ABSTRACT
We report the design, synthesis and evaluation of a family of ca 50 phosphoramidate ProTides of the potent anti-HCV compound 4'-azidocytidine (R1479), with variation on the ester, amino acid and aryl moiety of the ProTide. Sub-muM inhibitors of HCV emerge. The compounds are all non-cytotoxic in the replicon assay. We herein report detailed SARs for each of the regions of the ProTide.
Subject(s)
Antiviral Agents/chemical synthesis , Chemistry, Pharmaceutical/methods , Cytidine/analogs & derivatives , Hepacivirus/metabolism , Hepatitis C/drug therapy , Technology, Pharmaceutical/methods , Amino Acids/chemistry , Antiviral Agents/pharmacology , Cytidine/chemical synthesis , Cytidine/pharmacology , Drug Design , Drug Evaluation, Preclinical , Humans , Models, Chemical , Prodrugs , Replicon/drug effects , Virus ReplicationABSTRACT
Beta-2'-C-methyl purines (1, 2) are known inhibitors of hepatitis C virus (HCV). We herein report the synthesis, biological and enzymatic evaluation of their 5'-phosphoramidate ProTides. Described herein are seven l-alanine phosphoramidate derivatives with variations to the amino acid ester. The 1-naphthyl phosphoramidate of beta-2'-methylguanosine containing the benzyl ester (20) was the most active at 0.12microM, an 84-fold of increase in activity compared to the parent nucleoside (2) with no increase of cytotoxicity. The carboxypeptidase mediated hydrolysis of several ProTides showed a predictive correlation with their activity versus HCV in replicon.
Subject(s)
Amides/chemistry , Antiviral Agents/chemical synthesis , Chemistry, Pharmaceutical/methods , Guanosine/analogs & derivatives , Hepacivirus/metabolism , Hepatitis C/drug therapy , Phosphoric Acids/chemistry , Amino Acids/chemistry , Antiviral Agents/pharmacology , Drug Design , Esters/chemistry , Guanosine/chemistry , Guanosine/pharmacology , Humans , Hydrolysis , Magnetic Resonance Spectroscopy , Models, Chemical , ProdrugsABSTRACT
We report on the synthesis of the anti hepatitis C virus (HCV) agent 4'-azidoadenosine (1) and the application of the phosphoramidate ProTide technology to this nucleoside. The synthesis of 1 was achieved through an epoxide intermediate followed by regio- and stereoselective ring opening by azidotrimethylsilane in the presence of a Lewis acid. Compound 1 did not inhibit HCV replication in cell culture at concentrations up to 0.1 mM. However, a submicromolar active agent could be derived from 1 by the application of the ProTide technology. All the phosphoramidates prepared were L-alanine derivatives with variations in the aryl moiety and in the ester part of the amino acid. The benzyl ester and the l-naphthyl phosphate (18) had the best activity in replicon assay. Phosphoramidates (18-21) achieved a significant improvement in antiviral potency over the parent nucleoside (1) with no increase in cytotoxicity.
Subject(s)
Adenosine/analogs & derivatives , Adenosine/chemical synthesis , Antiviral Agents/chemical synthesis , Azides/chemical synthesis , Hepacivirus/drug effects , Organophosphorus Compounds/chemical synthesis , Adenosine/pharmacology , Antiviral Agents/pharmacology , Azides/pharmacology , Cells, Cultured , Hepacivirus/physiology , Humans , Organophosphorus Compounds/pharmacology , Replicon , Stereoisomerism , Structure-Activity Relationship , Virus Replication/drug effectsABSTRACT
We report the application of our phosphoramidate ProTide technology to the ribonucleoside analogue 4'-azidouridine to generate novel antiviral agents for the inhibition of hepatitis C virus (HCV). 4'-Azidouridine did not inhibit HCV, although 4'-azidocytidine was a potent inhibitor of HCV replication under similar assay conditions. However 4'-azidouridine triphosphate was a potent inhibitor of RNA synthesis by HCV polymerase, raising the question as to whether our phosphoramidate ProTide approach could effectively deliver 4'-azidouridine monophosphate to HCV replicon cells and unleash the antiviral potential of the triphosphate. Twenty-two phosphoramidates were prepared, including variations in the aryl, ester, and amino acid regions. A number of compounds showed sub-micromolar inhibition of HCV in cell culture without detectable cytotoxicity. These results confirm that phosphoramidate ProTides can deliver monophosphates of ribonucleoside analogues and suggest a potential path to the generation of novel antiviral agents against HCV infection. The generic message is that ProTide synthesis from inactive parent nucleosides may be a warranted drug discovery strategy.
