ABSTRACT
Inhibitors of the HCV NS5A nonstructural protein are showing promising clinical potential in the treatment of hepatitis C when used in combination with other direct-acting antiviral agents. Current NS5A clinical candidates such as daclatasvir, ledipasvir, and ombitasvir share a common pharmacophore that features a pair of (S)-methoxycarbonylvaline capped pyrrolidines linked to various cores by amides, imidazoles and/or benzimidazoles. In this Letter, we describe the evaluation of NS5A inhibitors which contain alternative heteroaromatic replacements for these amide mimetics. The SAR knowledge gleaned in the optimization of scaffolds containing benzoxazoles was parlayed toward the identification of potent NS5A inhibitors containing other heteroaromatic replacements such as indoles and imidazopyridines.
Subject(s)
Antiviral Agents/chemical synthesis , Antiviral Agents/pharmacology , Hepacivirus/drug effects , Viral Nonstructural Proteins/antagonists & inhibitors , Antiviral Agents/chemistry , Structure-Activity RelationshipABSTRACT
The treatment of HCV with highly efficacious, well-tolerated, interferon-free regimens is a compelling clinical goal. Trials employing combinations of direct-acting antivirals that include NS5A inhibitors have shown significant promise in meeting this challenge. Herein, we describe our efforts to identify inhibitors of NS5A and report on the discovery of benzimidazole-containing analogs with subnanomolar potency against genotype 1a and 1b replicons. Our SAR exploration of 4-substituted pyrrolidines revealed that the subtle inclusion of a 4-methyl group could profoundly increase genotype 1a potency in multiple scaffold classes.
Subject(s)
Antiviral Agents/pharmacology , Benzimidazoles/pharmacology , Pyrrolidines/pharmacology , Viral Nonstructural Proteins/drug effects , Antiviral Agents/chemistry , Benzimidazoles/chemistry , Genotype , Pyrrolidines/chemistryABSTRACT
HCV NS5B RNA-dependent RNA polymerase (NS5B) is essential for viral replication and is therefore considered a target for antiviral drug development. From our ongoing screening effort in the search for new anti-HCV agents, a novel inhibitor 1 with low microM activity against the HCV NS5B polymerase was identified. SAR analysis indicated the optimal substitution pattern required for activity, for example, carboxylic acid group at 2-position of thiophene ring. We describe the steps taken to identify and solve the bioactive conformation of derivative 6 through the use of the transferred NOE method (trNOE).
Subject(s)
Antiviral Agents/chemical synthesis , RNA-Dependent RNA Polymerase/antagonists & inhibitors , Sulfonamides/chemical synthesis , Viral Nonstructural Proteins/antagonists & inhibitors , Antiviral Agents/chemistry , Humans , Magnetic Resonance Spectroscopy , Models, Molecular , Molecular Conformation , Pyridines/chemistry , RNA-Dependent RNA Polymerase/chemistry , Structure-Activity Relationship , Sulfonamides/chemistry , Thiophenes/chemistry , Viral Nonstructural Proteins/chemistryABSTRACT
Herein, we describe the structure-activity relationship (SAR) of N,N-disubstituted phenylalanine series of NS5B polymerase inhibitors of hepatitis C. The NS5B polymerase inhibitory activity of the most active compound exhibited an IC(50) of 2.7 microM.