Occurrence of the NIH Shift upon the Cytochrome P450-Catalyzed in Vivo and in Vitro Aromatic Ring Hydroxylation of Fluorobenzenes

1998 ◽  
Vol 11 (5) ◽  
pp. 503-512 ◽  
Author(s):  
Janneke Koerts ◽  
Ans E. M. F. Soffers ◽  
Jacques Vervoort ◽  
Adrie De Jager ◽  
Ivonne M. C. M. Rietjens
Keyword(s):  
Cytochrome P450 ◽  
Aromatic Ring ◽  
Ring Hydroxylation

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.

Nitric Oxide Mediates Hepatic Cytochrome P450 Dysfunction Induced by Endotoxin

1996 ◽  
Vol 84 (6) ◽  
pp. 1435-1442 ◽  
Author(s):  
Claudia M. Muller ◽  
Annette Scierka ◽  
Richard L. Stiller ◽  
Yong-Myeong Kim ◽  
Ryan D. Cook ◽  
...  
Keyword(s):  
Nitric Oxide ◽  
Cytochrome P450 ◽  
Drug Metabolism ◽  
Sprague Dawley ◽  
Cytochrome P450 Content ◽  
Nitrate Concentrations ◽  
Hypnotic Drugs ◽  
Plasma Nitrite

Background Animals subjected to immunostimulatory conditions (sepsis) exhibit decreased total cytochrome P450 content and decreased P450-dependent drug metabolism. Cytochrome P450 function is of clinical significance because it mediates the metabolism of some opioid and hypnotic drugs. The authors tested the hypothesis that reduced P450 function and decreased drug metabolism in sepsis are mediated by endotoxin-enhanced synthesis of nitric oxide. Methods Hepatic microsomes were prepared from male Sprague-Dawley rats in nontreated rats, rats pretreated with phenobarbital and rats receiving aminoguanidine or NG-L-monomethyl-arginine alone. Nitric oxide synthesis was augmented for 12 h with a single injection of bacterial lipopolysaccharides. Nitric oxide synthase was inhibited with aminoguanidine or N(G)-L-monomethyl-arginine during the 12 h of endotoxemia in some animals. Plasma nitrite and nitrate concentrations were measured in vivo, and total microsomal P450 content, and metabolism of ethylmorphine and midazolam in vitro. Results Administration of endotoxin increased plasma nitrite and nitrate concentrations, decreased total cytochrome P450 content, and decreased metabolism of ethylmorphine and midazolam. Inhibition of nitric oxide formation by aminoguanidine or N(G)-L-monomethyl-arginine partially prevented the endotoxin-induced effects in the nontreated and phenobarbital-treated groups. Aminoguanidine or N(G)-L-monomethyl-arginine alone did not have an effect on either total cytochrome P450 content or P450-dependent drug metabolism. Plasma nitrite and nitrate concentrations correlated significantly negatively with P450 content (nontreated r = -0.88, phenobarbital r = -0.91), concentrations of formed formaldehyde (nontreated r = -0.87, phenobarbital r = -0.95), and concentrations of midazolam metabolites (4-OH midazolam nontreated r = -0.88, phenobarbital r = -0.93, and 1'-OH midazolam nontreated r = -0.88, phenobarbital r = -0.97). Conclusions Altered hepatic microsomal ethylmorphine and midazolam metabolism during sepsis is mediated in large part by nitric oxide.

scholarly journals Which cytochrome P450 metabolizes phenazepam? Step by step in silico, in vitro, and in vivo studies

2018 ◽  
Vol 33 (2) ◽  
pp. 65-73 ◽  
Author(s):  
Dmitriy V. Ivashchenko ◽  
Anastasia V. Rudik ◽  
Andrey A. Poloznikov ◽  
Sergey V. Nikulin ◽  
Valeriy V. Smirnov ◽  
...  
Keyword(s):  
Cell Culture ◽  
Cytochrome P450 ◽  
In Silico ◽  
In Vivo Studies ◽  
Cyp3a Activity ◽  
Cell Culture Study ◽  
Study Results ◽  
Three Stages

Abstract Background: Phenazepam (bromdihydrochlorphenylbenzodiazepine) is the original Russian benzodiazepine tranquilizer belonging to 1,4-benzodiazepines. There is still limited knowledge about phenazepam’s metabolic liver pathways and other pharmacokinetic features. Methods: To determine phenazepam’s metabolic pathways, the study was divided into three stages: in silico modeling, in vitro experiment (cell culture study), and in vivo confirmation. In silico modeling was performed on the specialized software PASS and GUSAR to evaluate phenazepam molecule affinity to different cytochromes. The in vitro study was performed using a hepatocytes’ cell culture, cultivated in a microbioreactor to produce cytochrome P450 isoenzymes. The culture medium contained specific cytochrome P450 isoforms inhibitors and substrates (for CYP2C9, CYP3A4, CYP2C19, and CYP2B6) to determine the cytochrome that was responsible for phenazepam’s metabolism. We also measured CYP3A activity using the 6-betahydroxycortisol/cortisol ratio in patients. Results: According to in silico and in vitro analysis results, the most probable metabolizer of phenazepam is CYP3A4. By the in vivo study results, CYP3A activity decreased sufficiently (from 3.8 [95% CI: 2.94–4.65] to 2.79 [95% CI: 2.02–3.55], p=0.017) between the start and finish of treatment in patients who were prescribed just phenazepam. Conclusions: Experimental in silico and in vivo studies confirmed that the original Russian benzodiazepine phenazepam was the substrate of CYP3A4 isoenzyme.

In vitro inhibitory effects of glucosamine, chondroitin and diacerein on human hepatic CYP2D6

2021 ◽  
Vol 36 (4) ◽  
pp. 259-270
Author(s):  
Boon Hooi Tan ◽  
Nafees Ahemad ◽  
Yan Pan ◽  
Uma Devi Palanisamy ◽  
Iekhsan Othman ◽  
...  
Keyword(s):  
Cytochrome P450 ◽  
High Performance ◽  
Inhibitory Effect ◽  
Inhibitory Effects ◽  
Time Curve ◽  
Clinical Drugs ◽  
Inhibition Potencies ◽  
P450 2D6

Abstract Objectives Glucosamine, chondroitin and diacerein are natural compounds commonly used in treating osteoarthritis. Their concomitant intake may trigger drug–natural product interactions. Cytochrome P450 (CYP) has been implicated in such interactions. Cytochrome P450 2D6 (CYP2D6) is a major hepatic CYP involved in metabolism of 25% of the clinical drugs. This study aimed to investigate the inhibitory effect of these antiarthritic compounds on CYP2D6. Methods CYP2D6 was heterologously expressed in Escherichia coli. CYP2D6–antiarthritic compound interactions were studied using in vitro enzyme kinetics assay and molecular docking. Results The high-performance liquid chromatography (HPLC)-based dextromethorphan O-demethylase assay was established as CYP2D6 marker. All glucosamines and chondroitins weakly inhibited CYP2D6 (IC50 values >300 µM). Diacerein exhibited moderate inhibition with IC50 and K i values of 34.99 and 38.27 µM, respectively. Its major metabolite, rhein displayed stronger inhibition potencies (IC50=26.22 μM and K i =32.27 μM). Both compounds exhibited mixed-mode of inhibition. In silico molecular dockings further supported data from the in vitro study. From in vitro–in vivo extrapolation, rhein presented an area under the plasma concentration-time curve (AUC) ratio of 1.5, indicating low potential to cause in vivo inhibition. Conclusions Glucosamine, chondroitin and diacerein unlikely cause clinical interaction with the drug substrates of CYP2D6. Rhein, exhibits only low potential to cause in vivo inhibition.

scholarly journals Evaluation of acacetin inhibition potential against cytochrome P450 in vitro and in vivo

2020 ◽  
Vol 329 ◽  
pp. 109147 ◽  
Author(s):  
Yunfang Zhou ◽  
Yingying Tu ◽  
Quan Zhou ◽  
Ailian Hua ◽  
Peiwu Geng ◽  
...  
Keyword(s):  
Cytochrome P450

scholarly journals Phenobarbital influence on neuromuscular block produced by rocuronium in rats

2008 ◽  
Vol 23 (4) ◽  
pp. 343-347 ◽  
Author(s):  
Angélica de Fátima de Assunção Braga ◽  
Caroline Coutinho de Barcelos ◽  
Franklin Sarmento da Silva Braga ◽  
Samanta Cristina Antoniassi Fernandes ◽  
Yoko Oshima Franco ◽  
...  
Keyword(s):  
Cytochrome P450 ◽  
Neuromuscular Blockade ◽  
Neuromuscular Block ◽  
Cytochrome B5 ◽  
Muscle Response ◽  
In Vivo Experiments ◽  
Hepatic Microsomes ◽  
Enzymatic Induction

PURPOSE: To evaluate in vitro and in vivo neuromuscular blockade produced by rocuronium in rats treated with Phenobarbital and to determine cytochrome P450 and cytochrome b5 concentrations in hepatic microsomes. METHODS: Thirty rats were included in the study and distributed into 6 groups of 5 animals each. Rats were treated for seven days with phenobarbital (20 mg/kg) and the following parameters were evaluated: 1) the amplitude of muscle response in the preparation of rats exposed to phenobarbital; 2) rocuronium effect on rat preparation exposed or not to phenobarbital; 3) concentrations of cytochrome P450 and cytochrome b5 in hepatic microsomes isolated from rats exposed or not to phenobarbital. The concentration and dose of rocuronium used in vitro and in vivo experiments were 4 µg/mL and 0,6 mg/kg, respectively. RESULTS: Phenobarbital in vitro and in vivo did not alter the amplitude of muscle response. The neuromuscular blockade in vitro produced by rocuronium was significantly different (p=0.019) between exposed (20%) and not exposed (60%) rats; the blockade in vivo was significantly greater (p=0.0081) in treated rats (93.4%). The enzymatic concentrations were significantly greater in rats exposed to phenobarbital. CONCLUSIONS: Phenobarbital alone did not compromise neuromuscular transmission. It produced enzymatic induction, and neuromuscular blockade in vivo produced by rocuronium was potentiated by phenobarbital.

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