ABSTRACT
This paper describes the structure-activity-relationships of novel fluoroalkyl substituents at the C2 position of iminothiazine dioxide beta secretase inhibitors. Key discoveries include reduced amidine basicity and its effect on Pgp, cell potency, and efficacy in various preclinical in vivo efficacy animal models. Findings from these structure-activity-relationships are discussed.
Subject(s)
Amyloid Precursor Protein Secretases/antagonists & inhibitors , Aspartic Acid Endopeptidases/antagonists & inhibitors , Drug Discovery , Enzyme Inhibitors/pharmacology , Oxides/pharmacology , Thiazines/pharmacology , Administration, Oral , Amyloid Precursor Protein Secretases/metabolism , Animals , Aspartic Acid Endopeptidases/metabolism , Dose-Response Relationship, Drug , Enzyme Inhibitors/administration & dosage , Enzyme Inhibitors/chemistry , HEK293 Cells , Humans , Molecular Structure , Oxides/administration & dosage , Oxides/chemistry , Rats , Structure-Activity Relationship , Thiazines/administration & dosage , Thiazines/chemistryABSTRACT
Functional magnetic resonance imaging (fMRI) is a valuable tool for studying neural activations in the central nervous system of animals due to its wide spatial coverage and non-invasive nature. However, the advantages of fMRI have not been fully realized in functional studies in mice, especially in the olfactory system, possibly due to the lack of suitable anesthesia protocols with spontaneous breathing. Since mice are widely used in biomedical research, it is desirable to evaluate different anesthesia protocols for olfactory fMRI studies in mice. Dexmedetomidine (DEX) as a sedative/anesthetic has been introduced to fMRI studies in mice, but it has a limited anesthesia duration. To extend the anesthesia duration, DEX has been combined with a low dose of isoflurane (ISO) or ketamine (KET) in previous functional studies in mice. In this report, olfactory fMRI studies were performed under three anesthesia protocols (DEX alone, DEX/ISO, and DEX/KET) in three different groups of mice. Isoamyl-acetate was used as an odorant, and the odorant-induced neural activations were measured by blood oxygenation-level dependent (BOLD) fMRI. BOLD fMRI responses were observed in the olfactory bulb (OB), anterior olfactory nuclei (AON), and piriform cortex (Pir). Interestingly, BOLD fMRI activations were also observed in the prefrontal cortical region (PFC), which are most likely caused by the draining vein effect. The response in the OB showed no adaptation to either repeated odor stimulations or continuous odor exposure, but the response in the Pir showed adaptation during the continuous odor exposure. The data also shows that ISO suppresses the olfactory response in the OB and AON, while KET enhances the olfactory response in the Pir. Thus, DEX/KET should be an attractive anesthesia for olfactory fMRI in mice.
Subject(s)
Dexmedetomidine/pharmacology , Isoflurane/pharmacology , Ketamine/pharmacology , Olfactory Bulb/drug effects , Olfactory Perception/drug effects , Anesthetics/pharmacology , Animals , Hypnotics and Sedatives/pharmacology , Magnetic Resonance Imaging/methods , Mice , Models, AnimalABSTRACT
Deposition of hyperphosphorylated and aggregated tau protein in the central nervous system is characteristic of Alzheimer disease and other tauopathies. Tau is subject to O-linked N-acetylglucosamine (O-GlcNAc) modification, and O-GlcNAcylation of tau has been shown to influence tau phosphorylation and aggregation. Inhibition of O-GlcNAcase (OGA), the enzyme that removes O-GlcNAc moieties, is a novel strategy to attenuate the formation of pathologic tau. Here we described the in vitro and in vivo pharmacological properties of a novel and selective OGA inhibitor, MK-8719. In vitro, this compound is a potent inhibitor of the human OGA enzyme with comparable activity against the corresponding enzymes from mouse, rat, and dog. In vivo, oral administration of MK-8719 elevates brain and peripheral blood mononuclear cell O-GlcNAc levels in a dose-dependent manner. In addition, positron emission tomography imaging studies demonstrate robust target engagement of MK-8719 in the brains of rats and rTg4510 mice. In the rTg4510 mouse model of human tauopathy, MK-8719 significantly increases brain O-GlcNAc levels and reduces pathologic tau. The reduction in tau pathology in rTg4510 mice is accompanied by attenuation of brain atrophy, including reduction of forebrain volume loss as revealed by volumetric magnetic resonance imaging analysis. These findings suggest that OGA inhibition may reduce tau pathology in tauopathies. However, since hundreds of O-GlcNAcylated proteins may be influenced by OGA inhibition, it will be critical to understand the physiologic and toxicological consequences of chronic O-GlcNAc elevation in vivo. SIGNIFICANCE STATEMENT: MK-8719 is a novel, selective, and potent O-linked N-acetylglucosamine (O-GlcNAc)-ase (OGA) inhibitor that inhibits OGA enzyme activity across multiple species with comparable in vitro potency. In vivo, MK-8719 elevates brain O-GlcNAc levels, reduces pathological tau, and ameliorates brain atrophy in the rTg4510 mouse model of tauopathy. These findings indicate that OGA inhibition may be a promising therapeutic strategy for the treatment of Alzheimer disease and other tauopathies.
Subject(s)
Enzyme Inhibitors/pharmacology , Tauopathies/drug therapy , Tauopathies/metabolism , beta-N-Acetylhexosaminidases/antagonists & inhibitors , tau Proteins/metabolism , Animals , Atrophy/drug therapy , Brain/drug effects , Brain/metabolism , Brain/pathology , Disease Models, Animal , Enzyme Inhibitors/therapeutic use , Locomotion/drug effects , Male , Mice , PC12 Cells , Rats , Tauopathies/pathology , Tauopathies/physiopathologyABSTRACT
In this paper we describe our strategy to improve the aqueous solubility of SCH 900229, a potent PS1-selective γ-secretase inhibitor for the treatment of Alzheimer's disease. Incorporation of ionizable amino groups into the side chain terminal generates water soluble ß-aminosulfone analogues of SCH 900229 that maintain robust in vitro potency and in vivo efficacy.
Subject(s)
Alzheimer Disease/drug therapy , Amyloid Precursor Protein Secretases/antagonists & inhibitors , Benzopyrans/chemistry , Benzopyrans/pharmacology , Enzyme Inhibitors/chemistry , Enzyme Inhibitors/pharmacology , Sulfones/chemistry , Sulfones/pharmacology , Alzheimer Disease/enzymology , Amyloid Precursor Protein Secretases/metabolism , Animals , Benzopyrans/pharmacokinetics , Dogs , Drug Design , Enzyme Inhibitors/pharmacokinetics , Haplorhini , Humans , Rats , Solubility , Sulfones/pharmacokinetics , Water/chemistryABSTRACT
Mutations in the leucine-rich repeat kinase 2 (LRRK2) gene are the most common genetic cause of familial and sporadic Parkinson's disease (PD). That the most prevalent mutation, G2019S, leads to increased kinase activity has led to a concerted effort to identify LRRK2 kinase inhibitors as a potential disease-modifying therapy for PD. An internal medicinal chemistry effort identified several potent and highly selective compounds with favorable drug-like properties. Here, we characterize the pharmacological properties of cis-2,6-dimethyl-4-(6-(5-(1-methylcyclopropoxy)-1H-indazol-3-yl)pyrimidin-4-yl)morpholine (MLi-2), a structurally novel, highly potent, and selective LRRK2 kinase inhibitor with central nervous system activity. MLi-2 exhibits exceptional potency in a purified LRRK2 kinase assay in vitro (IC50 = 0.76 nM), a cellular assay monitoring dephosphorylation of LRRK2 pSer935 LRRK2 (IC50 = 1.4 nM), and a radioligand competition binding assay (IC50 = 3.4 nM). MLi-2 has greater than 295-fold selectivity for over 300 kinases in addition to a diverse panel of receptors and ion channels. Acute oral and subchronic dosing in MLi-2 mice resulted in dose-dependent central and peripheral target inhibition over a 24-hour period as measured by dephosphorylation of pSer935 LRRK2. Treatment of MitoPark mice with MLi-2 was well tolerated over a 15-week period at brain and plasma exposures >100× the in vivo plasma IC50 for LRRK2 kinase inhibition as measured by pSer935 dephosphorylation. Morphologic changes in the lung, consistent with enlarged type II pneumocytes, were observed in MLi-2-treated MitoPark mice. These data demonstrate the suitability of MLi-2 as a compound to explore LRRK2 biology in cellular and animal models.
Subject(s)
Antiparkinson Agents/adverse effects , Antiparkinson Agents/therapeutic use , Indazoles/pharmacology , Protein Kinase Inhibitors/adverse effects , Protein Kinase Inhibitors/therapeutic use , Protein Serine-Threonine Kinases/antagonists & inhibitors , Pyrimidines/pharmacology , Alveolar Epithelial Cells/drug effects , Alveolar Epithelial Cells/pathology , Animals , Behavior, Animal/drug effects , Binding, Competitive , Brain/metabolism , Brain Chemistry/drug effects , Cell Line , Cerebral Cortex/drug effects , Cerebral Cortex/metabolism , Dose-Response Relationship, Drug , Humans , Leucine-Rich Repeat Serine-Threonine Protein Kinase-2 , Lung/pathology , Male , Mice , Mice, Inbred C57BL , Mutation/genetics , Parkinson Disease/drug therapy , Parkinson Disease/pathology , Parkinson Disease/psychology , Phosphorylation , Protein Serine-Threonine Kinases/genetics , Protein Serine-Threonine Kinases/metabolismABSTRACT
In an attempt to further improve overall profiles of the oxadiazine series of GSMs, in particular the hERG activity, conformational modifications of the core structure resulted in the identification of fused oxadiazepines such as 7i which had an improved hERG inhibition profile and was a highly efficacious GSM in vitro and in vivo in rats. These SAR explorations offer opportunities to identify potential drugs to treat Alzheimer's disease.
Subject(s)
Alzheimer Disease/drug therapy , Amyloid Precursor Protein Secretases/metabolism , Azepines/chemical synthesis , Drug Discovery , Ether-A-Go-Go Potassium Channels/antagonists & inhibitors , Animals , Azepines/chemistry , Azepines/pharmacology , ERG1 Potassium Channel , Enzyme Activation/drug effects , Enzyme Inhibitors/chemistry , Enzyme Inhibitors/pharmacology , Humans , Inhibitory Concentration 50 , Molecular Structure , Rats , Structure-Activity RelationshipABSTRACT
An investigation is detailed of the structure activity relationships (SAR) of two sulfone side chains of compound (-)-1a (SCH 900229), a potent, PS1-selective γ-secretase inhibitor and clinical candidate for the treatment of Alzheimer's disease. Specifically, 4-CF(3) and 4-Br substituted arylsulfone analogs, (-)-1b and (-)-1c, are equipotent to compound (-)-1a. On the right hand side chain, linker size and terminal substituents of the pendant sulfone group are also investigated.
Subject(s)
Amyloid Precursor Protein Secretases/antagonists & inhibitors , Benzopyrans/chemical synthesis , Benzopyrans/pharmacology , Enzyme Inhibitors/chemistry , Enzyme Inhibitors/pharmacology , Sulfones/chemical synthesis , Sulfones/pharmacology , Benzopyrans/chemistry , Cyclization , Enzyme Activation/drug effects , Humans , Inhibitory Concentration 50 , Molecular Structure , Pyrans/chemical synthesis , Pyrans/chemistry , Pyrans/pharmacology , Structure-Activity Relationship , Sulfones/chemistryABSTRACT
From an initial lead 1, a structure-based design approach led to identification of a novel, high-affinity iminohydantoin BACE1 inhibitor that lowers CNS-derived Aß following oral administration to rats. Herein we report SAR development in the S3 and F' subsites of BACE1 for this series, the synthetic approaches employed in this effort, and in vivo data for the optimized compound.
Subject(s)
Alzheimer Disease/drug therapy , Amyloid Precursor Protein Secretases/antagonists & inhibitors , Amyloid beta-Peptides/antagonists & inhibitors , Anticonvulsants/chemical synthesis , Aspartic Acid Endopeptidases/antagonists & inhibitors , Enzyme Inhibitors/chemical synthesis , Hydantoins/chemical synthesis , Administration, Oral , Alzheimer Disease/blood , Alzheimer Disease/cerebrospinal fluid , Amyloid Precursor Protein Secretases/metabolism , Amyloid beta-Peptides/blood , Amyloid beta-Peptides/cerebrospinal fluid , Animals , Anticonvulsants/pharmacology , Aspartic Acid Endopeptidases/metabolism , Binding Sites , Computer Simulation , Crystallography, X-Ray , Disease Models, Animal , Drug Design , Enzyme Inhibitors/pharmacology , Humans , Hydantoins/pharmacology , Models, Molecular , Protein Binding , Rats , Rats, Sprague-DawleyABSTRACT
SAR exploration at C-6 and C-8 positions of the tricyclic sulfone series was carried out. Several functional groups were found to be well tolerated at C-6 and C-8 positions. Selective combination of C-6 and C-8 modification resulted in new tricyclic sulfone analogs with efficacy in in vivo mouse Aß(40) lowering model.
Subject(s)
Amyloid Precursor Protein Secretases/antagonists & inhibitors , Enzyme Inhibitors/chemical synthesis , Enzyme Inhibitors/pharmacology , Sulfones/chemical synthesis , Sulfones/pharmacology , Amyloid beta-Peptides/metabolism , Animals , Cyclization , Disease Models, Animal , Enzyme Activation/drug effects , Enzyme Inhibitors/chemistry , Inhibitory Concentration 50 , Mice , Molecular Structure , Peptide Fragments/metabolism , Structure-Activity Relationship , Sulfones/chemistryABSTRACT
We herein report the discovery of four series of fused 5,6-bicyclic heterocycles as γ-secretase modulators. Synthesis and SAR of these series are discussed. These compounds represent a new class of γ-secretase modulators that demonstrate moderate to good in vitro potency in inhibiting Aß(42) production.
Subject(s)
Amyloid Precursor Protein Secretases/metabolism , Amyloid beta-Peptides/antagonists & inhibitors , Bridged Bicyclo Compounds, Heterocyclic/chemistry , Bridged Bicyclo Compounds, Heterocyclic/pharmacology , Alzheimer Disease/drug therapy , Amyloid beta-Peptides/metabolism , Animals , Bridged Bicyclo Compounds, Heterocyclic/pharmacokinetics , Humans , Rats , Structure-Activity RelationshipABSTRACT
Tricyclic sulfones were designed as gamma-secretase inhibitors and found to have excellent potency. Extensive SAR shows that a large number of sulfonamides at position 7 of the tricycle are very well tolerated. Compounds such as 15a and 15c showed remarkable in vivo potency.
Subject(s)
Amyloid Precursor Protein Secretases/antagonists & inhibitors , Sulfones/chemistry , Sulfones/pharmacology , Administration, Oral , Amyloid beta-Peptides/antagonists & inhibitors , Amyloid beta-Peptides/blood , Animals , Brain Chemistry/drug effects , Mice , Protease Inhibitors/chemical synthesis , Protease Inhibitors/chemistry , Structure-Activity Relationship , Sulfonamides/chemical synthesis , Sulfonamides/chemistry , Sulfonamides/pharmacology , Sulfones/chemical synthesisABSTRACT
Complex tetracyclic sulfones were designed as gamma-secretase inhibitors and a stereoselective synthesis was achieved. Gamma-secretase activity was seen predominately in the (-) enantiomeric series. Compounds such as 2a and 2b showed remarkable in vitro and in vivo potency.
Subject(s)
Amyloid Precursor Protein Secretases/antagonists & inhibitors , Protease Inhibitors/chemical synthesis , Sulfones/chemistry , Amyloid beta-Peptides/antagonists & inhibitors , Animals , Drug Design , Hepatocytes/metabolism , Humans , Mice , Stereoisomerism , Structure-Activity Relationship , Sulfones/chemical synthesis , Sulfones/pharmacologyABSTRACT
The synthesis of a novel series of iminoheterocycles and their structure-activity relationship (SAR) as modulators of gamma-secretase activity will be detailed. Encouraging SAR generated from a monocyclic core led to a structurally unique bicyclic core. Selected compounds exhibit good potency as gamma-secretase modulators, excellent rat pharmacokinetics, and lowering of Abeta42 levels in various in vivo models.
Subject(s)
Alzheimer Disease/drug therapy , Amyloid Precursor Protein Secretases/metabolism , Amyloid beta-Peptides/metabolism , Imines/chemistry , Imines/therapeutic use , Peptide Fragments/metabolism , Amyloid beta-Peptides/antagonists & inhibitors , Animals , Brain/metabolism , Bridged Bicyclo Compounds, Heterocyclic/chemistry , Bridged Bicyclo Compounds, Heterocyclic/pharmacokinetics , Bridged Bicyclo Compounds, Heterocyclic/therapeutic use , Humans , Imines/pharmacokinetics , Mice , Mice, Transgenic , Peptide Fragments/antagonists & inhibitors , Rats , Structure-Activity RelationshipABSTRACT
A novel series of tricyclic gamma-secretase inhibitors was designed and synthesized via a conformational analysis of literature compounds. The preliminary results have shown that compounds in this new series have much improved in vitro potency and in vivo profiles. More importantly, they have greatly reduced Notch related toxicity that was associated with previous gamma-secretase inhibitors.
Subject(s)
Amyloid Precursor Protein Secretases/antagonists & inhibitors , Receptors, Notch/drug effects , Sulfones/chemistry , Sulfones/pharmacology , Animals , Crystallography, X-Ray , Drug Design , Mice , Models, Molecular , Sulfones/chemical synthesisABSTRACT
While the peripheral nervous system is able to repair itself following injury and disease, recovery is often slow and incomplete, with no available treatments to enhance the effectiveness of regeneration. Using knock-out and transgenic overexpressor mice, we previously reported that BACE1, an aspartyl protease, as reported by Hemming et al. (PLoS One 4:12, 2009), negatively regulates peripheral nerve regeneration. Here, we investigated whether pharmacological inhibition of BACE may enhance peripheral nerve repair following traumatic nerve injury or neurodegenerative disease. BACE inhibitor-treated mice had increased numbers of regenerating axons and enhanced functional recovery after a sciatic nerve crush while inhibition increased axonal sprouting following a partial nerve injury. In the SOD1G93A ALS mouse model, BACE inhibition increased axonal regeneration with improved muscle re-innervation. CHL1, a BACE1 substrate, was elevated in treated mice and may mediate enhanced regeneration. Our data demonstrates that pharmacological BACE inhibition accelerates peripheral axon regeneration after varied nerve injuries and could be used as a potential therapy.
Subject(s)
Amyloid Precursor Protein Secretases/antagonists & inhibitors , Amyloid Precursor Protein Secretases/metabolism , Amyotrophic Lateral Sclerosis/enzymology , Aspartic Acid Endopeptidases/antagonists & inhibitors , Aspartic Acid Endopeptidases/metabolism , Axons/physiology , Nerve Regeneration/physiology , Peripheral Nerve Injuries/enzymology , Amyotrophic Lateral Sclerosis/drug therapy , Amyotrophic Lateral Sclerosis/genetics , Animals , Axons/drug effects , Cells, Cultured , Disease Models, Animal , Enzyme Inhibitors/pharmacology , Enzyme Inhibitors/therapeutic use , Female , HEK293 Cells , Humans , Male , Mice , Mice, Inbred C57BL , Mice, Knockout , Mice, Transgenic , Nerve Regeneration/drug effects , Peripheral Nerve Injuries/drug therapy , Peripheral Nerve Injuries/genetics , Superoxide Dismutase/geneticsABSTRACT
Herein, we disclose three structurally differentiated γ-secretase modulators (GSMs) based on an oxadiazine scaffold. The analogues from series I potently inhibit the generation of Aß42 in vitro when the substituents at 3 and 4 positions of the oxadiazine moiety adopt an α orientation (cf. 11). To address the concern around potential reactivity of the exocyclic double bond present in series I toward nucleophilic attack, compounds containing either an endocyclic double bond, such as 20 (series II), or devoid of an olefinic moiety, such as 27 (series III), were designed and validated as novel GSMs. Compound 11 and azepine 20 exhibit robust lowering of CSF Aß42 in rats treated with a 30 mg/kg oral dose.
Subject(s)
Amyloid Precursor Protein Secretases/antagonists & inhibitors , Amyloid Precursor Protein Secretases/metabolism , Alkenes/chemistry , Alkenes/pharmacology , Amyloid beta-Peptides/antagonists & inhibitors , Amyloid beta-Peptides/cerebrospinal fluid , Animals , Binding Sites/physiology , HEK293 Cells , Humans , Oxadiazoles/chemistry , Oxadiazoles/pharmacology , Peptide Fragments/antagonists & inhibitors , Peptide Fragments/cerebrospinal fluid , Rats , Structure-Activity RelationshipABSTRACT
A new class of 2,6-disubstituted morpholine N-arylsulfonamide gamma-secretase inhibitors was designed based on the introduction of a morpholine core in lieu or piperidine in our lead series. This resulted in compounds with improved CYP 3A4 profiles. Several analogs that were active at lowering Abeta levels in Tg CRND8 mice upon oral administration were identified.
Subject(s)
Amyloid Precursor Protein Secretases/antagonists & inhibitors , Cytochrome P-450 CYP3A Inhibitors , Enzyme Inhibitors/chemistry , Morpholines/chemistry , Sulfonamides/chemistry , Administration, Oral , Amyloid Precursor Protein Secretases/metabolism , Animals , Cytochrome P-450 CYP3A/metabolism , Disease Models, Animal , Enzyme Inhibitors/chemical synthesis , Enzyme Inhibitors/pharmacokinetics , Humans , Mice , Mice, Transgenic , Morpholines/chemical synthesis , Morpholines/pharmacokinetics , Rats , Sulfonamides/chemical synthesis , Sulfonamides/pharmacokineticsABSTRACT
The design of amide and heteroaryl amide isosteres as replacements for the carbamate substructure in previously disclosed 2,6-disubstituted piperidine N-arylsulfonamides is described. In several cases, amides lessened CYP liabilities in this class of gamma-secretase inhibitors. Selected compounds showed significant reduction of Abeta levels upon oral dosing in a transgenic murine model of Alzheimer's disease.
Subject(s)
Amides/chemistry , Amides/pharmacology , Amyloid Precursor Protein Secretases/antagonists & inhibitors , Heterocyclic Compounds/chemistry , Heterocyclic Compounds/pharmacology , Protease Inhibitors/chemistry , Protease Inhibitors/pharmacology , Amides/pharmacokinetics , Amyloid beta-Peptides/metabolism , Animals , Carbamates/chemistry , Carbamates/pharmacokinetics , Carbamates/pharmacology , Cytochrome P-450 Enzyme Inhibitors , Heterocyclic Compounds/pharmacokinetics , Mice , Oxadiazoles/chemistry , Oxadiazoles/pharmacokinetics , Oxadiazoles/pharmacology , Piperidines/chemistry , Piperidines/pharmacokinetics , Piperidines/pharmacology , Protease Inhibitors/pharmacokinetics , Rats , Structure-Activity RelationshipABSTRACT
Herein we describe structure-activity relationship (SAR) and metabolite identification (Met-ID) studies that provided insight into the origin of time-dependent inhibition (TDI) of cytochrome P450 3A4 (CYP3A4) by compound 1. Collectively, these efforts revealed that bioactivation of the fluoropyrimidine moiety of 1 led to reactive metabolite formation via oxidative defluorination and was responsible for the observed TDI. We discovered that substitution at both the 4- and 6-positions of the 5-fluoropyrimidine of 1 was necessary to ameliorate this TDI as exemplified by compound 19.
Subject(s)
Cytochrome P-450 CYP3A Inhibitors/chemistry , Cytochrome P-450 CYP3A Inhibitors/pharmacology , Cytochrome P-450 CYP3A/metabolism , Pyrimidines/chemistry , Pyrimidines/pharmacology , Animals , Cytochrome P-450 CYP3A Inhibitors/pharmacokinetics , Humans , Kinetics , Pyrimidines/pharmacokinetics , Rats , Structure-Activity Relationship , Tissue DistributionABSTRACT
The design and synthesis of a new series of tetrahydrobenzisoxazoles as modulators of γ-secretase activity and their structure-activity relationship (SAR) will be detailed. Several compounds are active γ-secretase modulators (GSMs) with good to excellent selectivity for the reduction of Aß42 in the cellular assay. Compound 14a was tested in vivo in a nontransgenic rat model and was found to significantly reduce Aß42 in the CNS compartment compared to vehicle-treated animals (up to 58% reduction of cerebrospinal fluid Aß42 as measured 3 h after an acute oral dosing at 30 mg/kg).