title: Stereoselective synthesis and antiviral activity of D-2',3'-didehydro-2',3'-dideoxy-2'-fluoro-4'-thionucleosides.
abstract: As 2',3'-didehydro-2',3'-dideoxy-2'-fluoronucleosides have exhibited interesting antiviral effects against HIV-1 as well as HBV, it is of interest to synthesize the isosterically substituted 4'-thionucleosides in which 4'-oxygen is replaced by a sulfur atom. To study structure-activity relationships, various pyrimidine and purine nucleosides were synthesized from the key intermediate (2R,4S)-1-O-acetyl-5-O-(tert-butyldiphenylsilyl)-2,3-dideoxy-2-fluoro-2-phenylselenyl-4-thio-beta-D-ribofuranoside 8, which was prepared from the 2,3-O-isopropylidene-D-glyceraldehyde 1 in 13 steps. The antiviral activity of the synthesized compounds were evaluated against HIV-1 in human peripheral blood mononuclear (PBM) cells, among which cytidine 17, 5-fluorocytidine 18, adenosine 24, and 2-fluoroadenosine 32 showed moderate to potent anti-HIV activities (EC(50) 1.3, 11.6, 8.1, and 1.2 microM, respectively). It is noteworthy that 2-fluoroadenosine analogue 32 showed antiviral potency as well as high cytotoxicity (IC(50) 1.5, 1.1, and 7.6 microM for PBM, CEM, and Vero, respectively) whereas no other compound showed cytotoxicity up to 100 microM. The cytidine 17 and 5-fluorocytidine 18 analogues showed significantly decreased antiviral activity against the clinically important lamivudine-resistant variants (HIV-1(M184V)), whereas the corresponding D-2'-Fd4 nucleosides showed limited cross-resistance. Molecular modeling studies demonstrated that the larger van der Waals radius as well as the close proximity to Met184 of the 4'-sulfur atom of D-2'-F-4'-Sd4C (17) may be the reasons for the decreased antiviral potency of synthesized 4'-thio nucleosides against the lamivudine-resistant variants (HIV-1(M184V)).
authors.affiliation: Department of Pharmaceutical and Biomedical Sciences, College of Pharmacy, The University of Georgia, Athens, Georgia 30602, USA.
authors.forename: Youhoon
authors.initials: Y
authors.lastname: Chong
authors.forename: Hyunah
authors.initials: H
authors.lastname: Choo
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; D000998:Antiviral Agents / Q000138:chemical synthesis* / Q000737:chemistry / Q000494:pharmacology; D001665:Binding Sites; D002460:Cell Line; D002522:Chlorocebus aethiops; D024882:Drug Resistance, Viral; D054303:HIV Reverse Transcriptase / Q000737:chemistry / Q000235:genetics; D015497:HIV-1 / Q000187:drug effects; D006801:Humans; D019259:Lamivudine / Q000494:pharmacology; D007963:Leukocytes, Mononuclear / Q000187:drug effects / Q000821:virology; D008958:Models, Molecular; D009154:Mutation; D011684:Purine Nucleosides / Q000138:chemical synthesis* / Q000737:chemistry / Q000494:pharmacology; D011741:Pyrimidine Nucleosides / Q000138:chemical synthesis* / Q000737:chemistry / Q000494:pharmacology; D011789:Quantum Theory; D013237:Stereoisomerism; D016047:Zalcitabine / Q000031:analogs & derivatives / Q000138:chemical synthesis* / Q000737:chemistry / Q000494:pharmacology
chemical_list: C467715:1-(2,3-dideoxy-2,3-didehydro-2-fluoro-4-thioribofuranosyl)cytosine; D019380:Anti-HIV Agents; D000998:Antiviral Agents; D011684:Purine Nucleosides; D011741:Pyrimidine Nucleosides; D019259:Lamivudine; D016047:Zalcitabine; D054303:HIV Reverse Transcriptase