Development of an improved inhibitor of Lats kinases to promote regeneration of mammalian organs.

The Hippo signaling pathway acts as a brake on regeneration in many tissues. This cascade of kinases culminates in the phosphorylation of the transcriptional cofactors Yap and Taz, whose concentration in the nucleus consequently remains low. Various types of cellular signals can reduce phosphorylation, however, resulting in the accumulation of Yap and Taz in the nucleus and subsequently in mitosis.

PTC725, an NS4B-Targeting Compound, Inhibits a Hepatitis C Virus Genotype 3 Replicon, as Predicted by Genome Sequence Analysis and Determined Experimentally.

PTC725 is a small molecule NS4B-targeting inhibitor of hepatitis C virus (HCV) genotype (gt) 1 RNA replication that lacks activity against HCV gt2. We analyzed the Los Alamos HCV sequence database to predict susceptible/resistant HCV gt's according to the prevalence of known resistance-conferring amino acids in the NS4B protein. Our analysis predicted that HCV gt3 would be highly susceptible to the activity of PTC725.

Discovery of 2-(4-sulfonamidophenyl)-indole 3-carboxamides as potent and selective inhibitors with broad hepatitis C virus genotype activity targeting HCV NS4B.

A novel series of 2-(4-sulfonamidophenyl)-indole 3-carboxamides was identified and optimized for activity against the HCV genotype 1b replicon resulting in compounds with potent and selective activity. Further evaluation of this series demonstrated potent activity across HCV genotypes 1a, 2a and 3a. Compound 4z had reduced activity against HCV genotype 1b replicons containing single mutations in the NS4B coding sequence (F98C and V105M) indicating that NS4B is the target.

The introduction of P4 substituted 1-methylcyclohexyl groups into Boceprevir: a change in direction in the search for a second generation HCV NS3 protease inhibitor.

In the search for a second generation HCV protease inhibitor, molecular modeling studies of the X-ray crystal structure of Boceprevir1 bound to the NS3 protein suggest that expansion into the S4 pocket could provide additional hydrophobic Van der Waals interactions. Effective replacement of the P4 tert-butyl with a cyclohexylmethyl ligand led to inhibitor 2 with improved enzyme and replicon activities. Subsequent modeling and SAR studies led to the pyridine 38 and sulfone analogues 52 and 53 with vastly improved PK parameters in monkeys, forming a new foundation for further exploration.

Discovery of novel P3 sulfonamide-capped inhibitors of HCV NS3 protease. Inhibitors with improved cellular potencies.

Hepatitis C Virus (HCV) infection is the major cause of chronic liver disease, leading to cirrhosis and hepatocellular carcinoma, which affects more than 200 million people worldwide. Currently the only therapeutic regimens are subcutaneous interferon-alpha or PEG-interferon alone or in combination with oral ribavirin. Although combination therapy is reasonably successful with the majority of genotypes, its efficacy against the predominant genotype (genotype 1) is moderate at best, with only approximately 50% of the patients showing sustained virological response.

Design, synthesis, and evaluation of oxygen-containing macrocyclic peptidomimetics as inhibitors of HCV NS3 protease.

HCV infection is considered a silent epidemic because most people infected do not develop acute symptoms. Instead, the disease progresses to a chronic state leading to cirrhosis and hepatocarcinoma. Novel therapies are needed to combat this major health threat.

Discovery and structure-activity relationship of P1-P3 ketoamide derived macrocyclic inhibitors of hepatitis C virus NS3 protease.

Hepatitis C virus (HCV) infection is the major cause of chronic liver disease, leading to cirrhosis and hepatocellular carcinoma, and affects more than 200 million people worldwide. Although combination therapy of interferon-alpha and ribavirin is reasonably successful in treating majority of genotypes, its efficacy against the predominant genotype (genotype 1) is moderate at best, with only about 40% of the patients showing sustained virological response. Herein, the SAR leading to the discovery of a series of ketoamide derived P(1)-P(3) macrocyclic inhibitors that are more potent than the first generation clinical candidate, boceprevir (1, Sch 503034), is discussed.

Key steps in the structure-based optimization of the hepatitis C virus NS3/4A protease inhibitor SCH503034.

The structures of both native and S139A holo-HCV NS3/4A protease domain were solved to high resolution. Subsequently, structures were determined for a series of ketoamide inhibitors in complex with the protease. The changes in the inhibitor potency were correlated with changes in the buried surface area upon binding the inhibitor to the active site.

Correlation between PAMPA permeability and cellular activities of hepatitis C virus protease inhibitors.

Parallel artificial membrane permeability assay (PAMPA) and Caco-2 cells have been frequently used for the evaluation of in vitro permeability of new chemical entities. In this study we evaluated the correlation between permeability, assessed by both methods, and the cellular potency of 34 novel hepatitis C virus (HCV) protease inhibitors. Two types of assays were used to determine the potency of HCV protease inhibitors: a cell-free assay that evaluates the intrinsic affinity (K(i)) between the protease and the inhibitor and a cell-based replicon assay that determines the inhibitors' IC90.

Potent and selective small molecule NS3 serine protease inhibitors of Hepatitis C virus with dichlorocyclopropylproline as P2 residue.

Starting from a pentapeptide Hepatitis C virus NS3 protease inhibitor, a number of alpha-ketoamide inhibitors based on novel dichlorocyclopropylproline P2 core were synthesized and investigated for their HCV NS3 serine protease activity. The key intermediate 3,4-dichlorocyclopropylproline was obtained through a dichloro carbene insertion to 3,4-dehydroproline. The size of the molecules was reduced significantly through a series of truncations of the initial pentapeptide.

A high-throughput assay for the adenylation reaction of bacterial DNA ligase.

DNA ligase catalyzes the closure of single-strand nicks in double-stranded DNA that arise during replication and recombination. Inhibition of bacterial ligase is expected to cause chromosome degradation and cell death, making it an attractive target for new antibacterials. The prototypical bacterial ligase couples the hydrolysis of NAD(+) to phosphodiester bond formation between an adjacent 3'OH and 5'-terminal phosphate of nicked duplex DNA.

Discovery of the HCV NS3/4A protease inhibitor (1R,5S)-N-[3-amino-1-(cyclobutylmethyl)-2,3-dioxopropyl]-3- [2(S)-[[[(1,1-dimethylethyl)amino]carbonyl]amino]-3,3-dimethyl-1-oxobutyl]- 6,6-dimethyl-3-azabicyclo[3.1.0]hexan-2(S)-carboxamide (Sch 503034) II. Key steps in structure-based optimization.

The structures of both the native holo-HCV NS3/4A protease domain and the protease domain with a serine 139 to alanine (S139A) mutation were solved to high resolution. Subsequently, structures were determined for a series of ketoamide inhibitors in complex with the protease. The changes in the inhibitor potency were correlated with changes in the buried surface area upon binding the inhibitor to the active site.

In vitro antiviral activity of SCH446211 (SCH6), a novel inhibitor of the hepatitis C virus NS3 serine protease.

Background: Current hepatitis C virus (HCV) therapies may cure approximately 60% of infections. They are often contraindicated or poorly tolerated, underscoring the need for safer and more effective drugs. A novel, alpha-ketoamide-derived, substrate-based inhibitor of the HCV serine protease (SCH446211) was developed.

Discovery of (1R,5S)-N-[3-amino-1-(cyclobutylmethyl)-2,3-dioxopropyl]- 3-[2(S)-[[[(1,1-dimethylethyl)amino]carbonyl]amino]-3,3-dimethyl-1-oxobutyl]- 6,6-dimethyl-3-azabicyclo[3.1.0]hexan-2(S)-carboxamide (SCH 503034), a selective, potent, orally bioavailable hepatitis C virus NS3 protease inhibitor: a potential therapeutic agent for the treatment of hepatitis C infection.

Hepatitis C virus (HCV) infection is the major cause of chronic liver disease, leading to cirrhosis and hepatocellular carcinoma, which affects more than 170 million people worldwide. Currently the only therapeutic regimens are subcutaneous interferon-alpha or polyethylene glycol (PEG)-interferon-alpha alone or in combination with oral ribavirin. Although combination therapy is reasonably successful with the majority of genotypes, its efficacy against the predominant genotype (genotype 1) is moderate at best, with only about 40% of the patients showing sustained virological response.

P2-P4 macrocyclic inhibitors of hepatitis C virus NS3-4A serine protease.

Synthesis and HCV NS3 serine protease inhibitory activity of 4-hydroxyproline derived macrocyclic inhibitors and SAR around this macrocyclic core is described in this communication. X-ray structure of inhibitor 38 bound to the protease is discussed.

Discovery of SCH446211 (SCH6): a new ketoamide inhibitor of the HCV NS3 serine protease and HCV subgenomic RNA replication.

Introduction of various modified prolines at P(2) and optimization of the P(1) side chain led to the discovery of SCH6 (24, Table 2), a potent ketoamide inhibitor of the HCV NS3 serine protease. In addition to excellent enzyme potency (K(i)*= 3.8 nM), 24 was also found to be a potent inhibitor of HCV subgenomic RNA replication with IC(50) and IC(90) of 40 and 100 nM, respectively.

Novel potent hepatitis C virus NS3 serine protease inhibitors derived from proline-based macrocycles.

The hepatitis C virus (HCV) NS3 protease is essential for viral replication. It has been a target of choice for intensive drug discovery research. On the basis of an active pentapeptide inhibitor, 1, we envisioned that macrocyclization from the P2 proline to P3 capping could enhance binding to the backbone Ala156 residue and the S4 pocket.

Potent 7-hydroxy-1,2,3,4-tetrahydroisoquinoline-3-carboxylic acid-based macrocyclic inhibitors of hepatitis C virus NS3 protease.

The NS3 protease of hepatitis C virus (HCV) has emerged as one of the best characterized targets for next-generation HCV therapy. The tetrapeptide 1 and pentapeptide 2 are alpha-ketoamide-type HCV serine protease inhibitors with modest potency. We envisioned that the 1,2,3,4-tetrahydroisoquinoline-3-carboxylamide (Tic) moiety could be cyclized to the P3 capping group.

Novel inhibitors of hepatitis C NS3-NS4A serine protease derived from 2-aza-bicyclo[2.2.1]heptane-3-carboxylic acid.

Prolonged hepatitis C infection is the leading cause for cirrhosis of the liver and hepatocellular carcinoma. The etiological agent HCV virus codes a single polyprotein of approximately 3000 amino acids that is processed with the help of a serine protease NS3A to produce structural and non-structural proteins required for viral replication. Inhibition of NS3 protease can potentially be used to develop drugs for treatment of HCV infections.

Depeptidization efforts on P3-P2' alpha-ketoamide inhibitors of HCV NS3-4A serine protease: effect on HCV replicon activity.

Depeptidization efforts of the P(3)-P(2) region of P(3) capped alpha-ketoamide inhibitor of HCV NS3 serine protease 1 are reported. We clearly established that N-methylation of the P(2) nitrogen and modification of the P(2)' carboxylic acid terminus were essential for activity in the replicon assay.

Design, synthesis, and biological activity of m-tyrosine-based 16- and 17-membered macrocyclic inhibitors of hepatitis C virus NS3 serine protease.

The limited efficacy and considerable side effects of currently available therapies for the treatment of hepatitis C virus (HCV) infection have prompted significant efforts toward the development of safe and effective new therapeutics. The pentapeptide alpha-ketoamides of type 1 were weak HCV inhibitors with a binding constant, Ki, above 5 microM. We envisioned that cyclization of a P2 phenyl side chain to a P3 capping group could enhance binding through an interaction of the resulting macrocycle with the methyl group of Ala156 on the enzyme backbone.

Synthesis and biological activity of macrocyclic inhibitors of hepatitis C virus (HCV) NS3 protease.

The 17-membered phenylalanine-based macrocycle 6 was prepared starting from 3-iodo-phenylalanine. Macrocyclization of alkene phenyl iodide 5 was effected through a palladium-catalyzed Heck reaction. The macrocyclic alpha-ketoamides were active inhibitors of the HCV NS3 protease, with the C-terminal acids and amides being more potent than tert-butyl esters.

Novel inhibitors of the hepatitis C virus NS3 proteinase.

The hepatitis C virus proteinase inhibitor 4-methyl-1-(phenylmethyl)-2,6-pyridinedione 1 undergoes a novel autoxidation process, on silica gel, leading to the dimer 2 as the major product, a relatively more potent inhibitor of the enzyme.

Design and synthesis of depeptidized macrocyclic inhibitors of hepatitis C NS3-4A protease using structure-based drug design.

Hepatitis C virus (HCV) NS3, when bound to NS-4A cofactor, facilitates development of mature virons by catalyzing cleavage of a polyprotein to form functional and structural proteins of HCV. The enzyme has a shallow binding pocket at the catalytic site, making development of inhibitors difficult. We have designed, preorganized, and depeptidized macrocyclic inhibitors from P(4) to P(2)' and optimized binding to 0.