scholarly journals Inhibition of Cytochrome P450 (CYP450) Isoforms by Isoniazid: Potent Inhibition of CYP2C19 and CYP3A

2001 ◽  
Vol 45 (2) ◽  
pp. 382-392 ◽  
Author(s):  
Zeruesenay Desta ◽  
Nadia V. Soukhova ◽  
David A. Flockhart
Keyword(s):  
Cytochrome P450 ◽  
Liver Microsomes ◽  
Cost Effective ◽  
Competitive Inhibitor ◽  
Inhibitory Effect ◽  
Significant Inhibition ◽  
Specific Substrate ◽  
Dependent Manner ◽  
Concentration Dependent Manner ◽  
The Mean

ABSTRACT Isoniazid (INH) remains the most safe and cost-effective drug for the treatment and prophylaxis of tuberculosis. The use of INH has increased over the past years, largely as a result of the coepidemic of human immunodeficiency virus infection. It is frequently given chronically to critically ill patients who are coprescribed multiple medications. The ability of INH to elevate the concentrations in plasma and/or toxicity of coadministered drugs, including those of narrow therapeutic range (e.g., phenytoin), has been documented in humans, but the mechanisms involved are not well understood. Using human liver microsomes (HLMs), we tested the inhibitory effect of INH on the activity of common drug-metabolizing human cytochrome P450 (CYP450) isoforms using isoform-specific substrate probe reactions. Incubation experiments were performed at a single concentration of each substrate probe at its Km value with a range of INH concentrations. CYP2C19 and CYP3A were inhibited potently by INH in a concentration-dependent manner. At 50 μM INH (∼6.86 μg/ml), the activities of these isoforms decreased by ∼40%. INH did not show significant inhibition (<10% at 50 μM) of other isoforms (CYP2C9, CYP1A2, and CYP2D6). To accurately estimate the inhibition constants (Ki values) for each isoform, four concentrations of INH were incubated across a range of five concentrations of specific substrate probes. The meanKi values (± standard deviation) for the inhibition of CYP2C19 by INH in HLMs and recombinant human CYP2C19 were 25.4 ± 6.2 and 13 ± 2.4 μM, respectively. INH showed potent noncompetitive inhibition of CYP3A (Ki = 51.8 ± 2.5 to 75.9 ± 7.8 μM, depending on the substrate used). INH was a weak noncompetitive inhibitor of CYP2E1 (Ki = 110 ± 33 μM) and a competitive inhibitor of CYP2D6 (Ki = 126 ± 23 μM), but the mean Ki values for the inhibition of CYP2C9 and CYP1A2 were above 500 μM. Inhibition of one or both CYP2C19 and CYP3A isoforms is the likely mechanism by which INH slows the elimination of coadministered drugs, including phenytoin, carbamazepine, diazepam, triazolam, and primidone. Slow acetylators of INH may be at greater risk for adverse drug interactions, as the degree of inhibition was concentration dependent. These data provide a rational basis for understanding drug interaction with INH and predict that other drugs metabolized by these two enzymes may also interact.

scholarly journals In vitro study on the effect of cornin on the activity of cytochrome P450 enzymes

2021 ◽  
Vol 21 (1) ◽  
Author(s):  
Qun Zhang ◽  
Zengqiang Qu ◽  
Yanqing Zhou ◽  
Jin Zhou ◽  
Junwei Yang ◽  
...  
Keyword(s):  
Cytochrome P450 ◽  
Drug Interaction ◽  
Liver Microsomes ◽  
In Vitro Study ◽  
Inhibitory Effect ◽  
Dependent Manner ◽  
Cytochrome P450 Enzymes ◽  
Drug Drug Interaction ◽  
Dose Dependent

Abstract Background Cornin is a commonly used herb in cardiology for its cardioprotective effect. The effect of herbs on the activity of cytochrome P450 enzymes (CYP450s) can induce adverse drug-drug interaction even treatment failure. Therefore, it is necessary to investigate the effect of cornin on the activity of CYP450s, which can provide more guidance for the clinical application of cornin. Methods Cornin (100 μM) was incubated with eight isoforms of CYP450s, including CYP1A2, 2A6, 3A4, 2C8, 2C9, 2C19, 2D6, and 2E1, in pooled human liver microsomes. The inhibition model and corresponding parameters were also investigated. Results Cornin exerted significant inhibitory effect on the activity of CYP3A4, 2C9, and 2E1 in a dose-dependent manner with the IC50 values of 9.20, 22.91, and 14.28 μM, respectively (p < 0.05). Cornin inhibited the activity of CYP3A4 non-competitively with the Ki value of 4.69 μM, while the inhibition of CYP2C9 and 2E1 by cornin was competitive with the Ki value of 11.31 and 6.54 μM, respectively. Additionally, the inhibition of CYP3A4 by cornin was found to be time-dependent with the KI/Kinact value of 6.40/0.055 min− 1·μM− 1. Conclusions The inhibitory effect of cornin on the activity of CYP3A4, 2C9, and 2E1 indicated the potential drug-drug interaction between cornin and drugs metabolized by these CYP450s, which needs further investigation and validation.

The Inhibitory Effect of Herbal Medicine -Dai Kenchu To (DKT)- on the Colonic Motility in Rats In Vitro

2001 ◽  
Vol 29 (01) ◽  
pp. 111-118 ◽  
Author(s):  
Mohammad Alhakam Tulimat ◽  
Tadashi Ishiguchi ◽  
Susumu Kurosawa ◽  
Takashi Nakamura ◽  
Toku Takahashi
Keyword(s):  
Herbal Medicine ◽  
Colonic Motility ◽  
Distal Colon ◽  
Inhibitory Effect ◽  
Significant Inhibition ◽  
Ginseng Root ◽  
Dependent Manner ◽  
Concentration Dependent Manner ◽  
Beneficial Effects

Dai-Kenchu-To (DKT) is a herbal medicine and is currently used as the treatment of paralytic ileus in Japan. We investigated the mechanism of beneficial effects of DKT in vitro. DKT-extract powder (DKT-EP; 30–300 μg/ml) caused a significant inhibition on carbachol (CCH; 10-6)-induced contraction in a concentration dependent manner of the rat distal colon. DKT-EP (100 μg/ml) consists of 20 μg/ml of Zanthoxylum Fruit, 30 μg/ml of Ginseng Root and 50 μg/ml of Ginger Rhizome. Although each of them had no effect on CCH-induced muscle contraction, the combination of three ingredients caused a significant inhibition on CCH-induced contraction.

A study of the in vitro clinical interaction between lidocaine and premedications using rat liver microsomes

2002 ◽  
Vol 21 (8) ◽  
pp. 453-456 ◽  
Author(s):  
A Nagashima ◽  
E Tanaka ◽  
S Inomata ◽  
S Misawa
Keyword(s):  
Liver Microsomes ◽  
Competitive Inhibitor ◽  
Rat Liver Microsomes ◽  
Dependent Manner ◽  
Potential Importance ◽  
Concentration Dependent Manner ◽  
Hepatic Microsomes ◽  
The Relationship ◽  
Substrate Concentrations

In this study, we have investigated the relationship between lidocaine metabolism and premedication, i.e., psychotropic and anti-anxiety agents (diazepam, midazolam), hypnotics (pentobarbital, thiamylal), depolarizing muscular relaxants (vecuronium, pancuronium and suxamethonium), an active anti-hypertensive (clonidine) and an H2 receptor antagonist (cimetidine) using rat hepatic microsomes in vitro. Lidocaine metabolism was noncompetitively inhibited by midazolam (Ki=29.0 mM). Thilamylal was a moderate competitive inhibitor of lidocaine metabolism (Ki=77.8 mM). Pentobarbital, diazepam and cimetidine weakly inhibited lidocaine metabolism formation in a concentration-dependent manner at high substrate concentrations. On the other hand, vecuronium, pancuronium, suxamethonium and clonidine did not inhibit lidocaine metabolism over the therapeutic range. These results show that the interaction between lidocaine and midazolam and thiamylal, catalyzed by a similar cytochrome P450, is of potential importance in toxicological and clinical studies.

Inhibitory Effects of Garcinia cambogia Extract on CYP2B6 Enzyme Activity

Planta Medica ◽  
2017 ◽  
Vol 83 (11) ◽  
pp. 895-900 ◽  
Author(s):  
Jun Yu ◽  
Min Choi ◽  
Jong Park ◽  
Shaheed Rehman ◽  
Katsunori Nakamura ◽  
...  
Keyword(s):  
Cytochrome P450 ◽  
Enzyme Activities ◽  
Liver Microsomes ◽  
Cytochrome P450 Enzyme ◽  
Dependent Manner ◽  
Cytochrome P450 Enzymes ◽  
Inhibitory Effects ◽  
Concentration Dependent Manner ◽  
Garcinia Cambogia ◽  
P450 Enzyme

AbstractThis study assessed the inhibitory effects of Garcinia cambogia extract on the cytochrome P450 enzymes in vitro. G. cambogia extract was incubated with cytochrome P450 isozyme-specific substrates in human liver microsomes and recombinant CYP2B6 isozyme, and the formation of the marker metabolites was measured to investigate the inhibitory potential on cytochrome P450 enzyme activities. The results showed that G. cambogia extract has significant inhibitory effects on CYP2B6 activity in a concentration-dependent manner. Furthermore, the inhibition was potentiated following preincubation with NADPH, indicating that G. cambogia extract is a time-dependent inhibitor of CYP2B6. Meanwhile, hydroxycitric acid, the major bioactive ingredient of G. cambogia extract, did not exhibit significant inhibition effects on cytochrome P450 enzyme activities. G. cambogia extract could modulate the pharmacokinetics of CYP2B6 substrate drugs and lead to interactions with those drugs. Therefore, caution may be required with respect to concomitant intake of dietary supplements containing G. cambogia extract with CYP2B6 substrates.

Inhalation Anesthetics Inhibit the Release of Endothelium-derived Hyperpolarizing Factor in the Rabbit Carotid Artery

1995 ◽  
Vol 83 (3) ◽  
pp. 574-582. ◽  
Author(s):  
Volker Lischke ◽  
Rudi Busse ◽  
Markus Hecker
Keyword(s):  
Nitric Oxide ◽  
Cytochrome P450 ◽  
Carotid Artery ◽  
Sodium Nitroprusside ◽  
Liver Microsomes ◽  
Inhibitory Effect ◽  
Dependent Manner ◽  
Inhalation Anesthetics ◽  
Rabbit Carotid Artery ◽  
Relaxant Response

Background Inhalation anesthetics may interfere with the synthesis or action of endothelium-derived vasoactive factors. We investigated the effects of desflurane, enflurane, halothane, isoflurane, and sevoflurane on the release of nitric oxide and endothelium-derived hyperpolarizing factor (EDHF) in the isolated endothelium-intact carotid artery of the rabbit. Methods Isolated segments of the carotid artery were suspended in Krebs-Henseleit solution (37 degrees C) and preconstricted with phenylephrine (1 microM). Relaxations caused by acetylcholine (ACh) (0.03-10 microM) or sodium nitroprusside (0.01-10 microM) were compared in the presence or absence of the nitric oxide synthase inhibitor NG-nitro-L-arginine (0.1 mM) in segments exposed to desflurane (8%), enflurane (2-4%), halothane (2-3.5%), isoflurane (2-4%), or sevoflurane (2%) as well as in NG-nitro-L- arginine-treated segments exposed to enflurane (2%) in combination with the KCa(+)-channel blocker tetrabutylammonium (0.3 mM) or the cytochrome P450 inhibitor clotrimazole (3 microM). Results Desflurane, enflurane, and sevoflurane selectively inhibited the ACh-induced release of EDHF. Halothane and isoflurane also weakly affected the nitric oxide-mediated relaxant response to ACh. The inhibitory effect of these two anesthetics on EDHF release was concentration-dependent. Relaxations induced by sodium nitroprusside were not inhibited by any of the anesthetics tested. Three structurally unrelated cytochrome P450 inhibitors clotrimazole (0.1 mM), metyrapone (1 mM), and SKF525a (proadifen, 0.1 mM) abolished the EDHF-mediated relaxation elicited by ACh. The pharmacologic profile of the inhibitory effect of enflurane on the release of EDHF closely resembled that of clotrimazole but not that of tetrabutylammonium. Moreover, all anesthetics inhibited the cytochrome P450-catalyzed O-dealkylation of 7-ethoxycoumarin by rabbit liver microsomes in a concentration-dependent manner. Conclusions Inhalation anesthetics significantly attenuate the EDHF-mediated relaxant response to ACh in the rabbit carotid artery. This effect appears to be attributable to inhibition of the cytochrome P450-dependent synthesis of EDHF by the endothelium.

In Vitro and In Vivo Metabolic Activation of Obacunone, A Bioactive and Potentially Hepatotoxic Constituent of Dictamni Cortex

Planta Medica ◽  
2020 ◽  
Vol 86 (10) ◽  
pp. 686-695 ◽  
Author(s):  
Xiuzhuang Lang ◽  
Xiangmei Zhang ◽  
Daoquan Wang ◽  
Weiqing Zhou
Keyword(s):  
Liver Injury ◽  
Liver Microsomes ◽  
Metabolic Activation ◽  
Inhibitory Effect ◽  
Dependent Manner ◽  
Bioactive Constituents ◽  
Concentration Dependent Manner ◽  
Strong Inhibitory Effect

AbstractObacunone is one of the major bioactive constituents from Dictamni cortex, a traditional Chinese medicine widely used in China. Oral administration of obacunone or Dictamni cortex extract has been shown to cause liver injury in rats. Given that obacunone contains a furan ring, which is a structural alert, metabolic activation might be responsible for obacunone-induced liver injury. In this study, bioactivation pathways of obacunone in rat and human liver microsomes were investigated. Obacunone was first metabolized into cis-butene-1,4-dial, and then cis-butene-1,4-dial was captured by glutathione, N-acetyl-cysteine, and N-acetyl-lysine in the microsomal incubation system. A total of 13 adducts derived from the reaction of cis-butene-1,4-dial with glutathione and/or N-acetyl-lysine were detected and structurally identified by liquid chromatography coupled to high-resolution tandem mass spectrometry. The major metabolite (M7) was identified to be the cyclic mono-glutathione conjugate of cis-butene-1,4-dial, which was detected in bile and urine of obacunone-treated rats. M9 and M10, obacunone-derived glutathione-cis-butene-1,4-dial-NAL conjugates, were detected in the microsomal incubations of obacunone fortified with glutathione and N-acetyl-lysine as trapping agents. M3 and M4, pyrroline-2-one derivatives, were also detected in microsomal incubations. Further phenotyping studies indicated that ketoconazole showed a strong inhibitory effect on the production of cis-butene-1,4-dial in a concentration-dependent manner. CYP3A4 was demonstrated to be the primary enzyme responsible for the bioactivation of obacunone by using individual recombinant human CYP450 enzymes. The current study provides an overview of CYP450-dominated bioactivation of obacunone and contributes to the understanding of the role of bioactivation in obacunone-induced liver injury.

Effect of trans-resveratrol on 7-benzyloxy-4-trifluoromethylcoumarin O-dealkylation catalyzed by human recombinant CYP3A4 and CYP3A5

2001 ◽  
Vol 79 (3) ◽  
pp. 220-226 ◽  
Author(s):  
Thomas KH Chang ◽  
Rosita KY Yeung
Keyword(s):  
Cytochrome P450 ◽  
Catalytic Activity ◽  
Red Wine ◽  
Inhibitory Effect ◽  
Substrate Oxidation ◽  
Polyphenolic Compounds ◽  
Dependent Manner ◽  
Concentration Dependent Manner ◽  
Vitro Effect

Red wine concentrate has been reported to inhibit the catalytic activity of human recombinant cytochrome P450 (CYP) 3A4. Wine contains many polyphenolic compounds, including trans-resveratrol, which is also available commercially as a nutraceutical product. In the present study, we examined the in vitro effect of trans-resveratrol on human CYP3A catalytic activity by employing recombinant CYP3A4 and CYP3A5 as model enzymes and 7-benzyloxy-4-trifluoromethylcoumarin (BFC) as a CYP3A substrate. Trans-resveratrol inhibited BFC O-dealkylation catalyzed by CYP3A4 and CYP3A5 in a concentration-dependent manner. In each case, the inhibition was noncompetitive, as determined by Lineweaver-Burk and Dixon plots of the enzyme kinetic data. The apparent Ki values (mean ± SEM) for the inhibition by trans-resveratrol of BFC O-dealkylation catalyzed by CYP3A4 and CYP3A5 were 10.2 ± 1.1 µM and 14.7 ± 0.3 µM, respectively. Preincubation of trans-resveratrol with NADPH and CYP3A4 or CYP3A5 for 10 or 15 min prior to initiation of substrate oxidation did not enhance the inhibitory effect, suggesting that this compound was not a mechanism-based inactivator of CYP3A4 or CYP3A5 when BFC was used as the substrate. Overall, our study provides the first demonstration that trans-resveratrol inhibits, in vitro, a substrate oxidation reaction catalyzed by human recombinant CYP3A4 and CYP3A5.Key words: 7-benzyloxy-4-trifluoromethylcoumarin, cytochrome P450, CYP3A4, CYP3A5, 7-hydroxy-4-trifluoromethylcoumarin, nutraceutical, trans-resveratrol.

scholarly journals Alcohol-Induced Increase in the Content of CYP2E1 in Human Liver Microsomes Causes a Multifold Activation of CYP3A4 and Attenuates its Cooperativity

2020 ◽  
Author(s):  
Bikash Dangi ◽  
Nadezhda Y. Davydova ◽  
Nikita E. Vavilov ◽  
Victor G. Zgoda ◽  
Dmitri R. Davydov
Keyword(s):  
Cytochrome P450 ◽  
Human Liver ◽  
Liver Microsomes ◽  
Alcohol Exposure ◽  
Inhibitory Effect ◽  
Human Liver Microsomes ◽  
Specific Substrate ◽  
Physiological Relevance ◽  
Physical Interactions

AbstractHere we investigate the effect of alcohol-induced increase in the content of CYP2E1 in human liver microsomes (HLM) on the function of CYP3A4. In these studies we used a model that implements enrichment of HLM samples with CYP2E1 through membrane incorporation of the purified protein. Enrichment of HLM with CYP2E1 considerably increases the rate of metabolism of 7-benzyloxyquinoline (BQ) and attenuates the homotropic cooperativity observed with this CYP3A4-specific substrate. Incorporation of CYP2E1 also eliminates the activating effect of α-Naphthoflavone (ANF) on BQ metabolism seen in some untreated HLM samples. To probe the physiological relevance of these effects we compared three pooled preparations of HLM from normal donors (HLM-N) with a preparation obtained from heavy alcohol consumers (HLM-A). The composition of the P450 pool in all four samples was characterized with mass-spectrometric determination of 11 cytochrome P450 species. The molar content of CYP2E1 in HLM-A was from 2.5 to 3.3 times higher than that found in HLM-N. In contrast, the content of CYP3A4 in HLM-A was the lowest among all four HLM samples. Despite of that, HLM-A exhibited much higher rate of metabolism and lower degree of homotropic cooperativity with BQ, similar to that observed in CYP2E1-enriched HLM-N. In order to substantiate the hypothesis on the involvement of physical interactions between CYP2E1 and CYP3A4 in the observed effects we probed hetero-association of these proteins in Supersomes™ containing recombinant CYP3A4 with a technique based on homo-FRET and employing CYP2E1 labeled with BODIPY-618 maleimide. These experiments demonstrated high affinity interactions between the two enzymes and revealed an inhibitory effect of ANF on their hetero-association. Our results demonstrate that the catalytic activity and allosteric properties of CYP3A4 are fundamentally dependent on the composition of the cytochrome P450 ensemble and imply a profound impact of chronic alcohol exposure on the pharmacokinetics of drugs metabolized by CYP3A4.

scholarly journals Fulvestrant-3-Boronic Acid (ZB716) Demonstrates Oral Bioavailability and Favorable Pharmacokinetic Profile in Preclinical ADME Studies

2021 ◽  
Vol 14 (8) ◽  
pp. 719
Author(s):  
Jiawang Liu ◽  
Nirmal Rajasekaran ◽  
Ahamed Hossain ◽  
Changde Zhang ◽  
Shanchun Guo ◽  
...  
Keyword(s):  
Boronic Acid ◽  
Oral Bioavailability ◽  
Drug Exposure ◽  
Liver Microsomes ◽  
Pharmacokinetic Profile ◽  
Pharmacokinetic Studies ◽  
Dependent Manner ◽  
Mucosal Permeability ◽  
Time Curve ◽  
Concentration Dependent Manner

Fulvestrant-3-boronic acid (ZB716), an oral selective estrogen receptor degrader (SERD) under clinical development, has been investigated in ADME studies to characterize its absorption, metabolism, and pharmacokinetics. ZB716 was found to have high plasma protein binding in human and animal plasma, and low intestinal mucosal permeability. ZB716 had high clearance in hepatocytes of all species tested. ZB716 was metabolized primarily by CYP2D6 and CYP3A. In human liver microsomes, ZB716 demonstrated relatively low inhibition of CYP1A2, 2C8, 2C9, 2C19, 2D6, and 3A4 (when testosterone was used as the substrate), and no inhibition of CYP2B6 and 3A4 (when midazolam was used as the substrate). In assays for enzyme activity, ZB716 induced CYP1A2, 2B6, and 3A4 in a concentration-dependent manner. Single-dose and repeated-dose pharmacokinetic studies in rats and dogs showed oral bioavailability, dose-proportional drug exposure, and drug accumulation as measured by maximum concentration and area under the concentration–time curve (AUC).

scholarly journals Brassinolide Enhances the Level of Brassinosteroids, Protein, Pigments, and Monosaccharides in Wolffia arrhiza Treated with Brassinazole

Plants ◽  
2021 ◽  
Vol 10 (7) ◽  
pp. 1311
Author(s):  
Magdalena Chmur ◽  
Andrzej Bajguz
Keyword(s):  
Plant Growth ◽  
Growth And Development ◽  
Inhibitory Effect ◽  
Dependent Manner ◽  
Plant Growth And Development ◽  
Concentration Dependent Manner ◽  
Spectrophotometric Methods ◽  
Synthetic Inhibitor ◽  
Wolffia Arrhiza ◽  
First Time

Brassinolide (BL) represents brassinosteroids (BRs)—a group of phytohormones that are essential for plant growth and development. Brassinazole (Brz) is as a synthetic inhibitor of BRs’ biosynthesis. In the present study, the responses of Wolffia arrhiza to the treatment with BL, Brz, and the combination of BL with Brz were analyzed. The analysis of BRs and Brz was performed using LC-MS/MS. The photosynthetic pigments (chlorophylls, carotenes, and xanthophylls) levels were determined using HPLC, but protein and monosaccharides level using spectrophotometric methods. The obtained results indicated that BL and Brz influence W. arrhiza cultures in a concentration-dependent manner. The most stimulatory effects on the growth, level of BRs (BL, 24-epibrassinolide, 28-homobrassinolide, 28-norbrassinolide, catasterone, castasterone, 24-epicastasterone, typhasterol, and 6-deoxytyphasterol), and the content of pigments, protein, and monosaccharides, were observed in plants treated with 0.1 µM BL. Whereas the application of 1 µM and 10 µM Brz caused a significant decrease in duckweed weight and level of targeted compounds. Application of BL caused the mitigation of the Brz inhibitory effect and enhanced the BR level in duckweed treated with Brz. The level of BRs was reported for the first time in duckweed treated with BL and/or Brz.

Sign in / Sign up

Export Citation Format

Share Document