Synthesis and Biological Evaluation of 5-Fluoro-2'-deoxyuridine Phosphoramidate Analogs

Abstract

A series of alkylating phosphoramidate analogs of 5-fluoro-2'-deoxyuridine has been prepared and their growth inhibitory activity evaluated against murine L1210 leukemia and B16 melanoma cells in vitro. These compounds were designed to undergo intracellular release of the phosphoramidate anions, which it was hoped would function as irreversible inhibitors of thymidylate synthase. The expectation was that binding of the nucleoside moiety would be followed by alkylation of the enzyme via the phosphoramidate. The chloride, bromide, iodide, and tosylate analogs were highly potent inhibitors of L1210 cell proliferation, with increased inhibition observed at both higher drug concentrations and longer exposure times. Addition of thymidine completely reversed the inhibition for all compounds, suggesting that these compounds are acting via inhibition of thymidylate synthase. Although the nonalkylating morpholine analog 1f was ca. 50-fold less potent than the methyl(chloroethyl)amino compound, the piperidine analog 1g was only 2-fold less potent, confirming that nitrogen basicity may be as important as the presence of an alkylating group. Addition of thymidine reversed the growth inhibition of the morpholine and piperidine analogs, suggesting that these compounds may also undergo intracellular conversion to 5-fluoro-2'-deoxyuridine 5'monophosphate. The thymidine and deoxyuridine derivatives 2 and 3 showed minimal growth inhibition in the L1210 assay. The alkylating analogs showed modest cytotoxicity against B16 melanoma cells, and the potency of the analogs was more dependent upon the alkylating moiety than on the 5-substituent.

Pronucleotides: Toward thein vivo delivery of antiviral and anticancer nucleotides

“…121 Based on their earlier observation that perhydrooxazine derivatives of aldophosphoramides were prodrugs of phosphoramide mustard, Borch and co-workers constructed perhydrooxazine phosphoramidate diesters of FUdR and substituted ethyl amines and evaluated their anticancer activity. 121,150 Mechanistic studies revealed that the compounds decomposed rapidly in aqueous media to the corresponding phosphoramidate monoester, followed by formation of aziridinum phosphoramidate. Subsequent attack of the electrophilic aziridium phosphoramidate by water resulted in release of FUdR monophosphate.…”

“…In addition, although studies with thymidine kinase-de®cient cells were not reported, thymidine antagonism studies supported a mechanism based on FUdR monophosphate release and not direct inhibition of thymidylate synthase. 121 Studies of the in vivo antiviral or anticancer potency of phosphoramidate diesters have not been reported. As observed for the cycloSal nucleoside phosphotriesters, phosphotriester diastereomers can exhibit differences in biological potency.…”

“…Alkylating phosphoramidate diester. 121 toxicity associated with phenol released from aryl phosphoramidate monoesters is a potential issue, since the human toxicity of phenols is well-documented. 151±153…”

Isoxazolium N-ylides and 1-oxa-5-azahexa-1,3,5-trienes on the way from isoxazoles to 2H-1,3-oxazines

“…An analysis of recent literature shows that 2 H -1,3-oxazine derivatives exhibit various types of bioactivity, e.g., herbicidal [12], inhibition of cell growth and enzyme activity [13–18], inhibition of voltage-gated sodium channels [19] and metabotropic glutamate receptor-5a (hmGluR5a) [20]. Consequently, our second aim was to extend the reaction to the preparation of aryl- and halogen-substituted 1,3-oxazines, taking into account that the latter are potential candidates for metal-catalyzed couplings and thus allow further modifications.…”

Synthesis and Biological Evaluation of Butanoate, Retinoate, and Bis(2,2,2-trichloroethyl)phosphate Derivatives of 5-Fluoro-2′-deoxyuridine and 2′,5-Difluoro-2′-deoxyuridine as Potential Dual Action Anticancer Prodrugs

“…A number of strategies have been investigated to overcome the low efficacy and development of resistance to FDU. Since ionic nucleotides penetrate cells poorly and are readily dephosphorylated extracellulary, the development of lipophilic neutral masked nucleotide prodrugs that can cross the cell membrane and potentially liberate the nucleotide intracellularly has been investigated extensively [10][11][12][13][14][15] . Esters of FDU have also been widely investigated [16][17][18] .…”