ABSTRACT
An experimental approach is described for late-stage lead diversification of frontrunner drug candidates using nanomole-scale amounts of lead compounds for structure-activity relationship development. The process utilizes C-H bond activation methods to explore chemical space by transforming candidates into newly functionalized leads. A key to success is the utilization of microcryoprobe nuclear magnetic resonance (NMR) spectroscopy, which permits the use of low amounts of lead compounds (1-5 µmol). The approach delivers multiple analogues from a single lead at nanomole-scale amounts as DMSO-d6 stock solutions with a known structure and concentration for in vitro pharmacology and absorption, distribution, metabolism, and excretion testing. To demonstrate the feasibility of this approach, we have used the antihistamine agent loratadine (1). Twenty-six analogues of loratadine were isolated and fully characterized by NMR. Informative SAR analogues were identified, which display potent affinity for the human histamine H1 receptor and improved metabolic stability.
Subject(s)
Loratadine/analogs & derivatives , Loratadine/pharmacokinetics , Structure-Activity Relationship , Animals , Chromatography, High Pressure Liquid , Cytochrome P-450 Enzyme System/genetics , Cytochrome P-450 Enzyme System/metabolism , Dimethyl Sulfoxide/chemistry , Dogs , Drug Discovery/methods , Histamine H1 Antagonists, Non-Sedating/chemistry , Histamine H1 Antagonists, Non-Sedating/pharmacology , Humans , Hydrogen Bonding , Inactivation, Metabolic , Loratadine/chemistry , Magnetic Resonance Spectroscopy , Metalloporphyrins/chemistry , Metalloporphyrins/metabolism , Microsomes, Liver/drug effects , Microsomes, Liver/metabolism , Rabbits , Recombinant Proteins/genetics , Recombinant Proteins/metabolism , Tandem Mass Spectrometry , Tissue DistributionABSTRACT
This work describes two distinct routes to prepare pyrazolo[1,5-alpha]pyrimidin-7-ones and two distinct routes to prepare pyrazolo[1,5-alpha]pyrimidin-5-ones. Use of 1,3-dimethyluracil as the electrophile in the preparation of the pyrimidin-5-one regioisomer represents a correction of previously reported results. Also, a novel reaction to prepare this isomer was identified and the reaction mechanism elucidated. This work provides the experimentalist with complimentary synthetic pathways that afford either the pyrimidin-7-one or the pyrimidin-5-one regioisomer.
Subject(s)
Anti-Inflammatory Agents/chemical synthesis , Pyrazoles/chemistry , Pyrimidinones/chemistry , Isomerism , Models, Chemical , Schistosomicides/chemical synthesis , Uracil/analogs & derivatives , Uracil/chemistryABSTRACT
Through high throughput screening, substituted proline sulfonamide 6 was identified as HCV NS5b RNA-dependent RNA polymerase inhibitor. Optimization of various regions of the lead molecule resulted in compounds that displayed good potency and selectivity. The crystal structure of 6 and NS5b polymerase complex confirmed the binding near the active site region. The optimization approach and SAR are discussed in detail.
Subject(s)
Antiviral Agents/chemical synthesis , Proline/analogs & derivatives , Proline/chemical synthesis , Sulfonamides/chemical synthesis , Viral Nonstructural Proteins/antagonists & inhibitors , Viral Nonstructural Proteins/chemistry , Antiviral Agents/chemistry , Binding Sites , Crystallography, X-Ray , Models, Molecular , Molecular Conformation , Proline/chemistry , Structure-Activity Relationship , Sulfonamides/chemistryABSTRACT
A novel class of HCV NS5B RNA dependent RNA polymerase inhibitors containing 2,3,4,9-tetrahydro-1H-carbazole and 1,2,3,4-tetrahydro-cyclopenta[b]indole scaffolds were designed and synthesized. Optimization of the aromatic region showed preference for 5,8-disubstitution pattern in both the scaffolds examined while favoring the n-propyl moiety for the C-1 position. 1,2,3,4-tetrahydro-cyclopenta[b]indole scaffold was slightly more potent than the corresponding 2,3,4,9-tetrahydro-1H-carbazole and analogue 36 displayed an IC50 of 550 nM against HCV NS5B enzyme.
Subject(s)
Antiviral Agents/chemical synthesis , Carbazoles , Cyclopentanes , Indoles , RNA-Dependent RNA Polymerase/antagonists & inhibitors , Reverse Transcriptase Inhibitors/chemical synthesis , Viral Nonstructural Proteins/drug effects , Antiviral Agents/chemistry , Antiviral Agents/pharmacology , Carbazoles/chemical synthesis , Carbazoles/chemistry , Carbazoles/pharmacology , Cyclopentanes/chemical synthesis , Cyclopentanes/chemistry , Cyclopentanes/pharmacology , Drug Design , Indoles/chemical synthesis , Indoles/chemistry , Indoles/pharmacology , Microbial Sensitivity Tests , Molecular Structure , Reverse Transcriptase Inhibitors/chemistry , Reverse Transcriptase Inhibitors/pharmacology , Structure-Activity RelationshipABSTRACT
A novel class of HCV NS5B RNA dependent RNA polymerase inhibitors containing 3,4-dihydro-1H-[1]-benzothieno[2,3-c]pyran and 3,4-dihydro-1H-pyrano[3,4-b]benzofuran scaffolds were designed and synthesized. Optimization of the alkyl substituent in the pyran ring showed preference for an n-propyl group, while 5,8-disubstitution pattern is preferred for the aromatic region. Analog 19 displayed potent activity with an IC(50) of 50 nM against HCV NS5B enzyme and was selective over a panel of polymerases.
Subject(s)
Benzofurans , Enzyme Inhibitors/chemical synthesis , Enzyme Inhibitors/pharmacology , Pyrans , RNA-Dependent RNA Polymerase/antagonists & inhibitors , Viral Nonstructural Proteins/antagonists & inhibitors , Animals , Benzofurans/chemical synthesis , Benzofurans/chemistry , Benzofurans/pharmacology , Cell Line, Tumor , Chlorocebus aethiops , Drug Design , Drug Evaluation, Preclinical , Enzyme Inhibitors/chemistry , Humans , Molecular Structure , Pyrans/chemical synthesis , Pyrans/chemistry , Pyrans/pharmacology , RNA-Dependent RNA Polymerase/chemistry , Structure-Activity Relationship , Vero Cells , Viral Nonstructural Proteins/chemistryABSTRACT
A novel series of HCV NS5B RNA-dependent RNA polymerase inhibitors containing a pyrano[3,4-b]indole scaffold is described leading to the discovery of compound 16, a highly potent and selective inhibitor that is active in the replicon system.
