1
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Walby GD, Gu Q, Yang H, Martin SF. Structure-Affinity relationships of novel σ 2R/TMEM97 ligands. Bioorg Chem 2024; 145:107191. [PMID: 38432153 DOI: 10.1016/j.bioorg.2024.107191] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/28/2023] [Revised: 01/24/2024] [Accepted: 02/06/2024] [Indexed: 03/05/2024]
Abstract
The sigma 2 receptor (σ2R), which was recently identified as the transmembrane protein 97 (TMEM97), is increasingly attracting interest as a possible therapeutic target for indications in neuroscience. Toward identifying novel modulators of σ2R/TMEM97, we prepared a collection of benzoxazocine, benzomorphan, and methanobenzazepine ligands related to the known bioactive norbenzomorphans DKR-1677, FEM-1689, and EES-1686 and determined their Ki values for σ2R/TMEM97 and the sigma 1 receptor (σ1R). The σ2R/TMEM97 binding affinities and selectivities relative to σ1R of these new benzoxazocine, benzomorphan, and methanobenzazepine analogs are lower, often significantly lower, than their respective norbenzomorphan counterparts, suggesting the spatial orientation of pharmacophoric substituents is critical for binding to the two proteins. The benzoxazocine, benzomorphan, and methanobenzazepine congeners of DKR-1677 and FEM-1689 tend to be weakly selective for σ2R/TMEM97 versus σ1R, whereas EES-1686 derivatives exhibit the greatest selectivity, suggesting the size and/or nature of the substituent on the nitrogen atom of the scaffold may be important for selectivity. Computational docking studies were performed for the 1S,5R-and 1R,5S-enantiomers of DKR-1677, FEM-1689, and EES-1686 and their benzoxazocine, benzomorphan, and methanobenzazepine counterparts. These computations predict that the protonated amino group of each ligand forms a highly conserved salt bridge and a H-bonding interaction with Asp29 as well as a cation-π interaction with Tyr150 of σ2R/TMEM97. These electrostatic interactions are major driving forces for binding to σ2R/TMEM97 and are similar, though not identical, for each ligand. Other interactions within the well-defined binding pocket also tend to be comparable, but there are some major differences in how the hydrophobic aryl groups of various ligands interact with the protein surface external to the binding pocket. Overall, these studies show that the orientations of aryl and N-substituents on the norbenzomorphan and related scaffolds are important determinants of binding affinity of σ2R/TMEM97 ligands, and small changes can have significant effects upon binding profiles.
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Affiliation(s)
- Grant D Walby
- Department of Chemistry, The University of Texas at Austin, Austin, TX 78712, United States
| | - Qi Gu
- Department of Chemistry, The University of Texas at Austin, Austin, TX 78712, United States
| | - Hongfen Yang
- Department of Chemistry, The University of Texas at Austin, Austin, TX 78712, United States
| | - Stephen F Martin
- Department of Chemistry, The University of Texas at Austin, Austin, TX 78712, United States.
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2
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Yousuf MS, Sahn JJ, Yang H, David ET, Shiers S, Mancilla Moreno M, Iketem J, Royer DM, Garcia CD, Zhang J, Hong VM, Mian SM, Ahmad A, Kolber BJ, Liebl DJ, Martin SF, Price TJ. Highly specific σ 2R/TMEM97 ligand FEM-1689 alleviates neuropathic pain and inhibits the integrated stress response. Proc Natl Acad Sci U S A 2023; 120:e2306090120. [PMID: 38117854 PMCID: PMC10756276 DOI: 10.1073/pnas.2306090120] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/14/2023] [Accepted: 11/21/2023] [Indexed: 12/22/2023] Open
Abstract
The sigma 2 receptor (σ2R) was described pharmacologically more than three decades ago, but its molecular identity remained obscure until recently when it was identified as transmembrane protein 97 (TMEM97). We and others have shown that σ2R/TMEM97 ligands alleviate mechanical hypersensitivity in mouse neuropathic pain models with a time course wherein maximal antinociceptive effect is approximately 24 h following dosing. We sought to understand this unique antineuropathic pain effect by addressing two key questions: do these σ2R/TMEM97 compounds act selectively via the receptor, and what is their downstream mechanism on nociceptive neurons? Using male and female conventional knockout mice for Tmem97, we find that a σ2R/TMEM97 binding compound, FEM-1689, requires the presence of the gene to produce antinociception in the spared nerve injury model in mice. Using primary mouse dorsal root ganglion neurons, we demonstrate that FEM-1689 inhibits the integrated stress response (ISR) and promotes neurite outgrowth via a σ2R/TMEM97-specific action. We extend the clinical translational value of these findings by showing that FEM-1689 reduces ISR and p-eIF2α levels in human sensory neurons and that it alleviates the pathogenic engagement of ISR by methylglyoxal. We also demonstrate that σ2R/TMEM97 is expressed in human nociceptors and satellite glial cells. These results validate σ2R/TMEM97 as a promising target for further development for the treatment of neuropathic pain.
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Affiliation(s)
- Muhammad Saad Yousuf
- Center for Advanced Pain Studies and Department of Neuroscience, School of Behavioral and Brain Sciences, University of Texas at Dallas, Richardson, TX75080
- NuvoNuro Inc., Austin, TX78712
| | - James J. Sahn
- NuvoNuro Inc., Austin, TX78712
- Department of Chemistry, University of Texas at Austin, Austin, TX78712
| | - Hongfen Yang
- Department of Chemistry, University of Texas at Austin, Austin, TX78712
| | - Eric T. David
- Center for Advanced Pain Studies and Department of Neuroscience, School of Behavioral and Brain Sciences, University of Texas at Dallas, Richardson, TX75080
| | - Stephanie Shiers
- Center for Advanced Pain Studies and Department of Neuroscience, School of Behavioral and Brain Sciences, University of Texas at Dallas, Richardson, TX75080
| | - Marisol Mancilla Moreno
- Center for Advanced Pain Studies and Department of Neuroscience, School of Behavioral and Brain Sciences, University of Texas at Dallas, Richardson, TX75080
| | - Jonathan Iketem
- Center for Advanced Pain Studies and Department of Neuroscience, School of Behavioral and Brain Sciences, University of Texas at Dallas, Richardson, TX75080
| | - Danielle M. Royer
- Center for Advanced Pain Studies and Department of Neuroscience, School of Behavioral and Brain Sciences, University of Texas at Dallas, Richardson, TX75080
| | - Chelsea D. Garcia
- Center for Advanced Pain Studies and Department of Neuroscience, School of Behavioral and Brain Sciences, University of Texas at Dallas, Richardson, TX75080
| | - Jennifer Zhang
- Center for Advanced Pain Studies and Department of Neuroscience, School of Behavioral and Brain Sciences, University of Texas at Dallas, Richardson, TX75080
| | - Veronica M. Hong
- Center for Advanced Pain Studies and Department of Neuroscience, School of Behavioral and Brain Sciences, University of Texas at Dallas, Richardson, TX75080
| | - Subhaan M. Mian
- Center for Advanced Pain Studies and Department of Neuroscience, School of Behavioral and Brain Sciences, University of Texas at Dallas, Richardson, TX75080
| | - Ayesha Ahmad
- Center for Advanced Pain Studies and Department of Neuroscience, School of Behavioral and Brain Sciences, University of Texas at Dallas, Richardson, TX75080
| | - Benedict J. Kolber
- Center for Advanced Pain Studies and Department of Neuroscience, School of Behavioral and Brain Sciences, University of Texas at Dallas, Richardson, TX75080
| | - Daniel J. Liebl
- The Miami Project to Cure Paralysis, Department of Neurosurgery, University of Miami Miller School of Medicine, Miami, FL33136
| | - Stephen F. Martin
- NuvoNuro Inc., Austin, TX78712
- Department of Chemistry, University of Texas at Austin, Austin, TX78712
| | - Theodore J. Price
- Center for Advanced Pain Studies and Department of Neuroscience, School of Behavioral and Brain Sciences, University of Texas at Dallas, Richardson, TX75080
- NuvoNuro Inc., Austin, TX78712
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3
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Yousuf MS, Sahn JJ, Yang H, David ET, Shiers S, Moreno MM, Iketem J, Royer DM, Garcia CD, Zhang J, Hong VM, Mian SM, Ahmad A, Kolber BJ, Liebl DJ, Martin SF, Price TJ. Highly specific σ 2R/TMEM97 ligand alleviates neuropathic pain and inhibits the integrated stress response. bioRxiv 2023:2023.04.11.536439. [PMID: 37090527 PMCID: PMC10120691 DOI: 10.1101/2023.04.11.536439] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/25/2023]
Abstract
The Sigma 2 receptor (σ2R) was described pharmacologically more than three decades ago, but its molecular identity remained obscure until recently when it was identified as transmembrane protein 97 (TMEM97). We and others have shown that σ2R/TMEM97 ligands alleviate mechanical hypersensitivity in mouse neuropathic pain models with a time course wherein maximal anti-nociceptive effect is approximately 24 hours following dosing. We sought to understand this unique anti-neuropathic pain effect by addressing two key questions: do these σ2R/TMEM97 compounds act selectively via the receptor, and what is their downstream mechanism on nociceptive neurons? Using male and female conventional knockout (KO) mice for Tmem97, we find that a new σ2R/TMEM97 binding compound, FEM-1689, requires the presence of the gene to produce anti-nociception in the spared nerve injury model in mice. Using primary mouse dorsal root ganglion (DRG) neurons, we demonstrate that FEM-1689 inhibits the integrated stress response (ISR) and promotes neurite outgrowth via a σ2R/TMEM97-specific action. We extend the clinical translational value of these findings by showing that FEM-1689 reduces ISR and p-eIF2α levels in human sensory neurons and that it alleviates the pathogenic engagement of ISR by methylglyoxal. We also demonstrate that σ2R/TMEM97 is expressed in human nociceptors and satellite glial cells. These results validate σ2R/TMEM97 as a promising target for further development for the treatment of neuropathic pain.
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Affiliation(s)
- Muhammad Saad Yousuf
- Center for Advanced Pain Studies and Department of Neuroscience, School of Behavioral and Brain Sciences, University of Texas at Dallas, Richardson, TX 75080
- NuvoNuro, Austin, TX 78712
| | - James J. Sahn
- Department of Chemistry, University of Texas at Austin, Austin, TX 78712
- NuvoNuro, Austin, TX 78712
| | - Hongfen Yang
- Department of Chemistry, University of Texas at Austin, Austin, TX 78712
| | - Eric T. David
- Center for Advanced Pain Studies and Department of Neuroscience, School of Behavioral and Brain Sciences, University of Texas at Dallas, Richardson, TX 75080
| | - Stephanie Shiers
- Center for Advanced Pain Studies and Department of Neuroscience, School of Behavioral and Brain Sciences, University of Texas at Dallas, Richardson, TX 75080
| | - Marisol Mancilla Moreno
- Center for Advanced Pain Studies and Department of Neuroscience, School of Behavioral and Brain Sciences, University of Texas at Dallas, Richardson, TX 75080
| | - Jonathan Iketem
- Center for Advanced Pain Studies and Department of Neuroscience, School of Behavioral and Brain Sciences, University of Texas at Dallas, Richardson, TX 75080
| | - Danielle M. Royer
- Center for Advanced Pain Studies and Department of Neuroscience, School of Behavioral and Brain Sciences, University of Texas at Dallas, Richardson, TX 75080
| | - Chelsea D. Garcia
- Center for Advanced Pain Studies and Department of Neuroscience, School of Behavioral and Brain Sciences, University of Texas at Dallas, Richardson, TX 75080
| | - Jennifer Zhang
- Center for Advanced Pain Studies and Department of Neuroscience, School of Behavioral and Brain Sciences, University of Texas at Dallas, Richardson, TX 75080
| | - Veronica M. Hong
- Center for Advanced Pain Studies and Department of Neuroscience, School of Behavioral and Brain Sciences, University of Texas at Dallas, Richardson, TX 75080
| | - Subhaan M. Mian
- Center for Advanced Pain Studies and Department of Neuroscience, School of Behavioral and Brain Sciences, University of Texas at Dallas, Richardson, TX 75080
| | - Ayesha Ahmad
- Center for Advanced Pain Studies and Department of Neuroscience, School of Behavioral and Brain Sciences, University of Texas at Dallas, Richardson, TX 75080
| | - Benedict J. Kolber
- Center for Advanced Pain Studies and Department of Neuroscience, School of Behavioral and Brain Sciences, University of Texas at Dallas, Richardson, TX 75080
| | | | - Stephen F. Martin
- Department of Chemistry, University of Texas at Austin, Austin, TX 78712
- NuvoNuro, Austin, TX 78712
| | - Theodore J. Price
- Center for Advanced Pain Studies and Department of Neuroscience, School of Behavioral and Brain Sciences, University of Texas at Dallas, Richardson, TX 75080
- NuvoNuro, Austin, TX 78712
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4
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Lu Y, Gu Q, Martin SF. Structure-affinity relationships of stereoisomers of norbenzomorphan-derived σ 2R/TMEM97 modulators. Eur J Med Chem 2023; 257:115488. [PMID: 37247506 DOI: 10.1016/j.ejmech.2023.115488] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/17/2023] [Revised: 04/24/2023] [Accepted: 05/13/2023] [Indexed: 05/31/2023]
Abstract
The sigma 2 receptor (σ2R), which is identical to transmembrane protein 97 (TMEM97), is attracting increasing interest as a possible therapeutic target for various indications in neuroscience. In continuation of a program to identify novel compounds that bind with high affinity and selectivity to σ2R/TMEM97, we performed structure-affinity-relationship (SAfiR) studies of several sets of σ2R/TMEM97 ligands having a B-norbenzomorphan ring core. Binding data for σ2R/TMEM97 and σ1R of several enantiomeric pairs of piperazine-substituted norbenzomorphans show the (1S,5R)-enantiomers have affinities (Ki = 9-75 nM) for σ2R/TMEM97 that are 2-3-fold higher than their enantiomorphic (1R,5S)-analogs; however, there is no clear trend for selectivity for σ2R/TMEM97 vs σ1R. A series of N-alkyl piperazino (1S,5R)-norbenzomorphans was then evaluated, and with the exception of compounds having N-alkyl groups substituted with oxygen or amino groups at C (2) of an ethylene chain, Ki values for σ2R/TMEM97 are less than 25 nM, and several compounds have good selectivities (ca 7-16-fold) for σ2R/TMEM97 vs σ1R. Mono-substituted carbobenzyloxy analogs have Ki values for σ2R/TMEM97 comparable to the unsubstituted parent (Ki = ca 7-27 nM), but replacing the N-acyloxy group with N-acyl or N-arylsulfonyl groups provides analogs having lower affinity and selectivity. Some congeners with bioisosteric replacements of the piperazine group on the (1S,5R)-norbenzomorphan core have high affinity (Ki = <30 nM) for σ2R/TMEM97, but selectivities are modest. Computational docking studies for racemic pairs of piperazino norbenzomorphans show that individual (1S,5R)- and (1R,5S)-enantiomers adopt distinct poses upon binding to σ2R/TMEM97, whereas ligands belongingto the same enantiomeric series adopt closely similar binding poses. The protonated amino group in each of the enantiomorphic ligands engages in highly conserved salt bridges with Asp29 and cation-π interactions with Tyr150 that are the primary determinants of binding affinity. There is no correlation between any of the computational parameter outputs and Ki values, but this is unsurprising given the small energetic differences involved. Modeling also suggest sthat some compounds can extend deeper into σ2R/TMEM97 binding pocket forming salt bridges with Glu73.
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Affiliation(s)
- Yan Lu
- Department of Chemistry, The University of Texas at Austin, Austin, TX, 78712, United States
| | - Qi Gu
- Department of Chemistry, The University of Texas at Austin, Austin, TX, 78712, United States
| | - Stephen F Martin
- Department of Chemistry, The University of Texas at Austin, Austin, TX, 78712, United States.
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Wang H, Peng Z, Li Y, Sahn JJ, Hodges TR, Chou TH, Liu Q, Zhou X, Jiao S, Porciatti V, Liebl DJ, Martin SF, Wen R. σ 2R/TMEM97 in retinal ganglion cell degeneration. Sci Rep 2022; 12:20753. [PMID: 36456686 PMCID: PMC9715665 DOI: 10.1038/s41598-022-24537-3] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/10/2022] [Accepted: 11/16/2022] [Indexed: 12/02/2022] Open
Abstract
The sigma 2 receptor (σ2R) was recently identified as an endoplasmic reticulum (ER) membrane protein known as transmembrane protein 97 (TMEM97). Studies have shown that σ2R/TMEM97 binding compounds are neuroprotective, suggesting a role of σ2R/TMEM97 in neurodegenerative processes. To understand the function of σ2R/TMEM97 in neurodegeneration pathways, we characterized ischemia-induced retinal ganglion cell (RGC) degeneration in TMEM97-/- mice and found that RGCs in TMEM97-/- mice are resistant to degeneration. In addition, intravitreal injection of a selective σ2R/TMEM97 ligand DKR-1677 significantly protects RGCs from ischemia-induced degeneration in wildtype mice. Our results provide conclusive evidence that σ2R/TMEM97 plays a role to facilitate RGC death following ischemic injury and that inhibiting the function of σ2R/TMEM97 is neuroprotective. This work is a breakthrough toward elucidating the biology and function of σ2R/TMEM97 in RGCs and likely in other σ2R/TMEM97 expressing neurons. Moreover, these findings support future studies to develop new neuroprotective approaches for RGC degenerative diseases by inhibiting σ2R/TMEM97.
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Affiliation(s)
- Hua Wang
- Bascom Palmer Eye Institute, University of Miami, Miller School of Medicine, Miami, FL, 33136, USA
| | - Zhiyou Peng
- Bascom Palmer Eye Institute, University of Miami, Miller School of Medicine, Miami, FL, 33136, USA
| | - Yiwen Li
- Bascom Palmer Eye Institute, University of Miami, Miller School of Medicine, Miami, FL, 33136, USA
| | - James J Sahn
- Department of Chemistry and Biochemistry, University of Texas at Austin, Austin, TX, 78712, USA
| | - Timothy R Hodges
- Department of Chemistry and Biochemistry, University of Texas at Austin, Austin, TX, 78712, USA
| | - Tsung-Han Chou
- Bascom Palmer Eye Institute, University of Miami, Miller School of Medicine, Miami, FL, 33136, USA
| | - Qiong Liu
- Bascom Palmer Eye Institute, University of Miami, Miller School of Medicine, Miami, FL, 33136, USA
| | - Xuezhi Zhou
- Bascom Palmer Eye Institute, University of Miami, Miller School of Medicine, Miami, FL, 33136, USA
| | - Shuliang Jiao
- Department of Biomedical Engineering, Florida International University, Miami, FL, 33174, USA
| | - Vittorio Porciatti
- Bascom Palmer Eye Institute, University of Miami, Miller School of Medicine, Miami, FL, 33136, USA
| | - Daniel J Liebl
- Department of Neurosurgery, University of Miami, Miller School of Medicine, Miami, FL, 33136, USA
| | - Stephen F Martin
- Department of Chemistry and Biochemistry, University of Texas at Austin, Austin, TX, 78712, USA.
| | - Rong Wen
- Bascom Palmer Eye Institute, University of Miami, Miller School of Medicine, Miami, FL, 33136, USA.
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Jin J, Arbez N, Sahn JJ, Lu Y, Linkens KT, Hodges TR, Tang A, Wiseman R, Martin SF, Ross CA. Neuroprotective Effects of σ 2R/TMEM97 Receptor Modulators in the Neuronal Model of Huntington's Disease. ACS Chem Neurosci 2022; 13:2852-2862. [PMID: 36108101 PMCID: PMC9547941 DOI: 10.1021/acschemneuro.2c00274] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023] Open
Abstract
Huntington's disease (HD) is a genetic neurodegenerative disease caused by an expanded CAG repeat in the Huntingtin (HTT) gene that encodes for an expanded polyglutamine (polyQ) repeat in exon-1 of the human mutant huntingtin (mHTT) protein. The presence of this polyQ repeat results in neuronal degeneration, for which there is no cure or treatment that modifies disease progression. In previous studies, we have shown that small molecules that bind selectively to σ2R/TMEM97 can have significant neuroprotective effects in models of Alzheimer's disease, traumatic brain injury, and several other neurodegenerative diseases. In the present work, we extend these investigations and show that certain σ2R/TMEM97-selective ligands decrease mHTT-induced neuronal toxicity. We first synthesized a set of compounds designed to bind to σ2R/TMEM97 and determined their binding profiles (Ki values) for σ2R/TMEM97 and other proteins in the central nervous system. Modulators with high affinity and selectivity for σ2R/TMEM97 were then tested in our HD cell model. Primary cortical neurons were cultured in vitro for 7 days and then co-transfected with either a normal HTT construct (Htt N-586-22Q/GFP) or the mHTT construct Htt-N586-82Q/GFP. Transfected neurons were treated with either σ2R/TMEM97 or σ1R modulators for 48 h. After treatment, neurons were fixed and stained with Hoechst, and condensed nuclei were quantified to assess cell death in the transfected neurons. Significantly, σ2R/TMEM97 modulators reduce the neuronal toxicity induced by mHTT, and their neuroprotective effects are not blocked by NE-100, a selective σ1R antagonist known to block neuroprotection by σ1R ligands. These results indicate for the first time that σ2R/TMEM97 modulators can protect neurons from mHTT-induced neuronal toxicity, suggesting that targeting σ2R/TMEM97 may lead to a novel therapeutic approach to treat patients with HD.
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Affiliation(s)
- Jing Jin
- Division of Neurobiology, Department of Psychiatry, Johns Hopkins University School of Medicine, Baltimore Maryland, 21287, United States
| | - Nicolas Arbez
- Division of Neurobiology, Department of Psychiatry, Johns Hopkins University School of Medicine, Baltimore Maryland, 21287, United States.,Cellular Sciences Department, IdRS, Croissy-sur-Seine, France
| | - James J. Sahn
- Department of Chemistry, The University of Texas at Austin, Austin, TX, 78712, United States
| | - Yan Lu
- Department of Chemistry, The University of Texas at Austin, Austin, TX, 78712, United States
| | - Kathryn T. Linkens
- Department of Chemistry, The University of Texas at Austin, Austin, TX, 78712, United States
| | - Timothy R. Hodges
- Department of Chemistry, The University of Texas at Austin, Austin, TX, 78712, United States
| | - Anthony Tang
- Division of Neurobiology, Department of Psychiatry, Johns Hopkins University School of Medicine, Baltimore Maryland, 21287, United States
| | - Robyn Wiseman
- Division of Neurobiology, Department of Psychiatry, Johns Hopkins University School of Medicine, Baltimore Maryland, 21287, United States.,Department of Pharmacology and Molecular Sciences, Johns Hopkins University School of Medicine, Baltimore, Maryland, 21287, United States
| | - Stephen F. Martin
- Department of Chemistry, The University of Texas at Austin, Austin, TX, 78712, United States,equally contributed co-senior authors to whom correspondence may be addressed: ;
| | - Christopher A. Ross
- Division of Neurobiology, Department of Psychiatry, Johns Hopkins University School of Medicine, Baltimore Maryland, 21287, United States.,Departments of Neurology, Neuroscience and Pharmacology, Johns Hopkins University School of Medicine, Baltimore, Maryland, 21287, United States.,equally contributed co-senior authors to whom correspondence may be addressed: ;
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7
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Abstract
Scientific excursions into the unknown are often characterized by unanticipated twists and turns that may lead in directions that never could have been predicted. Decisions made during the course of these explorations determine what we discover. This Account chronicles one such journey that began with a challenge encountered during the synthesis of a natural product and then unfolded over more than 30 years to focus on unmet needs in neuroscience. Specifically, while developing a concise approach to tetrahydroalstonine, a heteroyohimboid alkaloid having α-adrenergic activity, we faced the predicament of assembling a key intermediate. Solving this problem resulted in the serendipitous discovery of the vinylogous Mannich reaction and a productive program wherein we used this powerful construction as a key step in the syntheses of numerous alkaloids. However, we also realized that lessons learned from the synthesis of tetrahydroalstonine could be generalized to invent a new strategy for preparing diverse collections of substituted nitrogen heterocycles that could be screened against biological targets. The approach featured the combination of several reactants in a multicomponent assembly process to give a functionalized intermediate that could be elaborated by various ring-forming reactions to give heterocyclic scaffolds that could be further diversified. Screening these compound sets against a broad range of biological targets revealed some intriguing hits, but none of them led to a productive collaboration in translational research. Notwithstanding this setback, we screened curated members of our collections against proteins in the central nervous system and discovered some substituted B-norbenzomorphans that were selective for the enigmatic sigma-2 receptor (σ2R), an understudied protein that had been primarily associated with cancer. With scant knowledge of its role in neuroscience, we posited that small molecules that bind to σ2R might be neuroprotective, thus launching a new venture. In parallel investigations we prepared analogues of the initial hits, explored their effects in animal models of neurodegenerative and neurological conditions, and identified σ2R as transmembrane protein 97 (TMEM97). After first establishing the neuroprotective effects of several σ2R/TMEM97 ligands in a transgenic Caenorhabditis elegans model of neurodegeneration, we showed that one of these has procognitive effects and reduces levels of proinflammatory cytokines in a transgenic mouse model of Alzheimer's disease. We then identified a closely related σ2R/TMEM97 ligand that mitigates hippocampal-dependent memory deficits, prevents axon degeneration, and protects neurons and oligodendrocytes after traumatic brain injury. In a recent study, this compound was shown to protect retinal ganglion cells from retinal ischemia/reperfusion injury. In other collaborative investigations, we have shown that related, but structurally distinct, σ2R/TMEM97 ligands alleviate neuropathic pain, while a σ2R/TMEM97 ligand representing yet another chemotype reduces impairments associated with alcohol withdrawal. More recently, we have shown that σ2R/TMEM97 ligands enhance survival of cortical neurons in a neuronal model of Huntington's disease. Translational and mechanistic studies in these and other areas are in progress. Solving a problem we faced in natural product synthesis thus served as an unexpected gateway to discoveries that could lead to entirely new approaches to treat neurodegenerative and neurological conditions by targeting σ2R/TMEM97, a protein that has never been associated with these afflictions.
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Affiliation(s)
- Stephen F Martin
- Department of Chemistry, The University of Texas at Austin, Austin, Texas 78712, United States
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8
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Affiliation(s)
- Zhipeng Wang
- Department of Chemistry The University of Texas at Austin Austin Texas 78712 USA
| | - Stephen F. Martin
- Department of Chemistry The University of Texas at Austin Austin Texas 78712 USA
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9
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Abstract
The one-step syntheses of exotine A and exotine B, which comprise the unusual coumarin-cyclohepta[b]indole ring system, have been achieved via the biomimetically inspired combination of indole, prenal, and either trans-dehydroosthol or gleinadiene. This facile three-component reaction delivered a mixture (17:1) of exotine A and 11'-epi-exotine A in a 43% yield from trans-dehydroosthol and a mixture (4:1) of exotine B and 11'-epi-exotine B in a 50% yield from gleinadiene. Some mechanistic aspects of this process were explored, and spectral evidence for 3,3'-spiroindolenine intermediates was obtained. Moreover, a skeletal isomer of exotine A that likely originates from a 1,2-alkyl rearrangement of a protonated 3,3'-spiroindolenine was isolated and characterized by X-ray crystallography. These findings not only provide experimental support for Jiang's proposed biosynthesis of exotine A and exotine B but also foreshadow the existence of other exotine-derived natural products having isomeric frameworks. Exploratory attempts to induce an enantioselective 3CR using a chiral phosphoric acid were unsuccessful.
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Affiliation(s)
- Lance T Lepovitz
- Department of Chemistry and the Institute of Cellular and Molecular Biology, The University of Texas, Austin, Texas 78712, United States
| | - Stephen F Martin
- Department of Chemistry and the Institute of Cellular and Molecular Biology, The University of Texas, Austin, Texas 78712, United States
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Wood MD, Klosowski DW, Martin SF. Tandem vinylogous Mannich and hetero Diels-Alder reactions: Concise total synthesis of (±)-Alstoscholarisine E. Tetrahedron 2021. [DOI: 10.1016/j.tet.2021.132150] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022]
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Abeykoon GA, Sahn JJ, Martin SF. Novel substituted triazolo benzodiazepine scaffolds to explore chemical space. Tetrahedron Lett 2021. [DOI: 10.1016/j.tetlet.2021.152828] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022]
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12
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Cramer DL, Cheng B, Tian J, Clements JH, Wypych RM, Martin SF. Some thermodynamic effects of varying nonpolar surfaces in protein-ligand interactions. Eur J Med Chem 2020; 208:112771. [PMID: 32916312 DOI: 10.1016/j.ejmech.2020.112771] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/02/2020] [Revised: 08/11/2020] [Accepted: 08/15/2020] [Indexed: 12/18/2022]
Abstract
Understanding how making structural changes in small molecules affects their binding affinities for targeted proteins is central to improving strategies for rational drug design. To assess the effects of varying the nature of nonpolar groups upon binding entropies and enthalpies, we designed and prepared a set of Grb2-SH2 domain ligands, Ac-pTyr-Ac6c-Asn-(CH2)n-R, in which the size and electrostatic nature of R groups at the pTyr+3 site were varied. The complexes of these ligands with the Grb2-SH2 domain were evaluated in a series of studies in which the binding thermodynamics were determined using isothermal titration calorimetry, and binding interactions were examined in crystallographic studies of two different complexes. Notably, adding nonpolar groups to the pTyr+3 site leads to higher binding affinities, but the magnitude and energetic origins of these effects vary with the nature of the R substituent. For example, enhancements to binding affinities using aliphatic R groups are driven by more favorable changes in binding entropies, whereas aryl R groups improve binding free energies through a combination of more favorable changes in binding enthalpies and entropies. However, enthalpy/entropy compensation plays a significant role in these associations and mitigates against any significant variation in binding free energies, which vary by only 0.8 kcal•mol-1, with changes in the electrostatic nature and size of the R group. Crystallographic studies show that differences in ΔG° or ΔH° correlate with buried nonpolar surface area, but they do not correlate with the total number of polar or van der Waals contacts. The relative number of ordered water molecules and relative order in the side chains at pTyr+3 correlate with differences in -TΔS°. Overall, these studies show that burial of nonpolar surface can lead to enhanced binding affinities arising from dominating entropy- or enthalpy-driven hydrophobic effects, depending upon the electrostatic nature of the apolar R group.
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Affiliation(s)
- David L Cramer
- Department of Chemistry and the Institute of Cellular and Molecular Biology, The University of Texas, Austin, TX 78712, USA
| | - Bo Cheng
- Department of Chemistry and the Institute of Cellular and Molecular Biology, The University of Texas, Austin, TX 78712, USA
| | - Jianhua Tian
- Department of Chemistry and the Institute of Cellular and Molecular Biology, The University of Texas, Austin, TX 78712, USA
| | - John H Clements
- Department of Chemistry and the Institute of Cellular and Molecular Biology, The University of Texas, Austin, TX 78712, USA
| | - Rachel M Wypych
- Department of Chemistry and the Institute of Cellular and Molecular Biology, The University of Texas, Austin, TX 78712, USA
| | - Stephen F Martin
- Department of Chemistry and the Institute of Cellular and Molecular Biology, The University of Texas, Austin, TX 78712, USA.
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13
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Abstract
The first total syntheses of (±)-melicolones A and B, which have a unique and densely functionalized framework derived from a rearranged prenylated acetophenone, were accomplished in 12.3% combined overall yield. The concise and divergent synthesis of these two natural products, which were isolated in racemic form, was achieved in a longest linear sequence requiring only 9 steps (11 total steps) and 8 isolated intermediates using commercially available starting materials. This approach, which might enable access to all tetracyclic melicolones, features the highly regioselective (16:1) and diastereoselective (15:1) dipolar cycloaddition of a carbonyl ylide generated by the unusual cyclization of a rhodium carbene with the carbonyl oxygen atom of an aliphatic aldehyde. This cycloaddition proceeds with dominant steric control to give a highly functionalized oxabicycloheptane core. Stereoselective enolate alkylation led to a prenylated intermediate that underwent an intramolecular aldol reaction to give the penultimate tricyclic intermediate. Tandem epoxidation of the pendant prenyl group followed by a regioselective, acid-catalyzed cyclization delivered (±)-melicolones A and B.
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Affiliation(s)
- Zhipeng Wang
- Department of Chemistry, The University of Texas at Austin, Austin, Texas 78712, United States
| | - Stephen F Martin
- Department of Chemistry, The University of Texas at Austin, Austin, Texas 78712, United States
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Quadir SG, Tanino SM, Rohl CD, Sahn JJ, Yao EJ, Cruz LDR, Cottone P, Martin SF, Sabino V. The Sigma-2 receptor / transmembrane protein 97 (σ2R/TMEM97) modulator JVW-1034 reduces heavy alcohol drinking and associated pain states in male mice. Neuropharmacology 2020; 184:108409. [PMID: 33221481 DOI: 10.1016/j.neuropharm.2020.108409] [Citation(s) in RCA: 20] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/24/2020] [Revised: 10/27/2020] [Accepted: 11/17/2020] [Indexed: 12/15/2022]
Abstract
Alcohol Use Disorder (AUD) is a chronic relapsing disorder characterized by compulsive alcohol intake, loss of control over alcohol intake, and a negative emotional state when access to alcohol is prevented. AUD is also closely tied to pain, as repeated alcohol drinking leads to increased pain sensitivity during withdrawal. The sigma-2 receptor, recently identified as transmembrane protein 97 (σ2R/TMEM97), is an integral membrane protein involved in cholesterol homeostasis and lipid metabolism. Selective σ2R/Tmem97 modulators have been recently shown to relieve mechanical hypersensitivity in animal models of neuropathic pain as well as to attenuate alcohol withdrawal signs in C. elegans and to reduce alcohol drinking in rats, suggesting a potential key role for this protein in alcohol-related behaviors. In this study, we tested the effects of a potent and selective σ2R/TMEM97 ligand, JVW-1034, on heavy alcohol drinking and alcohol-induced heightened pain states in mice using an intermittent access model. Administration of JVW-1034 decreased both ethanol intake and preference for ethanol, without affecting water intake, total fluid intake, or food intake. Notably, this effect was specific for alcohol, as JVW-1034 had no effect on sucrose intake. Furthermore, JVW-1034 reduced both thermal hyperalgesia and mechanical hypersensitivity in ethanol withdrawn mice. Our data provide important evidence that modulation of σ2R/TMEM97 with small molecules can mediate heavy alcohol drinking as well as chronic alcohol-induced heightened pain sensitivity, thereby identifying a promising novel pharmacological target for AUD and associated pain states.
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Affiliation(s)
- Sema G Quadir
- Laboratory of Addictive Disorders, Departments of Pharmacology and Psychiatry, Boston University School of Medicine, 72 E. Concord St, Boston, MA, USA
| | - Sean M Tanino
- Laboratory of Addictive Disorders, Departments of Pharmacology and Psychiatry, Boston University School of Medicine, 72 E. Concord St, Boston, MA, USA
| | - Christian D Rohl
- Laboratory of Addictive Disorders, Departments of Pharmacology and Psychiatry, Boston University School of Medicine, 72 E. Concord St, Boston, MA, USA
| | - James J Sahn
- Department of Chemistry and Waggoner Center for Alcohol and Addiction Research, University of Texas at Austin, Austin, TX, USA
| | - Emily J Yao
- Laboratory of Addictive Disorders, Departments of Pharmacology and Psychiatry, Boston University School of Medicine, 72 E. Concord St, Boston, MA, USA
| | - Luíza Dos Reis Cruz
- Department of Chemistry and Waggoner Center for Alcohol and Addiction Research, University of Texas at Austin, Austin, TX, USA
| | - Pietro Cottone
- Laboratory of Addictive Disorders, Departments of Pharmacology and Psychiatry, Boston University School of Medicine, 72 E. Concord St, Boston, MA, USA
| | - Stephen F Martin
- Department of Chemistry and Waggoner Center for Alcohol and Addiction Research, University of Texas at Austin, Austin, TX, USA.
| | - Valentina Sabino
- Laboratory of Addictive Disorders, Departments of Pharmacology and Psychiatry, Boston University School of Medicine, 72 E. Concord St, Boston, MA, USA.
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Blumberg S, Martin SF. Racemic or enantioselective osmium-catalyzed dihydroxylation of olefins under near-neutral conditions. ARKIVOC 2020. [DOI: 10.24820/ark.5550190.p011.266] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022] Open
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16
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Wypych RM, LaPlante SR, White PW, Martin SF. Structure-thermodynamics-relationships of hepatitis C viral NS3 protease inhibitors. Eur J Med Chem 2020; 192:112195. [PMID: 32151833 DOI: 10.1016/j.ejmech.2020.112195] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/13/2019] [Revised: 02/10/2020] [Accepted: 02/26/2020] [Indexed: 02/06/2023]
Abstract
Thermodynamic parameters were determined for structurally-related inhibitors of HCV NS3 protease to assess how binding entropies and enthalpies vary with incremental changes at the P2 and P3 inhibitor subsites. Changing the heterocyclic substituent at P2 from a pyridyl to a 7-methoxy-2-phenyl-4-quinolyl group leads to a 710-fold increase in affinity. Annelating a benzene ring onto a pyridine ring leads to quinoline-derived inhibitors having higher affinities, but the individual enthalpy and entropy contributions are markedly different for each ligand pair. Introducing a phenyl group at C2 of the heterocyclic ring at P2 uniformly leads to higher affinity analogs with more favorable binding entropies, while adding a methoxy group at C7 of the quinoline ring at P2 provides derivatives with more favorable binding enthalpies. Significant enthalpy/entropy compensation is observed for structural changes made to inhibitors lacking a 2-phenyl substituent, whereas favorable changes in both binding enthalpies and entropies accompany structural modifications when a 2-phenyl group is present. Overall, binding energetics of inhibitors having a 2-phenyl-4-quinolyl group at P2 are dominated by entropic effects, whereas binding of the corresponding norphenyl analogs are primarily enthalpy driven. Notably, the reversal from an entropy driven association to an enthalpy driven one for this set of inhibitors also correlates with alternate binding modes. When the steric bulk of the side chain at P3 is increased from a hydrogen atom to a tert-butyl group, there is a 770-fold improvement in affinity. The 30-fold increase resulting from the first methyl group is solely the consequence of a more favorable change in entropy, whereas subsequent additions of methyl groups leads to modest increases in affinity that arise primarily from incremental improvements in binding enthalpies accompanied with smaller favorable entropic contributions.
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Affiliation(s)
- Rachel M Wypych
- The University of Texas at Austin, Department of Chemistry, 105 E 24th St Station A5300, Austin, TX, 78712-1224, USA
| | - Steven R LaPlante
- Université du Québec, INRS-Centre Armand Frappier Santé et Biotechnologie, 531 Boulevard des Prairies, Laval, QC, H7V 1B7, Canada.
| | - Peter W White
- Boehringer Ingelheim (Canada) Limited, Research and Development, 2100 rue Cunard, Laval, Quebec, H7S 2G5, Canada
| | - Stephen F Martin
- The University of Texas at Austin, Department of Chemistry, 105 E 24th St Station A5300, Austin, TX, 78712-1224, USA.
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18
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Affiliation(s)
- Michael D. Wood
- Department of Chemistry, The University of Texas at Austin, Austin, Texas 78712, United States
| | - Daniel W. Klosowski
- Department of Chemistry, The University of Texas at Austin, Austin, Texas 78712, United States
| | - Stephen F. Martin
- Department of Chemistry, The University of Texas at Austin, Austin, Texas 78712, United States
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Widmer W, Brause A, Coppola E, Daniels K, Feicht R, Hendricks S, Kirksey ST, Kline LL, Krueger D, Martin SF, Matos J, Metcalf L, Nolan S, Smith C, Smith R, Trama T. Determination of Naringin and Neohesperidin in Orange Juice by Liquid Chromatography with UV Detection to Detect the Presence of Grapefruit Juice: Collaborative Study. J AOAC Int 2019. [DOI: 10.1093/jaoac/83.5.1155] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
Abstract
Fifteen collaborating laboratories were sent 9 samples of citrus juice mixtures as blind duplicates for determination of naringin and neohesperidin by liquid chromatography. Two sample pairs were 100% orange juice and did not contain any naringin or neohesperidin. The remaining 7 sample pairs contained naringin at levels ranging from 3.9 to 46.5 ppm and neohesperidin at levels ranging from 0.14 to 35.6 ppm. Five sample pairs consisted of orange juice mixtures containing 1, 3, and 5% grapefruit juice; 5% sour orange; and 5% K-Early citrus variety. Two sample pairs were orange juice spiked with naringin, neohesperidin, sodium benzoate, and potassium sorbate. Data were received from 13 laboratories. Data from 1 collaborator were eliminated because the method protocol was not followed. Neohesperidin values from another laboratory were also not used because of problems with a coeluting component. Repeatability relative standard deviations ranged from 2.95 to 15.23% for naringin and from 3.00 to 11.74% for neohesperidin. Reproducibility relative standard deviations ranged from 11.34 to 31.94% for naringin and from 10.45 to 26.17% for neohesperidin. The method is reliable for detecting the presence of grapefruit juice in orange juice as indicated by a finding of ≥10 ppm naringin and ≤2 ppm neohesperidin. The method was adopted First Action by AOAC INTERNATIONAL.
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Affiliation(s)
- Wilbur Widmer
- Florida Department of Citrus, Citrus Research and Education Center, 700 Experiment Station Rd, Lake Alfred, FL 33850
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20
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21
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Sabino V, Quadir SG, Tanino SM, Rohl CD, Sahn JJ, Moore CF, Martin SF, Cottone P. Opposing roles of Sigma‐1 and Sigma‐2 receptors in heavy alcohol drinking and associated mechanical allodynia in mice. FASEB J 2019. [DOI: 10.1096/fasebj.2019.33.1_supplement.499.8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Affiliation(s)
- Valentina Sabino
- Pharmacology and PsychiatryBoston University School of MedicineBostonMA
| | - Sema G Quadir
- Pharmacology and PsychiatryBoston University School of MedicineBostonMA
| | - Sean M Tanino
- Pharmacology and PsychiatryBoston University School of MedicineBostonMA
| | - Christian D Rohl
- Pharmacology and PsychiatryBoston University School of MedicineBostonMA
| | | | - Catherine F Moore
- Pharmacology and PsychiatryBoston University School of MedicineBostonMA
| | | | - Pietro Cottone
- Pharmacology and PsychiatryBoston University School of MedicineBostonMA
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22
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Vázquez-Rosa E, Watson MR, Sahn JJ, Hodges TR, Schroeder RE, Cintrón-Pérez CJ, Shin MK, Yin TC, Emery JL, Martin SF, Liebl DJ, Pieper AA. Neuroprotective Efficacy of a Sigma 2 Receptor/TMEM97 Modulator (DKR-1677) after Traumatic Brain Injury. ACS Chem Neurosci 2019; 10:1595-1602. [PMID: 30421909 DOI: 10.1021/acschemneuro.8b00543] [Citation(s) in RCA: 42] [Impact Index Per Article: 8.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022] Open
Abstract
Compounds targeting the sigma 2 receptor, which we recently cloned and showed to be identical with transmembrane protein 97 (σ2R/TMEM97), are broadly applicable therapeutic agents currently in clinical trials for imaging in breast cancer and for treatment of Alzheimer's disease and schizophrenia. These promising applications coupled with our previous observation that the σ2R/TMEM97 modulator SAS-0132 has neuroprotective attributes and improves cognition in wild-type mice suggests that modulating σ2R/TMEM97 may also have therapeutic benefits in other neurodegenerative conditions such as traumatic brain injury (TBI). Herein, we report that DKR-1677, a novel derivative of SAS-0132 with increased affinity and selectivity for σ2R/Tmem97 ( Ki = 5.1 nM), is neuroprotective after blast-induced and controlled cortical impact (CCI) TBI in mice. Specifically, we discovered that treatment with DKR-1677 decreases axonal degeneration after blast-induced TBI and enhances survival of cortical neurons and oligodendrocytes after CCI injury. Furthermore, treatment with DKR-1677 preserves cognition in the Morris water maze after blast TBI. Our results support an increasingly broad role for σ2R/Tmem97 modulation in neuroprotection and suggest a new approach for treating patients suffering from TBI.
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Affiliation(s)
- Edwin Vázquez-Rosa
- Department of Psychiatry and Department of Free Radical, Radiation Biology Program, Holden Comprehensive Cancer Center, University of Iowa Carver College of Medicine, Iowa City, Iowa 52242, United States
- Department of Psychiatry Case Western Reserve University, Geriatric Research Education and Clinical Centers, Harrington Discovery Institute, University Hospital, Case Medical Center, Louis Stokes Cleveland VAMC, Cleveland, Ohio 44106, United States
| | - Michael R. Watson
- The Miami Project to Cure Paralysis, Department of Neurological Surgery, University of Miami Miller School of Medicine, Miami, Florida 33136, United States
| | - James J. Sahn
- Department of Chemistry, The University of Texas at Austin, Austin, Texas 78712, United States
| | - Timothy R. Hodges
- Department of Chemistry, The University of Texas at Austin, Austin, Texas 78712, United States
| | - Rachel E. Schroeder
- Department of Psychiatry and Department of Free Radical, Radiation Biology Program, Holden Comprehensive Cancer Center, University of Iowa Carver College of Medicine, Iowa City, Iowa 52242, United States
| | - Coral J. Cintrón-Pérez
- Department of Psychiatry Case Western Reserve University, Geriatric Research Education and Clinical Centers, Harrington Discovery Institute, University Hospital, Case Medical Center, Louis Stokes Cleveland VAMC, Cleveland, Ohio 44106, United States
| | - Min-Kyoo Shin
- Department of Psychiatry Case Western Reserve University, Geriatric Research Education and Clinical Centers, Harrington Discovery Institute, University Hospital, Case Medical Center, Louis Stokes Cleveland VAMC, Cleveland, Ohio 44106, United States
| | - Terry C. Yin
- Department of Psychiatry and Department of Free Radical, Radiation Biology Program, Holden Comprehensive Cancer Center, University of Iowa Carver College of Medicine, Iowa City, Iowa 52242, United States
| | - Josie L. Emery
- Department of Psychiatry and Department of Free Radical, Radiation Biology Program, Holden Comprehensive Cancer Center, University of Iowa Carver College of Medicine, Iowa City, Iowa 52242, United States
| | - Stephen F. Martin
- Department of Chemistry, The University of Texas at Austin, Austin, Texas 78712, United States
| | - Daniel J. Liebl
- The Miami Project to Cure Paralysis, Department of Neurological Surgery, University of Miami Miller School of Medicine, Miami, Florida 33136, United States
| | - Andrew A. Pieper
- Department of Psychiatry and Department of Free Radical, Radiation Biology Program, Holden Comprehensive Cancer Center, University of Iowa Carver College of Medicine, Iowa City, Iowa 52242, United States
- Department of Psychiatry Case Western Reserve University, Geriatric Research Education and Clinical Centers, Harrington Discovery Institute, University Hospital, Case Medical Center, Louis Stokes Cleveland VAMC, Cleveland, Ohio 44106, United States
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Abstract
Exotine A, which comprises an unusual coumarin-cyclohepta[ b]indole ring system, has been synthesized for the first time in a one-pot process from known starting materials. The key step features a biomimetically inspired combination of three components to deliver exotine A and 11'- epi-exotine A in 43% yield and 17:1 diastereomeric ratio. Some mechanistic aspects of this reaction are discussed.
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Affiliation(s)
- Lance T Lepovitz
- Department of Molecular Biosciences , The University of Texas at Austin , Austin , Texas 78712 , United States
| | - Stephen F Martin
- Department of Chemistry , The University of Texas at Austin , Austin , Texas 78712 , United States
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Klosowski DW, Hethcox JC, Paull DH, Fang C, Donald JR, Shugrue CR, Pansick AD, Martin SF. Enantioselective Halolactonization Reactions using BINOL-Derived Bifunctional Catalysts: Methodology, Diversification, and Applications. J Org Chem 2018; 83:5954-5968. [PMID: 29717607 PMCID: PMC5984189 DOI: 10.1021/acs.joc.8b00490] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
A general protocol is described for inducing enantioselective halolactonizations of unsaturated carboxylic acids using novel bifunctional organic catalysts derived from a chiral binaphthalene scaffold. Bromo- and iodolactonization reactions of diversely substituted, unsaturated carboxylic acids proceed with high degrees of enantioselectivity, regioselectivity, and diastereoselectivity. Notably, these BINOL-derived catalysts are the first to induce the bromo- and iodolactonizations of 5-alkyl-4( Z)-olefinic acids via 5- exo mode cyclizations to give lactones in which new carbon-halogen bonds are created at a stereogenic center with high diastereo- and enantioselectivities. Iodolactonizations of 6-substituted-5( Z)-olefinic acids also occur via 6- exo cyclizations to provide δ-lactones with excellent enantioselectivities. Several notable applications of this halolactonization methodology were developed for desymmetrization, kinetic resolution, and epoxidation of Z-alkenes. The utility of these reactions is demonstrated by their application to a synthesis of precursors of the F-ring subunit of kibdelone C and to the shortest catalytic, enantioselective synthesis of (+)-disparlure reported to date.
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Affiliation(s)
- Daniel W. Klosowski
- Department of Chemistry, The University of Texas at Austin, Austin, Texas 78712
| | - J. Caleb Hethcox
- Department of Chemistry, The University of Texas at Austin, Austin, Texas 78712
| | | | | | | | | | - Andrew D. Pansick
- Department of Chemistry, The University of Texas at Austin, Austin, Texas 78712
| | - Stephen F. Martin
- Department of Chemistry, The University of Texas at Austin, Austin, Texas 78712
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Mondal S, Hegarty E, Sahn JJ, Scott LL, Gökçe SK, Martin C, Ghorashian N, Satarasinghe PN, Iyer S, Sae-Lee W, Hodges TR, Pierce JT, Martin SF, Ben-Yakar A. High-Content Microfluidic Screening Platform Used To Identify σ2R/Tmem97 Binding Ligands that Reduce Age-Dependent Neurodegeneration in C. elegans SC_APP Model. ACS Chem Neurosci 2018; 9:1014-1026. [PMID: 29426225 DOI: 10.1021/acschemneuro.7b00428] [Citation(s) in RCA: 20] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
The nematode Caenorhabditis elegans, with tractable genetics and a well-defined nervous system, provides a unique whole-animal model system to identify novel drug targets and therapies for neurodegenerative diseases. Large-scale drug or target screens in models that recapitulate the subtle age- and cell-specific aspects of neurodegenerative diseases are limited by a technological requirement for high-throughput analysis of neuronal morphology. Recently, we developed a single-copy model of amyloid precursor protein (SC_APP) induced neurodegeneration that exhibits progressive degeneration of select cholinergic neurons. Our previous work with this model suggests that small molecule ligands of the sigma 2 receptor (σ2R), which was recently cloned and identified as transmembrane protein 97 (TMEM97), are neuroprotective. To determine structure-activity relationships for unexplored chemical space in our σ2R/Tmem97 ligand collection, we developed an in vivo high-content screening (HCS) assay to identify potential drug leads. The HCS assay uses our recently developed large-scale microfluidic immobilization chip and automated imaging platform. We discovered norbenzomorphans that reduced neurodegeneration in our C. elegans model, including two compounds that demonstrated significant neuroprotective activity at multiple doses. These findings provide further evidence that σ2R/Tmem97-binding norbenzomorphans may represent a new drug class for treating neurodegenerative diseases.
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Klosowski DW, Martin SF. Correction to “Synthesis of (+)-Disparlure via Enantioselective Iodolactonization”. Org Lett 2018; 20:2796. [DOI: 10.1021/acs.orglett.8b00999] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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Linkens K, Schmidt HR, Sahn JJ, Kruse AC, Martin SF. Investigating isoindoline, tetrahydroisoquinoline, and tetrahydrobenzazepine scaffolds for their sigma receptor binding properties. Eur J Med Chem 2018; 151:557-567. [DOI: 10.1016/j.ejmech.2018.02.024] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/02/2018] [Revised: 02/07/2018] [Accepted: 02/08/2018] [Indexed: 12/13/2022]
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Dockendorff C, Gandhi DM, Kimball IH, Eum KS, Rusinova R, Ingólfsson HI, Kapoor R, Peyear T, Dodge MW, Martin SF, Aldrich RW, Andersen OS, Sack JT. Synthetic Analogues of the Snail Toxin 6-Bromo-2-mercaptotryptamine Dimer (BrMT) Reveal That Lipid Bilayer Perturbation Does Not Underlie Its Modulation of Voltage-Gated Potassium Channels. Biochemistry 2018; 57:2733-2743. [PMID: 29616558 PMCID: PMC6007853 DOI: 10.1021/acs.biochem.8b00292] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Abstract
Drugs do not act solely by canonical ligand-receptor binding interactions. Amphiphilic drugs partition into membranes, thereby perturbing bulk lipid bilayer properties and possibly altering the function of membrane proteins. Distinguishing membrane perturbation from more direct protein-ligand interactions is an ongoing challenge in chemical biology. Herein, we present one strategy for doing so, using dimeric 6-bromo-2-mercaptotryptamine (BrMT) and synthetic analogues. BrMT is a chemically unstable marine snail toxin that has unique effects on voltage-gated K+ channel proteins, making it an attractive medicinal chemistry lead. BrMT is amphiphilic and perturbs lipid bilayers, raising the question of whether its action against K+ channels is merely a manifestation of membrane perturbation. To determine whether medicinal chemistry approaches to improve BrMT might be viable, we synthesized BrMT and 11 analogues and determined their activities in parallel assays measuring K+ channel activity and lipid bilayer properties. Structure-activity relationships were determined for modulation of the Kv1.4 channel, bilayer partitioning, and bilayer perturbation. Neither membrane partitioning nor bilayer perturbation correlates with K+ channel modulation. We conclude that BrMT's membrane interactions are not critical for its inhibition of Kv1.4 activation. Further, we found that alkyl or ether linkages can replace the chemically labile disulfide bond in the BrMT pharmacophore, and we identified additional regions of the scaffold that are amenable to chemical modification. Our work demonstrates a strategy for determining if drugs act by specific interactions or bilayer-dependent mechanisms, and chemically stable modulators of Kv1 channels are reported.
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Affiliation(s)
- Chris Dockendorff
- Department of Chemistry , Marquette University , P.O. Box 1881, Milwaukee , Wisconsin 53201-1881 , United States
| | - Disha M Gandhi
- Department of Chemistry , Marquette University , P.O. Box 1881, Milwaukee , Wisconsin 53201-1881 , United States
| | - Ian H Kimball
- Department of Physiology & Membrane Biology , University of California , 1 Shields Avenue , Davis , California 95616 , United States
| | - Kenneth S Eum
- Department of Physiology & Membrane Biology , University of California , 1 Shields Avenue , Davis , California 95616 , United States
| | - Radda Rusinova
- Department of Physiology and Biophysics , Weill Cornell Medical College , New York , New York 10065 , United States
| | - Helgi I Ingólfsson
- Department of Physiology and Biophysics , Weill Cornell Medical College , New York , New York 10065 , United States
| | - Ruchi Kapoor
- Department of Physiology and Biophysics , Weill Cornell Medical College , New York , New York 10065 , United States
| | - Thasin Peyear
- Department of Physiology and Biophysics , Weill Cornell Medical College , New York , New York 10065 , United States
| | - Matthew W Dodge
- Department of Chemistry , Marquette University , P.O. Box 1881, Milwaukee , Wisconsin 53201-1881 , United States
| | - Stephen F Martin
- Department of Chemistry , University of Texas at Austin , 1 University Station , Austin , Texas 78712 , United States
| | - Richard W Aldrich
- Department of Neuroscience , University of Texas at Austin , 1 University Station , Austin , Texas 78712 , United States
| | - Olaf S Andersen
- Department of Physiology and Biophysics , Weill Cornell Medical College , New York , New York 10065 , United States
| | - Jon T Sack
- Department of Physiology & Membrane Biology , University of California , 1 Shields Avenue , Davis , California 95616 , United States
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31
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Abstract
The BINOL-amidine organic catalyst 1 was previously shown to promote highly efficient enantioselective halolactonization reactions of olefinic acids. As part of these studies, it was discovered that the enantioenriched iodolactones could be easily converted into enantioenriched cis-1,2-disubstituted epoxides. This halolactonization-epoxidation sequence was applied to the synthesis of (+)-disparlure, which resulted in the shortest catalytic enantioselective synthesis to date, requiring only five steps and proceeding in 33% yield.
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Affiliation(s)
- Daniel W. Klosowski
- Department of Chemistry, The University of Texas at Austin, Austin, Texas 78712
| | - Stephen F. Martin
- Department of Chemistry, The University of Texas at Austin, Austin, Texas 78712
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32
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Abstract
Diverse structural types of natural products and their mimics have served as targets of opportunity in our laboratory to inspire the discovery and development of new methods and strategies to assemble polyfunctional and polycyclic molecular architectures. Furthermore, our efforts toward identifying novel compounds having useful biological properties led to the creation of new targets, many of which posed synthetic challenges that required the invention of new methodology. In this Perspective, selected examples of how we have exploited a diverse range of natural products and their mimics to create, explore, and solve a variety of problems in chemistry and biology will be discussed. The journey was not without its twists and turns, but the unexpected often led to new revelations and insights. Indeed, in our recent excursion into applications of synthetic organic chemistry to neuroscience, avoiding the more-traveled paths was richly rewarding.
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Affiliation(s)
- Stephen F Martin
- Department of Chemistry, The University of Texas at Austin , Austin, Texas 78712, United States
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33
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Abstract
Neuropathic pain is an important medical problem with few effective treatments. The sigma 1 receptor (σ1R) is known to be a potential target for neuropathic pain therapeutics, and antagonists for this receptor are effective in preclinical models and are currently in phase II clinical trials. Conversely, relatively little is known about σ2R, which has recently been identified as transmembrane protein 97 (Tmem97). We generated a series of σ1R and σ2R/Tmem97 agonists and antagonists and tested them for efficacy in the mouse spared nerve injury (SNI) model. In agreement with previous reports, we find that σ1R ligands given intrathecally (IT) produce relief of SNI-induced mechanical hypersensitivity. We also find that the putative σ2R/Tmem97 agonists DKR-1005, DKR-1051, and UKH-1114 (Ki ∼ 46 nM) lead to relief of SNI-induced mechanical hypersensitivity, peaking at 48 h after dosing when given IT. This effect is blocked by the putative σ2R/Tmem97 antagonist SAS-0132. Systemic administration of UKH-1114 (10 mg/kg) relieves SNI-induced mechanical hypersensitivity for 48 h with a peak magnitude of effect equivalent to 100 mg/kg gabapentin and without producing any motor impairment. Finally, we find that the TMEM97 gene is expressed in mouse and human dorsal root ganglion (DRG) including populations of neurons that are involved in pain; however, the gene is also likely expressed in non-neuronal cells that may contribute to the observed behavioral effects. Our results show robust antineuropathic pain effects of σ1R and σ2R/Tmem97 ligands, demonstrate that σ2R/Tmem97 is a novel neuropathic pain target, and identify UKH-1114 as a lead molecule for further development.
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MESH Headings
- Amines/pharmacology
- Analgesics, Opioid/chemistry
- Analgesics, Opioid/pharmacology
- Animals
- Cyclohexanecarboxylic Acids/pharmacology
- Disease Models, Animal
- Gabapentin
- Ganglia, Spinal/drug effects
- Ganglia, Spinal/metabolism
- Humans
- Hyperalgesia/drug therapy
- Hyperalgesia/metabolism
- Male
- Membrane Proteins/metabolism
- Mice, Inbred C57BL
- Molecular Structure
- Motor Activity/drug effects
- Neuralgia/drug therapy
- Neuralgia/metabolism
- RNA, Messenger/metabolism
- Receptors, sigma/agonists
- Receptors, sigma/antagonists & inhibitors
- Receptors, sigma/metabolism
- Touch
- gamma-Aminobutyric Acid/pharmacology
- Sigma-1 Receptor
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Affiliation(s)
- James J. Sahn
- Department of Chemistry and Biochemistry, The University of Texas at Austin, Austin, Texas 78712, United States
| | - Galo L. Mejia
- School of Behavioral and Brain Sciences, The University of Texas at Dallas, Richardson, Texas 75080, United States
| | - Pradipta R. Ray
- School of Behavioral and Brain Sciences, The University of Texas at Dallas, Richardson, Texas 75080, United States
| | - Stephen F. Martin
- Department of Chemistry and Biochemistry, The University of Texas at Austin, Austin, Texas 78712, United States
| | - Theodore J. Price
- School of Behavioral and Brain Sciences, The University of Texas at Dallas, Richardson, Texas 75080, United States
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34
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Yi B, Sahn JJ, Ardestani PM, Evans AK, Scott LL, Chan JZ, Iyer S, Crisp A, Zuniga G, Pierce JT, Martin SF, Shamloo M. Small molecule modulator of sigma 2 receptor is neuroprotective and reduces cognitive deficits and neuroinflammation in experimental models of Alzheimer's disease. J Neurochem 2017; 140:561-575. [PMID: 27926996 DOI: 10.1111/jnc.13917] [Citation(s) in RCA: 84] [Impact Index Per Article: 12.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/19/2016] [Revised: 11/23/2016] [Accepted: 12/01/2016] [Indexed: 12/29/2022]
Abstract
Accumulating evidence suggests that modulating the sigma 2 receptor (Sig2R) can provide beneficial effects for neurodegenerative diseases. Herein, we report the identification of a novel class of Sig2R ligands and their cellular and in vivo activity in experimental models of Alzheimer's disease (AD). We report that SAS-0132 and DKR-1051, selective ligands of Sig2R, modulate intracellular Ca2+ levels in human SK-N-SH neuroblastoma cells. The Sig2R ligands SAS-0132 and JVW-1009 are neuroprotective in a C. elegans model of amyloid precursor protein-mediated neurodegeneration. Since this neuroprotective effect is replicated by genetic knockdown and knockout of vem-1, the ortholog of progesterone receptor membrane component-1 (PGRMC1), these results suggest that Sig2R ligands modulate a PGRMC1-related pathway. Last, we demonstrate that SAS-0132 improves cognitive performance both in the Thy-1 hAPPLond/Swe+ transgenic mouse model of AD and in healthy wild-type mice. These results demonstrate that Sig2R is a promising therapeutic target for neurocognitive disorders including AD.
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Affiliation(s)
- Bitna Yi
- Department of Neurosurgery, Stanford University School of Medicine, Palo Alto, California, USA
| | - James J Sahn
- Department of Chemistry, The University of Texas at Austin, Austin, Texas, USA
| | - Pooneh Memar Ardestani
- Department of Neurosurgery, Stanford University School of Medicine, Palo Alto, California, USA
| | - Andrew K Evans
- Department of Neurosurgery, Stanford University School of Medicine, Palo Alto, California, USA
| | - Luisa L Scott
- Waggoner Center for Alcohol and Addiction Research, Institute of Neuroscience, Center for Learning and Memory, Center for Brain, Behavior and Evolution and Department of Neuroscience, The University of Texas at Austin, Austin, Texas, USA
| | - Jessica Z Chan
- Department of Chemistry, The University of Texas at Austin, Austin, Texas, USA
| | - Sangeetha Iyer
- Waggoner Center for Alcohol and Addiction Research, Institute of Neuroscience, Center for Learning and Memory, Center for Brain, Behavior and Evolution and Department of Neuroscience, The University of Texas at Austin, Austin, Texas, USA
| | - Ashley Crisp
- Waggoner Center for Alcohol and Addiction Research, Institute of Neuroscience, Center for Learning and Memory, Center for Brain, Behavior and Evolution and Department of Neuroscience, The University of Texas at Austin, Austin, Texas, USA
| | - Gabriella Zuniga
- Waggoner Center for Alcohol and Addiction Research, Institute of Neuroscience, Center for Learning and Memory, Center for Brain, Behavior and Evolution and Department of Neuroscience, The University of Texas at Austin, Austin, Texas, USA
| | - Jonathan T Pierce
- Waggoner Center for Alcohol and Addiction Research, Institute of Neuroscience, Center for Learning and Memory, Center for Brain, Behavior and Evolution and Department of Neuroscience, The University of Texas at Austin, Austin, Texas, USA
| | - Stephen F Martin
- Department of Chemistry, The University of Texas at Austin, Austin, Texas, USA
| | - Mehrdad Shamloo
- Department of Neurosurgery, Stanford University School of Medicine, Palo Alto, California, USA
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35
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Abstract
The σ2 receptor is an enigmatic protein that has attracted significant attention because of its involvement in diseases as diverse as cancer and neurological disorders. Unlike virtually all other receptors of medical interest, it has eluded molecular cloning since its discovery, and the gene that codes for the receptor remains unknown, precluding the use of modern biological methods to study its function. Using a chemical biology approach, we purified the σ2 receptor from tissue, revealing its identity as TMEM97, an endoplasmic reticulum-resident transmembrane protein that regulates the sterol transporter NPC1. We show that TMEM97 possesses the full suite of molecular properties that define the σ2 receptor, and we identify Asp29 and Asp56 as essential for ligand recognition. Cloning the σ2 receptor resolves a longstanding mystery and will enable therapeutic targeting of this potential drug target.
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Affiliation(s)
- Assaf Alon
- Department of Biological Chemistry and Molecular Pharmacology, Harvard Medical School, Boston, MA 02115
| | - Hayden R Schmidt
- Department of Biological Chemistry and Molecular Pharmacology, Harvard Medical School, Boston, MA 02115
| | - Michael D Wood
- Department of Chemistry, The University of Texas at Austin, Austin, TX 78712
| | - James J Sahn
- Department of Chemistry, The University of Texas at Austin, Austin, TX 78712
| | - Stephen F Martin
- Department of Chemistry, The University of Texas at Austin, Austin, TX 78712
| | - Andrew C Kruse
- Department of Biological Chemistry and Molecular Pharmacology, Harvard Medical School, Boston, MA 02115;
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36
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Affiliation(s)
| | | | - Stephen F. Martin
- Department
of Chemistry, The University of Texas, Austin, Texas 78712, United States
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37
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Sahn JJ, Hodges TR, Chan JZ, Martin SF. Norbenzomorphan Scaffold: Chemical Tool for Modulating Sigma Receptor-Subtype Selectivity. ACS Med Chem Lett 2017; 8:455-460. [PMID: 28435536 DOI: 10.1021/acsmedchemlett.7b00066] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/15/2017] [Accepted: 03/21/2017] [Indexed: 01/11/2023] Open
Abstract
Some norbenzomorphans exhibit high affinity for sigma 1 and sigma 2 receptors, and varying the position of substituents on the aromatic ring of this scaffold has a significant effect on subtype selectivity. In particular, compounds bearing several different substituents at C7 of the norbenzomorphan ring system exhibit a general preference for the sigma 1 receptor, whereas the corresponding C8-substituted analogues preferentially bind at the sigma 2 receptor. These findings suggest that the norbenzomorphan scaffold may be a unique chemical template that can be easily tuned to prepare small molecules for use as tool compounds to study the specific biological effects arising from preferential binding at either sigma receptor subtype. In the absence of structural characterization data for the sigma 2 receptor, such compounds will be useful toward refining the pharmacophore model of its binding site.
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Affiliation(s)
- James J. Sahn
- Department of Chemistry, The University of Texas at Austin, Austin, Texas 78712, United States
| | - Timothy R. Hodges
- Department of Chemistry, The University of Texas at Austin, Austin, Texas 78712, United States
| | - Jessica Z. Chan
- Department of Chemistry, The University of Texas at Austin, Austin, Texas 78712, United States
| | - Stephen F. Martin
- Department of Chemistry, The University of Texas at Austin, Austin, Texas 78712, United States
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38
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Affiliation(s)
- Rongrong Yu
- State
Key Laboratory of Chemical Resource Engineering, Department of Organic
Chemistry, College of Science, Beijing University of Chemical Technology, Beijing 100029, China
| | - Xingyu Chen
- State
Key Laboratory of Chemical Resource Engineering, Department of Organic
Chemistry, College of Science, Beijing University of Chemical Technology, Beijing 100029, China
| | - Stephen F. Martin
- Department
of Chemistry, University of Texas at Austin, Austin, Texas 78712, United States
| | - Zhiqian Wang
- State
Key Laboratory of Chemical Resource Engineering, Department of Organic
Chemistry, College of Science, Beijing University of Chemical Technology, Beijing 100029, China
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39
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Abstract
The citreamicins comprise a novel class of polycyclic xanthone natural products that have not yet yielded to total synthesis. A concise 11-step synthesis of the pentacyclic core of citreamicin η is now reported that features the use of a general approach for the synthesis of 1,4-dioxygenated xanthones. The synthesis also showcases improved techniques for effecting regioselective bromination of certain substituted phenols and coupling of acetylides with hindered ketones.
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Affiliation(s)
- Shawn Blumberg
- Department of Chemistry, University of Texas at Austin , Austin, Texas 78712, United States
| | - Stephen F Martin
- Department of Chemistry, University of Texas at Austin , Austin, Texas 78712, United States
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40
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Sahn JJ, Hodges TR, Chan JZ, Martin SF. Norbenzomorphan Framework as a Novel Scaffold for Generating Sigma 2 Receptor/PGRMC1 Subtype-Selective Ligands. ChemMedChem 2016; 11:556-61. [PMID: 26915462 PMCID: PMC4811364 DOI: 10.1002/cmdc.201500551] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/24/2015] [Revised: 01/12/2016] [Indexed: 12/20/2022]
Abstract
A novel structural class with high affinity and subtype selectivity for the sigma 2 receptor has been discovered. Preliminary structure-affinity relationship data are presented showing that 8-substituted 1,3,4,5-tetrahydro-1,5-methanobenzazepine (norbenzomorphan) derivatives elicit modest to high selectivity for the sigma 2 over the sigma 1 receptor subtype. Indeed, piperazine analogue 8-(4-(3-ethoxy-3-oxopropyl)piperazin-1-yl)-1,3,4,5-tetrahydro-1,5-methanobenzazepine-2-carboxylate (SAS-1121) is 574-fold selective for the sigma 2 over the sigma 1 receptor, thereby establishing it as one of the more subtype-selective sigma 2 binding ligands reported to date. Emerging evidence has implicated the sigma 2 receptor in multiple health disorders, so the drug-like characteristics of many of the selective sigma 2 receptor ligands disclosed herein, coupled with their structural similarity to frameworks found in known drugs, suggest that norbenzomorphan analogues may be promising candidates for further development into drug leads.
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Affiliation(s)
- James J Sahn
- Department of Chemistry, University of Texas at Austin, 105 East 24th Street, Stop A5300, Austin, TX, 78712, USA
| | - Timothy R Hodges
- Department of Chemistry, University of Texas at Austin, 105 East 24th Street, Stop A5300, Austin, TX, 78712, USA
| | - Jessica Z Chan
- Department of Chemistry, University of Texas at Austin, 105 East 24th Street, Stop A5300, Austin, TX, 78712, USA
| | - Stephen F Martin
- Department of Chemistry, University of Texas at Austin, 105 East 24th Street, Stop A5300, Austin, TX, 78712, USA.
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41
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Hethcox JC, Shanahan CS, Martin SF. Diastereoselective addition of monoorganocuprates to a chiral fumarate: reaction development and synthesis of (-)-dihydroprotolichesterinic acid. Tetrahedron 2015; 71:6361-6368. [PMID: 26273115 PMCID: PMC4528386 DOI: 10.1016/j.tet.2015.05.023] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
Recent studies of diastereoselective conjugate additions of monoorganocuprates, Li[RCuI], to chiral γ-alkoxycrotonates and fumarates are disclosed. This methodology was applied to the shortest total synthesis of (-)-dihydroprotolichesterinic acid to date, but several attempts to prepare other succinate-derived natural products, such as pilocarpine and antrodin E, were unsuccessful.
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Affiliation(s)
- J. Caleb Hethcox
- Department of Chemistry, The University of Texas at Austin, 1 University Station A5300, Austin, Texas 78712-0165, USA
| | - Charles S. Shanahan
- Department of Chemistry, The University of Texas at Austin, 1 University Station A5300, Austin, Texas 78712-0165, USA
| | - Stephen F. Martin
- Department of Chemistry, The University of Texas at Austin, 1 University Station A5300, Austin, Texas 78712-0165, USA
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42
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Martin SF. The 2014 Tetrahedron Prize for Creativity in Organic Chemistry. Tetrahedron 2015. [DOI: 10.1016/j.tet.2015.06.089] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
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43
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Martin SF. The 2014 Tetrahedron Prize for Creativity in Organic Chemistry. Tetrahedron 2015. [DOI: 10.1016/j.tet.2015.06.043] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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44
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Abstract
A novel approach to the Aspidosperma family of alkaloids was developed and applied to a concise total synthesis of (±)-pseudotabersonine that was accomplished in 11 steps. Key transformations include a stepwise variant of a Mannich-like multicomponent assembly process, a double ring-closing metathesis sequence, and a one-pot deprotection/cyclization reaction.
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Affiliation(s)
- Bo Cheng
- Department of Chemistry, The University of Texas at Austin, Austin, TX 78712
| | - James D Sunderhaus
- Department of Chemistry, The University of Texas at Austin, Austin, TX 78712
| | - Stephen F Martin
- Department of Chemistry, The University of Texas at Austin, Austin, TX 78712
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45
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Blumberg S, Martin SF. 4-(Phenylazo)diphenylamine (PDA): a universal indicator for the colorimetric titration of strong bases, Lewis acids, and hydride reducing agents. Tetrahedron Lett 2015. [DOI: 10.1016/j.tetlet.2015.02.068] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/24/2022]
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46
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Csepregi JZ, Németh T, Weber FC, Martin SF, Mócsai A. A2.27 The role of SYK in contact hypersensitivity. Ann Rheum Dis 2015. [DOI: 10.1136/annrheumdis-2015-207259.62] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/04/2022]
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47
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Yang J, Knueppel D, Cheng B, Mans D, Martin SF. Approaches to polycyclic 1,4-dioxygenated xanthones. Application to total synthesis of the aglycone of IB-00208. Org Lett 2014; 17:114-7. [PMID: 25513888 PMCID: PMC4285456 DOI: 10.1021/ol503336t] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
![]()
Hexacyclic xanthone natural products
such as IB-00208 present a formidable challenge in organic synthesis.
A new approach to polycyclic 1,4-dioxygenated xanthones from benzocyclobutenones
has been developed and applied to the first total synthesis of the
aglycone of IB-00208. The 22-step synthesis features an acetylide
stitching process that joins an aryl aldehyde with an angularly fused
benzocyclobutenone, which was prepared by a ring-closing
metathesis reaction. The resulting acetylenic benzocyclobutenone
diol underwent a Moore rearrangement to give an intermediate that
was further elaborated to the aglycone of IB-00208 as a mixture of
hydroquinone–quinone tautomers.
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Affiliation(s)
- Jingyue Yang
- Department of Chemistry, University of Texas at Austin , Austin, Texas 78712, United States
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48
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Sahn JJ, Granger BA, Martin SF. Evolution of a strategy for preparing bioactive small molecules by sequential multicomponent assembly processes, cyclizations, and diversification. Org Biomol Chem 2014; 12:7659-72. [PMID: 25135846 PMCID: PMC4167917 DOI: 10.1039/c4ob00835a] [Citation(s) in RCA: 40] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/24/2023]
Abstract
A strategy for generating diverse collections of small molecules has been developed that features a multicomponent assembly process (MCAP) to efficiently construct a variety of intermediates possessing an aryl aminomethyl subunit. These key compounds are then transformed via selective ring-forming reactions into heterocyclic scaffolds, each of which possesses suitable functional handles for further derivatizations and palladium-catalyzed cross coupling reactions. The modular nature of this approach enables the facile construction of libraries of polycyclic compounds bearing a broad range of substituents and substitution patterns for biological evaluation. Screening of several compound libraries thus produced has revealed a large subset of compounds that exhibit a broad spectrum of medicinally-relevant activities.
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Affiliation(s)
- James J Sahn
- Department of Chemistry, The University of Texas at Austin, 1 University Station A5300, Austin, TX 78712-0165, USA.
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49
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Bian Z, Marvin CC, Pettersson M, Martin SF. Enantioselective total syntheses of citrinadins A and B. Stereochemical revision of their assigned structures. J Am Chem Soc 2014; 136:14184-92. [PMID: 25211501 PMCID: PMC4195386 DOI: 10.1021/ja5074646] [Citation(s) in RCA: 56] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/22/2014] [Indexed: 11/30/2022]
Abstract
The concise, enantioselective total syntheses of (-)-citrinadin A and (+)-citrinadin B in a total of only 20 and 21 steps, respectively, from commercially available starting materials are described. Our strategy, which minimizes refunctionalization and protection/deprotection operations, features the highly diastereoselective, vinylogous Mannich addition of a dienolate to a chiral pyridinium salt to set the first chiral center. The absolute stereochemistry of this key center was then relayed by a sequence of substrate-controlled reactions, including a highly stereoselective epoxidation/ring opening sequence and an oxidative rearrangement of an indole to furnish a spirooxindole to establish the remaining stereocenters in the pentacyclic core of the citrinadins. An early stage intermediate in the synthesis of (-)-citrinadin A was deoxygenated to generate a dehydroxy compound that was elaborated into (+)-citrinadin B by a sequence of reaction identical to those used to prepare (-)-citrinadin A. These concise syntheses of (-)-citrinadin A and (+)-citrinadin B led to a revision of their stereochemical structures.
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Affiliation(s)
- Zhiguo Bian
- Department of Chemistry, The
University of Texas, Austin, Texas 78712, United States
| | | | | | - Stephen F. Martin
- Department of Chemistry, The
University of Texas, Austin, Texas 78712, United States
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50
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Abstract
A multicomponent, Mannich-type assembly process commencing with commercially available bromobenzaldehydes was sequenced with [3+2] dipolar cycloaddition reactions involving nitrones and azomethine ylides to generate collections of fused, bicyclic scaffolds based on the 2-arylpiperidine subunit. Use of the 4-pentenoyl group, which served both as an activator in the Mannich-type reaction and a readily-cleaved amine protecting group, allowed sub-libraries to be prepared through piperidine N-functionalization and cross-coupling of the aryl bromide. A number of these derivatives displayed biological activities that had not previously been associated with this substructure. Methods were also developed that allowed rapid conversion of these scaffolds to novel, polycyclic dihydroquinazolin-2-ones, 2-imino-1,3-benzothiazinanes, dihydroisoquinolin-3-ones and bridged tetrahydroquinolines.
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Affiliation(s)
- Simon Hardy
- Department of Chemistry, The University of Texas at Austin, Austin, TX 78712
| | - Stephen F. Martin
- Department of Chemistry, The University of Texas at Austin, Austin, TX 78712
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