title: Synthesis, antiproliferative and antiviral activity of imidazo[4,5-d]isothiazole nucleosides as 5:5 fused analogs of nebularine and 6-methylpurine ribonucleoside.
abstract: A series of imidazo[4,5-d]isothiazole nucleosides related to the antibiotic nebularine and the highly cytotoxic 6-methyl-9-beta-D-ribofuranosylpurine have been synthesized from the corresponding heterocycles. The sodium salt glycosylation of the imidazo[4,5-d]isothiazoles proceeded smoothly, giving mixtures of N-4 and N-6 regioisomers in generally good yields. The protected derivatives were deblocked using standard conditions to afford the desired imidazo[4,5-d]-isothiazole nucleosides, usually as crystalline solids. None of the new nucleosides or heterocycles displayed selective activity against human cytomegalovirus (HCMV) or herpes simplex virus type 1 (HSV-1). The N-6 glycosylated imidazo[4,5-d]isothiazoles were completely inactive up to the highest concentration tested. The N-6 glycosylated imidazo[4,5-d]isothiazoles also were inactive in antiproliferative and cytotoxicity assays, except for 3-methyl-6-beta-D-ribofuranosylimidazo[4,5-d]isothiazole (15a) and 5-(benzylthio)-6-(2-deoxy-beta-D-ribofuranosyl)imidazo[4,5-d]isothiaz ole (5e), which showed moderate inhibition of L1210 cell growth. However, the heterocycles and several of the N-4 glycosylated derivatives were toxic to HFF, KB and L1210 cells; compounds with 5-benzylthio substituents were the most cytotoxic agents in this series.
authors.affiliation: Department of Chemistry, College of Literature, Sciences, and the Arts, University of Michigan, Ann Arbor 48109, USA.
authors.forename: E E
authors.initials: EE
authors.lastname: Swayze
authors.forename: J C
authors.initials: JC
authors.lastname: Drach
authors.forename: L L
authors.initials: LL
authors.lastname: Wotring
authors.forename: L B
authors.initials: LB
authors.lastname: Townsend
mesh_terms: D000818:Animals; D000970:Antineoplastic Agents / Q000138:chemical synthesis* / Q000494:pharmacology; D000998:Antiviral Agents / Q000138:chemical synthesis* / Q000494:pharmacology; D002478:Cells, Cultured; D003587:Cytomegalovirus / Q000187:drug effects; D006801:Humans; D007093:Imidazoles / Q000138:chemical synthesis* / Q000494:pharmacology; D009682:Magnetic Resonance Spectroscopy; D051379:Mice; D015394:Molecular Structure; D011684:Purine Nucleosides / Q000494:pharmacology; D011687:Purines / Q000494:pharmacology; D012263:Ribonucleosides / Q000138:chemical synthesis* / Q000494:pharmacology; D018139:Simplexvirus / Q000187:drug effects; D013844:Thiazoles / Q000138:chemical synthesis* / Q000494:pharmacology; D013872:Thionucleosides / Q000138:chemical synthesis / Q000494:pharmacology*
chemical_list: D000970:Antineoplastic Agents; D000998:Antiviral Agents; D007093:Imidazoles; D011684:Purine Nucleosides; D011687:Purines; D012263:Ribonucleosides; D013844:Thiazoles; D013872:Thionucleosides; C016588:6-methylpurine; C005248:nebularine