Preparation and antileukemic screening of some new 6'-deoxyhexopyranosyladenine nucleosides

Facile synthesis of 1',2'-cis-beta-pyranosyladenine nucleosides

1',2'-cis-beta-Glycosyladenine nucleosides, such as beta-altroside, beta-mannoside, and beta-idoside, were efficiently synthesized from the corresponding 1',2'-trans-beta-6-chloropurine derivatives, beta-glucoside, and beta-galactoside. Nucleophilic substitution of the O-trifluoromethanesulfonyl groups at the C-2' and/or 3' was carried out using tetrabutylammonium acetate or cesium acetate under mild conditions. Subsequent deprotection and amidation afforded the desired compounds, 1',2'-cis-beta-pyranosyladenine nucleosides.

Enzymatic formation of potential anticancer and antiviral inosine analogues

Theoretically, inosine analogues should act as effective inhibitors of tumor cell proliferation and viral replication. To acquire a broad spectrum of new candidate inosine analogues, a rapid, facile, quantitative and stereoselective method for deaminating potential antitumor and antiviral adenine analogues previously synthesized in our laboratory was developed. A novel 5'-adenylic acid deaminase, with relaxed substrate requirements, from Aspergillus species was utilized to deaminate four hexofuranosyladenine nucleosides and five adenine nucleoside dialdehydes to their corresponding inosine analogues. The fastest rates of deamination for the hexofuranosyl nucleosides were for the compounds where the vicinal hydroxyl groups on the sugars are oriented in the erythro configuration. For rapid deamination of the adenine nucleoside dialdehydes, the R configuration at the proximal carbon atom is preferred, while the nature of the group on the distal carbon atom has no significant effect on the rate or extent of deamination.

Synthesis and antileukemic activity of certain D-fucopyranosyl nucleosides

Based upon previously discovered antileukemic properties of 9-beta-D-fucopyranosyladenine (1) in cell culture, four new nucleosides containing naturally occurring bases have been prepared from D-fucose. alpha-D-Fucopyranose tetraacetate was condensed with the silylated bases in either acetonitrile or 1,2-dichloroethane with tin(IV) chloride as the catalyst. The intermediate blocked nucleosides were obtained in crystalline form and deacetylated with methanolic sodium methoxide. 1-beta-D-Fucopyranosyluracil (8), 1-beta-D-fucopyranosylthymine (9), 1-beta-D-fucopyranosylcytosine (10) as the hydrochloride salt, and 7-beta-D-fucopyranosylguanine (11) were crystallized, and their structures were verified by spectroscopic techniques. Nucleosides 8 and 9 had only borderline activity against leukemia L1210 cells grown in culture, whereas nucleoside 11 had activity equal to 1. However, nucleoside 10 proved to be twice as active as either 1 or 11. The antileukemic activity, which was due to the inhibition of cell division, was reversible by transfer of the arrested cells to fresh media or by the addition of cytidine.

Antiproliferative activity of purine nucleoside dialdehydes against leukemia L1210 in vitro

Sixteen purine nucleoside dialdehydes were assayed for antiproliferative activity against murine leukemia L1210 grown in vitro. These compounds either lacked the terminal hydroxymethyl group that is necessary in most cases for phosphorylation, and/or had stereochemically different configurations at one or two positions, or had some alteration in the purine ring structure. Among the latter were two lipophilic N6-benzyladenine containing dialdehydes, and two nucleoside dialdehydes with a bromine atom at C-8 of the purine. These nucleoside dialdehydes, unlike most clinically useful anticancer nucleosides, did not require enzymatic phosphorylation to become activated. The most interesting agent in this group of compounds was the lipophilic nucleoside dialdehyde obtained from N6-benzyladenosine after periodate oxidation. It had an IC50 of 1.0 +/- 0.2 microM, and appears to function by limiting the formation of deoxyguanosine diphosphate (dGDP) by inhibition of ribonucleoside diphosphate reductase, the rate limiting step in the biosynthesis of deoxyribonucleotides.

Antiproliferative effects of 4',5'-unsaturated adenine nucleosides on leukemia L1210 cells in vitro

Several 4',5'-unsaturated adenine nucleosides were shown to have antiproliferative activity against L1210 leukemia cells in vitro. The active nucleosides were cytotoxic to the L1210 cells as demonstrated by Trypan Blue uptake. The cytotoxicity was not induced by alterations in the ribonucleoside and deoxyribonucleoside triphosphate levels of the L1210 cells.