ABSTRACT
3'-Fluoro-3'-deoxythymidine (FLT) was identified as one of the most potent inhibitors of human immunodeficiency virus (HIV) replication. However, FLT also showed severe toxicity so that it was abundant as a potential chemotherapeutic agent. Here, we describe various triphosphate prodrugs of FLT aiming for (a) a bypass of all phosphorylation steps needed to convert the nucleoside analogue into its triphosphate (TP) form, (b) an intracellular delivery of hydrolytically and enzymatically stable triphosphate derivatives, and (c) increasing the selectivity for HIV-RT vs three cellular DNA polymerases including the mitochondrial DNA polymerase γ. γ-Alkylated FLTTP compounds fulfill all of these requirements because these compounds proved highly resistant to dephosphorylation and showed strong selectivity for HIV-RT. Moreover, a prodrug form of these compounds proved to be nontoxic in CEM cells.
Subject(s)
Anti-HIV Agents , HIV-1 , Prodrugs , Anti-HIV Agents/pharmacology , Anti-HIV Agents/therapeutic use , DNA Polymerase gamma , DNA-Directed DNA Polymerase , Dideoxynucleosides , HIV Reverse Transcriptase , Humans , Nucleosides/pharmacology , Polyphosphates , Prodrugs/pharmacology , Prodrugs/therapeutic use , Reverse Transcriptase Inhibitors/pharmacology , Reverse Transcriptase Inhibitors/therapeutic useABSTRACT
Herein we describe the synthesis of lipophilic triphosphate prodrugs of abacavir, carbovir, and their 1',2'-cis-substituted carbocyclic analogues. The 1',2'-cis-carbocyclic nucleosides were prepared by starting from enantiomerically pure (1R,2S)-2-((benzyloxy)methyl)cyclopent-3-en-1-ol by a microwave-assisted Mitsunobu-type reaction with 2-amino-6-chloropurine. All four nucleoside analogues were prepared from their 2-amino-6-chloropurine precursors. The nucleosides were converted into their corresponding nucleoside triphosphate prodrugs (TriPPPro approach) by application of the H-phosphonate route. The TriPPPro compounds were hydrolyzed in different media, in which the formation of nucleoside triphosphates was proven. While the TriPPPro compounds of abacavir and carbovir showed increased antiviral activity over their parent nucleoside, the TriPPPro compounds of the 1',2'-cis-substituted analogues as well as their parent nucleosides proved to be inactive against HIV.
Subject(s)
Anti-HIV Agents/pharmacology , Dideoxynucleosides/pharmacology , HIV-1/drug effects , HIV-2/drug effects , Prodrugs/pharmacology , Anti-HIV Agents/chemical synthesis , Anti-HIV Agents/chemistry , Dideoxynucleosides/chemical synthesis , Dideoxynucleosides/chemistry , Dose-Response Relationship, Drug , Microbial Sensitivity Tests , Molecular Structure , Prodrugs/chemical synthesis , Prodrugs/chemistry , Structure-Activity RelationshipABSTRACT
SAMHD1 is an intracellular enzyme that specifically degrades deoxynucleoside triphosphates into component nucleoside and inorganic triphosphate. In myeloid-derived dendritic cells and macrophages as well as resting T-cells, SAMHD1 blocks HIV-1 infection through this dNTP triphosphohydrolase activity by reducing the cellular dNTP pool to a level that cannot support productive reverse transcription. We now show that, in addition to this direct effect on virus replication, manipulating cellular SAMHD1 activity can significantly enhance or decrease the anti-HIV-1 efficacy of nucleotide analogue reverse transcription inhibitors presumably as a result of modulating dNTP pools that compete for recruitment by viral polymerases. Further, a variety of other nucleotide-based analogues, not normally considered antiretrovirals, such as the anti-herpes drugs Aciclovir and Ganciclovir and the anti-cancer drug Clofarabine are now revealed as potent anti-HIV-1 agents, under conditions of low dNTPs. This in turn suggests novel uses for nucleotide analogues to inhibit HIV-1 in differentiated cells low in dNTPs.
