ChemInform Abstract: Enantioselective Intramolecular C-H Amination Catalyzed by Engineered Cytochrome P450 Enzymes in vitro and in vivo.

ChemInform ◽  
2014 ◽  
Vol 45 (3) ◽  
pp. no-no
Author(s):  
John A. McIntosh ◽  
Pedro S. Coelho ◽  
Christopher C. Farwell ◽  
Z. Jane Wang ◽  
Jared C. Lewis ◽  
...  
Keyword(s):  
Cytochrome P450 ◽  
Cytochrome P450 Enzymes

scholarly journals Enzymatic activity in turkey, duck, quail and chicken liver microsomes against four human cytochrome P450 prototype substrates and aflatoxin B1

2011 ◽  
Vol 1 (1) ◽  
pp. 4 ◽  
Author(s):  
Hansen W. Murcia ◽  
Gonzalo J. Díaz ◽  
Sandra Milena Cepeda
Keyword(s):  
Cytochrome P450 ◽  
Aflatoxin B1 ◽  
Enzyme Activities ◽  
High Performance ◽  
Biochemical Characterization ◽  
Liver Microsomes ◽  
Cytochrome P450 Enzymes ◽  
Catalytic Rate

Cytochrome P450 enzymes (CYP) are a group of monooxygenases able to biotransform several kinds of xenobiotics including aflatoxin B1 (AFB1), a highly toxic mycotoxin. These enzymes have been widely studied in humans and others mammals, but there is not enough information in commercial poultry species about their biochemical characteristics or substrate specificity. The aim of the present study was to identify CYPs from avian liver microsomes with the use of prototype substrates specific for human CYP enzymes and AFB1. Biochemical characterization was carried out in vitro and biotransformation products were detected by high-performance liquid chromatography (HPLC). Enzymatic constants were calculated and comparisons between turkey, duck, quail and chicken activities were done. The results demonstrate the presence of four avian ortholog enzyme activities possibly related with a CYP1A1, CYP1A2, CYP2A6 (activity not previously identified) and CYP3A4 poultry orthologs, respectively. Large differences in enzyme kinetics specific for prototype substrates were found among the poultry species studied. Turkey liver microsomes had the highest affinity and catalytic rate for AFB1 whereas chicken enzymes had the lowest affinity and catalytic rate for the same substrate. Quail and duck microsomes showed intermediate values. These results correlate well with the known in vivo sensitivity for AFB1 except for the duck. A high correlation coefficient between 7-ethoxyresorufin-Odeethylase (EROD) and 7-methoxyresorufin- O-deethylase (MROD) activities was found in the four poultry species, suggesting that these two enzymatic activities might be carried out by the same enzyme. The results of the present study indicate that four prototype enzyme activities are present in poultry liver microsomes, possibly related with the presence of three CYP avian orthologs. More studies are needed in order to further characterize these enzymes.

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

2017 ◽  
Vol 9 (7) ◽  
pp. 163-177
Author(s):  
Dominik Dahlinger ◽  
Sevinc Aslan ◽  
Markus Pietsch ◽  
Sebastian Frechen ◽  
Uwe Fuhr
Keyword(s):  
Cytochrome P450 ◽  
Liver Microsomes ◽  
Fold Increase ◽  
Pharmacokinetic Data ◽  
Cytochrome P450 Enzymes ◽  
Trospium Chloride ◽  
Screening Experiments ◽  
Human Cytochrome

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 to potentially inhibit CYP2D6 at clinically occurring concentrations.

scholarly journals Prediction of cytochrome P450-mediated drug clearance in humans based on the measured activities of selected CYPs

2017 ◽  
Vol 37 (6) ◽  
Author(s):  
Jie Gao ◽  
Jie Wang ◽  
Na Gao ◽  
Xin Tian ◽  
Jun Zhou ◽  
...  
Keyword(s):  
Cytochrome P450 ◽  
Liver Microsomes ◽  
Normal Liver ◽  
Drug Clearance ◽  
Cytochrome P450 Enzymes ◽  
Simple Method ◽  
Drug Metabolizing Enzyme ◽  
Descriptive Models

Determining drug-metabolizing enzyme activities on an individual basis is an important component of personalized medicine, and cytochrome P450 enzymes (CYPs) play a principal role in hepatic drug metabolism. Herein, a simple method for predicting the major CYP-mediated drug clearance in vitro and in vivo is presented. Ten CYP-mediated drug metabolic activities in human liver microsomes (HLMs) from 105 normal liver samples were determined. The descriptive models for predicting the activities of these CYPs in HLMs were developed solely on the basis of the measured activities of a smaller number of more readily assayed CYPs. The descriptive models then were combined with the Conventional Bias Corrected in vitro–in vivo extrapolation method to extrapolate drug clearance in vivo. The Vmax, Km, and CLint of six CYPs (CYP2A6, 2C8, 2D6, 2E1, and 3A4/5) could be predicted by measuring the activities of four CYPs (CYP1A2, 2B6, 2C9, and 2C19) in HLMs. Based on the predicted CLint, the values of CYP2A6-, 2C8-, 2D6-, 2E1-, and 3A4/5-mediated drug clearance in vivo were extrapolated and found that the values for all five drugs were close to the observed clearance in vivo. The percentage of extrapolated values of clearance in vivo which fell within 2-fold of the observed clearance ranged from 75.2% to 98.1%. These findings suggest that measuring the activity of CYP1A2, 2B6, 2C9, and 2C19 allowed us to accurately predict CYP2A6-, 2C8-, 2D6-, 2E1-, and 3A4/5-mediated activities in vitro and in vivo and may possibly be helpful for the assessment of an individual’s drug metabolic profile.

scholarly journals Effects of Ospemifene on Drug Metabolism Mediated by Cytochrome P450 Enzymes in Humans in Vitro and in Vivo

2013 ◽  
Vol 14 (7) ◽  
pp. 14064-14075 ◽  
Author(s):  
Miia Turpeinen ◽  
Jouko Uusitalo ◽  
Terhi Lehtinen ◽  
Marita Kailajärvi ◽  
Olavi Pelkonen ◽  
...  
Keyword(s):  
Cytochrome P450 ◽  
Drug Metabolism ◽  
Cytochrome P450 Enzymes

Interactions of the hepatitis C virus protease inhibitor faldaprevir with cytochrome P450 enzymes: In vitro and in vivo correlation

2015 ◽  
Vol 55 (4) ◽  
pp. 467-477 ◽  
Author(s):  
John P. Sabo ◽  
Jens Kort ◽  
Charles Ballow ◽  
Angela D.M. Kashuba ◽  
Manuel Haschke ◽  
...  
Keyword(s):  
Cytochrome P450 ◽  
Hepatitis C Virus ◽  
Hepatitis C ◽  
Protease Inhibitor ◽  
Cytochrome P450 Enzymes

scholarly journals Inhibition and Induction by Poziotinib of Different Rat Cytochrome P450 Enzymes In Vivo and in an In Vitro Cocktail Method

2021 ◽  
Vol 11 ◽  
Author(s):  
Jinhui Wang ◽  
Feifei Chen ◽  
Hui Jiang ◽  
Jia Xu ◽  
Deru Meng ◽  
...  
Keyword(s):  
Cytochrome P450 ◽  
Rat Liver ◽  
Clinical Investigation ◽  
Liver Microsomes ◽  
Pharmacokinetic Parameters ◽  
Rat Liver Microsomes ◽  
Cytochrome P450 Enzymes ◽  
Significant Difference

Poziotinib is an orally active, irreversible, pan-HER tyrosine kinase inhibitor used to treat non-small cell lung cancer, breast cancer, and gastric cancer. Poziotinib is currently under clinical investigation, and understanding its drug-drug interactions is extremely important for its future development and clinical application. The cocktail method is most suitable for evaluating the activity of cytochrome P450 enzymes (CYPs). As poziotinib is partially metabolized by CYPs, cocktail probes are used to study the interaction between drugs metabolized by each CYP subtype. Midazolam, bupropion, dextromethorphan, tolbutamide, chlorzoxazone, phenacetin, and their metabolites were used to examine the effects of poziotinib on the activity of cyp1a2, 2b1, 2d1, 2c11, 2e1, and 3a1/2, respectively. The in vitro experiment was carried out by using rat liver microsomes (RLMs), whereas the in vivo experiment involved the comparison of the pharmacokinetic parameters of the probes after co-administration with poziotinib to rats to those of control rats treated with only probes. UPLC-MS/MS was used to detect the probes and their metabolites in rat plasma and rat liver microsomes. The in vitro results revealed that the half-maximal inhibitory concentration values of bupropion and tolbutamide in RLMs were 8.79 and 20.17 μM, respectively, indicating that poziotinib showed varying degrees of inhibition toward cyp2b1 and cyp2c11. Poziotinib was a competitive inhibitor of cyp2b1 and cyp2c11, with Ki values of 16.18 and 17.66 μM, respectively. No time- or concentration-dependence of inhibition by poziotinib was observed toward cyp2b1 and cyp2c11 in RLMs. Additionally, no obvious inhibitory effects were observed on the activity of cyp1a2, cyp2d1, cyp2e1, and cyp3a1/2. In vivo analysis revealed that bupropion, tolbutamide, phenacetin, and chlorzoxazone showed significantly different pharmacokinetic parameters after administration (p < 0.05); there was no significant difference in the pharmacokinetic parameters of dextromethorphan and midazolam. These results show that poziotinib inhibited cyp2b1 and cyp2c11, but induced cyp1a2 and cyp2e1 in rats. Thus, poziotinib inhibited cyp2b1 and cyp2c11 activity in rats, suggesting the possibility of interactions between poziotinib and these CYP substrates and the need for caution when combining them in clinical settings.

In Vivo and in Vitro Induction of Cytochrome P450 Enzymes in Beagle Dogs

2002 ◽  
Vol 30 (11) ◽  
pp. 1206-1213 ◽  
Author(s):  
Richard A. Graham ◽  
April Downey ◽  
Dan Mudra ◽  
Linda Krueger ◽  
Kathy Carroll ◽  
...  
Keyword(s):  
Cytochrome P450 ◽  
Beagle Dogs ◽  
Cytochrome P450 Enzymes ◽  
In Vitro Induction

scholarly journals Effect of Endocannabinoid Oleamide on Rat and Human Liver Cytochrome P450 Enzymes in In Vitro and In Vivo Models

2018 ◽  
Vol 46 (6) ◽  
pp. 913-923 ◽  
Author(s):  
Gabriela Dovrtelova ◽  
Ondrej Zendulka ◽  
Kristyna Noskova ◽  
Jan Jurica ◽  
Ondrej Pes ◽  
...  
Keyword(s):  
Cytochrome P450 ◽  
Human Liver ◽  
Cytochrome P450 Enzymes ◽  
In Vivo Models ◽  
Liver Cytochrome

scholarly journals Enantioselective Intramolecular CH Amination Catalyzed by Engineered Cytochrome P450 Enzymes In Vitro and In Vivo

2013 ◽  
Vol 52 (35) ◽  
pp. 9309-9312 ◽  
Author(s):  
John A. McIntosh ◽  
Pedro S. Coelho ◽  
Christopher C. Farwell ◽  
Z. Jane Wang ◽  
Jared C. Lewis ◽  
...  
Keyword(s):  
Cytochrome P450 ◽  
Cytochrome P450 Enzymes
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