Biotransformation of Hexahydro-1,3,5-Trinitro-1,3,5-Triazine (RDX) by a Rabbit Liver Cytochrome P450: Insight into the Mechanism of RDX Biodegradation by Rhodococcus sp. Strain DN22

ABSTRACT A unique metabolite with a molecular mass of 119 Da (C2H5N3O3) accumulated during biotransformation of hexahydro-1,3,5-trinitro-1,3,5-triazine (RDX) by Rhodococcus sp. strain DN22 (D. Fournier, A. Halasz, J. C. Spain, P. Fiurasek, and J. Hawari, Appl. Environ. Microbiol. 68:166-172, 2002). The structure of the molecule and the reactions that led to its synthesis were not known. In the present study, we produced and purified the unknown metabolite by biotransformation of RDX with Rhodococcus sp. strain DN22 and identified the molecule as 4-nitro-2,4-diazabutanal using nuclear magnetic resonance and elemental analyses. Furthermore, we tested the hypothesis that a cytochrome P450 enzyme was responsible for RDX biotransformation by strain DN22. A cytochrome P450 2B4 from rabbit liver catalyzed a very similar biotransformation of RDX to 4-nitro-2,4-diazabutanal. Both the cytochrome P450 2B4 and intact cells of Rhodococcus sp. strain DN22 catalyzed the release of two nitrite ions from each reacted RDX molecule. A comparative study of cytochrome P450 2B4 and Rhodococcus sp. strain DN22 revealed substantial similarities in the product distribution and inhibition by cytochrome P450 inhibitors. The experimental evidence led us to propose that cytochrome P450 2B4 can catalyze two single electron transfers to RDX, thereby causing double denitration, which leads to spontaneous hydrolytic ring cleavage and decomposition to produce 4-nitro-2,4-diazabutanal. Our results provide strong evidence that a cytochrome P450 enzyme is the key enzyme responsible for RDX biotransformation by Rhodococcus sp. strain DN22.

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Endocannabinoid turnover in GtoPdb v.2021.3

IUPHAR/BPS Guide to Pharmacology CITE ◽

10.2218/gtopdb/f943/2021.3 ◽

2021 ◽

Vol 2021 (3) ◽

Author(s):

Stephen P.H. Alexander ◽

Patrick Doherty ◽

Christopher J. Fowler ◽

Jürg Gertsch ◽

Mario Van der Stelt

Keyword(s):

Cytochrome P450 ◽

Phospholipase D ◽

Cytochrome P450 Enzyme ◽

Facilitated Diffusion ◽

In Vitro Experiments ◽

Diacylglycerol Lipase ◽

P450 Enzyme ◽

Key Enzyme

The principle endocannabinoids are 2-acylglycerol esters, such as 2-arachidonoylglycerol (2-AG), and N-acylethanolamines, such as anandamide (N-arachidonoylethanolamine, AEA). The glycerol esters and ethanolamides are synthesised and hydrolysed by parallel, independent pathways. Mechanisms for release and re-uptake of endocannabinoids are unclear, although potent and selective inhibitors of facilitated diffusion of endocannabinoids across cell membranes have been developed [28]. FABP5 (Q01469) has been suggested to act as a canonical intracellular endocannabinoid transporter in vivo [17]. For the generation of 2-arachidonoylglycerol, the key enzyme involved is diacylglycerol lipase (DAGL), whilst several routes for anandamide synthesis have been described, the best characterized of which involves N-acylphosphatidylethanolamine-phospholipase D (NAPE-PLD, [70]). A transacylation enzyme which forms N-acylphosphatidylethanolamines has been identified as a cytosolic enzyme, PLA2G4E (Q3MJ16) [62]. In vitro experiments indicate that the endocannabinoids are also substrates for oxidative metabolism via cyclooxygenase, lipoxygenase and cytochrome P450 enzyme activities [5, 23, 72].

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Endocannabinoid turnover (version 2019.4) in the IUPHAR/BPS Guide to Pharmacology Database

IUPHAR/BPS Guide to Pharmacology CITE ◽

10.2218/gtopdb/f943/2019.4 ◽

2019 ◽

Vol 2019 (4) ◽

Author(s):

Stephen P.H. Alexander ◽

Patrick Doherty ◽

Christopher J. Fowler ◽

Jürg Gertsch ◽

Mario Van der Stelt

Keyword(s):

Cytochrome P450 ◽

Phospholipase D ◽

Cytochrome P450 Enzyme ◽

Facilitated Diffusion ◽

In Vitro Experiments ◽

Diacylglycerol Lipase ◽

P450 Enzyme ◽

Key Enzyme

The principle endocannabinoids are 2-acylglycerol esters, such as 2-arachidonoylglycerol (2-AG), and N-acylethanolamines, such as anandamide (N-arachidonoylethanolamine, AEA). The glycerol esters and ethanolamides are synthesised and hydrolysed by parallel, independent pathways. Mechanisms for release and re-uptake of endocannabinoids are unclear, although potent and selective inhibitors of facilitated diffusion of endocannabinoids across cell membranes have been developed [19]. FABP5 (Q01469) has been suggested to act as a canonical intracellular endocannabinoid transporter in vivo [12]. For the generation of 2-arachidonoylglycerol, the key enzyme involved is diacylglycerol lipase (DAGL), whilst several routes for anandamide synthesis have been described, the best characterized of which involves N-acylphosphatidylethanolamine-phospholipase D (NAPE-PLD, [49]). A transacylation enzyme which forms N-acylphosphatidylethanolamines has recently been identified as a cytosolic enzyme, PLA2G4E (Q3MJ16) [43]. In vitro experiments indicate that the endocannabinoids are also substrates for oxidative metabolism via cyclooxygenase, lipoxygenase and cytochrome P450 enzyme activities [4, 16, 51].

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The role of cytochrome P450 enzyme genetic variants in cannabis hyperemesis syndrome—A case report

Basic & Clinical Pharmacology & Toxicology ◽

10.1111/bcpt.13581 ◽

2021 ◽

Author(s):

Maxim Kuzin ◽

Franziskos Xepapadakos ◽

Isabel Scharrer ◽

Marc Augsburger ◽

Chin‐Bin Eap ◽

...

Keyword(s):

Cytochrome P450 ◽

Case Report ◽

Genetic Variants ◽

Cytochrome P450 Enzyme ◽

P450 Enzyme ◽

Cannabis Hyperemesis Syndrome

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Inter-species comparisons of hepatic cytochrome P450 enzyme levels in male ruminants

Archives of Toxicology ◽

10.1007/s00204-003-0477-4 ◽

2003 ◽

Vol 77 (10) ◽

pp. 555-560 ◽

Cited By ~ 22

Author(s):

Miroslav Machala ◽

Pavel Soucek ◽

Jir� Neca ◽

Robert Ulrich ◽

Jir� Lamka ◽

...

Keyword(s):

Cytochrome P450 ◽

Cytochrome P450 Enzyme ◽

P450 Enzyme ◽

Species Comparisons ◽

Hepatic Cytochrome

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Glutathione S-Transferases and Cytochrome P450 Enzyme Expression in Patients with Intracranial Tumors: Preliminary Report of 55 Patients

Medical Principles and Practice ◽

10.1159/000494496 ◽

2018 ◽

Vol 28 (1) ◽

pp. 56-62

Author(s):

Cahit Kural ◽

Arzu Kaya Kocdogan ◽

Gulcin Güler Şimşek ◽

Serpil Oğuztüzün ◽

Pınar Kaygın ◽

...

Keyword(s):

Cytochrome P450 ◽

Brain Tissue ◽

Pituitary Adenomas ◽

Normal Brain ◽

Cytochrome P450 Enzyme ◽

Intracranial Tumors ◽

Glutathione S Transferase ◽

Normal Brain Tissue ◽

Tissue Samples ◽

P450 Enzyme

Objective: Intracranial tumors are one of the most frightening and difficult-to-treat tumor types. In addition to surgery, protocols such as chemotherapy and radiotherapy also take place in the treatment. Glutathione S-transferase (GST) and cytochrome P450 (CYP) enzymes are prominent drug-metabolizing enzymes in the human body. The aim of this study is to show the expression of GSTP1, GSTM1, CYP1A1, and CYP1B1 in different types of brain tumors and compare our results with those in the literature. Subjects and Methods: The expression of GSTP1, GSTM1, CYP1A1, and CYP1B1 was analyzed using immunostaining in 55 patients with intracranial tumors in 2016–2017. For GST and CYP expression in normal brain tissue, samples of a portion of surrounding normal brain tissue as well as a matched far neighbor of tumor tissue were used. The demographic features of the patients were documented and the expression results compared. Results: The mean age of the patients was 46.72 years; 29 patients were female and 26 were male. Fifty-seven specimens were obtained from 55 patients. Among them, meningioma was diagnosed in 12, metastases in 12, glioblastoma in 9, and pituitary adenoma in 5. The highest GSTP1, GSTM1, and CYP1A1 expressions were observed in pituitary adenomas. The lowest GSTP1 expression was detected in glioblastomas and the lowest CYP1B1 expression in pituitary adenomas. Conclusion: GSTP1 and CYP expression is increased in intracranial tumors. These results should be confirmed with a larger series and different enzyme subtypes.

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Drug Interactions of Macrolides: Emphasis on Dirithromycin

Annals of Pharmacotherapy ◽

10.1177/106002809703100314 ◽

1997 ◽

Vol 31 (3) ◽

pp. 349-356 ◽

Cited By ~ 28

Author(s):

Vish S Watkins ◽

Ron E Polk ◽

Jennifer L Stotka

Keyword(s):

Cytochrome P450 ◽

Drug Interactions ◽

Ethinyl Estradiol ◽

Enzyme System ◽

Cytochrome P450 Enzyme ◽

Cytochrome P450 Enzymes ◽

Kidney Transplant Recipients ◽

P450 Enzyme ◽

Cytochrome P450 Enzyme System ◽

Clinically Significant

Objective To describe the drug interactions of dirithromycin, a new macrolide, and to compare them with those of other macrolides. Data Sources A literature search was performed using MEDLINE to identify articles published between January 1980 and July 1995 concerning the drug interactions of macrolides. Published abstracts were also examined. All studies using dirithromycin were performed under the sponsorship of Eli Lilly and Company. Data Synthesis Erythromycin, the first macrolide discovered, is metabolized by the cytochrome P450 enzyme system. By decreasing their metabolism, erythromycin can interact with other drugs metabolized by the cytochrome P450 enzymes. The lack of such interactions would be a desirable feature in a newer macrolide. We describe studies performed to detect any interactions of dirithromycin with cyclosporine, theophylline, terfenadine, warfarin, and ethinyl estradiol. The studies showed that dirithromycin, like azithromycin, is much less likely to cause the interactions detected with clarithromycin and erythromycin. A review of the literature showed differences among macrolides in their abilities to inhibit cytochrome P450 enzymes and, thus, to cause drug–drug interactions. Erythromycin and clarithromycin inhibit cytochrome P450 enzymes, and have been implicated in clinically significant interactions. Azithromycin and dirithromycin neither inhibit cytochrome P450 enzymes nor are implicated in clinically significant drug–drug interactions. Conclusions Dirithromycin, a new macrolide, does not inhibit the cytochrome P450 enzyme system. The concomitant use of dirithromycin with cyclosporine, theophylline, terfenadine, warfarin, or ethinyl estradiol was studied in pharmacokinetic and pharmacodynamic studies. In vitro, dirithromycin did not bind cytochrome P450. In healthy subjects, erythromycin increases the clearance of cyclosporine by 51%, whereas dirithromycin causes no significant changes in the pharmacokinetics of cyclosporine. In kidney transplant recipients, administration of dirithromycin was associated with a significant (p < 0.003) decrease of 17.4% in the clearance of cyclosporine. In patients taking low-dose estradiol, the administration of dirithromycin caused a significant (p < 0.03) increase of 9.9% in the clearance of ethinyl estradiol; escape ovulation did not occur. Unlike erythromycin and clarithromycin, dirithromycin had no significant effects on the pharmacokinetics of theophylline, terfenadine, or warfarin. The alterations typical of drug interactions that are based on inhibition of the cytochrome P450 system occurring with erythromycin and clarithromycin were not observed with dirithromycin.

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