Highly selective action of triphosphate metabolite of 4'-ethynyl D4T: a novel anti-HIV compound against HIV-1 RT

Antiviral Res. 2007 Mar;73(3):185-91. doi: 10.1016/j.antiviral.2006.10.002. Epub 2006 Nov 10.


2',3'-Didehydro-3'-deoxy-4'-ethynylthymidine (4'-Ed4T), is a recently discovered nucleoside reverse transcriptase inhibitor (NRTI) showing a 5- to 10-fold greater anti-human immunodeficiency virus type 1 (HIV-1) activity and less cellular and mitochondrial toxicity than its parental compound, stavudine (D4T). It is also active against a variety of NRTI-resistant HIV-1 mutants under non-cytotoxic concentrations. In this study, the effects of 4'-Ed4TTP, which is the triphosphate metabolite of 4'-Ed4T, on HIV-1 reverse transcriptase (RT) activity were investigated. We found that 4'-Ed4TTP was a substrate of HIV-1 RT serving as a DNA chain terminator, and it inhibited the DNA polymerase activity of RT more efficiently than D4TTP. The value of Ki(4'-Ed4TTP)/Km(dTTP) is 0.15 for DNA/RNA primer/template duplex (P/T), but 0.7 for DNA/DNA P/T, suggesting 4'-Ed4TTP inhibits RT more efficiently during RNA-dependent DNA synthesis than DNA-dependent DNA synthesis. 4'-Ed4TTP was also found to inhibit the 3TC (Lamivudine)-resistant RT mutant, M184V, with 3-fold less efficiency than the wild type (wt) RT. 4'-Ed4TTP showed much less inhibitory effects toward major host DNA polymerases. Overall, our results suggest that 4'-Ed4TTP is the active form for anti-HIV-1 activity via its inhibitory effect against RT.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Anti-HIV Agents / pharmacology*
  • Cattle
  • DNA / biosynthesis
  • DNA / genetics
  • DNA / metabolism
  • DNA-Directed DNA Polymerase / metabolism
  • HIV Reverse Transcriptase / antagonists & inhibitors*
  • HIV Reverse Transcriptase / metabolism
  • HIV-1 / enzymology*
  • HeLa Cells
  • Humans
  • Nucleic Acid Synthesis Inhibitors / pharmacology*
  • Polyphosphates / pharmacology*
  • RNA / genetics
  • RNA / metabolism
  • Reverse Transcriptase Inhibitors / chemistry
  • Reverse Transcriptase Inhibitors / pharmacology*
  • Ribonuclease H / metabolism
  • Stavudine / analogs & derivatives*
  • Stavudine / chemistry
  • Stavudine / pharmacology


  • Anti-HIV Agents
  • Nucleic Acid Synthesis Inhibitors
  • Polyphosphates
  • Reverse Transcriptase Inhibitors
  • RNA
  • 2',3'-didehydro-3'-deoxy-4'-ethynylthymidine
  • DNA
  • calf thymus DNA
  • Stavudine
  • HIV Reverse Transcriptase
  • DNA-Directed DNA Polymerase
  • Ribonuclease H
  • triphosphoric acid