Asunto(s)
Antivirales/química , Hepacivirus/efectos de los fármacos , Hepatitis C/tratamiento farmacológico , Nucleósidos/química , Nucleótidos/química , ARN Polimerasa Dependiente del ARN/antagonistas & inhibidores , Proteínas no Estructurales Virales/antagonistas & inhibidores , Sitio Alostérico , Animales , Antivirales/farmacología , Antivirales/uso terapéutico , Dominio Catalítico , Ensayos Clínicos como Asunto , Evaluación Preclínica de Medicamentos , Genoma Viral , Hepacivirus/enzimología , Hepacivirus/genética , Hepatitis C/virología , Humanos , Modelos Moleculares , Nucleósidos/farmacología , Nucleósidos/uso terapéutico , Nucleótidos/farmacología , Nucleótidos/uso terapéutico , Profármacos/química , Profármacos/farmacología , Conformación Proteica , ARN Polimerasa Dependiente del ARN/química , Proteínas no Estructurales Virales/químicaRESUMEN
PSI-353661, a phosphoramidate prodrug of 2'-deoxy-2'-fluoro-2'-C-methylguanosine-5'-monophosphate, is a highly active inhibitor of genotype 1a, 1b, and 2a HCV RNA replication in the replicon assay and of genotype 1a and 2a infectious virus replication. PSI-353661 is active against replicons harboring the NS5B S282T or S96T/N142T amino acid alterations that confer decreased susceptibility to nucleoside/tide analogs as well as mutations that confer resistance to non-nucleoside inhibitors of NS5B. Replicon clearance studies show that PSI-353661 was able to clear cells of HCV replicon RNA and prevent a rebound in replicon RNA. PSI-353661 showed no toxicity toward bone marrow stem cells or mitochondrial toxicity. The metabolism to the active 5'-triphosphate involves hydrolysis of the carboxyl ester by cathepsin A (Cat A) and carboxylesterase 1 (CES1) followed by a putative nucleophilic attack on the phosphorus by the carboxyl group resulting in the elimination of phenol and the alaninyl phosphate metabolite, PSI-353131. Histidine triad nucleotide-binding protein 1 (Hint 1) then removes the amino acid moiety, which is followed by hydrolysis of the methoxyl group at the O(6)-position of the guanine base by adenosine deaminase-like protein 1 (ADAL1) to give 2'-deoxy-2'-fluoro-2'-C-methylguanosine-5'-monophosphate. The monophosphate is phosphorylated to the diphosphate by guanylate kinase. Nucleoside diphosphate kinase is the primary enzyme involved in phosphorylation of the diphosphate to the active triphosphate, PSI-352666. PSI-352666 is equally active against wild-type NS5B and NS5B containing the S282T amino acid alteration.