Carbocyclic analogues of xylofuranosylpurine nucleosides. Synthesis and antitumor activity

Synthesis and biological evaluation of N 6 derivatives of 8-azapurine as novel antiplatelet agents

Two series of novel N 6 derivatives of 8-azapurine I and II were designed as antiplatelet agents. Series I and II were N 6 amino derivatives and N 6 hydrazone derivatives of 8-azapurine, respectively. The compounds were synthesized in acceptable yields via conventional procedures, including nucleophilic substitution, diazotization, and amination or hydrazonation with amino alcohol and 4,6-dichloropyrimidine as starting materials. To assess the ability of the synthesized compounds as antiplatelet agents, the ADP-induced platelet aggregation assay of Born was performed both in vitro and in vivo using ticagrelor as a reference control substance. The analysis of the structure-activity relationship and molecular docking were also discussed in detail. The results demonstrated that series I and II compounds exhibited antiplatelet activity in vitro and IIh was the most active compound (IC50 = 0.20 μM) among the target compounds, being almost 4-fold better than ticagrelor (IC50 = 0.74 μM). For a preliminary assessment of the safety profile, a bleeding test (mouse tail) and a single-dose toxicity test were conducted. The use of compound IIh resulted in a shorter bleeding time, less blood loss and lower acute toxicity compared to ticagrelor. In addition, a molecular docking study was performed to investigate the binding capacity and binding mode between IIh and P2Y12.

Xylo-C-nucleosides with a pyrrolo[2,1-f][1,2,4]triazin-4-amine heterocyclic base: Synthesis and antiproliferative properties

The synthesis of a xylo-C-nucleoside containing pyrrolo[2,1-f][1,2,4]triazin-4-amine as nucleobase along with that of its 1'-cyano analogue is described. Among different experimental conditions explored in order to optimize a key debenzylation step in the presented synthetic route, it was found that palladium catalyzed hydrogen transfer allowed for obtaining the target compounds in good yields. The resulting mixture of epimers was separated and each was characterized by NOESY NMR experiments. In vitro antiproliferative assays showed that the 1'-unsubstituted analogue was active against a panel of tumor cell lines such as the human leukemia HL-60 (IC₅₀ = 1.9 µM) and lung cancer NCI-H460 (IC₅₀ = 2.0 µM) cells.

Synthesis and evaluation of antiviral activity of higher homologues of xylo-carbocyclic nucleosides

New carbocyclic nucleosides with purine (compounds 3a and 3b), and 8-azapurine (compounds 3c and 3d) as base were prepared and assayed for in vitro activity.

Variable strategy toward carbasugars and relatives. 1. Stereocontrolled synthesis of pseudo-beta-D-gulopyranose, pseudo-beta-D-xylofuranose, (pseudo-beta-D-gulopyranosyl)amine, and (pseudo-beta-D-xylofuranosyl)amine

Four novel, chiral nonracemic carbasugars have been synthesized from 1,2-O-isopropylidene-D-glyceraldehyde. Furan- and pyrrole-based 2-silyloxy dienes--mimics of the alpha,gamma-dianions of gamma-hydroxy- and gamma-aminobutanoic acid, respectively--nicely served to complete the syntheses of two all-oxygen compounds, pseudo-beta-D-gulopyranose and pseudo-beta-D-xylofuranose, and two "anomeric" amino derivatives, (pseudo-beta-D-gulopyranosyl)amine (1,2,4-tri-epi-validamine) and (pseudo-beta-D-xylofuranosyl)amine. Two sequential, highly diastereoselective carbon-carbon bond-forming maneuvers, i.e., a vinylogous crossed aldol addition and an intramolecular aldolization, proved central to these constructions. The fact that readily available heterocyclic diene scaffolds can be employed in the assembly of a varied repertoire of carbasugars and analogues widens the prospects of dienoxy silane chemistry.

Palladium-Catalyzed Allylic Coupling of 1,2,3-Triazolo[4,5-d]pyrimidines (8-Azapurines)

The palladium-catalyzed coupling of the sodium salt of 7-amino-1,2,3-triazolo[4,5-d]pyrimidine (8-azaadenine, 1) with allylic phosphates or carbonates resulted in mixtures of 2- and 3-substituted 1,2,3-triazolopyrimidines, which were separated by chromatography. 1-Substituted triazolopyrimidines were not isolated from these reactions. Regioselectivity (and stereoselectivity) was also observed for substitution of the allylic moiety when more than one isomer is possible from the reaction. The use of 5-amino-1,2,3-triazolo[4,5-d]pyrimidin-7-ones (8-azaguanine, 2), instead of 8-azaadenine, also resulted in mixtures. Alternate syntheses of the 3-allyl-1,2,3-triazolo[4,5-d]pyrimidines confirmed the structures of these compounds.

Potent and selective activity of a new carbocyclic nucleoside analog (carbovir: NSC 614846) against human immunodeficiency virus in vitro

Carbocyclic 2',3'-didehydro-2',3'-dideoxyguanosine (Carbovir: NSC 614846), a novel nucleoside analog, emerged as a potent and selective anti-HIV agent from a large screening program conducted by the National Cancer Institute and its contractors. Its hydrolytic stability and its ability to inhibit the infectivity and replication of HIV in T-cells at concentrations of approximately 200- to 400-fold below toxic concentrations make carbovir a top-priority candidate for development as a potential antiretroviral agent in the treatment of AIDS patients.