RESUMO
The NS5B RNA-dependent RNA polymerase (RdRp) is a key enzyme for Hepatitis C Virus (HCV) replication. In addition to the catalytic site, this enzyme is characterized by the presence of at least four allosteric pockets making it an interesting target for development of inhibitors as potential anti-HCV drugs. Based on a previous study showing the potential of the naturally occurring aurones as inhibitors of NS5B, we pursued our efforts to focus on pseudodimeric aurones that have never been investigated so far. Hence, 14 original compounds characterized by the presence of a spacer between the benzofuranone moieties were synthesized and investigated as HCV RdRp inhibitors by means of an in vitro assay. The most active inhibitor, pseudodimeric aurone 4, induced high inhibition activity (IC50 = 1.3 µM). Mutagenic and molecular modeling studies reveal that the binding site for the most active derivatives probably is the palm pocket I instead of the thumb pocket I as for the monomeric derivatives.
Assuntos
Antivirais/farmacologia , Benzofuranos/farmacologia , Inibidores Enzimáticos/farmacologia , Hepacivirus/enzimologia , RNA Polimerase Dependente de RNA/antagonistas & inibidores , Proteínas não Estruturais Virais/antagonistas & inibidores , Antivirais/síntese química , Antivirais/química , Benzofuranos/síntese química , Benzofuranos/química , Relação Dose-Resposta a Droga , Inibidores Enzimáticos/síntese química , Inibidores Enzimáticos/química , Testes de Sensibilidade Microbiana , Estrutura Molecular , RNA Polimerase Dependente de RNA/metabolismo , Relação Estrutura-Atividade , Proteínas não Estruturais Virais/metabolismoRESUMO
Following our recent report showing the potential of naturally occurring aurones (2-benzylidenebenzofuran-3(2H)-ones) as anti-hepatitis C virus (HCV) agents, efforts were continued in order to refine the structural requirements for the inhibitory effect on HCV RNA-dependent RNA polymerase (RdRp). In this study, we targeted the B-ring moiety of aurones with the aim to improve structural features associated with higher inhibition of the targeted polymerase. In vitro evaluation of the RdRp inhibitory activity of the 37 newly synthesized compounds pointed out that the replacement of the B-ring with an N-substituted indole moiety induced the highest inhibitory effect. Of these, compounds 31, 40 and 41 were found to be the most active (IC50 = 2.3-2.4 µM). Docking experiments performed with the most active compounds revealed that the allosteric thumb pocket I of RdRp is the binding pocket for aurone analogues.
