ABSTRACT
Infections caused by hepatitis C virus (HCV) are a significant world health problem for which novel therapies are in urgent demand. The polymerase of HCV is responsible for the replication of viral genome and has been a prime target for drug discovery efforts. Here, we report on the further development of tetracyclic indole inhibitors, binding to an allosteric site on the thumb domain. Structure-activity relationship (SAR) studies around an indolo-benzoxazocine scaffold led to the identification of compound 33 (MK-3281), an inhibitor with good potency in the HCV subgenomic replication assay and attractive molecular properties suitable for a clinical candidate. The compound caused a consistent decrease in viremia in vivo using the chimeric mouse model of HCV infection.
Subject(s)
Antiviral Agents/chemical synthesis , Hepacivirus/drug effects , Indoles/chemical synthesis , Oxazocines/chemical synthesis , RNA-Dependent RNA Polymerase/antagonists & inhibitors , Viral Nonstructural Proteins/antagonists & inhibitors , Administration, Oral , Animals , Antiviral Agents/pharmacokinetics , Antiviral Agents/pharmacology , Biological Availability , Cell Line, Tumor , Crystallography, X-Ray , Dogs , Hepacivirus/enzymology , Hepacivirus/physiology , Humans , Indoles/pharmacokinetics , Indoles/pharmacology , Macaca mulatta , Mice , Mice, SCID , Mice, Transgenic , Models, Molecular , Molecular Structure , Oxazocines/pharmacokinetics , Oxazocines/pharmacology , Rats , Rats, Sprague-Dawley , Stereoisomerism , Structure-Activity Relationship , Viremia/drug therapy , Viremia/virology , Virus Replication/drug effectsABSTRACT
A series of 2-(3-thienyl)-5,6-dihydroxypyrimidine-4-carboxylic acid inhibitors of the hepatitis C virus (HCV) NS5B polymerase enzyme are reported. Sulfonyl urea substituted analogs in this series proved to be the most potent active site non-nucleoside inhibitors of NS5B reported to date. These compounds had low nanomolar enzyme inhibition across HCV genotypes 1-3 and showed single digit micromolar inhibition in the HCV replicon assay. This improved cell-based activity allowed the binding mode of these compounds to be probed by selection of resistant mutations against compound 21. The results generated are in broad agreement with the previously proposed binding model for this compound class.
Subject(s)
Antiviral Agents/chemistry , Carboxylic Acids/chemistry , Enzyme Inhibitors/chemistry , Hepacivirus/enzymology , RNA-Dependent RNA Polymerase/antagonists & inhibitors , Viral Nonstructural Proteins/metabolism , Antiviral Agents/chemical synthesis , Antiviral Agents/pharmacology , Carboxylic Acids/chemical synthesis , Carboxylic Acids/pharmacology , Catalytic Domain , Cell Line, Tumor , Computer Simulation , Enzyme Inhibitors/chemical synthesis , Enzyme Inhibitors/pharmacology , Humans , RNA-Dependent RNA Polymerase/metabolism , Structure-Activity Relationship , Virus Replication/drug effects , Virus Replication/geneticsABSTRACT
The RNA replication machinery of HCV is a multi-subunit membrane-associated complex. NS5A has emerged as an active component of HCV replicase, possibly involved in regulation of viral replication and resistance to the antiviral effect of interferon. We report here substituted piperazinyl-N-(aryl)benzamides as potent inhibitors of HCV replication exerted via modulation of the dimerization of NS5A.
Subject(s)
Benzamides/chemical synthesis , Hepacivirus/genetics , Hepatitis C/drug therapy , RNA-Dependent RNA Polymerase/antagonists & inhibitors , Viral Nonstructural Proteins/antagonists & inhibitors , Viral Nonstructural Proteins/chemistry , Antiviral Agents/chemistry , Benzamides/pharmacology , Crystallography, X-Ray/methods , Dimerization , Hepacivirus/physiology , Humans , Interferons/chemistry , Models, Chemical , Molecular Conformation , Mutation , Structure-Activity RelationshipABSTRACT
We report the evolutionary path from an open-chain series to conformationally constrained tetracyclic indole inhibitors of HCV NS5B-polymerase, where the C2 aromatic is tethered to the indole nitrogen. SAR studies led to the discovery of zwitterionic compounds endowed with good intrinsic enzyme affinity and cell-based potency, as well as superior DMPK profiles to their acyclic counterparts, and ultimately to the identification of a pre-clinical candidate with an excellent predicted human pharmacokinetic profile.
Subject(s)
Chemistry, Pharmaceutical/methods , Enzyme Inhibitors/chemical synthesis , Viral Nonstructural Proteins/antagonists & inhibitors , Allosteric Site , Animals , Drug Design , Enzyme Inhibitors/pharmacology , Hepacivirus , Humans , Hydrolysis , Indoles/chemistry , Models, Chemical , Nitrogen/chemistry , Protein Conformation , Rats , Structure-Activity RelationshipABSTRACT
Allosteric inhibition of the hepatitis C virus (HCV) NS5B RNA-dependent RNA polymerase enzyme has recently emerged as a viable strategy toward blocking replication of viral RNA in cell-based systems. We report here 2 series of indole-N-acetamides, bearing physicochemically diverse carboxylic acid replacements, which show potent affinity for the NS5B enzyme with reduced potential for formation of glucuronide conjugates. Preliminary optimization of these series furnished compounds that are potent in the blockade of subgenomic HCV RNA replication in HUH-7 cells.
Subject(s)
Carboxylic Acids/chemistry , Enzyme Inhibitors/chemistry , Indoleacetic Acids/chemistry , Indoleacetic Acids/pharmacology , Viral Nonstructural Proteins/antagonists & inhibitors , Cell Line , Enzyme Inhibitors/pharmacology , HumansABSTRACT
Thieno[3,2-b]pyrroles are a novel class of allosteric inhibitors of HCV NS5B RNA-dependent RNA polymerase which show potent affinity for the NS5B enzyme. Introduction of a polar substituent in the position N1 led to a compound that efficiently blocks subgenomic HCV RNA replication in HUH-7 cells with an EC50 of 2.9 microM.