynomolgus monkeys are widely used in drug developmental stages as non-human primate models. Previous studies used 89 compounds to investigate species differences associated with cytochrome P450 (P450 or CYP) function that reported monkey specific CYP2C76 cleared 19 chemicals, and homologous CYP2C9 and CYP2C19 metabolized 17 and 30 human CYP2C9 and/or CYP2C19 substrates/inhibitors, respectively. In the present study, 22 compounds selected from viewpoints of global drug interaction guidances and guidelines were further evaluated to seek potential substrates for monkey CYP2C8, which is highly homologous to human CYP2C8 (92%). Amodiaquine, montelukast, quercetin and rosiglitazone, known as substrates or competitive inhibitors of human CYP2C8, were metabolically depleted by recombinant monkey CYP2C8 at relatively high rates. Taken together with our reported findings of the slow eliminations of amodiaquine and montelukast by monkey CYP2C9, CYP2C19 and CYP2C76, the present results suggest that these at least four chemicals may be good marker substrates for monkey CYP2C8. Copyright © 2016 John Wiley & Sons, Ltd.

  11. Analysis of cellular responses to aflatoxin B{sub 1} in yeast expressing human cytochrome P450 1A2 using cDNA microarrays

    Energy Technology Data Exchange (ETDEWEB)

    Guo Yingying [Departmental of Environmental and Occupational Health Sciences, University of Washington, Seattle, WA (United States); Fred Hutchinson Cancer Research Center, Seattle, WA (United States); Breeden, Linda L. [Fred Hutchinson Cancer Research Center, Seattle, WA (United States); Fan, Wenhong [Fred Hutchinson Cancer Research Center, Seattle, WA (United States); Zhao Lueping [Fred Hutchinson Cancer Research Center, Seattle, WA (United States); Eaton, David L. [Departmental of Environmental and Occupational Health Sciences, University of Washington, Seattle, WA (United States); Fred Hutchinson Cancer Research Center, Seattle, WA (United States); Zarbl, Helmut [Departmental of Environmental and Occupational Health Sciences, University of Washington, Seattle, WA (United States) and Fred Hutchinson Cancer Research Center, Seattle, WA (United States)]. E-mail: hzarbl@fhcrc.org

    2006-01-29

    Aflatoxin B1 (AFB{sub 1}) is a potent human hepatotoxin and hepatocarcinogen produced by the mold Aspergillus flavus. In human, AFB{sub 1} is bioactivated by cytochrome P450 (CYP450) enzymes, primarily CYP1A2, to the genotoxic epoxide that forms N{sup 7}-guanine DNA adducts. To characterize the transcriptional responses to genotoxic insults from AFB{sub 1}, a strain of Saccharomyces cerevisiae engineered to express human CYP1A2 was exposed to doses of AFB{sub 1} that resulted in minimal lethality, but substantial genotoxicity. Flow cytometric analysis demonstrated a dose and time dependent S phase delay under the same treatment conditions, indicating a checkpoint response to DNA damage. Replicate cDNA microarray analyses of AFB{sub 1} treated cells showed that about 200 genes were significantly affected by the exposure. The genes activated by AFB{sub 1}-treatment included RAD51, DUN1 and other members of the DNA damage response signature reported in a previous study with methylmethane sulfonate and ionizing radiation [A.P. Gasch, M. Huang, S. Metzner, D. Botstein, S.J. Elledge, P.O. Brown, Genomic expression responses to DNA-damaging agents and the regulatory role of the yeast ATR homolog Mec1p, Mol. Biol. Cell 12 (2001) 2987-3003]. However, unlike previous studies using highly cytotoxic doses, environmental stress response genes [A.P. Gasch, P.T. Spellman, C.M. Kao, O. Carmel-Harel, M.B. Eisen, G. Storz, D. Botstein, P.O. Brown, Genomic expression programs in the response of yeast cells to environmental changes, Mol. Biol. Cell 11 (2000) 4241-4257] were largely unaffected by our dosing regimen. About half of the transcripts affected are also known to be cell cycle regulated. The most strongly repressed transcripts were those encoding the histone genes and a group of genes that are cell cycle regulated and peak in M phase and early G1. These include most of the known daughter-specific genes. The rapid and coordinated repression of histones and M/G1-specific

  12. Human cytochrome P450 enzyme specificity for bioactivation of safrole to the proximate carcinogen 1′-hydroxysafrole

    NARCIS (Netherlands)

    Jeurissen, S.M.F.; Bogaards, J.J.P.; Awad, H.M.; Boersma, M.G.; Brand, W.; Fiamegos, Y.C.; Beek, T.A. van; Alink, G.M.; Sudhölter, E.J.R.; Cnubben, N.H.P.; Rietjens, I.M.C.M.

    2004-01-01

    In the present study, the cytochrome P450 mediated bioactivation of safrole to its proximate carcinogenic metabolite, 1′-hydroxysafrole, has been investigated for the purpose of identifying the human P450 enzymes involved. The 1′-hydroxylation of safrole was characterized in a variety of in vitro te

  13. Sequential metabolism of sesamin by cytochrome P450 and UDP-glucuronosyltransferase in human liver.

    Science.gov (United States)

    Yasuda, Kaori; Ikushiro, Shinichi; Kamakura, Masaki; Munetsuna, Eiji; Ohta, Miho; Sakaki, Toshiyuki

    2011-09-01

    Our previous study revealed that CYP2C9 played a central role in sesamin monocatecholization. In this study, we focused on the metabolism of sesamin monocatechol that was further converted into the dicatechol form by cytochrome P450 (P450) or the glucuronide by UDP-glucuronosyltransferase (UGT). Catecholization of sesamin monocatechol enhances its antioxidant activity, whereas glucuronidation strongly reduces its antioxidant activity. In human liver microsomes, the glucuronidation activity was much higher than the catecholization activity toward sesamin monocatechol. In contrast, in rat liver microsomes, catecholization is predominant over glucuronidation. In addition, rat liver produced two isomers of the glucuronide, whereas human liver produced only one glucuronide. These results suggest a significant species-based difference in the metabolism of sesamin between humans and rats. Kinetic studies using recombinant human UGT isoforms identified UGT2B7 as the most important UGT isoform for glucuronidation of sesamin monocatechol. In addition, a good correlation was observed between the glucuronidation activity and UGT2B7-specific activity in in vitro studies using 10 individual human liver microsomes. These results strongly suggest that UGT2B7 plays an important role in glucuronidation of sesamin monocatechol. Interindividual difference among the 10 human liver microsomes is approximately 2-fold. These results, together with our previous results on the metabolism of sesamin by human P450, suggest a small interindividual difference in sesamin metabolism. We observed the methylation activity toward sesamin monocatechol by catechol O-methyl transferase (COMT) in human liver cytosol. On the basis of these results, we concluded that CYP2C9, UGT2B7, and COMT played essential roles in the metabolism of sesamin in the human liver.

  14. Diazinon, chlorpyrifos and parathion are metabolised by multiple cytochromes P450 in human liver.

    Science.gov (United States)

    Mutch, Elaine; Williams, Faith M

    2006-07-05

    This research describes both the activation and detoxification of diazinon, chlorpyrifos and parathion by recombinant P450 isozymes and by human liver microsomes that had been characterised for P450 marker activities. Wide variations in activity were found for diazinon (50 microM; 500 microM) activation to diazoxon, chlorpyrifos (100 microM) to chlorpyrifos oxon and parathion (5 microM, 20 microM and 200 microM) to paraoxon in NADPH-dependent reactions. In parallel, the dearylated metabolites pyrimidinol (IHMP), trichloro-2-pyridinol (TCP) and p-nitrophenol (PNP) were produced from diazinon, chlorpyrifos and parathion, respectively, with similarly wide variations in activity. There were significant correlations between diazoxon formation from diazinon (50 microM; 500 microM) with the three CYP3A4/5 marker reactions, while IHMP formation correlated significantly with the three CYP3A4/5 reactions, the CYP2C8 marker reaction (pdiazinon; CYPs 2D6, 3A5, 2B6 and 3A4 were best at producing chlorpyrifos-oxon and CYPs 2C19, 2D6, 3A5 and 3A4 at producing TCP from chlorpyrifos (100 microM). These data strongly suggest that CYPs 3A4/5, 2C8, 1A2, 2C19 and 2D6 are primarily involved in the metabolism of all three OPs, although the profile of participating isoforms was different for each of the pesticides suggesting that chemical structure influences which P450s mediate the reaction. The marked inter-individual variation in expression of the various P450 isozymes may result in sub-populations of individuals that produce higher systemic oxon levels with increased susceptibility to OP toxicity.

  15. CYP1A2 and CYP2D6 Gene Polymorphisms in Schizophrenic Patients with Neuroleptic Drug-Induced Side Effects.

    Science.gov (United States)

    Ivanova, S A; Filipenko, M L; Vyalova, N M; Voronina, E N; Pozhidaev, I V; Osmanova, D Z; Ivanov, M V; Fedorenko, O Yu; Semke, A V; Bokhan, N A

    2016-03-01

    Polymorphic variants of CYP1A2 and CYP2D6 genes of the cytochrome P450 system were studied in patients with schizophrenia with drug-induced motor disorders and hyperprolactinemia against the background of long-term neuroleptic therapy. We revealed an association of polymorphic variant C-163A CYP1A2*1F of CYP1A2 gene with tardive dyskinesia and association of polymorphic variant 1846G>A CY2D6*4 and genotype A/A of CYP2D6 gene (responsible for debrisoquin-4-hydroxylase synthesis) with limbotruncal tardive dyskinesia in patients with schizophrenia receiving neuroleptics for a long time.

  16. A cytochrome P450 phenotyping cocktail causing unexpected adverse reactions in female volunteers

    DEFF Research Database (Denmark)

    Pedersen, Rasmus Steen; Damkier, Per; Hougaard Christensen, Mette Marie

    2013-01-01

    A four-drug cytochrome P450 (CYP) phenotyping cocktail was developed to rapidly and safely determine CYP2D6, CYP2C19, CYP2C9 and CYP1A2 enzyme activity and phenotype.......A four-drug cytochrome P450 (CYP) phenotyping cocktail was developed to rapidly and safely determine CYP2D6, CYP2C19, CYP2C9 and CYP1A2 enzyme activity and phenotype....

  17. Mammalian Cytochrome P450-Dependent Metabolism of Polychlorinated Dibenzo-p-dioxins and Coplanar Polychlorinated Biphenyls

    OpenAIRE

    Hideyuki Inui; Toshimasa Itoh; Keiko Yamamoto; Shin-Ichi Ikushiro; Toshiyuki Sakaki

    2014-01-01

    Polychlorinated dibenzo-p-dioxins (PCDDs) and coplanar polychlorinated biphenyls (PCBs) contribute to dioxin toxicity in humans and wildlife after bioaccumulation through the food chain from the environment. The authors examined human and rat cytochrome P450 (CYP)-dependent metabolism of PCDDs and PCBs. A number of human CYP isoforms belonging to the CYP1 and CYP2 families showed remarkable activities toward low-chlorinated PCDDs. In particular, human CYP1A1, CYP1A2, and CYP1B1 showed high ac...

  18. Inhibitory effect of imperatorin and isoimperatorin on activity of cytochrome P450 enzyme in human and rat liver microsomes%欧前胡素和异欧前胡素对人和大鼠肝微粒体细胞色素P450酶活性的抑制作用

    Institute of Scientific and Technical Information of China (English)

    曹艳; 钟玉环; 原梅; 李桦; 赵春杰

    2013-01-01

    欧前胡索(IM)和异欧前胡素(ISOIM)是伞形科常用中药的主要有效成分,在临床上广泛应用.该文研究了IM和ISOIM对人和大鼠肝微粒体细胞色素P450酶(CYP)活性的抑制作用,并评价它们的相互作用潜能.在体外将系列浓度的IM和ISOIM与人和大鼠肝微粒体孵育30 min,以非那西丁、安非他酮、甲苯磺丁脲、S-美芬妥英、右美沙芬和咪达唑仑为CYP探针底物,应用LC-MS/MS定量检测各探针底物的代谢产物生成量,计算得到的IC50,评价两药对人肝CYP1 A2,2B6,2C9,2C19,206,3A4酶,以及大鼠肝CYP1 A2,2B6,2D2,3A1/2酶的抑制活性,并对抑制强度进行分级.在人肝微粒体中,IM和ISOIM对6个CYP同工酶均有不同程度的抑制作用.它们是1A2和2B6的强抑制剂,抑制1A2的IC50分别为0.05,0.20 μmol·L-1;抑制2B6的IC50分别为0.18,1.07 μmol·L-1.两药还是2C19的中等抑制剂,以及2C9,2D6,3A4的弱抑制剂.在大鼠肝微粒体中,IM和ISOIM是1A2的中等抑制剂,IC50分别为1.95,2.98 μmol·L-1.它们分别是2B6的中等和弱抑制剂,IC50为6.22,21.71 μmol·L-1.两药还是2D2,3A1/2的弱抑制剂.结果表明IM,ISOIM对人肝CYP酶有广泛的抑制作用,它们是CYP1A2和2B6酶的强抑制剂,临床用药时应注意因CYP酶抑制引起的相互作用.%Imperatorin (IM) and isoimperatorin (ISOIM) are major active components of common herbal medicines from Umbelliferae plants,and widely used in clinic.This article studies the inhibitory effect of IM and ISOIM on the activity of cytochrome P450 (CYP) enzyme,and assesses their potential drug-drug interaction.IM and ISOIM were incubated separately with human or rat liver microsomes for 30 min,with phenacetin,bupropion,tolbutamide,S-mephenytoin,dextromethorphan and midazolam as probe substrates.Metabolites of the CYP probe substrates were determined by LC-MS/MS,and IC50values were calculated to assess the inhibitory effect of the two drugs on human CYP1A2,2B6,2C9,2C19,2D6 and 3A4

  19. Pi-pi Stacking Mediated Cooperative Mechanism for Human Cytochrome P450 3A4

    Directory of Open Access Journals (Sweden)

    Botao Fa

    2015-04-01

    Full Text Available Human Cytochrome P450 3A4 (CYP3A4 is an important member of the cytochrome P450 superfamily with responsibility for metabolizing ~50% of clinical drugs. Experimental evidence showed that CYP3A4 can adopt multiple substrates in its active site to form a cooperative binding model, accelerating substrate metabolism efficiency. In the current study, we constructed both normal and cooperative binding models of human CYP3A4 with antifungal drug ketoconazoles (KLN. Molecular dynamics simulation and free energy calculation were then carried out to study the cooperative binding mechanism. Our simulation showed that the second KLN in the cooperative binding model had a positive impact on the first one binding in the active site by two significant pi-pi stacking interactions. The first one was formed by Phe215, functioning to position the first KLN in a favorable orientation in the active site for further metabolism reactions. The second one was contributed by Phe304. This pi-pi stacking was enhanced in the cooperative binding model by the parallel conformation between the aromatic rings in Phe304 and the dioxolan moiety of the first KLN. These findings can provide an atomic insight into the cooperative binding in CYP3A4, revealing a novel pi-pi stacking mechanism for drug-drug interactions.

  20. Inhibition of human P450 enzymes by natural extracts used in traditional medicine.

    Science.gov (United States)

    Rodeiro, Idania; Donato, María T; Jimenez, Nuria; Garrido, Gabino; Molina-Torres, Jorge; Menendez, Roberto; Castell, José V; Gómez-Lechón, María J

    2009-02-01

    Different medicinal plants are widely used in Cuba and Mexico to treat several disorders. This paper reports in vitro inhibitory effects on the P450 system of herbal products commonly used by people in Cuba and Mexico in traditional medicine for decades. Experiments were conducted in human liver microsomes. The catalytic activities of CYP1A1/2, 2D6, and 3A4 were measured using specific probe substrates. The Heliopsis longipes extract exhibited a concentration-dependent inhibition of the three enzymes, and similar effects were produced by affinin (an alkamide isolated from the H. longipes extract) and two catalytically reduced alkamides. Mangifera indica L. and Thalassia testudinum extracts, two natural polyphenol-rich extracts, diminished CYP1A1/2 and 3A4 activities, but not the CYP2D6 activity. These results suggest that these herbs inhibit the major human P450 enzymes involved in drug metabolism and could induce potential herbal-drug interactions.

  1. Inhibitory Effects of Aschantin on Cytochrome P450 and Uridine 5′-diphospho-glucuronosyltransferase Enzyme Activities in Human Liver Microsomes

    Directory of Open Access Journals (Sweden)

    Soon-Sang Kwon

    2016-04-01

    Full Text Available Aschantin is a bioactive neolignan found in Magnolia flos with antiplasmodial, Ca2+-antagonistic, platelet activating factor-antagonistic, and chemopreventive activities. We investigated its inhibitory effects on the activities of eight major human cytochrome P450 (CYP and uridine 5′-diphospho-glucuronosyltransferase (UGT enzymes of human liver microsomes to determine if mechanistic aschantin–enzyme interactions were evident. Aschantin potently inhibited CYP2C8-mediated amodiaquine N-de-ethylation, CYP2C9-mediated diclofenac 4′-hydroxylation, CYP2C19-mediated [S]-mephenytoin 4′-hydroxylation, and CYP3A4-mediated midazolam 1′-hydroxylation, with Ki values of 10.2, 3.7, 5.8, and 12.6 µM, respectively. Aschantin at 100 µM negligibly inhibited CYP1A2-mediated phenacetin O-de-ethylation, CYP2A6-mediated coumarin 7-hydroxylation, CYP2B6-mediated bupropion hydroxylation, and CYP2D6-mediated bufuralol 1′-hydroxylation. At 200 µM, it weakly inhibited UGT1A1-catalyzed SN-38 glucuronidation, UGT1A6-catalyzed N-acetylserotonin glucuronidation, and UGT1A9-catalyzed mycophenolic acid glucuronidation, with IC50 values of 131.7, 144.1, and 71.0 µM, respectively, but did not show inhibition against UGT1A3, UGT1A4, or UGT2B7 up to 200 µM. These in vitro results indicate that aschantin should be examined in terms of potential interactions with pharmacokinetic drugs in vivo. It exhibited potent mechanism-based inhibition of CYP2C8, CYP2C9, CYP2C19, and CYP3A4.

  2. Simultaneous pharmacokinetics evaluation of human cytochrome P450 probes, caffeine, warfarin, omeprazole, metoprolol and midazolam, in common marmosets (Callithrix jacchus).

    Science.gov (United States)

    Uehara, Shotaro; Inoue, Takashi; Utoh, Masahiro; Toda, Akiko; Shimizu, Makiko; Uno, Yasuhiro; Sasaki, Erika; Yamazaki, Hiroshi

    2016-01-01

    1. Pharmacokinetics of human cytochrome P450 probes (caffeine, racemic warfarin, omeprazole, metoprolol and midazolam) composite, after single intravenous and oral administrations at doses of 0.20 and 1.0 mg kg(-1), respectively, to four male common marmosets were investigated. 2. The plasma concentrations of caffeine and warfarin decreased slowly in a monophasic manner but those of omeprazole, metoprolol and midazolam decreased extensively after intravenous and oral administrations, in a manner that approximated those as reported for pharmacokinetics in humans. 3. Bioavailabilities were ∼100% for caffeine and warfarin, but midazolam was 4% in marmosets, presumably because of contribution of marmoset P450 3A4 expressed in small intestine and liver, with a high catalytic efficiency for midazolam 1'-hydroxylation as evident in the recombinant system. 4. These results suggest that common marmosets, despite their rapid clearance of some human P450 probe substrates, could be an experimental model for humans and that marmoset P450s have functional characteristics that differ from those of human and/or cynomolgus monkey P450s in some aspects, indicating their importance in modeling in P450-dependent drug metabolism studies in marmosets and of further studies.

  3. The influence of a CYP1A2 polymorphism on the ergogenic effects of caffeine

    Directory of Open Access Journals (Sweden)

    Womack Christopher J

    2012-03-01

    Full Text Available Abstract Background Although caffeine supplementation improves performance, the ergogenic effect is variable. The cause(s of this variability are unknown. A (C/A single nucleotide polymorphism at intron 1 of the cytochrome P450 (CYP1A2 gene influences caffeine metabolism and clinical outcomes from caffeine ingestion. The purpose of this study was to determine if this polymorphism influences the ergogenic effect of caffeine supplementation. Methods Thirty-five trained male cyclists (age = 25.0 ± 7.3 yrs, height = 178.2 ± 8.8 cm, weight = 74.3 ± 8.8 kg, VO2max = 59.35 ± 9.72 ml·kg-1·min-1 participated in two computer-simulated 40-kilometer time trials on a cycle ergometer. Each test was performed one hour following ingestion of 6 mg·kg-1 of anhydrous caffeine or a placebo administered in double-blind fashion. DNA was obtained from whole blood samples and genotyped using restriction fragment length polymorphism-polymerase chain reaction. Participants were classified as AA homozygotes (N = 16 or C allele carriers (N = 19. The effects of treatment (caffeine, placebo and the treatment × genotype interaction were assessed using Repeated Measures Analysis of Variance. Results Caffeine supplementation reduced 40 kilometer time by a greater (p Conclusions Results suggest that individuals homozygous for the A allele of this polymorphism may have a larger ergogenic effect following caffeine ingestion.

  4. Low Potential of Basimglurant to Be Involved in Drug-Drug Interactions: Influence of Non-Michaelis-Menten P450 Kinetics on Fraction Metabolized.

    Science.gov (United States)

    Fowler, Stephen; Guerini, Elena; Qiu, NaHong; Cleary, Yumi; Parrott, Neil; Greig, Gerard; Mallalieu, Navita L

    2017-01-01

    Basimglurant, a novel mGlu5-negative allosteric modulator under development for the treatment of major depressive disorder, is cleared via cytochrome P450 (P450)-mediated oxidative metabolism. Initial enzyme phenotyping studies indicated that CYP3A4/5 dominates basimglurant metabolism and highlights a risk for drug-drug interactions when it is comedicated with strong CYP3A4/5 inhibitors or inactivators; however, a clinical drug-drug interaction (DDI) study using the potent and selective CYP3A4/5 inhibitor ketoconazole resulted in an area under the curve (AUC) AUCi/AUC ratio of only 1.24. A further study using the CYP3A4 inducer carbamazepine resulted in an AUCi/AUC ratio of 0.69. More detailed in vitro enzyme phenotyping and kinetics studies showed that, at the low concentrations attained clinically, basimglurant metabolic clearance is catalyzed mainly by CYP1A2. The relative contributions of the enzymes were estimated as 70:30 CYP1A2:CYP3A4/5. Using this information, a clinical study using the CYP1A2 inhibitor fluvoxamine was performed, resulting in an AUCi/AUC ratio of 1.60, confirming the role of CYP1A2 and indicating a balanced DDI risk profile. Basimglurant metabolism kinetics show enzyme dependency: CYP1A2-mediated metabolism follows Michaelis-Menten kinetics, whereas CYP3A4 and CYP3A5 follow sigmoidal kinetics [with similar constant (KM) and S50 values]. The interplay of the different enzyme kinetics leads to changing fractional enzyme contributions to metabolism with substrate concentration, even though none of the metabolic enzymes is saturated. This example demonstrates the relevance of non-Michaelis-Menten P450 enzyme kinetics and highlights the need for a thorough understanding of metabolism enzymology to make accurate predictions for human metabolism in vivo. Copyright © 2016 by The American Society for Pharmacology and Experimental Therapeutics.

  5. Water pipe (Shisha, Hookah, Arghile) Smoking and Secondhand Tobacco Smoke Effects on CYP1A2 and CYP2A6 Phenotypes as Measured by Caffeine Urine Test.

    Science.gov (United States)

    Yılmaz, Şenay Görücü; Llerena, Adrián; De Andrés, Fernando; Karakaş, Ümit; Gündoğar, Hasan; Erciyas, Kamile; Kimyon, Sabit; Mete, Alper; Güngör, Kıvanç; Özdemir, Vural

    2017-03-01

    Public policies to stop or reduce cigarette smoking and exposure to secondhand smoke and associated diseases have yielded successful results over the past decade. Yet, the growing worldwide popularity of another form of tobacco consumption, water pipe smoking, has received relatively less attention. To the best of our knowledge, no study to date has evaluated the effects of water pipe smoking on cytochrome P450 (CYP450) activities and drug interaction potential in humans, whereas only limited information is available on the impact of secondhand smoke on drug metabolism. In a sample of 99 healthy volunteers (28 water pipe smokers, 30 secondhand tobacco smoke exposed persons, and 41 controls), we systematically compared CYP1A2 and CYP2A6 enzyme activities in vivo using caffeine urine test. The median self-reported duration of water pipe smoking was 7.5 h/week and 3 years of exposure in total. The secondhand smoke group had a median of 14 h of self-reported weekly exposure to tobacco smoke indoor where a minimum of five cigarettes were smoked/hour for a total of 3.5 years (median). Analysis of variance did not find a significant difference in CYP1A2 and CYP2A6 activities among the three study groups (p > 0.05). Nor was there a significant association between the extent of water pipe or secondhand smoke exposure and the CYP1A2 and CYP2A6 activities (p > 0.05). Further analysis in a subsample with smoke exposure more than the median values also did not reveal a significant difference from the controls. Although we do not rule out an appreciable possible impact of water pipe smoke and secondhand smoke on in vivo activities of these two drug metabolism pathways, variability in smoke constituents from different tobacco consumption methods (e.g., water pipe) might affect drug metabolism in ways that might differ from that of cigarette smoke. Further studies in larger prospective samples are recommended to evaluate water pipe and secondhand tobacco smoke effects

  6. Mechanistic Scrutiny Identifies a Kinetic Role for Cytochrome b5 Regulation of Human Cytochrome P450c17 (CYP17A1, P450 17A1)

    Science.gov (United States)

    Simonov, Alexandr N.; Holien, Jessica K.; Yeung, Joyee Chun In; Nguyen, Ann D.; Corbin, C. Jo; Zheng, Jie; Kuznetsov, Vladimir L.; Auchus, Richard J.; Conley, Alan J.; Bond, Alan M.; Parker, Michael W.; Rodgers, Raymond J.; Martin, Lisandra L.

    2015-01-01

    Cytochrome P450c17 (P450 17A1, CYP17A1) is a critical enzyme in the synthesis of androgens and is now a target enzyme for the treatment of prostate cancer. Cytochrome P450c17 can exhibit either one or two physiological enzymatic activities differentially regulated by cytochrome b5. How this is achieved remains unknown. Here, comprehensive in silico, in vivo and in vitro analyses were undertaken. Fluorescence Resonance Energy Transfer analysis showed close interactions within living cells between cytochrome P450c17 and cytochrome b5. In silico modeling identified the sites of interaction and confirmed that E48 and E49 residues in cytochrome b5 are essential for activity. Quartz crystal microbalance studies identified specific protein-protein interactions in a lipid membrane. Voltammetric analysis revealed that the wild type cytochrome b5, but not a mutated, E48G/E49G cyt b5, altered the kinetics of electron transfer between the electrode and the P450c17. We conclude that cytochrome b5 can influence the electronic conductivity of cytochrome P450c17 via allosteric, protein-protein interactions. PMID:26587646

  7. Mechanistic Scrutiny Identifies a Kinetic Role for Cytochrome b5 Regulation of Human Cytochrome P450c17 (CYP17A1, P450 17A1.

    Directory of Open Access Journals (Sweden)

    Alexandr N Simonov

    Full Text Available Cytochrome P450c17 (P450 17A1, CYP17A1 is a critical enzyme in the synthesis of androgens and is now a target enzyme for the treatment of prostate cancer. Cytochrome P450c17 can exhibit either one or two physiological enzymatic activities differentially regulated by cytochrome b5. How this is achieved remains unknown. Here, comprehensive in silico, in vivo and in vitro analyses were undertaken. Fluorescence Resonance Energy Transfer analysis showed close interactions within living cells between cytochrome P450c17 and cytochrome b5. In silico modeling identified the sites of interaction and confirmed that E48 and E49 residues in cytochrome b5 are essential for activity. Quartz crystal microbalance studies identified specific protein-protein interactions in a lipid membrane. Voltammetric analysis revealed that the wild type cytochrome b5, but not a mutated, E48G/E49G cyt b5, altered the kinetics of electron transfer between the electrode and the P450c17. We conclude that cytochrome b5 can influence the electronic conductivity of cytochrome P450c17 via allosteric, protein-protein interactions.

  8. Dynamics of water molecules in the active-site cavity of human cytochromes P450

    DEFF Research Database (Denmark)

    Rydberg, Patrik; Rod, Thomas Holm; Olsen, Lars;

    2007-01-01

    have quite big cavities, with 41 water molecules on average in 2C8 and 54-58 in 2C9 and 3A4, giving a water volume of 1500-2100 A3. The two crystal structures of 2C9 differ quite appreciably, whereas those of 3A4 are quite similar. The active-site cavity is connected to the surroundings by three to six......We have studied the dynamics of water molecules in six crystal structures of four human cytochromes P450, 2A6, 2C8, 2C9, and 3A4, with molecular dynamics simulations. In the crystal structures, only a few water molecules are seen and the reported sizes of the active-site cavity vary a lot...

  9. Acute hypoxia and cytochrome P450-mediated hepatic drug metabolism in humans

    DEFF Research Database (Denmark)

    Jürgens, Gesche; Christensen, Hanne Rolighed; Brøsen, Kim;

    2002-01-01

    Our objective was to investigate the effect of acute hypoxia on the activity of hepatic cytochrome P450 (CYP) enzymes.......Our objective was to investigate the effect of acute hypoxia on the activity of hepatic cytochrome P450 (CYP) enzymes....

  10. Structural basis for human NADPH-cytochrome P450 oxidoreductase deficiency

    Energy Technology Data Exchange (ETDEWEB)

    Xia, Chuanwu; Panda, Satya P.; Marohnic, Christopher C.; Martásek, Pavel; Masters, Bettie Sue; Kim, Jung-Ja P. (MCW); (Charles U); (UTSMC)

    2012-03-15

    NADPH-cytochrome P450 oxidoreductase (CYPOR) is essential for electron donation to microsomal cytochrome P450-mediated monooxygenation in such diverse physiological processes as drug metabolism (approximately 85-90% of therapeutic drugs), steroid biosynthesis, and bioactive metabolite production (vitamin D and retinoic acid metabolites). Expressed by a single gene, CYPOR's role with these multiple redox partners renders it a model for understanding protein-protein interactions at the structural level. Polymorphisms in human CYPOR have been shown to lead to defects in bone development and steroidogenesis, resulting in sexual dimorphisms, the severity of which differs significantly depending on the degree of CYPOR impairment. The atomic structure of human CYPOR is presented, with structures of two naturally occurring missense mutations, V492E and R457H. The overall structures of these CYPOR variants are similar to wild type. However, in both variants, local disruption of H bonding and salt bridging, involving the FAD pyrophosphate moiety, leads to weaker FAD binding, unstable protein, and loss of catalytic activity, which can be rescued by cofactor addition. The modes of polypeptide unfolding in these two variants differ significantly, as revealed by limited trypsin digestion: V492E is less stable but unfolds locally and gradually, whereas R457H is more stable but unfolds globally. FAD addition to either variant prevents trypsin digestion, supporting the role of the cofactor in conferring stability to CYPOR structure. Thus, CYPOR dysfunction in patients harboring these particular mutations may possibly be prevented by riboflavin therapy in utero, if predicted prenatally, or rescued postnatally in less severe cases.

  11. Highly miniaturized formats for in vitro drug metabolism assays using vivid fluorescent substrates and recombinant human cytochrome P450 enzymes.

    Science.gov (United States)

    Trubetskoy, Olga V; Gibson, Jasmin R; Marks, Bryan D

    2005-02-01

    Highly miniaturized P450 screening assays designed to enable facile analysis of P450 drug interactions in a 1536-well plate format with the principal human cytochrome P450 enzymes (CYP3A4, 2D6, 2C9, 2C19, and 1A2) and Vivid fluorogenic substrates were developed. The detailed characterization of the assays included stability, homogeneity, and reproducibility of the recombinant P450 enzymes and the kinetic parameters of their reactions with Vivid fluorogenic substrates, with a focus on the specific characteristics of each component that enable screening in a low-volume 1536-well plate assay format. The screening assays were applied for the assessment of individual cytochrome P450 inhibition profiles with a panel of selected assay modifiers, including isozyme-specific substrates and inhibitors. IC(50) values obtained for the modifiers in 96- and 1536-well plate formats were similar and comparable with values obtained in assays with conventional substrates. An overall examination of the 1536-well assay statistics, such as signal-to-background ratio and Z' factor, demonstrated that these assays are a robust, successful, and reliable tool to screen for cytochrome P450 metabolism and inhibition in an ultra-high-throughput screening format.

  12. Expression of the cytochrome P450 epoxygenase CYP2J2 in human monocytic leukocytes.

    Science.gov (United States)

    Nakayama, Kaeko; Nitto, Takeaki; Inoue, Teruo; Node, Koichi

    2008-08-29

    CYP2J2 is one of the cytochrome P450 epoxygenases involved in the metabolism of arachidonic acid. CYP2J2 has been identified in several tissues, especially cardiovascular tissues. CYP2J2 has cardiovascular effects, as epoxyeicosatrienoic acid, one of its metabolites, has anti-inflammatory and vasodilative activities. We investigated the expression of CYP2J2 in human leukocytes using reverse transcription-polymerase chain reaction, immunoblotting and immunostaining. Human monocytic cells, but not human neutrophils, exhibited constitutive expression of CYP2J2. Furthermore, the expression of CYP2J2 mRNA increased when the human monocytic cell line THP-1 cells and human monocytes were stimulated with phorbol 12-myristate 13-acetate and macrophage-colony stimulating factor in combination with granulocyte/macrophage-colony stimulating factor, respectively. These results suggest that expression of CYP2J2 was up-regulated when human monocytes differentiated into macrophages and that human monocytic cells and macrophages have a pathway to metabolize arachidonic acid using CYP epoxygenases.

  13. Evaluation of Luminescent P450 Analysis for Directed Evolution of Human CYP4A11.

    Science.gov (United States)

    Choi, Seunghye; Han, Songhee; Lee, Hwayoun; Chun, Young-Jin; Kim, Donghak

    2013-11-01

    Cytochrome P450 4A11 (CYP4A11) is a fatty acid hydroxylase enzyme expressed in human liver. It catalyzes not only the hydroxylation of saturated and unsaturated fatty acids, but the conversion of arachidonic acid to 20-hydroxyeicosatetraenoic acid (20-HETE), a regulator of blood pressure. In this study, we performed a directed evolution analysis of CYP4A11 using the luminogenic assay system. A random mutant library of CYP4A11, in which mutations were made throughout the entire coding region, was screened with luciferase activity to detect the demethylation of luciferin-4A (2-[6-methoxyquinolin-2-yl]-4,5-dihydrothiazole-4-carboxylic acid) of CYP4A11 mutants in Escherichia coli. Consecutive rounds of random mutagenesis and screening yielded three improved CYP4A11 mutants, CP2600 (A24T/T263A), CP2601 (T263A), and CP2616 (A24T/T263A/V430E) with ~3-fold increase in whole cells and >10-fold increase in purified proteins on the luminescence assay. However, the steady state kinetic analysis for lauric acid hydroxylation showed the significant reductions in enzymatic activities in all three mutants. A mutant, CP2600, showed a 51% decrease in catalytic efficiency (k cat/K m) for lauric acid hydroxylation mainly due to an increase in K m. CP2601 and CP2616 showed much greater reductions (>75%) in the catalytic efficiency due to both a decrease in k cat and an increase in K m. These decreased catalytic activities of CP2601 and CP2616 can be partially attributed to the changes in substrate affinities. These results suggest that the enzymatic activities of CYP4A11 mutants selected from directed evolution using a luminogenic P450 substrate may not demonstrate a direct correlation with the hydroxylation activities of lauric acid.

  14. Mass spectrometry-based proteomic analysis of human liver cytochrome(s) P450

    Energy Technology Data Exchange (ETDEWEB)

    Shrivas, Kamlesh; Mindaye, Samuel T.; Getie-Kebtie, Melkamu; Alterman, Michail A., E-mail: Michail.Alterman@fda.hhs.gov

    2013-02-15

    The major objective of personalized medicine is to select optimized drug therapies and to a large degree such mission is determined by the expression profiles of cytochrome(s) P450 (CYP). Accordingly, a proteomic case study in personalized medicine is provided by the superfamily of cytochromes P450. Our knowledge about CYP isozyme expression on a protein level is very limited and based exclusively on DNA/mRNA derived data. Such information is not sufficient because transcription and translation events do not lead to correlated levels of expressed proteins. Here we report expression profiles of CYPs in human liver obtained by mass spectrometry (MS)-based proteomic approach. We analyzed 32 samples of human liver microsomes (HLM) of different sexes, ages and ethnicity along with samples of recombinant human CYPs. We have experimentally confirmed that each CYP isozyme can be effectively differentiated by their unique isozyme-specific tryptic peptide(s). Trypsin digestion patterns for almost 30 human CYP isozymes were established. Those findings should assist in selecting tryptic peptides suitable for MS-based quantitation. The data obtained demonstrate remarkable differences in CYP expression profiles. CYP2E1, CYP2C8 and CYP4A11 were the only isozymes found in all HLM samples. Female and pediatric HLM samples revealed much more diverse spectrum of expressed CYPs isozymes compared to male HLM. We have confirmed expression of a number of “rare” CYP (CYP2J2, CYP4B1, CYP4V2, CYP4F3, CYP4F11, CYP8B1, CYP19A1, CYP24A1 and CYP27A1) and obtained first direct experimental data showing expression of such CYPs as CYP2F1, CYP2S1, CYP2W1, CYP4A22, CYP4X1, and CYP26A1 on a protein level. - Highlights: ► First detailed proteomic analysis of CYP isozymes expression in human liver ► Trypsin digestion patterns for almost 30 human CYP isozymes established ► The data obtained demonstrate remarkable differences in CYP expression profiles. ► Female HLM samples revealed more

  15. Bimodal action of miroestrol and deoxymiroestrol, phytoestrogens from Pueraria candollei var. mirifica, on hepatic CYP2B9 and CYP1A2 expressions and antilipid peroxidation in mice.

    Science.gov (United States)

    Udomsuk, Latiporn; Juengwatanatrakul, Thaweesak; Putalun, Waraporn; Jarukamjorn, Kanokwan

    2012-01-01

    Miroestrol and deoxymiroestrol are phytoestrogens isolated from Pueraria candollei var. mirifica. The influence of miroestrol and dexoymirosestrol on hepatic cytochrome P450 (P450) enzymes and antioxidative activity in brain was examined in C57BL/6 mice compared with that of a synthetic female sex hormone estradiol. We hypothesized that miroestrol and deoxymiroestrol would induce CYP2B9 expression, whereas CYP1A2 expression would be suppressed compared with estradiol. Miroestrol and deoxymiroestrol treatment significantly increased uterus weight and volume. In addition, both of these phytoestrogens induced the expression of CYP2B9 and suppressed the expression of CYP1A2, as expected. Hepatic P450 activities correspondingly showed that both compounds increased benzyloxyresorufin O-dealkylase activity, whereas methoxyresorufin O-dealkylase activity was reduced. These observations suggested that miroestrol and deoxymiroestrol might affect hepatic P450 enzymes, including the CYP2B9 and CYP1A2 P450 isoforms. Assessment of lipid peroxidation demonstrated that miroestrol and deoxymiroestrol markedly decreased levels of malondialdehyde formation in the mouse brain. This is the first report suggesting miroestrol and deoxymiroestrol as potential alternative medicines to estradiol because of their distinctive ability to regulate mouse hepatic P450 expression and their beneficial antioxidative activities.

  16. Cytochrome P450 isoenzymes in rat and human liver microsomes associate with the metabolism of total coumarins in Fructus Cnidii.

    Science.gov (United States)

    Hu, Xiao; Huang, Wei; Yang, Yuan

    2015-12-01

    Fructus Cnidii (Cnidium) is isolated from the dry and ripe fruit of Cnidium monnier (L.) Cuss (umbelifera), an annual herb. It is demonstrated that the active constituents of Fructus Cnidii are coumarins, known as Total Coumarins of Cnidium Monnier (TCCM). Osthole (Ost) and imperatorin (Imp) are the most active constituents of TCCM which are usually regarded as the quality indicators of medicinal Fructus Cnidii. The aim is to study the metabolism of Fructus Cnidii effective monomer osthole and imperatorin in vitro by liver microsomes. CYP3A4 inhibitor ketoconazole, CYP2D6 inhibitor qunidine, CYP2C8 inhibitor trimethoprim, CYP2C9 inhibitor sulfaphenazole, and CYP1A2 inhibitor α-naphthoflavone were used to investigate the metabolism from incubation time, substrate concentration and liver microsomal concentration, respectively. The concentration of liver microsomes was 0.2 mg/ml. Ost (0.8/3.2/12.8 uM) was incubated at 37 °C for 20 min while Imp (1.6/6.4/19.2 uM) was incubated for 30 min. Qunidine, trimethoprim and α-naphthoflavone could significantly inhibit the disappearance of Imp; meanwhile ketoconazole, sulfaphenazole and qunidine could inhibit the disappearance of Ost. CYP1A, CYP2C are involved in the metabolism of Imp and CYP3A mediates the metabolism of Ost in rat liver microsomes. In human liver microsomes, CYP1A2, CYP2C8, CYP2D6 are involved in the metabolism of Imp; CYP3A4 is involved in the metabolism of Ost at all the tested concentrations of Ost, while CYP2C9, CYP2D6 mediate the metabolism at high concentration of Ost.

  17. The Effect of Vinpocetine on Human Cytochrome P450 Isoenzymes by Using a Cocktail Method

    Directory of Open Access Journals (Sweden)

    Lingti Kong

    2016-01-01

    Full Text Available Vinpocetine is a derivative of the alkaloid vincamine, which had been prescribed for chronic cerebral vascular ischemia and acute ischemic stroke or used as a dietary supplement for its several different mechanisms of biological activities. However, information on the cytochrome P450 (CYP enzyme-mediated drug metabolism has not been previously studied. The present study was performed to investigate the effects of vinpocetine on CYPs activity, and cocktail method was used, respectively. To evaluate the effects of vinpocetine on the activity of human CYP3A4, CYP2C9, CYP2C19, CYP2D6, and CYP2E1, human liver microsomes were utilized to incubate with the mixed CYPs probe substrates and the target components. The results indicate that vinpocetine exhibited weak inhibitory effect on the CYP2C9, where the IC50 value is 68.96 μM, whereas the IC50 values for CYP3A4, CYP2C19, CYP2D6, and CYP2E1 were all over range of 100 μM, which showed that vinpocetine had no apparent inhibitory effects on these CYPs. In conclusion, the results indicated that drugs metabolized by CYP2C9 coadministrated with vinpocetine may require attention or dose adjustment.

  18. In vitro Metabolism of Strychnine by Human Cytochrome P450 and Its Interaction with Glycyrrhetic Acid

    Institute of Scientific and Technical Information of China (English)

    LIU Li; XIAO Juan; PENG Zhi-hong; WU Wen-hua; DU Peng; CHEN Yong

    2012-01-01

    Objective To investigate the metabolism of strychnine (STN) and the metabolic interaction between STN and glycyrthetic acid (GA) in vitro.Methods Human liver microsomes (HLM) and human recombinant cytochrome P450 (CYP) isoforms were employed to study the metabolism of STN and the metabolic interaction of STN with GA in vitro.Results In HLM,the Km,Vmax,and clearance of STN were 88.50 μmol/L,0.88 nmol/(mg·min),and 9.93 mL/(mg·min),respectively.STN was metabolized mainly by CYP3A4.However,STN noncompetitively inhibited CYP3A4-catalyzed testosterone 6β-hydroxylation with IC50 value of 5.9 μtmol/L and Ki value of 5.5μmol/L.Moreover,GA competitively inhibited STN metabolism with IC5o value of 10.6 μmol/L and Ki value of 17.7 μmol/L.Conclusion Although STN is mainly metabolized by CYP3A4 in vitro,STN has noncompetitive inhibition on CYP3A4-catalyzed testosterone 6β-hydroxylation.Moreover,GA could competitively inhibit STN metabolism.The present work is helpful to elucidate the metabolic interaction between STN and GA.

  19. Effect of butylated hydroxytoluene, curcumin, propyl gallate and thiabendazole on cytochrome P450 forms in cultured human hepatocytes

    NARCIS (Netherlands)

    Price, R.J.; Scott, M.P.; Giddings, A.M.; Walters, D.G.; Stierum, R.H.; Meredith, C.; Lake, B.G.

    2008-01-01

    1. The objective of this study was to investigate the effects of four food chemicals, namely butylated hydroxytoluene (BHT), curcumin (CC), propyl gallate (PG) and thiabendazole (TB), on cytochrome P450 (CYP) forms in cultured human hepatocytes. 2. Treatment of human hepatocytes for 72 h with 2-200

  20. Effect of butylated hydroxytoluene, curcumin, propyl gallate and thiabendazole on cytochrome P450 forms in cultured human hepatocytes

    NARCIS (Netherlands)

    Price, R.J.; Scott, M.P.; Giddings, A.M.; Walters, D.G.; Stierum, R.H.; Meredith, C.; Lake, B.G.

    2008-01-01

    1. The objective of this study was to investigate the effects of four food chemicals, namely butylated hydroxytoluene (BHT), curcumin (CC), propyl gallate (PG) and thiabendazole (TB), on cytochrome P450 (CYP) forms in cultured human hepatocytes. 2. Treatment of human hepatocytes for 72 h with 2-200

  1. Metabolism of Oral Turinabol by Human Steroid Hormone-Synthesizing Cytochrome P450 Enzymes.

    Science.gov (United States)

    Schiffer, Lina; Brixius-Anderko, Simone; Hannemann, Frank; Zapp, Josef; Neunzig, Jens; Thevis, Mario; Bernhardt, Rita

    2016-02-01

    The human mitochondrial cytochrome P450 enzymes CYP11A1, CYP11B1, and CYP11B2 are involved in the biosynthesis of steroid hormones. CYP11A1 catalyzes the side-chain cleavage of cholesterol, and CYP11B1 and CYP11B2 catalyze the final steps in the biosynthesis of gluco- and mineralocorticoids, respectively. This study reveals their additional capability to metabolize the xenobiotic steroid oral turinabol (OT; 4-chlor-17β-hydroxy-17α-methylandrosta-1,4-dien-3-on), which is a common doping agent. By contrast, microsomal steroid hydroxylases did not convert OT. Spectroscopic binding assays revealed dissociation constants of 17.7 µM and 5.4 µM for CYP11B1 and CYP11B2, respectively, whereas no observable binding spectra emerged for CYP11A1. Catalytic efficiencies of OT conversion were determined to be 46 min(-1) mM(-1) for CYP11A1, 741 min(-1) mM(-1) for CYP11B1, and 3338 min(-1) mM(-1) for CYP11B2, which is in the same order of magnitude as for the natural substrates but shows a preference of CYP11B2 for OT conversion. Products of OT metabolism by the CYP11B subfamily members were produced at a milligram scale with a recombinant Escherichia coli-based whole-cell system. They were identified by nuclear magnetic resonance spectroscopy to be 11β-OH-OT for both CYP11B isoforms, whereby CYP11B2 additionally formed 11β,18-diOH-OT and 11β-OH-OT-18-al, which rearranges to its tautomeric form 11β,18-expoxy-18-OH-OT. CYP11A1 produces six metabolites, which are proposed to include 2-OH-OT, 16-OH-OT, and 2,16-diOH-OT based on liquid chromatography-tandem mass spectrometry analyses. All three enzymes are shown to be inhibited by OT in their natural function. The extent of inhibition thereby depends on the affinity of the enzyme for OT and the strongest effect was demonstrated for CYP11B2. These findings suggest that steroidogenic cytochrome P450 enzymes can contribute to drug metabolism and should be considered in drug design and toxicity studies. Copyright © 2016 by The

  2. Genetic polymorphism of human cytochrome P-450 (S)-mephenytoin 4-hydroxylase. Studies with human autoantibodies suggest a functionally altered cytochrome P-450 isozyme as cause of the genetic deficiency

    Energy Technology Data Exchange (ETDEWEB)

    Meier, U.T.; Meyer, U.A.

    1987-12-15

    The metabolism of the anticonvulsant mephenytoin is subject to a genetic polymorphism. In 2-5% of Caucasians and 18-23% of Japanese subjects a specific cytochrome P-450 isozyme, P-450 meph, is functionally deficient or missing. The authors have accumulated evidence that autoimmune antibodies observed in sera of patients with tienilic acid induced hepatitis (anti-liver kidney microsome 2 or anti-LKM2 antibodies) specifically recognize the cytochrome P-450 involved in the mephrenytoin hydroxylation polymorphism. This is demonstrated by immunoinhibition and immunoprecipitation of microsomal (S)-mephenytoin 4-hydroxylation activity and by the recognition by anti-LKM2 antibodies of a single (/sup 125/I)-protein band on immunoblots of human liver microsomes after sodium dodecyl sulfate-polyacrylamide gel electrophoresis or isoelectric focusing. The cytochrome P-450 recognized by anti-LKM2 antibodies was immunopurified from microsomes derived from livers of extensive (EM) or poor metabolizers (PM) of (S)-mephenytoin. Comparison of the EM-type cytochrome P-450 to that isolated from PM livers revealed no difference in regard to immuno-cross-reactivity, molecular weight, isoelectric point, relative content in microsomes, two-dimensional tryptic peptide maps, one-dimensional peptide maps with three proteases, amino acid composition, and amino-terminal protein sequence. Finally, the same protein was precipitated from microsomes prepared from the liver biopsy of a subject phenotyped in vivo as a poor metabolizer of mephenytoin. These data strongly suggest that the mephenytoin hydroxylation deficiency is caused by a minor structural change leading to a functionally altered cytochrome P-450 isozyme.

  3. 23. Establishment of two transgenic cells stable expression of human cytochrome P450 2C

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    AIM: To clone the human cytochrome P450 2C9 (CYP2C9) and CYP2C18 cDNA and establish two transgenic CHL cell line stable expressing human CYP2C9 and CYP2C18. METHODS:Extracting total RNA from human liver tissue, the human CYP2C9 and CYP2C18 cDNA was amplified with reverse transcription polymerase chain reaction (RT-PCR), and cloned into cloning vector pGEM-T. The cDNA segment was identified by DNA sequencing and subcloned into a mammalian expression vector pREP9. Two transgenic cell line were established by transfecting the recombinant vectors of pREP9-CYP2C9 and pREP9-CYP2C18 to Chinese hamster lung cell CHL. The enzyme activity of CYP2C9 and CYP2C18 catalyze tolbutamide to 4-hydroxy tolbutamide in S9 protein of the cells were determinated by HPLC. RESULTS: The sequence of the two cDNA segments cloned, which were 1540 bp and 1671 bp in length, were identical to those reported by Romkes et al(GenBank accession number: M61855, M61856, J05326) in coding amino acids. The S9 fraction of the established cell lines can metabolize tolbutamide to 4-hydroxy tolbutamide, the tolbutamide-4-hydroxylase activity was found to be 0.465±0.109 and 0.509±0.052 nmol*min-1*(mg S9 protein)-1 (n=3), but was not detectable in parental CHL cell. CONCLUSION: The cDNA of CYP2C9 and CYP2C18 were successfolly cloned and cell lines of CHL-CYP2C9 and CHL-CYP2C18 which efficiently expressed the protein of CYP2C9 and CYP2C18 were established.

  4. Cytochrome P450 2A13 enhances the sensitivity of human bronchial epithelial cells to aflatoxin B1-induced DNA damage

    Energy Technology Data Exchange (ETDEWEB)

    Yang, Xuejiao [Key Lab of Modern Toxicology of Ministry of Education, School of Public Health, Nanjing Medical University, 818 East Tiangyuan Rd., Nanjing 211166 (China); Jiaojiang District Center for Disease Control and Prevention, 518 Jingdong Rd., Taizhou 318000 (China); Zhang, Zhan; Wang, Xichen; Wang, Yun; Zhang, Xiaoming; Lu, Huiyuan [Key Lab of Modern Toxicology of Ministry of Education, School of Public Health, Nanjing Medical University, 818 East Tiangyuan Rd., Nanjing 211166 (China); Wang, Shou-Lin, E-mail: wangshl@njmu.edu.cn [Key Lab of Modern Toxicology of Ministry of Education, School of Public Health, Nanjing Medical University, 818 East Tiangyuan Rd., Nanjing 211166 (China)

    2013-07-15

    Cytochrome P450 2A13 (CYP2A13) mainly expresses in human respiratory system and mediates the metabolic activation of aflatoxin B1 (AFB1). Our previous study suggested that CYP2A13 could increase the cytotoxic and apoptotic effects of AFB1 in immortalized human bronchial epithelial cells (BEAS-2B). However, the role of CYP2A13 in AFB1-induced DNA damage is unclear. Using BEAS-2B cells that stably express CYP2A13 (B-2A13), CYP1A2 (B-1A2), and CYP2A6 (B-2A6), we compared their effects in AFB1-induced DNA adducts, DNA damage, and cell cycle changes. BEAS-2B cells that were transfected with vector (B-vector) were used as a control. The results showed that AFB1 (5–80 nM) dose- and time-dependently induced DNA damage in B-2A13 cells. AFB1 at 10 and 80 nM significantly augmented this effect in B-2A13 and B-1A2 cells, respectively. B-2A6 cells showed no obvious DNA damage, similar to B-vector cells and the vehicle control. Similarly, compared with B-vector, B-1A2 or B-2A6 cells, B-2A13 cells showed more sensitivity in AFB1-induced γH2AX expression, DNA adduct 8-hydroxy-deoxyguanosine formation, and S-phase cell-cycle arrest. Furthermore, AFB1 activated the proteins related to DNA damage responses, such as ATM, ATR, Chk2, p53, BRCA1, and H2AX, rather than the proteins related to DNA repair. These effects could be almost completely inhibited by 100 μM nicotine (a substrate of CYP2A13) or 1 μM 8-methoxypsoralen (8-MOP; an inhibitor of CYP enzyme). Collectively, these findings suggest that CYP2A13 plays an important role in low-concentration AFB1-induced DNA damage, possibly linking environmental airborne AFB1 to genetic injury in human respiratory system. - Highlights: • CYP2A13 plays a critical role in low concentration of AFB1-induced DNA damage. • B-2A13 cells were more sensitive to AFB1 than B-1A2 cells and B-2A6 cells. • AFB1 dose- and time-dependently induced DNA damage in B-2A13 cells • AFB1-induced DNA adducts and damage can be inhibited by nicotine and 8

  5. Distinction between human cytochrome P450 (CYP) isoforms and identification of new phosphorylation sites by mass spectrometry

    DEFF Research Database (Denmark)

    Redlich, Gorden; Zanger, Ulrich M; Riedmaier, Stephan;

    2008-01-01

    In mammals, Cytochrome P450 (CYP) enzymes are bound to membranes of the endoplasmic reticulum and mitochondria, where they are responsible for the oxidative metabolism of many xenobiotics as well as organic endogenous compounds. In humans, 57 isoforms were identified which are classified based...

  6. Thalidomide increases human hepatic cytochrome P450 3A enzymes by direct activation of the pregnane X receptor.

    Science.gov (United States)

    Murayama, Norie; van Beuningen, Rinie; Suemizu, Hiroshi; Guguen-Guillouzo, Christiane; Shibata, Norio; Yajima, Kanako; Utoh, Masahiro; Shimizu, Makiko; Chesné, Christophe; Nakamura, Masato; Guengerich, F Peter; Houtman, René; Yamazaki, Hiroshi

    2014-02-17

    Heterotropic cooperativity of human cytochrome P450 (P450) 3A4/3A5 by the teratogen thalidomide was recently demonstrated by H. Yamazaki et al. ( ( 2013 ) Chem. Res. Toxicol. 26 , 486 - 489 ) using the model substrate midazolam in various in vitro and in vivo models. Chimeric mice with humanized liver also displayed enhanced midazolam clearance upon pretreatment with orally administered thalidomide, presumably because of human P450 3A induction. In the current study, we further investigated the regulation of human hepatic drug metabolizing enzymes. Thalidomide enhanced levels of P450 3A4 and 2B6 mRNA, protein expression, and/or oxidation activity in human hepatocytes, indirectly suggesting the activation of upstream transcription factors involved in detoxication, e.g., the nuclear receptors pregnane X receptor (PXR) and constitutive androstane receptor (CAR). A key event after ligand binding is an alteration of nuclear receptor conformation and recruitment of coregulator proteins that alter chromatin accessibility of target genes. To investigate direct engagement and functional alteration of PXR and CAR by thalidomide, we utilized a peptide microarray with 154 coregulator-derived nuclear receptor-interaction motifs and coregulator and nuclear receptor boxes, which serves as a sensor for nuclear receptor conformation and activity status as a function of ligand. Thalidomide and its human proximate metabolite 5-hydroxythalidomide displayed significant modulation of coregulator interaction with PXR and CAR ligand-binding domains, similar to established agonists for these receptors. These results collectively suggest that thalidomide acts as a ligand for PXR and CAR and causes enzyme induction leading to increased P450 enzyme activity. The possibilities of drug interactions during thalidomide therapy in humans require further evaluation.

  7. Progress on research of the alternative splicing of human cytochrome P450 pre-mRNA%人细胞色素P450前mRNA的可变剪接研究进展

    Institute of Scientific and Technical Information of China (English)

    诸葛坚; 余应年

    2005-01-01

    Human genes typically contain multiple introns, and in many cases the exons can be joined more than one way to generate multiple rnRNAs, encoding distinct protein isoforms. This process is called alternative splicing. The article summarized the human cytochrome P450 pre-mRNA alternative splicing and their regulatory mechanism and impacts on biological functions.

  8. In vitro evaluation of hepatotoxic drugs in human hepatocytes from multiple donors: Identification of P450 activity as a potential risk factor for drug-induced liver injuries.

    Science.gov (United States)

    Utkarsh, Doshi; Loretz, Carol; Li, Albert P

    2016-08-01

    A possible risk factor for drug-induced hepatotoxicity is drug metabolizing enzyme activity, which is known to vary among individuals due to genetic (genetic polymorphism) and environmental factors (environmental pollutants, foods, and medications that are inhibitors or inducers of drug metabolizing enzymes). We hypothesize that hepatic cytochrome P450-dependent monooxygenase (CYP) activity is one of the key risk factors for drug induced liver injuries (DILI) in the human population, especially for drugs that are metabolically activated to cytotoxic/reactive metabolites. Human hepatocytes from 19 donors were evaluated for the activities of 8 major P450 isoforms: CYP1A2, CYP2B6, CYP2C8, CYP2C9, CYP2C19, CYP2D6, CYP2E1 and CYP3A4. Extensive individual variations were observed, consistent with what is known to be in the human population. As CYP3A4 is known to be one of the most important P450 isoforms for drug metabolism, studies were performed to evaluate the relationship between the in vitro cytotoxicity of hepatotoxic drugs and CYP3A4 activity. In a proof of concept study, hepatocytes from six donors (lots) representing the observed range of CYP3A4 activities were chosen for the evaluation of in vitro hepatotoxicity of four drugs known to be associated with acute liver failure: acetaminophen, cyclophosphamide, ketoconazole, and tamoxifen. The hepatocytes were cultured in collagen-coated plates and treated with the hepatotoxicants for approximately 24 h, followed by viability determination based on cellular adenosine triphosphate (ATP) contents. HH1023, the lot of hepatocytes with the highest CYP3A4 activity, was found to be the most sensitive to the cytotoxicity of all 4 hepatotoxic drugs, thereby suggesting that high CYP3A4 activity may be a risk factor. To further validate the relationship, a second study was performed with hepatocytes from 16 donors. In this study, the hepatocytes were quantified for CYP3A4 activity at the time of treatment. Results of the

  9. 淫羊藿总黄酮对大鼠肝微粒体CYP1A2、CYP3A4和CYP2E1活性的影响%Effect of total flavonoids of epimedium on liver microsomal CYP1A2, CYP3A4 and CYP2E1 activities in rats

    Institute of Scientific and Technical Information of China (English)

    胡道德; 姚慧娟; 顾磊; 王松坡; 刘皋林

    2008-01-01

    To assess the potential effect of total flavonoids of epimedium (TFE) on cytochrome P450 and activity of its main isoforms in rat liver microsomes. TFE (300 mg/kg) was administered once daily to male Sprague-Dowley rats by gavage for fifteen days. The total cytochrome P450 content and its main isoforms CYP1A2, CYP3A4 and CYP2E1 activities in rat liver microsomes were detected. The activity of CYP1A2 was measured by fluorometry and the activities of CYP3A4 and CYP2E1 were determined by measuring the amount of methanal and p-aminophenol formed using UV/Vis spectrophotometer, respec- tively. Administration of TFE significantly increased the total CYP450 content and activities of CYP 1A2, CYP3A4 and CYP2E1 in rat liver microsomes, compared with the control group. Partieularly, the activities of CYP1A2 and CYP2E1 were enhanced significantly (P<0.01). TFE induced the increase in total CYP450 content and its main isoforms CYP1A2, CYP3A4 and CYP2EI activities in rat liver microsomes.%评估淫羊藿总黄酮对大鼠肝细胞色素P450及其主要亚型活性的潜在影响.淫羊藿总黄酮以300 mg/kg/d的剂量对SD大鼠进行连续灌胃处理15天,测定肝微粒体中CYP450含量与CYP1A2、CYP3A4和CYP2E1亚型活性,观察淫羊藿总黄酮的效应.CYP1A2的活性用荧光比色法进行测定,CYP3A4和CYP2E1的活性用紫外可见分光光度法测定.淫羊藿总黄酮处理后的大鼠肝脏CYP450含量及CYP1A2、CYP3A4和LICYP2E1亚型活性均明显增高,其中CYP1A2和CYP2E1活性升高显著(P<0.01).淫羊藿总黄酮对大鼠肝脏CYP450及主要亚型CYP1A2、CYP3A4和CYP2E1活性均有诱导效应.

  10. Human plasma concentrations of cytochrome P450 probes extrapolated from pharmacokinetics in cynomolgus monkeys using physiologically based pharmacokinetic modeling.

    Science.gov (United States)

    Shida, Satomi; Utoh, Masahiro; Murayama, Norie; Shimizu, Makiko; Uno, Yasuhiro; Yamazaki, Hiroshi

    2015-01-01

    1. Cynomolgus monkeys are widely used in preclinical studies as non-human primate species. Pharmacokinetics of human cytochrome P450 probes determined in cynomolgus monkeys after single oral or intravenous administrations were extrapolated to give human plasma concentrations. 2. Plasma concentrations of slowly eliminated caffeine and R-/S-warfarin and rapidly eliminated omeprazole and midazolam previously observed in cynomolgus monkeys were scaled to human oral biomonitoring equivalents using known species allometric scaling factors and in vitro metabolic clearance data with a simple physiologically based pharmacokinetic (PBPK) model. Results of the simplified human PBPK models were consistent with reported experimental PK data in humans or with values simulated by a fully constructed population-based simulator (Simcyp). 3. Oral administrations of metoprolol and dextromethorphan (human P450 2D probes) in monkeys reportedly yielded plasma concentrations similar to their quantitative detection limits. Consequently, ratios of in vitro hepatic intrinsic clearances of metoprolol and dextromethorphan determined in monkeys and humans were used with simplified PBPK models to extrapolate intravenous PK in monkeys to oral PK in humans. 4. These results suggest that cynomolgus monkeys, despite their rapid clearance of some human P450 substrates, could be a suitable model for humans, especially when used in conjunction with simple PBPK models.

  11. Oxidation of N-Nitrosoalkylamines by Human Cytochrome P450 2A6

    Science.gov (United States)

    Chowdhury, Goutam; Calcutt, M. Wade; Guengerich, F. Peter

    2010-01-01

    Cytochrome P450 (P450) 2A6 activates nitrosamines, including N,N-dimethylnitrosamine (DMN) and N,N-diethylnitrosamine (DEN), to alkyl diazohydroxides (which are DNA-alkylating agents) and also aldehydes (HCHO from DMN and CH3CHO from DEN). The N-dealkylation of DMN had a high intrinsic kinetic deuterium isotope effect (Dkapp ∼ 10), which was highly expressed in a variety of competitive and non-competitive experiments. The Dkapp for DEN was ∼3 and not expressed in non-competitive experiments. DMN and DEN were also oxidized to HCO2H and CH3CO2H, respectively. In neither case was a lag observed, which was unexpected considering the kcat and Km parameters measured for oxidation of DMN and DEN to the aldehydes and for oxidation of the aldehydes to the carboxylic acids. Spectral analysis did not indicate strong affinity of the aldehydes for P450 2A6, but pulse-chase experiments showed only limited exchange with added (unlabeled) aldehydes in the oxidations of DMN and DEN to carboxylic acids. Substoichiometric kinetic bursts were observed in the pre-steady-state oxidations of DMN and DEN to aldehydes. A minimal kinetic model was developed that was consistent with all of the observed phenomena and involves a conformational change of P450 2A6 following substrate binding, equilibrium of the P450-substrate complex with a non-productive form, and oxidation of the aldehydes to carboxylic acids in a process that avoids relaxation of the conformation following the first oxidation (i.e. of DMN or DEN to an aldehyde). PMID:20061389

  12. Metabolism of bilirubin by human cytochrome P450 2A6

    Energy Technology Data Exchange (ETDEWEB)

    Abu-Bakar, A' edah, E-mail: a.abubakar@uq.edu.au [The University of Queensland, National Research Centre for Environmental Toxicology (Entox), 4072 Brisbane, Queensland (Australia); Arthur, Dionne M. [The University of Queensland, National Research Centre for Environmental Toxicology (Entox), 4072 Brisbane, Queensland (Australia); Cooperative Research Centre for Contamination Assessment and Remediation of the Environment, Adelaide (Australia); Wikman, Anna S. [The University of Queensland, National Research Centre for Environmental Toxicology (Entox), 4072 Brisbane, Queensland (Australia); Department of Pharmaceutical Biosciences, Uppsala University, SE-75123 Uppsala (Sweden); Rahnasto, Minna; Juvonen, Risto O.; Vepsäläinen, Jouko; Raunio, Hannu [School of Pharmacy, Faculty of Health Sciences, University of Eastern Finland, POB 1627, 70211 Kuopio (Finland); Ng, Jack C. [The University of Queensland, National Research Centre for Environmental Toxicology (Entox), 4072 Brisbane, Queensland (Australia); Cooperative Research Centre for Contamination Assessment and Remediation of the Environment, Adelaide (Australia); Lang, Matti A. [The University of Queensland, National Research Centre for Environmental Toxicology (Entox), 4072 Brisbane, Queensland (Australia)

    2012-05-15

    The mouse cytochrome P450 (CYP) 2A5 has recently been shown to function as hepatic “Bilirubin Oxidase” (Abu-Bakar, A., et al., 2011. Toxicol. Appl. Pharmacol. 257, 14–22). To date, no information is available on human CYP isoforms involvement in bilirubin metabolism. In this paper we provide novel evidence for human CYP2A6 metabolising the tetrapyrrole bilirubin. Incubation of bilirubin with recombinant yeast microsomes expressing the CYP2A6 showed that bilirubin inhibited CYP2A6-dependent coumarin 7-hydroxylase activity to almost 100% with an estimated K{sub i} of 2.23 μM. Metabolite screening by a high-performance liquid chromatography/electrospray ionisation mass spectrometry indicated that CYP2A6 oxidised bilirubin to biliverdin and to three other smaller products with m/z values of 301, 315 and 333. Molecular docking analyses indicated that bilirubin and its positively charged intermediate interacted with key amino acid residues at the enzyme's active site. They were stabilised at the site in a conformation favouring biliverdin formation. By contrast, the end product, biliverdin was less fitting to the active site with the critical central methylene bridge distanced from the CYP2A6 haem iron facilitating its release. Furthermore, bilirubin treatment of HepG2 cells increased the CYP2A6 protein and activity levels with no effect on the corresponding mRNA. Co-treatment with cycloheximide (CHX), a protein synthesis inhibitor, resulted in increased half-life of the CYP2A6 compared to cells treated only with CHX. Collectively, the observations indicate that the CYP2A6 may function as human “Bilirubin Oxidase” where bilirubin is potentially a substrate and a regulator of the enzyme. -- Highlights: ► Human CYP2A6 interacts with bilirubin with a high affinity. ► Bilirubin docking to the CYP2A6 active site is more stable than biliverdin docking. ► Recombinant CYP2A6 microsomes metabolised bilirubin to biliverdin. ► Bilirubin increased the hepatic

  13. Global (Q)SAR models on substrates for human Cytochrome P450 3A4

    DEFF Research Database (Denmark)

    Ringsted, Tine; Nikolov, Nikolai Georgiev; Wedebye, Eva Bay;

    The Cytochrome P450 (CYP) is a superfamily of enzymes which catalyze the metabolism of a wide range of endobiotics and xenobiotics. The latter category comprises drugs and about 75% of marketed drugs are metabolised by CYP enzymes. Besides drugs, CYP enzymes detoxify environmental compounds...... domain. Domain coverage of EINECS chemicals and number of predicted substrates are discussed. Reference: C.W. Yap and Y.Z. Chen, Prediction of cytochrome p450 3A4, 2D6, and 2C9 inhibitors and substrates by using support vector machines, J. Chem. Inf. Model. 45 (2005), pp. 982–992....... but paradoxically they also have the ability to form reactive intermediates which can damage DNA, lipids and proteins. It is therefore important to gain knowledge on which substrates that can potentially be metabolised by CYP. The CYP 3A4 isoenzyme plays a dominant role by the metabolic elimination of up to 35...

  14. Estimation of the binding modes with important human cytochrome P450 enzymes, drug interaction potential, pharmacokinetics, and hepatotoxicity of ginger components using molecular docking, computational, and pharmacokinetic modeling studies.

    Science.gov (United States)

    Qiu, Jia-Xuan; Zhou, Zhi-Wei; He, Zhi-Xu; Zhang, Xueji; Zhou, Shu-Feng; Zhu, Shengrong

    2015-01-01

    Ginger is one of the most commonly used herbal medicines for the treatment of numerous ailments and improvement of body functions. It may be used in combination with prescribed drugs. The coadministration of ginger with therapeutic drugs raises a concern of potential deleterious drug interactions via the modulation of the expression and/or activity of drug-metabolizing enzymes and drug transporters, resulting in unfavorable therapeutic outcomes. This study aimed to determine the molecular interactions between 12 main active ginger components (6-gingerol, 8-gingerol, 10-gingerol, 6-shogaol, 8-shogaol, 10-shogaol, ar-curcumene, β-bisabolene, β-sesquiphelandrene, 6-gingerdione, (-)-zingiberene, and methyl-6-isogingerol) and human cytochrome P450 (CYP) 1A2, 2C9, 2C19, 2D6, and 3A4 and to predict the absorption, distribution, metabolism, excretion, and toxicity (ADMET) of the 12 ginger components using computational approaches and comprehensive literature search. Docking studies showed that ginger components interacted with a panel of amino acids in the active sites of CYP1A2, 2C9, 2C19, 2D6, and 3A4 mainly through hydrogen bond formation, to a lesser extent, via π-π stacking. The pharmacokinetic simulation studies showed that the [I]/[Ki ] value for CYP2C9, 2C19, and 3A4 ranged from 0.0002 to 19.6 and the R value ranged from 1.0002 to 20.6 and that ginger might exhibit a high risk of drug interaction via inhibition of the activity of human CYP2C9 and CYP3A4, but a low risk of drug interaction toward CYP2C19-mediated drug metabolism. Furthermore, it has been evaluated that the 12 ginger components possessed a favorable ADMET profiles with regard to the solubility, absorption, permeability across the blood-brain barrier, interactions with CYP2D6, hepatotoxicity, and plasma protein binding. The validation results showed that there was no remarkable effect of ginger on the metabolism of warfarin in humans, whereas concurrent use of ginger and nifedipine exhibited a

  15. Cytochrome P450 gene polymorphism and cancer.

    Science.gov (United States)

    Agundez, Jose A G

    2004-06-01

    Human cytochrome P450 (CYP) enzymes play a key role in the metabolism of drugs and environmental chemicals. Several CYP enzymes metabolically activate procarcinogens to genotoxic intermediates. Phenotyping analyses revealed an association between CYP enzyme activity and the risk to develop several forms of cancer. Research carried out in the last decade demonstrated that several CYP enzymes are polymorphic due to single nucleotide polymorphisms, gene duplications and deletions. As genotyping procedures became available for most human CYP, an impressive number of association studies on CYP polymorphisms and cancer risk were conducted. Here we review the findings obtained in these studies regarding CYP1A1, CYP1A2, CYP1B1, CYP2A6, CYP2B6, CYP2C8, CYP2C9, CYP2C18, CYP2C19, CYP2D6, CYP2E1, CYP3A4, CYP3A5, CYP3A7, CYP8A1 and CYP21 gene polymorphisms. Consistent evidences for association between CYP polymorphisms and lung, head and neck, and liver cancer were reported. Controversial findings suggest that colorectal and prostate cancers may be associated to CYP polymorphisms, whereas no evidences for a relevant association with breast or bladder cancers were reported. We summarize the available information related to the association of CYP polymorphisms with leukaemia, lymphomas and diverse types of cancer that were investigated only for some CYP genes, including brain, esophagus, stomach, pancreas, pituitary, cervical epithelium, melanoma, ovarian, kidney, anal and vulvar cancers. This review discusses on causes of heterogeneity in the proposed associations, controversial findings on cancer risk, and identifies topics that require further investigation. In addition, some recommendations on study design, in order to obtain more conclusive findings in further studies, are provided.

  16. Development of an on-line high performance liquid chromatography detection system for human cytochrome P450 1A2 inhibitors in extracts of natural products

    NARCIS (Netherlands)

    Jeurissen, S.M.F.; Claassen, F.W.; Havlik, J.; Bouwmans, E.E.; Cnubben, N.H.P.; Sudhölter, E.J.R.; Rietjens, I.M.C.M.; Beek, T.A. van

    2007-01-01

    An on-line HPLC screening method for detection of inhibitors of human cytochrome P450 1A2 in extracts was developed. HPLC separation of extracts is connected to a continuous methoxyresorufin-O-demethylation (MROD) assay in which recombinant human P450 1A2 converts methoxyresorufin to its fluorescent

  17. Neoplastic lesions of the human liver in relation to the activity of the cytochrome P-450 dependent monooxygenase system.

    Science.gov (United States)

    Plewka, D; Plewka, A; Nowaczyk, G; Kamiński, M; Rutkowski, T; Ludyga, T; Ziaja, K

    2000-01-01

    We studied the activity of Mixed function oxidase (MFO) in human livers affected by cancer. We determined the content of cytochrome P-450 and b5, as well as the activity of their corresponding reductases, according to generally accepted methods. Liver fragments corresponding with a) healthy tissue, b) tissue at the cancer border and, c) cancerous tissue were collected during surgery from patients with liver cancer. We noted that the developing liver cancer decreased the level of cytochrome P-450, even by a magnitude order. The activity of its corresponding reductase was higher in cancerous than in healthy tissues. Cytochrome b5 behaved in an analogous manner, although the decrease in its content was less significant. NADH-cytochrome b5 reductase activity changes were insignificant.

  18. Characterization of the cytochrome P450 enzymes involved in the metabolism of a new cardioprotective agent KR-33028.

    Science.gov (United States)

    Kim, Hyojin; Yoon, Yune-Jung; Kim, Hyunmi; Kang, Suil; Cheon, Hyae Gyeong; Yoo, Sung-Eun; Shin, Jae-Gook; Liu, Kwang-Hyeon

    2006-10-10

    KR-33028 (N-[4-cyano-benzo[b]thiophene-2-carbonyl]guanidine) is a new cardioprotective agent for preventing ischemia-reperfusion injury. This study was performed to characterize the cytochrome P450 (CYP) enzymes that are involved in the metabolism of KR-33028. Hydroxylation (5-hydroxy- and 7-hydroxy-KR-33028) is major pathways for the metabolism of KR-33028 in human liver microsomes. Among the nine c-DNA expressed CYP isoforms tested, KR-33028 was 5-hydroxylated by CYP3A4 and 7-hydroxylated by CYP1A2, CYP3A4, and CYP2C19. These findings were supported by the combination of chemical inhibition studies in human liver microsomes and correlation analysis. Furafylline and ketoconazole potently inhibited hydroxylation of KR-33028 in human liver microsomes. Correlation analysis between the known CYP enzyme activities and the rates of the formation of 5-hydroxy- and 7-hydroxy-KR-33028 in the 16 human liver microsomes has showed significant correlations with CYP3A4-mediated midazolam 1'-hydroxylation and CYP1A2-mediated phenacetin O-deethylation, respectively. A 7-hydroxy-KR-33028 formation is also weakly correlated with CYP3A4-mediated midazolam 1'-hydroxylation. The kinetics of the major biotransformation of KR-33028 were studied: CYP3A4 mediated the formation of 5-hydroxy-KR-33028 from KR-33028 with Cl(int)=0.22microl/min/pmol CYP. The intrinsic clearance for 7-hydroxy-KR-33028 formation by CYP1A2, CYP2C19, and CYP3A4 were 0.26, 0.19, and 0.03microl/min/pmol CYP, respectively. Taken together, these results provide evidence that CYP3A4 and CYP1A2 are the major isoforms responsible for the hydroxy metabolites formation from KR-33028.

  19. CYP1A2 phenotyping in dried blood spots and microvolumes of whole blood and plasma.

    Science.gov (United States)

    De Kesel, Pieter M M; Lambert, Willy E; Stove, Christophe P

    2014-01-01

    Phenotyping, using caffeine as probe substrate, is a proper method to assess CYP1A2 activity. We evaluated the utility of dried blood spots (DBS) for CYP1A2 phenotyping. LC-MS/MS methods were developed and validated for quantitation of caffeine and its metabolite paraxanthine in DBS, whole blood and plasma. All parameters met the pre-established criteria. While recovery, matrix effects and precision were unaffected by hematocrit (Hct), there was a Hct effect on accuracy, although for the evaluated Hct interval (0.36-0.50) it remained within acceptable limits. The phenotyping methods were successfully applied in healthy volunteers. Excellent method performance and highly comparable phenotyping indices in DBS, whole blood and plasma, combined with the benefits of DBS sampling, illustrate the suitability of DBS-based CYP1A2 phenotyping.

  20. Cytochrome p450 part 2: what nurses need to know about the cytochrome p450 family systems.

    Science.gov (United States)

    Krau, Stephen D

    2013-12-01

    To provide the best patient care related to medication administration and prescription, an understanding of the specific enzymes is essential. Enzymes affect the metabolizing of most medications that nurses administer and that nurse practitioners and physicians prescribe on a regular basis. More specifically, the most important p450 enzymes in drug metabolism are cytochrome p450 (CYP) 1A2, the CYP2C family, CYP2D6, and CYP3A4. In addition, the enzymes are instrumental in the body's reaction to environmental factors, some of which are carcinogens. Copyright © 2013 Elsevier Inc. All rights reserved.

  1. Inhibition of fipronil and nonane metabolism in human liver microsomes and human cytochrome P450 isoforms by chlorpyrifos.

    Science.gov (United States)

    Joo, Hyun; Choi, Kyoungju; Rose, Randy L; Hodgson, Ernest

    2007-01-01

    Previous studies have established that chlorpyrifos (CPS), fipronil, and nonane can all be metabolized by human liver microsomes (HLM) and a number of cytochrome P450 (CYP) isoforms. However, metabolic interactions between these three substrates have not been described. In this study the effect of either coincubation or preincubation of CPS with HLM or CYP isoforms with either fipronil or nonane as substrate was investigated. In both co- and preincubation experiments, CPS significantly inhibited the metabolism of fipronil or nonane by HLM although CPS inhibited the metabolism of fipronil more effectively than that of nonane. CPS significantly inhibited the metabolism of fipronil by CYP3A4 as well as the metabolism of nonane by CYP2B6. In both cases, preincubation with CPS caused greater inhibition than coincubation, suggesting that the inhibition is mechanism based.

  2. 细胞色素P450基因多态性与药物代谢%Genetic Polymorphisms of Human Cytochrome P450: Relevance to Drug Metabolism

    Institute of Scientific and Technical Information of China (English)

    盛海辉; 肖华胜

    2008-01-01

    细胞色素P450(cytochrome P450,CYP)在众多外源性和内源性物质的代谢中具有重要作用.CYP家族1-3中编码P450的基因均存在多态性,特别是CYP2C9、CYP2C19、CYP2D6和CYP3A5.超过一半的临床药物是由多态性P450介导代谢,CYP基因的多态性是造成药物反应个体差异的主要原因.近几年,许多与P450酶活性和CYP基因表达相关的等位基因已被鉴定,因此通过分型CYP基因的功能性或标签(Tag)的遗传变异,就可以获得个体的代谢表型,有助于医生及时找到正确的用药方案,有效地提高药物疗效和降低毒副作用,特别是那些治疗指数窄的药物.显然,了解CYP基因的遗传变异对于临床药物治疗和药物开发是必不可少的.基因芯片技术具有高多重水平和高通量的特点,使同时分型大量CYP基因遗传变异成为可能,是实现个性化医疗的重要技术保障.然而,DNA制备制约了预测性CYP基因分型芯片的发展,其在临床上的广泛应用尚需时日.%The human cytochrome P450 (CYP) enzymes play critical roles in the metabolism of numerous exogenous and endogenous molecules. All genes encoding P450 in families 1-3 are polymorphic,particularly CYP2C9,CYP2C19,CYP2D6 and CYP3A5. Polymorphic P450s are involved in the metabolism of more than 50% of clinical drugs. Genetic variation in the CYP genes is he main cause for individual variation in drug response. Over the past several years,Alleles are responsible for the variable enzymatic activity of P450 and the variable expression of CYP genes,have been identified. The phenotype can be determined by genotyping the functional variants or tag variants of the CYP genes. This helps doctors to choose ppropriate medication for patients to enhance the curative effect and to reduce the side effect,especially when drugs with narrow therapeutic index are involved. Knowledge of genetic variants of the CYP genes is necessary for both drug therapy and drug development. With a

  3. Biotransformation of 2,2',4,4'-tetrabromodiphenyl ether (BDE-47) by human liver microsomes: identification of cytochrome P450 2B6 as the major enzyme involved.

    Science.gov (United States)

    Erratico, Claudio A; Szeitz, András; Bandiera, Stelvio M

    2013-05-20

    Polybrominated diphenyl ethers (PBDEs) were widely used flame retardants that have become persistent environmental pollutants. In the present study, we investigated the in vitro oxidative metabolism of 2,2',4,4'-tetrabromodiphenyl ether (BDE-47), a major PBDE detected in human tissue and environmental samples. Biotransformation of BDE-47 by pooled and individual human liver microsomes and by human recombinant cytochrome P450 (P450) enzymes was assessed using a liquid chromatography/tandem mass spectrometry-based method. Of the nine hydroxylated metabolites of BDE-47 produced by human liver microsomes, seven metabolites were identified using authentic standards. A monohydroxy-tetrabrominated and a dihydroxy-tetrabrominated metabolite remain unidentified. Kinetic analysis of the rates of metabolite formation revealed that the major metabolites were 5-hydroxy-2,2',4,4'-tetrabromodiphenyl ether (5-OH-BDE-47), 6-hydroxy-2,2',4,4'-tetrabromodiphenyl ether (6-OH-BDE-47), and possibly the unidentified monohydroxy-tetrabrominated metabolite. Among the human recombinant P450 enzymes tested, P450 2B6 was the most active enzyme in the formation of the hydroxylated metabolites of BDE-47. Moreover, the formation of all metabolites of BDE-47 by pooled human liver microsomes was inhibited by a P450 2B6-specific antibody and was highly correlated with P450 2B6-mediated activity in single donor liver microsomes indicating that P450 2B6 was the major P450 responsible for the biotransformation of BDE-47. Additional experiments involving the incubation of liver microsomes with individual monohydroxy-tetrabrominated metabolites in place of BDE-47 demonstrated that 2,4-dibromophenol was a product of BDE-47 and several primary metabolites, but the dihydroxy-tetrabrominated metabolite was not formed by sequential hydroxylation of any of the monohydroxy-tetrabrominated metabolites tested. The present study provides a comprehensive characterization of the oxidative metabolism of BDE-47 by

  4. Evaluation of the Effects of Mitragyna speciosa Alkaloid Extract on Cytochrome P450 Enzymes Using a High Throughput Assay

    Directory of Open Access Journals (Sweden)

    Raja Elina Raja Aziddin

    2011-08-01

    Full Text Available The extract from Mitragyna speciosa has been widely used as an opium substitute, mainly due to its morphine-like pharmacological effects. This study investigated the effects of M. speciosa alkaloid extract (MSE on human recombinant cytochrome P450 (CYP enzyme activities using a modified Crespi method. As compared with the liquid chromatography-mass spectrometry method, this method has shown to be a fast and cost-effective way to perform CYP inhibition studies. The results indicated that MSE has the most potent inhibitory effect on CYP3A4 and CYP2D6, with apparent half-maximal inhibitory concentration (IC50 values of 0.78 µg/mL and 0.636 µg/mL, respectively. In addition, moderate inhibition was observed for CYP1A2, with an IC50 of 39 µg/mL, and weak inhibition was detected for CYP2C19. The IC50 of CYP2C19 could not be determined, however, because inhibition was < 50%. Competitive inhibition was found for the MSE-treated CYP2D6 inhibition assay, whereas non-competitive inhibition was shown in inhibition assays using CYP3A4, CYP1A2 and CYP2C19. Quinidine (CYP2D6, ketoconazole (CYP3A4, tranylcypromine (CYP2C19 and furafylline (CYP1A2 were used as positive controls throughout the experiments. This study shows that MSE may contribute to an herb-drug interaction if administered concomitantly with drugs that are substrates for CYP3A4, CYP2D6 and CYP1A2.

  5. [In vivo evaluation of the metabolic ratio of CYP2C9 and CYP1A2 drug markers after administration of afobazole in comparison to standard inducers and inhibitors of cytochromes].

    Science.gov (United States)

    Novitskaia, Ia G; Gribakina, O G; Kolyvanov, G B; Zherdev, V P; Smirnov, V V; Seredenin, S B

    2013-01-01

    The effect of subchronic peroral administration in effective doses of afobazole (5 mg/kg), and cytochrome P450 inductors (rifampicin, 13.4 mg/kg; phenytoin, 10.4 mg/kg) and inhibitors (fluconazole, 35.7 mg/kg; ciprofloxacin, 44.0 mg/kg) on the metabolic ratio (MR) of drugs-markers of CYP2C9 and CYP1A2 activity was studied in rats. Afobazole did not change the MR of compounds metabolized by the P450 isoforms studied. After peroral administration of standard P450 inductors and inhibitors, statistically significant bidirectional effects were identified, which demonstrated the expedience of administering a complex of selected compounds, markers, and CYP2C9 and CYP1A2 activity modificators for comparative evaluation of the effects of new drugs in rats. It is recommended to evaluate the activity of CYP1A2 by determining the MR for one of two caffeine metabolites, paraxanthine or theobromine, and the activity of CYP2C9 by determining the MR of metabolite Exp-3174 to losartan.

  6. Effects of 3G cell phone exposure on the structure and function of the human cytochrome P450 reductase.

    Science.gov (United States)

    Tanvir, Shazia; Thuróczy, György; Selmaoui, Brahim; Silva Pires Antonietti, Viviane; Sonnet, Pascal; Arnaud-Cormos, Delia; Lévêque, Philippe; Pulvin, Sylviane; de Seze, René

    2016-10-01

    Cell phones increase exposure to radiofrequency (RF) electromagnetic fields (EMFs). Whether EMFs exert specific effects on biological systems remains debatable. This study investigated the effect of cell phone exposure on the structure and function of human NADPH-cytochrome P450 reductase (CPR). CPR plays a key role in the electron transfer to cytochrome P450, which takes part in a wide range of oxidative metabolic reactions in various organisms from microbes to humans. Human CPR was exposed for 60min to 1966-MHz RF inside a transverse electromagnetic cell (TEM-cell) placed in an incubator. The specific absorption rate (SAR) was 5W·kg(-1). Conformation changes have been detected through fluorescent spectroscopy of flavin and tryptophan residues, and investigated through circular dichroism, dynamic light scattering and microelectrophoresis. These showed that CPR was narrowed. By using cytochrome C reductase activity to assess the electron flux through the CPR, the Michaelis Menten constant (Km) and the maximum initial velocity (Vmax) decreased by 22% as compared with controls. This change was due to small changes in the tertiary and secondary structures of the protein at 37°C. The relevance of these findings to an actual RF exposure scenario demands further biochemical and in-vivo confirmation.

  7. Echinacea purpurea up-regulates CYP1A2, CYP3A4 and MDR1 gene expression by activation of pregnane X receptor pathway.

    Science.gov (United States)

    Awortwe, Charles; Manda, Vamshi K; Avonto, Cristina; Khan, Shabana I; Khan, Ikhlas A; Walker, Larry A; Bouic, Patrick J; Rosenkranz, Bernd

    2015-03-01

    1.This study investigated the mechanism underlying Echinacea-mediated induction of CYP1A2, CYP3A4 and MDR1 in terms of human pregnane X receptor (PXR) activation. 2.Crude extracts and fractions of Echinacea purpurea were tested for PXR activation in HepG2 cells by a reporter gene assay. Quantitative real-time PCR was carried out to determine their effects on CYP1A2 and CYP3A4 mRNA expressions. Capsules and fractions were risk ranked as high, intermediate and remote risk of drug-metabolizing enzymes induction based on EC50 values determined for respective CYPs. 3. Fractions F1, F2 and capsule (2660) strongly activated PXR with 5-, 4- and 3.5-fold increase in activity, respectively. Echinacea preparations potentiated up-regulation of CYP1A2, CYP3A4 and MDR1 via PXR activation. 4.Thus E. purpurea preparations cause herb-drug interaction by up-regulating CYP1A2, CYP3A4 and P-gp via PXR activation.

  8. Development and validation of a reversed-phase HPLC method for CYP1A2 phenotyping by use of a caffeine metabolite ratio in saliva.

    Science.gov (United States)

    Begas, Elias; Kouvaras, Evangelos; Tsakalof, Andreas K; Bounitsi, Maria; Asprodini, Eftihia Konstadinos

    2015-11-01

    CYP1A2 is important for metabolizing various clinically used drugs. Phenotyping of CYP1A2 may prove helpful for drug individualization therapy. Several HPLC methods have been developed for quantification of caffeine metabolites in plasma and urine. Aim of the present study was to develop a valid and simple HPLC method for evaluating CYP1A2 activity during exposure in xenobiotics by the use of human saliva. Caffeine and paraxanthine were isolated from saliva by liquid-liquid extraction (chlorophorm/isopropanol 85/15v/v). Extracts were analyzed by reversed-phase HPLC on a C18 column with mobile phase 0.1% acetic acid/methanol/acetonitrile (80/20/2 v/v) and detected at 273nm. Caffeine and paraxanthine elution times were caffeine metabolites. Detector response was linear (0.10-8.00µg/ml, R(2) >0.99), recovery was >93% and bias caffeine. Paraxanthine/caffeine ratio of 34 healthy volunteers was significantly higher in smokers (pcaffeine ratios and urine metabolite ratios were highly correlated (r=0.85, p<0.001). The method can be used for the monitoring of CYP1A2 activity in clinical practice and in studies relevant to exposure to environmental and pharmacological xenobiotics.

  9. P450-aromatase activity and expression in human testicular tissues with severe spermatogenic failure.

    Science.gov (United States)

    Lardone, M C; Castillo, P; Valdevenito, R; Ebensperger, M; Ronco, A M; Pommer, R; Piottante, A; Castro, A

    2010-08-01

    There is evidence that impaired spermatogenesis is associated with an imbalance in the oestradiol/testosterone ratio and with Leydig cell (LC) dysfunction. In testis, P450-aromatase, encoded by CYP19, is responsible for the conversion of testosterone to oestradiol. The aims of this study were to quantify CYP19 mRNA expression, aromatase activity and protein localization, and to measure the oestradiol to testosterone ratio in testicular tissues of men with spermatogenic impairment. Twenty-four men with complete Sertoli cell-only syndrome (SCOS), 14 with focal SCOS, 14 with maturation arrest (MA), 8 with mixed atrophy and 30 controls with normal spermatogenesis were subjected to testicular biopsy. All subjects underwent a physical examination, cytogenetic and serum hormonal studies. Testicular CYP19 mRNA was quantified using real time RT-PCR. Testicular aromatase activity was measured using the (3)H(2)0 assay and protein expression was evaluated using immunohistochemistry. In cases, serum testosterone and oestradiol were normal, but the testosterone/LH ratio was lower compared with controls (p < 0.05). Aromatase was localized in the Leydig, Sertoli and germ cells of all tissues, although stronger intensity was observed in LC. Aromatase mRNA and activity were not altered in cases and correlated positively with LC number (r = 0.516 and r = 0.369; p < 0.008). The intratesticular oestradiol/testosterone ratio was elevated (p = 0.005) in complete SCOS patients compared with controls. In conclusion, testicular aromatase seems to be normal in most subjects with impaired spermatogenesis. However, an altered intratesticular oestradiol/testosterone ratio in some patients with complete SCOS suggests that aromatase is increased, which might contribute to Leydig cell dysfunction.

  10. Subgrouping of patients with oral lichen planus according to cytochrome P450 enzyme phenotype and genotype

    DEFF Research Database (Denmark)

    Kragelund, Camilla; Jensen, Siri Beier; Hansen, Claus

    2014-01-01

    Objective. This study aimed to determine if the activity of the environmentally influenced cytochrome P450 enzyme CYP1A2, alone or in combination with CYP2D6*4 genotype, discriminates subgroups of oral lichen planus (OLP) according to lifestyle factors and clinical manifestations. Study Design. A...

  11. Tumor-specific expression of cytochrome P450 CYP1B1.

    Science.gov (United States)

    Murray, G I; Taylor, M C; McFadyen, M C; McKay, J A; Greenlee, W F; Burke, M D; Melvin, W T

    1997-07-15

    Cytochrome P450 CYP1B1 is a recently cloned dioxin-inducible form of the cytochrome P450 family of xenobiotic metabolizing enzymes. An antibody raised against a peptide specific for CYP1B1 was found to recognize CYP1B1 expressed in human lymphoblastoid cells but not to recognize other forms of cytochrome P450, particularly CYP1A1 and CYP1A2. Using this antibody, the cellular distribution and localization of CYP1B1 were investigated by immunohistochemistry in a range of malignant tumors and corresponding normal tissues. CYP1B1 was found to be expressed at a high frequency in a wide range of human cancers of different histogenetic types, including cancers of the breast, colon, lung, esophagus, skin, lymph node, brain, and testis. There was no detectable immunostaining for CYP1B1 in normal tissues. These results provide the basis for the development of novel methods of cancer diagnosis based on the identification of CYP1B1 in tumor cells and the development of anticancer drugs that are selectively activated in tumors by CYP1B1.

  12. Cytochrome P450-mediated metabolism of the synthetic cannabinoids UR-144 and XLR-11

    DEFF Research Database (Denmark)

    Nielsen, Line Marie; Holm, Niels Bjerre; Olsen, Lars

    2016-01-01

    In recent years, synthetic cannabinoids have emerged in the illicit drug market, in particular via the Internet, leading to abuse of these drugs. There is currently limited knowledge about the specific enzymes involved in the metabolism of these drugs. In this study, we investigated the cytochrome...... P450 (CYP) enzymes involved in the metabolism of the two synthetic cannabinoids (1-pentyl-1H-indol-3-yl)-(2,2,3,3-tetramethylcyclopropyl)methanone (UR-144) and [1-(5-fluoropentyl)-1H-indol-3-yl)](2,2,3,3-tetramethylcyclopropyl)methanone (XLR-11). This study extends previous studies by identifying...... the specific CYP enzymes involved in the metabolism of UR-144 and XLR-11 utilizing a panel of nine recombinant enzymes (CYP1A2, 2B6, 2C8, 2C9, 2C18, 2C19, 2D6, 3A4, and 2E1). This is followed by an investigation of the effect of specific inhibitors targeted against CYP1A2, 2B6, 2C9, 2C19, 2D6 and 3A4 in human...

  13. Effects of 6-paradol, an unsaturated ketone from gingers, on cytochrome P450-mediated drug metabolism.

    Science.gov (United States)

    Kim, Hyeong Jun; Kim, In Sook; Rehman, Shaheed Ur; Ha, Sang Keun; Nakamura, Katsunori; Yoo, Hye Hyun

    2017-02-20

    Paradols are unsaturated ketones produced by biotransformation of shogaols in gingers. Among them, 6-paradol has been investigated as a new drug candidate due to its anti-inflammatory, apoptotic, and neuroprotective activities. In this study, the inhibitory effects of 6-paradol on the activities of cytochrome P450 (CYP) enzymes were investigated with human liver microsomes and recombinant CYP isozymes. 6-Paradol showed concentration-dependent inhibitory effects on CYP1A2, CYP2B6, CYP2C8, CYP2C9, and CYP2C19 isozymes, with IC50 values ranging from 3.8 to 21.4µM in recombinant CYP isozymes. However, the inhibition was not potentiated following pre-incubation, indicating that 6-paradol is not a mechanism-based inhibitor. These results suggest that pharmacokinetic drug-drug interactions might occur with 6-paradol, which must be considered in the process of new drug development.

  14. Inhibitory effects on cytochrome p450 enzymes of pentamidine and its amidoxime pro-drug.

    Science.gov (United States)

    Bürenheide, Anja; Kunze, Thomas; Clement, Bernd

    2008-07-01

    Pentamidine is an antimicrobial drug, intravenously used in the treatment of trypanosomiasis, leishmaniasis or pneumocystis pneumonia. To elucidate potential drug interactions with pentamidine and N,N'-dihydroxypentamidine, respectively, the cytochrome P450 (CYP450) inhibitory properties of these compounds were determined. The study was performed in vitro by using human liver microsomes and marker substrates of several CYP450 isoenzymes. Marker activities were investigated by high-performance liquid chromatography in presence of known selective inhibitors or at different concentrations of pentamidine and N,N'-dihydroxypentamidine, respectively. No or only minor influence on CYP1A2, 2A6, 2C9, 2C19, 2D6, 2E1 and 3A4 marker activities could be observed, suggesting that neither of the tested substances would exert a significant effect on hepatic CYP450 isoenzymes responsible for the metabolism of co-administrated drugs in vivo. However, in vivo studies are needed before final conclusions can be drawn.

  15. Endothelial expression of human cytochrome P450 epoxygenases lowers blood pressure and attenuates hypertension-induced renal injury in mice

    Science.gov (United States)

    Lee, Craig R.; Imig, John D.; Edin, Matthew L.; Foley, Julie; DeGraff, Laura M.; Bradbury, J. Alyce; Graves, Joan P.; Lih, Fred B.; Clark, James; Myers, Page; Perrow, A. Ligon; Lepp, Adrienne N.; Kannon, M. Alison; Ronnekleiv, Oline K.; Alkayed, Nabil J.; Falck, John R.; Tomer, Kenneth B.; Zeldin, Darryl C.

    2010-01-01

    Renal cytochrome P450 (CYP)-derived epoxyeicosatrienoic acids (EETs) regulate sodium transport and blood pressure. Although endothelial CYP-derived EETs are potent vasodilators, their contribution to the regulation of blood pressure remains unclear. Consequently, we developed transgenic mice with endothelial expression of the human CYP2J2 and CYP2C8 epoxygenases to increase endothelial EET biosynthesis. Compared to wild-type littermate controls, an attenuated afferent arteriole constrictor response to endothelin-1 and enhanced dilator response to acetylcholine was observed in CYP2J2 and CYP2C8 transgenic mice. CYP2J2 and CYP2C8 transgenic mice demonstrated modestly, but not significantly, lower mean arterial pressure under basal conditions compared to wild-type controls. However, mean arterial pressure was significantly lower in both CYP2J2 and CYP2C8 transgenic mice during coadministration of N-nitro-l-arginine methyl ester and indomethacin. In a separate experiment, a high-salt diet and subcutaneous angiotensin II was administered over 4 wk. The angiotensin/high-salt-induced increase in systolic blood pressure, proteinuria, and glomerular injury was significantly attenuated in CYP2J2 and CYP2C8 transgenic mice compared to wild-type controls. Collectively, these data demonstrate that increased endothelial CYP epoxygenase expression attenuates afferent arteriolar constrictor reactivity and hypertension-induced increases in blood pressure and renal injury in mice. We conclude that endothelial CYP epoxygenase function contributes to the regulation of blood pressure.—Lee, C. R., Imig, J. D., Edin, M. E., Foley, J., DeGraff, L. M., Bradbury, J. A., Graves, J. P., Lih, F. B., Clark, J., Myers, P., Perrow, A. L., Lepp, A. N., Kannon, M. A., Ronnekleiv, O. K., Alkayed, N. J., Falck, J. R., Tomer, K. B., Zeldin, D. C. Endothelial expression of human cytochrome P450 epoxygenases lowers blood pressure and attenuates hypertension-induced renal injury in mice. PMID:20495177

  16. Effect of Yi Qi Fu Mai (YQFM) (Lyophilized) on the Activity of Hepatic CYP1 A2 and CYP3A in Rats%Cocktail法评价注射用益气复脉(冻干)对大鼠肝微粒体CYP1A2、CYP3A的诱导作用

    Institute of Scientific and Technical Information of China (English)

    胡冰; 岳洁皓; 段超慧; 叶正良; 周大铮; 李德坤; 马英丽

    2012-01-01

    Objective: To investigate the effect of Yi Qi Fu Mai Injection (YQFM) (Lyophilized) on the activity of cyto-chrome P450 (CYP1A2, CYP3A) in rats. Method: Healthy wistar rats raised ethically were pretreated with YOFM(Lo-phhilized) via the caudal vein once daily for consecutive seven days, and then hepatic microsomes were prepared. A cocktail selective substrates consisting of the phenacetin (PN,CYP1A2) and testosterone (TS,CYP3A) was incubated with rat livermicrosomes. Determined by HPLC method, the formation rates of acetaminophen and 6β-OH testosterone, the metabolites of the probe drugs were used as an indicator to estimate the activity of CYP1A2 and CYP3A. Result: The formation rates of acetaminophen were(18.04 ± 1.00) ,(43. 07 ±2.90) , (27. 6 ±4. 5) ng o ( mg protein)-1 min-1 ,The formation rates of 6β -OH testosterone were(15.79 ± 1.43 ) , (40. 86 ± 3. 32) , (32. 8 ± 3. 67 ) ng o ( mg protein) -1 o min-1. Conclusion; YQFM has an induced effect on the activity of CYP1A2 and CYP3A.%目的:研究注射用益气复脉(冻干)Yi Qi Fu Mai Injection( YQFM) (Lyophilized)对大鼠肝微粒体CYP1A2、CYP3A的诱导作用.方法:将wistar大鼠分为生理盐水对照组,苯巴比妥钠诱导组,YQFM组,连续给药7天后处死,制备肝微粒体.采用Cocktail法,将特异性探针底物非那西丁(CYP1A2)、睾酮(CYP3A)与肝微粒体共孵育,采用高效液相色谱测定孵育所得代谢产物对乙酰氨基酚和6β一羟基睾酮的生成速率,来评价YQFM对CYP1A2、CYP3A的诱导作用.结果:空白对照组、诱导组和YQFM组的对乙酰氨基酚的生成速率分别为(18.04±1.00)、(43.07±2.90)、(27.6±4.5) ng·(mg protein)-1·min-1,6β-羟基睾酮的生成速率分别为(15.79±1.43)、(40.86±3.32)、(32.8±3.67 )ng·(mg protein) -1·min -1.结论:YQFM对大鼠肝微粒体CYP1A2、CYP3A有诱导作用.

  17. Aspergillus niger metabolism of citrus furanocoumarin inhibitors of human cytochrome P450 3A4

    Science.gov (United States)

    Fungi metabolize polycyclic aromatic hydrocarbons by a number of detoxification processes, including the formation of sulfated and glycosidated conjugates. A class of aromatic compounds important to the citrus industry is the furanocoumarins in grapefruit, and their metabolism in humans is critical...

  18. Let-7b inhibits human cancer phenotype by targeting cytochrome P450 epoxygenase 2J2.

    Directory of Open Access Journals (Sweden)

    Fuqiong Chen

    Full Text Available BACKGROUND: MicroRNAs (miRNAs are small, noncoding RNA molecules of 20 to 22 nucleotides that regulate gene expression by binding to their 3' untranslated region (3'UTR. Increasing data implicate altered miRNA participation in the progress of cancer. We previously reported that CYP2J2 epoxygenase promotes human cancer phenotypes. But whether and how CYP2J2 is regulated by miRNA is not understood. METHODS AND RESULTS: Using bioinformatics analysis, we found potential target sites for miRNA let-7b in 3'UTR of human CYP2J2. Luciferase and western blot assays revealed that CYP2J2 was regulated by let-7b. In addition, let-7b decreased the enzymatic activity of endogenous CYP2J2. Furthermore, let-7b may diminish cell proliferation and promote cell apoptosis of tumor cells via posttranscriptional repression of CYP2J2. Tumor xenografts were induced in nude mice by subcutaneous injection of MDA-MB-435 cells. The let-7b expression vector, pSilencer-let-7b, was injected through tail vein every 3 weeks. Let-7b significantly inhibited the tumor phenotype by targeting CYP2J2. Moreover, quantitative real-time polymerase chain reaction and western blotting were used to determine the expression levels of let-7b and CYP2J2 protein from 18 matched lung squamous cell cancer and adjacent normal lung tissues; the expression level of CYP2J2 was inversely proportional to that of let-7b. CONCLUSIONS: Our results demonstrated that the decreased expression of let-7b could lead to the high expression of CYP2J2 protein in cancerous tissues. These findings suggest that miRNA let-7b reduces CYP2J2 expression, which may contribute to inhibiting tumor phenotypes.

  19. In vitro Study on Herb-drug Interactions of Zuojin Pills Based on Cytochrome P450%基于细胞色素P450的左金丸体外药物相互作用研究

    Institute of Scientific and Technical Information of China (English)

    龚睿林; 吕春明; 石美智; 郭澄; 韩永龙

    2016-01-01

    目的::探讨左金丸对人肝细胞色素P450CYP1A2/2C8/2C9/2C19/2D6/3A4亚型的体外抑制作用。方法:左金丸、黄连和吴茱萸的水提物分别与CYP1A2/2C8/2C9/2C19/2D6/3A4/3A4亚型的7种混合探针底物在人肝微粒体中共同孵育后,采用液相色谱-串联质谱法( LC-MS/MS)同时测定这7种代谢产物(对乙酰氨基酚/6α-羟基紫杉醇/4-羟基双氯芬酸/4-羟基美芬妥英/右啡烷/1-羟基咪达唑仑/6β-羟基睾酮)的浓度,计算其IC50值表示对该亚型的抑制程度。结果:在人肝微粒体体外孵育体系中,左金丸提取物对CYP2D6的IC50值为11.6μg·ml-1,对CYP1A2和CYP3A4的IC50值分别为77.4μg·ml-1和97.0μg·ml-1,对其他亚型的 IC50值从334μg · ml-1到690μg · ml-1;黄连提取物对 CYP2D6的 IC50值为5.8μg · ml-1,对CYP1A2和CYP3A4的IC50值分别为36.8μg·ml-1和59.2μg·ml-1,对其他亚型的IC50值从163μg·ml-1到476μg·ml-1;吴茱萸提取物对CYPs的 IC50值均大于107μg · ml-1。结论:左金丸在体外对人肝微粒体 CYP2D6活性有抑制作用,对CYP1A2和CYP3A4活性有弱的抑制作用,其君药黄连在该抑制作用中起到了主要作用,在联合用药时应注意左金丸与CYP2D6相关的药物相互作用。%Objective: To explore the in vitro inhibition effect of Zuojin pills on 6 cytochrome P450 isoenzymes ( CYP1A2, CYP2C8, CYP2C9, CYP2C19, CYP2D6 and CYP3A4) in human liver microsomes. Methods:The water extract of Zuojin pills, Cop-tidis Rhizoma and Euodiae Fructus was respectively incubated with human liver microsomes in the presence of seven probe substrates of CYP450 isoenzymes, and seven metabolites of cytochrome P450 probe substrate ( paracetamol/CYP1A2, 6α-hydroxypaclitaxel/CYP2C8, 4-hydroxydiclofenac/CYP2C9, 4-hydroxymephenytoin/CYP2C19, dextrorphan/CYP2D6, 6β-hydroxytestosterone/CYP3A4 and 1-hydroxymidazolam/CYP3A4) were simultaneously measured by LC-MS/MS, and the inhibitory effects were evaluated with IC50 value

  20. Effect of in vitro and in vivo treatment with mitomycin C on activities of CYP2D1/2, CYP2C11, and CYP1A2 in rat liver%丝裂霉素C在体外和体内对大鼠肝脏CYP2D1/2,CYP2C11和CYP1A2活性的影响

    Institute of Scientific and Technical Information of China (English)

    郝福荣; 严敏芬; 童顺高; 许立明; 金一尊

    2004-01-01

    Aim To evaluate the effect of in vitro and in vivo treatment with mitomycin C (MMC) on activities of CYP2D1/2, CYP2C11, and CYP1A2 in the liver of male rats. Methods Using HPLC to determine the activities of the three isoenzymes in rat liver microsomes by detecting the specific metabolites of their substrates after treatment with inducers in vivo or inhibitors in vitro. Results In vitro, MMC inhibited the activity of CYP2D1/2, CYP2C11, and CYP1A2 in dexamethasone-induced microsomes by (19±6)% (P<0.05), (85 ±10)% (P<0.01), and (36±6)% (P<0.05), respectively, and decreased the activity of CYP1A2 in/3-naphthoflavone-induced microsomes by (58 ± 6) % (P < 0. 01 ).Rats were injected intraperitoneally with 20% of the LD50 of MMC for 3 or 6 d. The treatment showed no significant effect on microsomal activities of CYP2D1/2, CYP2C11 or CYP1A2. Conclusion MMC can inhibit the activities of CYP2D1/2, CYP2C11, and CYP1A2 in rat liver microsomes in vitro, but it showed no significant effect on the activities of the three isoenzymes in vivo.%目的研究丝裂霉素C(MMC)在体外和体内对大鼠肝脏CYP2D1/2,CYP2C11和CYP1A2活性的影响.方法用诱导剂和抑制剂分别在体内和体外调节大鼠肝脏P450同工酶活性,并用HPLC检测3种同工酶各自底物的特定代谢产物,以计算同工酶活性.结果在体外,MMC可以使地塞米松诱导的大鼠肝脏微粒体CYP2D1/2,CYP2C11和CYP1A2活性分别抑制(19±6)%(P<0.05),(85±10)%(P<0.01)和(36±6)%(P<0.05),并使β-萘黄酮诱导的CYP1A2活性降低(58±6)%(P<0.01).在体内,以20%LDso的剂量连续3 d或6 d腹腔注射MMC对大鼠肝脏CYP2D1/2,CYP2C11和CYP1A2活性的影响无统计学差异.结论在体外MMC可以抑制大鼠肝微粒体CYP2D1/2,CYP2C11和CYP1A2的活性,但在体内对这3种细胞色素P450同工酶活性的影响无统计学差异.

  1. Human plasma concentrations of five cytochrome P450 probes extrapolated from pharmacokinetics in dogs and minipigs using physiologically based pharmacokinetic modeling.

    Science.gov (United States)

    Shida, Satomi; Yamazaki, Hiroshi

    2016-09-01

    The pharmacokinetics of cytochrome P450 probes in humans can be extrapolated from corresponding data in cynomolgus monkeys using simplified physiologically based pharmacokinetic (PBPK) modeling. In the current study, despite some species difference in drug clearances, this modeling methodology was adapted to estimate human plasma concentrations of P450 probes based on data from commonly used medium-sized experimental animals, namely dogs and minipigs. Using known species allometric scaling factors and in vitro metabolic clearance data, the observed plasma concentrations of slowly eliminated caffeine and warfarin and rapidly eliminated omeprazole, metoprolol and midazolam in two young dogs were scaled to human oral monitoring equivalents. Using the same approach, the previously reported pharmacokinetics of the five P450 probes in minipigs was also scaled to human monitoring equivalents. The human plasma concentration profiles of the five P450 probes estimated by the simplified human PBPK models based on observed/reported pharmacokinetics in dogs/minipigs were consistent with previously published pharmacokinetic data in humans. These results suggest that dogs and minipigs, in addition to monkeys, could be suitable models for humans during research into new drugs, especially when used in combination with simple PBPK models.

  2. quantitative assessment of the influence of cytochrome P450 1A2 gene polymorphism and colorectal cancer risk.

    Directory of Open Access Journals (Sweden)

    Yuan Zhao

    Full Text Available Cytochrome P450 1A2 (CYP1A2 encodes a member of the cytochrome P450 superfamily of enzymes, which play a central role in activating and detoxifying many carcinogens and endogenous compounds thought to be involved in the development of colorectal cancer (CRC. The CYP1A2*C (rs2069514 and CYP1A2*F (rs762551 polymorphism are two of the most commonly studied polymorphisms of the gene for their association with risk of CRC, but the results are conflicting. To derive a more precise estimation of the relationship between CYP1A2 and genetic risk of CRC, we performed a comprehensive meta-analysis which included 7088 cases and 7568 controls from 12 published case-control studies. In a combined analysis, the summary per-allele odds ratio for CRC was 0.91 (95% CI: 0.83-1.00, P = 0.04, and 0.91 (95% CI: 0.68-1.22, P = 0.53, for CYP1A2 *F and *C allele, respectively. In the subgroup analysis by ethnicity, significant associations were found in Asians for CYP1A2*F and CYP1A2*C, while no significant associations were detected among Caucasian populations. Similar results were also observed using dominant genetic model. Potential sources of heterogeneity were explored by subgroup analysis and meta-regression. No significant heterogeneity was detected in most of comparisons. This meta-analysis suggests that the CYP1A2 *F and *C polymorphism is a protective factor against CRC among Asians.

  3. Pharmacogenetics and olanzapine treatment: CYP1A2*1F and serotonergic polymorphisms influence therapeutic outcome.

    Science.gov (United States)

    Laika, B; Leucht, S; Heres, S; Schneider, H; Steimer, W

    2010-02-01

    Psychiatric pharmacotherapy with olanzapine is commonplace. We investigated the influence of CYP1A2*1F (-163A, rs762551) and serotonergic polymorphisms on olanzapine serum concentrations and clinical outcome in a naturalistic clinical setting. Included were 124 Caucasian psychiatric inpatients treated with olanzapine for at least 4 weeks with steady-state serum concentrations available for 73 patients. The CYP1A2*1F polymorphism was reported to affect the inducibility of CYP1A2. In our study population, CYP1A2*1F/*1F genotype alone resulted in a 22% reduction of dose-/body weight-normalized olanzapine serum concentrations compared to homo- and heterozygote carriers of CYP1A2*1A (both groups without inducers). This effect was independent of the well-known effect of inducing agents (here tobacco smoke and carbamazepine which led to on average 28% lower concentrations in CYP1A2*1A carriers and 26% lower concentrations in CYP1A2*1F/*1F carriers). Consistently, patients with the CYP1A2*1F/*1F genotype taking inducers had 22% lower concentrations compared to CYP1A2*1A carriers taking inducers. The influence of genotype alone remained significant after Bonferroni's post hoc test. Higher olanzapine concentrations were significantly correlated with better improvement of paranoid and depressive symptoms in patients with schizophrenic disorders (Spearman's r=0.5, P=0.026 and P=0.006, respectively). No relationship between serum concentrations and the side effects (DOTES) score was detected. However, patients with the 5-HTR2A intron 2 (rs7997012) AA genotype suffered from more pronounced side effects compared to carriers of the GA or GG genotype (P=0.018 and P=0.002). Short-term weight gain under olanzapine therapy was significantly lower for 5-HTR2C -759 T-allele carriers (P=0.011). Our data suggest that the CYP1A2*1F/*1F genotype exhibits a significant influence on olanzapine concentrations independent of other inducing factors. Thus, CYP1A2*1F genotyping may be useful for

  4. Differential expression of cytochrome P450 enzymes from the CYP2C subfamily in the human brain.

    Science.gov (United States)

    Booth Depaz, Iris M; Toselli, Francesca; Wilce, Peter A; Gillam, Elizabeth M J

    2015-03-01

    Cytochrome P450 enzymes from the CYP2C subfamily play a prominent role in the metabolic clearance of many drugs. CYP2C enzymes have also been implicated in the metabolism of arachidonic acid to vasoactive epoxyeicosatrienoic acids. CYP2C8, CYP2C9, and CYP2C19 are expressed in the adult liver at significant levels; however, the expression of CYP2C enzymes in extrahepatic tissues such as the brain is less well characterized. Form-specific antibodies to CYP2C9 and CYP2C19 were prepared by affinity purification of antibodies raised to unique peptides. CYP2C9 and CYP2C19 were located in microsomal fractions of all five human brain regions examined, namely the frontal cortex, hippocampus, basal ganglia, amygdala, and cerebellum. Both CYP2C9 and CYP2C19 were detected predominantly within the neuronal soma but with expression extending down axons and dendrites in certain regions. Finally, a comparison of cortex samples from alcoholics and age-matched controls suggested that CYP2C9 expression was increased in alcoholics.

  5. Three-dimensional modelling of human cytochrome P450 1A2 and its interaction with caffeine and MeIQ

    Science.gov (United States)

    Lozano, J. J.; López-de-Briñas, E.; Centeno, N. B.; Guigó, R.; Sanz, F.

    1997-07-01

    The three-dimensional modelling of proteins is a useful tool to fill the gap between the number of sequenced proteins and the number of experimentally known 3D structures. However, when the degree of homology between the protein and the available 3D templates is low, model building becomes a difficult task and the reliability of the results depends critically on the correctness of the sequence alignment. For this reason, we have undertaken the modelling of human cytochrome P450 1A2 starting by a careful analysis of several sequence alignment strategies (multiple sequence alignments and the TOPITS threading technique). The best results were obtained using TOPITS followed by a manual refinement to avoid unlikely gaps. Because TOPITS uses secondary structure predictions, several methods that are available for this purpose (Levin, Gibrat, DPM, NnPredict, PHD, SOPM and NNSP) have also been evaluated on cytochromes P450 with known 3D structures. More reliable predictions on α-helices have been obtained with PHD, which is the method implemented in TOPITS. Thus, a 3D model for human cytochrome P450 1A2 has been built using the known crystal coordinates of P450 BM3 as the template. The model was refined using molecular mechanics computations. The model obtained shows a consistent location of the substrate recognition segments previously postulated for the CYP2 family members. The interaction of caffeine and a carcinogenic aromatic amine (MeIQ), which are characteristic P450 1A2 substrates, has been investigated. The substrates were solvated taking into account their molecular electrostatic potential distributions. The docking of the solvated substrates in the active site of the model was explored with the AUTODOCK programme, followed by molecular mechanics optimisation of the most interesting complexes. Stable complexes were obtained that could explain the oxidation of the considered substrates by cytochrome P450 1A2 and could offer an insight into the role played by water

  6. Characterization of cardamonin metabolism by P450 in different species via HPLC-ESI-ion trap and UPLC-ESI-quadrupole mass spectrometry

    Institute of Scientific and Technical Information of China (English)

    Yuqi HE; Li YANG; Yong LIU; Jiang-wei ZHANG; Jun TANG; Juan SU; Yuan-yuan LI; Yan-liu LU; Chang-hong WANG; Ling YANG; Zheng-tao WANG

    2009-01-01

    Aim:To characterize the metabolism of cardamonin by the P450 enzymes in human and animal liver microsomes. Methods: Cardamonin was incubated with both human and animal liver microsomal incubation systems containing P450 reaction factors. High performance liquid chromatography coupled with ion trap mass spectrometry was used to identify the metabolites. Serial cardamonin dilutions were used to perform a kinetic study in human liver microsomes. Selective inhibitors of 7 of the major P450 isozymes were used to inhibit cardamonin hydroxylation to identify the isozymes involved in cardamonin metabolism. The cardamonin hydroxylation metabolic capacities of human and various other animals were investigated using the liver microsomal incubation system.Results: Two metabolites generated by the liver microsome system were detected and identified as hydroxylated cardamonin. The K_m and V_ (max) values for cardamonin hydroxylation were calculated as 32μmol/L and 35 pmotmol·~(-1)·mg~(-1), respectively.Fruafylline and clomethiazole significantly inhibited cardamonin hydroxylation. Guinea pigs showed the highest similarity to humans with respect to the metabolism of cardamonin.Conclusion: CYP 1A2 and 2E1 were identified as the P450 isozymes involved in the metabolism of cardamonin in human liver microsomes. Furthermore, our research suggests that guinea pigs could be used in the advanced pharmacokinetic studies of cardamonin in vivo.

  7. Effectsofplasmafrompatientswithacuteon chronicliverfailureonfunctionofcytochrome P450inimmortalizedhumanhepatocytes

    Institute of Scientific and Technical Information of China (English)

    Wei-Bo Du; Xiao-Ping Pan; Xiao-Peng Yu; Cheng-Bo Yu; Guo-Liang Lv; Yu Chen; Lan-Juan Li

    2010-01-01

    BACKGROUND: The bioartiifcial liver is anticipated to be a promising alternative choice for patients with liver failure. Toxic substances which accumulate in the patients' plasma exert deleterious effects on hepatocytes in the bioreactor, and potentially reduce the efifcacy of bioartiifcial liver devices. This study was designed to investigate the effects of plasma from patients with acute on chronic liver failure (AoCLF) on immortalized human hepatocytes in terms of cytochrome P450 gene expression, drug metabolism activity and detoxiifcation capability. METHODS: Immortalized human hepatocytes (HepLi-2 cells) were cultured in medium containing fetal calf serum or human plasma from three patients with AoCLF. The cytochrome P450 (CYP3A5, CYP2E1, CYP3A4) expression, drug metabolism activity and detoxiifcation capability of HepLi-2 cells were assessed by RT-PCR, lidocaine clearance and ammonia elimination assay. RESULTS: After incubation in medium containing AoCLF plasma for 24 hours, the cytochrome P450 mRNA expression of HepLi-2 cells was not signiifcantly decreased compared with control culture. Ammonia elimination and lidocaine clearance assay showed that the ability of ammonia removal and drug metabolism remained stable. CONCLUSIONS: Immortalized human hepatocytes can be exposed to AoCLF plasma for at least 24 hours with no signiifcant reduction in the function of cytochrome P450. HepLi-2 cells appear to be effective in metabolism and detoxiifcation and can be potentially used in the development of bioartiifcial liver.

  8. Altered heme catabolism by heme oxygenase-1 caused by mutations in human NADPH cytochrome P450 reductase

    Energy Technology Data Exchange (ETDEWEB)

    Pandey, Amit V., E-mail: amit@pandeylab.org [Pediatric Endocrinology, Diabetology and Metabolism, Department of Clinical Research, University of Bern, Tiefenaustrasse 120c, CH-3004 Bern (Switzerland); Flueck, Christa E.; Mullis, Primus E. [Pediatric Endocrinology, Diabetology and Metabolism, Department of Clinical Research, University of Bern, Tiefenaustrasse 120c, CH-3004 Bern (Switzerland)

    2010-09-24

    Research highlights: {yields} Mutations in POR identified from patients lead to reduced HO-1 activities. {yields} POR mutation Y181D affecting FMN binding results in total loss of HO-1 activity. {yields} POR mutations A287P, C569Y and V608F, lost 50-70% activity. {yields} Mutations in FAD binding domain, R457H, Y459H and V492E lost all HO-1 activity. {yields} POR polymorphisms P228L, R316W, G413S, A503V and G504R have normal activity. -- Abstract: Human heme oxygenase-1 (HO-1) carries out heme catabolism supported by electrons supplied from the NADPH through NADPH P450 reductase (POR, CPR). Previously we have shown that mutations in human POR cause a rare form of congenital adrenal hyperplasia. In this study, we have evaluated the effects of mutations in POR on HO-1 activity. We used purified preparations of wild type and mutant human POR and in vitro reconstitution with purified HO-1 to measure heme degradation in a coupled assay using biliverdin reductase. Here we show that mutations in POR found in patients may reduce HO-1 activity, potentially influencing heme catabolism in individuals carrying mutant POR alleles. POR mutants Y181D, A457H, Y459H, V492E and R616X had total loss of HO-1 activity, while POR mutations A287P, C569Y and V608F lost 50-70% activity. The POR variants P228L, R316W and G413S, A503V and G504R identified as polymorphs had close to WT activity. Loss of HO-1 activity may result in increased oxidative neurotoxicity, anemia, growth retardation and iron deposition. Further examination of patients affected with POR deficiency will be required to assess the metabolic effects of reduced HO-1 activity in affected individuals.

  9. Identification of the human P450 enzymes involved in the in vitro metabolism of the synthetic steroidal hormones Org 4060 and Org 30659

    NARCIS (Netherlands)

    Verhoeven, CHJ; Van Munster, TTM; Groothuis, GMM; Vos, RME; Rietjens, IMCM

    2002-01-01

    1. The type of human P450 enzymes involved in the in vitro metabolism of Org 4060 and Org 30659, two synthetic steroidal hormones currently under clinical development by NV Organon for use in oral contraceptive and hormone replacement therapy, was investigated. 2. Both steroids were mainly hydroxyla

  10. 超高效液相色谱法检测6种探针底物代谢产物并评价人细胞色素P450同工酶活性%Simultaneous Determination of 6 Kinds of Probe Substrate Metabolites and Rapid Evaluation of Human Cytochrome P450 Isoenzyme Activity by UPLC-MS/MS

    Institute of Scientific and Technical Information of China (English)

    陆苑; 谢玉敏; 潘洁; 黄勇; 王永林

    2015-01-01

    目的:建立同时测定非那西丁(CYP1A2)、氯唑沙宗(CYP2E1)、甲苯磺丁脲(CYP2C9)、奥美拉唑(CYP2C19)、睾酮和咪达唑仑(CYP3A4)6种探针底物代谢产物的Cocktail体外方法,评价药物对人肝微粒体CYP450同工酶活性的影响。方法:人肝微粒体与6种探针底物在还原系统NADPH的作用下,37℃共同孵育;以蛋白沉淀法处理样品,采用超高效液相色谱系统( UPLC-MS/MS),建立Cocktail混合探针,对药物的6种代谢物进行定量分析,并分析药物对人肝微粒体CYP450同工酶活性的影响。结果:6种探针底物物代谢产物乙酰氨基酚(0.26~8.35μmol/L)、6-羟基氯唑沙宗(3.02~96.63μmol/L)、5-羟基奥美拉唑(0.10~3.09μmol/L)、羟基甲苯磺丁脲(0.15~4.88μmol/L )、6β-羟基睾酮(3.67~117.37μmol/L )和α-羟基咪达唑仑(1.64~52.37μmol/L)线性关系良好,各成分相关系数( R2)>0.996,准确度为95.96%~103.10%,日内和日间精密度RSD(%)<15%,提取回收率、基质效应RSD(%)<11%,稳定性好。结论:UPLC-MS/MS准确、灵敏度高,可作为研究受试药物对CYP450酶影响及相关研究的分析测定方法。%Objective:To establish cocktail method for simultaneous determination of 6 kinds of probe substrate metabolites:phenacetin and chlorzoxazone ( CYP1 A2 ), CYP2 E1 , tolbutamide (CYP2C9),omeprazole(CYP2C19),testosterone and midazolam(CYP3A4)in vitro,evaluating the effects of medicine on human liver microsomesˊCYP450 isozyme activity. Methods:Under the func-tion of NADPH,human liver microsomes interacted with 6 kinds of probe substrates at 37℃. Using protein precipitation to handle the samples. Adopting UPLC/MS/MS and establishing Cocktail mixed probes to carry out quantitative analysis on the 6 kinds of metabolites,analyzing the effect of medicine on human liver microsomesˊCYP450 isozyme activity. Results:A good

  11. Cytochrome P450-mediated metabolism of tumour promoters modifies the inhibition of intercellular communication: a modified assay for tumour promotion

    DEFF Research Database (Denmark)

    Vang, Ole; Wallin, H.; Doehmer, J.;

    1993-01-01

    The role of metabolism of tumour promoters on the inhibition of intercellular communication was investigated in a modified V79 metabolic cooperation system. V79 cells, which stably express different rat cytochrome P450 enzymes (CYP1A1, CYP1A2 or CYP2B1), were used in the metabolic cooperation ass...

  12. Reconstitution of the interplay between cytochrome P450 and human glutathione S-transferases in clozapine metabolism in yeast.

    Science.gov (United States)

    Vredenburg, Galvin; Vassell, Kadene P T; Commandeur, Jan N M; Vermeulen, Nico P E; Vos, J Chris

    2013-10-01

    Clozapine, an often-prescribed antipsychotic drug, is implicated in severe adverse drug reactions (ADRs). Formation of reactive intermediates by cytochrome P450s (CYPs) has been proposed as a possible explanation for these ADRs. Moreover, a protective role for human glutathione S-transferases (hGSTs) was recently shown using purified enzymes. We investigated the interplay between CYP bioactivation and GST detoxification in a reconstituted cellular context using recombinant yeast expressing a bacterial CYP BM3 mutant (M11), mimicking the drug-metabolizing potential of human CYPs, combined with hGSTA1-1, M1-1 or P1-1. Clozapine and the N-desmethylclozapine metabolite caused comparable growth inhibition and reactive oxygen species (ROS) formation, whereas the clozapine-N-oxide metabolite was clearly less toxic. Clozapine metabolism by BM3 M11 and the hGSTs in yeast was confirmed by identification of stable clozapine metabolites and hGST isoform-specific glutathione-conjugates. Oxidative metabolism of clozapine by BM3 M11 increased ROS formation and growth inhibition. Co-expression of hGSTP1-1 protected yeast from BM3 M11 induced growth inhibition in presence of clozapine, whereas similar expression levels of hGSTA1-1 and hGSTM1-1 did not. ROS formation was not lowered by hGSTP1-1 co-expression and was unrelated to mitochondrial electron transport chain (mETC) activity. We present a novel cellular model to study the effect of CYP and GST interplay in drug toxicity.

  13. Expression and characterization of truncated human heme oxygenase (hHO-1) and a fusion protein of hHO-1 with human cytochrome P450 reductase.

    Science.gov (United States)

    Wilks, A; Black, S M; Miller, W L; Ortiz de Montellano, P R

    1995-04-04

    A human heme oxygenase (hHO-1) gene without the sequence coding for the last 23 amino acids has been expressed in Escherichia coli behind the pho A promoter. The truncated enzyme is obtained in high yields as a soluble, catalytically-active protein, making it available for the first time for detailed mechanistic studies. The purified, truncated hHO-1/heme complex is spectroscopically indistinguishable from that of the rat enzyme and converts heme to biliverdin when reconstituted with rat liver cytochrome P450 reductase. A self-sufficient heme oxygenase system has been obtained by fusing the truncated hHO-1 gene to the gene for human cytochrome P450 reductase without the sequence coding for the 20 amino acid membrane binding domain. Expression of the fusion protein in pCWori+ yields a protein that only requires NADPH for catalytic turnover. The failure of exogenous cytochrome P450 reductase to stimulate turnover and the insensitivity of the catalytic rate toward changes in ionic strength establish that electrons are transferred intramolecularly between the reductase and heme oxygenase domains of the fusion protein. The Vmax for the fusion protein is 2.5 times higher than that for the reconstituted system. Therefore, either the covalent tether does not interfere with normal docking and electron transfer between the flavin and heme domains or alternative but equally efficient electron transfer pathways are available that do not require specific docking.

  14. Computational Identification of the Paralogs and Orthologs of Human Cytochrome P450 Superfamily and the Implication in Drug Discovery

    Directory of Open Access Journals (Sweden)

    Shu-Ting Pan

    2016-06-01

    Full Text Available The human cytochrome P450 (CYP superfamily consisting of 57 functional genes is the most important group of Phase I drug metabolizing enzymes that oxidize a large number of xenobiotics and endogenous compounds, including therapeutic drugs and environmental toxicants. The CYP superfamily has been shown to expand itself through gene duplication, and some of them become pseudogenes due to gene mutations. Orthologs and paralogs are homologous genes resulting from speciation or duplication, respectively. To explore the evolutionary and functional relationships of human CYPs, we conducted this bioinformatic study to identify their corresponding paralogs, homologs, and orthologs. The functional implications and implications in drug discovery and evolutionary biology were then discussed. GeneCards and Ensembl were used to identify the paralogs of human CYPs. We have used a panel of online databases to identify the orthologs of human CYP genes: NCBI, Ensembl Compara, GeneCards, OMA (“Orthologous MAtrix” Browser, PATHER, TreeFam, EggNOG, and Roundup. The results show that each human CYP has various numbers of paralogs and orthologs using GeneCards and Ensembl. For example, the paralogs of CYP2A6 include CYP2A7, 2A13, 2B6, 2C8, 2C9, 2C18, 2C19, 2D6, 2E1, 2F1, 2J2, 2R1, 2S1, 2U1, and 2W1; CYP11A1 has 6 paralogs including CYP11B1, 11B2, 24A1, 27A1, 27B1, and 27C1; CYP51A1 has only three paralogs: CYP26A1, 26B1, and 26C1; while CYP20A1 has no paralog. The majority of human CYPs are well conserved from plants, amphibians, fishes, or mammals to humans due to their important functions in physiology and xenobiotic disposition. The data from different approaches are also cross-validated and validated when experimental data are available. These findings facilitate our understanding of the evolutionary relationships and functional implications of the human CYP superfamily in drug discovery.

  15. Expressed and Purified Recombinant Human Cytochrome P450 3A4%重组细胞色素酶P450 3A4表达和鉴定

    Institute of Scientific and Technical Information of China (English)

    柳艾姣; 石磊; 方方; 赵树进

    2012-01-01

    Cytochrome P450 is an important enzyme for metabolism of endogenous substances and exogenous substances, and plays a decisive role in drug treatment, drug development and understanding the metabolism of potential toxic substances and carcinogenic substances. In order to construct the expression vector of cytochrome P450 3A4,expressed and purified CYP3A4 protein in Escherichia coli,reverse transcription-polymerase chain reaction was used to obtain CYP3A4 Cdna from human liver total RNA,and then inserted directly into the Pmd (R) 20-T Vector. The correct sequencing was modified with N-terminal and C-terminal that have been conducive to the expression. After double digestion the CYP3A4 gene was inserted into the expression vector Pet-28a-c ( + ) vectors and transformed into E. coli BL21 ( DE3 ) to express. CYP3A4 mutation subtype of CYP3A4 * 19 was obtained by site-directed mutagenesis. Four factors and two levels of orthogonal experiment designed by SPSS13. 0 to optimize four factors of a-ALA (0.5 mmol/L and 1 mmol/L) ,IPTG (0.5 mmol/L and 1 mmol/L) .kanamycin (50 μg/Ml and 100 μg/Ml) concentration and bacteria inoculation density (inoculation 1% and inoculated with 2%) for portent expression. The results were analyzed using SPSS13. 0 to select a good combination of large-scale induced expression. CYP3A4 protein was induced by IPTG,and verified by Western blot. Membrane protein concentration is around 65 μg/Ml. The level of a-ALA, antibiotics ( kanamycin) , IPTG, inoculation density on the level of expression of membrane proteins was not statistically significant. Expression of membrane proteins was verified by Western blot for recombinant CYP3A4 protein. The cloning of cytochrome P450 3A4 protein was obtained that laid the foundation for drug interaction experiments in vitro.%细胞色素酶P450是代谢内源性物质和外源性物质的重要的酶,在药物治疗和药物开发领域以及了解潜在的毒性物质和致癌性物质的代谢机制起决定

  16. Artificial neural network cascade identifies multi-P450 inhibitors in natural compounds

    Directory of Open Access Journals (Sweden)

    Zhangming Li

    2015-12-01

    Full Text Available Substantial evidence has shown that most exogenous substances are metabolized by multiple cytochrome P450 (P450 enzymes instead of by merely one P450 isoform. Thus, multi-P450 inhibition leads to greater drug-drug interaction risk than specific P450 inhibition. Herein, we innovatively established an artificial neural network cascade (NNC model composed of 23 cascaded networks in a ladder-like framework to identify potential multi-P450 inhibitors among natural compounds by integrating 12 molecular descriptors into a P450 inhibition score (PIS. Experimental data reporting in vitro inhibition of five P450 isoforms (CYP1A2, CYP2C9, CYP2C19, CYP2D6, and CYP3A4 were obtained for 8,148 compounds from the Cytochrome P450 Inhibitors Database (CPID. The results indicate significant positive correlation between the PIS values and the number of inhibited P450 isoforms (Spearman’s ρ = 0.684, p < 0.0001. Thus, a higher PIS indicates a greater possibility for a chemical to inhibit the enzyme activity of at least three P450 isoforms. Ten-fold cross-validation of the NNC model suggested an accuracy of 78.7% for identifying whether a compound is a multi-P450 inhibitor or not. Using our NNC model, 22.2% of the approximately 160,000 natural compounds in TCM Database@Taiwan were identified as potential multi-P450 inhibitors. Furthermore, chemical similarity calculations suggested that the prevailing parent structures of natural multi-P450 inhibitors were alkaloids. Our findings show that dissection of chemical structure contributes to confident identification of natural multi-P450 inhibitors and provides a feasible method for virtually evaluating multi-P450 inhibition risk for a known structure.

  17. Cloning of cytochrome P-450 2C9 cDNA from human liver and its expression in CHL cells

    Institute of Scientific and Technical Information of China (English)

    Ge-Jian Zhu; Ying-Nian Yu; Xin Li; Yu-Li Qian

    2002-01-01

    AIM: Using bacterial, yeast, or mammalian cell expressing a human drug metabolism enzyme would seem good way to study drug metabolism-related problems. Human cytochrome P-450 2C9 ( CYP2 C9) is a polymorphic enzyme responsible for the metabolism of a large number of clinically important drugs. It ranks among the most important drug metabolizing enzymes in humans. In order to provide a sufficient amount of the enzyme for drug metabolic research, the CYP2 C9 eDNA was cloned and expressed stably in CHL cellsMETHODS: After extraction of total RNA from human livertissue, the human CYP2C9 eDNA was amplified withreverse transcription-polymerase chain reaction (RT-PCR),and cloned into cloning vector pGEM-T. The cDNA fragmentwas identified by DNA sequencing and subcloned into amammalian expression vector pREP9. A transgenic cell linewas established by transfecting the recombinant vector ofpREP9-CYP2C9 into CHL cells. The enzyme activity ofCYP2C9 catalyzing oxidation of tolbutamide to hydroxytolbutamide in S9 fraction of the cell was determined by highperformance liquid chromatography(HPLC).RESULTS: The amino acid sequence predicted from theeDNA segment was identical to that of CYP2 C9 * 1, the wildtype CYP2 C9. However, there were two base differences, i.e. 21T > C, 1146C > T, but the encoding amino acidsequence was the same, L7, P382. The S9 fraction of theestablished cell line metabolizes tolbutamide to hydroxytolbutamide; tolbutamide hydroxylass activity was found to be0.465 ± 0.109 μmol@ min-1 . g1 S9 protein or 8.62 ± 2.02 mol@ min 1 ~mol-1 CYP, but was undetectable in parental CHL cell.CONCLUSION: The cDNA of human CYP2C9 was successfullycloned and a cell line of CHL- CYP2C9, efficiently expressingthe protein of CYP2C9, was established.

  18. In Vitro and in Vivo Inhibitory Effects of Glycyrrhetinic Acid in Mice and Human Cytochrome P450 3A4

    Directory of Open Access Journals (Sweden)

    Qiao-Li Lv

    2015-12-01

    Full Text Available Glycyrrhetinic acid (GA has been used clinically in the treatment of patients with chronic hepatitis. This study evaluated the effect of GA on the activity of five P450(CYP450 cytochrome enzymes: CYP2A6, CYP2C9, CYP2C19, CYP2D6, and CYP3A4, in human liver microsomes (HLMs and recombinant cDNA-expressed enzyme systems using a HPLC-MS/MS CYP-specific probe substrate assay. With midazolam as the probe substrate, GA greatly decreased CYP3A4 activity with IC50 values of 8.195 μM in HLMs and 7.498 μM in the recombinant cDNA-expressed CYP3A4 enzyme system, respectively. It significantly decreased CYP3A4 activity in a dose- but not time-dependent manner. Results from Lineweaver–Burk plots showed that GA could inhibit CYP3A4 activity competitively, with a Ki value of 1.57 μM in HLMs. Moreover, CYP2C9 and CYP2C19 could also be inhibited significantly by GA with IC50 of 42.89 and 40.26 μM in HLMs, respectively. Other CYP450 isoforms were not markedly affected by GA. The inhibition was also confirmed by an in vivo study of mice. In addition, it was observed that mRNA expressions of the Cyps2c and 3a family decreased significantly in the livers of mice treated with GA. In conclusion, this study indicates that GA may exert herb-drug interactions by competitively inhibiting CYP3A4.

  19. In vitro metabolism of fipronil by human and rat cytochrome P450 and its interactions with testosterone and diazepam.

    Science.gov (United States)

    Tang, Jun; Amin Usmani, K; Hodgson, Ernest; Rose, Randy L

    2004-04-15

    Fipronil (5-amino-1-[2,6-dichloro-4-(trifluoromethyl)phenyl]-4-[(trifluoromethyl)sulfinyl]-1H-pyrazole-3-carbonitrile) is a highly active, broad spectrum insecticide from the phenyl pyrazole family, which targets the gamma-amino butyric acid (GABA) receptor. Although fipronil is presently widely used as an insecticide and acaricide, little information is available with respect to its metabolic fate and disposition in mammals. This study was designed to investigate the in vitro human metabolism of fipronil and to examine possible metabolic interactions that fipronil may have with other substrates. Fipronil was incubated with human liver microsomes (HLM) and several recombinant cytochrome P450 (CYP) isoforms obtained from BD Biosciences. HPLC was used for metabolite identification and quantification. Fipronil sulfone was the predominant metabolite via CYP oxidation. The K(m) and V(max) values for human liver microsomes are 27.2 microM and 0.11 nmol/mg proteinmin, respectively; for rat liver microsomes (RLM) the K(m) and V(max) are 19.9 microM and 0.39 nmol/mg proteinmin, respectively. CYP3A4 is the major isoform responsible for fipronil oxidation in humans while CYP2C19 is considerably less active. Other human CYP isoforms have minimal or no activity toward fipronil. Co-expression of cytochrome b(5) (b(5)) is essential for CYP3A4 to manifest high activity toward fipronil. Ketoconazole, a specific inhibitor of CYP3A4, inhibits 78% of the HLM activity toward fipronil at a concentration of 2 microM. Oxidative activity toward fipronil in 19 single-donor HLMs correlated well with their ability to oxidize testosterone. The interactions of fipronil and other CYP3A4 substrates, such as testosterone and diazepam, were also investigated. Fipronil metabolism was activated by testosterone in HLM but not in CYP3A4 Supersomes. Testosterone 6beta-hydroxylation in HLM was inhibited by fipronil. Fipronil inhibited diazepam demethylation but had little effect on diazepam hydroxylation

  20. Overexpression of pregnane X and glucocorticoid receptors and the regulation of cytochrome P450 in human epileptic brain endothelial cells.

    Science.gov (United States)

    Ghosh, Chaitali; Hossain, Mohammed; Solanki, Jesal; Najm, Imad M; Marchi, Nicola; Janigro, Damir

    2017-04-01

    Recent evidence suggests a metabolic contribution of cytochrome P450 enzymes (CYPs) to the drug-resistant phenotype in human epilepsy. However, the upstream molecular regulators of CYP in the epileptic brain remain understudied. We therefore investigated the expression and function of pregnane xenobiotic (PXR) and glucocorticoid (GR) nuclear receptors in endothelial cells established from post-epilepsy surgery brain samples. PXR/GR localization was evaluated by immunohistochemistry in specimens from subjects who underwent temporal lobe resections to relieve drug-resistant seizures. We used primary cultures of endothelial cells obtained from epileptic brain tissues (EPI-ECs; n = 8), commercially available human brain microvascular endothelial cells (HBMECs; n = 8), and human hepatocytes (n = 3). PXR/GR messenger RNA (mRNA) levels in brain ECs was initially determined by complementary DNA (cDNA) microarrays. The expression of PXR/GR proteins was quantified by Western blot. PXR and GR silencing was performed in EPI-ECs (n = 4), and the impact on downstream CYP expression was determined. PXR/GR expression was detected by immunofluorescence in ECs and neurons in the human temporal lobe samples analyzed. Elevated mRNA and protein levels of PXR and GR were found in EPI-ECs versus control HBMECs. Hepatocytes, used as a positive control, displayed the highest levels of PXR/GR expression. We confirmed expression of PXR/GR in cytoplasmic-nuclear subcellular fractions, with a significant increase of PXR/GR in EPI-ECs versus controls. CYP3A4, CYP2C9, and CYP2E1 were overexpressed in EPI-ECs versus control, whereas CYP2D6 and CYP2C19 were downregulated or absent in EPI-ECs. GR silencing in EPI-ECs led to decreased CYP3A4, CYP2C9, and PXR expression. PXR silencing in EPI-ECs resulted in the specific downregulation of CYP3A4 expression. Our results indicate increased PXR and GR in primary ECs derived from human epileptic brains. PXR or GR may be responsible for a local drug brain

  1. Pilot Study on Genetic Polymorphisms CYP1A2*1F on Asthma Patients and Nonasthma in Indonesia

    Directory of Open Access Journals (Sweden)

    Doddy de Queljoe

    2015-03-01

    Full Text Available Genetic polymorphisms of CYP1A2 is related to the theophylline metabolism that may affect drug levels in the blood, which can also affect incidence of adverse drug reaction (ADR and clinical outcomes of asthma therapy. The frequency of CYP1A2 polymorphism is known to vary among ethnic. Allegedly the Indonesian population has high frequency of gene variants of CYP1A2*1F. This study aims to determine the profile of CYP1A2*1F gene polymorphism in a sample of nonasthma and asthma in Indonesia with other populations based on the literature. Data were taken on January–June 2014. Blood samples were obtained from 29 nonasthma samples and 16 patients with asthma. After extraction of genomic DNA, CYP1A2*1F gene polymorphisms determined by PCR-RFLP. The results of this study indicate that the CYP1A2*1F gene polymorphism in nonasthma samples was 10.35% (3/29 for C/C, 37.93% (11/29 for the C/A, and 51.72% (15/29 for A/A. The asthmatics genotype have a frequency distribution of C/A genotype of 81.25% (13/16 and A/A of 18.75% (3/16. There was no significant difference (p=0.276 allele frequencies between samples of nonasthma and asthma patients. The frequency of CYP1A2*1F gene in Indonesian population is higher than the population of Egypt, Japan, and UK, but lower compared to Malaysia. It can be concluded that there is no difference in frequency.

  2. Coffee consumption and CYP1A2 genotype in relation to bone mineral density of the proximal femur in elderly men and women: a cohort study

    Directory of Open Access Journals (Sweden)

    Lind Lars

    2010-02-01

    Full Text Available Abstract Background Drinking coffee has been linked to reduced calcium conservation, but it is less clear whether it leads to sustained bone mineral loss and if individual predisposition for caffeine metabolism might be important in this context. Therefore, the relation between consumption of coffee and bone mineral density (BMD at the proximal femur in men and women was studied, taking into account, for the first time, genotypes for cytochrome P450 1A2 (CYP1A2 associated with metabolism of caffeine. Methods Dietary intakes of 359 men and 358 women (aged 72 years, participants of the Prospective Investigation of the Vasculature in Uppsala Seniors (PIVUS, were assessed by a 7-day food diary. Two years later, BMD for total proximal femur, femoral neck and trochanteric regions of the proximal femur were measured by Dual-energy X-ray absorptiometry (DXA. Genotypes of CYP1A2 were determined. Adjusted means of BMD for each category of coffee consumption were calculated. Results Men consuming 4 cups of coffee or more per day had 4% lower BMD at the proximal femur (p = 0.04 compared with low or non-consumers of coffee. This difference was not observed in women. In high consumers of coffee, those with rapid metabolism of caffeine (C/C genotype had lower BMD at the femoral neck (p = 0.01 and at the trochanter (p = 0.03 than slow metabolizers (T/T and C/T genotypes. Calcium intake did not modify the relation between coffee and BMD. Conclusion High consumption of coffee seems to contribute to a reduction in BMD of the proximal femur in elderly men, but not in women. BMD was lower in high consumers of coffee with rapid metabolism of caffeine, suggesting that rapid metabolizers of caffeine may constitute a risk group for bone loss induced by coffee.

  3. Impact of Tetrahydropalmatine on the Pharmacokinetics of Probe Drugs for CYP1A2, 2D6 and 3A Isoenzymes in Beagle Dogs.

    Science.gov (United States)

    Zhao, Yong; Liang, Aihua; Zhang, Yushi; Li, Chunying; Yi, Yan; Nilsen, Odd Georg

    2016-06-01

    Tetrahydropalmatine (Tet) exhibit multiple pharmacological activities and is used frequently by clinical practitioners. In this study, we evaluate the in vivo effects of single and repeated oral Tet administrations on CYP1A2, 2D6 and 3A activities in six beagle dogs in a randomized, controlled, open-label, crossover study. A cocktail approach, with dosages of the probe drugs caffeine (3.0 mg/kg), metoprolol (2.33 mg/kg) and midazolam (0.45 mg/kg), was used to measure cytochrome P450 (CYP) metabolic activities. The cocktail was administered orally as a single dose (12 mg/kg) 1 day prior to and 4 days after repeated oral Tet administrations (12 mg/kg three times daily). The probe drugs and their metabolites in plasma were quantified simultaneously by a validated HPLC technique, and non-compartmental parameters were used to evaluate metabolic variables for assessment of CYP inhibition or induction. Tet had no or minor impact on the pharmacokinetics and metabolism of the probe drugs caffeine and metoprolol, CYP1A2 and CYP2D6 substrates, respectively. However, Tet increased AUC0-24 h and decreased AUCratio(0-24 h) (1-hydroxymidazolam/midazolam ratio) for midazolam statistically significant, both in single or multiple dosing of Tet, with up to 39 or 57% increase for AUC0-24 h and 29% or 22 decrease for AUCratio(0-24 h), respectively, in line with previous in vitro findings for its CYP3A4 inhibition. The extensive use of Tet and herbal medicines containing Tet makes Tet a candidate for further evaluation of CYP3A-mediated herb-drug interactions. Copyright © 2016 John Wiley & Sons, Ltd.

  4. Quantitative Atlas of Cytochrome P450, UDP-Glucuronosyltransferase, and Transporter Proteins in Jejunum of Morbidly Obese Subjects.

    Science.gov (United States)

    Miyauchi, Eisuke; Tachikawa, Masanori; Declèves, Xavier; Uchida, Yasuo; Bouillot, Jean-Luc; Poitou, Christine; Oppert, Jean-Michel; Mouly, Stéphane; Bergmann, Jean-François; Terasaki, Tetsuya; Scherrmann, Jean-Michel; Lloret-Linares, Célia

    2016-08-01

    Protein expression levels of drug-metabolizing enzymes and transporters in human jejunal tissues excised from morbidly obese subjects during gastric bypass surgery were evaluated using quantitative targeted absolute proteomics. Protein expression levels of 15 cytochrome P450 (CYP) enzymes, 10 UDP-glucuronosyltransferase (UGT) enzymes, and NADPH-P450 reductase (P450R) in microsomal fractions from 28 subjects and 49 transporters in plasma membrane fractions from 24 of the same subjects were determined using liquid chromatography-tandem mass spectrometry. Based on average values, UGT1A1, UGT2B15, UGT2B17, SGLT1, and GLUT2 exhibited high expression levels (over 10 fmol/μg protein), though UGT2B15 expression was detected at a high level in only one subject. CYP2C9, CYP2D6, CYP3A5, UGT1A6, P450R, ABCG2, GLUT5, PEPT1, MCT1, 4F2 cell-surface antigen heavy chain (4F2hc), LAT2, OSTα, and OSTβ showed intermediate levels (1-10 fmol/μg protein), and CYP1A1, CYP1A2, CYP1B1, CYP2C18, CYP2C19, CYP2J2, CYP3A7, CYP4A11, CYP51A1, UGT1A3, UGT1A4, UGT1A8, UGT2B4, ABCC1, ABCC4, ABCC5, ABCC6, ABCG8, TAUT, OATP2A1, OATP2B1, OATP3A1, OATP4A1, OCTN1, CNT2, PCFT, MCT4, GLUT4, and SLC22A18 showed low levels (less than 1 fmol/μg protein). The greatest interindividual difference (364-fold) was detected for UGT2B17. However, differences in expression levels of other quantified UGTs (except UGT2B15 and UGT2B17), CYPs (except CYP1A1 and CYP3A5), and P450R, and all quantified transporters, were within 10-fold. Expression levels of CYP1A2 and GLUT4 were significantly correlated with body-mass index. The levels of 4F2hc showed significant gender differences. Smokers showed increased levels of UGT1A1 and UGT1A3. These findings provide a basis for understanding the changes in molecular mechanisms of jejunal metabolism and transport, as well as their interindividual variability, in morbidly obese patients.

  5. Associations between polymorphisms in the AHR and CYP1A1-CYP1A2 gene regions and habitual caffeine consumption.

    Science.gov (United States)

    Josse, Andrea R; Da Costa, Laura A; Campos, Hannia; El-Sohemy, Ahmed

    2012-09-01

    Recent genome-wide association studies (GWASs) from populations of European descent identified single nucleotide polymorphisms (SNPs) in aryl-hydrocarbon receptor (AHR) and cytochrome P450 1A1 and 1A2 (CYP1A1-CYP1A2) genes that are associated with habitual caffeine and coffee consumption. We examined whether these SNPs (AHR: rs6968865 and rs4410790; CYP1A1-CYP1A2: rs2472297 and rs2470893) and 6 additional tag SNPs in the AHR gene were associated with habitual caffeine consumption in a Costa Rican population. Subjects were from a case-control study of gene-diet interactions and myocardial infarction. Subjects with hypertension or missing information on smoking, caffeine intake, or genotype were excluded. Subjects were genotyped by using polymerase chain reaction with mass spectrometry-based detection, and caffeine intake was assessed by using a validated food-frequency questionnaire. Compared with subjects who consumed caffeine/d, subjects who consumed >400 mg caffeine/d were more likely to be carriers of the T, C, or T allele for rs6968865, rs4410790, and rs2472297, respectively. The corresponding ORs and 95% CIs were 1.41 (1.03, 1.93), 1.41 (1.04, 1.92), and 1.55 (1.01, 2.36). Multivariate-adjusted ORs (95% CIs) for rs6968865 were 1.44 (1.03, 2.00) for all subjects, 1.75 (1.16, 2.65) for nonsmokers, 1.15 (0.58, 2.30) for current smokers, 2.42 (1.45, 4.04) for subjects >57 y old, and 1.00 (0.65, 1.56) for subjects ≤57 y old. A similar effect modification was observed for rs4410790 but not for rs2472297. Our findings show that previous associations between SNPs in AHR and CYP1A1-CYP1A2 and caffeine and coffee consumption from GWASs in European populations are also observed in an ethnically distinct Costa Rican population, but age and smoking are important effect modifiers.

  6. Heterologous expression of human cytochrome P450 2E1 in HepG2 cell line

    Institute of Scientific and Technical Information of China (English)

    Jian Zhuge; Ye Luo; Ying-Nian Yu

    2003-01-01

    AIM: Human cytochrome P-450 2E1 (CYP2E1) takes part in the biotransformation of ethanol, acetone, many smallmolecule substrates and volatile anesthetics. CYP2E1 is involved in chemical activation of many carcinogens,procarcinogens, and toxicants. To assess the metabolic and toxicological characteristics of CYP2E1, we cloned CYP2E1 cDNA and established a HepG2 cell line stably expressing recombinant CYP 2E1.METHODS: Human CYP2E1 cDNA was amplified with reverse transcription-polymerase chain reaction (RT-PCR)from total RNAs extracted from human liver and cloned into pGEM-T vector. The cDNA segment was identified by DNA sequencing and subcloned into a mammalian expression vector pREP9. A transgenic cell line was established by transfecting the recombinant plasmid of pREP9-CYP2E1 to HepG2 cells. The expression of CYP2E1 mRNA was validated by RT-PCR. The enzyme activity of CYP2E1 catalyzing oxidation of 4-nitrophenol in postmitochondrial supernate (S9) fraction of the cells was determined by spectrophotometry. The metabolic activation of HepG2-CYP2E1 cells was assayed by N-nitrosodiethylamine (NDEA)cytotoxicity and micronucleus test.RESULTS: The cloned CYP2E1 cDNA segment was identical to that reported by Umeno et al(GenBank access No.J02843). HepG2-CYP2E1 cells expressed CYP2E1 mRNA and had 4-nitrophenol hydroxylase activity (0.162±0.025nmol.min-1.mg-1 S9 protein), which were undetectable in parent HepG2 cells. HepG2-CYP2E1 cells increased the cytotoxicity and micronucleus rate of NDEA in comparison with those of HepG2 cells.CONCLUSION: The cDNA of human CYP2E1 can be successfully cloned, and a cell line, HepG2-CYP2E1, which can efficiently express mRNA and has CYP2E1 activity, is established. The cell line is useful for testing the cytotoxicity,mutagenicity and metabolism of xenobiotics, which may possibly be activated or metabolized by CYP2E1.

  7. Effects of an ethanol extract of Brazilian green propolis on human cytochrome P450 enzyme activities in vitro.

    Science.gov (United States)

    Naramoto, Kyoko; Kato, Masashi; Ichihara, Kenji

    2014-11-19

    Supplement-drug interaction on CYP enzyme activity is occasionally found to cause clinically adverse events, and no report on interactions of propolis is available either in vitro or clinical. In this study, we tried to estimate the risk of an interaction between an ethanol extract of Brazilian green propolis (EEP-B55) and drugs in vitro and in vivo. The activities of CYP1A2, CYP2C9, CYP2C19, CYP2D6, and CYP3A4 were attenuated by EEP-B55 in a concentration-dependent manner, and artepillin C, kaempferide, dihydrokaempferide, isosakuranetin, and kaempferol were estimated to have potential for CYP inhibition. The IC50 values of artepillin C for each CYP were approximately 33-fold higher than its Cmax in the blood of rats after dosing with 5-fold the recommended daily intake of EEP-B55. These findings suggest that liver CYP enzyme activities are not markedly affected by artepillin C at the recommended daily intake of EEP-B55.

  8. Environmentally persistent free radical-containing particulate matter competitively inhibits metabolism by cytochrome P450 1A2

    Science.gov (United States)

    Reed, James R.; dela Cruz, Albert Leo N.; Lomnicki, Slawo M.; Backes, Wayne L.

    2015-01-01

    Combustion processes generate different types of particulate matter (PM) that can have deleterious effects on the pulmonary and cardiovascular systems. Environmentally persistent free radicals (EPFRs) represent a type of particulate matter that is generated after combustion of environmental wastes in the presence of redox-active metals and aromatic hydrocarbons. Cytochromes P450 (P450/CYP) are membrane-bound enzymes that are essential for the phase I metabolism of most lipophilic xenobiotics. The EPFR formed by chemisorption of 2-monochlorophenol to silica containing 5% copper oxide (MCP230) has been shown to generally inhibit the activities of different forms of P450s without affecting those of cytochrome P450 reductase and heme oxygenase-1. The mechanism of inhibition of rat liver microsomal CYP2D2 and purified rabbit CYP2B4 by MCP230 has been shown previously to be noncompetitive with respect to substrate. In this study, MCP230 was shown to competitively inhibit metabolism of 7-benzyl-4-trifluoromethylcoumarin and 7-ethoxyresorufin by the purified, reconstituted rabbit CYP1A2. MCP230 is at least 5- and 50-fold more potent as an inhibitor of CYP1A2 than silica containing 5% copper oxide and silica, respectively. Thus, even though PM generally inhibit multiple forms of P450, PM interacts differently with the forms of P450 resulting in different mechanisms of inhibition. P450s function as oligomeric complexes within the membrane. We also determined the mechanism by which PM inhibited metabolism by the mixed CYP1A2-CYP2B4 complex and found that the mechanism was purely competitive suggesting that the CYP2B4 is dramatically inhibited when bound to CYP1A2. PMID:26423927

  9. Environmentally persistent free radical-containing particulate matter competitively inhibits metabolism by cytochrome P450 1A2.

    Science.gov (United States)

    Reed, James R; dela Cruz, Albert Leo N; Lomnicki, Slawo M; Backes, Wayne L

    2015-12-01

    Combustion processes generate different types of particulate matter (PM) that can have deleterious effects on the pulmonary and cardiovascular systems. Environmentally persistent free radicals (EPFRs) represent a type of particulate matter that is generated after combustion of environmental wastes in the presence of redox-active metals and aromatic hydrocarbons. Cytochromes P450 (P450/CYP) are membrane-bound enzymes that are essential for the phase I metabolism of most lipophilic xenobiotics. The EPFR formed by chemisorption of 2-monochlorophenol to silica containing 5% copper oxide (MCP230) has been shown to generally inhibit the activities of different forms of P450s without affecting those of cytochrome P450 reductase and heme oxygenase-1. The mechanism of inhibition of rat liver microsomal CYP2D2 and purified rabbit CYP2B4 by MCP230 has been shown previously to be noncompetitive with respect to substrate. In this study, MCP230 was shown to competitively inhibit metabolism of 7-benzyl-4-trifluoromethylcoumarin and 7-ethoxyresorufin by the purified, reconstituted rabbit CYP1A2. MCP230 is at least 5- and 50-fold more potent as an inhibitor of CYP1A2 than silica containing 5% copper oxide and silica, respectively. Thus, even though PM generally inhibit multiple forms of P450, PM interacts differently with the forms of P450 resulting in different mechanisms of inhibition. P450s function as oligomeric complexes within the membrane. We also determined the mechanism by which PM inhibited metabolism by the mixed CYP1A2-CYP2B4 complex and found that the mechanism was purely competitive suggesting that the CYP2B4 is dramatically inhibited when bound to CYP1A2. Copyright © 2015 Elsevier Inc. All rights reserved.

  10. Conformational dynamics and the energetics of protein--ligand interactions: role of interdomain loop in human cytochrome P450 reductase.

    Science.gov (United States)

    Grunau, Alex; Geraki, Kalotina; Grossmann, J Günter; Gutierrez, Aldo

    2007-07-17

    A combination of mutagenesis, calorimetry, kinetics, and small-angle X-ray scattering (SAXS) has been used to study the mechanism of ligand binding energy propagation through human cytochrome P450 reductase (CPR). Remarkably, the energetics of 2',5'-ADP binding to R597 at the FAD-binding domain are affected by mutations taking place at an interdomain loop located 60 A away. Either deletion of a 7 amino acid long segment (T236-G237-E238-E239-S240-S241-I242) or its replacement by poly-proline repeats (5 and 10 residues) results in a significant increase in 2',5'-ADP enthalpy of binding (DeltaHB). This is accompanied by a decrease in the number of thermodynamic microstates available for the ligand-CPR complex. Moreover, the estimated heat capacity change (DeltaCp) for this interaction changes from -220 cal mol-1 K-1 in the wild-type enzyme to -580 cal mol-1 K-1 in the deletion mutant. Pre-steady-state kinetics measurements reveal a 50-fold decrease in the microscopic rate for interdomain (FAD --> FMN) electron transfer in the deletion mutant (kobs = 0.4 s-1). Multiple turnover cytochome c reduction assays indicate that these mutations impair the ability of the FMN-binding domain to shuttle electrons from the FAD-binding domain to the cytochrome partner. Binding of 2',5'-ADP to wild-type CPR triggers a large-scale structural rearrangement resulting in the complex having a more compact domain organization, and the maximum molecular dimension (Dmax) decreases from 110 A in ligand-free enzyme to 100 A in the ligand-bound CPR. The SAXS experiments also demonstrate that what is affected by the mutations is indeed the relative diffusional motion of the domains. Furthemore, ab initio shape reconstruction and homology modeling would suggest that-in the deletion mutant-hindering of domain motion occurs concomitantly with dimerization. The results presented here show that the energetics of this highly localized interaction (2',5'-ADP binding) have a global character, and are

  11. Modulation of rat and human cytochromes P450 involved in PhIP and 4-ABP activation by an aqueous extract of Phyllanthus orbicularis.

    Science.gov (United States)

    Ferrer, Mirle; Cristófol, Carles; Sánchez-Lamar, Angel; Fuentes, Jorge Luís; Barbé, Jordi; Llagostera, Montserrat

    2004-02-01

    Phyllanthus orbicularis HBK (Euphorbiaceae) is a medicinal plant, endemic to Cuba, whose aqueous extract has proven antimutagenic effects against hydrogen peroxide and some promutagenic aromatic amines (AAs), in addition to its antiviral properties. In this paper, antimutagenesis of this extract against two carcinogenic AAs, 2-amino-1-methyl-6-phenylimidazo[4,5-b]pyridine (PhIP) and 4-aminobiphenyl (4-ABP) has been studied. Liver microsomal fractions from both induced rats and humans were used to metabolise both procarcinogenic compounds in the Salmonella assay. The plant extract was effective in reducing the mutagenesis of these AAs, activated by both kinds of fractions. The optimal antimutagenic effect was obtained when both AAs were metabolised by human enzymes, with an almost total reduction of 4-ABP mutagenesis and a decrease of about 75% of PhIP mutagenicity. Mutagenicity of both AAs, activated by induced rat fraction, was only decreased by about 50%. Inhibition by plant extract of alkoxyresorufin O-dealkylation activities, dependent on CYP1A, of both fractions was determined. In accordance with the results obtained, the inhibition or modulation of CYP1A subfamily activities, and possibly of CYP1A2, is thought to be the main mechanism of antimutagenesis of the aqueous extract of Phyllanthus orbicularis against 4-ABP and PhIP.

  12. A High-Throughput (HTS) Assay for Enzyme Reaction Phenotyping in Human Recombinant P450 Enzymes Using LC-MS/MS.

    Science.gov (United States)

    Li, Xiaofeng; Suhar, Tom; Glass, Lateca; Rajaraman, Ganesh

    2014-01-01

    Enzyme reaction phenotyping is employed extensively during the early stages of drug discovery to identify the enzymes responsible for the metabolism of new chemical entities (NCEs). Early identification of metabolic pathways facilitates prediction of potential drug-drug interactions associated with enzyme polymorphism, induction, or inhibition, and aids in the design of clinical trials. Incubation of NCEs with human recombinant enzymes is a popular method for such work because of the specificity, simplicity, and high-throughput nature of this approach for phenotyping studies. The availability of a relative abundance factor and calculated intersystem extrapolation factor for the expressed recombinant enzymes facilitates easy scaling of in vitro data, enabling in vitro-in vivo extrapolation. Described in this unit is a high-throughput screen for identifying enzymes involved in the metabolism of NCEs. Emphasis is placed on the analysis of the human recombinant enzymes CYP1A2, CYP2C8, CYP2C9, CYP2C19, CYP2D6, CYP2B6, and CYP3A4, including the calculation of the intrinsic clearance for each.

  13. Association between CYP1A2 and CYP1B1 polymorphisms and colorectal cancer risk: a meta-analysis.

    Directory of Open Access Journals (Sweden)

    Xiao-Feng He

    Full Text Available BACKGROUND: The previous published data on the association between CYP1A2*F (rs762551, CYP1B1 Leu432Val (rs1056836, Asn453Ser (rs180040, and Arg48Gly (rs10012 polymorphisms and colorectal cancer risk remained controversial. METHODOLOGY/PRINCIPAL FINDINGS: The purpose of this study is to evaluate the role of CYP1A2*F, CYP1B1 Leu432Val, Asn453Ser, and Arg48Gly genotypes in colorectal cancer susceptibility. We performed a meta-analysis on all the eligible studies that provided 5,817 cases and 6,544 controls for CYP1A2*F (from 13 studies, 9219 cases and 10406 controls for CYP1B1 Leu432Val (from 12 studies, 6840 cases and 7761 controls for CYP1B1 Asn453Ser (from 8 studies, and 4302 cases and 4791 controls for CYP1B1Arg48Gly (from 6 studies. Overall, no significant association was found between CYP1A2*F, CYP1B1 Leu432Val, Asn453Ser, and Arg48Gly and colorectal cancer risk when all the eligible studies were pooled into the meta-analysis. And in the subgroup by ethnicity and source of controls, no evidence of significant association was observed in any subgroup analysis. CONCLUSIONS/SIGNIFICANCE: In summary, this meta-analysis indicates that CYP1A2*F, CYP1B1 Leu432Val, Asn453Ser, and Arg48Gly polymorphisms do not support an association with colorectal cancer, and further studies are needed to investigate the association. In addition, our work also points out the importance of new studies for CYP1A2*F polymorphism in Asians, because high heterogeneity was found (dominant model: I(2  = 81.3%; heterozygote model: I(2  = 79.0.

  14. Comparison of metabolism of sesamin and episesamin by drug-metabolizing enzymes in human liver.

    Science.gov (United States)

    Yasuda, Kaori; Ikushiro, Shinichi; Wakayama, Shuto; Itoh, Toshimasa; Yamamoto, Keiko; Kamakura, Masaki; Munetsuna, Eiji; Ohta, Miho; Sakaki, Toshiyuki

    2012-10-01

    Sesamin and episesamin are two epimeric lignans that are found in refined sesame oil. Commercially available sesamin supplements contain both sesamin and episesamin at an approximate 1:1 ratio. Our previous study clarified the sequential metabolism of sesamin by cytochrome P450 (P450) and UDP-glucuronosyltransferase in human liver. In addition, we revealed that sesamin caused a mechanism-based inhibition (MBI) of CYP2C9, the P450 enzyme responsible for sesamin monocatecholization. In the present study, we compared the metabolism and the MBI of episesamin with those of sesamin. Episesamin was first metabolized to the two epimers of monocatechol, S- and R-monocatechols in human liver microsomes. The P450 enzymes responsible for S- and R-monocatechol formation were CYP2C9 and CYP1A2, respectively. The contribution of CYP2C9 was much larger than that of CYP1A2 in sesamin metabolism, whereas the contribution of CYP2C9 was almost equal to that of CYP1A2 in episesamin metabolism. Docking of episesamin to the active site of CYP1A2 explained the stereoselectivity in CYP1A2-dependent episesamin monocatecholization. Similar to sesamin, the episesamin S- and R-monocatechols were further metabolized to dicatechol, glucuronide, and methylate metabolites in human liver; however, the contribution of each reaction was significantly different between sesamin and episesamin. The liver microsomes from CYP2C19 ultra-rapid metabolizers showed a significant amount of episesamin dicatechol. In this study, we have revealed significantly different metabolism by P450, UDP-glucuronosyltransferase, and catechol-O-methyltransferase for sesamin and episesamin, resulting in different biological effects.

  15. [Evaluation of pharmacokinetic interaction of aphobazole with CYP1A2 drug-substrate in experiments].

    Science.gov (United States)

    Novitskaia, Ia G; Litvin, A A; Viglinskaia, A O; Zherdev, V P

    2013-01-01

    The effect of aphobazole on CYP1A2 (drug-marker caffeine) was studied in rats. Aphobazole was administered orally at doses 5 and 25 mg/kg, caffeine 50 mg/kg. The metabolic ratios (MR) for the caffeine metabolites (theobromine and paraxanthine) were accounted. After aphobazole administration at the effective, anxiolytic dose (5 mg/kg) for 4 days (3 times per day every 3 hours) neither the inhibiting nor the inducing effects on NOD1A2 was revealed. Increasing the aphobazole dose up to 25 mg/kg after 2 days repeated administrations of the drug made it possible to reveal a moderate inducing effect. Longer aphobazole administration (4 days), the inducing effect is amplified. Since the MR values on theobromine and paraxanthine after 2-day administration aphobazole exceed similar values in the control of 2.5 and 3.3 times, respectively. MR values after the 4-days aphobazole administration in dose 25 mg/kg exceed similar values in the control of 4.2 times for theobromine and in 6.1 times for paraxanthine.

  16. Effects of mexiletine, a CYP1A2 inhibitor, on tizanidine pharmacokinetics and pharmacodynamics.

    Science.gov (United States)

    Momo, Kenji; Homma, Masato; Osaka, Yoshiko; Inomata, Shin-ichi; Tanaka, Makoto; Kohda, Yukinao

    2010-03-01

    The aim of this study was to determine whether mexiletine, a CYP1A2 inhibitor, altered the pharmacokinetics and pharmacodynamics of tizanidine. The pharmacokinetics of tizanidine were examined in an open-label study in 12 healthy participants after a single dose of tizanidine (2 mg) with and without mexiletine coadministration (50 mg, 3 times as a pretreatment for a day and 2 times on the study day). Compared with tizanidine alone, mexiletine coadministration increased the peak plasma concentration (1.8 +/- 0.8 vs 5.3 +/- 1.8 ng/mL), area under the curve (4.5 +/- 2.2 vs 15.4 +/- 6.5 ng x h/mL), and the half-life (1.3 +/- 0.2 vs 1.8 +/- 0.7 h) of tizanidine, respectively (P < .05). Reduction in systolic blood pressure (-10 +/- 8 vs -24 +/- 7 mm Hg) and diastolic blood pressure (-10 +/- 7 vs -18 +/- 8 mm Hg) after tizanidine administration was also significantly enhanced by coadministration of mexiletine (P < .01). Of the 15 patients treated with tizanidine and mexiletine, 4 suffered tizanidine-induced adverse effects such as drowsiness and dry mouth in the retrospective survey. Present results suggested that coadministration of mexiletine increased blood tizanidine concentrations and enhanced tizanidine pharmacodynamics in terms of reduction in blood pressure and adverse symptoms.

  17. Assessment of Protein Binding of 5-Hydroxythalidomide Bioactivated in Humanized Mice with Human P450 3A-Chromosome or Hepatocytes by Two-Dimensional Electrophoresis/Accelerator Mass Spectrometry.

    Science.gov (United States)

    Yamazaki, Hiroshi; Suemizu, Hiroshi; Kazuki, Yasuhiro; Oofusa, Ken; Kuribayashi, Shunji; Shimizu, Makiko; Ninomiya, Shinichi; Horie, Toru; Shibata, Norio; Guengerich, F Peter

    2016-08-15

    Bioactivation of 5-hydroxy-[carbonyl-(14)C]thalidomide, a known metabolite of thalidomide, by human artificial or native cytochrome P450 3A enzymes, and nonspecific binding in livers of mice was assessed using two-dimensional electrophoresis combined with accelerator mass spectrometry. The apparent major target proteins were liver microsomal cytochrome c oxidase subunit 6B1 and ATP synthase subunit α in mice containing humanized P450 3A genes or transplanted humanized liver. Liver cytosolic retinal dehydrogenase 1 and glutathione transferase A1 were targets in humanized mice with P450 3A and hepatocytes, respectively. 5-Hydroxythalidomide is bioactivated by human P450 3A enzymes and trapped with proteins nonspecifically in humanized mice.

  18. Molecular evolutionary dynamics of cytochrome P450 monooxygenases across kingdoms: Special focus on mycobacterial P450s.

    Science.gov (United States)

    Parvez, Mohammad; Qhanya, Lehlohonolo Benedict; Mthakathi, Ntsane Trevor; Kgosiemang, Ipeleng Kopano Rosinah; Bamal, Hans Denis; Pagadala, Nataraj Sekhar; Xie, Ting; Yang, Haoran; Chen, Hengye; Theron, Chrispian William; Monyaki, Richie; Raselemane, Seiso Caiphus; Salewe, Vuyani; Mongale, Bogadi Lorato; Matowane, Retshedisitswe Godfrey; Abdalla, Sara Mohamed Hasaan; Booi, Wool Isaac; van Wyk, Mari; Olivier, Dedré; Boucher, Charlotte E; Nelson, David R; Tuszynski, Jack A; Blackburn, Jonathan Michael; Yu, Jae-Hyuk; Mashele, Samson Sitheni; Chen, Wanping; Syed, Khajamohiddin

    2016-09-12

    Since the initial identification of cytochrome P450 monooxygenases (CYPs/P450s), great progress has been made in understanding their structure-function relationship, diversity and application in producing compounds beneficial to humans. However, the molecular evolution of P450s in terms of their dynamics both at protein and DNA levels and functional conservation across kingdoms still needs investigation. In this study, we analyzed 17 598 P450s belonging to 113 P450 families (bacteria -42; fungi -19; plant -28; animal -22; plant and animal -1 and common P450 family -1) and found highly conserved and rapidly evolving P450 families. Results suggested that bacterial P450s, particularly P450s belonging to mycobacteria, are highly conserved both at protein and DNA levels. Mycobacteria possess the highest P450 diversity percentage compared to other microbes and have a high coverage of P450s (≥1%) in their genomes, as found in fungi and plants. Phylogenetic and functional analyses revealed the functional conservation of P450s despite belonging to different biological kingdoms, suggesting the adherence of P450s to their innate function such as their involvement in either generation or oxidation of steroids and structurally related molecules, fatty acids and terpenoids. This study's results offer new understanding of the dynamic structural nature of P450s.

  19. Computational prediction of binding affinity for CYP1A2-ligand complexes using empirical free energy calculations

    DEFF Research Database (Denmark)

    Poongavanam, Vasanthanathan; Olsen, Lars; Jørgensen, Flemming Steen

    2010-01-01

    , and methods based on statistical mechanics. In the present investigation, we started from an LIE model to predict the binding free energy of structurally diverse compounds of cytochrome P450 1A2 ligands, one of the important human metabolizing isoforms of the cytochrome P450 family. The data set includes both...... substrates and inhibitors. It appears that the electrostatic contribution to the binding free energy becomes negligible in this particular protein and a simple empirical model was derived, based on a training set of eight compounds. The root mean square error for the training set was 3.7 kJ/mol. Subsequent......Predicting binding affinities for receptor-ligand complexes is still one of the challenging processes in computational structure-based ligand design. Many computational methods have been developed to achieve this goal, such as docking and scoring methods, the linear interaction energy (LIE) method...

  20. Effect of hepatitis C virus infection on the mRNA expression of drug transporters and cytochrome p450 enzymes in chimeric mice with humanized liver.

    Science.gov (United States)

    Kikuchi, Ryota; McCown, Matthew; Olson, Pamela; Tateno, Chise; Morikawa, Yoshio; Katoh, Yumiko; Bourdet, David L; Monshouwer, Mario; Fretland, Adrian J

    2010-11-01

    The expression of drug transporters and metabolizing enzymes is a primary determinant of drug disposition. Chimeric mice with humanized liver, including PXB mice, are an available model that is permissive to the in vivo infection of hepatitis C virus (HCV), thus being a promising tool for investigational studies in development of new antiviral molecules. To investigate the potential of HCV infection to alter the pharmacokinetics of small molecule antiviral therapeutic agents in PXB mice, we have comprehensively determined the mRNA expression profiles of human ATP-binding cassette (ABC) transporters, solute carrier (SLC) transporters, and cytochrome P450 (P450) enzymes in the livers of these mice under noninfected and HCV-infected conditions. Infection of PXB mice with HCV resulted in an increase in the mRNA expression levels of a series of interferon-stimulated genes in the liver. For the majority of genes involved in drug disposition, minor differences in the mRNA expression of ABC and SLC transporters as well as P450s between the noninfected and HCV-infected groups were observed. The exceptions were statistically significantly higher expression of multidrug resistance-associated protein 4 and organic anion-transporting polypeptide 2B1 and lower expression of organic cation transporter 1 and CYP2D6 in HCV-infected mice. Furthermore, the enzymatic activities of the major human P450s were, in general, comparable in the two experimental groups. These data suggest that the pharmacokinetic properties of small molecule antiviral therapies in HCV-infected PXB mice are likely to be similar to those in noninfected PXB mice. However, caution is needed in the translation of this relationship to HCV-infected patients as the PXB mouse model does not accurately reflect the pathology of patients with chronic HCV infection.

  1. Polymorphisms in the Human Cytochrome P450 and Arylamine N-Acetyltransferase: Susceptibility to Head and Neck Cancers

    Directory of Open Access Journals (Sweden)

    Rim Khlifi

    2013-01-01

    Full Text Available The occurrence of head and neck cancer (HNC is associated with smoking and alcohol drinking. Tobacco smoking exposes smokers to a series of carcinogenic chemicals. Cytochrome P450 enzymes (CYP450s, such as CYP1A1, CYP1B1, and CYP2D6, usually metabolize carcinogens to their inactive derivatives, but they occasionally convert the chemicals to more potent carcinogens. In addition, via CYP450 (CYP2E1 oxidase, alcohol is metabolized to acetaldehyde, a highly toxic compound, which plays an important role in carcinogenesis. Furthermore, two N-acetyltransferase isozymes (NATs, NAT1 and NAT2, are polymorphic and catalyze both N-acetylation and O-acetylation of aromatic and heterocyclic amine carcinogens. Genetic polymorphisms are associated with a number of enzymes involved in the metabolism of carcinogens important in the induction of HNC. It has been suggested that such polymorphisms may be linked to cancer susceptibility. In this paper, we select four cytochrome P450 enzymes (CYP1A1, CYP1BA1, CYP2D6, and CYP2E1, and two N-acetyltransferase isozymes (NAT1 and NAT2 in order to summarize and analyze findings from the literature related to HNC risk by focusing on (i the interaction between these genes and the environment, (ii the impact of genetic defect on protein activity and/or expression, and (iii the eventual involvement of race in such associations.

  2. Selective inhibition of cytochrome P450 2D6 by Sarpogrelate and its active metabolite, M-1, in human liver microsomes.

    Science.gov (United States)

    Cho, Doo-Yeoun; Bae, Soo Hyeon; Lee, Joeng Kee; Kim, Yang Weon; Kim, Bom-Taeck; Bae, Soo Kyung

    2014-01-01

    The present study was performed to evaluate the in vitro inhibitory potential of sarpogrelate and its active metabolite, M-1, on the activities of nine human cytochrome (CYP) isoforms. Using a cocktail assay, the effects of sarpogrelate on nine CYP isoforms and M-1 were measured by specific marker reactions in human liver microsomes. Sarpogrelate potently and selectively inhibited CYP2D6-mediated dextromethorphan O-demethylation with an IC50 (Ki) value of 3.05 μM (1.24 μM), in a competitive manner. M-1 also markedly inhibited CYP2D6 activity; its inhibitory effect with an IC50 (Ki) value of 0.201 μM (0.120 μM) was more potent than that of sarpogrelate, and was similarly potent as quinidine (Ki, 0.129 μM), a well-known typical CYP2D6 inhibitor. In addition, sarpogrelate and M-1 strongly inhibited both CYP2D6-catalyzed bufuralol 1'-hydroxylation and metoprolol α-hydroxylation activities. However, sarpogrelate and M-1 showed no apparent inhibition of the other following eight CYPs: CYP1A2, CYP2A6, CYP2B6, CYP2C8, CYP2C9, CYP2C19, CYP2E1, or CYP3A4/5. Upon 30-minute preincubation of human liver microsomes with sarpogrelate or M-1 in the presence of NADPH, no obvious shift in IC50 was observed in terms of inhibition of the nine CYP activities, suggesting that sarpogrelate and M-1 are not time-dependent inactivators. Sarpogrelate strongly inhibited the activity of CYP2D6 at clinically relevant concentrations in human liver microsomes. These observations suggest that sarpogrelate could have an effect on the metabolic clearance of drugs possessing CYP2D6-catalyzed metabolism as a major clearance pathway, thereby eliciting pharmacokinetic drug-drug interactions.

  3. In vitro assessment of cytochrome P450 inhibition and induction potential of tanespimycin and its major metabolite, 17-amino-17-demethoxygeldanamycin.

    Science.gov (United States)

    Gan, Jinping; Liu-Kreyche, Peggy; Humphreys, W Griffith

    2012-01-01

    To assess the inhibition and induction potential of tanespimycin and its major metabolite, 17-amino-17-demethoxygeldanamycin (17-AG) on cytochrome P450 (CYP) enzymes. The inhibitory effect of tanespimycin and 17-AG on various CYP enzymes was determined in human liver microsomes. The inductive effects of tanespimycin and 17-AG on CYP1A2, CYP2B6, and CYP3A4/5 were determined in cultured primary human hepatocytes. Tanespimycin did not inhibit the activities of CYP1A2, 2A6, 2B6, and 2E1 up to a concentration of 60 μM, while it moderately inhibited CYP3A4/5 and 2C19, and weakly inhibited CYP2C8, 2C9, and 2D6. In addition, its inhibition on CYP3A4/5 was time-dependent. 17-AG moderately inhibited the activities of CYP3A4/5 and CYP2C19, but did not inhibit other CYPs up to a concentration of 30 μM. The inhibition of CYP3A4/5 by 17-AG was not time-dependent. Tanespimycin and 17-AG did not significantly induce the activities of CYP1A2, CYP2B6, or CYP3A4/5 in cultured human hepatocytes at concentrations up to 40 and 20 μM for tanespimycin and 17-AG, respectively. Tanespimycin together with its active metabolite, 17-AG are moderate inhibitors of CYP3A4/5 and CYP2C19, but not inducers of CYPs. Therefore, co-administration of tanespimycin has the potential to increase the exposure of substrates of CYP2C19 and CYP3A4/5.

  4. The cytochrome p450 homepage.

    Science.gov (United States)

    Nelson, David R

    2009-10-01

    The Cytochrome P450 Homepage is a universal resource for nomenclature and sequence information on cytochrome P450 ( CYP ) genes. The site has been in continuous operation since February 1995. Currently, naming information for 11,512 CYPs are available on the web pages. The P450 sequences are manually curated by David Nelson, and the nomenclature system conforms to an evolutionary scheme such that members of CYP families and subfamilies share common ancestors. The organisation and content of the Homepage are described.

  5. The revised human liver cytochrome P450 "Pie": absolute protein quantification of CYP4F and CYP3A enzymes using targeted quantitative proteomics.

    Science.gov (United States)

    Michaels, Scott; Wang, Michael Zhuo

    2014-08-01

    The CYP4F subfamily of enzymes has been identified recently to be involved in the metabolism of endogenous compounds (arachidonic acid and leukotriene B4), nutrients (vitamins K1 and E), and xenobiotics (pafuramidine and fingolimod). CYP4F2 and CYP4F3B are reported to be expressed in the human liver. However, absolute concentrations of these enzymes in human liver microsomes (HLMs) and their interindividual variability have yet to be determined because of the lack of specific antibodies. Here, an liquid chromatography with tandem mass spectrometry (LC-MS/MS)-based targeted quantitative proteomic approach was employed to determine the absolute protein concentrations of CYP4F2 and CYP4F3B compared with CYP3A in two panels of HLMs (n = 31). As a result, the human hepatic cytochrome P450 (P450) "pie" has been revised to include the contribution of CYP4F enzymes, which amounts to 15% of the total hepatic cytochrome P450 enzymes. CYP4F3B displayed low interindividual variability (3.3-fold) in the HLM panels whereas CYP4F2 displayed large variability (21-fold). However, CYP4F2 variability decreased to 3.4-fold if the two donors with the lowest expression were excluded. In contrast, CYP3A exhibited 29-fold interindividual variability in the same HLM panels. The proposed marker reaction for CYP4F enzymes pafuramidine/DB289 M1 formation did not correlate with CYP4F protein content, suggesting alternate metabolic pathways for DB289 M1 formation in HLMs. In conclusion, CYP4F enzymes are highly expressed in the human liver and their physiologic and pharmacologic roles warrant further investigation.

  6. Association of CYP2D6 and CYP1A2 gene polymorphism with tardive dyskinesia in Chinese schizophrenic patients

    Institute of Scientific and Technical Information of China (English)

    Yan FU; Chang-he FAN; He-huang DENG; San-hong HU; De-peng LV; Li-hua LI; Jun-jie WANG; Xin-qiao LU

    2006-01-01

    Aim:To investigate the possible association of the CYP2D6 gene C100T polymorphism and the CYP1A2 gene C163A polymorphism with tardive dyskinesia (TD) in Chinese patients with schizophrenia.Methods:The recruited schizophrenic patients were assessed with the Abnormal Involuntary Movement Scale (AIMS),and divided into groups with TD(n=91)and without TD(n=91)according to the AIMS score.Polymorphisms of the CYP2D6 and CYP1A2 genes were determined by polymerase chain reaction(PER)-restriction fragment length polymorphism(RFLP).Results:No allele frequencies deviated from Hardy-Weinberg equilibrium.No significant differences in genotypes frequencies of the CYP2D C100T polymorphism were observed between patients with TD and without TD (x2=4.078,P>0.05),but patients with TD had a significant excess of the T allele compared with those without TD(x2=4.28,P<0.05).Moreover,the frequency of the CYP1A2 C allele in patients with TD was significantly higher than that in those without TD(x2=6.38,P<0.05).An association between TD and the CyP2D6 100T and CYP1A2 163C alleles was observed.Additionally,there were no differences in the mean AIMS scores among different genotypes in TD patients as a group or in smokers.The results of logistic regression anatysls demonstrated that mean age and duration of illness were risk factors for TD,but not sex,cumulative exposure to neuroleptic drugs in years,CYP2D6 or CYP1A2 genotype.Conclusion:The C100T polymorphism of the CYP2D6 gene and the C163A polymorphism of the CYP1A2 gene may be associated with neuroleptic drug-induced tardive dyskinesia in Chinese patients with schizophrenia.However,genetic factors have a weaker association with susceptibility to TD compared with mean age and duration of illness.

  7. 丹参酚酸A对大鼠肝微粒体细胞色素P450酶系的影响%Effects of salvianolic acid A on rat liver microsomal cytochrome P450 system

    Institute of Scientific and Technical Information of China (English)

    郭海方; 邹晓丽; 许卉; 刘珂

    2010-01-01

    目的:研究丹参酚酸A对大鼠肝微粒体细胞色素P450和细胞色素b_5含量以及CYP1A2和CYP2E1活性的影响.方法:将大鼠分成溶剂对照组和丹参酚酸A给药组,每组10只,雌雄各半,丹参酚酸A给药组尾静脉注射给予丹参酚酸A 20 mg·kg~(-1)·d~(-1),连续给药5 d;溶剂对照组给予相同剂量的溶剂,紫外分光光度法测定大鼠肝微粒体细胞色素P450和细胞色素b_5含量;探针底物法评价CYP1A2和CYP2E1的活性.结果:丹参酚酸A尾静脉注射连续给药5 d后,大鼠细胞色素P450和细胞色素b_5含量与对照组比较均无显著性差异;CYP1A2和CYP2E1的活性与对照组比较也无显著性差异.结论:丹参酚酸A对CYP1A2和CYP2E1没有诱导或抑制作用,与经过CYP1A2和CYP2E1代谢的药物发生相互作用的可能性较小.

  8. The anticarcinogen 3,3'-diindolylmethane is an inhibitor of cytochrome P-450.

    Science.gov (United States)

    Stresser, D M; Bjeldanes, L F; Bailey, G S; Williams, D E

    1995-08-01

    Dietary indole-3-carbinol inhibits carcinogenesis in rodents and trout. Several mechanisms of inhibition may exist. We reported previously that 3,3'-diindolylmethane, an in vivo derivative of indole-3-carbinol, is a potent noncompetitive inhibitor of trout cytochrome P450 (CYP) 1A-dependent ethoxyresorufin O-deethylase with Ki values in the low micromolar range. We now report a similar potent inhibition by 3,3'-diindolylmethane of rat and human CYP1A1, human CYP1A2, and rat CYP2B1 using various CYP-specific or preferential activity assays. 3,3'-Diindolylmethane also inhibited in vitro CYP-mediated metabolism of the ubiquitous food contaminant and potent hepatocarcinogen, aflatoxin B1. There was no inhibition of cytochrome c reductase. In addition, we found 3,3'-diindolylmethane to be a substrate for rat hepatic microsomal monooxygenase(s) and tentatively identified a monohydroxylated metabolite. These observations indicate that 3,3'-diindolylmethane can inhibit the catalytic activities of a range of CYP isoforms from lower and higher vertebrates in vitro. This broadly based inhibition of CYP-mediated activation of procarcinogens may be an indole-3-carbinol anticarcinogenic mechanism applicable to all species, including humans.

  9. Inhibitory effects of curcumin on activity of cytochrome P450 2C9 enzyme in human and 2C11 in rat liver microsomes.

    Science.gov (United States)

    Wang, Zhe; Sun, Wei; Huang, Cheng-Ke; Wang, Li; Xia, Meng-Ming; Cui, Xiao; Hu, Guo-Xin; Wang, Zeng-Shou

    2015-04-01

    Cytochrome P450 2C9 (CYP2C9), one of the most important phase I drug metabolizing enzymes, could catalyze the reactions that convert diclofenanc into diclofenac 4'-hydroxylation. Evaluation of the inhibitory effects of compounds on CYP2C9 is clinically important because inhibition of CYP2C9 could result in serious drug-drug interactions. The objective of this work was to investigate the effects of curcumin on CYP2C9 in human and cytochrome P450 2C11 (CYP2C11) in rat liver microsomes. The results showed that curcumin inhibited CYP2C9 activity (10 µmol L(-1) diclofenac) with half-maximal inhibition or a half-maximal inhibitory concentration (IC50) of 15.25 µmol L(-1) and Ki = 4.473 µmol L(-1) in human liver microsomes. Curcumin's mode of action on CYP2C9 activity was noncompetitive for the substrate diclofenanc and uncompetitive for the cofactor NADPH. In contrast to its potent inhibition of CYP2C9 in human, diclofenanc had lesser effects on CYP2C11 in rat, with an IC50 ≥100 µmol L(-1). The observations imply that curcumin has the inhibitory effects on CYP2C9 activity in human. These in vitro findings suggest that more attention should be paid to special clinical caution when intake of curcumin combined with other drugs in treatment.

  10. The role of human cytochrome P450 enzymes in the formation of 2-hydroxymetronidazole: CYP2A6 is the high affinity (low Km) catalyst.

    Science.gov (United States)

    Pearce, Robin E; Cohen-Wolkowiez, Michael; Sampson, Mario R; Kearns, Gregory L

    2013-09-01

    Despite metronidazole's widespread clinical use since the 1960s, the specific enzymes involved in its biotransformation have not been previously identified. Hence, in vitro studies were conducted to identify and characterize the cytochrome P450 enzymes involved in the formation of the major metabolite, 2-hydroxymetronidazole. Formation of 2-hydroxymetronidazole in human liver microsomes was consistent with biphasic, Michaelis-Menten kinetics. Although several cDNA-expressed P450 enzymes catalyzed 2-hydroxymetronidazole formation at a supratherapeutic concentration of metronidazole (2000 μM), at a "therapeutic concentration" of 100 μM only CYPs 2A6, 3A4, 3A5, and 3A7 catalyzed metronidazole 2-hydroxylation at rates substantially greater than control vector, and CYP2A6 catalyzed 2-hydroxymetronidazole formation at rates 6-fold higher than the next most active enzyme. Kinetic studies with these recombinant enzymes revealed that CYP2A6 has a Km = 289 μM which is comparable to the Km for the high-affinity (low-Km) enzyme in human liver microsomes, whereas the Km values for the CYP3A enzymes corresponded with the low-affinity (high-Km) component. The sample-to-sample variation in 2-hydroxymetronidazole formation correlated significantly with CYP2A6 activity (r ≥ 0.970, P concentrations of 100 and 300 μM. Selective chemical inhibitors of CYP2A6 inhibited metronidazole 2-hydroxylation in a concentration-dependent manner and inhibitory antibodies against CYP2A6 virtually eliminated metronidazole 2-hydroxylation (>99%). Chemical and antibody inhibitors of other P450 enzymes had little or no effect on metronidazole 2-hydroxylation. These results suggest that CYP2A6 is the primary catalyst responsible for the 2-hydroxylation of metronidazole, a reaction that may function as a marker of CYP2A6 activity both in vitro and in vivo.

  11. Regioselective differences in C(8)- and N-oxidation of 2-amino-3,8-dimethylimidazo[4,5-f]quinoxaline by human and rat liver microsomes and cytochromes P450 1A2.

    Science.gov (United States)

    Turesky, R J; Parisod, V; Huynh-Ba, T; Langouët, S; Guengerich, F P

    2001-07-01

    The metabolism of the mutagen 2-amino-3,8-dimethylimidazo[4,5-f]quinoxaline (MeIQx) was investigated with human and rat liver microsomes, recombinant human cytochrome P450 1A2 (P450 1A2) expressed in Escherichia coli cells, and rat P450 1A2. Human liver microsomes and human P450 1A2 catalyzed the oxidation of the exocyclic amine group of MeIQx to form the genotoxic product 2-(hydroxyamino)-3,8-dimethylimidazo[4,5-f]quinoxaline (HONH-MeIQx). Human P450 1A2 also catalyzed the oxidation of C(8)-methyl group of MeIQx to form 2-amino-(8-hydroxymethyl)-3-methylimidazo[4,5-f]quinoxaline (8-CH(2)OH-IQx), 2-amino-3-methylimidazo[4,5-f]quinoxaline-8-carbaldehyde (IQx-8-CHO), and 2-amino-3-methylimidazo[4,5-f]quinoxaline-8-carboxylic acid (IQx-8-COOH). Thus, chemically stable C(8)-oxidation products of MeIQx may be useful biomarkers of P450 1A2 activity in humans. Rat liver microsomes were 10-15-fold less active than the human counterpart at both N-oxidation and C(8)-oxidation of MeIQx when expressed as nanomoles of product formed per minute per nanomoles of P450 1A2. Differences in regioselective oxidation of MeIQx were also observed with human and rat liver microsomes and the respective P450 1A2 orthologs. In contrast to human liver microsomes and P450 1A2, rat liver microsomes and purified rat P4501A2 were unable to catalyze the oxidation of MeIQx to the carboxylic derivative IQx-8-COOH, an important detoxication product formed in humans. However, rat liver microsomes and rat P4501A2, but not human liver microsomes or human P450 1A2, extensively catalyzed ring oxidation at the C-5 position of MeIQx to form the detoxication product 2-amino-3,8-dimethyl-5-hydroxyimidazo[4,5-f]quinoxaline (5-HO-MeIQx). There are important differences between human and rat P450 1A2, both in catalytic activities and oxidation pathways of MeIQx, that may affect the biological activity of this carcinogen and must be considered when assessing human health risk.

  12. Association of coffee consumption and CYP1A2 polymorphism with risk of impaired fasting glucose in hypertensive patients.

    Science.gov (United States)

    Palatini, Paolo; Benetti, Elisabetta; Mos, Lucio; Garavelli, Guido; Mazzer, Adriano; Cozzio, Susanna; Fania, Claudio; Casiglia, Edoardo

    2015-03-01

    Whether and how coffee use influences glucose metabolism is still a matter for debate. We investigated whether baseline coffee consumption is longitudinally associated with risk of impaired fasting glucose in a cohort of 18-to-45 year old subjects screened for stage 1 hypertension and whether CYP1A2 polymorphism modulates this association. A total of 1,180 nondiabetic patients attending 17 hospital centers were included. Seventy-four percent of our subjects drank coffee. Among the coffee drinkers, 87% drank 1-3 cups/day (moderate drinkers), and 13% drank over 3 cups/day (heavy drinkers). Genotyping of CYP1A2 SNP was performed by real time PCR in 639 subjects. At the end of a median follow-up of 6.1 years, impaired fasting glucose was found in 24.0% of the subjects. In a multivariable Cox regression coffee use was a predictor of impaired fasting glucose at study end, with a hazard ratio (HR) of 1.3 (95% CI 0.97-1.8) in moderate coffee drinkers and of 2.3 (1.5-3.5) in heavy drinkers compared to abstainers. Among the subjects stratified by CYP1A2 genotype, heavy coffee drinkers carriers of the slow *1F allele (59%) had a higher adjusted risk of impaired fasting glucose (HR 2.8, 95% CI 1.3-5.9) compared to abstainers whereas this association was of borderline statistical significance among the homozygous for the A allele (HR 1.7, 95% CI 0.8-3.8). These data show that coffee consumption increases the risk of impaired fasting glucose in hypertension particularly among carriers of the slow CYP1A2 *1F allele.

  13. Study of in vitro metabolism of m-nisoldipine in human liver microsomes and recombinant cytochrome P450 enzymes by liquid chromatography-mass spectrometry.

    Science.gov (United States)

    Yuan, Lin; Jia, Peipei; Sun, Yupeng; Zhao, Chengcheng; Zhi, Xuran; Sheng, Ning; Zhang, Lantong

    2014-08-01

    This is a report about the investigation of the metabolic fate of m-nisoldipine in human liver microsomes and the recombinant cytochrome P450 enzymes by using LC-MS/MS. A sensitive and reliable LC-MS/MS method was developed to obtain a rapid and complete characterization of new metabolites and the metabolism pathways. The analytes were separated on a reversed phase C18 column with acetonitrile and 0.1% aqueous formic acid as the mobile phase. Tandem mass spectrometry with positive electrospray ionization was used to enable the structural characterization of the metabolites. A total of 10 metabolites were characterized with proposed structures in the incubation of human liver microsomes by comparing their retention times and spectral patterns with those of the parent drug. Dehydrogenation of the dihydropyridine core and reactions of side chains such as hydroxylation and hydrolysis of ester bonds were the major metabolic pathways. The specific cytochrome P450 (CYP) enzymes responsible for m-nisoldipine metabolites were identified using chemical inhibition and cDNA expressed CYP enzymes. The results indicated that CYP2C19 and CYP3A4 might play major roles in the metabolism of m-nisoldipine in human liver microsomes.

  14. 闽南地区抑郁症患者CYP1A2和CYP2D6基因多态性与度洛西汀疗效的关联研究%Association of CYP1A2 and CYP2D6 gene polymorphism with therapeutic efficacy of duloxetine on depression in southern region of Fujian

    Institute of Scientific and Technical Information of China (English)

    陈进东; 徐象珍; 陈彬彬

    2015-01-01

    0.69 respectively and there was significant difference(F=3.38, P<0.05).CC group was significantly lower than TT group(P<0.05).Conclusion Among the 3 loci studied,only CYP2D6 * 10 locus within CYP2D6 gene can affect blood concentration,efficacy and adverse effects of duloxetine,which indicate that CYP2D6 gene polymorphism may contribute to therapeutic efficacy of duloxetine on depression in southern region of Fujian.%目的 探讨细胞色素P450(CYP) 1A2*1C、CYP1A2* 1F及CYP2D6* 10基因多态性对度洛西汀血药浓度及对抑郁症疗效的影响.方法 纳入82例首发或入组前1个月内未服用抗抑郁药的复发抑郁症患者,予同一剂量度洛西汀(20~60 mg)治疗两周,高效液相色谱-质谱联用检测度洛西汀的稳态血药浓度,基因测序对相关基因进行分型,汉密尔顿抑郁量表(HAMD)评定临床疗效,副反应量表(TESS)评定不良反应,分析携带不同单核苷酸多态性(SNP)对度洛西汀治疗抑郁症疗效的影响.结果 CYP1A2* 1C基因型可分为GG、GA和AA型三组.CYP1A2* 1F基因型可分为CC、CA和AA型三组.对CYP1A2* 1C和CYP1A2* 1F,三组血药浓度、剂量校正浓度、HAMD减分率和TESS评分之间均差异无统计学意义(P>0.05).CYP2D6* 10基因型可分为CC、CT和TT型三组.三组血药浓度分别为(13.89±3.22)ng· ml-1、(16.08±4.24) ng·ml-1、(17.25±4.62) ng·ml-1,三组之间差异有统计学意义(F=3.21,P<0.05),三组之间两两比较,CC组血药浓度低于TT组,差异有统计学意义(P<0.05).三组剂量校正浓度分别为(304.84± 103.76)、(368.13± 143.49)、(444.50± 195.58),三组之间差异有统计学意义(F=4.19,P<0.05),三组之间两两比较,CC组血药浓度低于TT组,差异有统计学意义(P<0.05).三组HAMD减分率分别为0.42±0.11、0.46±0.11、0.52±0.09,三组之间差异有统计学意义(F=6.29,P<0.05),三组之间两两比较,CC组和CT组HAMD减分率均低于TT组,差异有统计学意义(均P<0.05).

  15. Evaluations of Zedoary Turmeric Oil on the Activity of Rat CYP1A2%莪术油对大鼠肝微粒体CYP1A2酶活性的影响

    Institute of Scientific and Technical Information of China (English)

    曹高忠; 郑仰明; 胡卢丰; 李军伟; 汤从容; 叶晓兰

    2011-01-01

    Objective: To develop an HPLC - MS determination method of phenaeetin and paracetamol and to investigate the effect of Zedoary Turmeric oil on the activity of rat CYP1 A2 for providing reference to rational drug use in clinic.Methods: Samples were separated on XDB- C 18 (150mm × 2. 1 mm,5μm) column, acetonitrile- 0. 1% formic acid was used as mobile phrase, and the flow rate was 0.4 mL · min-1 ,the column temperature was 30℃. The multiple reaction monitor was adopted to detect the concentration of phenacetin and paracetamol. Phenacetin was used as a probe of CYP1A2. The activity of rat CYP1 A2 was evaluated by an in - vitro experiment which two group involved, experiment group was given Zedoary Turmeric oil and the control group was given saline. Results: The calibration curves were linear in the ranges of 4 ~1600ng · mL-1( r =0.9973) phenacetin and 3 ~2000ng · mL-1( r =0.9973) paracetamol. The ratio of paracetamol/phenacetin in experiment group was 11.30 ± 0.71, the ratio of control group was 9.60 ± 1.04, pair T test was P < 0.05. Conclusion: The method is suitable for determination of phenacetin and paracetamol in rat liver microsomal incubation system. The activity of rat liver CYP1A2 can be enhanced by Zedoary Turmeric oil.%目的:建立非那西丁及其代谢产物的液质联用检测法,研究莪术油对大鼠肝微粒体CYP1A2酶活性的影响,为临床合理用药提供参考.方法:色谱柱为XDB-C18(150mm×2.1mm,5μm),流动相为乙腈-0.1%甲酸,流速:0.4mL·min(-1),柱温:30℃,以多反应监测方式采集数据.以非那西丁为探针药物,采用体外实验,实验组给予莪术油,对照组给予生理盐水,评价药物代谢酶CYP1A2酶活性的变化.结果:非那西丁和对乙酰氨基酚的检测浓度线性范围分别为4-1600ng·mL(-1)(r=0.9973)、3-2000ng·mL(-1)(r=0.9973).实验组测得的扑热息痛/非那西丁的比值:11.30±0.71,对照组:9.60±1.04,t检验显示P<0.05,有统计学意义.结论:本法

  16. Single nucleotide polymorphisms of CYP1A2 and their correlation with prostate cancer%CYP1A2基因多态性与前列腺癌的相关性研究

    Institute of Scientific and Technical Information of China (English)

    魏武; 葛京平; 董杰; 高建平; 张征宇; 龚隽

    2011-01-01

    目的:评价CYP1A2基因单核苷酸多态性(SNPs)与前列腺癌分期分级的相关性.方法:对253例良性前列腺增生(BPH)患者与206例去势前列腺癌患者CYP1A2基因中rs2069514-3859(A>G)位点及rs2069525-1707(C >T)位点进行基因测序,并对各基因表型与前列腺癌的分期分级相关性进行统计学分析.结果:BPH及去势前列腺癌患者的两种CYP1A2单核苷酸多态性的发生率无明显差异(P>0.05),其基因多态性与前列腺癌的病理分期均无相关性(P>0.05);但rs2069525-1707(C>T)中含C等位基因型的前列腺癌Gleason评分多在7分以下(P=0.030,OR=4.658,95% CI:1.222~17.754).结论:CYP1A2基因的SNPs与前列腺癌的病理分级之间可能有一定的相关性,但其发生机制及临床意义有待进一步证实及研究.%Objective: To evaluate the correlation of the single nucleotide polymorphisms (SNPs) of the CYP1A2 gene with the stages and grades of prostate cancer (PCa). Methods-, We conducted gene sequencing of the rs2069514-3859 ( A > G) and rs2069525-1707(C >T) alleles in the CYPIA2 gene in 253 patients with benign prostatic hyperplasia (BPH) and 206 patients with PCa treated by castration therapy, and statistically analyzed their correlations with the genotypes, stages and grades of prostate cancer. Results-. The incidences of the 2 CYP1A2 SNPs showed no significant difference between the BPH and the castrated PCa patients (P > 0.05 ) , and their genotypes were not correlated with the stages of PCa (P > 0.05 ). The Gleason scores were mostly T) allele (P =0.030, OR=4.658,95% CI: 1.222-17.754). Conclusion-. SNPs of the CYP1A2 gene may have some correlations with the pathologic stages of PCa, but their mechanisms and clinical significance need to be further confirmed. Natl J Androl, 2011, 17 (11) -. 998 -1001

  17. CYP1A2 phenotype and genotype in a population from the Carboniferous Region of Coahuila, Mexico.

    Science.gov (United States)

    Castorena-Torres, Fabiola; Mendoza-Cantú, Ania; de León, Mario Bermúdez; Cisneros, Bulmaro; Zapata-Pérez, Omar; López-Carrillo, Lizbeth; Salinas, Juan E; Albores, Arnulfo

    2005-04-28

    CYP1A2 regulation by polycyclic aromatic hydrocarbons (PAHs) exposure and polymorphism was investigated in 46 male volunteers from the Carboniferous Region in northern Coahuila, Mexico. PAH exposure was estimated by the urinary excretion of 1-hydroxypyrene (1-OHP), whereas the regulatory effects were assessed by the caffeine metabolic ratio (CMR). Genotype was evaluated by determining 5'-flanking region (-2964) and intron I (734) polymorphisms. A statistically significant difference in the urinary 1-OHP geometric means of Barroterán, Cloete and Juárez (2.30, 0.45 and 0.04, respectively) was observed. As for the genotype, the intron I distribution was 0% C/C, 46% C/A and 54% A/A, whereas that of the 5'-flanking region was 26% G/G, 42% G/A and 32% A/A. Both distributions were in agreement with the Hardy-Weinberg equilibrium model. A greater enzyme activity was observed in the A/A compared to C/A individuals according to the CMR (P<0.001), whereas the 5'-flanking region polymorphism showed no effect on CYP1A2 enzymatic activity. These results suggest that intron I polymorphism and PAH exposure are relevant factors that modulate CYP1A2 enzymatic activity.

  18. Genetic polymorphisms in promoter and intronic regions of CYP1A2 gene in Roma and Hungarian population samples.

    Science.gov (United States)

    Szalai, Renata; Magyari, Lili; Matyas, Petra; Duga, Balazs; Banfai, Zsolt; Szabo, Andras; Kovesdi, Erzsebet; Melegh, Bela

    2014-11-01

    The purpose of this study was to determine the interethnic differences of four CYP1A2 drug metabolizing enzyme variants. A total of 404 Roma and 396 Hungarian healthy subjects were genotyped for -163C>A, -729C>T, -2467delT and -3860G>A variants of CYP1A2 by RT-PCR and PCR-RFLP technique. The -3860A and -729T allele were not detectable in Roma samples, while in Hungarian samples were present with 2.02% and 0.25% prevalence, respectively. There was a 1.5-fold difference in presence of homozygous -163AA genotype between Hungarian and Roma samples (49.5% vs. 31.9%, pRomas (p=0.025). The -2467delT allele frequency was 6.81% in Roma group and 5.81% in Hungarians. The most frequent allelic constellation was -3860G/-2467T/-729C/-163A in both populations. In conclusion, Hungarians have markedly elevated chance for rapid metabolism of CYP1A2 substrates, intensified procarcinogen activation and increased risk for cancers.

  19. NADH:Cytochrome b5 Reductase and Cytochrome b5 Can Act as Sole Electron Donors to Human Cytochrome P450 1A1-Mediated Oxidation and DNA Adduct Formation by Benzo[a]pyrene.

    Science.gov (United States)

    Stiborová, Marie; Indra, Radek; Moserová, Michaela; Frei, Eva; Schmeiser, Heinz H; Kopka, Klaus; Philips, David H; Arlt, Volker M

    2016-08-15

    Benzo[a]pyrene (BaP) is a human carcinogen that covalently binds to DNA after activation by cytochrome P450 (P450). Here, we investigated whether NADH:cytochrome b5 reductase (CBR) in the presence of cytochrome b5 can act as sole electron donor to human P450 1A1 during BaP oxidation and replace the canonical NADPH:cytochrome P450 reductase (POR) system. We also studied the efficiencies of the coenzymes of these reductases, NADPH as a coenzyme of POR, and NADH as a coenzyme of CBR, to mediate BaP oxidation. Two systems containing human P450 1A1 were utilized: human recombinant P450 1A1 expressed with POR, CBR, epoxide hydrolase, and cytochrome b5 in Supersomes and human recombinant P450 1A1 reconstituted with POR and/or with CBR and cytochrome b5 in liposomes. BaP-9,10-dihydrodiol, BaP-7,8-dihydrodiol, BaP-1,6-dione, BaP-3,6-dione, BaP-9-ol, BaP-3-ol, a metabolite of unknown structure, and two BaP-DNA adducts were generated by the P450 1A1-Supersomes system, both in the presence of NADPH and in the presence of NADH. The major BaP-DNA adduct detected by (32)P-postlabeling was characterized as 10-(deoxyguanosin-N(2)-yl)-7,8,9-trihydroxy-7,8,9,10-tetrahydro-BaP (assigned adduct 1), while the minor adduct is probably a guanine adduct derived from 9-hydroxy-BaP-4,5-epoxide (assigned adduct 2). BaP-3-ol as the major metabolite, BaP-9-ol, BaP-1,6-dione, BaP-3,6-dione, an unknown metabolite, and adduct 2 were observed in the system using P450 1A1 reconstituted with POR plus NADPH. When P450 1A1 was reconstituted with CBR and cytochrome b5 plus NADH, BaP-3-ol was the predominant metabolite too, and an adduct 2 was also generated. Our results demonstrate that the NADH/cytochrome b5/CBR system can act as the sole electron donor both for the first and second reduction of P450 1A1 during the oxidation of BaP in vitro. They suggest that NADH-dependent CBR can replace NADPH-dependent POR in the P450 1A1-catalyzed metabolism of BaP.

  20. Evolution of insect P450.

    Science.gov (United States)

    Feyereisen, R

    2006-12-01

    The first fully sequenced insect genomes were those of the fruitfly and the mosquito, both from the order Diptera. Now, with an increasing number and diversity of insect genomes becoming available, the diversity of insect P450 genes can be better appreciated and tentative ideas about the evolution of the CYP (cytochrome P450) superfamily in insects can be proposed. There are four large clades of insect P450 genes that existed before the divergence of the class Insecta and that are also represented by CYP families in vertebrates: the CYP2 clade, the CYP3 clade, the CYP4 clade and the mitochondrial P450 clade. P450s with known or suspected physiological functions are present in each of these clades and only a dozen genes appear to have orthologues or very close paralogues in each insect genome. P450 enzymes from each of these clades have been linked to insecticide resistance or to the metabolism of natural products and xenobiotics. In particular, insects appear to maintain a repertoire of mitochondrial P450 paralogues devoted to the response to environmental challenges.

  1. Stabile Expression von Sulfotransferasen - allein oder in Kombination mit Cytochrom P450 - in Zelllinien für Mutagenitätsuntersuchungen

    Science.gov (United States)

    Pabel, Ulrike

    2003-10-01

    Aromatische Amine und Amide (aAA) sind aufgrund ihrer starken Verbreitung in der menschlichen Umwelt und ihres kanzerogenen Potenzials von groer toxikologischer Bedeutung. Die Kanzerogenität der aAA wird durch die Mutagenität hochreaktiver Stoffwechselprodukte vermittelt, die in zwei sequenziellen katalytischen Reaktionen entstehen. Die erste ist meistens eine N-Hydroxylierung, die oft durch Cytochrom P450 1A2 (CYP1A2) katalysiert wird. Daran schliet sich eine O-Konjugation durch Sulfotransferasen (SULT) oder N-Acetyltransferasen (NAT) an. Die Bioaktivierung ist ein kritischer Parameter für die Übertragbarkeit von Ergebnissen aus Tiermodellen auf den Menschen. Rekombinante in vitro Systeme, die fremdstoffmetabolisierende Enzyme verschiedener Spezies exprimieren, ermöglichen die vergleichende Untersuchung der Bioaktivierung im Menschen und in Versuchstieren. Ziel des Projektes war die Aufklärung der Bioaktivierung der aAA durch humane Enzyme. Im Vordergrund stand die Untersuchung der Rolle humaner SULT in diesem Prozess. Es wurden rekombinante in vitro Systeme, konstruiert, die CYP1A2 und SULT des Menschen koexprimieren. SULT-cDNAs wurden in den Säugerzell Expressionsvektor pMPSV kloniert und in Standardindikatorzellen für Mutagenitätsuntersuchungen (V79 Zellen aus dem Chinesischen Hamster) transfiziert. Das Expressionsniveau von CYP1A2 und SULT wurde mittels Immunblotanalyse und radiometrischen Aktivitätsmessungen charakterisiert. In den rekombinanten Zellen wurden vier aAA als Modellsubstanzen (2-Acetylaminofluoren, 2-Aminoanthracen, 3′-Methyl-4-dimethylaminoazobenzol, 2,4-Diaminotoluol) auf ihre Mutagenität am hprt-Locus hin untersucht.Die aAA waren in Zellen, die keine rekombinanten Enzyme oder lediglich CYP1A2 exprimierten, nicht mutagen. In Zellen, die CYP1A2 und SULT der Subfamilie 1A koexprimierten, erzeugten sie bereits in geringen Konzentrationen klare mutagene Effekte (0,3 µM für 2-Acetylaminofluoren und 3′-Methyl-4-dimethylaminoazobenzol

  2. Role of specific cytochrome P450 isoforms in the conversion of phenoxypropoxybiguanide analogs in human liver microsomes to potent antimalarial dihydrotriazines.

    Science.gov (United States)

    Diaz, Damaris S; Kozar, Michael P; Smith, Kirsten S; Asher, Constance O; Sousa, Jason C; Schiehser, Guy A; Jacobus, David P; Milhous, Wilbur K; Skillman, Donald R; Shearer, Todd W

    2008-02-01

    Phenoxypropoxybiguanides, such as PS-15, are antimalarial prodrugs analogous to the relationship of proguanil and its active metabolite cycloguanil. Unlike cycloguanil, however, WR99210, the active metabolite of PS-15, has retained in vitro potency against newly emerging antifolate-resistant malaria parasites. Recently, in vitro metabolism of a new series of phenoxypropoxybiguanide analogs has examined the production of the active triazine metabolites by human liver microsomes. The purpose of this investigation was to elucidate the primary cytochrome P450 isoforms involved in the production of active metabolites in the current lead candidate. By using expressed human recombinant isoform preparations, specific chemical inhibitors, and isoform-specific inhibitory antibodies, the primary cytochrome P450 isoforms involved in the in vitro metabolic activation of JPC-2056 were elucidated. Unlike proguanil, which is metabolized primarily by CYP2C19, the results indicate that CYP3A4 plays a more important role in the metabolism of both PS-15 and JPC-2056. Whereas CYP2D6 appears to play a major role in the metabolism of PS-15 to WR99210, it appears less important in the conversion of JPC-2056 to JPC-2067. These results are encouraging, considering the prominence of CYP2C19 and CYP2D6 polymorphisms in certain populations at risk for contracting malaria, because the current clinical prodrug candidate from this series may be less dependent on these enzymes for metabolic activation.

  3. Inhibition of cytochrome P450 1A2-mediated metabolism and production of reactive oxygen species by heme oxygenase-1 in rat liver microsomes.

    Science.gov (United States)

    Reed, James R; Cawley, George F; Backes, Wayne L

    2011-01-01

    Heme oxygenase-1 (HO-1) is induced in most cell types by many forms of environmental stress and is believed to play a protective role in cells exposed to oxidative stress. Metabolism by cytochromes P450 (P450) is highly inefficient as the oxidation of substrate is associated with the production of varying proportions of hydrogen peroxide and/or superoxide. This study tests the hypothesis that heme oxygenase-1 (HO-1) plays a protective role against oxidative stress by competing with P450 for binding to the common redox partner, the NADPH P450 reductase (CPR) and in the process, diminishing P450 metabolism and the associated production of reactive oxygen species (ROS). Liver microsomes were isolated from uninduced rats and rats that were treated with cadmium and/or β-napthoflavone (BNF) to induce HO-1 and/or CYP1A2. HO-1 induction was associated with slower rates of metabolism of the CYP1A2-specific substrate, 7-ethoxyresorufin. Furthermore, HO-1 induction also was associated with slower rates of hydrogen peroxide and hydroxyl radical production by microsomes from rats induced for CYP1A2. The inhibition associated with HO-1 induction was not dependent on the addition of heme to the microsomal incubations. The effects of HO-1 induction were less dramatic in the absence of substrate for CYP1A2, suggesting that the enzyme was more effective in inhibiting the CYP1A2-related activity than the CPR-related production of superoxide (that dismutates to form hydrogen peroxide).

  4. Characterization of the Ala62Pro polymorphic variant of human cytochrome P450 1A1 using recombinant protein expression

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Seung Heon; Kang, Sukmo [College of Veterinary Medicine, BK21plus Program for Creative Veterinary Science Research, and Research Institute for Veterinary Science, Seoul National University, Seoul (Korea, Republic of); Dong, Mi Sook [School of Life Sciences and Biotechnology, Korea University, Seoul (Korea, Republic of); Park, Jung-Duck [College of Medicine, Chung-Ang University, Seoul (Korea, Republic of); Park, Jinseo; Rhee, Sangkee [College of Agriculture of Life Science, Seoul National University, Seoul (Korea, Republic of); Ryu, Doug-Young, E-mail: dyryu@snu.ac.kr [College of Veterinary Medicine, BK21plus Program for Creative Veterinary Science Research, and Research Institute for Veterinary Science, Seoul National University, Seoul (Korea, Republic of)

    2015-06-15

    Cytochrome P450 (CYP) 1A1 is a heme-containing enzyme involved in detoxification of hydrophobic pollutants. Its Ala62Pro variant has been identified previously. Ala62 is located in α-helix A of CYP1A1. Residues such as Pro and Gly are α-helix breakers. In this study, the Ala62Pro variant was characterized using heterologous expression. E. coli expressing the Ala62Pro variant, and the purified variant protein, had lower CYP (i.e. holoenzyme) contents than their wild-type (WT) equivalents. The CYP variant from E. coli and mammalian cells exhibited lower 7-ethoxyresorufin O-dealkylation (EROD) and benzo[a]pyrene hydroxylation activities than the WT. Enhanced supplementation of a heme precursor during E. coli culture did not increase CYP content in E. coli expressing the variant, but did for the WT. As for Ala62Pro, E. coli expressing an Ala62Gly variant had a lower CYP content than the WT counterpart, but substitution of Ala62 with α-helix-compatible residues such as Ser and Val partially recovered the level of CYP produced. Microsomes from mammalian cells expressing Ala62Pro and Ala62Gly variants exhibited lower EROD activities than those expressing the WT or Ala62Val variant. A region harboring α-helix A has interactions with another region containing heme-interacting residues. Site-directed mutagenesis analyses suggest the importance of interactions between the two regions on holoenzyme expression. Together, these findings suggest that the Ala62Pro substitution leads to changes in protein characteristics and function of CYP1A1 via structural disturbance of the region where the residue is located. - Highlights: • Ala62 is located in α-helix A of the carcinogen-metabolizing enzyme CYP1A1. • Pro acts as an α-helix breaker. • A variant protein of CYP1A1, Ala62Pro, had lower heme content than the wild-type. • The variant of CYP1A1 had lower enzyme activities than the wild-type.

  5. Distribution of cytochrome P450 2C, 2E1, 3A4, and 3A5 in human colon mucosa

    DEFF Research Database (Denmark)

    Parlesak, Alexandr

    2005-01-01

    BACKGROUND: Despite the fact that the alimentary tract is part of the body's first line of defense against orally ingested xenobiotica, little is known about the distribution and expression of cytochrome P450 (CYP) enzymes in human colon. Therefore, expression and protein levels of four...... representative CYPs (CYP2C(8), CYP2E1, CYP3A4, and CYP3A5) were determined in human colon mucosa biopsies obtained from ascending, descending and sigmoid colon. METHODS: Expression of CYP2C, CYP2E1, CYP3A4, and CYP3A5 mRNA in colon mucosa was determined by RT-PCR. Protein concentration of CYPs was determined...... to the descending colon. CONCLUSION: The current data suggest that the expression of CYP2C, CYP2E1, and CYP3A5 varies in different parts of the colon....

  6. Exon-specific northern analysis and rapid amplification of cDNA ends (RACE) reveal that the proximal promoter II (PII) is responsible for aromatase cytochrome P450 (CYP19) expression in human ovary.

    Science.gov (United States)

    Jenkins, C; Michael, D; Mahendroo, M; Simpson, E

    1993-11-01

    Estrogens are synthesized from C19 steroids by a unique form of cytochrome P450, aromatase cytochrome P-450 (P-450AROM; the product of the CYP19 gene). We have shown that tissue-specific expression of human P-450AROM is determined, in part, by the use of alternative promoters. Previous methods of analysis for determining the specific 5'-termini of the different transcripts included S1 nuclease protection, primer extension, and Northern analysis. In the present study we have used the RACE procedure (rapid amplification of cDNA ends) to amplify and clone the 5' termini of P-450AROM transcripts expressed in human corpus luteum (CL). Sequencing of the resulting clones supports the results of the previously performed studies. Specifically, the proximal promoter, PII, is the predominant promoter utilized in CL, such that the start of transcription occurs 26 bp downstream of the putative TATA sequence. A minority of the clones possess an alternative 5'-end, namely I.3. Exon-specific Northern analysis confirms that the majority of the P-450AROM transcripts in CL tissue contain sequence specific for promoter II. Similarly, exon-specific Northern analysis indicates that transcripts in human follicles, as well as granulosa cells in culture, contain primarily sequence specific for promoter II.

  7. In vitro cytochrome P450 inhibition potential of methylenedioxy-derived designer drugs studied with a two-cocktail approach.

    Science.gov (United States)

    Dinger, Julia; Meyer, Markus R; Maurer, Hans H

    2016-02-01

    In vitro cytochrome P450 (CYP) inhibition assays are common approaches for testing the inhibition potential of drugs for predicting potential interactions. In contrast to marketed medicaments, drugs of abuse, particularly the so-called novel psychoactive substances, were not tested before distribution and consumption. Therefore, the inhibition potential of methylenedioxy-derived designer drugs (MDD) of different drug classes such as aminoindanes, amphetamines, benzofurans, cathinones, piperazines, pyrrolidinophenones, and tryptamines should be elucidated. The FDA-preferred test substrates, split in two cocktails, were incubated with pooled human liver microsomes and analysed after protein precipitation using LC-high-resolution-MS/MS. IC50 values were determined of MDD showing more than 50 % inhibition in the prescreening. Values were calculated by plotting the relative metabolite concentration formed over the logarithm of the inhibitor concentration. All MDD showed inhibition against CYP2D6 activity and most of them in the range of the clinically relevant CYP2D6 inhibitors quinidine and fluoxetine. In addition, the beta-keto compounds showed inhibition of the activity of CYP2B6, 5,6-MD-DALT of CYP1A2 and CYP3A, and MDAI of CYP2A6, all in the range of clinically relevant inhibitors. In summary, all MDD showed inhibition of the activity of CYP2D6, six of CYP1A2, three of CYP2A6, 13 of CYP2B6, two of CYP2C9, six of CYP2C19, one of CYP2E1, and six of CYP3A. These results showed that the CYP inhibition by MDD might be clinically relevant, but further studies are needed for final conclusions.

  8. Cytochrome P450 enzymes involved in the metabolic pathway of the histamine 2 (H2)-receptor antagonist roxatidine acetate by human liver microsomes.

    Science.gov (United States)

    Sasaki, M; Nakayama, M; Numazawa, S; Oguro, T; Honma, S; Iwamura, S; Tsukamoto, K; Yoshida, T

    2001-01-01

    Roxatidine acetate hydrochloride (ROX, 2-acetoxy-N-[3-[m-(1-piperidinylmethyl)phenoxy]propyl]acetamide hydrochloride, CAS 78273-80-0), a histamine 2 (H2)-receptor antagonist, has been clinically applied for the treatment of gastritis, gastric and duodenal ulcers. There is no report on the identification of the metabolic enzyme of M-1 (2-hydroxy-N-[3-[m-(1-piperidinylmethyl)phenoxy]propyl]acetamide), the pharmacologically active metabolite, in humans. In this study, the Cytochrome P450 (CYP or P450) enzymes which participate in the metabolism of ROX were identified using human liver microsomes and S9 fractions. M-1 was converted to M-4 (3-[m-(1-piperidinyl-methyl)phenoxy]propylamine) by the enzyme reaction with the S9 but not with microsomes. M-4 was further metabolized to M-5 (3-[m-(1-piperidinylmethyl)phenoxy]propanol) by microsomes. The metabolism was inhibited by coumarin and anti-CYP2A1 serum. (3-[m-(1-piperidinylmethyl)-phenoxy]propionic acid) and M-3 (m-(1-piperidinylmethyl) phenol) formation from M-5 were inhibited by quinidine and anti-CYP2D6 serum. Moreover, M-5 was converted to M-2 and M-3 by cDNA-expressed CYP2D6. In conclusion, this study shows that microsomal enzymes do not participate in the clearance of the active metabolite M-1, CYP2A6 primarily catalyzes M-5 formation from M-4, and CYP2D6 primarily catalyzes M-2 and M-3 formation from M-5 in humans.

  9. Structures of Human Cyctochrome P450 2E1: Insights Into the Binding of Inhibitors And Both Small Molecular Weight And Fatty Acid Substrates

    Energy Technology Data Exchange (ETDEWEB)

    Porubsky, P.R.; Meneely, K.M.; Scott, E.E.

    2009-05-21

    Human microsomal cytochrome P-450 2E1 (CYP2E1) monooxygenates >70 low molecular weight xenobiotic compounds, as well as much larger endogenous fatty acid signaling molecules such as arachidonic acid. In the process, CYP2E1 can generate toxic or carcinogenic compounds, as occurs with acetaminophen overdose, nitrosamines in cigarette smoke, and reactive oxygen species from uncoupled catalysis. Thus, the diverse roles that CYP2E1 has in normal physiology, toxicity, and drug metabolism are related to its ability to metabolize diverse classes of ligands, but the structural basis for this was previously unknown. Structures of human CYP2E1 have been solved to 2.2 {angstrom} for an indazole complex and 2.6 {angstrom} for a 4-methylpyrazole complex. Both inhibitors bind to the heme iron and hydrogen bond to Thr{sup 303} within the active site. Complementing its small molecular weight substrates, the hydrophobic CYP2E1 active site is the smallest yet observed for a human cytochrome P-450. The CYP2E1 active site also has two adjacent voids: one enclosed above the I helix and the other forming a channel to the protein surface. Minor repositioning of the Phe{sup 478} aromatic ring that separates the active site and access channel would allow the carboxylate of fatty acid substrates to interact with conserved {sup 216}QXXNN{sup 220} residues in the access channel while positioning the hydrocarbon terminus in the active site, consistent with experimentally observed {omega}-1 hydroxylation of saturated fatty acids. Thus, these structures provide insights into the ability of CYP2E1 to effectively bind and metabolize both small molecule substrates and fatty acids.

  10. CYP1A2 Genotype Variations Do Not Modify the Benefits and Drawbacks of Caffeine during Exercise: A Pilot Study

    Science.gov (United States)

    Salinero, Juan J.; Lara, Beatriz; Ruiz-Vicente, Diana; Areces, Francisco; Puente-Torres, Carlos; Gallo-Salazar, César; Pascual, Teodoro; Del Coso, Juan

    2017-01-01

    Previous investigations have determined that some individuals have minimal or even ergolytic performance effects after caffeine ingestion. The aim of this study was to analyze the influence of the genetic variations of the CYP1A2 gene on the performance enhancement effects of ingesting a moderate dose of caffeine. In a double-blind randomized experimental design, 21 healthy active participants (29.3 ± 7.7 years) ingested 3 mg of caffeine per kg of body mass or a placebo in testing sessions separated by one week. Performance in the 30 s Wingate test, visual attention, and side effects were evaluated. DNA was obtained from whole blood samples and the CYP1A2 polymorphism was analyzed (rs762551). We obtained two groups: AA homozygotes (n = 5) and C-allele carriers (n = 16). Caffeine ingestion increased peak power (682 ± 140 vs. 667 ± 137 W; p = 0.008) and mean power during the Wingate test (527 ± 111 vs. 518 ± 111 W; p 0.05). Reaction times were similar between caffeine and placebo conditions (276 ± 31 vs. 269 ± 71 milliseconds; p = 0.681) with no differences between AA homozygotes and C-allele carriers. However, 31.3% of the C-allele carriers reported increased nervousness after caffeine ingestion, while none of the AA homozygotes perceived this side effect. Genetic variations of the CYP1A2 polymorphism did not affect the ergogenic effects and drawbacks derived from the ingestion of a moderate dose of caffeine. PMID:28287486

  11. CYP1A2 Genotype Variations Do Not Modify the Benefits and Drawbacks of Caffeine during Exercise: A Pilot Study.

    Science.gov (United States)

    Salinero, Juan J; Lara, Beatriz; Ruiz-Vicente, Diana; Areces, Francisco; Puente-Torres, Carlos; Gallo-Salazar, César; Pascual, Teodoro; Del Coso, Juan

    2017-03-11

    Previous investigations have determined that some individuals have minimal or even ergolytic performance effects after caffeine ingestion. The aim of this study was to analyze the influence of the genetic variations of the CYP1A2 gene on the performance enhancement effects of ingesting a moderate dose of caffeine. In a double-blind randomized experimental design, 21 healthy active participants (29.3 ± 7.7 years) ingested 3 mg of caffeine per kg of body mass or a placebo in testing sessions separated by one week. Performance in the 30 s Wingate test, visual attention, and side effects were evaluated. DNA was obtained from whole blood samples and the CYP1A2 polymorphism was analyzed (rs762551). We obtained two groups: AA homozygotes (n = 5) and C-allele carriers (n = 16). Caffeine ingestion increased peak power (682 ± 140 vs. 667 ± 137 W; p = 0.008) and mean power during the Wingate test (527 ± 111 vs. 518 ± 111 W; p 0.05). Reaction times were similar between caffeine and placebo conditions (276 ± 31 vs. 269 ± 71 milliseconds; p = 0.681) with no differences between AA homozygotes and C-allele carriers. However, 31.3% of the C-allele carriers reported increased nervousness after caffeine ingestion, while none of the AA homozygotes perceived this side effect. Genetic variations of the CYP1A2 polymorphism did not affect the ergogenic effects and drawbacks derived from the ingestion of a moderate dose of caffeine.

  12. Effects of Tibetan Medicine Zuotai on the Activities of CYP1A2 and NAT2 in Rats%藏药佐太对大鼠CYP1A2和NAT2活性的影响

    Institute of Scientific and Technical Information of China (English)

    范雪汝; 朱俊博; 姚星辰; 袁明; 李向阳

    2015-01-01

    目的:研究藏药佐太对大鼠细胞色素氧化酶(CYP1A2)、药物代谢酶N-乙酰基转移酶2(NAT2)活性的影响。方法:将70只SD大鼠随机均分为正常对照(生理盐水)组和佐太低、中、高剂量(1.2、3.8、12 mg/kg)单次给药组和多次给药组(每天1次,连续12 d),分别ig给药。正常对照组、佐太单次给药组于第2天,佐太多次给药组于第13天分别ig给予咖啡因(25 mg/kg),5 h后采集尿液,按10 mg/ml加入维生素C。采用高效液相色谱法测定大鼠尿液中咖啡因代谢物5-乙酰氨基-6-甲酰氨基-3-甲基尿酸(AFMU)、1-甲基黄嘌呤(1X)、1-甲基尿酸(1U)、1,7-二甲基尿酸(17U)的含量,以(AFMU+1X+1U)/17U、AFMU/(AFMU+1X+1U)比值来反映CYP1A2和NAT2活性。结果:与正常对照组比较,佐太中剂量单次给药组及多次给药组、高剂量多次给药组大鼠(AFMU+1X+1U)/17U、AFMU/(AFMU+1X+1U)比值降低,即CYP1A2和NAT2活性降低,差异有统计学意义(P<0.05)。结论:佐太对大鼠CYP1A2和NAT2活性有明显抑制作用。%OBJECTIVE:To study the effects of Tibetan medicine Zuotai on the activities of cytochrome oxidase (CYP1A2) and drug metabolism enzyme N-acetyltransferase 2(NAT2)in rats. METHODS:70 SD rats were equally randomized into a normal control (normal saline) group,the groups of single administration of low,middle and high-dose (1.2,3.8 and 12 mg/kg) Zuotai and the groups of multiple administrations thereof(once daily for 12 consecutive days). The rats were given drugs ig. caffeine(25 mg/kg)was given ig to the rats in the normal control group and the groups of single administration on the 2nd day,and to those in the groups of multiple administrations on the 13th day. 5 h later,their urine was collected and added with vitamin C based on 10 mg/ml. High performance liquid chromatography (HPLC) was adopted to determine the cafeine metabolites contents of 5

  13. 高效液相色谱法测定鼠肝微粒体中CYP1A2酶的活性及动力学考察%HPLC determination of activity of CYP1A2 and its pharmacokinetics in rat liver microsomes

    Institute of Scientific and Technical Information of China (English)

    张艳辉; 于超; 郭延垒; 张有金; 杨竹; 王应雄

    2012-01-01

    Objective:To establish a method evaluates cytochrome p450 1A2 (CYP1A2) activity using phenacetin as a probe by high - performance liquid chromatography ( HPLC) - UV detection. Methods: Column for the Shi-madzu Shim - Pack VP - ODS (150 mm 4. 6 mm,5μm) and mobile phase of 100 mmol ? L~-1phosphate buffer (pH 4. 3) - acetonitrile were used. Detection wavelength was 245 nm. Phenacetin was incubated with rat liver mi-crosomes at 37 ℃ for 60 min and the reaction was stopped by cold methanol. The reactive liquid was centrifuged at 12000 r min-1 for 10 min. Finally,the supernatant was analyzed by HPLC. Results:Phenacetin,acetamidophenol and 3 - acetamidophenol were perfectly separated. The detection limit of phenacetin was 50 nmol L-1 and the linear range of method was 0. 1μmol ? L-1 to 10 μmol · L-1. The intraday and interday relative standard deviations were less than 10% respectively. The method recoveries were more than 75%. The methanol was selected as reagent to terminate the reaction catalyzed by CYP1A2 and the incubation time was 60 min. The kinetic parameters was shown that Vmax was 0. 21 nmol · min-1 · mg protein-1 and Km was 20. 39 μmol · L-1. Conclusions;The method is stead-y,accurate and suitable for assaying CYP1A2 activity which can be used to evaluate the pharmacokinetics of CYP1A2 in rat liver microsomes.%目的:建立以非那西丁为探针的高效液相色谱-紫外检测的实验方法,测定大鼠肝微粒体中CYP1 A2酶活性并对其进行动力学考察.方法:采用Shimadzu Shim - Pack VP - ODS柱(150 mm×4.6 mm,5μm),流动相为:100 mmol · L-1磷酸二氢钠缓冲液(pH 4.3)和乙腈,梯度洗脱,流速为1.0 mL·min-1,柱温为室温,检测波长245 nm.非那西丁与大鼠肝微粒体在37℃温孵60 min,加入冰甲醇终止,12000 r·min-1离心10 min,取上清进行HPLC分析,以Lineweaver - Burk作图计算Vmax与Km值.结果:非那西丁、对乙酰氨基酚及其内标间乙酰氨基酚三者分离良好且无内源性干

  14. Induction of digitoxigenin monodigitoxoside UDP-glucuronosyltransferase activity by glucocorticoids and other inducers of cytochrome P-450p in primary monolayer cultures of adult rat hepatocytes and in human liver.

    Science.gov (United States)

    Schuetz, E G; Hazelton, G A; Hall, J; Watkins, P B; Klaassen, C D; Guzelian, P S

    1986-06-25

    We have recently proposed that glucocorticoids induce cytochrome P-450p, a liver microsomal hemoprotein originally isolated from rats treated with the antiglucocorticoid pregnenolone 16 alpha-carbonitrile (PCN), through a mechanism that involves a stereospecific recognition system clearly distinguishable from the classic glucocorticoid receptor (Schuetz, E. G., Wrighton, S. A., Barwick, J. L., and Guzelian, P. S. (1984) J. Biol. Chem. 259, 1999-2012). We now report that digitoxigenin monodigitoxoside UDP-glucuronosyltransferase (DIG UDP-glucuronosyltransferase), a liver microsomal enzyme activity induced by PCN in rats, is also inducible, as is P-450p, in primary monolayer cultures of adult rat hepatocytes. DIG UDP-glucuronosyltransferase activity closely resembled reported characteristics of induction of P-450p in its time course of induction, concentration-response relationships, exclusivity of induction by steroids with glucocorticoid properties, unusual rank order of potency of glucocorticoid agonists, unusually high ED50 for induction by glucocorticoids, enhanced induction rather than inhibition by anti-glucocorticoids in the presence of glucocorticoids, and finally, induction by nonsteroidal inducers of P-450p. DIG UDP-glucuronosyltransferase activity was also readily detected in human liver microsomes and was elevated in two patients who had received inducers of P-450p. We conclude that the liver enzymes controlled by the postulated PCN recognition system include not only P-450p but also one or more UDP-glucuronosyltransferases.

  15. In vitro metabolic clearance of pyrethroid pesticides by rat and human hepatic microsomes and cytochrome P450 isoforms

    Science.gov (United States)

    Species differences in the intrinsic clearance (CLint) and the enzymes involved in the metabolism of pyrethroid pesticides were examined in rat and human hepatic microsomes. The pyrethroids bifenthrin, S-bioallethrin, bioresmethrin, β-cyfluthrin, cypermethrin, cis-per...

  16. Engineering cytochrome p450 enzymes.

    Science.gov (United States)

    Gillam, Elizabeth M J

    2008-01-01

    The last 20 years have seen the widespread and routine application of methods in molecular biology such as molecular cloning, recombinant protein expression, and the polymerase chain reaction. This has had implications not only for the study of toxicological mechanisms but also for the exploitation of enzymes involved in xenobiotic clearance. The engineering of P450s has been performed with several purposes. The first and most fundamental has been to enable successful recombinant expression in host systems such as bacteria. This in turn has led to efforts to solubilize the proteins as a prerequisite to crystallization and structure determination. Lagging behind has been the engineering of enzyme activity, hampered in part by our still-meager comprehension of fundamental structure-function relationships in P450s. However, the emerging technique of directed evolution holds promise in delivering both engineered enzymes for use in biocatalysis and incidental improvements in our understanding of sequence-structure and sequence-function relationships, provided that data mining can extract the fundamental correlations underpinning the data. From the very first studies on recombinant P450s, efforts were directed toward constructing fusions between P450s and redox partners in the hope of generating more efficient enzymes. While this aim has been allowed to lie fallow for some time, this area merits further investigation as does the development of surface-displayed P450 systems for biocatalytic and biosensor applications. The final application of engineered P450s will require other aspects of their biology to be addressed, such as tolerance to heat, solvents, and high substrate and product concentrations. The most important application of these enzymes in toxicology in the near future is likely to be the biocatalytic generation of drug metabolites for the pharmaceutical industry. Further tailoring will be necessary for specific toxicological applications, such as in

  17. The Effects of Acute Hydrogen Sulfide Poisoning on Cytochrome P450 Isoforms Activity in Rats

    OpenAIRE

    Xianqin Wang; Mengchun Chen; Xinxin Chen; Jianshe Ma; Congcong Wen; Jianchun Pan; Lufeng Hu; Guanyang Lin

    2014-01-01

    Hydrogen sulfide (H2S) is the second leading cause of toxin related death (after carbon monoxide) in the workplace. H2S is absorbed by the upper respiratory tract mucosa, and it causes histotoxic hypoxemia and respiratory depression. Cocktail method was used to evaluate the influences of acute H2S poisoning on the activities of cytochrome P450 isoforms CYP2B6, CYP2D6, CYP3A4, CYP1A2, CYP2C19, and CYP2C9, which were reflected by the changes of pharmacokinetic parameters of six specific probe d...

  18. Cytochromes P450 are Expressed in Proliferating Cells in Barrett's Metaplasia

    OpenAIRE

    Hughes, Steven J.; Morse, Mark A.; Weghorst, Christopher M.; Hyesook Kim; Watkins, Paul B.; Peter Guengerich, F.; Orringer, Mark B.; Beer, David G.

    1999-01-01

    The expression of cytochromes P450 (CYP) in Barrett's esophagus and esophageal squamous mucosa was investigated. Esophagectomy specimens from 23 patients were examined for CYP expression of CYP1A2, CYP3A4, CYP2C9/10, and CYP2E1 by immunohistochemical analysis, and the expression of CYP1A1, CYP3A4, CYP1B1, CYP2E1, and CYP2C9/10 in these tissues was further confirmed by reverse transcription polymerase chain reaction. Immunohistochemical analysis of esophageal squamous mucosa (n = 12) showed ex...

  19. Clinical Exposure Boost Predictions by Integrating Cytochrome P450 3A4-Humanized Mouse Studies With PBPK Modeling.

    Science.gov (United States)

    Zhang, Jin; Heimbach, Tycho; Scheer, Nico; Barve, Avantika; Li, Wenkui; Lin, Wen; He, Handan

    2016-04-01

    NVS123 is a poorly water-soluble protease 56 inhibitor in clinical development. Data from in vitro hepatocyte studies suggested that NVS123 is mainly metabolized by CYP3A4. As a consequence of limited solubility, NVS123 therapeutic plasma exposures could not be achieved even with high doses and optimized formulations. One approach to overcome NVS123 developability issues was to increase plasma exposure by coadministrating it with an inhibitor of CYP3A4 such as ritonavir. A clinical boost effect was predicted by using physiologically based pharmacokinetic (PBPK) modeling. However, initial boost predictions lacked sufficient confidence because a key parameter, fraction of drug metabolized by CYP3A4 (fmCYP3A4), could not be estimated with accuracy on account of disconnects between in vitro and in vivo preclinical data. To accurately estimate fmCYP3A4 in human, an in vivo boost effect study was conducted using CYP3A4-humanized mouse model which showed a 33- to 56-fold exposure boost effect. Using a top-down approach, human fmCYP3A4 for NVS123 was estimated to be very high and included in the human PBPK modeling to support subsequent clinical study design. The combined use of the in vivo boost study in CYP3A4-humanized mouse model mice along with PBPK modeling accurately predicted the clinical outcome and identified a significant NVS123 exposure boost (∼42-fold increase) with ritonavir.

  20. Recombinant Saccharomyces cerevisiae expressing P450 in artificial digestive systems : A model for biodetoxication in the human digestive environment

    NARCIS (Netherlands)

    Blanquet, S.; Meunier, J.P.; Minekus, M.; Marol-Bonnin, S.; Alric, M.

    2003-01-01

    The use of genetically engineered microorganisms such as bacteria or yeasts as live vehicles to carry out bioconversion directly in the digestive environment is an important challenge for the development of innovative biodrugs. A system that mimics the human gastrointestinal tract was combined with

  1. Recombinant Saccharomyces cerevisiae expressing P450 in artificial digestive systems : A model for biodetoxication in the human digestive environment

    NARCIS (Netherlands)

    Blanquet, S.; Meunier, J.P.; Minekus, M.; Marol-Bonnin, S.; Alric, M.

    2003-01-01

    The use of genetically engineered microorganisms such as bacteria or yeasts as live vehicles to carry out bioconversion directly in the digestive environment is an important challenge for the development of innovative biodrugs. A system that mimics the human gastrointestinal tract was combined with

  2. Genome-wide meta-analysis identifies regions on 7p21 (AHR and 15q24 (CYP1A2 as determinants of habitual caffeine consumption.

    Directory of Open Access Journals (Sweden)

    Marilyn C Cornelis

    2011-04-01

    Full Text Available We report the first genome-wide association study of habitual caffeine intake. We included 47,341 individuals of European descent based on five population-based studies within the United States. In a meta-analysis adjusted for age, sex, smoking, and eigenvectors of population variation, two loci achieved genome-wide significance: 7p21 (P = 2.4 × 10(-19, near AHR, and 15q24 (P = 5.2 × 10(-14, between CYP1A1 and CYP1A2. Both the AHR and CYP1A2 genes are biologically plausible candidates as CYP1A2 metabolizes caffeine and AHR regulates CYP1A2.

  3. Mammalian Cytochrome P450-Dependent Metabolism of Polychlorinated Dibenzo-p-dioxins and Coplanar Polychlorinated Biphenyls

    Directory of Open Access Journals (Sweden)

    Hideyuki Inui

    2014-08-01

    Full Text Available Polychlorinated dibenzo-p-dioxins (PCDDs and coplanar polychlorinated biphenyls (PCBs contribute to dioxin toxicity in humans and wildlife after bioaccumulation through the food chain from the environment. The authors examined human and rat cytochrome P450 (CYP-dependent metabolism of PCDDs and PCBs. A number of human CYP isoforms belonging to the CYP1 and CYP2 families showed remarkable activities toward low-chlorinated PCDDs. In particular, human CYP1A1, CYP1A2, and CYP1B1 showed high activities toward monoCDDs, diCDDs, and triCDDs but no detectable activity toward 2,3,7,8-tetrachlorodibenzo-p-dioxin (2,3,7,8-tetraCDD. Large amino acids located at putative substrate-recognition sites and the F-G loop in rat CYP1A1 contributed to the successful metabolism of 2,3,7,8-tetraCDD. Rat, but not human, CYP1A1 metabolized 3,3',4,4',5-pentachlorobiphenyl (CB126 to two hydroxylated metabolites. These metabolites are probably less toxic than is CB126, due to their higher solubility. Homology models of human and rat CYP1A1s and CB126 docking studies indicated that two amino acid differences in the CB126-binding cavity were important for CB126 metabolism. In this review, the importance of CYPs in the metabolism of dioxins and PCBs in mammals and the species-based differences between humans and rats are described. In addition, the authors reveal the molecular mechanism behind the binding modes of dioxins and PCBs in the heme pocket of CYPs.

  4. Mammalian cytochrome P450-dependent metabolism of polychlorinated dibenzo-p-dioxins and coplanar polychlorinated biphenyls.

    Science.gov (United States)

    Inui, Hideyuki; Itoh, Toshimasa; Yamamoto, Keiko; Ikushiro, Shin-Ichi; Sakaki, Toshiyuki

    2014-08-13

    Polychlorinated dibenzo-p-dioxins (PCDDs) and coplanar polychlorinated biphenyls (PCBs) contribute to dioxin toxicity in humans and wildlife after bioaccumulation through the food chain from the environment. The authors examined human and rat cytochrome P450 (CYP)-dependent metabolism of PCDDs and PCBs. A number of human CYP isoforms belonging to the CYP1 and CYP2 families showed remarkable activities toward low-chlorinated PCDDs. In particular, human CYP1A1, CYP1A2, and CYP1B1 showed high activities toward monoCDDs, diCDDs, and triCDDs but no detectable activity toward 2,3,7,8-tetrachlorodibenzo-p-dioxin (2,3,7,8-tetraCDD). Large amino acids located at putative substrate-recognition sites and the F-G loop in rat CYP1A1 contributed to the successful metabolism of 2,3,7,8-tetraCDD. Rat, but not human, CYP1A1 metabolized 3,3',4,4',5-pentachlorobiphenyl (CB126) to two hydroxylated metabolites. These metabolites are probably less toxic than is CB126, due to their higher solubility. Homology models of human and rat CYP1A1s and CB126 docking studies indicated that two amino acid differences in the CB126-binding cavity were important for CB126 metabolism. In this review, the importance of CYPs in the metabolism of dioxins and PCBs in mammals and the species-based differences between humans and rats are described. In addition, the authors reveal the molecular mechanism behind the binding modes of dioxins and PCBs in the heme pocket of CYPs.

  5. Cytochrome P450 1B1, a novel chemopreventive target for benzo[a]pyrene-initiated human esophageal cancer.

    OpenAIRE

    Wen, Xia; Walle, Thomas

    2007-01-01

    Dietary modulation of carcinogenesis-related pathwaysDietary item or component studied: 5,7- dimethoxyflavone (5,7-DMF) and 30,40-dimethoxyflavone (30,40-DMF)Pathways studied: BaP- DNA binding by inhibition of CYP1B1/1A1 activity and/or protein expressionStudy type (in vitro, animals, humans): in vitroImpact on pathway (including dose-response): 5,7-DMF: BaP-DNA binding was markedly inhibited and the BaP-induced part of the CYP1B1 mRNA expression (P

  6. Environmental polychlorinated biphenyl exposure and cytochromes P450 in raccoons (Procyon lotor).

    Science.gov (United States)

    Smith, Philip N; Bandiera, Stelvio M; Skipper, Sherry L; Johnson, Kevin A; McMurry, Scott T

    2003-02-01

    An investigation involving raccoons as a sentinel species at the Paducah Gaseous Diffusion Plant (PGDP) and Ballard Wildlife Management Area in western Kentucky (USA) delineated the extent of exposure to polychlorinated biphenyls (PCBs). Three separate measures of hepatic cytochrome P450 (CYP) induction were used to evaluate raccoon physiological responses to PCB exposure. Hepatic CYP induction was estimated via determination of total CYP, dealkylase activities, and immunoreactive proteins. There were no differences in raccoon biomarker responses between study sites. Significant relationships between and among PCB residues and biomarkers indicated that hepatic CYP induction had occurred in response to PCB exposure. Pentoxyresorufin O-deethylase (PROD) activity, CYP1A1, and CYP1A2 were biomarkers most closely associated with PCB exposure. The rank order of responses was CYP1A1 > CYP1A2 > PROD > ethoxyresorufin O-deethylase (EROD) as related to raccoon liver PCB concentrations, whereas the order was CYP1A1 > PROD > EROD > CYP1A2 when regressed with total PCB concentrations in abdominal fat.

  7. Cytochrome P450 1B1, a novel chemopreventive target for benzo[a]pyrene-initiated human esophageal cancer.

    Science.gov (United States)

    Wen, Xia; Walle, Thomas

    2007-02-08

    Esophageal cancer is common worldwide, with poor prognosis. Smoking, including exposure to polyaromatic hydrocarbons like benzo[a]pyrene (BaP), is a major risk factor. In human esophageal HET-1A cells, we found that time-dependent BaP-DNA binding was associated with upregulation of CYP1B1, but not CYP1A1, mRNA and protein. The dietary flavonoid 5,7-dimethoxyflavone significantly inhibited BaP-DNA binding and down-regulated BaP-induced CYP1B1 mRNA and protein. 3',4'-Dimethoxyflavone was an even more potent inhibitor of CYP1B1 expression, while resveratrol had no effect. Thus, dietary methoxylated flavones inhibited BaP-induced CYP1B1 transcription in a cell-specific manner and hold promise as chemopreventive agents in esophageal carcinogenesis.

  8. Evidence for the activation of organophosphate pesticides by cytochromes P450 3A4 and 2D6 in human liver microsomes.

    Science.gov (United States)

    Sams, C; Mason, H J; Rawbone, R

    2000-08-16

    The role of specific cytochrome P450 isoforms in catalysing the oxidative biotransformation of the organophosphorothioate pesticides parathion, chlorpyrifos and diazinon into structures that inhibit cholinesterase has been investigated in human liver microsomes using chemical inhibitors. Pesticides were incubated with human liver microsomes and production of the anticholinergic oxon metabolite was investigated by the inhibition of human serum cholinesterase. Quinidine and ketoconazole at 10 micromol/l inhibited oxidative biotransformation. Compared to control incubations (no inhibitor) where cholinesterase activity was inhibited to between 1 and 4% of control levels, incorporation of the CYP2D6 inhibitor quinidine into the microsomal incubation resulted in cholinesterase activity of 50% for parathion, 38% for diazinon and 30% for chlorpyrifos. Addition of the CYP3A4 inhibitor ketoconazole to microsomal incubations resulted in 66% cholinesterase activity with diazinon, 20% with parathion and 5% with chlorpyrifos. The unexpected finding that CYP2D6, as well as CYP3A4, catalysed oxidative biotransformation was confirmed for chlorpyrifos and parathion using microsomes prepared from a human lymphoblastoid cell line expressing CYP2D6. While parathion has been investigated only as a model compound, chlorpyrifos and diazinon are both very important, widely used pesticides and CYP2D6 appears to be an important enzyme in their bioactivation pathway. CYP2D6 is polymorphic and hence may influence individual susceptibility to exposure to chlorpyrifos and diazinon as well as other structurally similar pesticides.

  9. Structure-activity relationship and substrate-dependent phenomena in effects of ginsenosides on activities of drug-metabolizing P450 enzymes.

    Directory of Open Access Journals (Sweden)

    Miao Hao

    Full Text Available Ginseng, a traditional herbal medicine, may interact with several co-administered drugs in clinical settings, and ginsenosides, the major active components of ginseng, may be responsible for these ginseng-drug interactions (GDIs. Results from previous studies on ginsenosides' effects on human drug-metabolizing P450 enzymes are inconsistent and confusing. Herein, we first evaluated the inhibitory effects of fifteen ginsenosides and sapogenins on human CYP1A2, CYP2C9, CYP2C19, CYP2D6 and CYP3A4 enzymes by using commercially available fluorescent probes. The structure-activity relationship of their effects on the P450s was also explored and a pharmacophore model was established for CYP3A4. Moreover, substrate-dependent phenomena were found in ginsenosides' effects on CYP3A4 when another fluorescent probe was used, and were further confirmed in tests with conventional drug probes and human liver microsomes. These substrate-dependent effects of the ginsenosides may provide an explanation for the inconsistent results obtained in previous GDI reports.

  10. Cytotoxicity of acrylamide and its epoxide glycidamide in CHO cells expressing human cytochrome P450 2E1

    Institute of Scientific and Technical Information of China (English)

    Shoulin Wang; Xiaoyang He; Xinru Wang; Junyan Hong

    2006-01-01

    Objective: To investigate whether CYP2E1 is responsible for the acrylamide metabolic activation in Flp-In CHO cell system. Methods: CYP2E1 cDNA was subcloned from the human liver full-length cDNA library and subsequently transfected into the Flp-In CHO cells to generate the stable transfectant of CYP2E1. The CYP2E1 mRNA expression was determined by RT-PCR. Acrylamide and its epoxide glycidamide induced cytotoxicity and cell cycle arrest in G2/M were conducted using MTS assay and flow cytometry, respectively. Results: In the CHO cell stably expressing CYP2E1 (CHO-2E1), a ~1.5 kbsize of band was detected from the mRNA in the cells while no corresponding band in the CHO-vector cells, which indicated that CYP2E1 was successfully transfected in the CHO cells. Compared with the CHO-vector cells, acrylamide showed a concentrationdependent loss of viability in the CHO-2E1 cells but no significant change of G2/M arrest was found. As expected, glycidamide induced similar profile of cytotoxicity in both of the cells, and G2/M arrest presented a concentration-dependent increased in the CHO-2E1 cells. Conclusion: The result suggested that CYP2E1 might be responsible for the acrylamide metabolism, and its metabolite glycidamide was a direct cytotoxic and genotoxic agent. It should be further considered whether acrylamide-induced toxicity is through its epoxide glycidamide in the presence of CYP2E1.

  11. Effects of methoxychlor and 2,2-bis ( p -hydroxyphenyl)-1,1,1-trichloroethane on cytochrome P450 enzyme activities in human and rat livers.

    Science.gov (United States)

    Chen, Bingbing; Pan, Peipei; Wang, Li; Chen, Menchun; Dong, Yaoyao; Ge, Ren-Shan; Hu, Guo-Xin

    2015-01-01

    Cytochrome P450 (CYP) enzymes are involved in the metabolism of endogenous and exogenous compounds. Human and rat liver microsomes were used to investigate the inhibitory effects of methoxychlor (MXC) and its metabolite 2,2-bis(p-hydroxyphenyl)-1,1,1-trichloroethane (HPTE) on the activities of corresponding human and rat CYPs. Probe drugs were used to test the inhibitory effects of MXC and HPTE on human and rat CYPs. The results showed that MXC and HPTE inhibited both human CYP2C9 and rat liver CYP2C11 activity, with half-maximal inhibitory concentration (IC50) values of 15.47 ± 0.36 (MXC) and 8.87 ± 0.53 μmol/l (HPTE) for human CYP2C9, and of 22.45 ± 1.48 (MXC) and 24.63 ± 1.35 μmol/l (HPTE) for rat CYP2C11. MXC and HPTE had no effects on human CYP2C19 activity but inhibited rat CYP2C6 activity with IC50 values of 14.84 ± 0.04 (MXC) and 8.72 ± 0.25 μmol/l (HPTE). With regard to human CYP2D6 and rat CYP2D2 activity, only HPTE potently inhibited human CYP2D6 activity, with an IC50 value of 16.56 ± 0.69 μmol/l. Both chemicals had no effect on human CYP3A4 and rat CYP3A1 activity. In summary, MXC and HPTE are potent inhibitors of some human and rat CYPs.

  12. CROSS-SPECIES COMPARISON OF CONAZOLE FUNGICIDE METABOLITES USING RAT AND RAINBOW TROUT (ONCHORHYNCHUS MYKISS) HEPATIC MICROSOMES AND PURIFIED HUMAN CYTOCHROME P450 3A4

    Science.gov (United States)

    Conazoles represent a unique class of azole-containing fungicides that are widely used in both pharmaceutical and agriculture applications. The antifungal property of conazoles occurs via complexation with cytochrome P450 monooxygenases (CYP) responsible for mediating fungal cell...

  13. INTERINDIVIDUAL VARIANCE OF CYTOCHROME P450 FORMS IN HUMAN HEPATIC MICROSOMES: CORRELATION OF INDIVIDUAL FORMS WITH XENOBIOTIC METABOLISM AND IMPLICATIONS IN RISK ASSESSMENT

    Science.gov (United States)

    Differences in biotransformation activities may alter the bioavailability or efficacy of drugs, provide protection from certain xenobiotic and environmental agents, or increase toxicity of others. Cytochrome P450 (CYP450) enzymes are responsible for the majority of oxidation reac...

  14. Effect of human glutathione S-transferases on glutathione-dependent inactivation of cytochrome P450-dependent reactive intermediates of diclofenac.

    Science.gov (United States)

    Dragovic, Sanja; Boerma, Jan Simon; Vermeulen, Nico P E; Commandeur, Jan N M

    2013-11-18

    Idiosyncratic adverse drug reactions due to the anti-inflammatory drug diclofenac have been proposed to be caused by the generation of reactive acyl glucuronides and oxidative metabolites. For the oxidative metabolism of diclofenac by cytochromes P450 at least five different reactive intermediates have been proposed previously based on structural identification of their corresponding GSH-conjugates. In the present study, the ability of four human glutathione S-transferases (hGSTs) to catalyze the GSH-conjugation of the different reactive intermediates formed by P450s was investigated. Addition of pooled human liver cytosol and recombinant hGSTA1-1, hGSTM1-1, and hGSTP1-1 to incubations of diclofenac with human liver microsomes or purified CYP102A1M11 L437N as a model system significantly increased total GSH-conjugation. The strongest increase of total GSH-conjugation was observed by adding hGSTP1-1, whereas hGSTM1-1 and hGSTA1-1 showed lower activity. Addition of hGSTT1-1 only showed a minor effect. When considering the effects of hGSTs on GSH-conjugation of the different quinoneimines of diclofenac, it was found that hGSTP1-1 showed the highest activity in GSH-conjugation of the quinoneimine derived from 5-hydroxydiclofenac (5-OH-DF). hGSTM1-1 showed the highest activity in inactivation of the quinoneimine derived from 4'-hydroxydiclofenac (4'-OH-DF). Separate incubations with 5-OH-DF and 4'-OH-DF as substrates confirmed these results. hGSTs also catalyzed GSH-conjugation of the o-iminemethide formed by oxidative decarboxylation of diclofenac as well as the substitution of one of the chlorine atoms of DF by GSH. hGSTP1-1 showed the highest activity for the formation of these minor GSH-conjugates. These results suggest that hGSTs may play an important role in the inactivation of DF quinoneimines and its minor reactive intermediates especially in stress conditions when tissue levels of GSH are decreased.

  15. Comparative Cytochrome P450 In Vitro Inhibition by Atypical Antipsychotic Drugs

    OpenAIRE

    Guillermo Gervasini; Caballero, Maria J.; Carrillo, Juan A.; Julio Benitez

    2013-01-01

    The goal of this study was to assess in human liver microsomes the inhibitory capacity of commonly used antipsychotics on the most prominent CYP450 drug metabolizing enzymes (CYP1A2, CYP2C9, CYP2D6, and CYP3A). Chlorpromazine was the only antipsychotic that inhibited CYP1A2 activity (IC50 = 9.5  μ M), whilst levomepromazine, chlorpromazine, and thioridazine significantly decreased CYP2D6-mediated formation of 1′-hydroxybufuralol (IC50 range, 3.5–25.5  μ M). Olanzapine inhibited CYP3A-catalyze...

  16. Assessment of inhibitory effects on major human cytochrome P450 enzymes by spasmolytics used in the treatment of overactive bladder syndrome

    Science.gov (United States)

    Dahlinger, Dominik; Aslan, Sevinc; Pietsch, Markus; Frechen, Sebastian; Fuhr, Uwe

    2017-01-01

    Background: The objective of this study was to examine the inhibitory potential of darifenacin, fesoterodine, oxybutynin, propiverine, solifenacin, tolterodine and trospium chloride on the seven major human cytochrome P450 enzymes (CYP) by using a standardized and validated seven-in-one cytochrome P450 cocktail inhibition assay. Methods: An in vitro cocktail of seven highly selective probe substrates was incubated with human liver microsomes and varying concentrations of the seven test compounds. The major metabolites of the probe substrates were simultaneously analysed using a validated liquid chromatography tandem mass spectrometry (LC-MS/MS) method. Enzyme kinetics were estimated by determining IC50 and Ki values via nonlinear regression. Obtained Ki values were used for predictions of potential clinical impact of the inhibition using a static mechanistic prediction model. Results: In this study, 49 IC50 experiments were conducted. In six cases, IC50 values lower than the calculated threshold for drug–drug interactions (DDIs) in the gut wall were observed. In these cases, no increase in inhibition was determined after a 30 min preincubation. Considering a typical dosing regimen and applying the obtained Ki values of 0.72 µM (darifenacin, 15 mg daily) and 7.2 µM [propiverine, 30 mg daily, immediate release (IR)] for the inhibition of CYP2D6 yielded a predicted 1.9-fold and 1.4-fold increase in the area under the curve (AUC) of debrisoquine (CYP2D6 substrate), respectively. Due to the inhibition of the particular intestinal CYP3A4, the obtained Ki values of 14 µM of propiverine (30 mg daily, IR) resulted in a predicted doubling of the AUC for midazolam (CYP3A4 substrate). Conclusions: In vitro/in vivo extrapolation based on pharmacokinetic data and the conducted screening experiments yielded similar effects of darifenacin on CYP2D6 and propiverine on CYP3A4 as obtained in separately conducted in vivo DDI studies. As a novel finding, propiverine was identified

  17. Assessment of inhibitory effects on major human cytochrome P450 enzymes by spasmolytics used in the treatment of overactive bladder syndrome.

    Science.gov (United States)

    Dahlinger, Dominik; Aslan, Sevinc; Pietsch, Markus; Frechen, Sebastian; Fuhr, Uwe

    2017-07-01

    The objective of this study was to examine the inhibitory potential of darifenacin, fesoterodine, oxybutynin, propiverine, solifenacin, tolterodine and trospium chloride on the seven major human cytochrome P450 enzymes (CYP) by using a standardized and validated seven-in-one cytochrome P450 cocktail inhibition assay. An in vitro cocktail of seven highly selective probe substrates was incubated with human liver microsomes and varying concentrations of the seven test compounds. The major metabolites of the probe substrates were simultaneously analysed using a validated liquid chromatography tandem mass spectrometry (LC-MS/MS) method. Enzyme kinetics were estimated by determining IC50 and Ki values via nonlinear regression. Obtained Ki values were used for predictions of potential clinical impact of the inhibition using a static mechanistic prediction model. In this study, 49 IC50 experiments were conducted. In six cases, IC50 values lower than the calculated threshold for drug-drug interactions (DDIs) in the gut wall were observed. In these cases, no increase in inhibition was determined after a 30 min preincubation. Considering a typical dosing regimen and applying the obtained Ki values of 0.72 µM (darifenacin, 15 mg daily) and 7.2 µM [propiverine, 30 mg daily, immediate release (IR)] for the inhibition of CYP2D6 yielded a predicted 1.9-fold and 1.4-fold increase in the area under the curve (AUC) of debrisoquine (CYP2D6 substrate), respectively. Due to the inhibition of the particular intestinal CYP3A4, the obtained Ki values of 14 µM of propiverine (30 mg daily, IR) resulted in a predicted doubling of the AUC for midazolam (CYP3A4 substrate). In vitro/in vivo extrapolation based on pharmacokinetic data and the conducted screening experiments yielded similar effects of darifenacin on CYP2D6 and propiverine on CYP3A4 as obtained in separately conducted in vivo DDI studies. As a novel finding, propiverine was identified to potentially inhibit CYP2D6 at clinically

  18. Influences of 3-methylcholanthrene, phenobarbital and dexamethasone on xenobiotic metabolizing-related cytochrome P450 enzymes and steroidogenesis in human fetal adrenal cortical cells

    Institute of Scientific and Technical Information of China (English)

    Hui WANG; Min HUANG; Ren-xiu PENG; Jiang LE

    2006-01-01

    Aim: To explore the influence and possible mechanism of xenobiotics on adrenal steroidogenesis during fetal development. Methods: Primary human fetal adrenal cortical cells were prepared, cultured and treated with 3-methylcholanthrene, phenobarbital and dexamethasone. The activities of 7-ethoxyresorufin 0-dealkylase, benzphetamine, aminopyrine and erythromycin N-demethylases were measured by enzyme assays. At the same time, quantitative analysis of steroid hormones cortisol, aldosterone, testosterone and progesterone were carried out in cultural medium by radioimmunoassays. Results: The activities of benzphetamine and aminopyrine Ar-demethylase were increased in the cultural fetal adrenal cells treated with phenobarbital (0.25-1 mmol/L) for 24 h. Dexamethasone (25-100 μmol/L) also increased the activity of erythromycin W-demethylase. The activity of 7-ethoxyresorufin 0-dealkylase was undetected in the cells treated without and with 3-methylcholanthrene (0.5-2 μmol/L). Meanwhile, the contents of medium cortisol, aldosterone and progesterone were decreased after treatment with 3-methylcholanthrene. Cortisol, aldosterone and progesterone concentrations were also slightly decreased with phenobarbital. Dexamethasone enhanced the productions of cortisol and progesterone remarkably. The trend of testosterone concentration was uncertain after 3-methylcholanthrene, phenobarbital or dexamethasone treatment. Conclusion: 3-Methylcholanthrene, phenobarbital or dexamethasone could interfere with the synthesis of cortisol, aldosterone and progesterone in primary human fetal adrenal cortical cells, which likely act through xenobiotic metabolizing-related cytochrome P450 isoform activation.

  19. Traditional Preparations and Methanol Extracts of Medicinal Plants from Papua New Guinea Exhibit Similar Cytochrome P450 Inhibition

    Directory of Open Access Journals (Sweden)

    Erica C. Larson

    2016-01-01

    Full Text Available The hypothesis underlying this current work is that fresh juice expressed from Papua New Guinea (PNG medicinal plants (succus will inhibit human Cytochrome P450s (CYPs. The CYP inhibitory activity identified in fresh material was compared with inhibition in methanol extracts of dried material. Succus is the most common method of traditional medicine (TM preparation for consumption in PNG. There is increasing concern that TMs might antagonize or complicate drug therapy. We have previously shown that methanol extracts of commonly consumed PNG medicinal plants are able to induce and/or inhibit human CYPs in vitro. In this current work plant succus was prepared from fresh plant leaves. Inhibition of three major CYPs was determined using human liver microsomes and enzyme-selective model substrates. Of 15 species tested, succus from 6/15 was found to inhibit CYP1A2, 7/15 inhibited CYP3A4, and 4/15 inhibited CYP2D6. Chi-squared tests determined differences in inhibitory activity between succus and methanol preparations. Over 80% agreement was found. Thus, fresh juice from PNG medicinal plants does exhibit the potential to complicate drug therapy in at risk populations. Further, the general reproducibility of these findings suggests that methanol extraction of dried material is a reasonable surrogate preparation method for fresh plant samples.

  20. Development and validation of a fast and sensitive UPLC-MS/MS method for the quantification of six probe metabolites for the in vitro determination of cytochrome P450 activity

    NARCIS (Netherlands)

    De Bock, Lies; Boussery, Koen; Colin, Pieter; De Smet, Julie; T'Jollyn, Huybrecht; Van Bocxlaer, Jan

    2012-01-01

    A fast and sensitive UPLC-MS/MS method was developed and validated for the simultaneous quantification of six probe metabolites for the in vitro cytochrome P450 activity determination in hepatic microsomes from patients with hepatic impairment. The metabolites acetaminophen (CYP1A2), 4'-hydroxy-meph

  1. Cytochrome P450c17 (steroid 17. cap alpha. -hydroxylase/17,20 lyase): cloning of human adrenal and testis cDNAs indicates the same gene is expressed in both tissues

    Energy Technology Data Exchange (ETDEWEB)

    Chung, B.; Picado-Leonard, J.; Haniu, M.; Bienkowski, M.; Hall, P.F.; Shively, J.E.; Miller, W.L.

    1987-01-01

    P450c17 is the single enzyme mediating both 17..cap alpha..-hydroxylase (steroid 17..cap alpha..-monooxygenase, EC 1.14.99.9) and 17,20 lyase activities in the synthesis of steroid hormones. It has been suggested that different P450c17 isozymes mediate these activities in the adrenal gland and testis. The authors sequenced 423 of the 509 amino acids (83%) of the porcine adrenal enzyme; based on this partial sequence, a 128-fold degenerate 17-mer was synthesized and used to screen a porcine adrenal cDNA library. This yielded a 380-base cloned cDNA, which in turn was used to isolate several human adrenal cDNAs. The longest of these, lambda hac 17-2, is 1754 base pairs long and includes the full-length coding region, the complete 3'-untranslated region, and 41 bases of the 5'-untranslated region. This cDNA encodes a protein of 508 amino acids having a predicted molecular weight of 57,379.82. High-stringency screening of a human testicular cDNA library yielded a partial clone containing 1303 identical bases. RNA gel blots and nuclease S1-protection experiments confirm that the adrenal and testicular P450c17 mRNAs are indistinguishable. These data indicate that the testis possesses a P450c17 identical to that in the adrenal. The human amino acid sequence is 66.7% homologous to the corresponding regions of the porcine sequence, and the human cDNA and amino acid sequences are 80.1 and 70.3% homologous, respectively, to bovine adrenal P450c17 cDNA. Both comparisons indicate that a central region comprising amino acid residues 160-268 is hypervariable among these species of P450c17.

  2. A pharmacometric approach to investigate the impact of methylxanthine abstinence and caffeine consumption on CYP1A2 activity.

    Science.gov (United States)

    Perera, Vidya; Gross, Annette S; Forrest, Alan; Landersdorfer, Cornelia B; Xu, Hongmei; Ait-Oudhia, Sihem; McLachlan, Andrew J

    2013-11-01

    This study aimed to investigate the impact of methylxanthine abstinence (MA) periods on CYP1A2 activity in individuals with varying levels of caffeine consumption through development of a population pharmacokinetic model of caffeine and its major metabolite paraxanthine. This study developed and evaluated a mixed-effects pharmacokinetic model for caffeine and paraxanthine concentration-time data derived from a sequential single-dose cross-over study in healthy male volunteers (n = 30) who received oral 100 mg caffeine doses. Participants received caffeine with and without a MA period. Participants were classified as low (0-100 mg/d), medium (100-200 mg/d), or high (>200 mg/d) caffeine consumers (LCCs, MCCs, or HCCs, respectively). All caffeine and paraxanthine concentration-time data were simultaneously modeled. Caffeine pharmacokinetics was described by a two-compartment model with first-order absorption and two first-order elimination pathways. Paraxanthine was described by a one-compartment model with first-order absorption and elimination. Among LCCs (n = 16) and MCCs (n = 9), there was no difference in the mean (95% confidence interval) total apparent caffeine clearance (CL) between the MA period [LCCs: 6.88 (5.61-8.16 l/h); MCCs: 10.09 (7.57-12.60 l/h)] versus the no MA period [LCCs: 6.22 (4.97-7.46 l/h); MCCs: 9.68 (7.12-12.24 l/h)]. The mean CL among HCCs (n = 5) was considerably higher in the MA period [10.48 (5.62-15.33 l/h)] compared with the no MA period [6.30 (3.40-9.20 l/h)] (P caffeine elimination pathways, rather than CYP1A2.

  3. Endothelial expression of human cytochrome P450 epoxygenase CYP2C8 increases susceptibility to ischemia-reperfusion injury in isolated mouse heart

    Science.gov (United States)

    Edin, Matthew L.; Wang, ZhongJing; Bradbury, J. Alyce; Graves, Joan P.; Lih, Fred B.; DeGraff, Laura M.; Foley, Julie F.; Torphy, Robert; Ronnekleiv, Oline K.; Tomer, Kenneth B.; Lee, Craig R.; Zeldin, Darryl C.

    2011-01-01

    Cytochrome P450 (CYP) epoxygenases CYP2C8 and CYP2J2 generate epoxyeicosatrienoic acids (EETs) from arachidonic acid. Mice with expression of CYP2J2 in cardiomyocytes (αMHC-CYP2J2 Tr) or treated with synthetic EETs have increased functional recovery after ischemia/reperfusion (I/R); however, no studies have examined the role of cardiomyocyte- vs. endothelial-derived EETs or compared the effects of different CYP epoxygenase isoforms in the ischemic heart. We generated transgenic mice with increased endothelial EET biosynthesis (Tie2-CYP2C8 Tr and Tie2-CYP2J2 Tr) or EET hydrolysis (Tie2-sEH Tr). Compared to wild-type (WT), αMHC-CYP2J2 Tr hearts showed increased recovery of left ventricular developed pressure (LVDP) and decreased infarct size after I/R. In contrast, LVDP recovery and infarct size were unchanged in Tie2-CYP2J2 Tr and Tie2-sEH Tr hearts. Surprisingly, compared to WT, Tie2-CYP2C8 Tr hearts had significantly reduced LVDP recovery (from 21 to 14%) and increased infarct size after I/R (from 51 to 61%). Tie2-CYP2C8 Tr hearts also exhibited increased reactive oxygen species (ROS) generation, dihydroxyoctadecenoic acid (DiHOME) formation, and coronary resistance after I/R. ROS scavengers and CYP2C8 inhibition reversed the detrimental effects of CYP2C8 expression in Tie2-CYP2C8 Tr hearts. Treatment of WT hearts with 250 nM 9,10-DiHOME decreased LVDP recovery compared to vehicle (16 vs. 31%, respectively) and increased coronary resistance after I/R. These data demonstrate that increased ROS generation and enhanced DiHOME synthesis by endothelial CYP2C8 impair functional recovery and mask the beneficial effects of increased EET production following I/R.—Edin, M. L., Wang, Z. J., Bradbury, J. A., Graves, J. P., Lih, F. B., DeGraff, L. M., Foley, J. F., Torphy, R., Ronnekleiv, O. K., Tomer, K. B., Lee, C. R., Zeldin, D. C. Endothelial expression of human cytochrome P450 epoxygenase CYP2C8 increases susceptibility to ischemia-reperfusion injury in isolated mouse

  4. El splicing alternativo del exón 5 de la citocromo p450 aromatasa podría ser un mecanismo de regulación de la producción de estrógenos en humanos Exon 5 alternative splicing of the cytochrome P450 aromatase could be a regulatory mechanism for estrogen production in humans

    Directory of Open Access Journals (Sweden)

    Carolina M. Pepe

    2007-08-01

    adult male with P450Aro deficiency results in an aberrant splicing due to disruption of a donor splice site. A truncated inactive protein would be expected if intron5 is retained. Surprisingly, the girl described with this mutation showed spontaneous breast development and pubertal estradiol (E2 levels suggesting residual P450Aro activity (AA. Formerly, we postulate the in frame E5 skipping as a consequence of this mutation generating a protein with some degree of activity. When P450Aro mRNA expression was analysed from patient's lymphocytes, an aberrant spliced mRNA lacking E5 (-E5mRNA was detected, suggesting an association between E5 skipping and the presence of the mutation. Splicing assays in Y1 cells confirmed this association. -Ex5 cDNA expression in Y1 cells resulted in an inactive protein that could not explain patient's phenotype. Exon 5 might be predicted as a poorly defined exon suggesting a susceptibility to splicing mutations and physiological alternative splicing (AS events. Therefore, -Ex5mRNA was assessed as a natural occurring alternative transcript in normal human steroidogenic tissues. As P450Aro -E5mRNA expression was detected in human term placenta, prepubertal testis and prepubertal adrenal, we might speculate that AS of P450Aro coding region would occur in humans and would be involved in the complex AA regulation. Furthermore, tissue specific regulation of AS might suggest low expression of +E5mRNA from the c655G>A allele explaining residual AA evidenced in the affected girl.

  5. Regulation of human pregnane X receptor and its target gene cytochrome P450 3A4 by Chinese herbal compounds and a molecular docking study.

    Science.gov (United States)

    Liu, Ya-He; Mo, Sui-Lin; Bi, Hui-Chang; Hu, Bing-Fang; Li, Chun Guang; Wang, Yi-Tao; Huang, Ling; Huang, Min; Duan, Wei; Liu, Jun-Ping; Wei, Ming Qian; Zhou, Shu-Feng

    2011-04-01

    The pregnane X receptor (PXR) plays a critical role in the regulation of human cytochrome P450 3A4 (CYP3A4) gene. In this study, we investigated the effect of an array of compounds isolated from Chinese herbal medicines on the activity of PXR using a luciferase reporter gene assay in transiently transfected HepG2 and Huh7 cells and on the expression of PXR and CYP3A4 in LS174T cells. Furthermore, molecular docking was performed to investigate the binding modes of herbal compounds with PXR. Praeruptorin A and C, salvianolic acid B, sodium danshensu, protocatechuic aldehyde, cryptotanshinone, emodin, morin, and tanshinone IIA significantly transactivated the CYP3A4 reporter gene construct in either HepG2 or Huh7 cells. The PXR mRNA expression in LS174T cells was significantly induced by physcion, protocatechuic aldehyde, salvianolic acid B, and sodium danshensu. However, epifriedelanol, morin, praeruptorin D, mulberroside A, tanshinone I, and tanshinone IIA significantly down-regulated the expression of PXR mRNA in LS174T cells. All the herbal compounds tested can be readily docked into the ligand-binding cavity of PXR mainly through hydrogen bond and aromatic interactions with Ser247, Gln285, His407, and Arg401. These findings suggest that herbal medicines can significantly regulate PXR and CYP3A4 and this has important implication in herb-drug interactions.

  6. Inhibition on human liver cytochrome P450 3A4 by constituents of fennel (Foeniculum vulgare): identification and characterization of a mechanism-based inactivator.

    Science.gov (United States)

    Subehan; Zaidi, Syed F H; Kadota, Shigetoshi; Tezuka, Yasuhiro

    2007-12-12

    Fennel, a seed of Foeniculum vulgare, is used as a culinary spice and traditional medicine. The methanolic extract of fennel showed a characteristic of mechanism-based inactivation on erythromycin N-demethylation mediated by human liver microsomal cytochrome P450 3A4 (CYP3A4). The present study was conducted to identify the fennel constituent having the inhibition. Thirteen compounds have been isolated from a methanol extract of fennel and tested for their inhibition on CYP3A4. Among them, 5-methoxypsoralen (5-MOP) showed the strongest inhibition with an IC50 value of 18.3 microM and a mixed type of inhibition. In addition, with the preincubation time of 20 min only 5-MOP showed preincubation time dependency; the IC50 value decreased from 18.3 microM with a preincubation time of 0 min to 4.6 microM with a preincubation time of 20 min. Further investigation on 5-MOP showed the characteristics of time-dependent inhibition, requirement of NADPH, lack of protecting effect of nucleophiles, and recovery of CYP3A4 activity by the competitive inhibitor. This result suggests that the inhibitory activity of CYP3A4 by 5-MOP was a mechanism-based inactivation. The kinetic parameter for mechanism-based inactivation was characterized by a KI value of 15.0 microM and a kinact value of 0.098 min(-1).

  7. A high-throughput inhibition screening of major human cytochrome P450 enzymes using an in vitro cocktail and liquid chromatography-tandem mass spectrometry.

    Science.gov (United States)

    Qin, Chong-Zhen; Ren, Xian; Tan, Zhi-Rong; Chen, Yao; Yin, Ji-Ye; Yu, Jing; Qu, Jian; Zhou, Hong-Hao; Liu, Zhao-Qian

    2014-02-01

    A sensitive and high-throughput inhibition screening liquid chromatography-mass spectrometry (LC-MS/MS) method was developed and validated for the simultaneous quantification of five probe metabolites (7-hydroxycoumarin, CYP2A6; 4-hydroxytolbutamide, CYP2C9; 4'-hydroxymephenytoin, CYP2C19; α-hydroxymetoprolol, CYP2D6; and 1-hydroxymidazolam, CYP3A4) for in vitro cytochrome P450 activity determination in human liver microsome and recombinant. All the metabolites and the internal standard, tramadol, were separated on a Waters 2695 series liquid chromatograph with a Phenomenex Luna C18 column (150 × 2.0 mm, 5 µm). Quality control samples and a positive control CYP inhibitor were included in the method. The IC50 values determined for typical CYP inhibitors were reproducible and in agreement with the literature. The method was selective and showed good accuracy (99.13-103.37%), and inter-day (RSD high-quality and -throughput cocktail provides suitable information in drug discovery and screening for new drug entities.

  8. Induction of CYP1A1, CYP1A2, CYP1B1, increased oxidative stress and inflammation in the lung and liver tissues of rats exposed to incense smoke.

    Science.gov (United States)

    Hussain, Tajamul; Al-Attas, Omar S; Al-Daghri, Nasser M; Mohammed, Arif A; De Rosas, Edgard; Ibrahim, Shebl; Vinodson, Benjamin; Ansari, Mohammed G; El-Din, Khaled I Alam

    2014-06-01

    Incense smoke is increasingly being recognized as a potential environmental contaminant and is linked to malignant and non-malignant respiratory diseases. The detoxification of environmental contaminants including polycyclic aromatic hydrocarbons (PAHs) involves the induction of cytochrome P-450 family enzymes (CYPs) by PAHs. However, the detoxification of PAHs also results in the generation of reactive and unstable intermediary metabolites which are implicated in the oxidative stress, DNA damage, and inflammation. It is unclear whether CYPs are similarly induced by incense smoke, which incidentally contains substantial amounts of PAHs. Here, we examined the impact of long-term incense smoke exposure on the induction of CYPs in male Wister Albino rats. Incense smoke exposure significantly induced the expression of CYP1A1, CYP1A2, and CYP1B1 mRNAs in both lung and liver tissues. The extent of CYP1A1 and CYP1B1 induction was significantly higher in the liver compared to that in the lung, while that of CYP1A2 was greater in the lung than in liver. Incense smoke exposure also increased malondialdehyde and reduced glutathione levels in lung and liver tissues, and the catalase activity in the liver tissues to significant levels. Furthermore incense smoke exposure led to a marked increase in TNF-α and IL-4 levels. The data demonstrate for the first time the capacity of incense smoke to induce CYP1 family enzymes in the target and non-target tissues. Induction of CYPs increased oxidative stress and inflammation appear to be intimately linked to promote the carcinogenesis and health complications in people chronically exposed to incense smoke.

  9. In vitro drug-drug interactions of budesonide: inhibition and induction of transporters and cytochrome P450 enzymes.

    Science.gov (United States)

    Chen, Nancy; Cui, Donghui; Wang, Qing; Wen, Zhiming; Finkelman, Richard D; Welty, Devin

    2017-07-21

    1. Budesonide is a glucocorticoid used in the treatment of several respiratory and gastrointestinal inflammatory diseases. Glucocorticoids have been demonstrated to induce cytochrome P450 (CYP) 3A and the efflux transporter P-glycoprotein (P-gp). This study aimed to evaluate the potential of budesonide to act as a perpetrator or a victim of transporter- or CYP-mediated drug-drug interactions (DDIs). 2. In vitro studies were conducted for P-gp, breast cancer resistance protein and organic anion and cation transporters (OATP1B1, OATP1B3, OAT1, OAT3, OCT2) in transporter-transfected cells. Changes in mRNA expression in human hepatocytes and enzyme activity in human liver microsomes by budesonide were determined for CYP1A2, CYP2B6, CYP2C8, CYP2C9, CYP2C19, CYP2D6 and CYP3A. 3. The data indicated that budesonide is a substrate of P-gp but is not a substrate or an inhibitor of the other transporters investigated. Budesonide is neither an inducer nor an inhibitor of major CYP enzymes. The effect of P-gp on budesonide disposition is anticipated to be low owing to CYP3A-mediated clearance. 4. Collectively, our data indicate there is a low risk of budesonide perpetrating clinical DDIs mediated by the transporters or CYPs studied.

  10. Cytochrome P450-mediated oxidative metabolism of abused synthetic cannabinoids found in K2/Spice: identification of novel cannabinoid receptor ligands.

    Science.gov (United States)

    Chimalakonda, Krishna C; Seely, Kathryn A; Bratton, Stacie M; Brents, Lisa K; Moran, Cindy L; Endres, Gregory W; James, Laura P; Hollenberg, Paul F; Prather, Paul L; Radominska-Pandya, Anna; Moran, Jeffery H

    2012-11-01

    Abuse of synthetic cannabinoids (SCs), such as [1-naphthalenyl-(1-pentyl-1H-indol-3-yl]-methanone (JWH-018) and [1-(5-fluoropentyl)-1H-indol-3-yl]-1-naphthalenyl-methanone (AM2201), is increasing at an alarming rate. Although very little is known about the metabolism and toxicology of these popular designer drugs, mass spectrometric analysis of human urine specimens after JWH-018 and AM2201 exposure identified monohydroxylated and carboxylated derivatives as major metabolites. The present study extends these initial findings by testing the hypothesis that JWH-018 and its fluorinated counterpart AM2201 are subject to cytochrome P450 (P450)-mediated oxidation, forming potent hydroxylated metabolites that retain significant affinity and activity at the cannabinoid 1 (CB(1)) receptor. Kinetic analysis using human liver microsomes and recombinant human protein identified CYP2C9 and CYP1A2 as major P450s involved in the oxidation of the JWH-018 and AM2201. In vitro metabolite formation mirrored human urinary metabolic profiles, and each of the primary enzymes exhibited high affinity (K(m) = 0.81-7.3 μM) and low to high reaction velocities (V(max) = 0.0053-2.7 nmol of product · min(-1) · nmol protein(-1)). The contribution of CYP2C19, 2D6, 2E1, and 3A4 in the hepatic metabolic clearance of these synthetic cannabinoids was minimal (f(m) = receptor, which was attenuated by the CB(1) receptor antagonist (6aR,10aR)-3-(1-methanesulfonylamino-4-hexyn-6-yl)-6a,7,10,10a-tetrahydro-6,6,9-trimethyl-6H-dibenzo[b,d]pyran (O-2050). Results from the present study provide critical, missing data related to potential toxicological properties of "K2" parent compounds and their human metabolites, including mechanism(s) of action at cannabinoid receptors.

  11. Membrane-bound human orphan cytochrome P450 2U1: Sequence singularities, construction of a full 3D model, and substrate docking.

    Science.gov (United States)

    Ducassou, Lionel; Dhers, Laura; Jonasson, Gabriella; Pietrancosta, Nicolas; Boucher, Jean-Luc; Mansuy, Daniel; André, François

    2017-09-01

    Human cytochrome P450 2U1 (CYP2U1) is an orphan CYP that exhibits several distinctive characteristics among the 57 human CYPs with a highly conserved sequence in almost all living organisms. We compared its protein sequence with those of the 57 human CYPs and constructed a 3D structure of a full-length CYP2U1 model bound to a POPC membrane. We also performed docking experiments of arachidonic acid (AA) and N-arachidonoylserotonin (AS) in this model. The protein sequence of CYP2U1 displayed two unique characteristics when compared to those of the human CYPs, the presence of a longer N-terminal region upstream of the putative trans-membrane helix (TMH) containing 8 proline residues, and of an insert of about 20 amino acids containing 5 arginine residues between helices A' and A. Its N-terminal part upstream of TMH involved an additional short terminal helix, in a manner similar to what was reported in the crystal structure of Saccharomyces cerevisiae CYP51. Our model also showed a specific interaction between the charged residues of insert AA' and phosphate groups of lipid polar heads, suggesting a possible role of this insert in substrate recruitment. Docking of AA and AS in this model showed these substrates in channel 2ac, with the terminal alkyl chain of AA or the indole ring of AS close to the heme, in agreement with the reported CYP2U1-catalyzed AA and AS hydroxylation regioselectivities. This model should be useful to find new endogenous or exogenous CYP2U1 substrates and to interpret the regioselectivity of their hydroxylation. Copyright © 2017 Elsevier B.V. and Société Française de Biochimie et Biologie Moléculaire (SFBBM). All rights reserved.

  12. Gomisin A is a Novel Isoform-Specific Probe for the Selective Sensing of Human Cytochrome P450 3A4 in Liver Microsomes and Living Cells.

    Science.gov (United States)

    Wu, Jing-Jing; Ge, Guang-Bo; He, Yu-Qi; Wang, Ping; Dai, Zi-Ru; Ning, Jing; Hu, Liang-Hai; Yang, Ling

    2016-01-01

    Nearly half of prescription medicines are metabolized by human cytochrome P450 (CYP) 3A. CYP3A4 and 3A5 are two major isoforms of human CYP3A and share most of the substrate spectrum. A very limited previous study distinguished the activity of CYP3A4 and CYP3A5, identifying the challenge in predicting CYP3A-mediated drug clearance and drug-drug interaction. In the present study, we introduced gomisin A (GA) with a dibenzocyclooctadiene skeleton as a novel selective probe of CYP3A4. The major metabolite of GA was fully characterized as 8-hydroxylated GA by LC-MS and NMR. CYP3A4 was assigned as the predominant isozyme involved in GA 8-hydroxylation by reaction phenotyping assays, chemical inhibition assays, and correlation studies. GA 8-hydroxylation in both recombinant human CYP3A4 and human liver microsomes followed classic Michaelis-Menten kinetics. The intrinsic clearance values indicated that CYP3A4 contributed 12.8-fold more than CYP3A5 to GA 8-hydroxylation. Molecular docking studies indicated different hydrogen bonds and π-π interactions between CYP3A4 and CYP3A5, which might result in the different catalytic activity for GA 8-hydroxylation. Furthermore, GA exhibited a stronger inhibitory activity towards CYP3A4 than CYP3A5, which further suggested a preferred selectivity of CYP3A4 for the transformation of GA. More importantly, GA has been successfully applied to selectively monitor the modulation of CYP3A4 activities by the inducer rifampin in hepG2 cells, which is consistent with the level change of CYP3A4 mRNA expression. In summary, our results suggested that GA could be used as a novel probe for the selective sensing of CYP3A4 in tissue and cell preparations.

  13. Establishment of a transgenic cell line stably expressing human cytochrome P450 2C18 and identification of a CYP2C18 clone with exon 5 missing

    Institute of Scientific and Technical Information of China (English)

    Jian Zhu-Ge; Ying-Nian Yu; Yu-Li Qian; Xin Li

    2002-01-01

    AIM: The human cytochrome P-450 2C18(CYP2C18) hasbeen characterized. However, the protein has not beenpurified from liver and very little is known regarding thespecific substrate of CYP2C18. In order to study its enzymaticactivity for drug metabolism, the CYP2C18cDNA was clonedand a stable CHL cell line expressing recombinant CYP 2C18was established.METHODS: The human CYP2C18cDNA was amplified withreverse transcription-polymerase chain reaction (RT-PCR)from total RNAs extracted from human liver and cloned intopGEM-T vector. The cDNA segment was identified by DNAsequencing and subcloned into a mammalian expressionvector pREP9. A transgenic cell line was established bytransfecting the recombinant plasmid of pREPg-CYP2C18toChinese hamster lung (CHL) cell. The enzyme activity ofCYP2C18 catalyzing oxidation of tolbutamide tohydroxytolbutamide in postmitochondrial supernant(Sg)fraction of the cell was determined by high performanceliquid chromatography(HPLC).RESULTS: The amino acid sequence predicted from thecloned cDNA segment was identical to that of reported byRomkes et al(GenBank accession number: M61856,J05326).The S9 fraction of the established cell line metabolizestolbutamide to hydroxytolbutamide. Tolbutamide hydroxylaseactivity was found to be 0.509±0.052 μmol.min-1.g-1 S9protein or 8.82±0.90 mol.min-1.mol-1 CYP, but wasundetectable in parental CHL cell. In addition, we haveidentified a CYP2C18cDNA clone with exon 5 missing.CONCLUSION: The cDNA of human CYP2C18 wassuccessfully cloned and a cell line, CHL-CYP2C18, efficientlyexpressing the protein of CYP2C18, was established. Aspliced variant of CYP2C18 with exon 5 missing was identifiedin the cloning process.

  14. Characterization of the structural determinants required for potent mechanism-based inhibition of human cytochrome P450 1A1 by cannabidiol.

    Science.gov (United States)

    Yamaori, Satoshi; Okushima, Yoshimi; Yamamoto, Ikuo; Watanabe, Kazuhito

    2014-05-25

    We previously demonstrated that cannabidiol (CBD) was a potent mechanism-based inhibitor of human cytochrome P450 1A1 (CYP1A1). However, the moiety of CBD that contributes to the potent mechanism-based inhibition of human CYP1A1 remains unknown. Thus, the effects of compounds structurally related to CBD on CYP1A1 activity were examined with recombinant human CYP1A1 in order to characterize the structural requirements for potent inactivation by CBD. When preincubated in the presence of NADPH for 20min, olivetol, which corresponds to the pentylresorcinol moiety of CBD, enhanced the inhibition of the 7-ethoxyresorufin O-deethylase activity of CYP1A1. In contrast, d-limonene, which corresponds to the terpene moiety of CBD, failed to inhibit CYP1A1 activity in a metabolism-dependent manner. Pentylbenzene, which lacks two free phenolic hydroxyl groups, also did not enhance CYP1A1 inhibition. On the other hand, preincubation of the CBD-2'-monomethyl ether (CBDM) and CBD-2',6'-dimethyl ether (CBDD) enhanced the inhibition of CYP1A1 activity. Inhibition by cannabidivarin (CBDV), which possessed a propyl side chain, was strongly potentiated by its preincubation. Orcinol, which has a methyl group, augmented CYP1A1 inhibition, whereas its derivative without an alkyl side chain, resorcinol, did not exhibit any metabolism-dependent inhibition. The preincubation of CBD-hydroxyquinone did not markedly enhance CYP1A1 inhibition. We further confirmed that olivetol, CBDM, CBDD, CBDV, and orcinol, as well as CBD (kinact=0.215min(-1)), inactivated CYP1A1 activity; their kinact values were 0.154, 0.0638, 0.0643, 0.226, and 0.0353min(-1), respectively. These results suggest that the methylresorcinol structure in CBD may have structurally important roles in the inactivation of CYP1A1.

  15. Differential expression of human cytochrome P450 enzymes from the CYP3A subfamily in the brains of alcoholic subjects and drug-free controls.

    Science.gov (United States)

    Booth Depaz, Iris M; Toselli, Francesca; Wilce, Peter A; Gillam, Elizabeth M J

    2013-06-01

    Cytochrome P450 enzymes are responsible for the metabolism of most commonly used drugs. Among these enzymes, CYP3A forms mediate the clearance of around 40-50% of drugs and may also play roles in the biotransformation of endogenous compounds. CYP3A forms are expressed both in the liver and extrahepatically. However, little is known about the expression of CYP3A proteins in specific regions of the human brain. In this study, form-selective antibodies raised to CYP3A4 and CYP3A5 were used to characterize the expression of these forms in the human brain. Both CYP3A4 and CYP3A5 immunoreactivity were found to varying extents in the microsomal fractions of cortex, hippocampus, basal ganglia, amygdala, and cerebellum. However, only CYP3A4 expression was observed in the mitochondrial fractions of these brain regions. N-terminal sequencing confirmed the principal antigen detected by the anti-CYP3A4 antibody in cortical microsomes to be CYP3A4. Immunohistochemical analysis revealed that CYP3A4 and CYP3A5 expression was primarily localized in the soma and axonal hillock of neurons and varied according to cell type and cell layer within brain regions. Finally, analysis of the frontal cortex of chronic alcohol abusers revealed elevated expression of CYP3A4 in microsomal but not mitochondrial fractions; CYP3A5 expression was unchanged. The site-specific expression of CYP3A4 and CYP3A5 in the human brain may have implications for the role of these enzymes in both normal brain physiology and the response to drugs.

  16. 复方丹参滴丸对大鼠肝细胞色素P450酶的影响%Effect of compound Danshen Dripping Pills on rat hepatic cytochrome P450

    Institute of Scientific and Technical Information of China (English)

    胡东华; 王宇光; 陈志武; 马增春; 梁乾德; 肖成荣; 谭洪玲; 汤响林; 李桦

    2013-01-01

    目的 观察复方丹参滴丸及其单味药对大鼠肝细胞色素P450酶(GYP)主要亚型的影响.方法 SD大鼠分别ig给予复方丹参滴丸0.3258 g·kg-1,丹参0.27 g·kg-1,三七0.0528 g· kg-1和冰片0.003 g·kg-1,每天1次,连续28 d,取大鼠肝微粒体,与CYP1 A2,CYP2B6,CYP2C12,CYP2C13,CYP2D2和CYP3A1特异性底物探针共孵育,用高效液相色谱-质谱联用仪(HPLC-MS/MS)测定底物的代谢产物,分析CYP1 A2,CYP2B6,CYP2C12,CYP2C13,CYP2D2和CYP3A1酶活性,同时用PCR方法检测cyp1 a2,cyp2b1/2,cyp2c11,cyp2e1和cyp3a1 mRNA表达的变化.结果 与正常对照组相比,苯巴比妥(阳性对照)对CYP2D2和CYP3A1活性有明显抑制作用,对CYP1 A2,CYP2B6,CYP2 C12和CYP2C13有明显诱导作用(P<0.05,P<0.01);复方丹参滴丸对CYP1 A2和CYP2B6活性有明显抑制作用,对CYP2D2有诱导作用(P<0.05);丹参对CYP1 A2和CYP2B6活性有明显抑制作用(P<0.05);三七对CYP1A2,CYP2B6,CYP2C13和CYP2D2活性有明显抑制作用(P<0.05);冰片明显抑制CYP1A2,CYP2B6,CYP2C12,CYP2C13和CYP2D2活性(P<0.01),且抑制强度高于复方丹参滴丸.与正常对照组相比,苯巴比妥对cyp1a2和cyp2b1/2 mRNA水平有明显诱导作用(P<0.05);复方丹参滴丸、丹参和三七对cyp1a2,cyp2b1/2,cyp2c11,cyp2e1和cyp3a1 mRNA水平无明显影响;冰片对cyp1a2,cyp2b1 /2和cyp2c1 1 mRNA水平有明显抑制作用(P<0.05,P<0.01).结论 复方丹参滴丸中各单味药对CYP酶的影响强于全方对CYP酶的影响,其中以冰片对药物代谢酶的影响最为显著.

  17. Hybrid cytochromes P-450 identify a substrate binding domain in P-450IIC5 and P-450IIC4.

    OpenAIRE

    Kronbach, T; Larabee, T M; Johnson, E F

    1989-01-01

    The cytochrome P-450 superfamily of enzymes catalyzes the oxidative metabolism of innumerable lipophilic compounds (e.g., drugs, carcinogens, steroids). Although the three-dimensional structure of a soluble bacterial P-450 (P-450cam) has been solved, little is known about the structures of the membrane-bound mammalian P-450s. Thus, the structural features of these enzymes that determine their multisubstrate specificity are unknown. In this report, we identify a segment of the primary structur...

  18. The stress response of human proximal tubule cells to cadmium involves up-regulation of haemoxygenase 1 and metallothionein but not cytochrome P450 enzymes.

    Science.gov (United States)

    Boonprasert, Kanyarat; Satarug, Soisungwan; Morais, Christudas; Gobe, Glenda C; Johnson, David W; Na-Bangchang, Kesara; Vesey, David A

    2016-05-13

    Enzymes of the cytochrome P450 (CYP) super-family are implicated in cadmium (Cd) -induced nephrotoxicity, however, direct evidence is lacking. This study investigated the endogenous expression of various CYP proteins together with the stress-response proteins, heme oxygenase-1 (HO-1) and metallothionein (MT) in human kidney sections and in cadmium-exposed primary cultures of human proximal tubular epithelial cells (PTC). By immunohistochemistry, the CYP members 2B6, 4A11 and 4F2 were prominently expressed in the cortical proximal tubular cells and to a lesser extent in distal tubular cells. Low levels of CYPs 2E1 and 3A4 were also detected. In PTC, in the absence of Cd, CYP2E1, CYP3A4, CYP4F2 and MT were expressed, but HO-1, CYP2B6 and CYP4A11 were not detected. A range of cadmium concentrations (0-100μM) were utilized to induce stress conditions. MT protein was further induced by as little as 0.5μM cadmium, reaching a 6-fold induction at 20μM, whereas for HO-1, a 5μM cadmium concentration was required for initial induction and at 20μM cadmium reached a 15-fold induction. The expression of CYP2E1, CYP3A4, and CYP4F2 were not altered by any cadmium concentrations tested at 48h. Cadmium caused a reduction in cell viability at concentrations above 10μM. In conclusion although cultured PTC, do express CYP proteins, (CYP2E1, CYP3A4, and CYP4F2), Cd-induced cell stress as indicted by induction of HO-1 and MT does not alter expression of these CYP proteins at 48h. Copyright © 2016 Elsevier Ireland Ltd. All rights reserved.

  19. Piperine activates human pregnane X receptor to induce the expression of cytochrome P450 3A4 and multidrug resistance protein 1

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Yue-Ming; Lin, Wenwei; Chai, Sergio C.; Wu, Jing; Ong, Su Sien [Department of Chemical Biology and Therapeutics, St. Jude Children' s Research Hospital, 262 Danny Thomas Place, Memphis, TN 38105 (United States); Schuetz, Erin G. [Department of Pharmaceutical Sciences, St. Jude Children' s Research Hospital, 262 Danny Thomas Place, Memphis, TN 38105 (United States); Chen, Taosheng, E-mail: taosheng.chen@stjude.org [Department of Chemical Biology and Therapeutics, St. Jude Children' s Research Hospital, 262 Danny Thomas Place, Memphis, TN 38105 (United States)

    2013-10-01

    Activation of the pregnane X receptor (PXR) and subsequently its target genes, including those encoding drug transporters and metabolizing enzymes, while playing substantial roles in xenobiotic detoxification, might cause undesired drug-drug interactions. Recently, an increased awareness has been given to dietary components for potential induction of diet–drug interactions through activation of PXR. Here, we studied, whether piperine (PIP), a major component extracted from the widely-used daily spice black pepper, could induce PXR-mediated expression of cytochrome P450 3A4 (CYP3A4) and multidrug resistance protein 1 (MDR1). Our results showed that PIP activated human PXR (hPXR)-mediated CYP3A4 and MDR1 expression in human hepatocytes, intestine cells, and a mouse model; PIP activated hPXR by recruiting its coactivator SRC-1 in both cellular and cell-free systems; PIP bound to the hPXR ligand binding domain in a competitive ligand binding assay in vitro. The dichotomous effects of PIP on induction of CYP3A4 and MDR1 expression observed here and inhibition of their activity reported elsewhere challenges the potential use of PIP as a bioavailability enhancer and suggests that caution should be taken in PIP consumption during drug treatment in patients, particularly those who favor daily pepper spice or rely on certain pepper remedies. - Highlights: • Piperine induces PXR-mediated CYP3A4 and MDR1 expression. • Piperine activates PXR by binding to PXR and recruiting coactivator SRC-1. • Piperine induces PXR activation in vivo. • Caution should be taken in piperine consumption during drug treatment.

  20. Selective and sensitive quantification of the cytochrome P450 3A4 protein in human liver homogenates through multiple reaction monitoring mass spectrometry.

    Science.gov (United States)

    Cieślak, Anna; Kelly, Isabelle; Trottier, Jocelyn; Verreault, Mélanie; Wunsch, Ewa; Milkiewicz, Piotr; Poirier, Guy; Droit, Arnaud; Barbier, Olivier

    2016-11-01

    This study aimed at establishing a sensitive multiple reaction monitoring-mass spectrometry (MRM-MS) method for the quantification of the drug metabolizing cytochrome P450 (CYP)3A4 enzyme in human liver homogenates. Liver samples were subjected to trypsin digestion. MRM-MS analyses were performed using three transitions optimized on one purified synthetic peptide unique to CYP3A4 and the standardizing protein, calnexin. Coefficient of variations for the precision and reproducibility of the MRM-MS measurement were also determined. The method was applied to liver samples from ten non-cholestatic donors and 34 cholestatic patients with primary biliary cholangitis (n = 12; PBC), primary sclerosing cholangitis (n = 10; PSC) or alcoholic liver disease (n = 12; ALD). The established method presented high sensitivity with limit of detection lower than 5 fmol, and was successfully applied for the absolute and relative quantification of CYP3A4 in both whole liver homogenate and microsomal fractions. When all groups were analyzed together, a significant correlation was observed for the MRM-based CYP3A4 protein quantification in homogenates and microsomes (r = 0.49, p < 0.001). No statistically significant difference was detected between CYP3A4 levels in PSC, PBC, ALD and control samples. Finally, the MRM-MS quantification of CYP3A4 in homogenates also correlated (r = 0.44; p < 0.05) with the level of enzyme activity in the same samples, as determined by measuring the chenodeoxycholic to hyocholic acid conversion. The established method provides a sensitive tool to evaluate the CYP3A4 protein in human liver homogenates from patients with normal or chronic/severe hepatic injury.

  1. Effects of dextran sulfate sodium induced experimental colitis on cytochrome P450 activities in rat liver, kidney and intestine.

    Science.gov (United States)

    Hu, Nan; Huang, Yanjuan; Gao, Xuejiao; Li, Sai; Yan, Zhixiang; Wei, Bin; Yan, Ru

    2017-06-01

    Dextran sulfate sodium (DSS) induced experimental colitis presents a histologic resemblance to human ulcerative colitis (UC). Altered cytochrome P450s (CYPs) have been reported in this model and patients with UC. In this study, six CYPs activities were quantitatively determined in microsomes of liver (RLMs), kidney (RRMs) and intestine (RIMs) from rats with colitis at acute (5% DSS for 7 days, UCA) and remission (7-day DSS treatment followed by 7-day cessation, UCR) phases and compared with normal rats. Generally, CYPs activities varied with isoform, organ, and disease status. Hepatic CYP1A2, 2B1, 2C6/11, 2E1 and 3A1/2 activities were reduced by acute colitis and completely or partially restored after DSS was halted. Although DSS treatment decreased the Vmax of renal CYP2C6/11 and increased that of CYP2D2, their CLint, in vitro were comparable among normal, acute and remission stages. DSS treatment changed the kinetics of CYP3A1/2-mediated nifedipine metabolism in RRMs from biphasic to classical kinetics. Notably, CYP2D2 activity was elevated in liver and kidney in acute UC, while enhanced in liver and decreased in kidney in remission. In intestine, CYP3A1/2 activity was increased in UCA and further enhanced after DSS withdrawal. These findings highlight the necessity of quantifying enzyme activity for precision drug therapy. Copyright © 2017 Elsevier B.V. All rights reserved.

  2. Changes in cytochrome P450 gene expression and enzyme activity induced by xenobiotics in rabbits in vivo and in vitro

    Directory of Open Access Journals (Sweden)

    Orsolya Palócz

    2017-06-01

    Full Text Available As considerable inter-species differences exist in xenobiotic metabolism, developing new pharmaceutical therapies for use in different species is fraught with difficulties. For this reason, very few medicines have been registered for use in rabbits, despite their importance in inter alia meat and fur production. We have developed a rapid and sensitive screening system for drug safety in rabbits based on cytochrome P450 enzyme assays, specifically CYP1A1, CYP1A2 and CYP3A6, employing an adaptation of the luciferin-based clinical assay currently used in human drug screening. Short-term (4-h cultured rabbit primary hepatocytes were treated with a cytochrome inducer (phenobarbital and 2 inhibitors (alpha-naphthoflavone and ketoconazole. In parallel, and to provide verification, New Zealand white rabbits were dosed with 80 mg/kg phenobarbital or 40 mg/kg ketoconazole for 3 d. Ketoconazole significantly increased CYP3A6 gene expression and decreased CYP3A6 activity both in vitro and in vivo. CYP1A1 activity was decreased by ketoconazole in vitro and increased in vivo. This is the first report of the inducer effect of ketoconazole on rabbit cytochrome isoenzymes in vivo. Our data support the use of a luciferin-based assay in short-term primary hepatocytes as an appropriate tool for xenobiotic metabolism assays and short-term toxicity testing in rabbits.

  3. Effect of vanillin and ethyl vanillin on cytochrome P450 activity in vitro and in vivo.

    Science.gov (United States)

    Chen, Xiao-min; Wei, Min; Zhang, Hai-mou; Luo, Cheng-hao; Chen, Yi-kun; Chen, Yong

    2012-06-01

    Food safety is of extreme importance to human health. Vanillin and ethyl vanillin are the widely used food additives and spices in foods, beverages, cosmetics and drugs. The objective of the present work was to evaluate the impact of vanillin and ethyl vanillin on the activities of CYP2C9, CYP2E1, CYP3A4, CYP2B6 and CYP1A2 in human liver microsomes (HLM) in vitro, and impact on the activities of CYP1A2, CYP2C, CYP3A and CYP2E1 in rat liver microsomes (RLM) in vivo. The in vitro results demonstrated that vanillin and ethyl vanillin had no significant effect on the activity of five human CYP450 enzymes with concentration ranged from 8 to 128 μM. However, after rats were orally administered vanillin or ethyl vanillin once a day for seven consecutive days, CYP2E1 activity was increased and CYP1A2 activity was decreased in RLM. The in vivo results revealed that drug interaction between vanillin/ethyl vanillin and the CYP2E1/CYP1A2-metabolizing drugs might be possible, and also suggested that the application of the above additives in foods and drugs should not be unlimited so as to avoid the adverse interaction.

  4. Gene expression profiling of cytochromes P450, ABC transporters and their principal transcription factors in the amygdala and prefrontal cortex of alcoholics, smokers and drug-free controls by qRT-PCR.

    Science.gov (United States)

    Toselli, Francesca; de Waziers, Isabelle; Dutheil, Mary; Vincent, Marc; Wilce, Peter A; Dodd, Peter R; Beaune, Philippe; Loriot, Marie-Anne; Gillam, Elizabeth M J

    2015-01-01

    1. Ethanol consumption and smoking alter the expression of certain drug-metabolizing enzymes and transporters, potentially influencing the tissue-specific effects of xenobiotics. 2. Amygdala (AMG) and prefrontal cortex (PFC) are brain regions that modulate the effects of alcohol and smoking, yet little is known about the expression of cytochrome P450 enzymes (P450s) and ATP-binding cassette (ABC) transporters in these tissues. 3. Here, we describe the first study on the expression of 19 P450s, their redox partners, three ABC transporters and four related transcription factors in the AMG and PFC of smokers and alcoholics by quantitative RT-PCR. 4. CYP1A1, CYP1B1, CYP2B6, CYP2C8, CYP2C18, CYP2D6, CYP2E1, CYP2J2, CYP2S1, CYP2U1, CYP4X1, CYP46, adrenodoxin and NADPH-P450 reductase, ABCB1, ABCG2, ABCA1, and transcription factors aryl hydrocarbon receptor AhR and proliferator-activated receptor α were quantified in both areas. CYP2A6, CYP2C9, CYP2C19, CYP3A4, CYP3A5, adrenodoxin reductase and the nuclear receptors pregnane X receptor and constitutive androstane receptor were detected but below the limit of quantification. CYP1A2 and CYP2W1 were not detected. 5. Adrenodoxin expression was elevated in all case groups over controls, and smokers showed a trend toward higher CYP1A1 and CYP1B1 expression. 6. Our study shows that most xenobiotic-metabolizing P450s and associated redox partners, transporters and transcription factors are expressed in human AMG and PFC.

  5. Glucuronidation of the oxidative cytochrome P450-mediated phenolic metabolites of the endocrine disruptor pesticide: methoxychlor by human hepatic UDP-glucuronosyl transferases.

    Science.gov (United States)

    Hazai, Eszter; Gagne, Peter V; Kupfer, David

    2004-07-01

    Methoxychlor, a currently used pesticide, is a proestrogen exhibiting estrogenic activity in mammals in vivo. Methoxychlor undergoes oxidative metabolism by cytochromes P450, yielding 1,1,1-trichloro-2-(4-hydroxyphenyl)-2-(4-methoxyphenyl)ethane (mono-OH-M) and 1,1,1-trichloro-2,2-bis(4-hydroxyphenyl)ethane (bis-OH-M) as main metabolites. Since humans may be exposed to these estrogenic metabolites, which are potential substrates of UDP-glucuronosyltransferases (UGTs), their glucuronide conjugation was investigated with human liver preparations and individual UGTs. Incubation of both mono-OH-M and bis-OH-M with human liver microsomes formed monoglucuronides. The structures of the glucuronides were identified by liquid chromatography/tandem mass spectometry. Examination of cDNA-expressed recombinant human hepatic UGTs revealed that several catalyze glucuronidation of both compounds. Among the cDNA-expressed UGT1A enzymes, UGT1A9 seemed to be the main catalyst of formation of mono-OH-M-glucuronide, whereas UGT1A3 seemed to be the most active in bis-OH-M-glucuronide formation. Furthermore, the chiral selectivity of mono-OH-M glucuronidation was examined. The results of the incubation of single enantiomers generally agreed with the chiral analyses of mono-OH-M derived from the glucuronidase digestion of the glucuronides of the racemic mono-OH-M. There was a relatively slight but consistent enantioselective preference of individual UGT1A1, UGT1A3, UGT1A9, and UGT2B15 enzymes for glucuronidation of the S- over the R-mono-OH-M, whereas in human liver microsomes differences were observed among donors in generating the respective R/S-mono-OH-M ratio. Since it was previously shown that human liver microsomes demethylate methoxychlor mainly into S-mono-OH-M, the observation that UGT1A isoforms preferentially glucuronidate the S-mono-OH-M suggests a suitable mechanism for eliminating this major enantiomer. This enantiomeric preference, however, is not extended to all samples of

  6. Congener-specific metabolism and sequestration of dioxin-like compounds by cytochrome P450 1A induced in the liver of crows from Tokyo, Japan

    Energy Technology Data Exchange (ETDEWEB)

    Watanabe, M.; Iwata, H.; Tanabe, S. [Ehime Univ., Matsuyama (Japan); Yoneda, K.; Hashimoto, T. [Japan Wildlife Research Center, Tokyo (Japan)

    2004-09-15

    Jungle crow (JC; Corvus macrorhynchos) is a useful bioindicator for monitoring contaminants in urban areas, because this species is residential, occupies a same habitat as human, and feeds variety of foods including domestic waste and garbage. Therefore, JCs may accumulate environmental contaminants such as polychlorinated dibenzo-p-dioxins (PCDDs), dibenzofurans (PCDFs) and coplanar polychlorinated biphenyls (Co-PCBs), which are released by human activities. Induction of cytochrome P450 (CYP) 1A is a responsive mechanism elicited by exposure to dioxinlike compounds including PCDDs/DFs and Co-PCBs. Toxicokinetic behavior of dioxin-like compounds in organisms is controlled by excretion, metabolism and absorption. These processes are, at least partly, dependent on CYP1A expression in addition to chemical structure and number of chlorine substitution of each congener. Low chlorinated congeners such as 2378-T{sub 4}CDD, 2378- T{sub 4}CDF, 12378-P{sub 5}CDD and 33'44'-PCB were easily metabolized by CYP1A1/2 in rat liver microsomes. PCDDs/DFs accumulate in hepatic tissue to a greater extent than adipose tissue in rats and mice. Recent study using transgenic CYP1A2 knockout mice demonstrated that CYP1A2 is responsible for the sequestration of 2378-T{sub 4}CDD and 23478-P{sub 5}CDF in hepatic tissue. Therefore, CYP1A is considered as a key factor responsible for toxicokinetics of dioxin-like compounds. However, there's no comprehensive data on the contribution of CYP1A to the toxicokinetics of dioxin-like congeners in wild populations. In this study, we investigated contamination levels of PCDDs/DFs and Co-PCBs in liver and breast muscle of JCs from Tokyo, Japan, and interactions of dioxin-like congeners with hepatic CYP to elucidate congener-specific toxicokinetics related to CYP expression in JC.

  7. Cytochrome P450 genetic polymorphisms of Mexican indigenous populations.

    Science.gov (United States)

    Sosa-Macías, Martha; Llerena, Adrián

    2013-01-01

    This review focuses on the genetic polymorphisms of the cytochrome P450 (CYP) genes in Mexican indigenous populations, who are a part of the wide ethnic diversity of this country. These native groups have a particular historical trajectory that is different from the Mexican Mestizos. This variability may be reflected in the frequency distribution of polymorphisms in the CYP genes that encode enzymes involved in the metabolism of drugs and other xenobiotics. Therefore, these polymorphisms may affect drug efficacy and safety in indigenous populations in Mexico. The present study aimed to analyze the prevalence of CYP polymorphisms in indigenous Mexicans and to compare the results with studies in Mexican Mestizos. Because the extrapolation of pharmacogenetic data from Mestizos is not applicable to the majority of indigenous groups, pharmacogenetic studies directed at indigenous populations need to be developed. The Amerindians analyzed in this study showed a low phenotypic (CYP2D6) and genotypic (CYP2D6, CYP2C9) diversity, unlike Mexican Mestizos. The frequency of polymorphisms in the CYP1A1, CYP2C19, CYP2E1, and CYP3A4 genes was more similar among the Amerindians and Mexican Mestizos, with the exception of the CYP1A2 gene, whose *1F variant frequency in Mexican Amerindians was the highest described to date.

  8. Modulation of cytochrome P450 metabolism and transport across intestinal epithelial barrier by ginger biophenolics.

    Directory of Open Access Journals (Sweden)

    Rao Mukkavilli

    Full Text Available Natural and complementary therapies in conjunction with mainstream cancer care are steadily gaining popularity. Ginger extract (GE confers significant health-promoting benefits owing to complex additive and/or synergistic interactions between its bioactive constituents. Recently, we showed that preservation of natural "milieu" confers superior anticancer activity on GE over its constituent phytochemicals, 6-gingerol (6G, 8-gingerol (8 G, 10-gingerol (10 G and 6-shogaol (6S, through enterohepatic recirculation. Here we further evaluate and compare the effects of GE and its major bioactive constituents on cytochrome P450 (CYP enzyme activity in human liver microsomes by monitoring metabolites of CYP-specific substrates using LC/MS/MS detection methods. Our data demonstrate that individual gingerols are potent inhibitors of CYP isozymes, whereas GE exhibits a much higher half-maximal inhibition value, indicating no possible herb-drug interactions. However, GE's inhibition of CYP1A2 and CYP2C8 reflects additive interactions among the constituents. In addition, studies performed to evaluate transporter-mediated intestinal efflux using Caco-2 cells revealed that GE and its phenolics are not substrates of P-glycoprotein (Pgp. Intriguingly, however, 10 G and 6S were not detected in the receiver compartment, indicating possible biotransformation across the Caco-2 monolayer. These data strengthen the notion that an interplay of complex interactions among ginger phytochemicals when fed as whole extract dictates its bioactivity highlighting the importance of consuming whole foods over single agents. Our study substantiates the need for an in-depth analysis of hepatic biotransformation events and distribution profiles of GE and its active phenolics for the design of safe regimens.

  9. Modulation of cytochrome P450 metabolism and transport across intestinal epithelial barrier by ginger biophenolics.

    Science.gov (United States)

    Mukkavilli, Rao; Gundala, Sushma R; Yang, Chunhua; Donthamsetty, Shashikiran; Cantuaria, Guilherme; Jadhav, Gajanan R; Vangala, Subrahmanyam; Reid, Michelle D; Aneja, Ritu

    2014-01-01

    Natural and complementary therapies in conjunction with mainstream cancer care are steadily gaining popularity. Ginger extract (GE) confers significant health-promoting benefits owing to complex additive and/or synergistic interactions between its bioactive constituents. Recently, we showed that preservation of natural "milieu" confers superior anticancer activity on GE over its constituent phytochemicals, 6-gingerol (6G), 8-gingerol (8 G), 10-gingerol (10 G) and 6-shogaol (6S), through enterohepatic recirculation. Here we further evaluate and compare the effects of GE and its major bioactive constituents on cytochrome P450 (CYP) enzyme activity in human liver microsomes by monitoring metabolites of CYP-specific substrates using LC/MS/MS detection methods. Our data demonstrate that individual gingerols are potent inhibitors of CYP isozymes, whereas GE exhibits a much higher half-maximal inhibition value, indicating no possible herb-drug interactions. However, GE's inhibition of CYP1A2 and CYP2C8 reflects additive interactions among the constituents. In addition, studies performed to evaluate transporter-mediated intestinal efflux using Caco-2 cells revealed that GE and its phenolics are not substrates of P-glycoprotein (Pgp). Intriguingly, however, 10 G and 6S were not detected in the receiver compartment, indicating possible biotransformation across the Caco-2 monolayer. These data strengthen the notion that an interplay of complex interactions among ginger phytochemicals when fed as whole extract dictates its bioactivity highlighting the importance of consuming whole foods over single agents. Our study substantiates the need for an in-depth analysis of hepatic biotransformation events and distribution profiles of GE and its active phenolics for the design of safe regimens.

  10. Optimization of heme precursors for the expression of human cytochrome P450 2A13 and its co-expression with oxidoreductase in baculovirus/sf9 system.

    Science.gov (United States)

    Lu, Hui-Yuan; Qiu, Liang-Lin; Yang, Xue-Jiao; Zhang, Xiao-Ming; Zhang, Zhan; Wang, Shou-Lin

    2013-06-01

    Human cytochrome P450 2A13 (CYP2A13), mainly expressed in respiratory tract, is active towards numerous toxicants. To establish the metabolism in vitro, we expressed CYP2A13 and NADPH-CYP450 oxidoreductase (POR) in a baculovirus/sf9 system. Due to the deficiency of sf9 cells in heme incorporation, we investigated the effects of different heme precursors on the expression of CYP2A13, POR and their co-expression. The present results showed that both CYP2A13 and POR were presented the highest expression levels or activity with 0.2 mM δ-aminolaevulinic acid (5-ALA), 0.02 mM Fe(3+) and 0.5-1.0 μg/ml hemin. The combination of 0.2 mM 5-ALA and 0.02 mM Fe(3+) significantly improved CYP2A13 expression and content compared with heme precursors alone, so was POR activity. A multiplicity of infection (MOI) value of 5 pfu/cell for CYP2A13 baculovirus particles induced very high CYP2A13 expression. When co-infected with different POR MOI values, a viral ratio of 5 : 2 was associated with the highest CYP2A13 activity, whereas POR activity dose dependently increased with POR MOI. Furthermore, the expressed CYP2A13 in the optimized conduction could eliminate its substrate aflatoxin B1 at a significantly higher than those in other condition (P < 0.01). Our results provide an efficient approach for expressing functionally characterized, highly active and homogeneous CYP2A13 proteins.

  11. Inhibition of human cytochrome p450 2c8-catalyzed amodiaquine n-desethylation: Effect of five traditionally and commonly used herbs

    Directory of Open Access Journals (Sweden)

    Yasotha Devi Muthiah

    2016-01-01

    Full Text Available Background: In Southeast Asia and many parts of the world, herbal products are increasingly used in parallel with modern medicine. Objective: This study aimed to investigate the effects of herbs commonly used in Southeast Asia on activity of cytochrome P450 2C8 (CYP2C8, an important human hepatic enzyme in drug metabolism. Materials and Methods: The selected herbs, such as Eurycoma longifolia Jack (ELJ, Labisia pumila (LP, Echinacea purpurea (EP, Andrographis paniculata (AP, and Ginkgo biloba (GB, were subjected to inhibition studies using an in vitro CYP2C8 activity marker, amodiaquine N-desethylase assay. Inhibition parameters, inhibitory concentration 50% (IC50, and Kivalues were determined to study the potency and mode of inhibition. Results: All herbs inhibited CYP2C8 with the following order of potency: LP > ELJ > GB > AP > EP. LP and ELJ inhibited potently at Ki's of 2 and 4 times the Kiof quercetin, the positive control. The inhibition by LP was uncompetitive in nature as compared to competitive or mixed type inhibition observed with other herbs. GB exhibited moderate inhibitory effect at a Ki6 times larger than quercetin Ki. AP and EP, on the other hand, showed only weak inhibition. Conclusion: The herbs we chose represented the more commonly used herbs in Southeast Asia where collision of tradition and modernization in healthcare, if not properly managed, may lead to therapeutic misadventures. We conclude that concurrent consumption of some herbs, in particular, LP and ELJ, may have relevance in drug-herb interactions via CYP2C8 inhibition in vivo.

  12. Oxidation of N-Nitrosoalkylamines by human cytochrome P450 2A6: sequential oxidation to aldehydes and carboxylic acids and analysis of reaction steps.

    Science.gov (United States)

    Chowdhury, Goutam; Calcutt, M Wade; Guengerich, F Peter

    2010-03-12

    Cytochrome P450 (P450) 2A6 activates nitrosamines, including N,N-dimethylnitrosamine (DMN) and N,N-diethylnitrosamine (DEN), to alkyl diazohydroxides (which are DNA-alkylating agents) and also aldehydes (HCHO from DMN and CH(3)CHO from DEN). The N-dealkylation of DMN had a high intrinsic kinetic deuterium isotope effect ((D)k(app) approximately 10), which was highly expressed in a variety of competitive and non-competitive experiments. The (D)k(app) for DEN was approximately 3 and not expressed in non-competitive experiments. DMN and DEN were also oxidized to HCO(2)H and CH(3)CO(2)H, respectively. In neither case was a lag observed, which was unexpected considering the k(cat) and K(m) parameters measured for oxidation of DMN and DEN to the aldehydes and for oxidation of the aldehydes to the carboxylic acids. Spectral analysis did not indicate strong affinity of the aldehydes for P450 2A6, but pulse-chase experiments showed only limited exchange with added (unlabeled) aldehydes in the oxidations of DMN and DEN to carboxylic acids. Substoichiometric kinetic bursts were observed in the pre-steady-state oxidations of DMN and DEN to aldehydes. A minimal kinetic model was developed that was consistent with all of the observed phenomena and involves a conformational change of P450 2A6 following substrate binding, equilibrium of the P450-substrate complex with a non-productive form, and oxidation of the aldehydes to carboxylic acids in a process that avoids relaxation of the conformation following the first oxidation (i.e. of DMN or DEN to an aldehyde).

  13. Systemic uptake of miconazole during vaginal suppository use and effect on CYP1A2 and CYP3A4 associated enzyme activities in women

    DEFF Research Database (Denmark)

    Kjærstad, Mia Birkhøj; Nielsen, Flemming; Nøhr-Jensen, Lene

    2010-01-01

    To investigate if the ordinary use of a vaginal suppository containing miconazole results in systemic absorption that is sufficient to affect the activities of CYP1A2 and CYP3A4, which are major drug- and steroid-metabolising enzymes.......To investigate if the ordinary use of a vaginal suppository containing miconazole results in systemic absorption that is sufficient to affect the activities of CYP1A2 and CYP3A4, which are major drug- and steroid-metabolising enzymes....

  14. Cytochrome P450 (CYP450) Tests

    Science.gov (United States)

    Tests and Procedures Cytochrome P450 (CYP450) tests By Mayo Clinic Staff Your doctor may use cytochrome P450 (CYP450) tests to help determine how your ... find the right antidepressant. Genotyping tests, such as cytochrome P450 tests, may speed up the identification of ...

  15. CYP2J2 and CYP2C19 are the major enzymes responsible for metabolism of albendazole and fenbendazole in human liver microsomes and recombinant P450 assay systems.

    Science.gov (United States)

    Wu, Zhexue; Lee, Doohyun; Joo, Jeongmin; Shin, Jung-Hoon; Kang, Wonku; Oh, Sangtaek; Lee, Do Yup; Lee, Su-Jun; Yea, Sung Su; Lee, Hye Suk; Lee, Taeho; Liu, Kwang-Hyeon

    2013-11-01

    Albendazole and fenbendazole are broad-spectrum anthelmintics that undergo extensive metabolism to form hydroxyl and sulfoxide metabolites. Although CYP3A and flavin-containing monooxygenase have been implicated in sulfoxide metabolite formation, the enzymes responsible for hydroxyl metabolite formation have not been identified. In this study, we used human liver microsomes and recombinant cytochrome P450s (P450s) to characterize the enzymes involved in the formation of hydroxyalbendazole and hydroxyfenbendazole from albendazole and fenbendazole, respectively. Of the 10 recombinant P450s, CYP2J2 and/or CYP2C19 was the predominant enzyme catalyzing the hydroxylation of albendazole and fenbendazole. Albendazole hydroxylation to hydroxyalbendazole is primarily mediated by CYP2J2 (0.34 μl/min/pmol P450, which is a rate 3.9- and 8.1-fold higher than the rates for CYP2C19 and CYP2E1, respectively), whereas CYP2C19 and CYP2J2 contributed to the formation of hydroxyfenbendazole from fenbendazole (2.68 and 1.94 μl/min/pmol P450 for CYP2C19 and CYP2J2, respectively, which are rates 11.7- and 8.4-fold higher than the rate for CYP2D6). Correlation analysis between the known P450 enzyme activities and the rate of hydroxyalbendazole and hydroxyfenbendazole formation in samples from 14 human liver microsomes showed that albendazole hydroxylation correlates with CYP2J2 activity and fenbendazole hydroxylation correlates with CYP2C19 and CYP2J2 activities. These findings were supported by a P450 isoform-selective inhibition study in human liver microsomes. In conclusion, our data for the first time suggest that albendazole hydroxylation is primarily catalyzed by CYP2J2, whereas fenbendazole hydroxylation is preferentially catalyzed by CYP2C19 and CYP2J2. The present data will be useful in understanding the pharmacokinetics and drug interactions of albendazole and fenbendazole in vivo.

  16. A simple chromatographic method for determining norfloxacin and enoxacin in pharmacokinetic study assessing CYP1A2 inhibition.

    Science.gov (United States)

    Kobayashi, Toshimi; Homma, Masato; Momo, Kenji; Kobayashi, Daisuke; Kohda, Yukinao

    2011-04-01

    We developed a simple assay method for the determination of serum and urine norfloxacin and enoxacin using reversed-phase high-performance liquid chromatography and perchloric acid precipitation for sample pre-treatment. Optimized conditions can permit detection of norfloxacin and enoxacin in the same chromatogram, so either compound can be used as an internal standard for another determinant. Supernatants of the precipitated samples were analyzed by the octadecylsilyl silica-gel column under ambient temperature and an ultraviolet wavelength of 272  nm. A mobile phase solvent consisting of 20 mm sodium dihydrogenphosphate (pH 3.0) and acetonitrile (85:15, v/v) was pumped at a flow rate of 1.0 mL/min. The calibration curves for norfloxacin and enoxacin at a concentration of 62.5-1000 ng/mL for serum and 250-4000 ng/mL for urine were linear (r > 0.9997). The recoveries of norfloxacin and enoxacin from serum and urine were >94% with the coefficient of variations (CV) <5%. The CVs for intra- and inter-day assay of norfloxacin and enoxacin were <4.2 and <5.5%, respectively. This method can be applied to the pharmacokinetic study of norfloxacin and enoxacin after repeated administration to assess changes in CYP1A2 activity in healthy subjects. Copyright © 2010 John Wiley & Sons, Ltd.

  17. Expression of albumin and cytochrome P450 enzymes in HepG2 cells cultured with a nanotechnology-based culture plate with microfabricated scaffold.

    Science.gov (United States)

    Nakamura, Kazuaki; Kato, Natsuko; Aizawa, Kazuko; Mizutani, Reiko; Yamauchi, Junji; Tanoue, Akito

    2011-10-01

    The Nanoculture plate (NCP) is a recently developed plate which essentially consists of a textured surface with specific characteristics that induce spheroid formation: microfabrications with a micro-square pattern on the culture surface. The NCP can be used to generate uniform adhesive spheroids of cancer cell lines using conventional techniques without the need of any animal compounds. In this study, we assessed the performance of human hepatoma cell line HepG2 cells cultured with an NCP to evaluate the effects of the NCP on their hepatocyte-specific functions. The NCP facilitated the formation of three-dimensional (3D) HepG2 cell architecture. HepG2 cells cultured with an NCP exhibited enhanced mRNA expression levels of albumin and cytochrome P450 (CYP) enzymes compared to those cultured with a two-dimensional (2D) conventional plate. The expression levels of two specific liver-enriched transcription factors, hepatocyte nuclear factor 4α (HNF4α) and CCAAT/enhancer binding protein α (C/EBPα), were higher in HepG2 cells grown with the NCP than those in HepG2 cells grown with conventional plates before albumin and CYP enzymes expression levels were increased. The inducibility of CYP1A2 and CYP3A4 mRNA following exposure to inducers in HepG2 cells cultured with an NCP was comparable to that in HepG2 cells cultured with conventional plates, while the expression levels of CYP1A2 and CYP3A4 mRNA following exposure to inducers were higher when using an NCP than when using conventional plates. These results suggest that the use of an NCP enhances the hepatocyte-specific functions of HepG2 cells, such as drug-metabolizing enzyme expression, making the NCP/HepG2 system a useful tool for evaluating drug metabolism in vitro.

  18. Investigation on Modulation of Human Cytochrome P450 and P-glycoprotein by Herb or Natural Product Using in Vivo Probe Substrate%利用体内探针法考察植物药和天然产物对人体细胞色素P450和P-糖蛋白活性的影响

    Institute of Scientific and Technical Information of China (English)

    叶蓁; 朱玲玲; 周权

    2012-01-01

    OBJECTIVE To promote the in vivo investigation on modulation of human cytochrome P450 and P-glycoprotein by herb or natural product, anticipate clinical drug interaction and improve rational drug use. METHODS Literatures using in vivo probe substrate were reviewed. RESULTS Research in this respect abroad is hot. Cocktail methods are widely used. CONCLIS1ONS In vivo probe substrate phenorying studies should be paid more attention in investigation on modulation of CYP and P-gp by herb and natural products.%目的 促进植物药和天然产物对人体细胞色素P450和P-糖蛋白活性影响的人体研究的深入,预期临床相互作用,提高合理用药水平.方法 综述体内探针法在该领域的国内外的应用.详细介绍应用方法和注意事项.结果 国外利用体内探针法的研究较热.鸡尾酒探针法的应用已成熟.结论 在我国应大力支持和推广体内探针法在新药研发和临床应用中的研究.

  19. [Preclinical investigation of pharmaceuticals impact against cytochrome P450 activity and prognosis of substrate affinity as means for providing substrate therapy safety].

    Science.gov (United States)

    Fomin, E V; Baĭchorov, I Kh; Shikh, E V; Sizova, Zh M

    2013-01-01

    Tricyclic antidepressants, not influencing the P450 3A4 activity, are safe in combination with drugs of other groups used in the treatment of comorbid patients. Azaphen is is one of the agents most widely used in the clinical practice. The in vitro electrochemical analysis showed that pipofezin (azaphen) was not a substrate, inductor, and/or inhibitor of cytochrome P450 CYP3A4 isoenzymes. The Guzar programme computer modelling and the literature data demonstrated the substrate affinity of pipifezin to CYP1A2.

  20. Molecular Lego: design of molecular assemblies of P450 enzymes for nanobiotechnology.

    Science.gov (United States)

    Gilardi, Gianfranco; Meharenna, Yergalem T; Tsotsou, Georgia E; Sadeghi, Sheila J; Fairhead, Michael; Giannini, Silva

    2002-01-01

    This paper reports on the application of the molecular Lego approach to P450 enzymes. Protein domains are used as catalytic (P450 BM3 haem domain and human P450 2E1) or electron transfer (flavodoxin and P450 BM3 reductase) modules. The objectives are to build assemblies with improved electrochemical properties, to construct soluble human P450 enzymes, and to generate libraries of new P450 catalytic modules based on P450 BM3. A rationally designed, gene-fused assembly (BMP-FLD) was obtained from the soluble haem domain of cytochrome P450 BM3 from Bacillus megaterium (BMP) and flavodoxin from Desulfovibrio vulgaris (FLD). The assembly was expressed successfully and characterised in its active form, displaying improved electrochemical properties. Solubilisation of the human, membrane-bound P450 2E1 (2E1) was achieved by fusing key elements of the 2E1 enzyme with selected parts of P450 BM3. An assembly containing the first 54 residues of P450 BM3, the whole sequence of P450 2E1 from residue 81 and the reductase domain of P450 BM3 was constructed. The 2E1-BM3 assembly was successfully expressed in the cytosol of Escherichia coli. The soluble form of 2E1-BM3 was reduced in carbon monoxide atmosphere and displayed the typical absorption peak at 450 nm, characteristic of a folded and active P450 enzyme. Finally, the alkali method previously developed in this laboratory was used to screen for P450 activity within a library of random mutants of P450 BM3. A number of variants active towards non-physiological substrates, such as pesticides and polyaromatic hydrocarbons were identified, providing new P450 catalytic modules. The combination of these three areas of research provide interesting tools for exploitation in nanobiotechnology.

  1. Traditional herbal formulas to as treatments for musculoskeletal disorders: Their inhibitory effects on the activities of human microsomal cytochrome p450s and udp-glucuronosyltransferases

    Directory of Open Access Journals (Sweden)

    Seong Eun Jin

    2016-01-01

    Abbreviation used: BPTSS: Bangpungtongseong-san, OJS: Ojeok-san, OYSGS: Oyaksungi-san, CYP450s: cytochrome P450s, UGTs: UDP-glucuronosyltransferases, MSDs: Musculoskeletal disorders, NSAIDs: nonsteroidal anti-inflammatory drugs, EOMCC: 7-ethoxy-methyloxy-3-cyanocoumarin, DBOMF: di(benzyloxymethoxyfluorescein, BOMCC: 7-benzyloxy-4-trifluoromethylcoumarin, HPLC: High-performance liquid chromatography, PDA: photo diode array, SEM: standard error of the mean, UDPGA: uridine 5'-diphosphoglucuronic acid.

  2. Altered CYP19A1 and CYP3A4 Activities Due to Mutations A115V, T142A, Q153R and P284L in the Human P450 Oxidoreductase

    Directory of Open Access Journals (Sweden)

    Sameer S. Udhane

    2017-08-01

    Full Text Available All cytochromes P450s in the endoplasmic reticulum rely on P450 oxidoreductase (POR for their catalytic activities. Mutations in POR cause metabolic disorders of steroid hormone biosynthesis and affect certain drug metabolizing P450 activities. We studied mutations A115V, T142A, Q153R identified in the flavin mononucleotide (FMN binding domain of POR that interacts with partner proteins and P284L located in the hinge region that is required for flexibility and domain movements in POR. Human wild-type (WT and mutant POR as well as CYP3A4 and CYP19A1 proteins in recombinant form were expressed in bacteria, and purified proteins were reconstituted in liposomes for enzyme kinetic assays. Quality of POR protein was checked by cytochrome c reduction assay as well as flavin content measurements. We found that proteins carrying mutations A115V, T142A located close to the FMN binding site had reduced flavin content compared to WT POR and lost almost all activity to metabolize androstenedione via CYP19A1 and showed reduced CYP3A4 activity. The variant P284L identified from apparently normal subjects also had severe loss of both CYP19A1 and CYP3A4 activities, indicating this to be a potentially disease causing mutation. The mutation Q153R initially identified in a patient with disordered steroidogenesis showed remarkably increased activities of both CYP19A1 and CYP3A4 without any significant change in flavin content, indicating improved protein–protein interactions between POR Q153R and some P450 proteins. These results indicate that effects of mutations on activities of individual cytochromes P450 can be variable and a detailed analysis of each variant with different partner proteins is necessary to accurately determine the genotype-phenotype correlations of POR variants.

  3. [Clinical survey of tizanidine-induced adverse effects--impact of concomitant drugs providing cytochrome P450 1A2 modification--].

    Science.gov (United States)

    Momo, Kenji; Homma, Masato; Matsumoto, Sayaka; Sasaki, Tadanori; Kohda, Yukinao

    2013-01-01

    The drug-drug interactions of tizanidine and cytochrome (CYP) P450 1A2 inhibitors, which potentially alter the hepatic metabolism of tizanidine, were investigated by retrospective survey of medical records with regard to prescription. One thousand five hundred sixty-three patients treated with tizanidine at University of Tsukuba Hospital were investigated. Of those, 713 patients (45.6%) were treated with coadministration of tizanidine and CYP1A2 inhibitors (37 drugs). The patients who received a combination of tizanidine and CYP1A2 inhibitors were characterized as elderly, having multiple diseases, and taking a large number of comedications (over 10 drugs) for a long period as compared with the patients who did not receive CYP1A2 inhibitors. Tizanidine-induced adverse effects were examined in 100 patients treated with coadministration of tizanidine and 8 CYP1A2 inhibitors. Adverse effects (e.g., drowsiness: 10 patients; low blood pressure: 9 patients; low heart rate: 9 patients) were observed in 23 patients (23%) 8±10 days after CYP1A2 inhibitors were coadministered. The patients with tizanidine-induced adverse effects were of older age (64.3±9.8 vs. 57.5±18.1 years, p<0.05) and received a higher daily dose of tizanidine (3.00±0.74 vs. 2.56±0.86 mg/day, p<0.05) than the patients without adverse effects. The present results suggest that coadministration of tizanidine and CYP1A2 inhibitors enhances tizanidine-induced adverse effects, especially in elderly patients treated with a higher dose of tizanidine.

  4. Coffee and tea consumption, genotype-based CYP1A2 and NAT2 activity and colorectal cancer risk—Results from the EPIC cohort study

    NARCIS (Netherlands)

    Dik, V.K.; Bueno-de-Mesquita, H.B.; Oijen, van M.G.C.T.; Siersema, P.D.; Uiterwaal, C.S.P.M.; Gils, van C.H.; Duijnhoven, van F.J.B.

    2014-01-01

    Coffee and tea contain numerous antimutagenic and antioxidant components and high levels of caffeine that may protect against colorectal cancer (CRC). We investigated the association between coffee and tea consumption and CRC risk and studied potential effect modification by CYP1A2 and NAT2

  5. Coffee and tea consumption, genotype-based CYP1A2 and NAT2 activity and colorectal cancer risk—Results from the EPIC cohort study

    NARCIS (Netherlands)

    Dik, V.K.; Bueno-de-Mesquita, H.B.; Oijen, van M.G.C.T.; Siersema, P.D.; Uiterwaal, C.S.P.M.; Gils, van C.H.; Duijnhoven, van F.J.B.

    2014-01-01

    Coffee and tea contain numerous antimutagenic and antioxidant components and high levels of caffeine that may protect against colorectal cancer (CRC). We investigated the association between coffee and tea consumption and CRC risk and studied potential effect modification by CYP1A2 and NAT2 genotype

  6. Systemic uptake of miconazole during vaginal suppository use and effect on CYP1A2 and CYP3A4 associated enzyme activities in women

    DEFF Research Database (Denmark)

    Kjærstad, Mia Birkhøj; Nielsen, Flemming; Nøhr-Jensen, Lene;

    2010-01-01

    To investigate if the ordinary use of a vaginal suppository containing miconazole results in systemic absorption that is sufficient to affect the activities of CYP1A2 and CYP3A4, which are major drug- and steroid-metabolising enzymes....

  7. 7,12-Dimethylbenzanthracene induces apoptosis in RL95-2 human endometrial cancer cells: Ligand-selective activation of cytochrome P450 1B1

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Ji Young [Department of Anatomy and Cell Biology, College of Medicine, Dong-A University, Busan 602-714 (Korea, Republic of); Medical Research Science Center, Dong-A University, Busan 602-714 (Korea, Republic of); Lee, Seung Gee [Department of Anatomy and Cell Biology, College of Medicine, Dong-A University, Busan 602-714 (Korea, Republic of); Mitochondria Hub Regulation Center, Dong-A University, Busan 602-714 (Korea, Republic of); Chung, Jin-Yong [Department of Anatomy and Cell Biology, College of Medicine, Dong-A University, Busan 602-714 (Korea, Republic of); Medical Research Science Center, Dong-A University, Busan 602-714 (Korea, Republic of); Kim, Yoon-Jae [Department of Anatomy and Cell Biology, College of Medicine, Dong-A University, Busan 602-714 (Korea, Republic of); Mitochondria Hub Regulation Center, Dong-A University, Busan 602-714 (Korea, Republic of); Park, Ji-Eun [Department of Anatomy and Cell Biology, College of Medicine, Dong-A University, Busan 602-714 (Korea, Republic of); Medical Research Science Center, Dong-A University, Busan 602-714 (Korea, Republic of); Oh, Seunghoon [Department of Physiology, College of Medicine, Dankook University, Cheonan 330-714 (Korea, Republic of); Lee, Se Yong [Department of Obstetrics and Gynecology, Busan Medical Center, Busan 611-072 (Korea, Republic of); Choi, Hong Jo [Department of General Surgery, College of Medicine, Dong-A University, Busan 602-714 (Korea, Republic of); Yoo, Young Hyun, E-mail: yhyoo@dau.ac.kr [Department of Anatomy and Cell Biology, College of Medicine, Dong-A University, Busan 602-714 (Korea, Republic of); Mitochondria Hub Regulation Center, Dong-A University, Busan 602-714 (Korea, Republic of); Medical Research Science Center, Dong-A University, Busan 602-714 (Korea, Republic of); and others

    2012-04-15

    7,12-Dimethylbenzanthracene (DMBA), a polycyclic aromatic hydrocarbon, exhibits mutagenic, carcinogenic, immunosuppressive, and apoptogenic properties in various cell types. To achieve these functions effectively, DMBA is modified to its active form by cytochrome P450 1 (CYP1). Exposure to DMBA causes cytotoxicity-mediated apoptosis in bone marrow B cells and ovarian cells. Although uterine endometrium constitutively expresses CYP1A1 and CYP1B1, their apoptotic role after exposure to DMBA remains to be elucidated. Therefore, we chose RL95-2 endometrial cancer cells as a model system for studying DMBA-induced cytotoxicity and cell death and hypothesized that exposure to DMBA causes apoptosis in this cell type following CYP1A1 and/or CYP1B1 activation. We showed that DMBA-induced apoptosis in RL95-2 cells is associated with activation of caspases. In addition, mitochondrial changes, including decrease in mitochondrial potential and release of mitochondrial cytochrome c into the cytosol, support the hypothesis that a mitochondrial pathway is involved in DMBA-induced apoptosis. Exposure to DMBA upregulated the expression of AhR, Arnt, CYP1A1, and CYP1B1 significantly; this may be necessary for the conversion of DMBA to DMBA-3,4-diol-1,2-epoxide (DMBA-DE). Although both CYP1A1 and CYP1B1 were significantly upregulated by DMBA, only CYP1B1 exhibited activity. Moreover, knockdown of CYP1B1 abolished DMBA-induced apoptosis in RL95-2 cells. Our data show that RL95-2 cells are susceptible to apoptosis by exposure to DMBA and that CYP1B1 plays a pivotal role in DMBA-induced apoptosis in this system. -- Highlights: ► Cytotoxicity-mediated apoptogenic action of DMBA in human endometrial cancer cells. ► Mitochondrial pathway in DMBA-induced apoptosis of RL95-2 endometrial cancer cells. ► Requirement of ligand-selective activation of CYP1B1 in DMBA-induced apoptosis.

  8. Size- and time-dependent alteration in metabolic activities of human hepatic cytochrome P450 isozymes by gold nanoparticles via microsomal coincubations

    Science.gov (United States)

    Ye, Meiling; Tang, Ling; Luo, Mengjun; Zhou, Jing; Guo, Bin; Liu, Yangyuan; Chen, Bo

    2014-11-01

    Nano-sized particles are known to interfere with drug-metabolizing cytochrome P450 (CYP) enzymes, which can be anticipated to be a potential source of unintended adverse reactions, but the mechanisms underlying the inhibition are still not well understood. Herein we report a systematic investigation of the impacts of gold nanoparticles (AuNPs) on five major CYP isozymes under in vitro incubations of human liver microsomes (HLMs) with tannic acid (TA)-stabilized AuNPs in the size range of 5 to 100 nm. It is found that smaller AuNPs show more pronounced inhibitory effects on CYP2C9, CYP2C19, CYP2D6, and CYP3A4 in a dose-dependent manner, while 1A2 is the least susceptible to the AuNP inhibition. The size- and dose-dependent CYP-specific inhibition and the nonspecific drug-nanogold binding in the coincubation media can be significantly reduced by increasing the concentration ratio of microsomal proteins to AuNPs, probably via a noncompetitive mode. Remarkably, AuNPs are also found to exhibit a slow time-dependent inactivation of 2D6 and 3A4 in a β-nicotinamide adenine dinucleotide 2'-phosphate reduced tetrasodium salt hydrate (NADPH)-independent manner. During microsomal incubations, UV-vis spectroscopy, dynamic light scattering, and zeta-potential measurements were used to monitor the changes in particle properties under the miscellaneous AuNP/HLM/CYP dispersion system. An improved stability of AuNPs by mixing HLM with the gold nanocolloid reveals that the stabilization via AuNP-HLM interactions may occur on a faster time scale than the salt-induced nanoaggregation by incubation in phosphate buffer. The results suggest that the AuNP induced CYP inhibition can be partially attributed to its adhesion onto the enzymes to alter their structural conformations or onto the HLM membrane therefore impairing the integral membrane proteins. Additionally, AuNPs likely block the substrate pocket on the CYP surface, depending on both the particle characteristics and the

  9. Cytochromes P450 are Expressed in Proliferating Cells in Barrett's Metaplasia

    Directory of Open Access Journals (Sweden)

    Steven J. Hughes

    1999-06-01

    Full Text Available The expression of cytochromes P450 (CYP in Barrett's esophagus and esophageal squamous mucosa was investigated. Esophagectomy specimens from 23 patients were examined for CYP expression of CYP1A2, CYP3A4, CYP2C9/10, and CYP2E1 by immunohistochemical analysis, and the expression of CYP1A1, CYP3A4, CYP1B1, CYP2E1, and CYP2C9/10 in these tissues was further confirmed by reverse transcription polymerase chain reaction. Immunohistochemical analysis of esophageal squamous mucosa (n = 12 showed expression of CYP1A2, CYP3A4, CYP2E1, and CYP2C9/10 proteins, but it was noted that cells within the basal proliferative zone did not express CYPs. Immunohistochemical analysis of Barrett's esophagus (n = 13 showed expression of CYP1A2, CYP3A4, CYP2E1, and CYP2C9/10 that was prominent in the basal glandular regions, which are areas containing a high percentage of actively proliferating cells. Immunohistochemical staining for both proliferating cell nuclear antigen and the CYPs further supported the colocalization of CYP expression to areas of active cell proliferation in Barrett's esophagus, whereas in the esophageal squamous epithelium, CYP expression is limited to cells that are not proliferating. RT-PCR with amplification product sequence analysis confirmed CYP1A1, CYP3A4, CYP1B1, CYP2E1, and CYP2C9/10 mRNA expression in Barrett's esophagus. These data suggest that the potential ability of cells in Barrett's esophagus to both activate carcinogens and proliferate may be important risk factors affecting carcinogenesis in this metaplastic tissue.

  10. Cytochromes P450 are expressed in proliferating cells in Barrett's metaplasia.

    Science.gov (United States)

    Hughes, S J; Morse, M A; Weghorst, C M; Kim, H; Watkins, P B; Guengerich, F P; Orringer, M B; Beer, D G

    1999-06-01

    The expression of cytochromes P450 (CYP) in Barrett's esophagus and esophageal squamous mucosa was investigated. Esophagectomy specimens from 23 patients were examined for CYP expression of CYP1A2, CYP3A4, CYP2C9/10, and CYP2E1 by immunohistochemical analysis, and the expression of CYP1A1, CYP3A4, CYP1B1, CYP2E1, and CYP2C9/10 in these tissues was further confirmed by reverse transcription polymerase chain reaction. Immunohistochemical analysis of esophageal squamous mucosa (n = 12) showed expression of CYP1A2, CYP3A4, CYP2E1, and CYP2C9/10 proteins, but it was noted that cells within the basal proliferative zone did not express CYPs. Immunohistochemical analysis of Barrett's esophagus (n = 13) showed expression of CYP1A2, CYP3A4, CYP2E1, and CYP2C9/10 that was prominent in the basal glandular regions, which are areas containing a high percentage of actively proliferating cells. Immunohistochemical staining for both proliferating cell nuclear antigen and the CYPs further supported the colocalization of CYP expression to areas of active cell proliferation in Barrett's esophagus, whereas in the esophageal squamous epithelium, CYP expression is limited to cells that are not proliferating. RT-PCR with amplification product sequence analysis confirmed CYP1A1, CYP3A4, CYP1B1, CYP2E1, and CYP2C9/10 mRNA expression in Barrett's esophagus. These data suggest that the potential ability of cells in Barrett's esophagus to both activate carcinogens and proliferate may be important risk factors affecting carcinogenesis in this metaplastic tissue.

  11. The effects of acute hydrogen sulfide poisoning on cytochrome P450 isoforms activity in rats.

    Science.gov (United States)

    Wang, Xianqin; Chen, Mengchun; Chen, Xinxin; Ma, Jianshe; Wen, Congcong; Pan, Jianchun; Hu, Lufeng; Lin, Guanyang

    2014-01-01

    Hydrogen sulfide (H2S) is the second leading cause of toxin related death (after carbon monoxide) in the workplace. H2S is absorbed by the upper respiratory tract mucosa, and it causes histotoxic hypoxemia and respiratory depression. Cocktail method was used to evaluate the influences of acute H2S poisoning on the activities of cytochrome P450 isoforms CYP2B6, CYP2D6, CYP3A4, CYP1A2, CYP2C19, and CYP2C9, which were reflected by the changes of pharmacokinetic parameters of six specific probe drugs, bupropion, metoprolol, midazolam, phenacetin, omeprazole, and tolbutamide, respectively. The experimental rats were randomly divided into two groups, control group and acute H2S poisoning group (inhaling 300 ppm for 2 h). The mixture of six probes was given to rats by oral administration and the blood samples were obtained at a series of time points through the caudal vein. The concentrations of probe drugs in rat plasma were measured by LC-MS. The results for acute H2S poisoning and control groups were as follows: there was a statistically significant difference in the AUC and C max for bupropion, metoprolol, phenacetin, and tolbutamide, while there was no statistical pharmacokinetic difference for midazolam and omeprazole. Acute H2S poisoning could inhibit the activity of CYP2B6, CYP2D6, CYP1A2, and CYP2C9 in rats.

  12. Inhibition of cytochrome P450 enzymes by rhein in rat liver microsomes.

    Science.gov (United States)

    Tang, Jing-cheng; Yang, Hua; Song, Xue-ying; Song, Xiao-hong; Yan, Shu-lian; Shao, Jian-qun; Zhang, Tian-lan; Zhang, Jin-nan

    2009-02-01

    Rhein, an active ingredient extensively found in plants such as Aloe, Cassitora L., rhubarb and so on, has been used for a long time in China. Pharmacological tests revealed that rhein not only had a strong antibacterial action, but also may be useful in cancer chemotherapy as a biochemical modulator. Its therapeutic action and toxicity is still the subject of considerable research. With microsome incubation assays in vitro and HPLC methods, the inhibition of rat liver CYP1A2, CYP2C9, CYP2D6, CYP2E1 and CYP3A enzymes by rhein were studied kinetically. The results showed the most inhibition of CYP2E1 by rhein (K(i) = 10 microm, mixed); CYP3A and CYP2C9 were also inhibited by rhein, K(i) = 30 microm (mixed) and K(i) = 38 microm (mixed), respectively; rhein revealed some inhibition of CYP1A2 (K(i) = 62 microm, uncompetitive) and CYP2D6 (K(i) = 74 microm, mixed). Drug-drug interactions, especially cytochrome P450 (CYP)-mediated interactions, cause an enhancement or attenuation in the efficacy of co-administered drugs. Inhibition of the five major CYP enzymes observed for rhein suggested that changes in pharmacokinetics of co-administered drugs were likely to occur. Therefore, caution should be paid to the possible drug interaction of medicinal plants containing rhein and CYP substrates.

  13. Cytochrome P450 inhibition potential of new psychoactive substances of the tryptamine class.

    Science.gov (United States)

    Dinger, Julia; Woods, Campbell; Brandt, Simon D; Meyer, Markus R; Maurer, Hans H

    2016-01-22

    New psychoactive substances (NPS) are not tested for their cytochrome P450 (CYP) inhibition potential before consumption. Therefore, this potential was explored for tryptamine-derived NPS (TDNPS) including alpha-methyl tryptamines (AMTs), dimethyl tryptamines (DMTs), diallyl tryptamines (DALTs), and diisopropyl tryptamines (DiPTs) using test substrates preferred by the Food and Drug Administration in a cocktail assay. All tested TDNPS with the exception of DMT inhibited CYP2D6 activity with IC50 values below 100μM. DALTs inhibited CYP2D6 activity similar to paroxetine and quinidine and CYP1A2 activity comparable to fluvoxamine. 5-Methoxy-N,N-diallyltryptamine reduced in vivo the caffeine metabolism in rats consistent with in vitro results. Five of the AMTs also inhibited CYP1A2 activity comparable to amiodarone. AMT and 6-F-AMT inhibited CYP2A6 activity in the range of the test inhibitor tranylcypromine. CYP2B6 activity was inhibited by 19 tryptamines, but weakly compared to efavirenz. CYP2C8 activity was inhibited by five of the tested TDNPS and three showed values comparable to trimethoprim and gemfibrozil. Six tryptamines inhibited CYP2C9 and seven CYP2C19 activities comparable to fluconazole and chloramphenicol, respectively. Nineteen compounds showed inhibition of CYP2E1 and 18 of CYP3A activity, respectively. These results showed that the CYP inhibition by TDNPS might be clinically relevant, but clinical studies are needed to explore this further.

  14. The Effects of Acute Hydrogen Sulfide Poisoning on Cytochrome P450 Isoforms Activity in Rats

    Directory of Open Access Journals (Sweden)

    Xianqin Wang

    2014-01-01

    Full Text Available Hydrogen sulfide (H2S is the second leading cause of toxin related death (after carbon monoxide in the workplace. H2S is absorbed by the upper respiratory tract mucosa, and it causes histotoxic hypoxemia and respiratory depression. Cocktail method was used to evaluate the influences of acute H2S poisoning on the activities of cytochrome P450 isoforms CYP2B6, CYP2D6, CYP3A4, CYP1A2, CYP2C19, and CYP2C9, which were reflected by the changes of pharmacokinetic parameters of six specific probe drugs, bupropion, metoprolol, midazolam, phenacetin, omeprazole, and tolbutamide, respectively. The experimental rats were randomly divided into two groups, control group and acute H2S poisoning group (inhaling 300 ppm for 2 h. The mixture of six probes was given to rats by oral administration and the blood samples were obtained at a series of time points through the caudal vein. The concentrations of probe drugs in rat plasma were measured by LC-MS. The results for acute H2S poisoning and control groups were as follows: there was a statistically significant difference in the AUC and Cmax for bupropion, metoprolol, phenacetin, and tolbutamide, while there was no statistical pharmacokinetic difference for midazolam and omeprazole. Acute H2S poisoning could inhibit the activity of CYP2B6, CYP2D6, CYP1A2, and CYP2C9 in rats.

  15. Wpływ pojedynczej dawki paracetamolu i/lub N-acetylocysteiny na szczury przewlekle eksponowane na trichloroetylen. III. Wpływ na wybrane izoformy cytochromu P450 w wątrobie

    Directory of Open Access Journals (Sweden)

    Andrzej Plewka

    2012-12-01

    Full Text Available Background: In case of overdose of paracetamol the ability of hepatic biotransformation is saturated and accumulation of toxic metabolite – NAPQI takes place. Main CYP isoforms considered to be responsible for bioactivation of APAP and promoting the same liver intoxication are CYP2E1, CYP1A2, CYP3A4 and in animals 2B1/2 isoforms additionally. Purpose of this work was examination of paracetamol influence and/or trichloroethylene on the composition of hepatic cytochrome P450 isoforms. Materials and method: Tests were carried out on rats which were treated with trichloroethylene, paracetamol and/or N-acetylcysteine. In the microsomal fraction content of three isoforms of cytochrome P450 i.e. CYP2E1, CYP2B1/2 and CYP1A2 were determined. Results: Paracetamol slightly stimulated CYP2B1/2 lowering simultaneously level of CYP1A2. Trichloroethylene stimulated CYP2B1/2. N-acetylcysteine stimulated all tested P450 isoforms. N-acetylcysteine given together with examinated xenobiotics induced studied P450 isoforms. Conclusions: N-acetylcysteine demonstrated a protective effect on studied CYP isoforms especially when was given upon termination of xenobiotics exposure

  16. Light-driven cytochrome P450 hydroxylations

    DEFF Research Database (Denmark)

    Jensen, Kenneth; Jensen, Poul Erik; Møller, Birger Lindberg

    2011-01-01

    Plants are light-driven "green" factories able to synthesize more than 200,000 different bioactive natural products, many of which are high-value products used as drugs (e.g., artemisinin, taxol, and thapsigargin). In the formation of natural products, cytochrome P450 (P450) monooxygenases play...

  17. Dose-dependent inhibition of CYP1A2, CYP2C19 and CYP2D6 by citalopram, fluoxetine, fluvoxamine and paroxetine

    DEFF Research Database (Denmark)

    Jeppesen, U; Gram, L F; Vistisen, K

    1996-01-01

    OBJECTIVE: The purpose of this pharmacokinetic study was to investigate the dose-dependent inhibition of model substrates for CYP2D6, CYP2C19 and CYP1A2 by four marketed selective serotonin reuptake inhibitors (SSRIs): citalopram, fluoxetine, fluvoxamine and paroxetine. METHODS: The study...... by sparteine (CYP2D6), mephenytoin (CYP2C19) and caffeine (CYP1A2) tests. Fluoxetine was given at 3-week intervals because of the long half-life of fluoxetine and its metabolite norfluoxetine. Citalopram, fluoxetine and paroxetine were given in doses of 10, 20, 40 and 80 mg and fluvoxamine was given in doses...... after fluoxetine intake, although no volunteers changed phenotype from extensive metabolisers to poor metabolisers. Three of the six volunteers changed phenotype from extensive metabolisers to poor metabolisers after intake of 40 or 80 mg paroxetine. There was a statistically significant increase...

  18. The interindividual differences in the 3-demthylation of caffeine alias CYP1A2 is determined by both genetic and environmental factors

    DEFF Research Database (Denmark)

    Rasmussen, Birgitte B; Brix, Thomas H; Kyvik, Kirsten O

    2002-01-01

    This study investigated the role of genetic factors (CYP1A2) in caffeine metabolism. The CYP1A2 activity was determined in 378 Danish twins following oral intake of a single dose of 200 mg caffeine and subsequent determination of the caffeine ratio (AFMU+1MU+1MX)/17DMU in a 6-h urine sample....... The mean (+/- SD) caffeine ratio was 5.9 +/- 3.4. The caffeine ratio was statistically significantly higher in men compared to women, in smoking men and women compared to non-smoking persons of the same gender and in women not taking oral contraceptives compared with women on oral contraceptives. Thus, we....... A biometrical model for the caffeine ratio including only additive genetic factors and unique environmental factors was the overall best fitting model. Estimates based on this model gave a heritability estimate of 0.725 (95% confidence interval 0.577-0.822). Unique environmental effects seem to account...

  19. Coffee and tea consumption, genotype-based CYP1A2 and NAT2 activity and colorectal cancer risk-results from the EPIC cohort study.

    Science.gov (United States)

    Dik, Vincent K; Bueno-de-Mesquita, H B As; Van Oijen, Martijn G H; Siersema, Peter D; Uiterwaal, Cuno S P M; Van Gils, Carla H; Van Duijnhoven, Fränzel J B; Cauchi, Stéphane; Yengo, Loic; Froguel, Philippe; Overvad, Kim; Bech, Bodil H; Tjønneland, Anne; Olsen, Anja; Boutron-Ruault, Marie-Christine; Racine, Antoine; Fagherazzi, Guy; Kühn, Tilman; Campa, Daniele; Boeing, Heiner; Aleksandrova, Krasimira; Trichopoulou, Antonia; Peppa, Eleni; Oikonomou, Eleni; Palli, Domenico; Grioni, Sara; Vineis, Paolo; Tumino, Rosaria; Panico, Salvatore; Peeters, Petra H M; Weiderpass, Elisabete; Engeset, Dagrun; Braaten, Tonje; Dorronsoro, Miren; Chirlaque, María-Dolores; Sánchez, María-José; Barricarte, Aurelio; Zamora-Ros, Raul; Argüelles, Marcial; Jirström, Karin; Wallström, Peter; Nilsson, Lena M; Ljuslinder, Ingrid; Travis, Ruth C; Khaw, Kay-Tee; Wareham, Nick; Freisling, Heinz; Licaj, Idlir; Jenab, Mazda; Gunter, Marc J; Murphy, Neil; Romaguera-Bosch, Dora; Riboli, Elio

    2014-07-15

    Coffee and tea contain numerous antimutagenic and antioxidant components and high levels of caffeine that may protect against colorectal cancer (CRC). We investigated the association between coffee and tea consumption and CRC risk and studied potential effect modification by CYP1A2 and NAT2 genotypes, enzymes involved in the metabolization of caffeine. Data from 477,071 participants (70.2% female) of the European Investigation into Cancer and Nutrition (EPIC) cohort study were analyzed. At baseline (1992-2000) habitual (total, caffeinated and decaffeinated) coffee and tea consumption was assessed with dietary questionnaires. Cox proportional hazards models were used to estimate adjusted hazard ratio's (HR) and 95% confidence intervals (95% CI). Potential effect modification by genotype-based CYP1A2 and NAT2 activity was studied in a nested case-control set of 1,252 cases and 2,175 controls. After a median follow-up of 11.6 years, 4,234 participants developed CRC (mean age 64.7 ± 8.3 years). Total coffee consumption (high vs. non/low) was not associated with CRC risk (HR 1.06, 95% CI 0.95-1.18) or subsite cancers, and no significant associations were found for caffeinated (HR 1.10, 95% CI 0.97-1.26) and decaffeinated coffee (HR 0.96, 95% CI 0.84-1.11) and tea (HR 0.97, 95% CI 0.86-1.09). High coffee and tea consuming subjects with slow CYP1A2 or NAT2 activity had a similar CRC risk compared to non/low coffee and tea consuming subjects with a fast CYP1A2 or NAT2 activity, which suggests that caffeine metabolism does not affect the link between coffee and tea consumption and CRC risk. This study shows that coffee and tea consumption is not likely to be associated with overall CRC. © 2013 UICC.

  20. Analysis of nine drugs and their cytochrome P450-specific probe metabolites from urine by liquid chromatography-tandem mass spectrometry utilizing sub 2 microm particle size column.

    Science.gov (United States)

    Petsalo, Aleksanteri; Turpeinen, Miia; Pelkonen, Olavi; Tolonen, Ari

    2008-12-26

    An LC/MS/MS method was developed for the analysis of twelve cytochrome P450 (CYP)-specific probe metabolites and their nine parent drugs from human urine. CYP-specific metabolites of melatonin (CYP1A2), nicotine (CYP2A6), bupropion (CYP2B6), repaglinide (CYP2C8), losartan (CYP2C9), omeprazole (CYP2C19 and CYP3A4), dextromethorphan (CYP2D6), chlorzoxazone (CYP2E1) and midazolam (CYP3A4) were all analyzed using the same LC/MS/MS method with a single analytical run, either after a one-at-a-time dose or cocktail-type dosing of the parent drugs. Ultra performance liquid chromatography (UPLC) with a 1.7 microm particle size column was utilized, providing 1.5-3-fold increase in sensitivity, decrease of analysis time to one third and clearly better chromatographic peak shapes when comparing it with the method using traditional high performance liquid chromatography for the same metabolites. In addition, the method was applied for the analysis of the metabolites from human urine samples collected at multiple time points after single and N-in-one dosing of each of the drugs, showing that the use of both the analytical method and these probe metabolites as CYP-specific markers is feasible in in vivo drug-drug interaction or phenotyping studies.

  1. Lack of association between polymorphisms in the CYP1A2 gene and risk of cancer: evidence from meta-analyses.

    Science.gov (United States)

    Vukovic, Vladimir; Ianuale, Carolina; Leoncini, Emanuele; Pastorino, Roberta; Gualano, Maria Rosaria; Amore, Rosarita; Boccia, Stefania

    2016-02-10

    Polymorphisms in the CYP1A2 genes have the potential to affect the individual capacity to convert pre-carcinogens into carcinogens. With these comprehensive meta-analyses, we aimed to provide a quantitative assessment of the association between the published genetic association studies on CYP1A2 single nucleotide polymorphisms (SNPs) and the risk of cancer. We searched MEDLINE, ISI Web of Science and SCOPUS bibliographic online databases and databases of genome-wide association studies (GWAS). After data extraction, we calculated Odds Ratios (ORs) and 95% confidence intervals (CIs) for the association between the retrieved CYP1A2 SNPs and cancer. Random effect model was used to calculate the pooled ORs. Begg and Egger tests, one-way sensitivity analysis were performed, when appropriate. We conducted stratified analyses by study design, sample size, ethnicity and tumour site. Seventy case-control studies and one GWA study detailing on six different SNPs were included. Among the 71 included studies, 42 were population-based case-control studies, 28 hospital-based case-control studies and one genome-wide association study, including total of 47,413 cancer cases and 58,546 controls. The meta-analysis of 62 studies on rs762551, reported an OR of 1.03 (95% CI, 0.96-1.12) for overall cancer (P for heterogeneity < 0.01; I(2) = 50.4%). When stratifying for tumour site, an OR of 0.84 (95% CI, 0.70-1.01; P for heterogeneity = 0.23, I(2) = 28.5%) was reported for bladder cancer for those homozygous mutant of rs762551. An OR of 0.79 (95% CI, 0.65-0.95; P for heterogeneity = 0.09, I(2) = 58.1%) was obtained for the bladder cancer from the hospital-based studies and on Caucasians. This large meta-analysis suggests no significant effect of the investigated CYP1A2 SNPs on cancer overall risk under various genetic models. However, when stratifying according to the tumour site, our results showed a borderline not significant OR of 0.84 (95% CI, 0.70-1.01) for bladder cancer for those

  2. Benzydamine N-oxygenation as an index for flavin-containing monooxygenase activity and benzydamine N-demethylation by cytochrome P450 enzymes in liver microsomes from rats, dogs, monkeys, and humans.

    Science.gov (United States)

    Taniguchi-Takizawa, Tomomi; Shimizu, Makiko; Kume, Toshiyuki; Yamazaki, Hiroshi

    2015-02-01

    Benzydamine is an anti-inflammatory drug that undergoes flavin-containing monooxygenase (FMO)-dependent metabolism to benzydamine N-oxide; however, benzydamine N-demethylation is also catalyzed by liver microsomes. In this study, benzydamine N-oxygenation and N-demethylation mediated by liver microsomes from rats, dogs, monkeys, and humans were characterized comprehensively. Values of the maximum velocity/Michaelis constant ratio for benzydamine N-oxygenation by liver microsomes from dogs and rats were higher than those from monkeys and humans, despite roughly similar rates of N-demethylation in the four species. Benzydamine N-oxygenation by liver microsomes was extensively suppressed by preheating liver microsomes at 45 °C for 5 min or at 37 °C for 5-10 min without NADPH, and benzydamine N-demethylation was strongly inhibited by 1-aminbobenztriazole. Liver microsomal benzydamine N-oxygenation was inhibited by dimethyl sulfoxide and methimazole, whereas N-demethylation was inhibited by quinidine. High benzydamine N-oxygenation activities of recombinant human FMO1 and FMO3 and human kidney microsomes were observed at pH 8.4, whereas N-demethylation by cytochrome P450 2D6 was faster at pH 7.4. These results suggest that benzydamine N-oxygenation and N-demethylation are mediated by FMO1/3 and P450s, respectively, and that the contribution of FMO to metabolic eliminations of new drug candidates might be underestimated under certain experimental conditions suitable for P450 enzymes.

  3. Relevance of cytochrome P450s in plants: also one of Ron Estabrook's research interests.

    Science.gov (United States)

    Shet, Manjunath S

    2007-01-01

    I worked with Dr. Ronald Estabrook for nearly 10 years at The University of Texas Southwestern Medical Center in Dallas, Texas. In Ron's lab, when I joined I was initially involved in the isolation, purification, and characterization of cytochrome P450s and NADPH-P450(c) reductase(s) from plants, which was his new exploratory project at the time. We developed methods for the isolation, solubilization, and purification of P450s and NADPH-P450(c) reductase from plant tissue microsomes. We carried out number of in vitro experiments to study the involvement P450s and NADPH-P450(c) reductase in the biosynthesis of number of phytoalexins. We successfully isolated, purified, and cloned NADPH-P450(c) reductase from etiolated mung bean (Vigna radiate) seedlings. In addition, a series of studies were undertaken to show that purified mung bean NADPH-P450(c) reductase was able to catalyze P450-supported reactions for mammalian and bacterial P450s. My stay in Ron's lab was very educational and productive. He provided the necessary support and led the way through the maze in different research projects in the lab, which allowed me to understand the roles of P450s in humans, animals, plants, and microorganisms. He liked to teach and discover new things everyday in the lab. He is a great scientist, as well as loving and caring mentor.

  4. Cytochrome P450-mediated metabolic engineering

    DEFF Research Database (Denmark)

    Renault, Hugues; Bassard, Jean-Étienne André; Hamberger, Björn Robert

    2014-01-01

    for the engineered bioproduction of such compounds. Two ground-breaking developments of commercial products driven by the engineering of P450s are the antimalarial drug precursor artemisinic acid and blue roses or carnations. Tedious optimizations were required to generate marketable products. Hurdles encountered...... in P450 engineering and their potential solutions are summarized here. Together with recent technical developments and novel approaches to metabolic engineering, the lessons from this pioneering work should considerably boost exploitation of the amazing P450 toolkit emerging from accelerated sequencing...

  5. In vitro characterization of the cytochrome P450 isoforms involved in the metabolism of 6-methoxy-2-napthylacetic acid, an active metabolite of the prodrug nabumetone.

    Science.gov (United States)

    Matsumoto, Kaori; Nemoto, Eiichi; Hasegawa, Tetsuya; Akimoto, Masayuki; Sugibayashi, Kenji

    2011-01-01

    The cytochrome P450 (CYP) isoforms that catalyze the oxidation metabolism of 6-methoxy-2-napthylacetic acid (6-MNA), an active metabolite of nabumetone, were studied in rats and humans. Using an extractive reversed-phase HPLC assay with fluorescence detection, monophasic Michaelis-Menten kinetics was obtained for the formation of 6-hydroxy-2-naphthylacetic acid (6-HNA) in liver microsomes of rats and humans, and kinetic analysis showed that the K(m) and V(max) values for the formation of 6-HNA in humans and rats were 640.0 ± 30.9 and 722.9 ± 111.7 µM, and 1167.5 ± 33.0 and 1312.7 ± 73.8 pmol min⁻¹ mg protein⁻¹, respectively. The CYPs responsible for metabolism of 6-MNA in liver microsomes of rats and humans were identified using correlation study, recombinant CYP supersomes, and specific CYP inhibitors and antibodies. Recombinant human CYP2C9 exhibited appreciable catalytic activity with respect to 6-HNA formation from 6-MNA. Among 14 recombinant rat CYPs examined, CYP2C6, CYP2C11 and CYP1A2 were involved in the metabolism of 6-MNA. Sulfaphenazole (a selective inhibitor of CYP2C9) inhibited the formation of 6-HNA in pooled human microsomes by 89%, but failed to inhibit this reaction in rat liver microsomes. The treatment of pooled human liver microsomes with an antibody against CYP2C9 inhibited the formation of 6-HNA by about 80%. The antibody against CYP2C11 suppressed the activity by 20 to 30% in rat microsomes, whereas that of CYP1A2 microsomes did not show drastic inhibition. These findings suggest that CYP2C9 has the highest catalytic activity of 6-MNA metabolism in humans. In contrast, metabolism of 6-MNA is suggested to be mediated mainly by CYP2C6 and CYP2C11 in rats.

  6. Comparative study of the metabolism of drug substrates by human cytochrome P450 3A4 expressed in bacterial, yeast and human lymphoblastoid cells.

    Science.gov (United States)

    Andrews, J; Abd-Ellah, M F; Randolph, N L; Kenworthy, K E; Carlile, D J; Friedberg, T; Houston, J B

    2002-11-01

    1. The aim was to compare the metabolic activity of human CYP3A4 expressed in bacteria (E. coli), yeast (S. cerevisiae) and human lymphoblastoid cells (hBl), with the native CYP3A4 activity observed in a panel of human livers. 2. Three CYP3A4 substrates were selected for study: dextromethorphan (DEM), midazolam (MDZ) and diazepam (DZ). The substrate metabolism in each of the four systems was characterized by deriving the kinetic parameters K(m) or S(50), V(max) and intrinsic clearance (CL(int)) or maximum clearance (CL(max)) from the kinetic profiles; the latter differing by 100-fold across the three substrates. 3. The K(m) or S(50) for the formation of metabolites 3-methoxymorphinan (MEM), 1'-hydroxymidazolam (1'-OH MDZ) and 3-hydroxydiazepam (3HDZ) compared well in all systems. For CYP3A4-mediated metabolism of DEM, MDZ and DZ, the V(max) for hBl microsomes were generally 2-9-fold higher than the respective yeast and human liver microsomes and E. coli membrane preparations, resulting in greater CL(int) or CL(max). In the case of 3HDZ formation, non-linear kinetics were observed for E. coli, hBl microsomes and human liver microsomes, whereas the kinetics observed for S. cerevisiae were linear. 4. The use of native human liver microsomes for drug metabolic studies will always be preferable. However, owing to the limited availability of human tissues, we find it is reasonable to use any of the recombinant systems described herein, since all three recombinant systems gave good predictions of the native human liver enzyme activities.

  7. Oxidation of 1-chloropyrene by human CYP1 family and CYP2A subfamily cytochrome P450 enzymes: catalytic roles of two CYP1B1 and five CYP2A13 allelic variants.

    Science.gov (United States)

    Shimada, Tsutomu; Murayama, Norie; Kakimoto, Kensaku; Takenaka, Shigeo; Lim, Young-Ran; Yeom, Sora; Kim, Donghak; Yamazaki, Hiroshi; Guengerich, F Peter; Komori, Masayuki

    2017-07-21

    1. 1-Chloropyrene, one of the major chlorinated polycyclic aromatic hydrocarbon contaminants, was incubated with human cytochrome P450 (P450 or CYP) enzymes including CYP1A1, 1A2, 1B1, 2A6, 2A13, 2B6, 2C9, 2D6, 2E1, 3A4 and 3A5. Catalytic differences in 1-chloropyrene oxidation by polymorphic two CYP1B1 and five CYP2A13 allelic variants were also examined. 2. CYP1A1 oxidized 1-chloropyrene at the 6- and 8-positions more actively than at the 3-position, while both CYP1B1.1 and 1B1.3 preferentially catalyzed 6-hydroxylation. 3. Five CYP2A13 allelic variants oxidized 8-hydroxylation much more than 6- and 3-hydroxylation, and the variant CYP2A13.3 was found to slowly catalyze these reactions with a lower kcat value than other CYP2A13.1 variants. 4. CYP2A6 catalyzed 1-chloropyrene 6-hydroxylation at a higher rate than the CYP2A13 enzymes, but the rate was lower than the CYP1A1 and 1B1 variants. Other human P450 enzymes had low activities towards 1-chloropyrene. 5. Molecular docking analysis suggested differences in the interaction of 1-chloropyrene with active sites of CYP1 and 2 A enzymes. In addition, a naturally occurring Thr134 insertion in CYP2A13.3 was found to affect the orientation of Asn297 in the I-helix in interacting with 1-chloropyrene (and also 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone, NNK) and caused changes in the active site of CYP2A13.3 as compared with CYP2A13.1.

  8. Validation of cytochrome P450 time-dependent inhibition assays: a two-time point IC50 shift approach facilitates kinact assay design.

    Science.gov (United States)

    Perloff, E S; Mason, A K; Dehal, S S; Blanchard, A P; Morgan, L; Ho, T; Dandeneau, A; Crocker, R M; Chandler, C M; Boily, N; Crespi, C L; Stresser, D M

    2009-02-01

    1. Recent guidance from the US Food and Drug Administration (USFDA) has advocated testing of time-dependent inhibition of cytochrome P450 (CYP), which can be addressed by performing IC(50) shift as well as K(I)/k(inact) determinations. 2. Direct (IC(50), K(i)) and time-dependent inhibition (IC(50) shift, K(I)/k(inact)) assays were validated in human liver microsomes with liquid chromatography-tandem mass spectrometry (LC/MS/MS) analysis for the following enzyme/substrate/inhibitor combinations: CYP1A2/phenacetin/alpha-naphthoflavone/furafylline, CYP2C8/amodiaquine/montelukast/gemfibrozil-1-O-beta-glucuronide, CYP2C9/diclofenac/sulfaphenazole/tienilic acid, CYP2C19/S-mephenytoin/S-benzylnirvanol/S-fluoxetine, CYP2D6/dextromethorphan/quinidine/paroxetine, and CYP3A4/midazolam/testosterone/ketoconazole/azamulin/verapamil/diltiazem. IC(50) shift assays were performed with two pre-incubation time points (10 and 30 min) to facilitate k(inact) assay design. 3. Data obtained show good agreement with literature values. For rapid acting inhibitors, such as azamulin/CYP3A4 and tienilic acid/CYP2C9, the IC(50) shifts were similar at both time points suggesting a short maximum pre-incubation time with closely spaced time points for the K(I)/k(inact) assay. Slow acting inhibitors (such as verapamil/CYP3A4 or S-fluoxetine/CYP2C19) showed an increase in IC(50) shift between 10 and 30 min suggesting a longer maximum pre-incubation time with wider spacing of time points for K(I)/k(inact). 4. The two-time point IC(50) shift experiment proved to be an excellent method for the selection of appropriate K(I)/k(inact) assay parameters and is suitable for the routine analysis of P450 inhibition by drug candidates.

  9. Cytochromes P450 and insecticide resistance.

    Science.gov (United States)

    Scott, J G

    1999-09-01

    The cytochrome P450-dependent monooxygenases (monooxygenases) are an extremely important metabolic system involved in the catabolism and anabolism of xenobiotics and endogenous compounds. Monooxygenase-mediated metabolism is a common mechanism by which insects become resistant to insecticides as evidenced by the numerous insect species and insecticides affected. This review begins by presenting background information about P450s, the role of monooxygenases in insects, and the different techniques that have been used to isolate individual insect P450s. Next, insecticide resistance is briefly described, and then historical information about monooxygenase-mediated insecticide resistance is reviewed. For any case of monooxygenase-mediated resistance, identification of the P450(s) involved, out of the dozens that are present in an insect, has proven very challenging. Therefore, the next section of the review focuses on the minimal criteria for establishing that a P450 is involved in resistance. This is followed by a comprehensive examination of the literature concerning the individual P450s that have been isolated from insecticide resistant strains. In each case, the history of the strain and the evidence for monooxygenase-mediated resistance are reviewed. The isolation and characterization of the P450(s) from the strain are then described, and the evidence of whether or not the isolated P450(s) is involved in resistance is summarized. The remainder of the review summarizes our current knowledge of the molecular basis of monooxygenase-mediated resistance and the implications for the future. The importance of these studies for development of effective insecticide resistance management strategies is discussed.

  10. Three new alternative splicing variants of human cytochrome P450 2D6 mRNA in human extratumoral liver tissue

    Institute of Scientific and Technical Information of China (English)

    Jian Zhuge; Ying-Nian Yu

    2004-01-01

    AIM: To identify the new alternative splicing variants of human CYP2D6 in human extratumoral liver tissue with RT-PCR and sequencing.METHODS: Full length of human CYP2D6 cDNAs was amplificated by reverse transcription-polymerase chain reaction (RT-PCR) from a human extratumoral liver tissue and cloned into pGEM-T vector. The cDNA was sequenced.Exons from 1 to 4 of human CYP2D6 cDNAs were also amplificated by RT-PCR from extratumoral liver tissues of17 human hepatocellular carcinomas. Some RT-PCR products were sequenced. Exons 1 to 4 of CYP2D6 gene were amplified by PCR from extratumoral liver tissue DNA.Two PCR products from extratumoral liver tissues expressing skipped mRNA were partially sequenced.RESULTS: One of the CYP2D6cDNAs had 470 nucleotides from 79 to 548 (3' portion of exons 1 to 5' portion of exon 4),and was skipped. Exons 1 to 4 of CYP2D6 cDNA were assayed with RT-PCR in 17 extratumoral liver tissues. Both wild type and skipped mRNAs were expressed in 4 samples,only wild type mRNA was expressed in 5 samples, and only skipped mRNA was expressed in 8 samples. Two more variants were identified by sequencing the RT-PCR products of exons 1 to 4 of CYP2D6cDNA. The second variant skipped 411 nucleotides from 175 to 585. This variant was identified in 4 different liver tissues by sequencing the RT-PCR products. We sequenced partially 2 of the PCR products amplified of CYP2D6 exon 1 to exon 4 from extratumoral liver tissue genomic DNA that only expressed skipped mRNA by RT-PCR. No point mutations around exon 1, intron 1, and exon 4, and no deletion in CYP2D6gene were detected. The third variant was the skipped exon 3, and 153 bp was lost.CONCLUSION: Three new alternative splicing variants of CYP2D6 mRNA have been identified. They may not be caused by gene mutation and may lose CYP2D6 activity and act as a down-regulator of CYP2D6.

  11. 20-Hydroxycholecalciferol, product of vitamin D3 hydroxylation by P450scc, decreases NF-kappaB activity by increasing IkappaB alpha levels in human keratinocytes.

    Directory of Open Access Journals (Sweden)

    Zorica Janjetovic

    Full Text Available The side chain of vitamin D3 is hydroxylated in a sequential manner by cytochrome P450scc (CYP11A1 to form 20-hydroxycholecalciferol, which can induce growth arrest and differentiation of both primary and immortalized epidermal keratinocytes. Since nuclear factor-kappaB (NF-kappaB plays a pivotal role in the regulation of cell proliferation, differentiation and apoptosis, we examined the capability of 20-hydroxycholecalciferol to modulate the activity of NF-kappaB, using 1,25-dihydroxycholecalciferol (calcitriol as a positive control. 20-hydroxycholecalciferol inhibits the activation of NFkappaB DNA binding activity as well as NF-kappaB-driven reporter gene activity in keratinocytes. Also, 20-hydroxycholecalciferol induced significant increases in the mRNA and protein levels of the NF-kappaB inhibitor protein, IkappaB alpha, in a time dependent manner, while no changes in total NF-kappaB-p65 mRNA or protein levels were observed. Another measure of NF-kappaB activity, p65 translocation from the cytoplasm into the nucleus was also inhibited in extracts of 20-hydroxycholecalciferol treated keratinocytes. Increased IkappaB alpha was concomitantly observed in cytosolic extracts of 20-hydroxycholecalciferol treated keratinocytes, as determined by immunoblotting and immunofluorescent staining. In keratinocytes lacking vitamin D receptor (VDR, 20-hydroxycholecalciferol did not affect IkappaB alpha mRNA levels, indicating that it requires VDR for its action on NF-kappaB activity. Comparison of the effects of calcitrol, hormonally active form of vitamin D3, with 20-hydrocholecalciferol show that both agents have a similar potency in inhibiting NF-kappaB. Since NF-kappaB is a major transcription factor for the induction of inflammatory mediators, our findings indicate that 20-hydroxycholecalciferol may be an effective therapeutic agent for inflammatory and hyperproliferative skin diseases.

  12. Modulation of CYP1A1 and CYP1A2 hepatic enzymes after oral administration of Chios mastic gum to male Wistar rats.

    Science.gov (United States)

    Katsanou, Efrosini S; Kyriakopoulou, Katerina; Emmanouil, Christina; Fokialakis, Nikolas; Skaltsounis, Alexios-Leandros; Machera, Kyriaki

    2014-01-01

    Chios mastic gum (CMG), a resin derived from Pistacia lentiscus var. chia, is known since ancient times for its pharmacological activities. CYP1A1 and CYP1A2 enzymes are among the most involved in the biotransformation of chemicals and the metabolic activation of pro-carcinogens. Previous studies referring to the modulation of these enzymes by CMG have revealed findings of unclear biological and toxicological significance. For this purpose, the modulation of CYP1A1 and CYP1A2 enzymes in the liver of male Wistar rats following oral administration of CMG extract (CMGE), at the levels of mRNA and CYP1A1 enzyme activity, was compared to respective enzyme modulation following oral administration of a well-known bioactive natural product, caffeine, as control compound known to involve hepatic enzymes in its metabolism. mRNA levels of Cyp1a1 and Cyp1a2 were measured by reverse transcription real-time polymerase chain reaction and their relative quantification was calculated. CYP1A1 enzyme induction was measured through the activity of ethoxyresorufin-O-deethylase (EROD). The results indicated that administration of CMGE at the recommended pharmaceutical dose does not induce significant transcriptional modulation of Cyp1a1/2 and subsequent enzyme activity induction of CYP1A1 while effects of the same order of magnitude were observed in the same test system following the administration of caffeine at the mean daily consumed levels. The outcome of this study further confirms the lack of any toxicological or biological significance of the specific findings on liver following the administration of CMGE.

  13. Modulation of CYP1A1 and CYP1A2 hepatic enzymes after oral administration of Chios mastic gum to male Wistar rats.

    Directory of Open Access Journals (Sweden)

    Efrosini S Katsanou

    Full Text Available Chios mastic gum (CMG, a resin derived from Pistacia lentiscus var. chia, is known since ancient times for its pharmacological activities. CYP1A1 and CYP1A2 enzymes are among the most involved in the biotransformation of chemicals and the metabolic activation of pro-carcinogens. Previous studies referring to the modulation of these enzymes by CMG have revealed findings of unclear biological and toxicological significance. For this purpose, the modulation of CYP1A1 and CYP1A2 enzymes in the liver of male Wistar rats following oral administration of CMG extract (CMGE, at the levels of mRNA and CYP1A1 enzyme activity, was compared to respective enzyme modulation following oral administration of a well-known bioactive natural product, caffeine, as control compound known to involve hepatic enzymes in its metabolism. mRNA levels of Cyp1a1 and Cyp1a2 were measured by reverse transcription real-time polymerase chain reaction and their relative quantification was calculated. CYP1A1 enzyme induction was measured through the activity of ethoxyresorufin-O-deethylase (EROD. The results indicated that administration of CMGE at the recommended pharmaceutical dose does not induce significant transcriptional modulation of Cyp1a1/2 and subsequent enzyme activity induction of CYP1A1 while effects of the same order of magnitude were observed in the same test system following the administration of caffeine at the mean daily consumed levels. The outcome of this study further confirms the lack of any toxicological or biological significance of the specific findings on liver following the administration of CMGE.

  14. Cytochrome P450 1B1, a new keystone in gene-environment interactions related to human head and neck cancer?

    Energy Technology Data Exchange (ETDEWEB)

    Thier, R. [Dept. Physiology and Pharmacology, Univ. of Queensland, St. Lucia, Qld. (Australia); Bruening, T. [Berufsgenossenschaftliches Forschungsinstitut fuer Arbeitsmedizin (BGFA), Bochum (Germany); Roos, P.H.; Bolt, H.M. [Inst. fuer Arbeitsphysiologie an der Univ. Dortmund (IfADo), Dortmund (Germany)

    2002-06-01

    Alcohol consumption and tobacco smoking are major causes of head and neck cancers, and regional differences point to the importance of research into gene-environment interactions. Much interest has been focused on polymorphisms of CYP1A1 and of GSTM1 and GSTT1, but a number of studies have not demonstrated significant effects. This has mostly been ascribed to small sample sizes. In general, the impact of polymorphisms of metabolic enzymes appears inconsistent, with some reports of weak-to-moderate associations, and with other of no elevation of risks. The classical cytochrome P450 isoenzyme considered for metabolic activation of polycyclic aromatic hydrocarbons (PAH) is CYP1A1. A new member of CYP1 family, CYP1B1, was cloned in 1994, currently representing the only member of the CYP1B subfamily. A number of single nucleotide polymorphisms of the CYP1B1 gene have been reported. The amino acid substitutions Val432Leu (CYP1B1*3) and Asn453Ser (CYP1B1*4), located in the heme binding domain of CYP1B1, appear as likely candidates to be linked with biological effects. CYP1B1 activates a wide range of PAH, aromatic and heterocyclic amines. Very recently, the CYP1B1 codon 432 polymorphism (CYP1B1*3) has been identified as a susceptibility factor in smoking-related head-and-neck squamous cell cancer. The impact of this polymorphic variant of CYP1B1 on cancer risk was also reflected by an association with the frequency of somatic mutations of the p53 gene. Combined genotype analysis of CYP1B1 and the glutathione transferases GSTM1 or GSTT1 has pointed to interactive effects. This provides new molecular evidence that tobacco smoke-specific compounds relevant to head and neck carcinogenesis are metabolically activated through CYP1B1 and is consistent with a major pathogenetic relevance of PAH as ingredients of tobacco smoke. (orig.)

  15. Virtual Screening and Prediction of Site of Metabolism for Cytochrome P450 1A2 Ligands

    DEFF Research Database (Denmark)

    Vasanthanathan, P.; Hritz, Jozef; Taboureau, Olivier

    2009-01-01

    With the availability of an increasing number of high resolution 3D structures of human cytochrome P450 enzymes, structure-based modeling tools are more readily used. In this study we explore the possibilities of using docking and scoring experiments on cytochrome P450 1A2. Three different...... and earlier classification data using machine learning methods. The possibilities and limitations of using structure-based drug design tools for cytochrome P450 1A2 come to light and are discussed....

  16. Roles of Human CYP2A6 and Monkey CYP2A24 and 2A26 Cytochrome P450 Enzymes in the Oxidation of 2,5,2',5'-Tetrachlorobiphenyl.

    Science.gov (United States)

    Shimada, Tsutomu; Kakimoto, Kensaku; Takenaka, Shigeo; Koga, Nobuyuki; Uehara, Shotaro; Murayama, Norie; Yamazaki, Hiroshi; Kim, Donghak; Guengerich, F Peter; Komori, Masayuki

    2016-12-01

    2,5,2',5'-Tetrachlorobiphenyl (TCB) induced type I binding spectra with cytochrome P450 (P450) 2A6 and 2A13, with Ks values of 9.4 and 0.51 µM, respectively. However, CYP2A6 oxidized 2,5,2',5'-TCB to form 4-hydroxylated products at a much higher rate (∼1.0 minute(-1)) than CYP2A13 (∼0.02 minute(-1)) based on analysis by liquid chromatography-tandem mass spectrometry. Formation of 4-hydroxy-2,5,2',5'-TCB by CYP2A6 was greater than that of 3-hydroxy-2,5,2',5'-TCB and three other hydroxylated products. Several human P450 enzymes, including CYP1A1, 1A2, 1B1, 2B6, 2D6, 2E1, 2C9, and 3A4, did not show any detectable activities in oxidizing 2,5,2',5'-TCB. Cynomolgus monkey CYP2A24, which shows 95% amino acid identity to human CYP2A6, catalyzed 4-hydroxylation of 2,5,2',5'-TCB at a higher rate (∼0.3 minute(-1)) than CYP2A26 (93% identity to CYP2A6, ∼0.13 minute(-1)) and CYP2A23 (94% identity to CYP2A13, ∼0.008 minute(-1)). None of these human and monkey CYP2A enzymes were catalytically active in oxidizing other TCB congeners, such as 2,4,3',4'-, 3,4,3',4'-, and 3,5,3',5'-TCB. Molecular docking analysis suggested that there are different orientations of interaction of 2,5,2',5'-TCB with the active sites (over the heme) of human and monkey CYP2A enzymes, and that ligand interaction energies (U values) of bound protein-ligand complexes show structural relationships of interaction of TCBs and other ligands with active sites of CYP2A enzymes. Catalytic differences in human and monkey CYP2A enzymes in the oxidation of 2,5,2',5'-TCB are suggested to be due to amino acid changes at substrate recognition sites, i.e., V110L, I209S, I300F, V365M, S369G, and R372H, based on the comparison of primary sequences. Copyright © 2016 by The American Society for Pharmacology and Experimental Therapeutics.

  17. Ruthenium-containing P450 inhibitors for dual enzyme inhibition and DNA damage.

    Science.gov (United States)

    Zamora, Ana; Denning, Catherine A; Heidary, David K; Wachter, Erin; Nease, Leona A; Ruiz, José; Glazer, Edith C

    2017-02-14

    Cytochrome P450s are key players in drug metabolism, and overexpression in tumors is associated with significant resistance to many medicinal agents. Consequently, inhibition of P450s could serve as a strategy to restore drug efficacy. However, the widespread expression of P450s throughout the human body and the critical roles they play in various biosynthetic pathways motivates the development of P450 inhibitors capable of controlled local administration. Ruthenium complexes containing P450 inhibitors as ligands were synthesized in order to develop pro-drugs that can be triggered to release the inhibitors in a spatially and temporally controlled fashion. Upon light activation the compounds release ligands that directly bind and inhibit P450 enzymes, while the ruthenium center is able to directly damage DNA.

  18. Flower colour and cytochromes P450

    OpenAIRE

    Tanaka, Yoshikazu; Brugliera, Filippa

    2013-01-01

    Cytochromes P450 play important roles in biosynthesis of flavonoids and their coloured class of compounds, anthocyanins, both of which are major floral pigments. The number of hydroxyl groups on the B-ring of anthocyanidins (the chromophores and precursors of anthocyanins) impact the anthocyanin colour, the more the bluer. The hydroxylation pattern is determined by two cytochromes P450, flavonoid 3′-hydroxylase (F3′H) and flavonoid 3′,5′-hydroxylase (F3′5′H) and thus they play a crucial role ...

  19. Nerval influences on liver cytochrome P450.

    Science.gov (United States)

    Klinger, W; Karge, E; Danz, M; Krug, M

    1995-09-01

    In male young adult Wistar rats the influences of nucleus raphe electrocoagulation, spinal cord dissection (cordotomy between C7 and Th1), vagotomy and denervation of liver hilus by phenol on liver cytochrome P450-system (cytochrome P450 concentration, ethylmorphine N-demethylation and ethoxycoumarin O-deethylation activities, hexobarbitone sleeping time) were investigated. In general the influences were small or negligible when compared with sham operated controls, only after vagotomy the depressing effect of sham operation was abolished. In all cases sham operation had a depressing effect until up to five weeks after operation.

  20. Albendazole metabolism in patients with neurocysticercosis: antipyrine as a multifunctional marker drug of cytochrome P450

    Directory of Open Access Journals (Sweden)

    M.P. Marques

    2002-02-01

    Full Text Available The present study investigates the isoform(s of cytochrome P450 (CYP involved in the metabolism of albendazole sulfoxide (ASOX to albendazole sulfone (ASON in patients with neurocysticercosis using antipyrine as a multifunctional marker drug. The study was conducted on 11 patients with neurocysticercosis treated with a multiple dose regimen of albendazole for 8 days (5 mg/kg every 8 h. On the 5th day of albendazole treatment, 500 mg antipyrine was administered po. Blood and urine samples were collected up to 72 h after antipyrine administration. Plasma concentrations of (+-ASOX, (--ASOX and ASON were determined by HPLC using a chiral phase column and detection by fluorescence. The apparent clearance (CL/f of ASON and of the (+ and (--ASOX enantiomers were calculated and compared to total antipyrine clearance (CL T and the clearance for the production of the three major antipyrine metabolites (CLm. A correlation (P<=0.05 was obtained only between the CL T of antipyrine and the CL/f of ASON (r = 0.67. The existence of a correlation suggests the involvement of CYP isoforms common to the metabolism of antipyrine and of ASOX to ASON. Since the CL T of antipyrine is a general measure of CYP enzymes but with a slight to moderate weight toward CYP1A2, we suggest the involvement of this enzyme in ASOX to ASON metabolism in man. The study supports the establishment of a specific marker drug of CYP1A2 in the study of the in vivo metabolism of ASOX to ASON.

  1. Differential Expression of Cytochrome P450 Enzymes in Normal and Tumor Tissues from Childhood Rhabdomyosarcoma

    Science.gov (United States)

    Molina-Ortiz, Dora; Camacho-Carranza, Rafael; González-Zamora, José Francisco; Shalkow-Kalincovstein, Jaime; Cárdenas-Cardós, Rocío; Ností-Palacios, Rosario; Vences-Mejía, Araceli

    2014-01-01

    Intratumoral expression of genes encoding Cytochrome P450 enzymes (CYP) might play a critical role not only in cancer development but also in the metabolism of anticancer drugs. The purpose of this study was to compare the mRNA expression patterns of seven representative CYPs in paired tumor and normal tissue of child patients with rabdomyosarcoma (RMS). Using real time quantitative RT-PCR, the gene expression pattern of CYP1A1, CYP1A2, CYP1B1, CYP2E1, CYP2W1, CYP3A4, and CYP3A5 were analyzed in tumor and adjacent non-tumor tissues from 13 child RMS patients. Protein concentration of CYPs was determined using Western blot. The expression levels were tested for correlation with the clinical and pathological data of the patients. Our data showed that the expression levels of CYP1A1 and CYP1A2 were negligible. Elevated expression of CYP1B1 mRNA and protein was detected in most RMS tumors and adjacent normal tissues. Most cancerous samples exhibit higher levels of both CYP3A4 and CYP3A5 compared with normal tissue samples. Expression of CYP2E1 mRNA was found to be significantly higher in tumor tissue, however no relation was found with protein levels. CYP2W1 mRNA and/or protein are mainly expressed in tumors. In conclusion, we defined the CYP gene expression profile in tumor and paired normal tissue of child patients with RMS. The overexpression of CYP2W1, CYP3A4 and CYP3A5 in tumor tissues suggests that they may be involved in RMS chemoresistance; furthermore, they may be exploited for the localized activation of anticancer prodrugs. PMID:24699256

  2. Effects of Polygonum multiflorum on the activity of cytochrome P450 isoforms in rats.

    Science.gov (United States)

    Zhang, Yuan; Ding, Ting; Diao, Tingting; Deng, Mengjiao; Chen, Suhong

    2015-01-01

    Polygonum multiflorum is a traditional Chinese medicinal herb used in clinical medicine to nourish the liver and kidney. However, in recent years, there have been increased reports of clinical adverse reactions associated with Polygonum multiflorum preparations, especially due to liver injury. The cocktail method can be used to assess the influence of Polygonum multiflorum on the activity of cytochrome P450 (CYP450) isoforms CYP2B6, CYP2C19, CYP2C9, CYP1A2, CYP3A4, and CYP2D6, which were reflected by changes in pharmacokinetic parameters in six specific probe drugs: bupropion, omeprazole, tolbutamide, phenacetin, midazolam, and metoprolol. Comprised the experimental rats were randomly divided into five groups: control group, alcohol extraction A group, alcohol extraction B group, water extraction A group, and water extraction B group. Each group five male rats and five female rats. Each of the groups received treatments by gavage as follows: control group was given normal saline, alcohol extraction A group was given 15 g/kg alcohol extract of Polygonum multiflorum (E15), alcohol extraction B group was given with 30 g/kg alcohol extract (E30), water extraction A group was given 15 g/kg water extract (W15), and water extraction B group was given 30 g/kg water extract (W30). The extract solution was orally administered once a day for 28 consecutive days. The mixture of six probe drugs was given by gavage, and blood samples were collected through the tail vein at different time points. Probe drug concentration in rat plasma was measured by liquid chromatography-mass spectrometry (LC-MS). In the treatment and control groups, Polygonum multiflorum alcoholic extract inhibited the activity of CYP2C19 and CYP2C9 and induced the activity of CYP1A2. Polygonum multiflorum aquous extract inhibited the activity of CYP2B6, CYP2C19, CYP2C9, CYP1A2, and CYP2D6. Pathological sections showed that in the alcohol extract group the liver was degenerated inconspicuously, and in the water

  3. Prediction of cytochrome P450 mediated metabolism

    DEFF Research Database (Denmark)

    Olsen, Lars; Oostenbrink, Chris; Jørgensen, Flemming Steen

    2015-01-01

    Cytochrome P450 enzymes (CYPs) form one of the most important enzyme families involved in the metabolism of xenobiotics. CYPs comprise many isoforms, which catalyze a wide variety of reactions, and potentially, a large number of different metabolites can be formed. However, it is often hard...

  4. Intronic polymorphisms of cytochromes P450

    Directory of Open Access Journals (Sweden)

    Ingelman-Sundberg Magnus

    2010-08-01

    Full Text Available Abstract The cytochrome P450 enzymes active in drug metabolism are highly polymorphic. Most allelic variants have been described for enzymes encoded by the cytochrome P450 family 2 (CYP2 gene family, which has 252 different alleles. The intronic polymorphisms in the cytochrome P450 genes account for only a small number of the important variant alleles; however, the most important ones are CYP2D6*4 and CYP2D6*41, which cause abolished and reduced CYP2D6 activity, respectively, and CYP3A5*3 and CYP3A5*5, common in Caucasian populations, which cause almost null activity. Their discoveries have been based on phenotypic alterations within individuals in a population, and their identification has, in several cases, been difficult and taken a long time. In light of the next-generation sequencing projects, it is anticipated that further alleles with intronic mutations will be identified that can explain the hitherto unidentified genetic basis of inter-individual differences in cytochrome P450-mediated drug and steroid metabolism.

  5. Resveratrol stimulates cortisol biosynthesis by activating SIRT-dependent deacetylation of P450scc.

    Science.gov (United States)

    Li, Donghui; Dammer, Eric B; Sewer, Marion B

    2012-07-01

    In the human adrenal cortex, cortisol is synthesized from cholesterol by members of the cytochrome P450 superfamily and hydroxysteroid dehydrogenases. Both the first and last steps of cortisol biosynthesis occur in mitochondria. Based on our previous findings that activation of ACTH signaling changes the ratio of nicotinamide adenine dinucleotide (NAD) phosphate to reduced NAD phosphate in adrenocortical cells, we hypothesized that pyridine nucleotide metabolism may regulate the activity of the mitochondrial NAD(+)-dependent sirtuin (SIRT) deacetylases. We show that resveratrol increases the protein expression and half-life of P450 side chain cleavage enzyme (P450scc). The effects of resveratrol on P450scc protein levels and acetylation status are dependent on SIRT3 and SIRT5 expression. Stable overexpression of SIRT3 abrogates the cellular content of acetylated P450scc, concomitant with an increase in P450scc protein expression and cortisol secretion. Mutation of K148 and K149 to alanine stabilizes the expression of P450scc and results in a 1.5-fold increase in pregnenolone biosynthesis. Finally, resveratrol also increases the protein expression of P450 11β, another mitochondrial enzyme required for cortisol biosynthesis. Collectively, this study identifies a role for NAD(+)-dependent SIRT deacetylase activity in regulating the expression of mitochondrial steroidogenic P450.

  6. Metabolism of methyl tert-butyl ether and other gasoline ethers by human liver microsomes and heterologously expressed human cytochromes P450: identification of CYP2A6 as a major catalyst.

    Science.gov (United States)

    Hong, J Y; Wang, Y Y; Bondoc, F Y; Lee, M; Yang, C S; Hu, W Y; Pan, J

    1999-10-01

    To reduce the production of carbon monoxide and other pollutants in motor vehicle exhaust, methyl tert-butyl ether (MTBE), ethyl tert-butyl ether (ETBE), and tert-amyl methyl ether (TAME) are added to gasoline as oxygenates for more complete combustion. Previously, we demonstrated that human liver is active in metabolizing MTBE to tert-butyl alcohol (TBA) and that cytochrome P450 (CYP) enzymes play a critical role in the metabolism of MTBE. The present study demonstrates that human liver is also active in the oxidative metabolism of ETBE and TAME. A large interindividual variation in metabolizing these gasoline ethers was observed in 15 human liver microsomal samples. The microsomal activities in metabolizing MTBE, ETBE, and TAME were highly correlated among each other (r, 0.91-0. 96), suggesting that these ethers are metabolized by the same enzyme(s). Correlation analysis of the ether-metabolizing activities with individual CYP enzyme activities in the liver microsomes showed that the highest degree of correlation was with human CYP2A6 (r, 0. 90-0.95), which is constitutively expressed in human livers and known to be polymorphic. CYP2A6 displayed the highest turnover number in metabolizing gasoline ethers among a battery of human CYP enzymes expressed in human B-lymphoblastoid cells. Kinetic studies on MTBE metabolism with three human liver microsomes exhibited apparent Km values that ranged from 28 to 89 microM and the V(max) values from 215 to 783 pmol/min/mg, with similar catalytic efficiency values (7.7 to 8.8 microl/min/mg protein). Metabolism of MTBE, ETBE, and TAME by human liver microsomes was inhibited by coumarin, a known substrate of human CYP2A6, in a concentration-dependent manner. Monoclonal antibody against human CYP2A6 caused a significant inhibition (75% to 95%) of the metabolism of MTBE, ETBE, and TAME in human liver microsomes. Taken together, these results clearly indicate that in human liver, CYP2A6 is the major enzyme responsible for the

  7. Theoretical study of the cytochrome P450 mediated metabolism of phosphorodithioate pesticides

    DEFF Research Database (Denmark)

    Rydberg, Patrik

    2012-01-01

    The toxicity of phosphorodithioate pesticides is due to the formation of the active oxane product through desulfurization by cytochrome P450 enzymes, both in humans and insects. During this desulfurization, inhibition of cytochrome P450 and a loss of heme has been observed. Here, we study...

  8. Cocktail法评价注射用丹参总酚酸对大鼠肝微粒体CYP1A2和CYP3A的诱导作用%Effect of total salvianolic acid injection on the activity of hepatic CYP1A2 and CYP3A in rats by Cocktail method

    Institute of Scientific and Technical Information of China (English)

    胡冰; 段超慧; 岳洁皓; 叶正良; 周大铮; 李德坤; 马英丽

    2012-01-01

    目的:考察注射用丹参总酚酸(TSAI)对大鼠肝微粒体CYP1A2和CYP3A的诱导作用.方法:健康Wistar大鼠随机分为空白对照组、苯巴比妥钠诱导组和给药组,每组6只,雌雄各半,连续给药7d,处死,制备肝微粒体;将特异性探针底物非那西丁、睾酮与肝微粒体共孵育,高效液相色谱测定孵育所得代谢产物对乙酰氨基酚和6β-羟基睾酮的生成速率,评价TSAI对CYP1A2和CYP3A的诱导作用.结果:空白对照组、诱导组和给药组的对乙酰氨基酚的生成速率分别为(18.04±1.00),(43.07±2.90)和(16.03±2.41)ng· mg ·min-,6β-羟基睾酮的生成速率分别为(15.79±1.43),(40.86±3.32)和(17.12±2.65) ng·mg-1·min-1.结论:TSAI对大鼠肝微粒体CYP1A2和CYP3A无诱导作用.%Objective: To investigate the inducing effect of total salvianolic acid injection (TSAI) on CYP1A2 and CYP3A in rat liver microsomes. Methods: Healthy Wistar rats were randomly divided into 3 groups (n =6, 3 males and 3 females) ; blank control, phenobarbital-treated and TSAI groups. The rats were sacrificed 7 days after administration and liver microsomes were prepared. Rat liver microsomes were incubated with the cocktail selective substrates consisting of the phenacetin (PN, CYP1A2) and testosterone (TS, CYP3A). The formation rates of the probe drug metabolites acetaminophen and 6β-OH testosterone were determined by HPLC. The inducing effect of TSAI on CYP1A2 and CYP3A was estimated. Results: The formation rates of acetaminophen were (18. 04 ± 1.00) ng·mg·min-1 in blank control group, (43.07 ± 2.90) ng·mg-1·min-1 in phenobarbital-treated group, and (16.03 ±2.41) ng·mg-1·min-1 in TSAI group, respectively. The formation rates of 6β-OH testosterone were ( 15. 79 ± 1. 43 ), (40.86±3.32) , (17.12 ±2.65) ng·mg-1·min-1, respectively, in the 3 groups. Conclusion: TSAI has no inducing effect on CYP1A2 and CYP3A in rat liver microsomes.

  9. Protective effect of tea polyphenols against paracetamol-induced hepatotoxicity in mice is significanly correlated with cytochrome P450 suppression

    Institute of Scientific and Technical Information of China (English)

    Xia Chen; Chang-Kai Sun; Guo-Zhu Han; Jin-Yong Peng; Ying Li; Yan-Xia Liu; Yuan-Yuan Lv; Ke-Xin Liu; Qin Zhou; Hui-Jun Sun

    2009-01-01

    AIM: To investigate the hepatoprotective activity of tea polyphenols (TP) and its relation with cytochrome P450 (CYP450) expression in mice. METHODS: Hepatic CYP450 and CYPb5 levels were measured by UV-spectrophotometry in mice 2 d after intraperitoneal TP (25, 50 and 100 mg/kg per day). Then the mice were intragastricly pre-treated with TP (100, 200 and 400 mg/kg per day) for six days before paracetamol (1000 mg/kg) was given. Their acute mortality was compared with that of control mice. The mice were pre-treated with TP (100, 200, and 400 mg/kg per day) for five days before paracetamol (500 mg/kg) was given. Hepatic CYP2E1 and CYP1A2 protein and mRNA expression levels were evaluated by Western blotting, immunohistochemical staining and transcriptase-polymerase chain reaction. RESULTS: The hepatic CYP450 and CYPb5 levels in mice of TP-treated groups (100, 200 and 400 mg/kg per day) were decreased in a dose-dependent manner compared with those in the negative control mice. TP significantly attenuated the paracetamol-induced hepatic injury and dramatically reduced the mortality of paracetamol-treated mice. Furthermore, TP reduced CYP2E1 and CYP1A2 expression at both protein and mRNA levels in a dose-dependent manner. CONCLUSION: TP possess potential hepatoprotective properties and can suppress CYP450 expression.

  10. The interindividual differences in the 3-demthylation of caffeine alias CYP1A2 is determined by both genetic and environmental factors

    DEFF Research Database (Denmark)

    Rasmussen, Birgitte B; Brix, Thomas H; Kyvik, Kirsten O;

    2002-01-01

    . The mean (+/- SD) caffeine ratio was 5.9 +/- 3.4. The caffeine ratio was statistically significantly higher in men compared to women, in smoking men and women compared to non-smoking persons of the same gender and in women not taking oral contraceptives compared with women on oral contraceptives. Thus, we...... confirmed that CYP1A2 is more active in men than in women, that it is induced by smoking and inhibited by oral contraceptives. In the subsequent analysis of heritability, we included 49 monozygotic twin pairs and 34 same gender dizygotic twin pairs concordant for non-smoking and non-use of oral...... contraceptives. The intraclass correlation coefficient was 0.798 (95% confidence interval, 0.696-0.900) and 0.394 (95% confidence interval, 0.109-0.680) in the monozygotic and dizygotic twins, respectively. The correlation was statistically significantly higher (P = 0.0015) in the former compared with the latter...

  11. Impacts of diversification of cytochrome P450 on plant metabolism.

    Science.gov (United States)

    Mizutani, Masaharu

    2012-01-01

    Cytochrome P450 monooxygenases (P450s) catalyze a wide variety of monooxygenation reactions in primary and secondary metabolism in plants. The share of P450 genes in each plant genome is estimated to be up to 1%. This implies that the diversification of P450 has made a significant contribution to the ability to acquire the emergence of new metabolic pathways during land plant evolution. The P450 families conserved universally in land plants contribute to their chemical defense mechanisms. Several P450s are involved in the biosynthesis and catabolism of plant hormones. Species-specific P450 families are essential for the biosynthetic pathways of phytochemicals such as terpenoids and alkaloids. Genome wide analysis of the gene clusters including P450 genes will provide a clue to defining the metabolic roles of orphan P450s. Metabolic engineering with plant P450s is an important technology for large-scale production of valuable phytochemicals such as medicines.

  12. Toward reduction in animal sacrifice for drugs: molecular modeling of Macaca fascicularis P450 2C20 for virtual screening of Homo sapiens P450 2C8 substrates.

    Science.gov (United States)

    Rua, Francesco; Di Nardo, Giovanna; Sadeghi, Sheila J; Gilardi, Gianfranco

    2012-01-01

    Macaca fascicularis P450 2C20 shares 92% identity with human cytochrome P450 2C8, which is involved in the metabolism of more than 8% of all prescribed drugs. To date, only paclitaxel and amodiaquine, two substrate markers of the human P450 2C8, have been experimentally confirmed as M. fascicularis P450 2C20 drugs. To bridge the lack of information on the ligands recognized by M. fascicularis P450 2C20, in this study, a three-dimensional homology model of this enzyme was generated on the basis of the available crystal structure of the human homologue P450 2C8 using YASARA. The results indicated that 90.0%, 9.0%, 0.5%, and 0.5% of the residues of the P450 2C20 model were located in the most favorable, allowed, generously allowed, and disallowed regions, respectively. The root-mean-square deviation of the C-alpha superposition of the M. fascicularis P450 2C20 model with the Homo sapiens P450 2C8 was 0.074 Å, indicating a very high similarity of the two structures. Subsequently, the 2C20 model was used for in silico screening of 58 known P450 2C8 substrates and 62 inhibitors. These were also docked in the active site of the crystal structure of the human P450 2C8. The affinity of each compound for the active site of both cytochromes proved to be very similar, meaning that the few key residues that are mutated in the active site of the M. fascicularis P450 do not prevent the P450 2C20 from recognizing the same substrates as the human P450 2C8.

  13. A New Marmoset P450 4F12 Enzyme Expressed in Small Intestines and Livers Efficiently Metabolizes Antihistaminic Drug Ebastine.

    Science.gov (United States)

    Uehara, Shotaro; Uno, Yasuhiro; Yuki, Yukako; Inoue, Takashi; Sasaki, Erika; Yamazaki, Hiroshi

    2016-06-01

    Common marmosets (Callithrix jacchus) are attracting attention as animal models in preclinical studies for drug development. However, cytochrome P450s (P450s), major drug-metabolizing enzymes, have not been fully identified and characterized in marmosets. In this study, based on the four novel P450 4F genes found on the marmoset genome, we successfully isolated P450 4F2, 4F3B, 4F11, and 4F12 cDNAs in marmoset livers. Deduced amino acid sequences of the four marmoset P450 4F forms exhibited high sequence identities (87%-93%) to the human and cynomolgus monkey P450 4F homologs. Marmoset P450 4F3B and 4F11 mRNAs were predominantly expressed in livers, whereas marmoset P450 4F2 and 4F12 mRNAs were highly expressed in small intestines and livers. Four marmoset P450 4F proteins heterologously expressed in Escherichia coli catalyzed the ω-hydroxylation of leukotriene B4 In addition, marmoset P450 4F12 effectively catalyzed the hydroxylation of antiallergy drug ebastine, a human P450 2J/4F probe substrate. Ebastine hydroxylation activities by small intestine and liver microsomes from marmosets and cynomolgus monkeys showed greatly higher values than those of humans. Ebastine hydroxylation activities by marmoset and cynomolgus monkey small intestine microsomes were inhibited (approximately 60%) by anti-P450 4F antibodies, unlike human small intestine microsomes, suggesting that contribution of P450 4F enzymes for ebastine hydroxylation in the small intestine might be different between marmosets/cynomolgus monkeys and humans. These results indicated that marmoset P450 4F2, 4F3B, 4F11, and 4F12 were expressed in livers and/or small intestines and were functional in the metabolism of endogenous and exogenous compounds, similar to those of cynomolgus monkeys and humans.

  14. Arecoline inhibits the 2,3,7,8-tetrachlorodibenzo-p-dioxin-induced cytochrome P450 1A1 activation in human hepatoma cells

    Energy Technology Data Exchange (ETDEWEB)

    Chang, Eddy Essen [Lab. of Molecular Toxicology, Div. of Environmental Health and Occupational Medicine, National Health Research Institutes, 35 Keyan Road, Zhunan Town, Miaoli County 35053, Taiwan (China); Miao Zhifeng [Lab. of Molecular Toxicology, Div. of Environmental Health and Occupational Medicine, National Health Research Institutes, 35 Keyan Road, Zhunan Town, Miaoli County 35053, Taiwan (China); Lee, W.-J. [Dept. of Environmental Engineering, National Cheng Kung Univ., Tainan 701, Taiwan (China)]|[Sustainable Environment Research Center, National Cheng Kung Univ., Tainan 701, Taiwan (China); Chao, H.-R. [Dept. of Environmental Science and Engineering, National Pingtung Univ. of Science and Technology, Pingtung 912, Taiwan (China); Li, Lih-Ann [Lab. of Molecular Toxicology, Div. of Environmental Health and Occupational Medicine, National Health Research Institutes, 35 Keyan Road, Zhunan Town, Miaoli County 35053, Taiwan (China); Wang, Y.-F. [Dept. of Chemical Engineering, Chung Yuan Christian University, Chungli 320, Taiwan (China); Ko, Y.-C. [Lab. of Molecular Toxicology, Div. of Environmental Health and Occupational Medicine, National Health Research Institutes, 35 Keyan Road, Zhunan Town, Miaoli County 35053, Taiwan (China)]|[Dept. of Public Health, Kaohsiung Medical University Hospital, Kaohsiung 807, Taiwan (China); Tsai, F.-Y. [Lab. of Molecular Toxicology, Div. of Environmental Health and Occupational Medicine, National Health Research Institutes, 35 Keyan Road, Zhunan Town, Miaoli County 35053, Taiwan (China); Yeh, S.C. [Lab. of Molecular Toxicology, Div. of Environmental Health and Occupational Medicine, National Health Research Institutes, 35 Keyan Road, Zhunan Town, Miaoli County 35053, Taiwan (China); Tsou, T.-C. [Lab. of Molecular Toxicology, Div. of Environmental Health and Occupational Medicine, National Health Research Institutes, 35 Keyan Road, Zhunan Town, Miaoli County 35053, Taiwan (China)]. E-mail: tctsou@nhri.org.tw

    2007-07-19

    In the present study, we investigated the effect of arecoline, a major areca nut alkaloid, on the 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD)-induced activation of cytochrome P4501A1 (CYP1A1) in a human hepatoma cell line Huh-7. We treated Huh-7 cells with 10 nM TCDD in the presence of different concentrations of arecoline (50-300 {mu}M). Our results indicated that arecoline attenuated the TCDD-induced CYP1A1 enzyme activation with an inhibitory effect on cell proliferation. By using real-time RT-PCR, we demonstrated that arecoline inhibited the TCDD-induced activations of CYP1A1 and AhR repressor (AhRR) mRNA expression in a similar pattern. Our results revealed that arecoline inhibited AhR mRNA expression with no direct effect on CYP1A1 enzyme activity. Therefore, in our present study, the observed inhibitory effect of arecoline on CYP1A1 activation was not due to the up-regulation of AhRR or direct inhibitory effect on CYP1A1. Taken together, here we have demonstrated that arecoline attenuates the TCDD-induced CYP1A1 activation mainly via down-regulation of AhR expression in human hepatoma cells, suggesting the possible involvement of arecoline in the AhR-mediated metabolism of environmental toxicants in liver.

  15. Examination of metabolic pathways and identification of human liver cytochrome P450 isozymes responsible for the metabolism of barnidipine, a calcium channel blocker.

    Science.gov (United States)

    Teramura, T; Fukunaga, Y; Van Hoogdalem, E J; Watanabe, T; Higuchi, S

    1997-09-01

    1. In a human liver microsomal system, barnidipine was converted into three primary metabolites, an N-debenzylated product (M-1), a hydrolyzed product of the benzyl-pyrrolidine ester (M-3) and an oxidized product of the dihydropyridine ring (M-8). 2. Involvement of CYP3A in the three primary metabolic pathways was revealed by the following studies: (a) inhibition of CYP3A, (b) a correlation study using 10 individual human liver microsomes and (c) cDNA-expression studies. The secondary metabolites, M-2 and M-4 (pyridine forms of M-1 and M-3), were most likely generated from M-8 but were unlikely from M-1 or M-3. Involvement of CYP3A in the secondary pathways of metabolism is also suggested. 3. The possibility of interactions between barnidipine and coadministered drugs was examined in vitro. The formation rate of the primary metabolites was little affected by warfarin, theophylline, phenytoin, diclofenac and amitriptyline at concentrations of 200 microM, but was inhibited by glibenclamide, simvastatin and cyclosporin A. IC50 for the latter drugs was estimated to be > 200, 200 and 20 microM respectively, which was roughly > 200, 6000 and 50 times higher than their respective therapeutic plasma levels, suggesting that interactions with cyclosporin A, a CYP3A inhibitor, are of possible clinical relevance.

  16. Arecoline inhibits the 2,3,7,8-tetrachlorodibenzo-p-dioxin-induced cytochrome P450 1A1 activation in human hepatoma cells.

    Science.gov (United States)

    Chang, Eddy Essen; Miao, Zhi-Feng; Lee, Wen-Jhy; Chao, How-Ran; Li, Lih-Ann; Wang, Ya-Fen; Ko, Ying-Chin; Tsai, Feng-Yuan; Yeh, Szu Ching; Tsou, Tsui-Chun

    2007-07-19

    In the present study, we investigated the effect of arecoline, a major areca nut alkaloid, on the 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD)-induced activation of cytochrome P4501A1 (CYP1A1) in a human hepatoma cell line Huh-7. We treated Huh-7 cells with 10nM TCDD in the presence of different concentrations of arecoline (50-300 microM). Our results indicated that arecoline attenuated the TCDD-induced CYP1A1 enzyme activation with an inhibitory effect on cell proliferation. By using real-time RT-PCR, we demonstrated that arecoline inhibited the TCDD-induced activations of CYP1A1 and AhR repressor (AhRR) mRNA expression in a similar pattern. Our results revealed that arecoline inhibited AhR mRNA expression with no direct effect on CYP1A1 enzyme activity. Therefore, in our present study, the observed inhibitory effect of arecoline on CYP1A1 activation was not due to the up-regulation of AhRR or direct inhibitory effect on CYP1A1. Taken together, here we have demonstrated that arecoline attenuates the TCDD-induced CYP1A1 activation mainly via down-regulation of AhR expression in human hepatoma cells, suggesting the possible involvement of arecoline in the AhR-mediated metabolism of environmental toxicants in liver.

  17. Cytochrome P450-catalyzed binding of 3-methylsulfonyl-DDE and o,p'-DDD in human adrenal zona fasciculata/reticularis.

    Science.gov (United States)

    Lindhe, Orjan; Skogseid, Britt; Brandt, Ingvar

    2002-03-01

    3-Methylsulfonyl-2,2'-bis(4-chlorophenyl)-1,1'-dichloroethene (MeSO(2)-DDE) is a potent, tissue-specific toxicant that induces necrosis of the adrenal zona fasciculata following a local CYP11B1-catalyzed activation to a reactive intermediate in mice. Autoradiography was used to examine CYP11B1-catalyzed binding of MeSO(2)-[(14)C]DDE and the adrenocorticolytic drug 2-(2-chlorophenyl)-2-(4-chlorophenyl)-1,1-dichlorethane; (o,p'-[(14)C]DDD, Mitotane, Lysodren) in human adrenal tissue slice culture. Both compounds gave rise to a selective binding in the one sample of normal adrenal zona fasciculata/reticularis, leaving zona glomerulosa and the adrenal medulla devoid of binding. Addition of the CYP11B1 selective inhibitor metyrapone (50 microM) reduced MeSO(2)-[(14)C]DDE binding below the detection limit, whereas o,p'-[(14)C]DDD binding was reduced only by 42%. Selective binding of MeSO(2)-[(14)C]DDE and o,p'-[(14)C]DDD was also observed in an aldosterone-producing adrenocortical carcinoma and in a nonfunctional adrenocortical hyperplasia. Exposure of slices from the normal adrenal cortex to MeSO(2)-DDE (25 microM) resulted in an increased accumulation of 11-deoxycorticosterone, 11-deoxycortisol and androstenedione in the medium, and exposure to o,p'-DDD (25 microM) did not alter the steroid secretion pattern. No histological changes were found in either MeSO(2)-DDE- or o,p'-DDD-exposed slices, compared with nonexposed slices. We suggest that MeSO(2)-DDE might act as a potent adrenocorticolytic agent in humans. Further studies are needed to establish the usefulness of MeSO(2)-DDE as a possible alternative for the treatment of adrenocortical hypersecretion and tumor growth.

  18. Altered expression of cytochrome P450 and possible correlation with preneoplastic changes in early stage of rat hepatocarcinogenesis

    Institute of Scientific and Technical Information of China (English)

    Lin-lin LIU; Li-kun GONG; Xin-ming QI; Yan CAI; Hui WANG; Xiong-fei WU; Ying XIAO; Jin REN

    2005-01-01

    Aim: Correlation of cytochrome P450 (CYPs) with preneoplastic changes in the early stage of hepatocarcinogenesis is still unclear. To detect the expression of carcinogen-metabolizing related microsomal P450 enzymes, namely the CYP1A1,CYP1A2, CYP2B 1/2, CYP2E1, and CYP3A, we performed the medium-term bioassay of Ito's model in Sprague-Dawley rats. Methods: The amount and activity of CYP were assessed by biochemical and immunohistochemical methods in week 8.The correlation between CYP expression and microsomal oxidative stress was investigated by comparing the generation of microsomal lipid peroxidation in the presence or absence of specific CYP inhibitor. Results: In the DEN-2-AAF and 2-AAF alone groups, the expression of CYP1A1 and CYP2E1 were up-regulated and the expression of CYP2B 1/2 and CYP1A2 were quite the contrary. Strong staining of CYP2E1 and CYP2B1/2 was found around the centrolobular vein and weak staining in the altered hepatic foci revealed by immunohistochemical procedure.There was no significant change in the activity of CYP3A among the 4 groups.Altered hepatic tissue bore more microsomal NADPH (nicotinamide adenine dimucleotide phosphate,reduced form)-dependent lipid peroxidation than normal tissue. And the difference among the 4 groups disappeared when CYP2E1 was inhibited. More microsomal lipid peroxidation was generated when incubated with CYP1A inhibitor α-naphthoflavone. Conclusion: CYP altered their expression levels and these alterations can play important roles in the alteration of cell redox status of preneoplastic tissue in the early stage of hepatocarcinogenesis.

  19. 非那西丁探针法动态观测非酒精性脂肪肝大鼠发病进程中的CYP1A2活性%Dynamic Observation of CYP1A2 Activity in Nonalcoholic Fatty Liver Disease Process of Rats by Phenacetin Probe Method

    Institute of Scientific and Technical Information of China (English)

    刘莹; 金涌; 蒋培培; 吴德敏; 方慧子; 周静婷; 季俊虬

    2012-01-01

    OBJECTIVE: To observe the activity of CYP450 in nonalcoholic fatty liver disease process of rats by phenacetin probe method dynamically. METHODS: Nonalcoholic fatty liver rat model was established, and probe drugs were given at Oth, 7th, 9th, 11th, 13th, 15th, 17th week and at the same time urine was collected. The metabolism index of phenacetin metabolite acetaminophen was determined to investigate the activity of CYP1A2 acetaminophen with normal rats as control. HPLC method was used. The determination was performed on Hypersil ODS column with mobile phase consisted of methanol-water (12.5:87.5) at the flow rate of 1.0 mL·min‐1. The detection wavelength was set at 254 nm. RESULTS: The metabolism of acetaminophen per unit body weight reached the peak at 9th week, which is higher than at Oth week and normal group ((15.02 ± 3.12), (10.03 ± 3.60), (9.96±4.00) mg·kg‐1), and then decreased gradually, i.e. the activity of CYP1A2 increased firstly and then decreased. CONCLUSION: This method is simple and reliable for the determination of acetaminophen in rats urine and CYP1A2 activity research.%目的:建立探针法动态观测非酒精性脂肪肝大鼠发病进程中细胞色素(CY)P150酶系的活性.方法:制备非酒精性脂肪肝大鼠模型,分别于造模后第0、7、9、11、13、15、17周给予探针药物非那西丁并收集尿液,检测其中非那西丁代谢产物对乙酰氨基酚的各代谢指标以考察CYP1A2的活性变化情况,同时设立正常大鼠组为对照.含量检测采用高效液相色谱法,色谱柱为HypersilODS,流动相为甲醇-水(12.5∶87.5),流速为1.0mL·min-1,检测波长为254 nm.结果:对乙酰氨基酚的单位体重代谢量在第9周时达到最高,明显高于第0周和正常组(( 15.02±3.12)、( 10.03±3.60)、(9.96±4.00) mg·kg-1),随后又逐渐降低,即CYP1A2的活性先升高后降低.结论:建立的探针法简便可靠,适用于大鼠尿中对乙酰氨基酚的测定以及CYP1A2活性的研究.

  20. Effect of Flavonoids on Glutathione Level, Lipid Peroxidation and Cytochrome P450 CYP1A1 Expression in Human Laryngeal Carcinoma Cell Lines

    Directory of Open Access Journals (Sweden)

    Lidija Vuković

    2007-01-01

    Full Text Available Flavonoids are phytochemicals exhibiting a wide range of biological activities, among which are antioxidant activity, the ability to modulate activity of several enzymes or cell receptors and possibility to interfere with essential biochemical pathways. Using human laryngeal carcinoma HEp2 cells and their drug-resistant CK2 subline, we examined the effect of five flavonoids, three structurally related flavons (quercetin, fisetin, and myricetin, one flavonol (luteolin and one glycosilated flavanone (naringin for: (i their ability to inhibit mitochondrial dehydrogenases as an indicator of cytotoxic effect, (ii their influence on glutathione level, (iii antioxidant/prooxidant effects and influence on cell membrane permeability, and (iv effect on expression of cytochrome CYP1A1. Cytotoxic action of the investigated flavonoids after 72 hours of treatment follows this order: luteolin>quercetin>fisetin>naringin>myricetin. Our results show that CK2 were more resistant to toxic concentrations of flavonoids as compared to parental cells. Quercetin increased the total GSH level in both cell lines. CK2 cells are less perceptible to lipid peroxidation and damage caused by free radicals. Quercetin showed prooxidant effect in both cell lines, luteolin only in HEp2 cells, whereas other tested flavonoids did not cause lipid peroxidation in the tested cell lines. These data suggest that the same compound, quercetin, can act as a prooxidant, but also, it may prevent damage in cells caused by free radicals, due to the induction of GSH, by forming less harmful complex. Quercetin treatment damaged cell membranes in both cell lines. Fisetin caused higher cell membrane permeability only in HEp2 cells. However, these two compounds did not enhance the damage caused by hydrogen peroxide. Quercetin, naringin, myricetin and fisetin increased the expression of CYP1A1 in both cell lines, while luteolin decreased basal level of CYP1A1 only in HEp2 cells. In conclusion, small

  1. Transfer of PCBs via lactation simultaneously induces the expression of P450 isoenzymes and the protooncogenes c-Ha-ras and c-raf in neonates.

    Science.gov (United States)

    Borlak, J T; Scott, A; Henderson, C J; Jenke, H J; Wolf, C R

    1996-02-23

    At the first day of lactation, maternal rats were injected with a single i.p. dose of 100 or 250 mg/kg body weight of a mixture of polychlorinated biphenyls (Aroclor 1254). This treatment caused significant increases in both material and neonatal hepatic cytochrome P-450, cytochrome b5, and cytochrome-c-(P-450) reductase. Transfer of PCBs via lactation resulted in significant increases in hepatic enzyme activities catalysed by neonatal CYP1A1, CYP1A2, CYP2B1, CYP3A1, and CYP2E1 using a variety of substrates. In contrast, the metabolism of dimethylnitrosamine and aminopyrine was only marginally (up to 2-fold) increased in maternal animals four days post treatment. Further measurements showed significant increases in maternal and neonatal epoxide hydrolase, glutathione-S-transferase, and UDP-glucuronyl transferase activities, thus suggesting a coordinated response for an induction of CYP1A1, CYP1A2, CYP2A1, CYP2B1, CYP2E1, CYP3A1, and CYP4A1 in both maternal and neonatal CYP2C6, and at the higher dose the expression of neonatal CYP2E1 was significantly reduced. Northern blot analysis provided further evidence for significant increases in maternal and neonatal hepatic CYP1A1, CYP1A2, CYP2B1, and CYP2E1 mRNA, but reduced amounts of CYP2C7 and CYP4A1 mRNA. Additional Northern blot hybridization experiments may suggest an increased expression of the protooncogenes c-Ha-ras and c-raf in the mother and the neonate upon treatment of maternal rats with Aroclor 1254. Lactation itself may result in an increased expression of the latter protooncogenes, but the mRNA of the protooncogenes c-erb A and c-erb B was not detected in any of the tissues examined.

  2. Influences of V5-epitope tag on the metabolic activation of AFB1 by human cytochrome P450 2A13

    Institute of Scientific and Technical Information of China (English)

    Shoulin Wang; Xiaoyang He; Xinru Wang; Junyan Hong

    2006-01-01

    Objective: To explore the impact of V5-epitope tag inserted in the commercial pcDNA5/FRT/V5-His TOPO expression vector on the metabolic activation of AFB1 by human CYP2A13. Methods: A C-terminal 6×Histag was first introduced into CYP2A13 cDNA by PCR and subsequently transferred into the expressing vector pcDNA5/FRT. Another commercial pcDNA5/FRT/V5-His TOPO expression vector was used to develop the construct directly via PCR. Both of the constructs were then transfected into Flp-In CHO and allowed for the stable expression of CYP2A13. The mouse CYP2A5 and the vector alone were used as positive and negative control, respectively. The presence of CYP2A5 and CYP2A13 cDNA and their protein expression in the stable transfectant cells were determined by immunoblotting assay using a monoclonal antibody against 6×Histag. The AFB1-induced cytotoxicity in these tranfected CHO cells were conducted by MTS assay and the IC50 of cell viability was used to compare the CYP enzyme metabolic activity in AFB1 metabolism among these cells. Results: In accordance with the Flp-In system working mechanism, all the transfectant cells presented same protein expression level. The CHO cells expressing CYP2A5 was more sensitive to AFB1 treatment than those cells expressing CYP2A13, there was about 30-fold IC50 difference between the two cells (2.1 nmol/L vs 58 nmol/L). Interestingly, CYP2A13 fused with V5-Histag had the lost of metabolic activity to AFB1 than that fused with Histag alone, the IC50 of the viability in CHO-2A13-His-V5 cells was about 20-fold less than CHO-2A13-His (>1 000 nmol/L vs 58 nmol/L). However, there was no change between CYP2A5 fused with V5-Histag and Histag alone (2.4 nmol/L vs 2.1 nmol/L). Conclusion: The results demonstrate that CYP2A13 fused with V5-epitope has a significant impact on its metabolic activation to AFB1, which indicated that it should be careful to select a new expressing vector for evaluating the enzyme activity in carcinogen metabolism.

  3. Sequences promoting the transcription of the human XA gene overlapping P450c21A correctly predict the presence of a novel, adrenal-specific, truncated form of tenascin-X

    Energy Technology Data Exchange (ETDEWEB)

    Tee, Meng Kian; Thomson, A.A.; Bristow, J.; Miller, W.L. [Univ. of California, San Francisco, CA (United States)

    1995-07-20

    A compact region in the human class III major histocompatibility locus contains the human genes for the fourth component of human complement (C4) and steroid 21-hydroxylase (P450c21) in one transcriptional orientation, while the gene for the extracellular matrix protein tenascin-X (TN-X) overlaps the last exon of P450c21 on the opposite strand of DNA in the opposite transcriptional orientation. This complex locus is duplicated into A and B loci, so that the organization is 5{prime}-C4A-21A-XA-C4B-21B-XB-3{prime}. Although this duplication event truncated the 65-kb X(B) gene to a 4.5-kb XA gene, the XA gene is transcriptionally active in the adrenal cortex. To examine the basis of the tissue-specific expression of XA and C4B, we cloned the 1763-bp region that lies between the cap sites for XA and C4B and analyzed its promoter activity in both the XA and the C4 orientations. Powerful, liver-specific sequences lie within the first 75 to 138 bp from the C4B cap site, and weaker elements lie within 128 bp of the XA cap site that function in both liver and adrenal cells. Because these 128 bp upstream from the XA cap site are perfectly preserved in the XB gene encoding TN-X, we sought to determine whether a transcript similar to XA arises within the SB gene. RNase protection assays, cDNA cloning, and RT/PCR show that adrenal cells contain a novel transcript, termed short XB (XB-S), which has the same open reading frame as TN-X. Cell-free translation and immunoblotting show that this transcript encodes a novel 74-kDa XB-S protein that is identical to the carboxy-terminal 673 residues of TN-X. Because this protein consists solely of fibronectin type III repeats and a fibrinogen-like domain, it appears to correspond to an evolutionary precursor of the tenascin family of extracellular matrix proteins. 40 refs., 6 figs.

  4. Induction of liver cytochrome P450 1A2 expression by flutamide in rats

    Institute of Scientific and Technical Information of China (English)

    Hai-xue WANG; Xiao LIU; Chang-jiang XU; Xiao-chao MA; Jian-er LONG; Duan LI

    2005-01-01

    Aim: To investigate the modulation of liver cytochrome P4501A2 (CYP1A2) expression by giving flutamide to adult rats. Methods: Rats were given 50, 100, and200 mg/kgpo of flutamide for 2 weeks. Liver CYP1A2 mRNA was measured using reverse transcription-polymerase chain reaction. CYP1A2 protein was detected using immunoblotting. CYP1A2 activity was assayed using high performance liquid chromatography, with caffeine as the CYP1A2 substrate. Results: CYP1A2mRNA levels after flutamide treatment at 100 mg/kg and 200 mg/kg were, respectively,1.86 and 3.11-fold higher than those of the control. Correspondingly, CYP1A2protein increased 1.78 and 2.89-fold and CYP1A2 activity increased approximately1.65 and 2.83-fold, respectively, relative to controls. Flutamide treatment at 50mg/kg had no significant effect on CYP1A2 mRNA, protein, or enzyme activity.Conclusion: Giving rats flutamide induced liver CYP1A2 expression in a dosedependent manner.

  5. Engineering Macaca fascicularis cytochrome P450 2C20 to reduce animal testing for new drugs.

    Science.gov (United States)

    Rua, Francesco; Sadeghi, Sheila J; Castrignanò, Silvia; Di Nardo, Giovanna; Gilardi, Gianfranco

    2012-12-01

    In order to develop in vitro methods as an alternative to P450 animal testing in the drug discovery process, two main requisites are necessary: 1) gathering of data on animal homologues of the human P450 enzymes, currently very limited, and 2) bypassing the requirement for both the P450 reductase and the expensive cofactor NADPH. In this work, P450 2C20 from Macaca fascicularis, homologue of the human P450 2C8 has been taken as a model system to develop such an alternative in vitro method by two different approaches. In the first approach called "molecular Lego", a soluble self-sufficient chimera was generated by fusing the P450 2C20 domain with the reductase domain of cytochrome P450 BM3 from Bacillus megaterium (P450 2C20/BMR). In the second approach, the need for the redox partner and also NADPH were both obviated by the direct immobilization of the P450 2C20 on glassy carbon and gold electrodes. Both systems were then compared to those obtained from the reconstituted P450 2C20 monooxygenase in presence of the human P450 reductase and NADPH using paclitaxel and amodiaquine, two typical drug substrates of the human P450 2C8. The K(M) values calculated for the 2C20 and 2C20/BMR in solution and for 2C20 immobilized on electrodes modified with gold nanoparticles were 1.9 ± 0.2, 5.9 ± 2.3, 3.0 ± 0.5 μM for paclitaxel and 1.2 ± 0.2, 1.6±0.2 and 1.4 ± 0.2 μM for amodiaquine, respectively. The data obtained not only show that the engineering of M. fascicularis did not affect its catalytic properties but also are consistent with K(M) values measured for the microsomal human P450 2C8 and therefore show the feasibility of developing alternative in vitro animal tests. Copyright © 2012 Elsevier Inc. All rights reserved.

  6. Effect of a New Prokinetic Agent DA-9701 Formulated with Corydalis Tuber and Pharbitidis Semen on Cytochrome P450 and UDP-Glucuronosyltransferase Enzyme Activities in Human Liver Microsomes

    Directory of Open Access Journals (Sweden)

    Hye Young Ji

    2012-01-01

    Full Text Available DA-9701 is a new botanical drug composed of the extracts of Corydalis tuber and Pharbitidis semen, and it is used as an oral therapy for the treatment of functional dyspepsia in Korea. The inhibitory potentials of DA-9701 and its component herbs, Corydalis tuber and Pharbitidis semen, on the activities of seven major human cytochrome P450 (CYP enzymes and four UDP-glucuronosyltransferase (UGT enzymes in human liver microsomes were investigated using liquid chromatography-tandem mass spectrometry. DA-9701 and Corydalis tuber extract slightly inhibited UGT1A1-mediated etoposide glucuronidation, with 50% inhibitory concentration (IC50 values of 188 and 290 μg/mL, respectively. DA-9701 inhibited CYP2D6-catalyzed bufuralol 1′-hydroxylation with an inhibition constant (Ki value of 6.3 μg/mL in a noncompetitive manner. Corydalis tuber extract competitively inhibited CYP2D6-mediated bufuralol 1′-hydroxylation, with a Ki value of 3.7 μg/mL, whereas Pharbitidis semen extract showed no inhibition. The volume in which the dose could be diluted to generate an IC50 equivalent concentration (volume per dose index value of DA-9701 for inhibition of CYP2D6 activity was 1.16 L/dose, indicating that DA-9701 may not be a potent CYP2D6 inhibitor. Further clinical studies are warranted to evaluate the in vivo extent of the observed in vitro interactions.

  7. Flower colour and cytochromes P450.

    Science.gov (United States)

    Tanaka, Yoshikazu; Brugliera, Filippa

    2013-02-19

    Cytochromes P450 play important roles in biosynthesis of flavonoids and their coloured class of compounds, anthocyanins, both of which are major floral pigments. The number of hydroxyl groups on the B-ring of anthocyanidins (the chromophores and precursors of anthocyanins) impact the anthocyanin colour, the more the bluer. The hydroxylation pattern is determined by two cytochromes P450, flavonoid 3'-hydroxylase (F3'H) and flavonoid 3',5'-hydroxylase (F3'5'H) and thus they play a crucial role in the determination of flower colour. F3'H and F3'5'H mostly belong to CYP75B and CYP75A, respectively, except for the F3'5'Hs in Compositae that were derived from gene duplication of CYP75B and neofunctionalization. Roses and carnations lack blue/violet flower colours owing to the deficiency of F3'5'H and therefore lack the B-ring-trihydroxylated anthocyanins based upon delphinidin. Successful redirection of the anthocyanin biosynthesis pathway to delphinidin was achieved by expressing F3'5'H coding regions resulting in carnations and roses with novel blue hues that have been commercialized. Suppression of F3'5'H and F3'H in delphinidin-producing plants reduced the number of hydroxyl groups on the anthocyanidin B-ring resulting in the production of monohydroxylated anthocyanins based on pelargonidin with a shift in flower colour to orange/red. Pelargonidin biosynthesis is enhanced by additional expression of a dihydroflavonol 4-reductase that can use the monohydroxylated dihydrokaempferol (the pelargonidin precursor). Flavone synthase II (FNSII)-catalysing flavone biosynthesis from flavanones is also a P450 (CYP93B) and contributes to flower colour, because flavones act as co-pigments to anthocyanins and can cause blueing and darkening of colour. However, transgenic plants expression of a FNSII gene yielded paler flowers owing to a reduction of anthocyanins because flavanones are precursors of anthocyanins and flavones.

  8. In vitro interaction cocktail assay for nine major cytochrome P450 enzymes with 13 probe reactions and a single LC/MSMS run: analytical validation and testing with monoclonal anti-CYP antibodies.

    Science.gov (United States)

    Tolonen, Ari; Petsalo, Aleksanteri; Turpeinen, Miia; Uusitalo, Jouko; Pelkonen, Olavi

    2007-07-01

    A sensitive and rugged LC/MSMS method was developed for a comprehensive in vitro metabolic interaction screening assay with N-in-1 approach reported earlier. A cocktail consisting of ten cytochrome P450 (CYP)-selective probe substrates with known kinetic, metabolic and interaction properties in vivo was incubated in a pool of human liver microsomes, and metabolites of melatonin (CYP1A2), coumarin (CYP2A6), bupropion (CYP2B6), amodiaquine (CYP2C8) tolbutamide (CYP2C9), omeprazole (CYP2C19 and CYP3A4), dextromethorphan (CYP2D6), chlorzoxazone (CYP2E1), midazolam (CYP3A4) and testosterone (CYP3A4) were simultaneously analysed with a single LC/MSMS run. Altogether, 13 metabolites and internal standard phenacetin were analysed in multiple reaction mode. Polarity switching mode was utilized to acquire negative ion mode electrospray data for hydroxychlorzoxazone and positive ionization data for the rest of the analytes. Fast gradient elution was applied, giving total injection cycle of 8 min. The method was modified for two different LC/MSMS systems, and was validated for linear range, detection limit, accuracy and precision for each metabolite. In addition, cocktail inhibition system was further tested using monoclonal anti-CYP antibodies as inhibitors for each probe reaction. Copyright (c) 2007 John Wiley & Sons, Ltd.

  9. Human liver cytochrome P450 3A4 ubiquitination: molecular recognition by UBC7-gp78 autocrine motility factor receptor and UbcH5a-CHIP-Hsc70-Hsp40 E2-E3 ubiquitin ligase complexes.

    Science.gov (United States)

    Wang, YongQiang; Kim, Sung-Mi; Trnka, Michael J; Liu, Yi; Burlingame, A L; Correia, Maria Almira

    2015-02-06

    CYP3A4 is an abundant and catalytically dominant human liver endoplasmic reticulum-anchored cytochrome P450 enzyme engaged in the biotransformation of endo- and xenobiotics, including >50% of clinically relevant drugs. Alterations of CYP3A4 protein turnover can influence clinically relevant drug metabolism and bioavailability and drug-drug interactions. This CYP3A4 turnover involves endoplasmic reticulum-associated degradation via the ubiquitin (Ub)-dependent 26 S proteasomal system that relies on two highly complementary E2 Ub-conjugating-E3 Ub-ligase (UBC7-gp78 and UbcH5a-C terminus of Hsc70-interacting protein (CHIP)-Hsc70-Hsp40) complexes, as well as protein kinases (PK) A and C. We have documented that CYP3A4 Ser/Thr phosphorylation (Ser(P)/Thr(P)) by PKA and/or PKC accelerates/enhances its Lys ubiquitination by either of these E2-E3 systems. Intriguingly, CYP3A4 Ser(P)/Thr(P) and ubiquitinated Lys residues reside within the cytosol-accessible surface loop and/or conformationally assembled acidic Asp/Glu clusters, leading us to propose that such post-translational Ser/Thr protein phosphorylation primes CYP3A4 for ubiquitination. Herein, this possibility was examined through various complementary approaches, including site-directed mutagenesis, chemical cross-linking, peptide mapping, and LC-MS/MS analyses. Our findings reveal that such CYP3A4 Asp/Glu/Ser(P)/Thr(P) surface clusters are indeed important for its intermolecular electrostatic interactions with each of these E2-E3 subcomponents. By imparting additional negative charge to these Asp/Glu clusters, such Ser/Thr phosphorylation would generate P450 phosphodegrons for molecular recognition by the E2-E3 complexes, thereby controlling the timing of CYP3A4 ubiquitination and endoplasmic reticulum-associated degradation. Although the importance of phosphodegrons in the CHIP targeting of its substrates is known, to our knowledge this is the first example of phosphodegron involvement in gp78-substrate

  10. Cytochrome P450 Drug Metabolizing Enzymes in Roma Population Samples: Systematic Review of the Literature.

    Science.gov (United States)

    Szalai, Renata; Hadzsiev, Kinga; Melegh, Bela

    2016-01-01

    The cytochrome P450 drug metabolizing enzymes are highly polymorphic and show inter-individual differences in variability in drug response, which varies widely also with ethnicity. This study aims to summarize the available data on genetic polymorphisms associated with cytochrome enzymes conducted on Roma populations. Our goal was to compare the frequency of the variant alleles, genotypes and predicted phenotypes with corresponding rates from other populations. We carried out a systematic review including the papers published on the pharmacogenetically relevant variants of cytochrome P450 genes related to Roma population. The study was performed using several articles, websites and databases, including PubMed, Ensembl, dbSNP, HapMap and 1000 Genomes Project. This review attempts to summarize and discuss our current knowledge about the frequency distribution of the ever investigated 20 allelic variants of 9 cytochrome genes (CYP1A2, CYP1B1, CYP2B6, CYP2C9, CYP2C19, CYP2C8, CYP2D6, CYP3A5, CYP4F2) in Roma DNA samples and compare them with other populations. Differences between Roma and Hungarian samples are reported for 7 variant genotypes. CYP2C9 *2/*3 and CYP2C19 *2/*2 genotypes showed more than 3-fold differences. Additional differences are displayed for allele frequency of 7 variants (rs762551, rs3745274, rs1058930, rs1065852, rs3892097, rs1057910 and rs4244285) in Roma population samples. The interethnic variability in clinically relevant genetic polymorphisms of drug metabolizing enzymes, which may explain distinct drug response, highlights the need to allow for the ancestry of participants in pharmacogenetic studies.

  11. Effects of Pristane on Cytochrome P450 Isozyme Expression in Rat Tissues

    Directory of Open Access Journals (Sweden)

    Marvin A. Cuchens

    2005-04-01

    Full Text Available Chemical carcinogenesis studies are powerful tools to obtain information on potential mechanisms of chemical factors for malignancies. In this study Western blot analyses, using monoclonal antibodies specific for three different cytochrome P450 (CYP isozymes (CYP1A1, CYP1A2 and CYP2B, were employed to examine the effect(s of 3-methylcholanthrene and/or pristane (2,6,10,14-tetramethylpentadecane on the basal and inducible levels of expression of CYP proteins within Copenhagen rat tissues. Pristane exposure led to tissue specific differences in the CYP isozymes expressed and elicited increased CYP protein expression over 3-methylcholanthrene induced levels in microsomes isolated from liver, Peyer's Patches, and thymus. Within the context of the chemical carcinogenesis model employed in this study, these observations correlated with the induction of B-cell malignancies by low doses of 3-methylcholanthrene and of thymic lymphomas by a high 3-methylcholanthrene dose. The data suggest that pristane treatment affects CYP isozyme expression. This pristane-mediated effect clearly could be a contributing factor in the chemical carcinogenesis of the previously observed lymphoid malignancies, and a possible basis for the tumor enhancing effects of pristane.

  12. Carbonated soft drinks alter hepatic cytochrome P450 isoform expression in Wistar rats

    Science.gov (United States)

    Alkhedaide, Adel; Soliman, Mohamed Mohamed; Ibrahim, Zein Shaban

    2016-01-01

    The aim of the current study was to examine the effects of chronic consumption of soft drinks (SDs) on hepatic oxidative stress and cytochrome P450 enzymes (CYPs) expression in the livers of Wistar rats. For 3 consecutive months, the rats had free access to three different soft drinks, Coca-Cola, Pepsi-Cola and 7-UP. The rats were subsequently compared with control group rats that had consumed water. Blood and hepatic tissue samples were assayed for the changes in antioxidants, liver function biomarkers and hepatic gene expression for different isoforms of hepatic CYP. The results indicated that SD consumption (SDC) decreased serum antioxidant levels and increased malondialdehyde secretion, and increased liver biomarkers (glutamate pyruvate transaminase and glutamate oxaloacetate). SD induced alterations in mRNA expression of hepatic antioxidants and cytochrome isoforms. The expression of peroxidase, catalase, CYP1A2, CYP3A2 and CYP2C11 in the liver were upregulated following SDC. By contrast, CYP2B1 was downregulated after 3 months of SDC in liver tissue samples. Thus, the present findings indicate that SDs induced oxidative stress in the liver of Wistar rats and for the first time, to the best of our knowledge, indicate that SDC disrupts hepatic CYP enzymes that may affect drug metabolism. Therefore, drug-dosing programs should be carefully designed to take these novel findings into consideration for the treatment of diseases. PMID:27882225

  13. Cytochrome P450 1 enzyme inhibition and anticancer potential of chromene amides from Amyris plumieri.

    Science.gov (United States)

    Badal, S; Williams, S A; Huang, G; Francis, S; Vedantam, P; Vendantam, P; Dunbar, O; Jacobs, H; Tzeng, T J; Gangemi, J; Delgoda, R

    2011-03-01

    Cytochrome P450 (CYP) enzyme inhibitory properties of six chromenylated amide compounds (CAs) from Amyris plumieri are described. Inhibition of CYP microsomes (CYP1A1, CYP1A2, CYP1B1, CYP2D6, CYP3A4 and CYP2C19) was monitored using a fluorescent assay. Potent inhibition was found against CYP1A1 with IC(50) and K(i) for CA1 (acetamide), being the lowest at 1.547 ± 1.0 μM and 0.37 μM respectively, displaying non-competitive kinetics. The selectivity for CYP1A1 was increased in CA3 (butanamide), which also exhibited cytotoxicity against breast cancer cells, MCF7 with an IC(50) of 47.46 ± 1.62 μM. Structure-activity relationship studies provide insight at a molecular level for CAs with implications in chemoprevention and chemotherapy. Copyright © 2010 Elsevier B.V. All rights reserved.

  14. Inhibitory effects of kale ingestion on metabolism by cytochrome P450 enzymes in rats.

    Science.gov (United States)

    Yamasaki, Izumi; Yamada, Masayoshi; Uotsu, Nobuo; Teramoto, Sachiyuki; Takayanagi, Risa; Yamada, Yasuhiko

    2012-01-01

    Kale (Brassica oleracea L. var acephala DC) is a leafy green vegetable belonging to the cabbage family (Brassicaceae) that contains a large amount of health-promoting phytochemicals. There are any reports about the effects of kale ingestion on the chemoprevention function and mechanism, but the interactions between kale and drugs have not been researched. We investigated the effects of kale intake on cytochrome P450 (CYP) metabolism by using cocktail probe drugs, including midazolam (for CYP3A4), caffeine (for CYP1A2), dextromethorphan (for CYP2D6), tolbutamide (for CYP2C9), omeprazole (for CYP2C19), and chlorzoxazone (for CYP2E1). Cocktail drugs were administered into rats treated with kale and cabbage (2000 mg/kg) for a week. The results showed that kale intake induced a significant increase in plasma levels and the AUC of midazolam, caffeine, and dextromethorphan. In addition, the plasma concentration and AUC of omeprazole tended to increase. Additionally, no almost differences in the mRNA expression levels of CYP enzymes in the liver were observed. In conclusion, kale ingestion was considered to have an inhibitory effect on the activities of CYP3A4, 1A2, 2D6, and 2C19 for a reason competitive inhibition than inhibitory changes in the mRNA expressions.

  15. Carbonated soft drinks alter hepatic cytochrome P450 isoform expression in Wistar rats.

    Science.gov (United States)

    Alkhedaide, Adel; Soliman, Mohamed Mohamed; Ibrahim, Zein Shaban

    2016-11-01

    The aim of the current study was to examine the effects of chronic consumption of soft drinks (SDs) on hepatic oxidative stress and cytochrome P450 enzymes (CYPs) expression in the livers of Wistar rats. For 3 consecutive months, the rats had free access to three different soft drinks, Coca-Cola, Pepsi-Cola and 7-UP. The rats were subsequently compared with control group rats that had consumed water. Blood and hepatic tissue samples were assayed for the changes in antioxidants, liver function biomarkers and hepatic gene expression for different isoforms of hepatic CYP. The results indicated that SD consumption (SDC) decreased serum antioxidant levels and increased malondialdehyde secretion, and increased liver biomarkers (glutamate pyruvate transaminase and glutamate oxaloacetate). SD induced alterations in mRNA expression of hepatic antioxidants and cytochrome isoforms. The expression of peroxidase, catalase, CYP1A2, CYP3A2 and CYP2C11 in the liver were upregulated following SDC. By contrast, CYP2B1 was downregulated after 3 months of SDC in liver tissue samples. Thus, the present findings indicate that SDs induced oxidative stress in the liver of Wistar rats and for the first time, to the best of our knowledge, indicate that SDC disrupts hepatic CYP enzymes that may affect drug metabolism. Therefore, drug-dosing programs should be carefully designed to take these novel findings into consideration for the treatment of diseases.

  16. An automated, high-throughput, 384 well Cytochrome P450 cocktail IC50 assay using a rapid resolution LC-MS/MS end-point.

    Science.gov (United States)

    Youdim, Kuresh A; Lyons, Richard; Payne, Leon; Jones, Barry C; Saunders, Kenneth

    2008-09-10

    The current study focused on the development of an automated IC50 cocktail assay in a miniaturized 384 well assay format. This was developed in combination with a significantly shorter high pressure liquid chromatography (HPLC) separation and liquid chromatography-mass spectrometry (LC-MS/MS) run-time; than those currently reported in the literature. The 384-well assay used human liver microsomes in conjunction with a cocktail of probe substrates metabolized by the five major CYPs (tacrine for CYP1A2, diclofenac for CYP2C9, (S)-mephenytoin for CYP2C19, dextromethorphan for CYP2D6 and midazolam for CYP3A4). To validate the usefulness of the automated and analytical methodologies, IC50 determinations were performed for a series of test compounds known to exhibit inhibition across these five major P450s. Eight compounds (sertraline, disulfuram, ticlopidine fluconazole, fluvoxamine, ketoconazole, miconazole, paroxetine, flunitrazepam) were studied as part of a cocktail assay, and against each CYPs individually. The data showed that the IC50s generated with cocktail incubations did not differ to a great extent from those obtained in the single probe experiments and hence unlikely to significantly influence the predicted clinical DDI risk. In addition the present method offered a significant advantage over some of the existing cocktail analytical methodology in that separation can be achieved with run times as short as 1 min without compromising data integrity. Although numerous studies have been reported to measure CYP inhibition in a cocktail format the need to support growing discovery libraries not only relies on higher throughput assays but quicker analytical run times. The current study reports a miniaturized high-throughput cocktail IC50 assay, in conjunction with a robust, rapid resolution LC-MS/MS end-point offered increased sample throughput without compromising analytical sensitivity or analyte resolution.

  17. Dose-response of Berberine on Hepatic Cytochromes P450 mRNA Expression and Activities in Mice

    Science.gov (United States)

    Guo, Ying; Pope, Chad; Cheng, Xingguo; Zhou, Honghao; Klaassen, Curtis D.

    2011-01-01

    Ethnopharmacological relevance Berberine is an isoquinoline alkaloid isolated from the root and bark of plants such as goldenseal, Berberis, and Chinese goldthread. Berberine-containing crude drugs have been used as an antimicrobial remedy against gastrointestinal infections for thousands of years. It is also widely used in Asian countries for diabetes, hypertension, and hypercholesterolemia therapy. Aim of the Study Potential drug-drug interactions are of concern because of the wide usage of berberine. A few studies have reported interactions between berberine and cytochromes P450 (CYPs) in vitro, but little is known about whether berberine influences CYPs in vivo, especially after repeated administration. In this study, eight-week-old male C57BL/6 mice were given berberine orally (0,10, 30, 100, 300 mg/kg, i.g., daily for 14 days), and the effect of berberine on over 20 major Cyps and related nuclear receptors in mice livers were examined at both the mRNA and enzyme activity levels. Results In general, liver function of mice treated with various doses of berberine had no significant change, and repeated oral administration of the 3 lower doses of berberine for 14 days did not affect the expression of genes examined. However, after the highest dose of berberine (300 mg/kg), Cyp3a11 and Cyp3a25 mRNA decreased 67.6 and 87.4%, respectively, whereas Cyp1a2 mRNA increased 43.2%, and enzyme activities of Cyp3a11 and Cyp2d22 decreased 67.9 and 32.4%, respectively. Cyp2a4, 2b10 and Cyp2c29 were not altered at both mRNA and enzyme activity levels. Conclusions If studies in mice extrapolate to humans, lower doses of berberine appear to present a low risk of producing drug-drug interactions as a result of changed Cyp enzyme activity. However, high doses of berberine may suppress Cyp activities and result in drug-drug interactions. PMID:21920422

  18. Structural Diversity of Eukaryotic Membrane Cytochrome P450s*

    OpenAIRE

    Johnson, Eric F.; Stout, C. David

    2013-01-01

    X-ray crystal structures are available for 29 eukaryotic microsomal, chloroplast, or mitochondrial cytochrome P450s, including two non-monooxygenase P450s. These structures provide a basis for understanding structure-function relations that underlie their distinct catalytic activities. Moreover, structural plasticity has been characterized for individual P450s that aids in understanding substrate binding in P450s that mediate drug clearance.

  19. CYP-specific bioactivation of four organophosphorothioate pesticides by human liver microsomes.

    Science.gov (United States)

    Buratti, Franca M; Volpe, Maria Teresa; Meneguz, Annarita; Vittozzi, Luciano; Testai, Emanuela

    2003-02-01

    The bioactivation of azinphos-methyl (AZIN), chlorpyrifos (CPF), diazinon (DIA), and parathion (PAR), four widely used organophosphorothioate (OPT) pesticides has been investigated in human liver microsomes (HLM). In addition, the role of human cytochrome P450 (CYPs) in OPT desulfuration at pesticide levels representative of human exposure have been defined by means of correlation and immunoinhibition studies. CYP-mediated oxon formation from the four OPTs is efficiently catalyzed by HLM, although showing a high variability (>40-fold) among samples. Two distinct phases were involved in the desulfuration of AZIN, DIA, and PAR, characterized by different affinity constants (K(mapp1) = 0.13-9 microM and K(mapp2) = 5- 269 microM). Within the range of CPF concentrations tested, only the high-affinity component was evidenced (K(mapp1) = 0.27-0.94 microM). Oxon formation in phenotyped individual HLM showed a significant correlation with CYP1A2-, 3A4-, and 2B6-related activities, at different levels depending on the OPT concentration. Anti-human CYP1A2, 2B6, and 3A4 antibodies significantly inhibited oxon formation, showing the same OPT concentration dependence. Our data indicated that CYP1A2 is mainly involved in OPT desulfuration at low pesticide concentrations, while the role of CYP3A4 is more significant to the low-affinity component of OPT bioactivation. The contribution of CYP2B6 to total hepatic oxon formation was relevant in a wide range of pesticide concentrations, being a very efficient catalyst of both the high- and low-affinity phase. These results suggest CYP1A2 and 2B6 as possible metabolic biomarkers of susceptibility to OPT toxic effect at the actual human exposure levels.

  20. Synthetic Biology with Cytochromes P450 Using Photosynthetic Chassis

    DEFF Research Database (Denmark)

    Gnanasekaran, Thiyagarajan

    of these commercially important high value bioactive compounds are plant derived, and in plants, some of the key enzymes that catalyze the production of these compounds are cytochromes P450 (P450s). This thesis focuses on three subprojects in which we expressed plant metabolic pathways involving P450 enzymes...

  1. Effects of green tea catechins on cytochrome P450 2B6, 2C8, 2C19, 2D6 and 3A activities in human liver and intestinal microsomes.

    Science.gov (United States)

    Misaka, Shingen; Kawabe, Keisuke; Onoue, Satomi; Werba, José Pablo; Giroli, Monica; Tamaki, Sekihiro; Kan, Toshiyuki; Kimura, Junko; Watanabe, Hiroshi; Yamada, Shizuo

    2013-01-01

    The effects of green tea catechins on the main drug-metabolizing enzymatic system, cytochrome P450 (CYP), have not been fully elucidated. The objective of the present study was to evaluate the effects of green tea extract (GTE, total catechins 86.5%, w/w) and (-)-epigallocatechin-3-gallate (EGCG) on the activities of CYP2B6, CYP2C8, CYP2C19, CYP2D6 and CYP3A in vitro, using pooled human liver and intestinal microsomes. Bupropion hydroxylation, amodiaquine N-deethylation, (S)-mephenytoin 4'-hydroxylation, dextromethorphan O-demethylation and midazolam 1'-hydroxylation were assessed in the presence or absence of various concentrations of GTE and EGCG to test their effects on CYP2B6, CYP2C8, CYP2C19, CYP2D6 and CYP3A activities, respectively. Each metabolite was quantified using UPLC/ESI-MS, and the inhibition kinetics of GTE and EGCG on CYP enzymes was analyzed. In human liver microsomes, IC50 values of GTE were 5.9, 4.5, 48.7, 25.1 and 13.8 µg/mL, for CYP2B6, CYP2C8, CYP2C19, CYP2D6 and CYP3A, respectively. ECGC also inhibited these CYP isoforms with properties similar to those of GTE, and produced competitive inhibitions against CYP2B6 and CYP2C8, and noncompetitive inhibition against CYP3A. In human intestinal microsomes, IC50 values of GTE and EGCG for CYP3A were 18.4 µg/mL and 31.1 µM, respectively. EGCG moderately inhibited CYP3A activity in a noncompetitive manner. These results suggest that green tea catechins cause clinically relevant interactions with substrates for CYP2B6 and CYP2C8 in addition to CYP3A.

  2. Identification of metabolic pathways involved in the biotransformation of tolperisone by human microsomal enzymes.

    Science.gov (United States)

    Dalmadi, Balázs; Leibinger, János; Szeberényi, Szabolcs; Borbás, Tímea; Farkas, Sándor; Szombathelyi, Zsolt; Tihanyi, Károly

    2003-05-01

    The in vitro metabolism of tolperisone, 1-(4-methyl-phenyl)-2-methyl-3-(1-piperidino)-1-propanone-hydrochloride, a centrally acting muscle relaxant, was examined in human liver microsomes (HLM) and recombinant enzymes. Liquid chromatography-mass spectrometry measurements revealed methyl-hydroxylation (metabolite at m/z 261; M1) as the main metabolic route in HLM, however, metabolites of two mass units greater than the parent compound and the hydroxy-metabolite were also detected (m/z 247 and m/z 263, respectively). The latter was identified as carbonyl-reduced M1, the former was assumed to be the carbonyl-reduced parent compound. Isoform-specific cytochrome P450 (P450) inhibitors, inhibitory antibodies, and experiments with recombinant P450s pointed to CYP2D6 as the prominent enzyme in tolperisone metabolism. CYP2C19, CYP2B6, and CYP1A2 are also involved to a smaller extent. Hydroxymethyl-tolperisone formation was mediated by CYP2D6, CYP2C19, CYP1A2, but not by CYP2B6. Tolperisone competitively inhibited dextromethorphan O-demethylation and bufuralol hydroxylation (K(i) = 17 and 30 microM, respectively). Tolperisone inhibited methyl p-tolyl sulfide oxidation (K(i) = 1200 microM) in recombinant flavin-containing monooxygenase 3 (FMO3) and resulted in a 3-fold (p tolperisone undergoes P450-dependent and P450-independent microsomal biotransformations to the same extent. On the basis of metabolites formed and indirect evidences of inhibition studies, a considerable involvement of a microsomal reductase is assumed.

  3. Hepatic CYP1A, 2B, 2C, 2E and 3A regulation by methoxychlor in male and female rats.

    Science.gov (United States)

    Oropeza-Hernández, Luis F; López-Romero, Ricardo; Albores, Arnulfo

    2003-09-15

    The effect on liver cytochrome P450 (CYP) by i.p. injections of methoxychlor (MXC) in corn oil at 0, 100, 150, 200 or 250 mg/kg twice daily for 3 days was investigated in adult male and female Wistar rats. The MXC injection (100 mg/kg b.w.) caused a similar increase of total CYP content in males and females as compared with controls who received the vehicle only. In males, this increase continued up to 250 mg/kg. As to the induction of specific CYP activities, the effect of MXC was found to be sex dependent with three different patterns. Males showed the greatest increases of ethoxy- and methoxyresorufin-O-dealkylase (EROD and MROD, respectively), two CYP1A1/1A2-related activities. On the contrary, females were more responsive