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Abstract
MAO activity measurement can be monitored by direct peroxidase-free assays following different spectroscopy methods. Typically, these are assays that follow the conversion of different MAO substrates into its corresponding products monitored in either absorbance or fluorescence. Herein, we describe the assays for enzyme activity assessment with MAO B and particularly the MAO A substrate kynuramine, as well as the MAO B substrate benzylamine. Moreover, we also describe MAO activity determination using the tertiary amine substrate allyl amine 1-methyl-4-(1-methyl-1 H-pyrrol-2-yl)-1,2,3,6-tetrahydropyridine (MMTP). These are very useful methods for the investigation of MAO inhibitory activity by molecules known to be HRP-interfering. In the present chapter we demonstrate the application of these methods in MAO activity and Michaelis-Menten curve determinations as well as inhibitory activity experiments.
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Affiliation(s)
- Joana Reis
- Department of Biology and Biotechnology, University of Pavia, Pavia, Italy
| | - Claudia Binda
- Department of Biology and Biotechnology, University of Pavia, Pavia, Italy.
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2
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Brooks A, Mufarreh AJ, Shao X, Kaur T, Stauff J, Arteaga J, Kilbourn MR, Scott PJH. Improved Synthesis of [ 11C]COU and [ 11C]PHXY, Evaluation of Neurotoxicity, and Imaging of MAOs in Rodent Heart. ACS Med Chem Lett 2020; 11:2300-2304. [PMID: 33214844 PMCID: PMC7667825 DOI: 10.1021/acsmedchemlett.0c00419] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2020] [Accepted: 08/28/2020] [Indexed: 02/06/2023] Open
Abstract
The radiotracers [11C]COU and [11C]PHXY are potential PET imaging agents for in vivo studies of monoamine oxidases (MAOs), as previously shown in rodent and primate brain. One-pot, automated methods for the radiosynthesis of [11C]PHXY and [11C]COU were developed to provide reliable and improved radiochemical yields. Although derived from the structure of the neurotoxin MPTP, COU did not exhibit in vivo neurotoxicity to dopaminergic nerve terminals in the mouse brain as assayed by losses of VMAT2 radioligand binding. PET imaging studies in rats demonstrated that both [11C]COU and [11C]PHXY exhibit retention in cardiac tissues that can be blocked by pretreatment with the MAO inhibitors deprenyl (MAO-B) and pargyline (MAO-A and -B). In addition to prior neuroimaging applications, [11C]COU and [11C]PHXY are thus also of interest for studies of MAO enzymatic activity and imaging of sympathetic nerve density in heart.
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Affiliation(s)
- Allen
F. Brooks
- Department
of Radiology, University of Michigan Medical
School, Ann Arbor, Michigan 48109, United
States
| | - Anthony J. Mufarreh
- Department
of Radiology, University of Michigan Medical
School, Ann Arbor, Michigan 48109, United
States
| | - Xia Shao
- Department
of Radiology, University of Michigan Medical
School, Ann Arbor, Michigan 48109, United
States
| | - Tanpreet Kaur
- Department
of Radiology, University of Michigan Medical
School, Ann Arbor, Michigan 48109, United
States
| | - Jenelle Stauff
- Department
of Radiology, University of Michigan Medical
School, Ann Arbor, Michigan 48109, United
States
| | - Janna Arteaga
- Department
of Radiology, University of Michigan Medical
School, Ann Arbor, Michigan 48109, United
States
| | - Michael R. Kilbourn
- Department
of Radiology, University of Michigan Medical
School, Ann Arbor, Michigan 48109, United
States
| | - Peter J. H. Scott
- Department
of Radiology, University of Michigan Medical
School, Ann Arbor, Michigan 48109, United
States
- Department
of Pharmacology, University of Michigan, Ann Arbor, Michigan 48109, United States
- Interdepartmental
Program in Medicinal Chemistry, University
of Michigan, Ann Arbor, Michigan 48109, United
States
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Iacovino LG, Reis J, Mai A, Binda C, Mattevi A. Diphenylene Iodonium Is a Noncovalent MAO Inhibitor: A Biochemical and Structural Analysis. ChemMedChem 2020; 15:1394-1397. [PMID: 32459875 DOI: 10.1002/cmdc.202000264] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/23/2020] [Indexed: 12/23/2022]
Abstract
Diphenylene iodonium (DPI) is known for its inhibitory activities against many flavin- and heme-dependent enzymes, and is often used as an NADPH oxidase inhibitor. We probed the efficacy of DPI on two well-known drug targets, the human monoamine oxidases MAO A and B. UV-visible spectrophotometry and steady-state kinetics experiments demonstrate that DPI acts as a competitive and reversible MAO inhibitor with Ki values of 1.7 and 0.3 μM for MAO A and MAO B, respectively. Elucidation of the crystal structure of human MAO B bound to the inhibitor revealed that DPI binds deeply in the active-site cavity to establish multiple hydrophobic interactions with the surrounding side chains and the flavin. These data prove that DPI is a genuine MAO inhibitor and that the inhibition mechanism does not involve a reaction with the reduced flavin. This binding and inhibitory activity against the MAOs, two major reactive oxygen species (ROS)-producing enzymes, will have to be carefully considered when interpreting experiments that rely on DPI for target validation and chemical biology studies on ROS functions.
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Affiliation(s)
- Luca G Iacovino
- Department of Biology and Biotechnology "Lazzaro Spallanzani", University of Pavia, Via Ferrata 9, 27100, Pavia, Italy
| | - Joana Reis
- Department of Biology and Biotechnology "Lazzaro Spallanzani", University of Pavia, Via Ferrata 9, 27100, Pavia, Italy
| | - Antonello Mai
- Department of Drug Chemistry and Technologies, Sapienza University of Rome, P.le A. Moro 5, 00185, Rome, Italy
| | - Claudia Binda
- Department of Biology and Biotechnology "Lazzaro Spallanzani", University of Pavia, Via Ferrata 9, 27100, Pavia, Italy
| | - Andrea Mattevi
- Department of Biology and Biotechnology "Lazzaro Spallanzani", University of Pavia, Via Ferrata 9, 27100, Pavia, Italy
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Shalaby R, Petzer JP, Petzer A, Ashraf UM, Atari E, Alasmari F, Kumarasamy S, Sari Y, Khalil A. SAR and molecular mechanism studies of monoamine oxidase inhibition by selected chalcone analogs. J Enzyme Inhib Med Chem 2019; 34:863-876. [PMID: 30915862 PMCID: PMC6442233 DOI: 10.1080/14756366.2019.1593158] [Citation(s) in RCA: 29] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
The present study describes the synthesis of a series of 22 chalcone analogs. These compounds were evaluated as potential human MAO-A and MAO-B inhibitors. The compounds showed varied selectivity against the two isoforms. The IC50 values were found to be in the micromolar to submicromolar range. The Ki values of compound 16 were determined to be 0.047 and 0.020 μM for the inhibition of MAO-A and MAO-B, respectively. Dialysis of enzyme-inhibitor mixtures indicated a reversible competitive mode of inhibition. Most of the synthesized chalcone analogs showed a better selectivity toward MAO-B. However, introducing of 2,4,6-trimethoxy substituents on ring B shifted the selectivity toward MAO-A. In addition, we investigated the molecular mechanism of MAO-B inhibition by selected chalcone analogs. Our results revealed that these selected chalcone analogs increased dopamine levels in the rat hepatoma (H4IIE) cells and decreased the relative mRNA expression of the MAO-B enzyme.
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Affiliation(s)
- Raed Shalaby
- a Department of Pharmaceutical Sciences, College of Pharmacy , Qatar University , Doha , Qatar
| | - Jacobus P Petzer
- b Department of Pharmaceutical Chemistry, School of Pharmacy and Centre of Excellence for Pharmaceutical Sciences , North-West University , Potchefstroom , South Africa
| | - Anél Petzer
- b Department of Pharmaceutical Chemistry, School of Pharmacy and Centre of Excellence for Pharmaceutical Sciences , North-West University , Potchefstroom , South Africa
| | - Usman M Ashraf
- c Department of Physiology and Pharmacology , Centre for Hypertension and Personalized Medicine, University of Toledo College of Medicine , Toledo , OH , USA
| | - Ealla Atari
- c Department of Physiology and Pharmacology , Centre for Hypertension and Personalized Medicine, University of Toledo College of Medicine , Toledo , OH , USA
| | - Fawaz Alasmari
- d Department of Pharmacology and Experimental Therapeutics , College of Pharmacy and Pharmaceutical Sciences, The University of Toledo , Toledo , OH , USA
| | - Sivarajan Kumarasamy
- c Department of Physiology and Pharmacology , Centre for Hypertension and Personalized Medicine, University of Toledo College of Medicine , Toledo , OH , USA
| | - Youssef Sari
- d Department of Pharmacology and Experimental Therapeutics , College of Pharmacy and Pharmaceutical Sciences, The University of Toledo , Toledo , OH , USA
| | - Ashraf Khalil
- a Department of Pharmaceutical Sciences, College of Pharmacy , Qatar University , Doha , Qatar
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Synthesis, Structural and Thermal Studies of 3-(1-Benzyl-1,2,3,6-tetrahydropyridin-4-yl)-5-ethoxy-1 H-indole (D2AAK1_3) as Dopamine D₂ Receptor Ligand. Molecules 2018; 23:molecules23092249. [PMID: 30181442 PMCID: PMC6225423 DOI: 10.3390/molecules23092249] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/26/2018] [Revised: 08/23/2018] [Accepted: 08/31/2018] [Indexed: 11/17/2022] Open
Abstract
Compound D2AAK1_3 was designed as a modification of the lead structure D2AAK1 (an in vivo active multi-target compound with nanomolar affinity to a number of aminergic GPCRs) and synthesized in the reaction of 5-ethoxyindole and 1-benzyl-4-piperidone. This compound has an affinity to the human dopamine D₂ receptor with Ki of 151 nM. The aim of these studies was the structural and thermal characterization of the compound D2AAK1_3. In particular; X-ray studies; molecular docking and molecular dynamics as well as thermal analysis were performed. The studied compound crystallizes in orthorhombic system; in chiral space group P2₁2₁2₁. The compound has a non-planar conformation. The studied compound was docked to the novel X-ray structure of the human dopamine D₂ receptor in the inactive state (PDB ID: 6CM4) and established the main contact between its protonatable nitrogen atom and Asp (3.32) of the receptor. The obtained binding pose was stable in molecular dynamics simulations. Thermal stability of the compound was investigated using the TG-DSC technique in the air atmosphere, while TG-FTIR analyses in air and nitrogen atmospheres were also performed. The studied compound is characterized by good thermal stability. The main volatile products of combustion are the following gases: CO₂; H₂O toluene and CO while in the case of pyrolysis process in the FTIR spectra; the characteristic bands of NH₃; piperidine and indole are additionally observed.
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Design and synthesis of novel chalcones as potent selective monoamine oxidase-B inhibitors. Eur J Med Chem 2016; 114:162-9. [DOI: 10.1016/j.ejmech.2016.02.038] [Citation(s) in RCA: 67] [Impact Index Per Article: 8.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2015] [Revised: 02/13/2016] [Accepted: 02/15/2016] [Indexed: 11/20/2022]
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Brooks AF, Shao X, Quesada CA, Sherman P, Scott PJH, Kilbourn MR. In Vivo Metabolic Trapping Radiotracers for Imaging Monoamine Oxidase-A and -B Enzymatic Activity. ACS Chem Neurosci 2015; 6:1965-71. [PMID: 26393369 DOI: 10.1021/acschemneuro.5b00223] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/24/2023] Open
Abstract
The isozymes of monoamine oxidase (MAO-A and MAO-B) are important enzymes involved in the metabolism of numerous biogenic amines, including the neurotransmitters serotonin, dopamine, and norepinephrine. Recently, changes in concentrations of MAO-B have been proposed to be an in vivo marker of neuroinflammation associated with Alzheimer's disease. Previous developments of in vivo radiotracers for imaging changes in MAO enzyme expression or activity have utilized the irreversible propargylamine-based suicide inhibitors or high-affinity reversibly binding inhibitors. As an alternative approach, we have investigated 1-[(11)C]methyl-4-aryloxy-1,2,3,6-tetrahydropyridines as metabolic trapping agents for the monoamine oxidases. MAO-mediated oxidation and spontaneous hydrolysis yield 1-[(11)C]methyl-2,3-dihydro-4-pyridinone as a hydrophilic metabolite that is trapped within brain tissues. Radiotracers with phenyl, biphenyl, and 7-coumarinyl ethers were evaluated using microPET imaging in rat and primate brains. No isozyme selectivity for radiotracer trapping was observed in the rat brain for any compound, but in the monkey brain, the phenyl ether demonstrated MAO-A selectivity and the coumarinyl ether showed MAO-B selectivity. These are lead compounds for further development of 1-[(11)C]methyl-4-aryloxy-1,2,3,6-tetrahydropyridines with optimized brain pharmacokinetics and isozyme selectivity.
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Affiliation(s)
- Allen F. Brooks
- Division of Nuclear Medicine, Department
of Radiology, ‡The Interdepartmental
Program in Medicinal Chemistry, University of Michigan Medical School, Ann
Arbor, Michigan 48109, United States
| | - Xia Shao
- Division of Nuclear Medicine, Department
of Radiology, ‡The Interdepartmental
Program in Medicinal Chemistry, University of Michigan Medical School, Ann
Arbor, Michigan 48109, United States
| | - Carole A. Quesada
- Division of Nuclear Medicine, Department
of Radiology, ‡The Interdepartmental
Program in Medicinal Chemistry, University of Michigan Medical School, Ann
Arbor, Michigan 48109, United States
| | - Phillip Sherman
- Division of Nuclear Medicine, Department
of Radiology, ‡The Interdepartmental
Program in Medicinal Chemistry, University of Michigan Medical School, Ann
Arbor, Michigan 48109, United States
| | - Peter J. H. Scott
- Division of Nuclear Medicine, Department
of Radiology, ‡The Interdepartmental
Program in Medicinal Chemistry, University of Michigan Medical School, Ann
Arbor, Michigan 48109, United States
| | - Michael R. Kilbourn
- Division of Nuclear Medicine, Department
of Radiology, ‡The Interdepartmental
Program in Medicinal Chemistry, University of Michigan Medical School, Ann
Arbor, Michigan 48109, United States
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Fu H, Chen H, Doucet H. Palladium-catalyzed selective decarboxylative coupling reaction versus direct C―H arylation for arylation of heteroaromatics. Appl Organomet Chem 2013. [DOI: 10.1002/aoc.3037] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Affiliation(s)
- Haiyan Fu
- Key Laboratory of Green Chemistry and Technology, Ministry of Education, College of Chemistry; Sichuan University; Chengdu 610064 China
- Institut Sciences Chimiques de Rennes; UMR 6226 CNRS-Université de Rennes ‘Organométalliques, Matériaux et Catalyse’; 35042 Rennes France
| | - Hua Chen
- Key Laboratory of Green Chemistry and Technology, Ministry of Education, College of Chemistry; Sichuan University; Chengdu 610064 China
| | - Henri Doucet
- Institut Sciences Chimiques de Rennes; UMR 6226 CNRS-Université de Rennes ‘Organométalliques, Matériaux et Catalyse’; 35042 Rennes France
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Hubálek F, Binda C, Khalil A, Li M, Mattevi A, Castagnoli N, Edmondson DE. Demonstration of Isoleucine 199 as a Structural Determinant for the Selective Inhibition of Human Monoamine Oxidase B by Specific Reversible Inhibitors. J Biol Chem 2005; 280:15761-6. [PMID: 15710600 DOI: 10.1074/jbc.m500949200] [Citation(s) in RCA: 165] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Several reversible inhibitors selective for human monoamine oxidase B (MAO B) that do not inhibit MAO A have been described in the literature. The following compounds: 8-(3-chlorostyryl)caffeine, 1,4-diphenyl-2-butene, and trans,trans-farnesol are shown to inhibit competitively human, horse, rat, and mouse MAO B with K(i) values in the low micromolar range but are without effect on either bovine or sheep MAO B or human MAO A. In contrast, the reversible competitive inhibitor isatin binds to all known MAO B and MAO A with similar affinities. Sequence alignments and the crystal structures of human MAO B in complex with 1,4-diphenyl-2-butene or with trans,trans-farnesol provide molecular insights into these specificities. These inhibitors span the substrate and entrance cavities with the side chain of Ile-199 rotated out of its normal conformation suggesting that Ile-199 is gating the substrate cavity. Ile-199 is conserved in all known MAO B sequences except bovine MAO B, which has Phe in this position (the sequence of sheep MAO B is unknown). Phe is conserved in the analogous position in MAO A sequences. The human MAO B I199F mutant protein of MAO B binds to isatin (K(i) = 3 microM) but not to the three inhibitors listed above. The crystal structure of this mutant demonstrates that the side chain of Phe-199 interferes with the binding of those compounds. This suggests that the Ile-199 "gate" is a determinant for the specificity of these MAO B inhibitors and provides a molecular basis for the development of MAO B-specific reversible inhibitors without interference with MAO A function in neurotransmitter metabolism.
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Affiliation(s)
- Frantisek Hubálek
- Department of Biochemistry, Emory University, Atlanta, Georgia 30322, USA
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Five-Membered Ring Systems: Thiophenes & Se, Te Analogs. ACTA ACUST UNITED AC 2000. [DOI: 10.1016/s0959-6380(00)80008-2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register]
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