title: Synthesis, anti-HIV activity, and molecular mechanism of drug resistance of L-2',3'-didehydro-2',3'-dideoxy-2'-fluoro-4'-thionucleosides.
abstract: beta-l-2',3'-Didehydro-2',3'-dideoxy-2'-fluoro-4'-thionucleosides (beta-l-2'-F-4'-S-d4Ns) have been synthesized and evaluated against HIV-1 in primary human lymphocytes. The key intermediate 8, which was prepared from 2,3-O-isopropylidene-l-glyceraldehyde 1 in 13 steps, was condensed with various pyrimidine and purine bases followed by elimination and deprotection to give the target compounds, beta-l-2'-F-4'-S-d4Ns (17-20 and 27-30). The antiviral activity of the newly synthesized compounds was evaluated against HIV-1 in human peripheral blood mononuclear (PBM) cells, among which the cytosine 17, 5-fluorocytosine 18, and adenine 27 derivatives showed potent anti-HIV activities (EC(50) = 0.12, 0.15, and 1.74 microM, respectively) without significant cytotoxicity up to 100 microM in human PBM, CEM, and Vero cells. The cytosine derivative 17 (beta-l-2'-F-4'-S-d4C), however, showed cross-resistance to a 3TC-resistant variant (HIV-1(M184V)). Molecular modeling studies suggest that the pattern of antiviral activity, similar to that of beta-l-2'-F-d4N, stemmed from their conformational and structural similarities. The isosteric substitution of sulfur for 4'-oxygen was well tolerated in the catalytic site of HIV-1 reverse transcriptase in the wild-type virus. However, the steric hindrance between the sugar moiety of the unnatural l-nucleoside and the side chains of Val184 of M184V RT in 3TC-resistant mutant HIV strains destabilizes the RT-nucleoside triphosphate complex, which causes the cross-resistance to 3TC (M184V mutant).
authors.affiliation: Department of Pharmaceutical and Biomedical Sciences, College of Pharmacy, The University of Georgia, Athens, Georgia 30602, USA.
authors.forename: Hyunah
authors.initials: H
authors.lastname: Choo
authors.forename: Youhoon
authors.initials: Y
authors.lastname: Chong
authors.forename: Yongseok
authors.initials: Y
authors.lastname: Choi
authors.forename: Judy
authors.initials: J
authors.lastname: Mathew
authors.forename: Raymond F
authors.initials: RF
authors.lastname: Schinazi
authors.forename: Chung K
authors.initials: CK
authors.lastname: Chu
mesh_terms: D000818:Animals; D019380:Anti-HIV Agents / Q000138:chemical synthesis* / Q000737:chemistry / Q000494:pharmacology; D002460:Cell Line; D002522:Chlorocebus aethiops; D024882:Drug Resistance, Viral; D054303:HIV Reverse Transcriptase / Q000737:chemistry; D015497:HIV-1 / Q000187:drug effects*; D006801:Humans; D066298:In Vitro Techniques; D007963:Leukocytes, Mononuclear / Q000187:drug effects / Q000821:virology; D008958:Models, Molecular; D009705:Nucleosides / Q000138:chemical synthesis* / Q000737:chemistry / Q000494:pharmacology; D013329:Structure-Activity Relationship
chemical_list: D019380:Anti-HIV Agents; D009705:Nucleosides; D054303:HIV Reverse Transcriptase