A Novel Small Molecule Inhibitor of Hepatitis C Virus Entry

Small molecule inhibitors of hepatitis C virus (HCV) are being developed to complement or replace treatments with pegylated interferons and ribavirin, which have poor response rates and significant side effects. Resistance to these inhibitors emerges rapidly in the clinic, suggesting that successful therapy will involve combination therapy with multiple inhibitors of different targets. The entry process of HCV into hepatocytes represents another series of potential targets for therapeutic intervention, involving viral structural proteins that have not been extensively explored due to experimental limitations. To discover HCV entry inhibitors, we utilized HCV pseudoparticles (HCVpp) incorporating E1-E2 envelope proteins from a genotype 1b clinical isolate. Screening of a small molecule library identified a potent HCV-specific triazine inhibitor, EI-1. A series of HCVpp with E1-E2 sequences from various HCV isolates was used to show activity against all genotype 1a and 1b HCVpp tested, with median EC50 values of 0.134 and 0.027 µM, respectively. Time-of-addition experiments demonstrated a block in HCVpp entry, downstream of initial attachment to the cell surface, and prior to or concomitant with bafilomycin inhibition of endosomal acidification. EI-1 was equally active against cell-culture adapted HCV (HCVcc), blocking both cell-free entry and cell-to-cell transmission of virus. HCVcc with high-level resistance to EI-1 was selected by sequential passage in the presence of inhibitor, and resistance was shown to be conferred by changes to residue 719 in the carboxy-terminal transmembrane anchor region of E2, implicating this envelope protein in EI-1 susceptibility. Combinations of EI-1 with interferon, or inhibitors of NS3 or NS5A, resulted in additive to synergistic activity. These results suggest that inhibitors of HCV entry could be added to replication inhibitors and interferons already in development

Chemical genetics strategy identifies an HCV NS5A inhibitor with a potent clinical effect. Nature

The worldwide prevalence of chronic hepatitis C virus (HCV) infection is estimated to be approaching 200 million people We designed a mechanistically unbiased approach based on chemical genetics to identify chemical starting points for interfering with HCV replication. Our differentiating strategy centred on the identification of compounds functionally distinct from those acting on the traditional targets of antiviral research in this field, the NS3 protease and the NS5B RNA-dependent RNA polymerase 10 . BMS-858 formed the basis of an extensive series of chemical refinements that focused on improving antiviral potency, broadening inhibitory activity to encompass the HCV 1a genotype, and optimizing for oral bioavailability and sustained pharmacokinetic properties. After defining symmetry as an important contributor to antiviral activity 10 , a discovery that preceded the disclosure of structural information (see below), we subsequently identified BMS-79005

Electrophilic Hydrazination of Cyclopropanols Using Azodicarboxylates via Copper(II) Catalysis: An Umpolung Strategy to Access β‑Hydrazino Ketone Motifs

The scope of an umpolung approach to expand synthetic access to bifunctional γ-keto hydrazine intermediates via electrophilic amination of β-homoenolates derived from cyclopropanol precursors that took advantage of azodicarboxylates or azodicarboxamides as electron-deficient nitrogen sources was examined. This new synthetic procedure avails commercially available or readily accessible starting materials along with a ligand-free Cu(II) salt as an inexpensive catalyst. Using this operationally simple reaction, which proceeds under mild conditions (open-flask and ambient temperature) and is suitable for multigram scale, preparative applications were established with a range of aryl- and alkyl-substituted cyclopropanols and azodicarboxylate/azodicarboxamide substrates (26 examples, 74–95% yields). Further, the obtained products have been shown to provide convenient synthetic access to γ-hydroxy hydrazide, γ-amino hydrazide, and heterocyclic derivatives