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Pampalone G, Chiasserini D, Pierigè F, Camaioni E, Orvietani PL, Bregalda A, Menotta M, Bellezza I, Rossi L, Cellini B, Magnani M. Biochemical Studies on Human Ornithine Aminotransferase Support a Cell-Based Enzyme Replacement Therapy in the Gyrate Atrophy of the Choroid and Retina. Int J Mol Sci 2024; 25:7931. [PMID: 39063173 PMCID: PMC11277095 DOI: 10.3390/ijms25147931] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/24/2024] [Revised: 07/12/2024] [Accepted: 07/17/2024] [Indexed: 07/28/2024] Open
Abstract
The gyrate atrophy of the choroid and retina (GACR) is a rare genetic disease for which no definitive cure is available. GACR is due to the deficit of ornithine aminotransferase (hOAT), a pyridoxal 5'-phosphate-dependent enzyme responsible for ornithine catabolism. The hallmark of the disease is plasmatic ornithine accumulation, which damages retinal epithelium leading to progressive vision loss and blindness within the fifth decade. Here, we characterized the biochemical properties of tetrameric and dimeric hOAT and evaluated hOAT loaded in red blood cells (RBCs) as a possible enzyme replacement therapy (ERT) for GACR. Our results show that (i) hOAT has a relatively wide specificity for amino acceptors, with pyruvate being the most suitable candidate for ornithine catabolism within RBCs; (ii) both the tetrameric and dimeric enzyme can be loaded in RBC retaining their activity; and (iii) hOAT displays reduced stability in plasma, but is partly protected from inactivation upon incubation in a mixture mimicking the intracellular erythrocyte environment. Preliminary ex vivo experiments indicate that hOAT-loaded RBCs are able to metabolize extracellular ornithine at a concentration mimicking that found in patients, both in buffer and, although with lower efficiency, in plasma. Overall, our data provide a proof of concept that an RBC-mediated ERT is feasible and can be exploited as a new therapeutic approach in GACR.
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Affiliation(s)
- Gioena Pampalone
- Department of Medicine and Surgery, University of Perugia, P.le L. Severi 1, 06132 Perugia, Italy; (G.P.); (D.C.); (P.L.O.); (I.B.)
| | - Davide Chiasserini
- Department of Medicine and Surgery, University of Perugia, P.le L. Severi 1, 06132 Perugia, Italy; (G.P.); (D.C.); (P.L.O.); (I.B.)
| | - Francesca Pierigè
- Department of Biomolecular Sciences, University of Urbino Carlo Bo, 61029 Urbino, Italy; (F.P.); (A.B.); (M.M.); (M.M.)
| | - Emidio Camaioni
- Department of Pharmaceutical Sciences, University of Perugia, Via del Liceo 1, 06122 Perugia, Italy;
| | - Pier Luigi Orvietani
- Department of Medicine and Surgery, University of Perugia, P.le L. Severi 1, 06132 Perugia, Italy; (G.P.); (D.C.); (P.L.O.); (I.B.)
| | - Alessandro Bregalda
- Department of Biomolecular Sciences, University of Urbino Carlo Bo, 61029 Urbino, Italy; (F.P.); (A.B.); (M.M.); (M.M.)
| | - Michele Menotta
- Department of Biomolecular Sciences, University of Urbino Carlo Bo, 61029 Urbino, Italy; (F.P.); (A.B.); (M.M.); (M.M.)
| | - Ilaria Bellezza
- Department of Medicine and Surgery, University of Perugia, P.le L. Severi 1, 06132 Perugia, Italy; (G.P.); (D.C.); (P.L.O.); (I.B.)
| | - Luigia Rossi
- Department of Biomolecular Sciences, University of Urbino Carlo Bo, 61029 Urbino, Italy; (F.P.); (A.B.); (M.M.); (M.M.)
| | - Barbara Cellini
- Department of Medicine and Surgery, University of Perugia, P.le L. Severi 1, 06132 Perugia, Italy; (G.P.); (D.C.); (P.L.O.); (I.B.)
| | - Mauro Magnani
- Department of Biomolecular Sciences, University of Urbino Carlo Bo, 61029 Urbino, Italy; (F.P.); (A.B.); (M.M.); (M.M.)
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2
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Borsos E, Varga E, Aichinger G, Marko D. Unraveling Interspecies Differences in the Phase I Hepatic Metabolism of Alternariol and Alternariol Monomethyl Ether: Closing Data Gaps for a Comprehensive Risk Assessment. Chem Res Toxicol 2024. [PMID: 39028893 DOI: 10.1021/acs.chemrestox.4c00095] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 07/21/2024]
Abstract
The Alternaria mycotoxins alternariol (AOH) and alternariol 9-O-monomethyl ether (AME) are pervasive food contaminants known to exert adverse effects in vitro, yet their toxicokinetics remain inadequately understood. Thus, this study endeavors to elucidate the qualitative and quantitative aspects of the phase I metabolism of AOH and AME. To pursue this goal, reduced nicotinamide adenine dinucleotide phosphate (NADPH)-fortified porcine, rat, and human liver microsomes were incubated for 0-10 min with AOH or AME within a concentration range of 1-100 and 1-50 μM, respectively. The decline in the parent toxin concentration was monitored via liquid chromatography coupled to tandem mass spectrometry, whereas coupling to high-resolution mass spectrometry provided insights into the composition of the arising metabolic mixture. The collected quantitative data allowed us to calculate the hepatic intrinsic clearance rates of AOH and AME, marking a notable contribution to the field. Moreover, we unveiled interspecies differences in the pattern and rate of the phase I metabolism of the investigated mycotoxins. The presented findings lay the groundwork for physiologically based toxicokinetic modeling aimed at estimating local concentrations of these mycotoxins in specific organs, enhancing our understanding of their mode of action and adverse health effects.
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Affiliation(s)
- Eszter Borsos
- Department of Food Chemistry and Toxicology, Faculty of Chemistry, University of Vienna, Vienna 1090, Austria
- Doctoral School in Chemistry, Faculty of Chemistry, University of Vienna, Vienna 1090, Austria
| | - Elisabeth Varga
- Department of Food Chemistry and Toxicology, Faculty of Chemistry, University of Vienna, Vienna 1090, Austria
- Unit Food Hygiene and Technology, Centre for Food Science and Veterinary Public Health, Clinical Department for Farm Animals and Food System Science, University of Veterinary Medicine, Vienna, Vienna 1210, Austria
| | - Georg Aichinger
- Department of Food Chemistry and Toxicology, Faculty of Chemistry, University of Vienna, Vienna 1090, Austria
- Department of Health Sciences and Technology, ETH Zürich, Zürich 8092, Switzerland
| | - Doris Marko
- Department of Food Chemistry and Toxicology, Faculty of Chemistry, University of Vienna, Vienna 1090, Austria
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Leow JWH, Chan ECY. CYP2J2-mediated metabolism of arachidonic acid in heart: A review of its kinetics, inhibition and role in heart rhythm control. Pharmacol Ther 2024; 258:108637. [PMID: 38521247 DOI: 10.1016/j.pharmthera.2024.108637] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/18/2023] [Revised: 02/06/2024] [Accepted: 03/11/2024] [Indexed: 03/25/2024]
Abstract
Cytochrome P450 2 J2 (CYP2J2) is primarily expressed extrahepatically and is the predominant epoxygenase in human cardiac tissues. This highlights its key role in the metabolism of endogenous substrates. Significant scientific interest lies in cardiac CYP2J2 metabolism of arachidonic acid (AA), an omega-6 polyunsaturated fatty acid, to regioisomeric bioactive epoxyeicosatrienoic acid (EET) metabolites that show cardioprotective effects including regulation of cardiac electrophysiology. From an in vitro perspective, the accurate characterization of the kinetics of CYP2J2 metabolism of AA including its inhibition and inactivation by drugs could be useful in facilitating in vitro-in vivo extrapolations to predict drug-AA interactions in drug discovery and development. In this review, background information on the structure, regulation and expression of CYP2J2 in human heart is presented alongside AA and EETs as its endogenous substrate and metabolites. The in vitro and in vivo implications of the kinetics of this endogenous metabolic pathway as well as its perturbation via inhibition and inactivation by drugs are elaborated. Additionally, the role of CYP2J2-mediated metabolism of AA to EETs in cardiac electrophysiology will be expounded.
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Affiliation(s)
- Jacqueline Wen Hui Leow
- Department of Pharmacy, Faculty of Science, National University of Singapore, 18 Science Drive 4, Singapore 117543, Singapore
| | - Eric Chun Yong Chan
- Department of Pharmacy, Faculty of Science, National University of Singapore, 18 Science Drive 4, Singapore 117543, Singapore.
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4
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Hidayat R, Shoieb SM, Mosa FES, Barakat K, Brocks DR, Isse FA, Gerges SH, El-Kadi AOS. 16R-HETE and 16S-HETE alter human cytochrome P450 1B1 enzyme activity probably through an allosteric mechanism. Mol Cell Biochem 2024; 479:1379-1390. [PMID: 37436655 DOI: 10.1007/s11010-023-04801-4] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/26/2023] [Accepted: 06/25/2023] [Indexed: 07/13/2023]
Abstract
Cytochrome P450 1B1 (CYP1B1) has been widely associated with the development of cardiac pathologies due to its ability to produce cardiotoxic metabolites like midchain hydroxyeicosatetraenoic acids (HETEs) from arachidonic acid (AA) through an allylic oxidation reaction. 16-HETE is a subterminal HETE that is also produced by CYP-mediated AA metabolism. 19-HETE is another subterminal HETE that was found to inhibit CYP1B1 activity, lower midchain HETEs, and have cardioprotective effects. However, the effect of 16-HETE enantiomers on CYP1B1 has not yet been investigated. We hypothesized that 16(R/S)-HETE could alter the activity of CYP1B1 and other CYP enzymes. Therefore, this study was carried out to investigate the modulatory effect of 16-HETE enantiomers on CYP1B1 enzyme activity, and to examine the mechanisms by which they exert these modulatory effects. To investigate whether these effects are specific to CYP1B1, we also investigated 16-HETE modulatory effects on CYP1A2. Our results showed that 16-HETE enantiomers significantly increased CYP1B1 activity in RL-14 cells, recombinant human CYP1B1, and human liver microsomes, as seen by the significant increase in 7-ethoxyresorufin deethylation rate. On the contrary, 16-HETE enantiomers significantly inhibited CYP1A2 catalytic activity mediated by the recombinant human CYP1A2 and human liver microsomes. 16R-HETE showed stronger effects than 16S-HETE. The sigmoidal binding mode of the enzyme kinetics data demonstrated that CYP1B1 activation and CYP1A2 inhibition occurred through allosteric regulation. In conclusion, our study provides the first evidence that 16R-HETE and 16S-HETE increase CYP1B1 catalytic activity through an allosteric mechanism.
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Affiliation(s)
- Rahmat Hidayat
- Faculty of Pharmacy & Pharmaceutical Sciences, 2142J Katz Group-Rexall Centre for Pharmacy and Health Research, University of Alberta, Edmonton, AL, T6G 2E1, Canada
| | - Sherif M Shoieb
- Faculty of Pharmacy & Pharmaceutical Sciences, 2142J Katz Group-Rexall Centre for Pharmacy and Health Research, University of Alberta, Edmonton, AL, T6G 2E1, Canada
| | - Farag E S Mosa
- Faculty of Pharmacy & Pharmaceutical Sciences, 2142J Katz Group-Rexall Centre for Pharmacy and Health Research, University of Alberta, Edmonton, AL, T6G 2E1, Canada
| | - Khaled Barakat
- Faculty of Pharmacy & Pharmaceutical Sciences, 2142J Katz Group-Rexall Centre for Pharmacy and Health Research, University of Alberta, Edmonton, AL, T6G 2E1, Canada
| | - Dion R Brocks
- Faculty of Pharmacy & Pharmaceutical Sciences, 2142J Katz Group-Rexall Centre for Pharmacy and Health Research, University of Alberta, Edmonton, AL, T6G 2E1, Canada
| | - Fadumo A Isse
- Faculty of Pharmacy & Pharmaceutical Sciences, 2142J Katz Group-Rexall Centre for Pharmacy and Health Research, University of Alberta, Edmonton, AL, T6G 2E1, Canada
| | - Samar H Gerges
- Faculty of Pharmacy & Pharmaceutical Sciences, 2142J Katz Group-Rexall Centre for Pharmacy and Health Research, University of Alberta, Edmonton, AL, T6G 2E1, Canada
| | - Ayman O S El-Kadi
- Faculty of Pharmacy & Pharmaceutical Sciences, 2142J Katz Group-Rexall Centre for Pharmacy and Health Research, University of Alberta, Edmonton, AL, T6G 2E1, Canada.
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5
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Feng Y, Gong C, Zhu J, Liu G, Tang Y, Li W. Unraveling the Ligand-Binding Sites of CYP3A4 by Molecular Dynamics Simulations with Solvent Probes. J Chem Inf Model 2024; 64:3451-3464. [PMID: 38593186 DOI: 10.1021/acs.jcim.4c00089] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/11/2024]
Abstract
Cytochrome P450 3A4 (CYP3A4) is one of the most important drug-metabolizing enzymes in the human body and is well known for its complicated, atypical kinetic characteristics. The existence of multiple ligand-binding sites in CYP3A4 has been widely recognized as being capable of interfering with the active pocket through allosteric effects. The identification of ligand-binding sites other than the canonical active site above the heme is especially important for understanding the atypical kinetic characteristics of CYP3A4 and the intriguing association between the ligand and the receptor. In this study, we first employed mixed-solvent molecular dynamics (MixMD) simulations coupled with the online computational predictive tools to explore potential ligand-binding sites in CYP3A4. The MixMD approach demonstrates better performance in dealing with the receptor flexibility compared with other computational tools. From the sites identified by MixMD, we then picked out multiple sites for further exploration using ensemble docking and conventional molecular dynamics (cMD) simulations. Our results indicate that three extra sites are suitable for ligand binding in CYP3A4, including one experimentally confirmed site and two novel sites.
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Affiliation(s)
- Yanjun Feng
- Shanghai Frontiers Science Center of Optogenetic Techniques for Cell Metabolism, Shanghai Key Laboratory of New Drug Design, School of Pharmacy, East China University of Science and Technology, 130 Meilong Road, Shanghai 200237, China
| | - Changda Gong
- Shanghai Frontiers Science Center of Optogenetic Techniques for Cell Metabolism, Shanghai Key Laboratory of New Drug Design, School of Pharmacy, East China University of Science and Technology, 130 Meilong Road, Shanghai 200237, China
| | - Jieyu Zhu
- Shanghai Frontiers Science Center of Optogenetic Techniques for Cell Metabolism, Shanghai Key Laboratory of New Drug Design, School of Pharmacy, East China University of Science and Technology, 130 Meilong Road, Shanghai 200237, China
| | - Guixia Liu
- Shanghai Frontiers Science Center of Optogenetic Techniques for Cell Metabolism, Shanghai Key Laboratory of New Drug Design, School of Pharmacy, East China University of Science and Technology, 130 Meilong Road, Shanghai 200237, China
| | - Yun Tang
- Shanghai Frontiers Science Center of Optogenetic Techniques for Cell Metabolism, Shanghai Key Laboratory of New Drug Design, School of Pharmacy, East China University of Science and Technology, 130 Meilong Road, Shanghai 200237, China
| | - Weihua Li
- Shanghai Frontiers Science Center of Optogenetic Techniques for Cell Metabolism, Shanghai Key Laboratory of New Drug Design, School of Pharmacy, East China University of Science and Technology, 130 Meilong Road, Shanghai 200237, China
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6
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Lee J, Beers JL, Geffert RM, Jackson KD. A Review of CYP-Mediated Drug Interactions: Mechanisms and In Vitro Drug-Drug Interaction Assessment. Biomolecules 2024; 14:99. [PMID: 38254699 PMCID: PMC10813492 DOI: 10.3390/biom14010099] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2023] [Revised: 01/02/2024] [Accepted: 01/08/2024] [Indexed: 01/24/2024] Open
Abstract
Drug metabolism is a major determinant of drug concentrations in the body. Drug-drug interactions (DDIs) caused by the co-administration of multiple drugs can lead to alteration in the exposure of the victim drug, raising safety or effectiveness concerns. Assessment of the DDI potential starts with in vitro experiments to determine kinetic parameters and identify risks associated with the use of comedication that can inform future clinical studies. The diverse range of experimental models and techniques has significantly contributed to the examination of potential DDIs. Cytochrome P450 (CYP) enzymes are responsible for the biotransformation of many drugs on the market, making them frequently implicated in drug metabolism and DDIs. Consequently, there has been a growing focus on the assessment of DDI risk for CYPs. This review article provides mechanistic insights underlying CYP inhibition/induction and an overview of the in vitro assessment of CYP-mediated DDIs.
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Affiliation(s)
- Jonghwa Lee
- Division of Pharmacotherapy and Experimental Therapeutics, UNC Eshelman School of Pharmacy, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA; (J.L.B.); (R.M.G.)
| | | | | | - Klarissa D. Jackson
- Division of Pharmacotherapy and Experimental Therapeutics, UNC Eshelman School of Pharmacy, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA; (J.L.B.); (R.M.G.)
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7
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Zhang B, Chi H, Shen J, Tao Y, Lu Z, Lu F, Zhu P. Improved catalytic performance and molecular insight for lipoxygenase from Enterovibrio norvegicus via directed evolution. Front Bioeng Biotechnol 2023; 11:1305582. [PMID: 38047284 PMCID: PMC10690365 DOI: 10.3389/fbioe.2023.1305582] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/02/2023] [Accepted: 11/06/2023] [Indexed: 12/05/2023] Open
Abstract
Lipoxygenase (LOX) holds significant promise for food and pharmaceutical industries. However, albeit its application has been hampered by low catalytic activity and suboptimal thermostability. To address the drawbacks, a directed evolution strategy was explored to enhance the catalytic activity and thermostability of LOX from Enterovibrio norvegicus (EnLOX) for the first time. After two rounds of error-prone polymerase chain reaction (error-prone PCR) and one generations of sequential DNA shuffling, all of four different mutants showed a significant increase in the specific activity of EnLOX, ranging from 132.07 ± 9.34 to 330.17 ± 18.54 U/mg. Among these mutants, D95E/T99A/A121H/S142N/N444W/S613G (EAHNWG) exhibited the highest specific activity, which was 8.25-fold higher than the wild-type enzyme (WT). Meanwhile, the catalytic efficiency (K cat /K m) of EAHNWG was also improved, which was 13.61 ± 1.67 s-1 μM-1, in comparison to that of WT (4.83 ± 0.38 s-1 μM-1). In addition, mutant EAHNWG had a satisfied thermostability with the t 1/2,50 °C value of 6.44 ± 0.24 h, which was 0.4 h longer than that of the WT. Furthermore, the molecular dynamics simulation and structural analysis demonstrated that the reduction of hydrogen bonds number, the enhancement of hydrophobic interactions in the catalytic pocket, and the improvement of flexibility of the lid domain facilitated structural stability and the strength of substrate binding capacity for improved thermal stability and catalytic efficiency of mutant LOX after directed evolution. Overall, these results could provide the guidance for further enzymatic modification of LOX with high catalytic performance for industrial application.
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Affiliation(s)
| | | | | | | | | | - Fengxia Lu
- College of Food Science and Technology, Nanjing Agricultural University, Nanjing, China
| | - Ping Zhu
- College of Food Science and Technology, Nanjing Agricultural University, Nanjing, China
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8
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Sahil M, Singh T, Ghosh S, Mondal J. 3site Multisubstrate-Bound State of Cytochrome P450cam. J Am Chem Soc 2023; 145:23488-23502. [PMID: 37867463 DOI: 10.1021/jacs.3c06144] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/24/2023]
Abstract
We identified a multisubstrate-bound state, hereby referred as a 3site state, in cytochrome P450cam via integrating molecular dynamics simulation with nuclear magnetic resonance (NMR) pseudocontact shift measurements. The 3site state is a result of simultaneous binding of three camphor molecules in three locations around P450cam: (a) in a well-established "catalytic" site near heme, (b) in a kink-separated "waiting" site along channel-1, and (c) in a previously reported "allosteric" site at E, F, G, and H helical junctions. These three spatially distinct binding modes in the 3site state mutually communicate with each other via homotropic allostery and act cooperatively to render P450cam functional. The 3site state shows a significantly superior fit with NMR pseudo contact shift (PCS) data with a Q-score of 0.045 than previously known bound states and consists of D251 free of salt-bridges with K178 and R186, rendering the enzyme functionally primed. To date, none of the reported cocomplex of P450cam with its redox partner putidaredoxin (pdx) has been able to match solution NMR data and controversial pdx-induced opening of P450cam's channel-1 remains a matter of recurrent discourse. In this regard, inclusion of pdx to the 3site state is able to perfectly fit the NMR PCS measurement with a Q-score of 0.08 and disfavors the pdx-induced opening of channel-1, reconciling previously unexplained remarkably fast hydroxylation kinetics with a koff of 10.2 s-1. Together, our findings hint that previous experimental observations may have inadvertently captured the 3site state as an in vitro solution state, instead of the catalytic state alone, and provided a distinct departure from the conventional understanding of cytochrome P450.
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Affiliation(s)
- Mohammad Sahil
- Tata Institute of Fundamental Research, Hyderabad 500046, India
| | - Tejender Singh
- Tata Institute of Fundamental Research, Hyderabad 500046, India
| | - Soumya Ghosh
- Tata Institute of Fundamental Research, Hyderabad 500046, India
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Paweł R, Aleksandra U, Elżbieta R. Enzymatic kinetics of photosystem II with DCBQ as a substrate in extended Michaelis-Menten model. JOURNAL OF PHOTOCHEMISTRY AND PHOTOBIOLOGY. B, BIOLOGY 2023; 247:112780. [PMID: 37678075 DOI: 10.1016/j.jphotobiol.2023.112780] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/13/2023] [Revised: 08/17/2023] [Accepted: 08/24/2023] [Indexed: 09/09/2023]
Abstract
This study aimed to examine enzymatic kinetics of photosystem II (PSII) of maize mesophyll chloroplasts using the artificial electron acceptor 2,6-dichloro-1,4-benzoquinone (DCBQ) as a substrate. We extended Michealis-Menten kinetics model assuming that DCBQ can accept electrons from PSII in two ways: from a QB directly or from QA by docking in the QB site. We used a Clark oxygen electrode for measuring the PSII activity, depending on the concentration of DCBQ. We found that: [1] DCBQ acts as an electron acceptor or [2] as an inhibitor for PSII. At a concentration < 0.2 mM, DCBQ accepted electrons from the QB at a rate of 889 electrons/s, while at >> 0.2 mM it replaced QB following which the activity decreased to zero. DCBQ located in the QB also increased the affinity of the substrate to PSII. We determined the kinetic parameters for the chloroplasts of plants growing under high and low light intensity, to change thylakoid stacking and thus the rate of electron transport. The parameter KmB, which is a measure of the affinity of DCBQ to PSII, showed quantitative changes based on light intensity, while K was proportional to the size of the plastoquinone pool. We believe that our model can be applied as a tool to study "State transitions" and induced changes in grana stacking in plants exposed to various stresses, which will facilitate the regulation of electron transfer pathways through an appropriate balance between linear and cyclic electron transport.
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Affiliation(s)
- Rogowski Paweł
- Department of Molecular Plant Physiology, Institute of Environmental Biology, Faculty of Biology, University of Warsaw, Miecznikowa 1, 02-096 Warsaw, Poland.
| | - Urban Aleksandra
- Department of Molecular Plant Physiology, Institute of Environmental Biology, Faculty of Biology, University of Warsaw, Miecznikowa 1, 02-096 Warsaw, Poland.
| | - Romanowska Elżbieta
- Department of Molecular Plant Physiology, Institute of Environmental Biology, Faculty of Biology, University of Warsaw, Miecznikowa 1, 02-096 Warsaw, Poland.
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10
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Potęga A, Rafalska D, Kazimierczyk D, Kosno M, Pawłowicz A, Andrałojć W, Paluszkiewicz E, Laskowski T. In Vitro Enzyme Kinetics and NMR-Based Product Elucidation for Glutathione S-Conjugation of the Anticancer Unsymmetrical Bisacridine C-2028 in Liver Microsomes and Cytosol: Major Role of Glutathione S-Transferase M1-1 Isoenzyme. Molecules 2023; 28:6812. [PMID: 37836655 PMCID: PMC10574777 DOI: 10.3390/molecules28196812] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2023] [Revised: 09/21/2023] [Accepted: 09/26/2023] [Indexed: 10/15/2023] Open
Abstract
This work is the next step in studying the interplay between C-2028 (anticancer-active unsymmetrical bisacridine developed in our group) and the glutathione S-transferase/glutathione (GST/GSH) system. Here, we analyzed the concentration- and pH-dependent GSH conjugation of C-2028 in rat liver microsomes and cytosol. We also applied three recombinant human GST isoenzymes, which altered expression was found in various tumors. The formation of GSH S-conjugate of C-2028 in liver subfractions followed Michaelis-Menten kinetics. We found that C-2028 was conjugated with GSH preferentially by GSTM1-1, revealing a sigmoidal kinetic model. Using a colorimetric assay (MTT test), we initially assessed the cellular GST/GSH-dependent biotransformation of C-2028 in relation to cytotoxicity against Du-145 human prostate cancer cells in the presence or absence of the modulator of GSH biosynthesis. Pretreatment of cells with buthionine sulfoximine resulted in a cytotoxicity decrease, suggesting a possible GSH-mediated bioactivation process. Altogether, our results confirmed the importance of GSH conjugation in C-2028 metabolism, which humans must consider when planning a treatment strategy. Finally, nuclear magnetic resonance spectroscopy elucidated the structure of the GSH-derived product of C-2028. Hence, synthesizing the compound standard necessary for further advanced biological and bioanalytical investigations will be achievable.
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Affiliation(s)
- Agnieszka Potęga
- Department of Pharmaceutical Technology and Biochemistry, Faculty of Chemistry, Gdańsk University of Technology, Gabriela Narutowicza Str. 11/12, 80-233 Gdańsk, Poland; (D.R.); (D.K.); (M.K.); (E.P.); (T.L.)
| | - Dominika Rafalska
- Department of Pharmaceutical Technology and Biochemistry, Faculty of Chemistry, Gdańsk University of Technology, Gabriela Narutowicza Str. 11/12, 80-233 Gdańsk, Poland; (D.R.); (D.K.); (M.K.); (E.P.); (T.L.)
| | - Dawid Kazimierczyk
- Department of Pharmaceutical Technology and Biochemistry, Faculty of Chemistry, Gdańsk University of Technology, Gabriela Narutowicza Str. 11/12, 80-233 Gdańsk, Poland; (D.R.); (D.K.); (M.K.); (E.P.); (T.L.)
| | - Michał Kosno
- Department of Pharmaceutical Technology and Biochemistry, Faculty of Chemistry, Gdańsk University of Technology, Gabriela Narutowicza Str. 11/12, 80-233 Gdańsk, Poland; (D.R.); (D.K.); (M.K.); (E.P.); (T.L.)
| | - Aleksandra Pawłowicz
- Institute of Bioorganic Chemistry, Polish Academy of Sciences, Zygmunta Noskowskiego Str. 12/14, 61-704 Poznań, Poland; (A.P.); (W.A.)
| | - Witold Andrałojć
- Institute of Bioorganic Chemistry, Polish Academy of Sciences, Zygmunta Noskowskiego Str. 12/14, 61-704 Poznań, Poland; (A.P.); (W.A.)
| | - Ewa Paluszkiewicz
- Department of Pharmaceutical Technology and Biochemistry, Faculty of Chemistry, Gdańsk University of Technology, Gabriela Narutowicza Str. 11/12, 80-233 Gdańsk, Poland; (D.R.); (D.K.); (M.K.); (E.P.); (T.L.)
| | - Tomasz Laskowski
- Department of Pharmaceutical Technology and Biochemistry, Faculty of Chemistry, Gdańsk University of Technology, Gabriela Narutowicza Str. 11/12, 80-233 Gdańsk, Poland; (D.R.); (D.K.); (M.K.); (E.P.); (T.L.)
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11
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Pan J, Wu C, Tan R, Liao Y, Zhao G, Li W, Peng Y, Li W, Zheng J. Difference in hepatotoxicity of furan-containing components in cortex dictamni correlates the efficiency of their metabolic activation. PHYTOMEDICINE : INTERNATIONAL JOURNAL OF PHYTOTHERAPY AND PHYTOPHARMACOLOGY 2023; 114:154778. [PMID: 36996529 DOI: 10.1016/j.phymed.2023.154778] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/18/2023] [Revised: 03/03/2023] [Accepted: 03/16/2023] [Indexed: 06/19/2023]
Abstract
BACKGROUND Cortex Dictamni (CD) has been associated with an increased risk of liver injury, which may be attributable to the metabolic activation of its furan-containing components (FCC). However, the hepatotoxic potencies of these FCCs and the mechanisms behind the differences in their toxicity intensity remain unknown. METHODS The constituents of CD extract were determined by LC-MS/MS. Potentially toxic FCCs were screened by a previously published method. Hepatotoxicity of potentially toxic FCCs was evaluated in cultured mouse primary hepatocytes and mice. The ability to deplete hepatic glutathione (GSH), along with the formation of the corresponding GSH conjugates, resulting from the metabolic activation was determined ex vivo in mice. Intrinsic clearance rates (CLint,Vmax/Km) were assessed by a microsome-bases assay. RESULTS A total of 18 FCCs were detected in CD extract. Among them, four FCCs, including rutaevin (RUT), limonin (LIM), obacunone (OBA) and fraxinellone (FRA) were found to be bioactivated in microsomal incubations. Only FRA displayed significant hepatotoxicity in vitro and in vivo. Similarly, FRA caused GSH depletion and GSH conjugation the most in vivo. The order of CLint for the four FCCs was FRA>>OBA>LIM>RUT. CONCLUSION FRA is the major toxic FCC component of hepatotoxic CD extract. The hepatotoxicity of FCCs is closely related to the efficiency of their metabolic activation.
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Affiliation(s)
- Jie Pan
- State Key Laboratory of Functions and Applications of Medicinal Plants, Guizhou Provincial Key Laboratory of Pharmaceutics, Guizhou Medical University, Guiyang, Guizhou 550004, PR China; School of Basic Medicine, Guizhou Medical University, Guiyang, Guizhou 550004, PR China; School of Pharmacy, Guizhou Medical University, Guiyang, Guizhou 550004, PR China; Engineering Research Center for the Development and Application of Ethnic Medicine and TCM, Ministry of Education, Guiyang, Guizhou 550004, PR China
| | - Chutian Wu
- State Key Laboratory of Functions and Applications of Medicinal Plants, Guizhou Provincial Key Laboratory of Pharmaceutics, Guizhou Medical University, Guiyang, Guizhou 550004, PR China; School of Pharmacy, Guizhou Medical University, Guiyang, Guizhou 550004, PR China
| | - Rong Tan
- School of Basic Medicine, Guizhou Medical University, Guiyang, Guizhou 550004, PR China
| | - Yufen Liao
- State Key Laboratory of Functions and Applications of Medicinal Plants, Guizhou Provincial Key Laboratory of Pharmaceutics, Guizhou Medical University, Guiyang, Guizhou 550004, PR China; School of Pharmacy, Guizhou Medical University, Guiyang, Guizhou 550004, PR China
| | - Guode Zhao
- Wuya College of Innovation, Shenyang Pharmaceutical University, Shenyang, Liaoning 110016, PR China
| | - Wei Li
- Wuya College of Innovation, Shenyang Pharmaceutical University, Shenyang, Liaoning 110016, PR China
| | - Ying Peng
- Wuya College of Innovation, Shenyang Pharmaceutical University, Shenyang, Liaoning 110016, PR China.
| | - Weiwei Li
- State Key Laboratory of Functions and Applications of Medicinal Plants, Guizhou Provincial Key Laboratory of Pharmaceutics, Guizhou Medical University, Guiyang, Guizhou 550004, PR China; School of Pharmacy, Guizhou Medical University, Guiyang, Guizhou 550004, PR China; Engineering Research Center for the Development and Application of Ethnic Medicine and TCM, Ministry of Education, Guiyang, Guizhou 550004, PR China.
| | - Jiang Zheng
- State Key Laboratory of Functions and Applications of Medicinal Plants, Guizhou Provincial Key Laboratory of Pharmaceutics, Guizhou Medical University, Guiyang, Guizhou 550004, PR China; School of Pharmacy, Guizhou Medical University, Guiyang, Guizhou 550004, PR China; Engineering Research Center for the Development and Application of Ethnic Medicine and TCM, Ministry of Education, Guiyang, Guizhou 550004, PR China; Wuya College of Innovation, Shenyang Pharmaceutical University, Shenyang, Liaoning 110016, PR China.
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Leow JWH, Gu Y, Chan ECY. Investigating the relevance of CYP2J2 inhibition for drugs known to cause intermediate to high risk torsades de pointes. Eur J Pharm Sci 2023; 187:106475. [PMID: 37225005 DOI: 10.1016/j.ejps.2023.106475] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2022] [Revised: 04/10/2023] [Accepted: 05/21/2023] [Indexed: 05/26/2023]
Abstract
Cardiac cytochrome P450 2J2 (CYP2J2) metabolizes endogenous polyunsaturated fatty acid, arachidonic acid (AA), to bioactive regioisomeric epoxyeicosatrienoic acid (EET) metabolites. This endogenous metabolic pathway has been postulated to play a homeostatic role in cardiac electrophysiology. However, it is unknown if drugs that cause intermediate to high risk torsades de pointes (TdP) exhibit inhibitory effects against CYP2J2 metabolism of AA to EETs. In this study, we demonstrated that 11 out of 16 drugs screened with intermediate to high risk of TdP as defined by the Comprehensive in vitro Proarrhythmia Assay (CiPA) initiative are concurrently reversible inhibitors of CYP2J2 metabolism of AA, with unbound inhibitory constant (Ki,AA,u) values ranging widely from 0.132 to 19.9 µM. To understand the physiological relevancy of Ki,AA,u, the in vivo unbound drug concentration within human heart tissue (Cu,heart) was calculated via experimental determination of in vitro unbound partition coefficient (Kpuu) for 10 CYP2J2 inhibitors using AC16 human ventricular cardiomyocytes as well as literature-derived values of fraction unbound in plasma (fu,p) and plasma drug concentrations in clinical scenarios leading to TdP. Notably, all CYP2J2 inhibitors screened belonging to the high TdP risk category, namely vandetanib and bepridil, exhibited highest Kpuu values of 18.2 ± 1.39 and 7.48 ± 1.16 respectively although no clear relationship between Cu,heart and risk of TdP could eventually be determined. R values based on basic models of reversible inhibition as per FDA guidelines were calculated using unbound plasma drug concentrations (Cu,plasma) and adapted using Cu,heart which suggested that 4 out of 10 CYP2J2 inhibitors with intermediate to high risk of TdP demonstrate greatest potential for clinically relevant in vivo cardiac drug-AA interactions. Our results shed novel insights on the relevance of CYP2J2 inhibition in drugs with risk of TdP. Further studies ascertaining the role of CYP2J2 metabolism of AA in cardiac electrophysiology, characterizing inherent cardiac ion channel activities of drugs with risk of TdP as well as in vivo evidence of drug-AA interactions will be required prior to determining if CYP2J2 inhibition could be an alternative mechanism contributing to drug-induced TdP.
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Affiliation(s)
- Jacqueline Wen Hui Leow
- Department of Pharmacy, Faculty of Science, National University of Singapore, 18 Science Drive 4, Singapore, 117543
| | - Yuxiang Gu
- Department of Pharmacy, Faculty of Science, National University of Singapore, 18 Science Drive 4, Singapore, 117543; School of Chemistry and Chemical Engineering, Harbin Institute of Technology, Harbin, Heilongjiang, 150001, China
| | - Eric Chun Yong Chan
- Department of Pharmacy, Faculty of Science, National University of Singapore, 18 Science Drive 4, Singapore, 117543.
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13
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Ni Y, Luo Z, Lv Y, Ma S, Luo C, Du D. Thimerosal, a competitive thioredoxin reductase 1 (TrxR1) inhibitor discovered via high-throughput screening. Biochem Biophys Res Commun 2023; 650:117-122. [PMID: 36780763 DOI: 10.1016/j.bbrc.2023.02.014] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/21/2023] [Accepted: 02/06/2023] [Indexed: 02/11/2023]
Abstract
Thioredoxin reductase 1 (TrxR1) is considered as an important anti-cancer drug target, inhibition of which can induce reactive oxygen species (ROS)-mediated apoptosis of human cancer cells. Here, we developed and optimized a high-throughput screening (HTS) assay based on enzyme kinetics for the discovery of TrxR1 inhibitors. By utilizing this assay, we performed a HTS for 2500 compounds from an in-house library against TrxR1. We found that a vaccine preservative, thimerosal, strongly inhibited TrxR1 in a competitive and reversible manner with an IC50 of 24.08 ± 0.86 nM. In addition, we determined that thiomersal has an inhibitory effect on the proliferation of A549 lung cancer cell line, with a GI50 of 6.81 ± 0.09 μM, slightly more potent than auranofin (GI50 = 11.85 ± 0.56 μM). Furthermore, we showed by flow cytometer that thimerosal effectively increased the content of ROS in A549 cells. Therefore, our work provided a high-throughput screening assay to quickly and effectively discover TrxR1 inhibitors, identifying thiomersal as a novel TrxR1 inhibitor and chemical probe.
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Affiliation(s)
- Yicheng Ni
- School of Pharmaceutical Science and Technology, Hangzhou Institute for Advanced Study, University of Chinese Academy of Sciences, Hangzhou, 310024, China; Drug Discovery and Design Center, The Center for Chemical Biology, State Key Laboratory of Drug Research, Shanghai Institute of Materia Medica, Chinese Academy of Sciences, Shanghai, 201203, China
| | - Zhongyuan Luo
- Drug Discovery and Design Center, The Center for Chemical Biology, State Key Laboratory of Drug Research, Shanghai Institute of Materia Medica, Chinese Academy of Sciences, Shanghai, 201203, China
| | - Yixin Lv
- School of Pharmaceutical Science and Technology, Hangzhou Institute for Advanced Study, University of Chinese Academy of Sciences, Hangzhou, 310024, China
| | - Shuyuan Ma
- School of Pharmaceutical Science and Technology, Hangzhou Institute for Advanced Study, University of Chinese Academy of Sciences, Hangzhou, 310024, China; Drug Discovery and Design Center, The Center for Chemical Biology, State Key Laboratory of Drug Research, Shanghai Institute of Materia Medica, Chinese Academy of Sciences, Shanghai, 201203, China
| | - Cheng Luo
- School of Pharmaceutical Science and Technology, Hangzhou Institute for Advanced Study, University of Chinese Academy of Sciences, Hangzhou, 310024, China; Drug Discovery and Design Center, The Center for Chemical Biology, State Key Laboratory of Drug Research, Shanghai Institute of Materia Medica, Chinese Academy of Sciences, Shanghai, 201203, China
| | - Daohai Du
- Drug Discovery and Design Center, The Center for Chemical Biology, State Key Laboratory of Drug Research, Shanghai Institute of Materia Medica, Chinese Academy of Sciences, Shanghai, 201203, China.
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14
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Sánchez-Trasviña C, Galindo-Estrada JD, Tinoco-Valencia R, Serrano-Carreón L, Rito-Palomares M, Willson RC, Mayolo-Deloisa K. Laccase-luminol chemiluminescence system: an investigation of substrate inhibition. LUMINESCENCE 2023; 38:341-349. [PMID: 36760184 DOI: 10.1002/bio.4460] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2022] [Revised: 01/31/2023] [Accepted: 02/05/2023] [Indexed: 02/11/2023]
Abstract
Chemiluminescence (CL) reactions are widely used for the detection and quantification of many types of analytes. Laccase has previously been proposed in CL reactions; however, its light emission behaviour has not been characterized. This study was conducted to characterize the laccase-luminol system, determine its kinetic parameters, and analyze the effects of protein and OH- concentration on the CL signal. Laccase from Coriolopsis gallica was combined with different concentrations of luminol (125 nM to 4 mM), and the enzyme kinetics were evaluated using diverse kinetic models. The laccase-luminol system was able to produce CL without an intermediate molecule, but it exhibited substrate-inhibition behaviour. A two-site random model was used and suggested that when the first luminol molecule was bound to the active site, laccase affinity for the second luminol molecule was increased. This inhibition effect could be avoided using a low luminol concentration. At 5 μM luminol concentration, 1 mg/ml (0.13 U) laccase is needed to achieve nearly 90% of the maximum CL signal, suggesting that the available luminol could not bind to all active sites. Furthermore, the concentration of NaOH negatively affected the CL signal. The laccase-luminol system represents an alternative to existing CL systems, with potential uses in molecular detection and quantification.
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Affiliation(s)
- Calef Sánchez-Trasviña
- Tecnologico de Monterrey, The Institute for Obesity Research, Av. Eugenio Garza Sada 2501 Sur, Monterrey, NL, Mexico.,Tecnologico de Monterrey, Escuela de Ingeniería y Ciencias, Centro de Biotecnología-FEMSA, Av. Eugenio Garza Sada 2501 Sur, Monterrey, NL, Mexico
| | - José Daniel Galindo-Estrada
- Universidad Politécnica del Valle de Toluca, Carretera Toluca-Almoloya de Juárez km. 5.6, Almoloya de Juárez, Estado de México, Mexico
| | - Raunel Tinoco-Valencia
- Instituto de Biotecnología, Universidad Nacional Autónoma de México, Av. Universidad 2001, Col. Chamilpa, Cuernavaca, Morelos, Mexico
| | - Leobardo Serrano-Carreón
- Instituto de Biotecnología, Universidad Nacional Autónoma de México, Av. Universidad 2001, Col. Chamilpa, Cuernavaca, Morelos, Mexico
| | - Marco Rito-Palomares
- Tecnologico de Monterrey, The Institute for Obesity Research, Av. Eugenio Garza Sada 2501 Sur, Monterrey, NL, Mexico.,Tecnologico de Monterrey, Escuela de Medicina y Ciencias de la Salud, Av. Morones Prieto 3000 Pte, Monterrey, NL, Mexico
| | - Richard C Willson
- Tecnologico de Monterrey, Escuela de Medicina y Ciencias de la Salud, Av. Morones Prieto 3000 Pte, Monterrey, NL, Mexico.,Department of Chemical and Biomolecular Engineering, University of Houston, Houston, TX, USA
| | - Karla Mayolo-Deloisa
- Tecnologico de Monterrey, The Institute for Obesity Research, Av. Eugenio Garza Sada 2501 Sur, Monterrey, NL, Mexico.,Tecnologico de Monterrey, Escuela de Ingeniería y Ciencias, Centro de Biotecnología-FEMSA, Av. Eugenio Garza Sada 2501 Sur, Monterrey, NL, Mexico.,Institute of Materials Science of Barcelona (ICMAB-CSIC), Campus UAB, Bellaterra, Spain
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15
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Biotransformation of phenytoin in the electrochemically-driven CYP2C19 system. Biophys Chem 2022; 291:106894. [PMID: 36174335 DOI: 10.1016/j.bpc.2022.106894] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/08/2022] [Revised: 09/08/2022] [Accepted: 09/13/2022] [Indexed: 11/21/2022]
Abstract
The possibility of the detection of atypical kinetic profiles of drug biotransformation using electrochemical systems based on immobilized cytochromes P450 with phenytoin hydroxylation by cytochrome P450 2C19 (CYP2C19) as an example was evaluated for the first time. For this purpose, we developed an electrochemical system, where one of the electrodes was modified by didodecyldimethylammonium bromide (DDAB) and was used as an electron donor for reduction of heme iron ion of the immobilized CYP2C19 and initiation of the catalytic reaction, while the second electrode was not modified and served for an electrochemical quantitation of 4-hydroxyphenytoin, which is a metabolite of antiepileptic drug phenytoin, by its oxidation peak. It was revealed that the dependence of the rate of 4-hydroxyphenytoin formation on phenytoin concentration is described by the equation for two enzymes or two binding sites indicating the existing of high- and low-affinity forms of the enzyme. The atypical kinetics and the kinetic parameters of CYP2C19-mediated phenytoin hydroxylation in the electrochemical system correlate to the same characteristics obtained by other authors in an alternative enzymatic system. Our results demonstrate the possibility of electrochemical systems based on cytochromes P450 to be applied for the detection of atypical kinetic profiles of drug metabolism.
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16
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Zhang B, Chen M, Xia B, Lu Z, Khoo KS, Show PL, Lu F. Characterization and Preliminary Application of a Novel Lipoxygenase from Enterovibrio norvegicus. Foods 2022; 11:foods11182864. [PMID: 36140992 PMCID: PMC9498203 DOI: 10.3390/foods11182864] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/24/2022] [Revised: 09/06/2022] [Accepted: 09/12/2022] [Indexed: 11/16/2022] Open
Abstract
Lipoxygenases have proven to be a potential biocatalyst for various industrial applications. However, low catalytic activity, low thermostability, and narrow range of pH stability largely limit its application. Here, a lipoxygenase (LOX) gene from Enterovibrio norvegicus DSM 15893 (EnLOX) was cloned and expressed in Escherichia coli BL21 (DE3). EnLOX showed the catalytic activity of 40.34 U mg−1 at 50 °C, pH 8.0. Notably, the enzyme showed superior thermostability, and wide pH range stability. EnLOX remained above 50% of its initial activity after heat treatment below 50 °C for 6 h, and its melting point temperature reached 78.7 °C. More than 70% of its activity was maintained after incubation at pH 5.0–9.5 and 4 °C for 10 h. In addition, EnLOX exhibited high substrate specificity towards linoleic acid, and its kinetic parameters of Vmax, Km, and Kcat values were 12.42 mmol min−1 mg−1, 3.49 μmol L−1, and 16.86 s−1, respectively. LC-MS/MS analysis indicated that EnLOX can be classified as 13-LOX, due to its ability to catalyze C18 polyunsaturated fatty acid to form 13-hydroxy fatty acid. Additionally, EnLOX could improve the farinograph characteristics and rheological properties of wheat dough. These results reveal the potential applications of EnLOX in the food industry.
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Affiliation(s)
- Bingjie Zhang
- College of Food Science and Technology, Nanjing Agricultural University, Nanjing 210095, China
| | - Meirong Chen
- College of Food Science and Technology, Nanjing Agricultural University, Nanjing 210095, China
| | - Bingjie Xia
- College of Food Science and Technology, Nanjing Agricultural University, Nanjing 210095, China
| | - Zhaoxin Lu
- College of Food Science and Technology, Nanjing Agricultural University, Nanjing 210095, China
| | - Kuan Shiong Khoo
- Department of Chemical Engineering and Materials Science, Yuan Ze University, Taoyuan 32003, Taiwan
| | - Pau Loke Show
- Faculty of Science and Engineering, University of Nottingham Malaysia, Jalan Broga, Semenyih 43500, Malaysia
| | - Fengxia Lu
- College of Food Science and Technology, Nanjing Agricultural University, Nanjing 210095, China
- Correspondence:
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17
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Sawyer CW, Tuey SM, West RE, Nolin TD, Joy MS. Physiologically Based Pharmacokinetic Modeling of Vitamin D 3 and Metabolites in Vitamin D-Insufficient Patients. Drug Metab Dispos 2022; 50:1161-1169. [PMID: 35779863 PMCID: PMC9450961 DOI: 10.1124/dmd.121.000609] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/12/2021] [Accepted: 06/13/2022] [Indexed: 11/22/2022] Open
Abstract
A physiologically based pharmacokinetic (PBPK) model of vitamin D3 and metabolites [25(OH)D3, 1,25(OH)2D3, and 24,25(OH)2D3] is presented. In this study, patients with 25(OH)D3 plasma concentrations below 30 ng/ml were studied after a single dose of 5000 I.U. (125 µg) cholecalciferol, provided with 5000 I.U. daily cholecalciferol supplementation until vitamin D replete [25(OH)D3 plasma concentrations above 30 ng/ml], and had serial plasma samples were collected at each phase for 14 days. Total concentrations of vitamin D3 and metabolites were measured by ultra-high performance liquid chromatography tandem mass spectrometry. A nine-compartment PBPK model was built using MATLAB to represent the triphasic study nature (insufficient, replenishing, and sufficient). The stimulatory and inhibitory effect of 1,25(OH)2D3 were incorporated by fold-changes in the primary metabolic enzymes CYP27B1 and CYP24A1, respectively. Incorporation of dynamic adipose partition coefficients for vitamin D3 and 25(OH)D3 and variable enzymatic reactions aided in model fitting. Measures of model predictions agreed well with data from metabolites, with 97%, 88%, and 98% of the data for 25(OH)D3, 24,25(OH)2D3, and 1,25(OH)2D3, respectively, within twofold of unity (fold error values between 0.5 and 2.0). Bootstrapping was performed and optimized parameters were reported with 95% confidence intervals. This PBPK model could be a useful tool for understanding the connections between vitamin D and its metabolites under a variety of clinical situations. SIGNIFICANCE STATEMENT: This study developed a physiologically based pharmacokinetic (PBPK) model of vitamin D3 and metabolites for patients moving from an insufficient to a repleted state over a period of 16 weeks.
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Affiliation(s)
- Colton W Sawyer
- Department of Mathematics, Southern New Hampshire University, Manchester, New Hampshire (C.W.S.); Skaggs School of Pharmacy and Pharmaceutical Sciences, University of Colorado, Aurora, Colorado (S.M.T., M.S.J.); and University of Pittsburgh, School of Pharmacy, Department of Pharmacy and Therapeutics, Pittsburgh Pennsylvania (R.E.W., T.D.N.)
| | - Stacey M Tuey
- Department of Mathematics, Southern New Hampshire University, Manchester, New Hampshire (C.W.S.); Skaggs School of Pharmacy and Pharmaceutical Sciences, University of Colorado, Aurora, Colorado (S.M.T., M.S.J.); and University of Pittsburgh, School of Pharmacy, Department of Pharmacy and Therapeutics, Pittsburgh Pennsylvania (R.E.W., T.D.N.)
| | - Raymond E West
- Department of Mathematics, Southern New Hampshire University, Manchester, New Hampshire (C.W.S.); Skaggs School of Pharmacy and Pharmaceutical Sciences, University of Colorado, Aurora, Colorado (S.M.T., M.S.J.); and University of Pittsburgh, School of Pharmacy, Department of Pharmacy and Therapeutics, Pittsburgh Pennsylvania (R.E.W., T.D.N.)
| | - Thomas D Nolin
- Department of Mathematics, Southern New Hampshire University, Manchester, New Hampshire (C.W.S.); Skaggs School of Pharmacy and Pharmaceutical Sciences, University of Colorado, Aurora, Colorado (S.M.T., M.S.J.); and University of Pittsburgh, School of Pharmacy, Department of Pharmacy and Therapeutics, Pittsburgh Pennsylvania (R.E.W., T.D.N.)
| | - Melanie S Joy
- Department of Mathematics, Southern New Hampshire University, Manchester, New Hampshire (C.W.S.); Skaggs School of Pharmacy and Pharmaceutical Sciences, University of Colorado, Aurora, Colorado (S.M.T., M.S.J.); and University of Pittsburgh, School of Pharmacy, Department of Pharmacy and Therapeutics, Pittsburgh Pennsylvania (R.E.W., T.D.N.)
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18
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Atypical kinetics of cytochrome P450 enzymes in pharmacology and toxicology. ADVANCES IN PHARMACOLOGY (SAN DIEGO, CALIF.) 2022; 95:131-176. [PMID: 35953154 DOI: 10.1016/bs.apha.2022.05.003] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Atypical kinetics are observed in metabolic reactions catalyzed by cytochrome P450 enzymes (P450). Yet, this phenomenon is regarded as experimental artifacts in some instances despite increasing evidence challenging the assumptions of typical Michaelis-Menten kinetics. As P450 play a major role in the metabolism of a wide range of substrates including drugs and endogenous compounds, it becomes critical to consider the impact of atypical kinetics on the accuracy of estimated kinetic and inhibitory parameters which could affect extrapolation of pharmacological and toxicological implications. The first half of this book chapter will focus on atypical non-Michaelis-Menten kinetics (e.g. substrate inhibition, biphasic and sigmoidal kinetics) as well as proposed underlying mechanisms supported by recent insights in mechanistic enzymology. In particular, substrate inhibition kinetics in P450 as well as concurrent drug inhibition of P450 in the presence of substrate inhibition will be further discussed. Moreover, mounting evidence has revealed that despite the high degree of sequence homology between CYP3A isoforms (i.e. CYP3A4 and CYP3A5), they have the propensities to exhibit vastly different susceptibilities and potencies of mechanism-based inactivation (MBI) with a common drug inhibitor. These experimental observations pertaining to the presence of these atypical isoform- and probe substrate-specific complexities in CYP3A isoforms by several clinically-relevant drugs will therefore be expounded and elaborated upon in the second half of this book chapter.
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19
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In vitro-in vivo correlation of the chiral pesticide prothioconazole after interaction with human CYP450 enzymes. Food Chem Toxicol 2022; 163:112947. [DOI: 10.1016/j.fct.2022.112947] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/11/2021] [Revised: 03/11/2022] [Accepted: 03/17/2022] [Indexed: 11/21/2022]
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20
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Heme peroxidases are responsible for the dehydrogenation and oxidation metabolism of harmaline into harmine. Chin J Nat Med 2022; 20:194-201. [DOI: 10.1016/s1875-5364(22)60151-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/23/2021] [Indexed: 11/19/2022]
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21
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Zheng Y, Zhang H, Liu M, Li G, Ma S, Zhang Z, Lin H, Zhan Y, Chen Z, Zhong D, Miao L, Diao X. Pharmacokinetics, Mass Balance, and Metabolism of the Novel URAT1 Inhibitor [14C]HR011303 in Humans: Metabolism is Mediated Predominantly by UDP-glucuronosyltransferase. Drug Metab Dispos 2021; 50:798-808. [PMID: 34862252 DOI: 10.1124/dmd.121.000581] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/14/2021] [Accepted: 11/30/2021] [Indexed: 11/22/2022] Open
Abstract
HR011303, a promising selective URAT1 inhibitor, is currently being studied in a phase Ⅲ clinical trial in China for the treatment of hyperuricemia and gout. In the current study, the pharmacokinetics, mass balance, and metabolism of HR011303 were examined in six healthy Chinese male subjects who received a single oral dose of 10 mg of [14C]HR011303 (80 µCi). The results showed that HR011303 was rapidly absorbed with a median T max = 1.50 h post-dose, and the arithmetic mean t 1/2 of total radioactivity was approximately 24.2 h in plasma. The mean blood-to-plasma radioactivity concentration ratio was 0.66, suggesting the preferential distribution of drug-related components in plasma. At 216 h post-dose, the mean cumulative excreted radioactivity was 91.75% of the dose, including 81.50% in urine and 10.26% in feces. Six metabolites were identified, and the parent drug HR011303 was the most abundant component in plasma and feces, but a minor component in urine. Glucuronidation of the carboxylic acid moiety of HR011303 was the primary metabolic pathway in humans, amounting to 69.63% of the dose (M5, 51.57% of the dose; M5/2, 18.06% of the dose) in the urine; however, it was not detected in plasma. UGT2B7 was responsible for the formation of M5. Overall, after a single oral dose of 10 mg of [14C]HR011303 (80 µCi), HR011303 and its main metabolites were eliminated via renal excretion. The major metabolic pathway was carboxylic acid glucuronidation, which was catalyzed predominantly by UGT2B7. Significance Statement This study determined the absorption and disposition of HR011303, a selective URAT1 inhibitor currently in development for the treatment of hyperuricemia and gout. This work helps to characterize the major metabolic pathways of new URAT inhibitors and identify the absorption and clearance mechanism.
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Affiliation(s)
- Yuandong Zheng
- DMPK, Shanghai Institute of Materia Medica, Chinese Academy of Sciences, China
| | - Hua Zhang
- First Affiliated Hospital of Soochow University, China
| | - Mengling Liu
- Shanghai Institute of Materia Medica, Chinese Academy of Sciences, China
| | - Guangze Li
- Jiangsu Hengrui Medicine Co. Ltd., China
| | - Sheng Ma
- First Affiliated Hospital of Soochow University, China
| | - Zhe Zhang
- Jiangsu Hengrui Medicine Co. Ltd, China
| | | | - Yan Zhan
- Shanghai Center for Drug Metabolism and Pharmacokinetics, Shanghai Institute of Materia Medica, Chinese Academy of Sciences, China
| | - Zhendong Chen
- Shanghai Institute of Materia Medica, Chinese Academy of Sciences, China
| | - Dafang Zhong
- Center for Drug Metabolism and Pharmacokinet, China
| | - Liyan Miao
- Department of Pharmacy, The First Affiliated Hospital of Soochow Universit, China
| | - Xingxing Diao
- DMPK, Shanghai Institute of Materia Medica, Chinese Academy of Sciences, China
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Hernandez‐Jerez AF, Adriaanse P, Aldrich A, Berny P, Coja T, Duquesne S, Focks A, Marinovich M, Millet M, Pelkonen O, Pieper S, Tiktak A, Topping CJ, Widenfalk A, Wilks M, Wolterink G, Gundert‐Remy U, Louisse J, Rudaz S, Testai E, Lostia A, Dorne J, Parra Morte JM. Scientific Opinion of the Scientific Panel on Plant Protection Products and their Residues (PPR Panel) on testing and interpretation of comparative in vitro metabolism studies. EFSA J 2021; 19:e06970. [PMID: 34987623 PMCID: PMC8696562 DOI: 10.2903/j.efsa.2021.6970] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022] Open
Abstract
EFSA asked the Panel on Plant Protection Products and their residues to deliver a Scientific Opinion on testing and interpretation of comparative in vitro metabolism studies for both new active substances and existing ones. The main aim of comparative in vitro metabolism studies of pesticide active substances is to evaluate whether all significant metabolites formed in the human in vitro test system, as a surrogate of the in vivo situation, are also present at comparable level in animal species tested in toxicological studies and, therefore, if their potential toxicity has been appropriately covered by animal studies. The studies may also help to decide which animal model, with regard to a particular compound, is the most relevant for humans. In the experimental strategy, primary hepatocytes in suspension or culture are recommended since hepatocytes are considered the most representative in vitro system for prediction of in vivo metabolites. The experimental design of 3 × 3 × 3 (concentrations, time points, technical replicates, on pooled hepatocytes) will maximise the chance to identify unique (UHM) and disproportionate (DHM) human metabolites. When DHM and UHM are being assessed, test item-related radioactivity recovery and metabolite profile are the most important parameters. Subsequently, structural characterisation of the assigned metabolites is performed with appropriate analytical techniques. In toxicological assessment of metabolites, the uncertainty factor approach is the first alternative to testing option, followed by new approach methodologies (QSAR, read-across, in vitro methods), and only if these fail, in vivo animal toxicity studies may be performed. Knowledge of in vitro metabolites in human and animal hepatocytes would enable toxicological evaluation of all metabolites of concern, and, furthermore, add useful pieces of information for detection and evaluation of metabolites in different matrices (crops, livestock, environment), improve biomonitoring efforts via better toxicokinetic understanding, and ultimately, develop regulatory schemes employing physiologically based or physiology-mimicking in silico and/or in vitro test systems to anticipate the exposure of humans to potentially hazardous substances in plant protection products.
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Ramsden D, Perloff ES, Whitcher-Johnstone A, Ho T, Patel R, Kozminski KD, Fullenwider CL, Zhang JG. Predictive In Vitro-In Vivo Extrapolation for Time Dependent Inhibition of CYP1A2, CYP2C8, CYP2C9, CYP2C19 and CYP2D6 Using Pooled Human Hepatocytes, Human Liver Microsomes, and a Simple Mechanistic Static Model. Drug Metab Dispos 2021; 50:114-127. [PMID: 34789487 DOI: 10.1124/dmd.121.000718] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/07/2021] [Accepted: 11/12/2021] [Indexed: 11/22/2022] Open
Abstract
Inactivation of Cytochrome P450 (CYP450) enzymes can lead to significant increases in exposure of co-medicants. The majority of reported in vitro to in vivo extrapolation (IVIVE) data have historically focused on CYP3A4 leaving the assessment of other CYP isoforms insubstantial. To this end, the utility of human hepatocytes (HHEP) and microsome (HLM) to predict clinically relevant DDIs was investigated with a focus on CYP1A2, CYP2C8, CYP2C9, CYP2C19 and CYP2D6. Evaluation of IVIVE for CYP2B6 was limited to only weak inhibition. A search of the University of Washington Drug-Drug Interaction Database was conducted to identify a clinically relevant weak, moderate and strong inhibitor for selective substrates of CYP1A2, CYP2C8, CYP2C9, CYP2C19 and CYP2D6, resulting in 18 inhibitors for in vitro characterization against 119 clinical interaction studies. Pooled human hepatocytes and HLM were pre-incubated with increasing concentrations of inhibitors for designated timepoints. Time dependent inhibition (TDI) was detected in HLM for four moderate/strong inhibitors suggesting that some optimization of incubation conditions (i.e. lower protein concentrations) is needed to capture weak inhibition. Clinical risk assessment was conducted by incorporating the in vitro derived kinetic parameters kinact and KI into static equations recommended by regulatory authorities. Significant overprediction was observed when applying the basic models recommended by regulatory agencies. Mechanistic static models (MSM), which consider the fraction of metabolism through the impacted enzyme, using the unbound hepatic inlet concentration lead to the best overall prediction accuracy with 92% and 85% of data from HHEPs and HLM, respectively, within 2-fold of the observed value. Significance Statement Collectively, the data demonstrate that coupling time-dependent inactivation parameters derived from pooled human hepatocytes and HLM with a mechanistic static model provides an easy and quantitatively accurate means to determine clinical DDI risk from in vitro data. Weak and moderate inhibitors did not show TDI under standard incubation conditions using HLM and optimization of incubation conditions is warranted. Recommendations are made with respect to input parameters for IVIVE of TDI with non-CYP3A enzymes using available data from HLM and HHEPs.
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Affiliation(s)
| | - Elke S Perloff
- Corning Gentest Contract Research Services, United States
| | | | - Thuy Ho
- Corning Gentest Contract Research Services, United States
| | - Reena Patel
- Corning Gentest Contract Research Services, United States
| | - Kirk D Kozminski
- Global Drug Metabolism and Pharmacokinetics, Takeda Pharmaceuticals Limited, United States
| | | | - J George Zhang
- Corning Gentest Contract Research Services, United States
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24
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Saganuwan SA. Application of modified Michaelis - Menten equations for determination of enzyme inducing and inhibiting drugs. BMC Pharmacol Toxicol 2021; 22:57. [PMID: 34635182 PMCID: PMC8507113 DOI: 10.1186/s40360-021-00521-x] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/14/2020] [Accepted: 09/06/2021] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND Pharmacokinetics (PK) is the process of absorption, distribution, metabolism and elimination (ADME) of drugs. Some drugs undergo zero-order kinetics (ethyl alcohol), first order kinetics (piroxicam) and mixed order kinetics (ascorbic acid). Drugs that undergo Michaelis-Menten metabolism are characterized by either increased or decreased metabolism constant (Km) and maximum velocity (Vmax) of enzyme reaction. Hence literatures were searched with a view to translating in vitro-in vivo enzyme kinetics to pharmacokinetic/pharmacodynamic parameters for determination of enzyme inducing and inhibiting drugs, in order to achieve optimal clinical efficacy and safety. METHODS A narrative review of retrospective secondary data on drugs, their metabolites, Vmax and Km, generated in the laboratory and clinical environments was adopted, using inclusion and exclusion criteria. Key word search strategy was applied, to assess databases of published articles on enzyme inducing and inhibiting drugs, that obey Michaelis-Menten kinetics. In vitro and in vivo kinetic parameters, such as concentration of substrate, rate of endogenous substrate production, cellular metabolic rate, initial velocity of metabolism, intrinsic clearance, percent saturation and unsaturation of the enzyme substrate, were calculated using original and modified formulas. Years and numbers of searched publications, types of equations and their applications were recorded. RESULTS A total of fifty-six formulas both established and modified were applied in the present study. Findings have shown that theophylline, voriconazole, phenytoin, thiopental, fluorouracil, thyamine and thymidine are enzyme inducers whereas, mibefradil, metronidazole, isoniazid and puromicin are enzyme inhibitors. They are metabolized and eliminated according to Michaelis-Menten principle. The order could be mixed but may change to zero or first order, depending on drug concentration, frequency and route of drug administration. CONCLUSION Hence, pharmacokinetic-pharmacodynamic translation can be optimally achieved by incorporating, newly modified Michaelis-Menten equations into pharmacokinetic formulas for clinical efficacy and safety of the enzyme inducing and inhibiting therapeutic agents used in laboratory and clinical settings.
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Affiliation(s)
- Saganuwan Alhaji Saganuwan
- Department of Veterinary Pharmacology and Toxicology, College of Veterinary Medicine, Federal University of Agriculture, P.M.B.2373, Makurdi, Benue State, Nigeria.
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25
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Numerical Methods for Modeling Enzyme Kinetics. Methods Mol Biol 2021; 2342:147-168. [PMID: 34272694 DOI: 10.1007/978-1-0716-1554-6_6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/28/2023]
Abstract
Differential equations are used to describe time-dependent changes in enzyme kinetics and pharmacokinetics. Analytical and numerical methods can be used to solve differential equations. This chapter describes the use of numerical methods in solving differential equations and its applications in characterizing the complexities observed in enzyme kinetics. A discussion is included on the use of numerical methods to overcome limitations of explicit equations in the analysis of metabolism kinetics, reversible inhibition kinetics, and inactivation kinetics. The chapter describes the advantages of using numerical methods when Michaelis-Menten assumptions do not hold.
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26
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Leow JWH, Verma RK, Lim ABH, Fan H, Chan ECY. Atypical kinetics of cytochrome P450 2J2: Epoxidation of arachidonic acid and reversible inhibition by xenobiotic inhibitors. Eur J Pharm Sci 2021; 164:105889. [PMID: 34044117 DOI: 10.1016/j.ejps.2021.105889] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/18/2021] [Revised: 05/04/2021] [Accepted: 05/20/2021] [Indexed: 01/08/2023]
Abstract
Extrahepatic CYP2J2 metabolism of arachidonic acid (AA) to bioactive regioisomeric epoxyeicosatrienoic acids (EETs) is implicated in both physiological and pathological conditions. Here, we aimed to characterize atypical substrate inhibition kinetics of this endogenous metabolic pathway and its reversible inhibition by xenobiotic inhibitors when AA is used as the physiologically-relevant substrate vis-à-vis conventional probe substrate astemizole (AST). As compared to typical Michaelis-Menten kinetics observed for AST, complete substrate inhibition was observed for CYP2J2 metabolism of AA to 14,15-EET whereby velocity of the reaction declined significantly at concentrations of AA above 20-30 µM with an estimated substrate inhibition constant (Ks) of 31 µM. In silico sequential docking of two AA substrates to orthosteric (OBS) and adjacent secondary binding sites (SBS) within a 3-dimensional homology model of CYP2J2 revealed favorable and comparable binding poses of glide-scores -3.1 and -3.8 respectively. Molecular dynamics (MD) simulations ascertained CYP2J2 conformational stability with dual AA substrate binding as time-dependent root mean squared deviation (RMSD) of protein Cα atoms and ligand heavy atoms stabilized to a plateau in all but one trajectory (n=6). The distance between heme-iron and ω6 (C14, C15) double bond of AA in OBS also increased from 7.5 ± 1.4 Å to 8.5 ± 1.8 Å when CYP2J2 was simulated with only AA in OBS versus the presence of AA in both OBS and SBS (p<0.001), supporting the observed in vitro substrate inhibition phenomenon. Poor correlation was observed between inhibitory constants (Ki) determined for a panel of nine competitive and mixed mode xenobiotic inhibitors against CYP2J2 metabolism of AA as compared to AST, whereby 4 out of 9 drugs had a greater than 5-fold difference between Ki values. Nonlinear Eadie-Hofstee plots illustrated that complete substrate inhibition of CYP2J2 by AA was not attenuated even at high concentrations of xenobiotic inhibitors which further corroborates that CYP2J2 may accommodate three or more ligands simultaneously. In light of the atypical kinetics, our results highlight the importance of using physiologically-relevant substrates in in vitro enzymatic inhibition assays for the characterization of xenobiotic-endobiotic interactions which is applicable to other complex endogenous metabolic pathways beyond CYP2J2 metabolism of AA to EETs. The accurate determination of Ki would further facilitate the association of xenobiotic-endobiotic interactions to observed therapeutic or toxic outcomes.
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Affiliation(s)
- Jacqueline Wen Hui Leow
- Department of Pharmacy, Faculty of Science, National University of Singapore, 18 Science Drive 4, Singapore 117543
| | - Ravi Kumar Verma
- Bioinformatics Institute (BII), Agency for Science, Technology and Research (A*STAR), 30 Biopolis Street, #07-01 Matrix, Singapore 138671
| | - Amos Boon Hao Lim
- Department of Pharmacy, Faculty of Science, National University of Singapore, 18 Science Drive 4, Singapore 117543
| | - Hao Fan
- Bioinformatics Institute (BII), Agency for Science, Technology and Research (A*STAR), 30 Biopolis Street, #07-01 Matrix, Singapore 138671
| | - Eric Chun Yong Chan
- Department of Pharmacy, Faculty of Science, National University of Singapore, 18 Science Drive 4, Singapore 117543.
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27
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Liu Q, Ou-Yang QG, Lin QM, Lu XR, Ma YQ, Li YH, Xu RA, Lin DD, Hu GX, Cai JP. Effects of 27 CYP3A4 protein variants on saxagliptin metabolism in vitro. Fundam Clin Pharmacol 2021; 36:150-159. [PMID: 33961299 DOI: 10.1111/fcp.12693] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2021] [Accepted: 04/27/2021] [Indexed: 12/20/2022]
Abstract
Saxagliptin is a dipeptidyl peptidase 4 (DPP-4) inhibitor widely used in patients with type 2 diabetes. It can increase the amount of insulin after meals and lower blood sugar. CYP450 3A4 (CYP3A4) can metabolize about 30%-40% of therapeutic drugs. Individual differences caused by CYP3A4 genetic polymorphisms can lead to treatment failure, unpredictable side effects, or severe drug toxicity. The aim of this study was to evaluate the catalytic activities of 27 CYP3A4 variants on saxagliptin metabolism in vitro, which were identified in human CYP alleles. We successfully constructed 27 kinds of wild-type and variant vectors of pFast-dual-OR-3A4 by overlap extension PCR and prepared 27 kinds of CYP3A4 highly expressed cell microsomes by baculovirus insect cell expression system. The ultra-performance liquid chromatography tandem mass spectrometry (UPLC-MS/MS) was used to detect the concentrations of the metabolite of saxagliptin (5-hydroxysaxagliptin) and the internal standard. Compared with the wild-type CYP3A4.1, the intrinsic clearance values of most varieties decreased to 1.91%-77.08%. Most of these varieties showed a decrease in Vmax and an increase in Km values compared with wild type. We are the first to report the vitro metabolic data of 27 CYP3A4 variants of the metabolism of saxagliptin which can deepen our understanding of individualized drug use by combining previous studies about the effects of CYP3A4 variants of drug metabolism. With further in vivo studies, we hope it can guide individualized drug use in the clinic when the variants with low metabolic activity to saxagliptin were sequenced in the human body.
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Affiliation(s)
- Qian Liu
- Chinese Academy of Medical Sciences, Peking Union Medical College, Beijing, China.,The Key Laboratory of Geriatrics, Beijing Institute of Geriatrics, Beijing Hospital, National Center of Gerontology, National Health Commission, Institute of Geriatric Medicine, Chinese Academy of Medical Sciences, Beijing, China
| | - Qiu-Geng Ou-Yang
- School of Pharmacy, Wenzhou Medical University, Wenzhou, Zhejiang, China
| | - Qian-Meng Lin
- Department of Oncology, NHC Key Laboratory of Cancer Proteomics, XiangYa Hospital, Central South University, Changsha, China
| | - Xiang-Ran Lu
- School of Pharmacy, Wenzhou Medical University, Wenzhou, Zhejiang, China
| | - Ya-Qing Ma
- The Key Laboratory of Geriatrics, Beijing Institute of Geriatrics, Beijing Hospital, National Center of Gerontology, National Health Commission, Institute of Geriatric Medicine, Chinese Academy of Medical Sciences, Beijing, China
| | - Ying-Hui Li
- School of Pharmacy, Wenzhou Medical University, Wenzhou, Zhejiang, China
| | - Ren-Ai Xu
- Department of Pharmacy, The First Affiliated Hospital of Wenzhou Medical University, Wenzhou, Zhejiang, China
| | - Dong-Dong Lin
- School of Pharmacy, Wenzhou Medical University, Wenzhou, Zhejiang, China
| | - Guo-Xin Hu
- School of Pharmacy, Wenzhou Medical University, Wenzhou, Zhejiang, China
| | - Jian-Ping Cai
- Chinese Academy of Medical Sciences, Peking Union Medical College, Beijing, China.,The Key Laboratory of Geriatrics, Beijing Institute of Geriatrics, Beijing Hospital, National Center of Gerontology, National Health Commission, Institute of Geriatric Medicine, Chinese Academy of Medical Sciences, Beijing, China
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28
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Analytical Determination of the Optimal Feed Temperature for Hydrogen Peroxide Decomposition Process Occurring in Bioreactor with a Fixed-Bed of Commercial Catalase. Catalysts 2020. [DOI: 10.3390/catal11010035] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022] Open
Abstract
The hydrogen peroxide-immobilized commercial catalase system was chosen to estimate the optimal feed temperature (OFT) for fixed-bed reactor (FXBR). This feed temperature was obtained based on analytical solution by maximizing the time-averaged substrate conversion under a constant feed flow rate and temperature constraints. In calculations a set of partial differential equations describing the conservation equation for fixed-bed reactor, assuming plug flow and kinetic equation for the rate of enzyme parallel deactivation was taken into account. The model is based on kinetic, and mass-transfer parameters estimated previously in a real decomposition process of hydrogen peroxide (HP). The simulation showed that the OFT is strongly dependent on hydrogen peroxide feed concentration, feed flow rate and diffusional resistances expressed by biocatalyst global effectiveness factor. It has been shown that the more significant diffusional resistances and the higher HP conversions are, the higher the optimal feed temperature is. The calculated values of the OFT were verified with the experimental results obtained in the model reactor at selected values of the feed flow rate. Presented analysis poses a significant simplification in a numerical computational procedure and can be very useful for engineers to select the temperature condition at which bioreactor productivity is expected to be maximal.
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29
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Miners JO, Rowland A, Novak JJ, Lapham K, Goosen TC. Evidence-based strategies for the characterisation of human drug and chemical glucuronidation in vitro and UDP-glucuronosyltransferase reaction phenotyping. Pharmacol Ther 2020; 218:107689. [PMID: 32980440 DOI: 10.1016/j.pharmthera.2020.107689] [Citation(s) in RCA: 22] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/04/2020] [Revised: 09/17/2020] [Accepted: 09/18/2020] [Indexed: 12/26/2022]
Abstract
Enzymes of the UDP-glucuronosyltransferase (UGT) superfamily contribute to the elimination of drugs from almost all therapeutic classes. Awareness of the importance of glucuronidation as a drug clearance mechanism along with increased knowledge of the enzymology of drug and chemical metabolism has stimulated interest in the development and application of approaches for the characterisation of human drug glucuronidation in vitro, in particular reaction phenotyping (the fractional contribution of the individual UGT enzymes responsible for the glucuronidation of a given drug), assessment of metabolic stability, and UGT enzyme inhibition by drugs and other xenobiotics. In turn, this has permitted the implementation of in vitro - in vivo extrapolation approaches for the prediction of drug metabolic clearance, intestinal availability, and drug-drug interaction liability, all of which are of considerable importance in pre-clinical drug development. Indeed, regulatory agencies (FDA and EMA) require UGT reaction phenotyping for new chemical entities if glucuronidation accounts for ≥25% of total metabolism. In vitro studies are most commonly performed with recombinant UGT enzymes and human liver microsomes (HLM) as the enzyme sources. Despite the widespread use of in vitro approaches for the characterisation of drug and chemical glucuronidation by HLM and recombinant enzymes, evidence-based guidelines relating to experimental approaches are lacking. Here we present evidence-based strategies for the characterisation of drug and chemical glucuronidation in vitro, and for UGT reaction phenotyping. We anticipate that the strategies will inform practice, encourage development of standardised experimental procedures where feasible, and guide ongoing research in the field.
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Affiliation(s)
- John O Miners
- Department of Clinical Pharmacology and Flinders Centre for Innovation in Cancer, College of Medicine and Public Health, Flinders University, Adelaide, Australia.
| | - Andrew Rowland
- Department of Clinical Pharmacology and Flinders Centre for Innovation in Cancer, College of Medicine and Public Health, Flinders University, Adelaide, Australia
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30
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Sun G, Hu C, Mei Q, Luo M, Chen X, Li Z, Liu Y, Deng Z, Zhang Z, Sun Y. Uncovering the cytochrome P450-catalyzed methylenedioxy bridge formation in streptovaricins biosynthesis. Nat Commun 2020; 11:4501. [PMID: 32908132 PMCID: PMC7481197 DOI: 10.1038/s41467-020-18336-5] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/26/2020] [Accepted: 08/18/2020] [Indexed: 12/14/2022] Open
Abstract
Streptovaricin C is a naphthalenic ansamycin antibiotic structurally similar to rifamycins with potential anti-MRSA bioactivities. However, the formation mechanism of the most fascinating and bioactivity-related methylenedioxy bridge (MDB) moiety in streptovaricins is unclear. Based on genetic and biochemical evidences, we herein clarify that the P450 enzyme StvP2 catalyzes the MDB formation in streptovaricins, with an atypical substrate inhibition kinetics. Furthermore, X-ray crystal structures in complex with substrate and structure-based mutagenesis reveal the intrinsic details of the enzymatic reaction. The mechanism of MDB formation is proposed to be an intramolecular nucleophilic substitution resulting from the hydroxylation by the heme core and the keto-enol tautomerization via a crucial catalytic triad (Asp89-His92-Arg72) in StvP2. In addition, in vitro reconstitution uncovers that C6-O-methylation and C4-O-acetylation of streptovaricins are necessary prerequisites for the MDB formation. This work provides insight for the MDB formation and adds evidence in support of the functional versatility of P450 enzymes. Streptovaricin C is an antibiotic containing a methylenedioxy bridge (MDB) moiety essential for its activity. Here, the authors show that a P450 monooxygenase StvP2 catalyses MDB formation, report its crystal structure in complex with the substrate, and elucidate mechanistic details of MDB formation.
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Affiliation(s)
- Guo Sun
- Key Laboratory of Combinatorial Biosynthesis and Drug Discovery, Ministry of Education, Wuhan University School of Pharmaceutical Sciences, 430071, Wuhan, P. R. China
| | - Chaoqun Hu
- Key Laboratory of Combinatorial Biosynthesis and Drug Discovery, Ministry of Education, Wuhan University School of Pharmaceutical Sciences, 430071, Wuhan, P. R. China
| | - Qing Mei
- Key Laboratory of Combinatorial Biosynthesis and Drug Discovery, Ministry of Education, Wuhan University School of Pharmaceutical Sciences, 430071, Wuhan, P. R. China
| | - Minghe Luo
- Key Laboratory of Combinatorial Biosynthesis and Drug Discovery, Ministry of Education, Wuhan University School of Pharmaceutical Sciences, 430071, Wuhan, P. R. China
| | - Xu Chen
- Key Laboratory of Combinatorial Biosynthesis and Drug Discovery, Ministry of Education, Wuhan University School of Pharmaceutical Sciences, 430071, Wuhan, P. R. China
| | - Zhengyuan Li
- Key Laboratory of Combinatorial Biosynthesis and Drug Discovery, Ministry of Education, Wuhan University School of Pharmaceutical Sciences, 430071, Wuhan, P. R. China
| | - Yuanzhen Liu
- Key Laboratory of Combinatorial Biosynthesis and Drug Discovery, Ministry of Education, Wuhan University School of Pharmaceutical Sciences, 430071, Wuhan, P. R. China
| | - Zixin Deng
- Key Laboratory of Combinatorial Biosynthesis and Drug Discovery, Ministry of Education, Wuhan University School of Pharmaceutical Sciences, 430071, Wuhan, P. R. China
| | - Zhengyu Zhang
- Key Laboratory of Combinatorial Biosynthesis and Drug Discovery, Ministry of Education, Wuhan University School of Pharmaceutical Sciences, 430071, Wuhan, P. R. China.
| | - Yuhui Sun
- Key Laboratory of Combinatorial Biosynthesis and Drug Discovery, Ministry of Education, Wuhan University School of Pharmaceutical Sciences, 430071, Wuhan, P. R. China.
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31
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Espiritu MJ, Chen J, Yadav J, Larkin M, Pelletier RD, Chan JM, Gc JB, Natesan S, Harrelson JP. Mechanisms of Herb-Drug Interactions Involving Cinnamon and CYP2A6: Focus on Time-Dependent Inhibition by Cinnamaldehyde and 2-Methoxycinnamaldehyde. Drug Metab Dispos 2020; 48:1028-1043. [PMID: 32788161 DOI: 10.1124/dmd.120.000087] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/07/2020] [Accepted: 07/15/2020] [Indexed: 12/21/2022] Open
Abstract
Information is scarce regarding pharmacokinetic-based herb-drug interactions (HDI) with trans-cinnamaldehyde (CA) and 2-methoxycinnamaldehyde (MCA), components of cinnamon. Given the presence of cinnamon in food and herbal treatments for various diseases, HDIs involving the CYP2A6 substrates nicotine and letrozole with MCA (KS = 1.58 µM; Hill slope = 1.16) and CA were investigated. The time-dependent inhibition (TDI) by MCA and CA of CYP2A6-mediated nicotine metabolism is a complex process involving multiple mechanisms. Molecular dynamic simulations showed that CYP2A6's active site accommodates two dynamic ligands. The preferred binding orientations for MCA and CA were consistent with the observed metabolism: epoxidation, O-demethylation, and aromatic hydroxylation of MCA and cinnamic acid formation from CA. The percent remaining activity plots for TDI by MCA and CA were curved, and they were analyzed with a numerical method using models of varying complexity. The best-fit models support multiple inactivator binding, inhibitor depletion, and partial inactivation. Deconvoluted mass spectra indicated that MCA and CA modified CYP2A6 apoprotein with mass additions of 156.79 (142.54-171.04) and 132.67 (123.37-141.98), respectively, and it was unaffected by glutathione. Heme degradation was observed in the presence of MCA (48.5% ± 13.4% loss; detected by liquid chromatography-tandem mass spectrometry). In the absence of clinical data, HDI predictions were made for nicotine and letrozole using inhibition parameters from the best-fit TDI models and parameters scaled from rats. Predicted area under the concentration-time curve fold changes were 4.29 (CA-nicotine), 4.92 (CA-letrozole), 4.35 (MCA-nicotine), and 5.00 (MCA-letrozole). These findings suggest that extensive exposure to cinnamon (corresponding to ≈ 275 mg CA) would lead to noteworthy interactions. SIGNIFICANCE STATEMENT: Human exposure to cinnamon is common because of its presence in food and cinnamon-based herbal treatments. Little is known about the risk for cinnamaldehyde and methoxycinnamaldehyde, two components of cinnamon, to interact with drugs that are eliminated by CYP2A6-mediated metabolism. The interactions with CYP2A6 are complex, involving multiple-ligand binding, time-dependent inhibition of nicotine metabolism, heme degradation, and apoprotein modification. An herb-drug interaction prediction suggests that extensive exposure to cinnamon would lead to noteworthy interactions with nicotine.
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Affiliation(s)
- Michael J Espiritu
- School of Pharmacy, Pacific University Oregon, Hillsboro, Oregon (M.J.E., M.L., J.P.H.); College of Pharmacy and Pharmaceutical Sciences, Washington State University, Spokane, Washington (J.C., J.B.G., S.N.); Amgen, Cambridge, Massachusetts (J.Y.); Department of Medicinal Chemistry, University of Washington, Seattle, Washington (R.D.P.); and Chemistry Department, Pacific University Oregon, Forest Grove, Oregon (J.M.C.)
| | - Justin Chen
- School of Pharmacy, Pacific University Oregon, Hillsboro, Oregon (M.J.E., M.L., J.P.H.); College of Pharmacy and Pharmaceutical Sciences, Washington State University, Spokane, Washington (J.C., J.B.G., S.N.); Amgen, Cambridge, Massachusetts (J.Y.); Department of Medicinal Chemistry, University of Washington, Seattle, Washington (R.D.P.); and Chemistry Department, Pacific University Oregon, Forest Grove, Oregon (J.M.C.)
| | - Jaydeep Yadav
- School of Pharmacy, Pacific University Oregon, Hillsboro, Oregon (M.J.E., M.L., J.P.H.); College of Pharmacy and Pharmaceutical Sciences, Washington State University, Spokane, Washington (J.C., J.B.G., S.N.); Amgen, Cambridge, Massachusetts (J.Y.); Department of Medicinal Chemistry, University of Washington, Seattle, Washington (R.D.P.); and Chemistry Department, Pacific University Oregon, Forest Grove, Oregon (J.M.C.)
| | - Michael Larkin
- School of Pharmacy, Pacific University Oregon, Hillsboro, Oregon (M.J.E., M.L., J.P.H.); College of Pharmacy and Pharmaceutical Sciences, Washington State University, Spokane, Washington (J.C., J.B.G., S.N.); Amgen, Cambridge, Massachusetts (J.Y.); Department of Medicinal Chemistry, University of Washington, Seattle, Washington (R.D.P.); and Chemistry Department, Pacific University Oregon, Forest Grove, Oregon (J.M.C.)
| | - Robert D Pelletier
- School of Pharmacy, Pacific University Oregon, Hillsboro, Oregon (M.J.E., M.L., J.P.H.); College of Pharmacy and Pharmaceutical Sciences, Washington State University, Spokane, Washington (J.C., J.B.G., S.N.); Amgen, Cambridge, Massachusetts (J.Y.); Department of Medicinal Chemistry, University of Washington, Seattle, Washington (R.D.P.); and Chemistry Department, Pacific University Oregon, Forest Grove, Oregon (J.M.C.)
| | - Jeannine M Chan
- School of Pharmacy, Pacific University Oregon, Hillsboro, Oregon (M.J.E., M.L., J.P.H.); College of Pharmacy and Pharmaceutical Sciences, Washington State University, Spokane, Washington (J.C., J.B.G., S.N.); Amgen, Cambridge, Massachusetts (J.Y.); Department of Medicinal Chemistry, University of Washington, Seattle, Washington (R.D.P.); and Chemistry Department, Pacific University Oregon, Forest Grove, Oregon (J.M.C.)
| | - Jeevan B Gc
- School of Pharmacy, Pacific University Oregon, Hillsboro, Oregon (M.J.E., M.L., J.P.H.); College of Pharmacy and Pharmaceutical Sciences, Washington State University, Spokane, Washington (J.C., J.B.G., S.N.); Amgen, Cambridge, Massachusetts (J.Y.); Department of Medicinal Chemistry, University of Washington, Seattle, Washington (R.D.P.); and Chemistry Department, Pacific University Oregon, Forest Grove, Oregon (J.M.C.)
| | - Senthil Natesan
- School of Pharmacy, Pacific University Oregon, Hillsboro, Oregon (M.J.E., M.L., J.P.H.); College of Pharmacy and Pharmaceutical Sciences, Washington State University, Spokane, Washington (J.C., J.B.G., S.N.); Amgen, Cambridge, Massachusetts (J.Y.); Department of Medicinal Chemistry, University of Washington, Seattle, Washington (R.D.P.); and Chemistry Department, Pacific University Oregon, Forest Grove, Oregon (J.M.C.)
| | - John P Harrelson
- School of Pharmacy, Pacific University Oregon, Hillsboro, Oregon (M.J.E., M.L., J.P.H.); College of Pharmacy and Pharmaceutical Sciences, Washington State University, Spokane, Washington (J.C., J.B.G., S.N.); Amgen, Cambridge, Massachusetts (J.Y.); Department of Medicinal Chemistry, University of Washington, Seattle, Washington (R.D.P.); and Chemistry Department, Pacific University Oregon, Forest Grove, Oregon (J.M.C.)
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Raunio H, Pentikäinen O, Juvonen RO. Coumarin-Based Profluorescent and Fluorescent Substrates for Determining Xenobiotic-Metabolizing Enzyme Activities In Vitro. Int J Mol Sci 2020; 21:ijms21134708. [PMID: 32630278 PMCID: PMC7369699 DOI: 10.3390/ijms21134708] [Citation(s) in RCA: 21] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/16/2020] [Revised: 06/29/2020] [Accepted: 06/30/2020] [Indexed: 01/03/2023] Open
Abstract
Activities of xenobiotic-metabolizing enzymes have been measured with various in vitro and in vivo methods, such as spectrophotometric, fluorometric, mass spectrometric, and radioactivity-based techniques. In fluorescence-based assays, the reaction produces a fluorescent product from a nonfluorescent substrate or vice versa. Fluorescence-based enzyme assays are usually highly sensitive and specific, allowing measurements on small specimens of tissues with low enzyme activities. Fluorescence assays are also amenable to miniaturization of the reaction mixtures and can thus be done in high throughput. 7-Hydroxycoumarin and its derivatives are widely used as fluorophores due to their desirable photophysical properties. They possess a large π-π conjugated system with electron-rich and charge transfer properties. This conjugated structure leads to applications of 7-hydroxycoumarins as fluorescent sensors for biological activities. We describe in this review historical highlights and current use of coumarins and their derivatives in evaluating activities of the major types of xenobiotic-metabolizing enzyme systems. Traditionally, coumarin substrates have been used to measure oxidative activities of cytochrome P450 (CYP) enzymes. For this purpose, profluorescent coumarins are very sensitive, but generally lack selectivity for individual CYP forms. With the aid of molecular modeling, we have recently described several new coumarin-based substrates for measuring activities of CYP and conjugating enzymes with improved selectivity.
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Affiliation(s)
- Hannu Raunio
- School of Pharmacy, Faculty of Health Sciences, University of Eastern Finland, 70600 Kuopio, Finland;
- Correspondence:
| | - Olli Pentikäinen
- Institute of Biomedicine, Faculty of Medicine, University of Turku, 20520 Turku, Finland;
| | - Risto O. Juvonen
- School of Pharmacy, Faculty of Health Sciences, University of Eastern Finland, 70600 Kuopio, Finland;
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Hou J, Reid NE, Tromberg BJ, Potma EO. Kinetic Analysis of Lipid Metabolism in Breast Cancer Cells via Nonlinear Optical Microscopy. Biophys J 2020; 119:258-264. [PMID: 32610090 DOI: 10.1016/j.bpj.2020.06.007] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/01/2019] [Revised: 06/01/2020] [Accepted: 06/08/2020] [Indexed: 12/26/2022] Open
Abstract
Investigating the behavior of breast cancer cells via reaction kinetics may help unravel the mechanisms that underlie metabolic changes in tumors. However, obtaining human in vivo kinetic data is challenging because of difficulties associated with measuring these parameters. Nondestructive methods of measuring lipid content in live cells provide a novel approach to quantitatively model lipid synthesis and consumption. In this study, coherent Raman scattering microscopy was used to probe de novo intracellular lipid content. Combining nonlinear optical microscopy and Michaelis-Menten kinetics-based simulations, we isolated fatty acid synthesis/consumption rates and elucidated effects of altered lipid metabolism in T47D breast cancer cells. When treated with 17β-estradiol, the lipid utilization in cancer cells jumped by twofold. Meanwhile, the rate of de novo lipid synthesis in cancer cells treated with 17β-estradiol was increased by 42%. To test the model in extreme metabolic conditions, we treated T47D cells with etomoxir. Our kinetic analysis demonstrated that the rate of key enzymatic reactions dropped by 75%. These results underline the capability to probe lipid alterations in live cells with minimum interruption and to characterize lipid metabolism in breast cancer cells via quantitative kinetic models and parameters.
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Affiliation(s)
- Jue Hou
- Beckman Laser Institute and Medical Center, University of California, Irvine, Irvine, California
| | - Nellone E Reid
- Department of Chemical and Materials Engineering, New Jersey Institute of Technology, Newark, New Jersey
| | - Bruce J Tromberg
- Beckman Laser Institute and Medical Center, University of California, Irvine, Irvine, California
| | - Eric O Potma
- Beckman Laser Institute and Medical Center, University of California, Irvine, Irvine, California.
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