Synthesis of novel 2',3'-didehydro-2',3'-dideoxyinosine phosphoramidate prodrugs and evaluation of their anticancer activity

Synthesis and anticancer activity of 3'-[4-fluoroaryl-(1,2,3-triazol-1-yl)]-3'-deoxythymidine analogs and their phosphoramidates

A series of novel 4-chlorophenyl N-alkyl phosphoramidates of 3'-[4-fluoroaryl-(1,2,3-triazol-1-yl)]-3'-deoxythymidines (20-49) was synthesized by means of phosphorylation of 3'-[4-aryl-(1,2,3-triazol-1-yl)]-3'-deoxythymidines (7-11) with 4-chlorophenyl phosphoroditriazolide (14), followed by a reaction with the appropriate amine. The synthesized compounds 7-11 and 20-49 were evaluated along with four known anticancer compounds for their cytotoxic activity in human cancer cell lines: cervical (HeLa), nasopharyngeal (KB), breast (MCF-7), osteosarcoma (143B) (only selected compounds 20, 24, 28, 32-36, 38, 40, 46) and normal human dermal fibroblast cell line (HDF) using the sulforhodamine B (SRB) assay. Among 3'-[4-aryl-(1,2,3-triazol-1-yl)]-3'-deoxythymidines (7-11) the highest activity in all the investigated cancer cells was displayed by 3'-[4-(3-fluorophenyl)-(1,2,3-triazol-1-yl)]-3'-deoxythymidine (9) (IC₅₀ in the range of 2.58-3.61 μM) and its activity was higher than that of cytarabine. Among phosphoramidates 20-49 the highest activity was demonstrated by N-n-propyl phosphoramidate of 3'-[4-(3-fluorophenyl)-(1,2,3-triazol-1-yl)]-3'-deoxythymidine (35) in all the cancer cells (IC₅₀ in the range of 0.97-1.94 μM). Also N-ethyl phosphoramidate of 3'-[4-(3-fluorophenyl)-(1,2,3-triazol-1-yl)]-3'-deoxythymidine (33) exhibited good activity in all the used cell lines (IC₅₀ in the range of 4.79-4.96 μM).

Synthesis and anticancer activity of some 5-fluoro-2'-deoxyuridine phosphoramidates

Two series of novel 4-chlorophenyl N-alkyl phosphoramidates of 3'-O-(t-butoxycarbonyl)-5-fluoro-2'-deoxyuridine (3'-BOC-FdU) (9a-9j) and 5-fluoro-2'-deoxyuridine (FdU) (10a-10j) were synthesized by means of phosphorylation of 3'-BOC-FdU (4) with 4-chlorophenyl phosphoroditriazolide (7), followed by a reaction with the appropriate amine. Phosphoramidates 9a-9j were converted to the corresponding 10a-10j by removal of the 3'-t-butoxycarbonyl protecting group (BOC) under acidic conditions. The synthesized phosphoramidates 9a-9j and 10a-10j were evaluated for their cytotoxic activity in five human cancer cell lines: cervical (HeLa), nasopharyngeal (KB), breast (MCF-7), liver (HepG2), osteosarcoma (143B) and normal human dermal fibroblast cell line (HDF) using the sulforhodamine B (SRB) assay. Two phosphoramidates 9b and 9j with the N-ethyl and N-(methoxy-(S)-alaninyl) substituents, respectively, displayed remarkable activity in all the investigated cancer cells, and the activity was considerably higher than that of the parent nucleoside 4 and FdU. Among phosphoramidates 10a-10j compound 10c with the N-(2,2,2-trifluoroethyl) substituent showed the highest activity. Phosphoramidate 10c was more active than the FdU in all the cancer cell lines tested.