ABSTRACT
MK-8591 (4'-ethynyl-2-fluoro-2'-deoxyadenosine) is a novel nucleoside analog that displays a differentiated mechanism of action as a nucleoside reverse transcriptase translocation inhibitor (NRTTI) compared to approved NRTIs. Herein, we describe our recent efforts to explore the impact of structural changes to the properties of MK-8591 through the synthesis and antiviral evaluation of carbocyclic derivatives. Synthesized analogs were evaluated for their antiviral activity, and the corresponding triphosphates were synthesized and evaluated in a biochemical assay. 4'-Ethynyl-G derivative (±)-29 displayed a promising IC50 of 33 nM in a hPBMC cell-based antiviral assay, and its triphosphate (TP), (±)-29-TP, displayed an IC50 of 324 nM in a biochemical RT-polymerase assay. Improved TP anabolite delivery resulting in improved in vitro potency was achieved by preparing the corresponding phosphoramidate prodrug of single enantiomer 29b, with 6-ethoxy G derivative 34b displaying a significantly improved IC50 of 3.0 nM, paving the way for new directions for this novel class of nucleoside analogs.
Subject(s)
Antiviral Agents/chemical synthesis , Antiviral Agents/pharmacology , Deoxyadenosines/chemical synthesis , Deoxyadenosines/pharmacology , Reverse Transcriptase Inhibitors/chemical synthesis , Reverse Transcriptase Inhibitors/pharmacology , Animals , Antiviral Agents/metabolism , Antiviral Agents/pharmacokinetics , Cell Line , Chemistry Techniques, Synthetic , Deoxyadenosines/metabolism , Deoxyadenosines/pharmacokinetics , HIV Reverse Transcriptase/antagonists & inhibitors , HIV Reverse Transcriptase/chemistry , HIV Reverse Transcriptase/metabolism , HIV-1/drug effects , HIV-1/enzymology , Humans , Inhibitory Concentration 50 , Molecular Docking Simulation , Protein Conformation , Rats , Reverse Transcriptase Inhibitors/metabolism , Reverse Transcriptase Inhibitors/pharmacokinetics , Tissue DistributionABSTRACT
Herein we describe the discovery of IDX21437 35b, a novel RPd-aminoacid-based phosphoramidate prodrug of 2'-α-chloro-2'-ß-C-methyluridine monophosphate. Its corresponding triphosphate 6 is a potent inhibitor of the HCV NS5B RNA-dependent RNA polymerase (RdRp). Despite showing very weak activity in the in vitro Huh-7 cell based HCV replicon assay, 35b demonstrated high levels of active triphosphate 6 in mouse liver and human hepatocytes. A biochemical study revealed that the metabolism of 35b was mainly attributed to carboxyesterase 1 (CES1), an enzyme which is underexpressed in HCV Huh-7-derived replicon cells. Furthermore, due to its metabolic activation, 35b was efficiently processed in liver cells compared to other cell types, including human cardiomyocytes. The selected RP diastereoisomeric configuration of 35b was assigned by X-ray structural determination. 35b is currently in Phase II clinical trials for the treatment of HCV infection.
Subject(s)
Antiviral Agents/pharmacology , DNA-Directed RNA Polymerases/antagonists & inhibitors , Drug Discovery , Enzyme Inhibitors/pharmacology , Hepacivirus/drug effects , Uridine Monophosphate/analogs & derivatives , Uridine/pharmacology , Animals , Antiviral Agents/chemical synthesis , Antiviral Agents/chemistry , DNA-Directed RNA Polymerases/metabolism , Dose-Response Relationship, Drug , Enzyme Inhibitors/chemical synthesis , Enzyme Inhibitors/chemistry , Hepacivirus/enzymology , Hepatocytes/drug effects , Hepatocytes/virology , Humans , Liver/drug effects , Liver/virology , Mice , Microbial Sensitivity Tests , Molecular Structure , Structure-Activity Relationship , Uridine/chemical synthesis , Uridine/chemistry , Uridine Monophosphate/chemical synthesis , Uridine Monophosphate/chemistry , Uridine Monophosphate/pharmacology , Viral Nonstructural Proteins/antagonists & inhibitors , Viral Nonstructural Proteins/metabolismABSTRACT
Exploration of the P2 region by mimicking the proline motif found in BILN2061 resulted in the discovery of two series of potent HCV NS3/4A protease inhibitors. X-ray crystal structure of the ligand in contact with the NS3/4A protein and modulation of the quinoline heterocyclic region by structure based design and modeling allowed for the optimization of enzyme potency and cellular activity. This research led to the selection of clinical candidate IDX320 having good genotype coverage and pharmacokinetic properties in various species.
Subject(s)
Drug Discovery , Hepacivirus/drug effects , Macrocyclic Compounds/chemistry , Macrocyclic Compounds/pharmacology , Viral Nonstructural Proteins/antagonists & inhibitors , Animals , Haplorhini , Hepatocytes/enzymology , Humans , Inhibitory Concentration 50 , Mice , Microsomes, Liver/enzymology , Molecular Structure , Rats , Rats, Sprague-Dawley , Serine Proteinase Inhibitors/chemical synthesis , Serine Proteinase Inhibitors/chemistry , Serine Proteinase Inhibitors/pharmacology , Viral Nonstructural Proteins/chemistryABSTRACT
We disclose here the synthesis of a series of macrocyclic HCV protease inhibitors, where the homoserine linked together the quinoline P2' motif and the macrocyclic moiety. These compounds exhibit potent inhibitory activity against HCV NS3/4A protease and replicon cell based assay. Their enzymatic and antiviral activities are modulated by substitutions on the quinoline P2' at position 8 by methyl and halogens and by small heterocycles at position 2. The in vitro structure activity relationship (SAR) studies and in vivo pharmacokinetic (PK) evaluations of selected compounds are described herein.
Subject(s)
Antiviral Agents/chemical synthesis , Antiviral Agents/pharmacology , Hepacivirus/drug effects , Homoserine/pharmacology , Serine Proteinase Inhibitors/chemical synthesis , Serine Proteinase Inhibitors/pharmacology , Viral Nonstructural Proteins/antagonists & inhibitors , Antiviral Agents/chemistry , Dose-Response Relationship, Drug , Hepacivirus/enzymology , Homoserine/chemical synthesis , Homoserine/chemistry , Microbial Sensitivity Tests , Molecular Structure , Serine Proteinase Inhibitors/chemistry , Structure-Activity Relationship , Viral Nonstructural Proteins/metabolismABSTRACT
Structural homology between thrombin inhibitors and the early tetrapeptide HCV protease inhibitor led to the bioisosteric replacement of the P2 proline by a 2,4-disubstituted azetidine within the macrocyclic ß-strand mimic. Molecular modeling guided the design of the series. This approach was validated by the excellent activity and selectivity in biochemical and cell based assays of this novel series and confirmed by the co-crystal structure of the inhibitor with the NS3/4A protein (PDB code: 4TYD).
Subject(s)
Azetidines/pharmacology , Drug Design , Serine Proteinase Inhibitors/pharmacology , Viral Nonstructural Proteins/antagonists & inhibitors , Azetidines/chemical synthesis , Azetidines/chemistry , Crystallography, X-Ray , Dose-Response Relationship, Drug , Models, Molecular , Molecular Structure , Serine Proteinase Inhibitors/chemical synthesis , Serine Proteinase Inhibitors/chemistry , Structure-Activity Relationship , Viral Nonstructural Proteins/metabolismABSTRACT
A functional screening highlighted a series of spiro-piperidines as 5-HT2B receptor antagonists. Preliminary structure-activity relationship has been explored driving to potent antagonists (IC50 = 1 nM) and indicating directions for further explorations.
