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Molecular Basis for Non-Covalent, Non-Competitive FAAH Inhibition. Int J Mol Sci 2022; 23:ijms232415502. [PMID: 36555144 PMCID: PMC9779292 DOI: 10.3390/ijms232415502] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/03/2022] [Revised: 12/01/2022] [Accepted: 12/03/2022] [Indexed: 12/13/2022] Open
Abstract
Fatty acid amide hydrolase (FAAH) plays a key role in the control of cannabinoid signaling and it represents a promising therapeutic strategy for the treatment of a wide range of diseases, including neuropathic pain and chronic inflammation. Starting from kinetics experiments carried out in our previous work for the most potent inhibitor 2-amino-3-chloropyridine amide (TPA14), we have investigated its non-competitive mechanism of action using molecular dynamics, thermodynamic integration and QM-MM/GBSA calculations. The computational studies highlighted the impact of mutations on the receptor binding pockets and elucidated the molecular basis of the non-competitive inhibition mechanism of TPA14, which prevents the endocannabinoid anandamide (AEA) from reaching its pro-active conformation. Our study provides a rationale for the design of non-competitive potent FAAH inhibitors for the treatment of neuropathic pain and chronic inflammation.
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Abstract
In this review, the state of the art for compounds affecting the endocannabinoid (eCB) system is described with a focus on the treatment of pain. Amongst directly acting CB receptor ligands, clinical experience with ∆9 -tetrahydracannabinol and medical cannabis in chronic non-cancer pain indicates that there are differences between the benefits perceived by patients and the at best modest effect seen in meta-analyses of randomized controlled trials. The reason for this difference is not known but may involve differences in the type of patients that are recruited, the study conditions that are chosen and the degree to which biases such as reporting bias are operative. Other directly acting CB receptor ligands such as biased agonists and allosteric receptor modulators have not yet reached the clinic. Amongst indirectly acting compounds targeting the enzymes responsible for the synthesis and catabolism of the eCBs anandamide and 2-arachidonoylglycerol, fatty acid amide hydrolase (FAAH) inhibitors have been investigated clinically but were per se not useful for the treatment of pain, although they may be useful for the treatment of post-traumatic stress disorder and cannabis use disorder. Dual-acting compounds targeting this enzyme and other targets such as cyclooxygenase-2 or transient potential vanilloid receptor 1 may be a way forward for the treatment of pain.
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Affiliation(s)
- C J Fowler
- From the, Department of Integrative Medical Biology, Umeå University, Umeå, Sweden
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3
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Fluorine nuclear magnetic resonance-based assay in living mammalian cells. Anal Biochem 2015; 495:52-9. [PMID: 26686030 DOI: 10.1016/j.ab.2015.11.015] [Citation(s) in RCA: 28] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/25/2015] [Revised: 11/17/2015] [Accepted: 11/24/2015] [Indexed: 12/18/2022]
Abstract
Nuclear magnetic resonance (NMR)-based screening has been recognized as a powerful approach for the identification and characterization of molecules interacting with pharmaceutical targets. Indeed, several NMR methods have been developed and successfully applied to many drug discovery projects. Whereas most of these approaches have targeted isolated biomolecular receptors, very few cases are reported with the screening performed in intact cells and cell extracts. Here we report the first successful application of the fluorine NMR-based assay n-FABS (n-fluorine atoms for biochemical screening) in living mammalian cells expressing the membrane protein fatty acid amide hydrolase (FAAH). This method allows the identification of both weak and potent inhibitors and the measurement of their potency in a physiological environment.
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Ogawa S, Kunugi H. Inhibitors of Fatty Acid Amide Hydrolase and Monoacylglycerol Lipase: New Targets for Future Antidepressants. Curr Neuropharmacol 2015; 13:760-75. [PMID: 26630956 PMCID: PMC4759315 DOI: 10.2174/1570159x13666150612225212] [Citation(s) in RCA: 38] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/24/2015] [Revised: 03/16/2015] [Accepted: 03/18/2015] [Indexed: 12/27/2022] Open
Abstract
Cannabis and analogs of Δ<sup>9</sup>-tetrahydrocannabinol have been used for therapeutic purposes, but their therapeutic use remains limited because of various adverse effects. Endogenous cannabinoids have been discovered, and dysregulation of endocannabinoid signaling is implicated in the pathophysiology of major depressive disorder (MDD). Recently, endocannabinoid hydrolytic enzymes such as fatty acid amide hydrolase (FAAH) and monoacylglycerol lipase (MAGL) have become new therapeutic targets in the treatment of MDD. Several FAAH or MAGL inhibitors are reported to have no cannabimimetic side effects and, therefore, are new potential therapeutic options for patients with MDD who are resistant to first-line antidepressants (selective serotonin and serotonin-norepinephrine reuptake inhibitors). In this review, we focus on the possible relationships between MDD and the endocannabinoid system as well as the inhibitors' therapeutic potential. MAGL inhibitors may reduce inflammatory responses through activation of cannabinoid receptor type 2. In the hypothalamic-pituitary-adrenal axis, repeated FAAH inhibitor administration may be beneficial for reducing circulating glucocorticoid levels. Both FAAH and MAGL inhibitors may contribute to dopaminergic system regulation. Recently, several new inhibitors have been developed with strong potency and selectivity. FAAH inhibitor, MAGL inhibitor, or dual blocker use would be promising new treatments for MDD. Further pre-clinical studies and clinical trials using these inhibitors are warranted.
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Affiliation(s)
| | - Hiroshi Kunugi
- Department of Mental Disorder Research, National Institute of Neuroscience, National Center of Neurology and Psychiatry, Kodaira, Tokyo, Japan.
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Hu SSJ, Ho YC, Chiou LC. No more pain upon Gq-protein-coupled receptor activation: role of endocannabinoids. Eur J Neurosci 2014; 39:467-84. [PMID: 24494686 DOI: 10.1111/ejn.12475] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/15/2013] [Revised: 12/02/2013] [Accepted: 12/05/2013] [Indexed: 01/24/2023]
Abstract
Marijuana has been used to relieve pain for centuries. The analgesic mechanism of its constituents, the cannabinoids, was only revealed after the discovery of cannabinoid receptors (CB1 and CB2) two decades ago. The subsequent identification of the endocannabinoids, anandamide and 2-arachidonoylglycerol (2-AG), and their biosynthetic and degradation enzymes discloses the therapeutic potential of compounds targeting the endocannabinoid system for pain control. Inhibitors of the anandamide and 2-AG degradation enzymes, fatty acid amide hydrolase and monoacylglycerol lipase, respectively, may be superior to direct cannabinoid receptor ligands as endocannabinoids are synthesized on demand and rapidly degraded, focusing action at generating sites. Recently, a promising strategy for pain relief was revealed in the periaqueductal gray (PAG). It is initiated by Gq-protein-coupled receptor (Gq PCR) activation of the phospholipase C-diacylglycerol lipase enzymatic cascade, generating 2-AG that produces inhibition of GABAergic transmission (disinhibition) in the PAG, thereby leading to analgesia. Here, we introduce the antinociceptive properties of exogenous cannabinoids and endocannabinoids, involving their biosynthesis and degradation processes, particularly in the PAG. We also review recent studies disclosing the Gq PCR-phospholipase C-diacylglycerol lipase-2-AG retrograde disinhibition mechanism in the PAG, induced by activating several Gq PCRs, including metabotropic glutamatergic (type 5 metabotropic glutamate receptor), muscarinic acetylcholine (M1/M3), and orexin 1 receptors. Disinhibition mediated by type 5 metabotropic glutamate receptor can be initiated by glutamate transporter inhibitors or indirectly by substance P, neurotensin, cholecystokinin and capsaicin. Finally, the putative role of 2-AG generated after activating the above neurotransmitter receptors in stress-induced analgesia is discussed.
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Affiliation(s)
- Sherry Shu-Jung Hu
- Department of Psychology, National Cheng Kung University, Tainan, Taiwan
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Chiou LC, Hu SSJ, Ho YC. Targeting the cannabinoid system for pain relief? ACTA ACUST UNITED AC 2013; 51:161-70. [PMID: 24529672 DOI: 10.1016/j.aat.2013.10.004] [Citation(s) in RCA: 42] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2013] [Accepted: 10/11/2013] [Indexed: 12/15/2022]
Abstract
Marijuana has been used to relieve pain for centuries, but its analgesic mechanism has only been understood during the past two decades. It is mainly mediated by its constituents, cannabinoids, through activating central cannabinoid 1 (CB1) receptors, as well as peripheral CB1 and CB2 receptors. CB2-selective agonists have the benefit of lacking CB1 receptor-mediated CNS side effects. Anandamide and 2-arachidonoylglycerol (2-AG) are two intensively studied endogenous lipid ligands of cannabinoid receptors, termed endocannabinoids, which are synthesized on demand and rapidly degraded. Thus, inhibitors of their degradation enzymes, fatty acid amide hydrolase and monoacylglycerol lipase (MAGL), respectively, may be superior to direct cannabinoid receptor ligands as a promising strategy for pain relief. In addition to the antinociceptive properties of exogenous cannabinoids and endocannabinoids, involving their biosynthesis and degradation processes, we also review recent studies that revealed a novel analgesic mechanism, involving 2-AG in the periaqueductal gray (PAG), a midbrain region for initiating descending pain inhibition. It is initiated by Gq-protein-coupled receptor (GqPCR) activation of the phospholipase C (PLC)-diacylglycerol lipase (DAGL) enzymatic cascade, generating 2-AG that produces inhibition of GABAergic transmission (disinhibition) in the PAG, thereby leading to analgesia. This GqPCR-PLC-DAGL-2-AG retrograde disinhibition mechanism in the PAG can be initiated by activating type 5 metabotropic glutamate receptor (mGluR5), muscarinic acetylcholine (M1/M3), and orexin (OX1) receptors. mGluR5-mediated disinhibition can be initiated by glutamate transporter inhibitors, or indirectly by substance P, neurotensin, cholecystokinin, capsaicin, and AM404, the bioactive metabolite of acetaminophen in the brain. The putative role of 2-AG generated after activating the above neurotransmitter receptors in stress-induced analgesia is also discussed.
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Affiliation(s)
- Lih-Chu Chiou
- Graduate Institute of Pharmacology, College of Medicine, National Taiwan University, Taipei, Taiwan; Department of Pharmacology, National Taiwan University, Taipei, Taiwan; Graduate Institute of Brain and Mind Sciences, College of Medicine, National Taiwan University, Taipei, Taiwan; Neurobiology and Cognitive Science Center, National Taiwan University, Taipei, Taiwan.
| | - Sherry Shu-Jung Hu
- Department of Psychology, National Cheng Kung University, Tainan, Taiwan
| | - Yu-Cheng Ho
- Graduate Institute of Pharmacology, College of Medicine, National Taiwan University, Taipei, Taiwan
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Almukadi H, Wu H, Böhlke M, Kelley CJ, Maher TJ, Pino-Figueroa A. The macamide N-3-methoxybenzyl-linoleamide is a time-dependent fatty acid amide hydrolase (FAAH) inhibitor. Mol Neurobiol 2013; 48:333-9. [PMID: 23853040 DOI: 10.1007/s12035-013-8499-2] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/12/2013] [Accepted: 06/19/2013] [Indexed: 10/26/2022]
Abstract
The Peruvian plant Lepidium meyenii (Maca) has been shown to possess neuroprotective activity both in vitro and in vivo. Previous studies have also demonstrated the activity of the pentane extract and its macamides, the most representative lipophilic constituents of Maca, in the endocannabinoid system as fatty acid amide hydrolase (FAAH) inhibitors. One of the most active macamides, N-3-methoxybenzyl-linoleamide, was studied to determine its mechanism of interaction with FAAH and whether it has inhibitory activity on mono-acyl glycerol lipase (MAGL), the second enzyme responsible for endocannabinoid degradation. Macamide concentrations from 1 to 100 μM were tested using FAAH and MAGL inhibitor assay methods and showed no effect on MAGL. Tests with other conditions were performed in order to characterize the inhibitory mechanism of FAAH inhibition. N-3-methoxybenzyl-linoleamide displayed significant time-dependent and dose-dependent FAAH inhibitory activity. The mechanism of inhibition was most likely irreversible or slowly reversible. These results suggest the potential application of macamides isolated from Maca as FAAH inhibitors, as they might act on the central nervous system to provide analgesic, anti-inflammatory, or neuroprotective effects, by modulating the release of neurotransmitters.
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Affiliation(s)
- Haifa Almukadi
- Department of Pharmaceutical Sciences, MCPHS University, 179 Longwood Ave., Boston, MA, 02115, USA
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Liu P, Hamill TG, Chioda M, Chobanian H, Fung S, Guo Y, Chang L, Bakshi R, Hong Q, Dellureficio J, Lin LS, Abbadie C, Alexander J, Jin H, Mandala S, Shiao LL, Li W, Sanabria S, Williams D, Zeng Z, Hajdu R, Jochnowitz N, Rosenbach M, Karanam B, Madeira M, Salituro G, Powell J, Xu L, Terebetski JL, Leone JF, Miller P, Cook J, Holahan M, Joshi A, O’Malley S, Purcell M, Posavec D, Chen TB, Riffel K, Williams M, Hargreaves R, Sullivan KA, Nargund RP, DeVita RJ. Discovery of MK-3168: A PET Tracer for Imaging Brain Fatty Acid Amide Hydrolase. ACS Med Chem Lett 2013; 4:509-13. [PMID: 24900701 DOI: 10.1021/ml4000996] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/11/2013] [Accepted: 04/20/2013] [Indexed: 11/29/2022] Open
Abstract
We report herein the discovery of a fatty acid amide hydrolase (FAAH) positron emission tomography (PET) tracer. Starting from a pyrazole lead, medicinal chemistry efforts directed toward reducing lipophilicity led to the synthesis of a series of imidazole analogues. Compound 6 was chosen for further profiling due to its appropriate physical chemical properties and excellent FAAH inhibition potency across species. [(11)C]-6 (MK-3168) exhibited good brain uptake and FAAH-specific signal in rhesus monkeys and is a suitable PET tracer for imaging FAAH in the brain.
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Affiliation(s)
| | - Terence G. Hamill
- Department of Imaging Research, Merck Research Laboratories, West Point, Pennsylvania
19486, United States
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | - Wenping Li
- Department of Imaging Research, Merck Research Laboratories, West Point, Pennsylvania
19486, United States
| | - Sandra Sanabria
- Department of Imaging Research, Merck Research Laboratories, West Point, Pennsylvania
19486, United States
| | - David Williams
- Department of Imaging Research, Merck Research Laboratories, West Point, Pennsylvania
19486, United States
| | - Zhizhen Zeng
- Department of Imaging Research, Merck Research Laboratories, West Point, Pennsylvania
19486, United States
| | | | | | | | | | | | | | | | | | | | | | - Patricia Miller
- Department of Imaging Research, Merck Research Laboratories, West Point, Pennsylvania
19486, United States
| | - Jacquelynn Cook
- Department of Imaging Research, Merck Research Laboratories, West Point, Pennsylvania
19486, United States
| | - Marie Holahan
- Department of Imaging Research, Merck Research Laboratories, West Point, Pennsylvania
19486, United States
| | - Aniket Joshi
- Department of Imaging Research, Merck Research Laboratories, West Point, Pennsylvania
19486, United States
| | - Stacey O’Malley
- Department of Imaging Research, Merck Research Laboratories, West Point, Pennsylvania
19486, United States
| | - Mona Purcell
- Department of Imaging Research, Merck Research Laboratories, West Point, Pennsylvania
19486, United States
| | - Diane Posavec
- Department of Imaging Research, Merck Research Laboratories, West Point, Pennsylvania
19486, United States
| | - Tsing-Bau Chen
- Department of Imaging Research, Merck Research Laboratories, West Point, Pennsylvania
19486, United States
| | - Kerry Riffel
- Department of Imaging Research, Merck Research Laboratories, West Point, Pennsylvania
19486, United States
| | - Mangay Williams
- Department of Imaging Research, Merck Research Laboratories, West Point, Pennsylvania
19486, United States
| | - Richard Hargreaves
- Department of Imaging Research, Merck Research Laboratories, West Point, Pennsylvania
19486, United States
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1,3,4-Oxadiazol-2-ones as fatty-acid amide hydrolase and monoacylglycerol lipase inhibitors: Synthesis, in vitro evaluation and insight into potency and selectivity determinants by molecular modelling. Eur J Pharm Sci 2013; 49:423-33. [PMID: 23557840 DOI: 10.1016/j.ejps.2013.03.015] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/14/2013] [Revised: 02/28/2013] [Accepted: 03/18/2013] [Indexed: 01/15/2023]
Abstract
Inhibition of the key hydrolytic enzymes of the endocannabinoid system, fatty acid amide hydrolase (FAAH) and monoacylglycerol lipase (MAGL), has been proposed as potential mode of action for various therapeutic applications. Continuing our previous work, we take the first steps of structure-activity relationship exploration and show that 1,3,4-oxadiazol-2-ones can serve as scaffold for both selective FAAH and MAGL inhibitors, and also function as a dual FAAH/MAGL inhibitor at sub-micromolar IC50 values. Moreover, 10-fold selectivity against MAGL over FAAH was achieved with compound 3d (FAAH and MAGL IC50; 2.0 and 0.22 μM). Lastly, enzyme and ligand features contributing to the potency and selectivity differences are analysed by molecular docking.
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Heteroaryl urea inhibitors of fatty acid amide hydrolase: Structure–mutagenicity relationships for arylamine metabolites. Bioorg Med Chem Lett 2012; 22:7357-62. [DOI: 10.1016/j.bmcl.2012.10.076] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/29/2012] [Revised: 10/08/2012] [Accepted: 10/15/2012] [Indexed: 11/21/2022]
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Estiarte MA, Johnson RJ, Kaub CJ, Gowlugari S, O'Mahony DJR, Nguyen MT, Emerling DE, Kelly MG, Kincaid J, Vincent F, Duncton MAJ. 2-Amino-5-arylbenzoxazole derivatives as potent inhibitors of fatty acid amide hydrolase (FAAH). MEDCHEMCOMM 2012. [DOI: 10.1039/c2md00307d] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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