Synthesis and Antiviral Activity of Some Fluorinated Nucleotide Derivatives

Synthesis of phosphorofluoridates and phosphorofluoridothioates via the phosphoramidite approach

We present a very efficient synthetic procedure leading to the phosphorofluoridates RO-P(O)(OH)F 1 or phosphorofluoridothioates RO-P(S)(OH)F 2, which is based on the intermediary of fluorophosphoramidites (RO)P(F)N(i)Pr2 5 [R = 9-(hydroxyethyloxymethyl)guaninyl), 3'azido-3'deoxythymidinyl, thymidinyl, anhydrothymidinyl, cholesteryl, N6-benzoyl-5'-O-(4,4'-dimethoxytrityl)-2'-deoxyadenosinyl]. The activation of the amino group was performed with trimethylchlorosilane (TMCS).

S-Acyl-2-thioethyl Phosphoramidate Diester Derivatives as Mononucleotide Prodrugs

The synthesis and in vitro anti-HIV activity of phosphoramidate diester derivatives of 3'-azido-2',3'-dideoxythymidine (AZT) bearing one S-pivaloyl-2-thioethyl (tBuSATE) group and various amino residues are reported. These compounds were obtained from an H-phosphonate strategy using an amidative oxidation step. Most of these derivatives appeared to inhibit HIV-1 replication, with EC(50) values at micromolar concentration in thymidine kinase-deficient (TK-) cells, revealing a less restrictive intracellular decomposition process than previously reported for other phosphoramidate prodrugs. The proposed decomposition pathway of this new series of mixed pronucleotides may successively involve an esterase and a phosphoramidase hydrolysis.

Synthesis, anti-HIV activity, and stability studies of 5'-phosphorofluoridate derivatives of AZT

The synthesis, in vitro anti-HIV activity and stability studies of the 5'-fluorophosphate derivative of 3'-azido-3'-deoxythymidine (AZT) are reported. The results support the hypothesis that this phosphorylated entity exerts its biological effect via the delivery of the corresponding 5'-mononucleotide through an enzymatic process. However, the antiviral evaluation in thymidine kinase-deficient CEM cells as well as the stability studies in culture medium and cell extract showed that this bioconversion is not specific to the intracellular medium. Attempts to improve the biological activity of mononucleoside 5'-fluorophosphates by the use of the S-pivaloyl-2-thioethyl (tBuSATE) group as biolabile phosphate protection are reported.

New efficient synthesis of thymidine cyclic 3',5'-phosphorofluoridate and its sulfur analogue via the phosphoroamidite route

We describe the convenient synthesis of thymidine cyclic 3', 5'-phosphorofluoridate 6, which is superior to that previously reported. Our procedure is based on a sequence of reactions utilizing 3 as the key substrate. Similar sequence of reaction leads to the sulfur analogues of 6 the thymidine cyclic 3',5'-phosphorofluoridothioate 7.

Synthesis, anti-HIV activity and stability studies of 3'-azido-2',3'-dideoxythymidine 5'-fluorophosphate

The synthesis, in vitro anti-HIV activity, and stability studies of AZT 5'-fluorophosphate (F-AZTMP) are reported. The present results demonstrate that such compound is a bioprecursor of its parent 5'-mononucleotide (AZTMP) but its biotransformation does not allow its selective intracellular delivery. Moreover, several attempts were carried out in order to improve the biological activity of this compound by the use of a SATE prodrug strategy.

Molecular mechanics studies on the conformations of 2',3'-dideoxy-2',3'-didehydroguanine nucleoside, D4G

Conformational energy calculations have been presented on guanine nucleoside in which the furanose ring is replaced by 2',3'-dideoxy-2',3'-didehydrofuran using molecular mechanics and conformational analysis. Conformational energies have been evaluated using the MM2 and AMBER94 force field parameters at two different dielectric constants. The results are presented in terms of isoenergy contours in the conformational space of the glycosidic (chi) and C4'-C5' (gamma) bonds torsions. In general, the chi-gamma interrelationships differ from the corresponding plots for unmodified nucleosides and nucleotides, reported previously. Consistency of the calculated preferred conformations with the x-ray data is sensitive to the force field employed.

Modified nucleotides as substrates and inhibitors of adenylate kinase from different sources

The substrate and inhibitory properties of modified nucleotides with respect to adenylate kinase from rabbit muscles, human placenta and Escherichia coli were studied. A number of 5'-hydrogenphosphonates and 5'-fluorophosphates of modified nucleotides were shown to inhibit the phosphorylation reaction catalyzed by these enzymes. A clear difference between phosphonates of 3'-deoxyribonucleotides and the corresponding ribo- and 2',3'-dideoxyribonucleotides was found. 3'-Azido-2',3'-dideoxythymidine and its phosphorus derivatives did not inhibit the adenylate kinase reaction.