ABSTRACT
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.
Subject(s)
Antiviral Agents/chemical synthesis , Azides/chemical synthesis , Hepacivirus/drug effects , Organophosphorus Compounds/chemical synthesis , Uridine/analogs & derivatives , Antiviral Agents/chemistry , Antiviral Agents/pharmacology , Azides/chemistry , Azides/pharmacology , Cell Line, Tumor , Hepacivirus/genetics , Humans , Models, Molecular , Organophosphorus Compounds/chemistry , Organophosphorus Compounds/pharmacology , Replicon , Stereoisomerism , Structure-Activity Relationship , Uridine/chemical synthesis , Uridine/chemistry , Uridine/pharmacologyABSTRACT
Bicyclic furanopyrimidine nucleoside analogues (BCNAs) have been previously reported as potent and selective anti-varicella-zoster virus (VZV) agents. Few modifications on the sugar moiety have been considered so far but some of them have shown interesting activity against human cytomegalovirus (HCMV) while losing activity against VZV. In addition, recent work has led to an entirely new series of anti-HCMV bicyclic furopyrimidine agents, acting through a non-nucleoside mechanism. In order to further investigate structure-activity relationship studies on the sugar moiety, some 3'- and 5'-chloro derivatives and 5'-deoxygenated derivatives have been synthesized. The lack of anti-VZV activity of the 5'-modified derivatives is further proof of a mechanism of action involving VZV thymidine kinase (TK)-mediated phosphorylation. Similarly, the replacement of the 3'-OH with chlorine showed a decrease of antiviral activity, which can be correlated to the lack of interaction with VZV TK as demonstrated by enzyme assays. These results confirm free 5'-OH and 3'-OH as necessary requirements for efficient recognition by VZV TK and for potent anti-VZV activity in cell culture.
