Benzothiazepinecarboxamides: Novel hepatitis C virus inhibitors that interfere with viral entry and the generation of infectious virions

Upon screening synthetic small molecule libraries with the infectious hepatitis C virus (HCV) cell culture system, we identified a benzothiazepinecarboxamide (BTC) scaffold that inhibits HCV. A structure-activity relationship (SAR) study with BTCs was performed, and modifications that led to nanomolar antiviral activity and improved the selective index (CC50/EC50) by more than 1000-fold were identified. In addition, a pharmacophore modeling study determined that the tricyclic core and positive charge on the piperidine moiety were essential for antiviral activity. Furthermore, we demonstrated that BTC interferes with HCV glycoprotein E1/E2-mediated viral entry and the generation of infectious virions by using HCV pseudoparticle and cell culture supernatant transfer assays, respectively. BTC showed potent antiviral activity against HCV genotype 2 (EC50 = 0.01 ± 0.01 μM), but was less potent against a genotype 1/2 chimeric virus (EC50 = 2.71 ± 0.05 μM), which expressed the structural proteins of HCV genotype 1. In summary, we identified, optimized, and characterized novel BTC inhibitors that interfere with early and late steps of the HCV viral life cycle.