title: Highly selective action of triphosphate metabolite of 4'-ethynyl D4T: a novel anti-HIV compound against HIV-1 RT.
abstract: 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.
authors.affiliation: Department of Pharmacology, School of Medicine, Yale University, 333 Cedar Street, New Haven, CT 06520, USA.
authors.forename: Guangwei
authors.initials: G
authors.lastname: Yang
authors.forename: Ginger E
authors.initials: GE
authors.lastname: Dutschman
authors.forename: Chuan-Jen
authors.initials: CJ
authors.lastname: Wang
authors.forename: Hiromichi
authors.initials: H
authors.lastname: Tanaka
authors.forename: Masanori
authors.initials: M
authors.lastname: Baba
authors.forename: Karen S
authors.initials: KS
authors.lastname: Anderson
authors.forename: Yung-Chi
authors.initials: YC
authors.lastname: Cheng
mesh_terms: D000818:Animals; D019380:Anti-HIV Agents / Q000494:pharmacology*; D002417:Cattle; D004247:DNA / Q000096:biosynthesis / Q000235:genetics / Q000378:metabolism; D004259:DNA-Directed DNA Polymerase / Q000378:metabolism; D054303:HIV Reverse Transcriptase / Q000037:antagonists & inhibitors* / Q000378:metabolism; D015497:HIV-1 / Q000201:enzymology*; D006367:HeLa Cells; D006801:Humans; D019384:Nucleic Acid Synthesis Inhibitors / Q000494:pharmacology*; D011122:Polyphosphates / Q000494:pharmacology*; D012313:RNA / Q000235:genetics / Q000378:metabolism; D018894:Reverse Transcriptase Inhibitors / Q000737:chemistry / Q000494:pharmacology*; D016914:Ribonuclease H / Q000378:metabolism; D018119:Stavudine / Q000031:analogs & derivatives* / Q000737:chemistry / Q000494:pharmacology
chemical_list: D019380:Anti-HIV Agents; D019384:Nucleic Acid Synthesis Inhibitors; D011122:Polyphosphates; D018894:Reverse Transcriptase Inhibitors; D012313:RNA; C486840:2',3'-didehydro-3'-deoxy-4'-ethynylthymidine; D004247:DNA; C427203:calf thymus DNA; D018119:Stavudine; D054303:HIV Reverse Transcriptase; D004259:DNA-Directed DNA Polymerase; D016914:Ribonuclease H; C005692:triphosphoric acid