title: Enantioselective synthesis and biological evaluation of 5-o-carboranyl pyrimidine nucleosides.
abstract: Base-modified carborane-containing nucleosides such as 5-o-carboranyl-2'-deoxyuridine (CDU) when combined with neutrons have potential for the treatment of certain malignancies. Lack of toxicity in various cells, high accumulation in cancer cells and intracellular phosphorylation are desirable characteristics for modified nucleosides used in boron neutron capture therapy (BNCT) for brain tumors and other malignancies. The aim of this work was to synthesize the two beta-enantiomers of several 5-o-carboranyl-containing nucleosides. These derivatives may possess favorable properties such as high lipophilicity, high transportability, the ability to be phosphorylated, and resistance to catabolism. Beta-isomers of 2',3'-dihydroxynucleosides and analogues containing a heteroatom in the sugar moiety were also synthesized. Carboranyl pyrimidine nucleosides were prepared either from the parent beta-D-nucleoside, beta-L-nucleoside, or by a coupling reaction. The dioxolane derivative 7 was prepared by a coupling reaction between protected 5-o-carboranyluracil (8, CU) and the corresponding protected heterocycle. Specific catalysts were used during the N-glycosylation process to favor the formation of the beta-isomer. Biological evaluation of these new chiral 5-o-carboranyl pyrimidine derivatives indicated that most of these compounds have low toxicity in a variety of normal and malignant cells and achieved high cellular levels in a lymphoblastoid cell line. Increasing the number of hydroxyl groups on the sugar moiety decreased the cellular accumulation and serum binding to different extents. Five compounds were identified for further biological evaluation as potential agents for BNCT.
authors.affiliation: Department of Pediatrics, Emory University School of Medicine, Atlanta, GA 30322, USA.
authors.forename: N S
authors.initials: NS
authors.lastname: Mourier
authors.forename: A
authors.initials: A
authors.lastname: Eleuteri
authors.forename: S J
authors.initials: SJ
authors.lastname: Hurwitz
authors.forename: P M
authors.initials: PM
authors.lastname: Tharnish
authors.forename: R F
authors.initials: RF
authors.lastname: Schinazi
mesh_terms: D000818:Animals; D019380:Anti-HIV Agents / Q000138:chemical synthesis / Q000737:chemistry / Q000494:pharmacology; D000970:Antineoplastic Agents / Q000138:chemical synthesis* / Q000737:chemistry / Q000494:pharmacology*; D001896:Boron Compounds / Q000138:chemical synthesis* / Q000737:chemistry / Q000494:pharmacology*; D016754:Boron Neutron Capture Therapy; D004354:Drug Screening Assays, Antitumor; D006801:Humans; D066298:In Vitro Techniques; D009682:Magnetic Resonance Spectroscopy; D011742:Pyrimidine Nucleotides / Q000138:chemical synthesis* / Q000737:chemistry / Q000494:pharmacology*; D051381:Rats; D013237:Stereoisomerism; D014407:Tumor Cells, Cultured
chemical_list: D019380:Anti-HIV Agents; D000970:Antineoplastic Agents; D001896:Boron Compounds; D011742:Pyrimidine Nucleotides