ABSTRACT
Familial Parkinson's disease cases have recently been associated with the leucine rich repeat kinase 2 (LRRK2) gene. It has been hypothesized that inhibition of the LRRK2 protein may have the potential to alter disease pathogenesis. A dihydrobenzothiophene series of potent, selective, orally bioavailable LRRK2 inhibitors were identified from a high-throughput screen of the internal Merck sample collection. Initial SAR studies around the core established the series as a tractable small molecule lead series of LRRK2 inhibitors for potential treatment of Parkinson's disease. It was also found that incorporation of a lactam into the core drastically improved the CNS and DMPK properties of these small molecules.
Subject(s)
Leucine-Rich Repeat Serine-Threonine Protein Kinase-2/antagonists & inhibitors , Protein Kinase Inhibitors/pharmacology , Thiophenes/pharmacology , Administration, Oral , Biological Availability , Dose-Response Relationship, Drug , Humans , Leucine-Rich Repeat Serine-Threonine Protein Kinase-2/metabolism , Molecular Docking Simulation , Molecular Structure , Protein Kinase Inhibitors/administration & dosage , Protein Kinase Inhibitors/chemistry , Structure-Activity Relationship , Thiophenes/chemical synthesis , Thiophenes/chemistryABSTRACT
The EphA4 receptor and its ephrin ligands are involved in astrocytic gliosis following CNS injury. Therefore, a strategy aimed at the blockade of EphA4 signaling could have broad therapeutic interest in brain disorders. We have identified novel small molecule inhibitors of EphA4 kinase in specific enzymatic and cell-based assays. In addition, we have demonstrated in two in vitro models of scratch injury that EphA4 receptor kinase is activated through phosphorylation and is involved in the repopulation of the wound after the scratch. A potent EphA4 kinase inhibitor significantly inhibited wound closure and reduced the accumulation of the reactive astrocytes inside the scratch. We have also shown that after the transient focal cerebral ischemia in rats, a large glial scar is formed by the accumulation of astrocytes and chondroitin sulfate proteoglycan surrounding the infarcted tissue at 7 days and 14 days of reperfusion. EphA4 protein expression is highly up-regulated in the same areas at these time points, supporting its potential role in the glial scar formation and maintenance. Taken together, these results suggest that EphA4 kinase inhibitors might interfere with the astrogliosis reaction and thereby lead to improved neurological outcome after ischemic injury.
Subject(s)
Gliosis/drug therapy , Protein Kinase Inhibitors/therapeutic use , Receptor, EphA4/antagonists & inhibitors , Wounds and Injuries/pathology , Animals , Astrocytes/pathology , Blotting, Western , CHO Cells , Cell Movement/drug effects , Cells, Cultured , Cricetinae , Cricetulus , Gliosis/pathology , Humans , Immunohistochemistry , Ischemic Attack, Transient/pathology , Male , Mice , Mice, Inbred C57BL , Mice, Knockout , Microscopy, Fluorescence , Rats , Rats, Sprague-Dawley , Small Molecule Libraries , Wound Healing/drug effectsABSTRACT
This Letter describes the one pot synthesis of tertiary carbinamine 3 and related analogs of brain penetrant BACE-1 inhibitors via the alkylation of the Schiff base intermediate 2. The methodology developed for this study provided a convenient and rapid means to explore the P1 region of these types of inhibitors, where the P1 group is installed in the final step using a one-pot two-step protocol. Further SAR studies led to the identification of 10 which is twofold more potent in vitro as compared to the lead compound. This inhibitor was characterized in a cisterna magna ported rhesus monkey model, where significant lowering of CSF Abeta40 was observed.
Subject(s)
Amyloid Precursor Protein Secretases/antagonists & inhibitors , Aspartic Acid Endopeptidases/antagonists & inhibitors , Brain/enzymology , Enzyme Inhibitors/chemistry , Oxadiazoles/chemistry , Sulfonamides/chemistry , Amyloid Precursor Protein Secretases/metabolism , Amyloid beta-Peptides/metabolism , Animals , Aspartic Acid Endopeptidases/metabolism , Brain/metabolism , Enzyme Inhibitors/chemical synthesis , Enzyme Inhibitors/pharmacokinetics , Humans , Macaca mulatta , Oxadiazoles/chemical synthesis , Oxadiazoles/pharmacokinetics , Peptide Fragments/metabolism , Structure-Activity Relationship , Sulfonamides/chemical synthesis , Sulfonamides/pharmacokineticsABSTRACT
The optimization of tertiary carbinamine derived inhibitors of BACE1 from its discovery as an unstable lead to low nanomolar cell active compounds is described. Five-membered heterocycles are reported as stable and potency enhancing linkers. In the course of this work, we have discovered a clear trend where the activity of inhibitors at a given assay pH is dependent on pK(a) of the amino group that interacts directly with the catalytic aspartates. The potency of compounds as inhibitors of Alphabeta production in a cell culture assay correlated much better with BACE1 enzyme potency measured at pH 7.5 than at pH 4.5.
Subject(s)
Amines/metabolism , Amyloid Precursor Protein Secretases/antagonists & inhibitors , Aspartic Acid Endopeptidases/antagonists & inhibitors , Aspartic Acid/metabolism , Enzyme Inhibitors/pharmacology , Catalysis , Humans , Models, Molecular , Structure-Activity RelationshipSubject(s)
Amines/chemistry , Amyloid Precursor Protein Secretases/antagonists & inhibitors , Amyloid beta-Peptides/cerebrospinal fluid , Peptide Fragments/cerebrospinal fluid , Protease Inhibitors/chemistry , Administration, Oral , Amines/administration & dosage , Amines/pharmacology , Amyloid Precursor Protein Secretases/chemistry , Amyloid Precursor Protein Secretases/metabolism , Animals , Blood-Brain Barrier , Crystallography, X-Ray , Haplorhini , Inhibitory Concentration 50 , Macaca mulatta , Molecular Conformation , Protease Inhibitors/administration & dosage , Protease Inhibitors/pharmacology , Structure-Activity RelationshipABSTRACT
This letter describes replacements for the P3 amide moiety present in previously reported tertiary carbinamine macrolactones. Although P-gp efflux issues associated with these amide-macrolactones were solved and full brain penetration was measured in one case, potency was compromised in the process.
Subject(s)
Amines/pharmacokinetics , Amyloid Precursor Protein Secretases/antagonists & inhibitors , Aspartic Acid Endopeptidases/antagonists & inhibitors , Brain/metabolism , Enzyme Inhibitors/pharmacokinetics , Crystallography, X-Ray , Models, MolecularABSTRACT
The X-linked inhibitor of apoptosis proteins (XIAP) is thought to play a key role in the unchecked proliferation of cancer cells by interfering with the signaling cascade leading to cell death. The structure and mechanism of XIAP has been widely investigated and characterized over the past few years, to the point where this may be the best understood apoptosis protein inhibitor. As a result, XIAP is viewed as an attractive target for the treatment of cancer. To date, several research groups have reported on the discovery of small molecule inhibitors of this protein. This review focuses on the discovery and optimization of these leads.
Subject(s)
Antineoplastic Agents , Caspases , X-Linked Inhibitor of Apoptosis Protein , Animals , Antineoplastic Agents/chemistry , Antineoplastic Agents/pharmacology , Caspase Inhibitors , Caspases/chemistry , Caspases/genetics , Drug Design , Humans , Molecular Mimicry , Molecular Structure , Protein Binding , Protein Interaction Mapping , X-Linked Inhibitor of Apoptosis Protein/antagonists & inhibitors , X-Linked Inhibitor of Apoptosis Protein/chemistry , X-Linked Inhibitor of Apoptosis Protein/geneticsABSTRACT
This Letter describes the design and synthesis of tertiary carbinamine macrocyclic inhibitors of the beta-secretase (BACE-1) enzyme. These macrocyclic inhibitors, some of which incorporate novel P2 substituents, display a 2- to 100-fold increase in potency relative to the previously described acyclic analogs while affording greater stability.
Subject(s)
Amines/chemistry , Amines/pharmacology , Amyloid Precursor Protein Secretases/antagonists & inhibitors , Aspartic Acid Endopeptidases/antagonists & inhibitors , Protease Inhibitors/chemistry , Protease Inhibitors/pharmacology , Amines/chemical synthesis , Cyclization , Drug Design , Models, Molecular , Protease Inhibitors/chemical synthesis , Structure-Activity RelationshipABSTRACT
BACE-1 is a flexible enzyme with experimentally determined motion in the flap region, the catalytic aspartates, and the 10s loop. Four in-house crystallographically determined complexes of tertiary carbinamine inhibitors revealed 10s loop motion in the S(3) pocket. These X-ray structures were used to correlate K(i) values, which span over five orders of magnitude, with the calculated interaction energy, using the Merck Molecular Force Field for a series of 19 tertiary carbinamine inhibitors.
Subject(s)
Amyloid Precursor Protein Secretases/antagonists & inhibitors , Enzyme Inhibitors/pharmacology , Aspartic Acid/analogs & derivatives , Aspartic Acid/chemistry , Aspartic Acid/pharmacology , Binding Sites , Catalysis , Chemical Phenomena , Chemistry, Physical , Crystallography, X-Ray , Enzyme Inhibitors/chemistry , Ligands , Molecular Conformation , Structure-Activity Relationship , ThermodynamicsABSTRACT
We describe the discovery and optimization of tertiary carbinamine derived inhibitors of the enzyme beta-secretase (BACE-1). These novel non-transition-state-derived ligands incorporate a single primary amine to interact with the catalytic aspartates of the target enzyme. Optimization of this series provided inhibitors with intrinsic and functional potency comparable to evolved transition state isostere derived inhibitors of BACE-1.
Subject(s)
Amyloid Precursor Protein Secretases/antagonists & inhibitors , Amyloid Precursor Protein Secretases/chemistry , Aniline Compounds/chemical synthesis , Oxadiazoles/chemical synthesis , Aniline Compounds/chemistry , Crystallography, X-Ray , Models, Molecular , Oxadiazoles/chemistryABSTRACT
We describe the development of cell-permeable beta-secretase inhibitors that demonstratively inhibit the production of the secreted amino terminal fragment of an artificial amyloid precursor protein in cell culture. In addition to potent inhibition in a cell-based assay (IC50 < 100 nM), these inhibitors display impressive selectivity against other biologically relevant aspartyl proteases.
