Guanine α-carboxy nucleoside phosphonate (G-α-CNP) shows a different inhibitory kinetic profile against the DNA polymerases of human immunodeficiency virus (HIV) and herpes viruses (original) (raw)
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Organic & Biomolecular Chemistry, 2010
A polymer-bound α, β-methylene-β-triphosphitylating reagent was synthesized and subjected to reactions with unprotected nucleosides, followed by oxidation, deprotection of cyanoethoxy groups, and acidic cleavage to afford nucleoside 5′-O-α, β-methylene-β-triphosphates. Among all the compounds, cytidine 5′-O-α, β-methylene-β-triphosphate inhibited RNase H activity of HIV-1 reverse transcriptase with a K i value of 225 μM. Modified nucleoside triphosphates have received much attention as mimics of naturally occurring deoxyribo-and ribonucleoside triphosphates, as probes in several biochemical pathways involving DNA and RNA synthesis, and as potential diagnostic and therapeutic agents. 1,2 The structural similarity of modified nucleotides to natural nucleoside triphosphates make them useful reagents as substrates or inhibitors for DNA or RNA polymerases. 3,4 Although most natural polymerase enzymes incorporate natural nucleoside triphosphates into nucleic acids, there are certain polymerases that are capable of incorporating unnatural nucleoside triphosphates into nucleic acids. 5-7 A number of approaches have been focused on modifications and/or substitution on the base, 8-9 carbohydrate, 10-13 and linear triphosphate moieties 14-17 to design modified nucleotides for diverse applications in nucleic acid and antiviral research. Early in the life cycle of human immunodeficiency virus type 1 (HIV-1), viral RNA is reverse transcribed into double stranded DNA for integration into the genome of the infected cell. 18 This process is catalyzed by reverse transcriptase (RT), a virus encoded heterodimeric enzyme composed of 66 and 51 kD subunits (p66 and p51), possessing DNA polymerase and ribonuclease H (RNase H) activities. 19 DNA polymerase activity is required for the synthesis of RNA: DNA heteroduplex from the single stranded viral RNA. Whereas, RNase H activity † Electronic supplementary information (ESI) available: Experimental procedures, characterization of resins with IR and final compounds with NMR, high-resolution mass spectrometry, and quantitative phosphorus analysis, DNA polymerase assay results.
Biochemistry, 2008
Employing a novel strategy, we have virtually screened a large library of compounds to identify novel inhibitors of the reverse transcriptase (RT) of HIV-1. Fifty-six top scored compounds were tested in vitro, and two of them inhibited efficiently the DNA polymerase activity of RT. The most effective compound, N-{2-[4-(aminosulfonyl)phenyl]ethyl}-2-(2-thienyl)acetamide (NAPETA), inhibited both RNAdependent and DNA-dependent DNA polymerase activities, with apparent IC 50 values of 1.2 and 2.1 µM, respectively. This inhibition was specific to the RT-associated polymerase activity and did not affect the RNase H activity. NAPETA also inhibited two drug-resistant HIV-1 RT mutants as well as HIV-2 RT and other DNA polymerases. Kinetic analysis of RT inhibition indicated that the DNA polymerase activity of HIV-1 RT was inhibited in a classic noncompetitive manner with respect to dTTP, demonstrating a K i value of 1.2 µM. In contrast, the inhibition with respect to the RNA‚DNA template was a mixed linear type with a K i value of 0.12 µM and was not affected by the order in which the template‚primer and inhibitor were added to the reaction mixture. Gel shift and surface plasmon resonance analyses confirmed that NAPETA interfered with the formation of the RT‚DNA complex (that is crucial for the polymerization activity) by reducing the affinity of RT for DNA, accounting at least partially for the inhibition. It is likely that NAPETA inhibited RT via a mechanism that is different from that of the classic non-nucleoside RT inhibitors used for treating AIDS/HIV patients and, thus, may serve as a lead compound for the development of novel anti-HIV drugs. The reverse transcriptase (RT) 1 of human immunodeficiency virus type-1 (HIV-1) is an essential enzyme in the life cycle of this retrovirus. Upon infecting the target cell, RT copies the viral plus sense and single-stranded genomic RNA into a double-stranded DNA. This complex reverse transcription process, which is common in all retroviruses, is catalyzed solely by RT and is mediated by the three activities of the enzyme. The two related RNA-dependent DNA polymerase (RDDP) and DNA-dependent DNA polymerase (DDDP) activities enable DNA synthesis of the viral genome, whereas the ribonuclease H (RNase H) activity concomitantly cleaves the viral RNA strand in the RNA‚ DNA heteroduplex. The resulting double-stranded DNA is transported into the infected cell nucleus, as part of a preintegration complex, and is subsequently incorporated into the cellular DNA by the viral integrase (1). Almost all inhibitors of HIV-1 RT can be grouped into two classes of potent compounds: nucleoside/nucleotide RT inhibitors (NRTIs) and non-nucleoside RT inhibitors (NNR-TIs) (2). NRTIs are competitive inhibitors that are phosphorylated by cellular kinases and subsequently mimic normal nucleotides. Since NRTIs lack the 3′-OH group, their incorporation into the nascent DNA by RT blocks further addition of nucleotides and, hence, leads to termination of chain elongation. The NNRTIs are a variety of hydrophobic noncompetitive inhibitors that are presumed to bind specifically to a hydrophobic pocket located in the proximity of the DNA polymerase active site of the RT (3). Most NNRTIs are highly specific against HIV-1 RT with minimal effects on the closely related HIV-2 RT (4). Both classes of inhibitors are currently used in the therapy against HIV-1
Moscow University Chemistry Bulletin, 2008
Two types of novel nucleoside analogs have been synthesized: acyclic (Z)-and (E)-isomers of 9-[3-(phosphonometoxy)prop-1-en-1-yl]adenine and a carbocyclic isosteric analog of guanosine monophosphate. The (Z)-and (E)-isomers inhibit the replication of herpes simplex virus (HSV) and human immunodeficiency virus (HIV) and are nontoxic for cells. The (Z)-isomer activities against both viruses are higher than the (E)-isomer activities. Diphosphates of these compounds display substrate activities towards recombinant HSV DNA polymerase and HIV reverse transcriptase (RT). Diphosphate of the carbocyclic guanosine analog has no substrate activity towards HSV DNA polymerase but is active as a RT substrate.
Antimicrobial Agents and Chemotherapy, 2011
To investigate the mechanism of the antiviral activity, the active metabolites of HPMPC and HPMPA were studied for their effects on reactions catalyzed by HIV-1 RT. Incorporation of HPMPC and HPMPA into a DNA primer strand resulted in multiple inhibitory effects exerted on the enzyme and showed that neither compound acts as an absolute chain terminator. Further, inhibition of HIV-1 RT also occurred when these drugs were located in the template strand. These results indicate that HPMPC and HPMPA inhibit HIV-1 by a complex mechanism and suggest that this class of drugs has a broader spectrum of activity than previously shown.
Design, Synthesis, and Antiviral Evaluation of Chimeric Inhibitors of HIV Reverse Transcriptase
ACS Medicinal Chemistry Letters, 2013
In a continuing study of potent bifunctional anti-HIV agents, we rationally designed a novel chimeric inhibitor utilizing thymidine (THY) and a TMC derivative (a diarylpyrimidine NNRTI) linked via a polymethylene linker (ALK). The nucleoside, 5-hydrogen-phosphonate (H-phosphonate) and 5-triphosphate forms of this chimeric inhibitor (THY-ALK-TMC) were synthesized and the antiviral activity profiles were evaluated at the enzyme and cellular level. The nucleoside triphosphate (11) and the Hphosphonate (10) derivatives inhibited RT polymerization with an IC 50 value of 6.0 nM and 4.3 nM, respectively. Additionally, chimeric nucleoside (9) and H-phosphonate (10) derivatives reduced HIV replication in a cell-based assay with low nanomolar antiviral potencies.
Antiviral Chemistry and Chemotherapy
Background The replacement of β,γ-pyrophosphate by β,γ-phosphonate moieties within the triphosphate chain of 5′-triphosphate nucleoside analogues was previously studied for various antiviral nucleoside analogues such as AZT and 2′,3′-dideoxynucleosides. Thus, it has been shown that these chemical modifications could preserve, in some cases, the terminating substrate properties of the triphosphate analogue for HIV-RT. Herein, we aimed to study such 5′-triphosphate mimics based on the scaffold of the well-known antiviral agent 9-[(2-phosphonomethoxy)ethyl]adenine (PMEA, Adefovir). Methods Synthesis involved coupling of a morpholidate derivative of PMEA with appropriate pyrophosphoryl analogues. The relative efficiencies of incorporation of the studied diphosphate phosphonates were measured using subtype B WT HIV-1 RT in an in vitro susceptibility assay, in comparison to the parent nucleotide analogue (PMEApp). Results Searching for nucleoside 5′-triphosphate mimics, we have synthesize...
Journal of Medicinal Chemistry, 2005
The triphosphates of antiviral 2′,3′-dideoxynucleosides (ddNs) are the active chemical species that inhibit viral DNA synthesis. The inhibition involves incorporation of ddNMP into DNA and subsequent chain termination. A conceivable strategy for antiviral drugs is to employ nucleoside 5′-triphosphate mimics that can entirely bypass cellular phosphorylation. AZT 5′-R-R P-borano-,γ-(difluoromethylene)triphosphate (5′-RB-γCF 2 TP) has been identified as a potent inhibitor of HIV-1 reverse transcriptase (HIV-1 RT). This work was aimed at confirming that 5′-RB-γCF 2 TP is a useful generic triphosphate moiety and can render antiviral ddNs with potent inhibitory effects on HIV-1 RT. Thus, 10 ddNs were converted to their 5′-RB-γCF 2-TPs via a sequence (one-pot) of reactions: formation of an activated phosphite, formation of a cyclic triphosphate, boronation, and hydrolysis. Other synthetic routes were also explored. All ddN 5′-RB-γCF 2 TPs tested exhibited essentially the same level of inhibition of HIV-1 RT as the corresponding ddNTPs. A conclusion can be made that 5′-RB-γCF 2 TP is a generic and promising triphosphate mimic (P3M) concerning HIV-1 RT inhibition and serum stability. It is anticipated that use of 5′-RB-γCF 2 TP as P3M moiety will lead to the discovery of a new class of anti-HIV agents.