Activities of 3'-azido-3'-deoxythymidine nucleotide dimers in primary lymphocytes infected with human immunodeficiency virus type 1

Abstract

The relative antiviral potencies of five nucleotide heterodimers of 3'-azido-3'-deoxythymidine (AZT), 3'-azido-3'-deoxythymidilyl-(5',5')-2'-3'-dideoxy-5'-adenylic acid (AZT-P-ddA), 3'-azido-3'-deoxythymidilyl-(5',5')-2',3'-dideoxy-5'-inosinic acid (AZT-P-ddI), and the corresponding 2-cyanoethyl congeners AZT-P(CyE)-ddA and AZT-P(CyE)-ddI, were determined in primary human peripheral blood mononuclear cells infected with human immunodeficiency virus type 1. The homodimer 3'-azido-3'-deoxythymidilyl-(5',5')-3'-azido-3'-deoxythymidilic acid (AZT-P-AZT) was also included for comparison. The potencies of the compounds were AZT-P-ddA greater than or equal to AZT-P-ddI greater than AZT-P(CyE)-ddA greater than or equal to AZT-P(CyE)-ddI greater than or equal to AZT greater than AZT-P-AZT. Whereas AZT-P-ddA and AZT-P-ddI had in vitro therapeutic indices greater than that of AZT, the homodimer of AZT had a low therapeutic index. AZT-P-ddI exhibited the lowest toxicity in peripheral blood mononuclear, Vero, or CEM cells. Combination studies between AZT and 2',3'-dideoxyinosine (ddI) at nontoxic concentrations indicated a synergistic interaction at a drug ratio of 1:100. At higher ratios (1:500 and 1:1,000), the interactions were synergistic only at concentrations that produced up to 75% virus inhibition. At higher levels of antiviral effects, this combination was antagonistic, as determined by the multiple drug effect analysis method. AZT-P-ddI was about 10-fold less toxic than AZT to human granulocyte-macrophage progenitor cells. However, no significant difference was apparent when the compounds were evaluated against cells of the erythroid lineage. The greater antiviral activity and lower toxicity of this compound could not be attributed to the extracellular decomposition of the dimer in media at physiological temperature and pH. However, in acidic solutions, AZT-P-ddI decomposed in a pH-dependent manner. Advanced preclinical studies with this heterodimer of two clinically effective antiretroviral agents should be considered.

Synthesis and Evaluation of 2,6-Modified Purine 2′-C-Methyl Ribonucleosides as Inhibitors of HCV Replication

“…Therefore, in order to overcome the often rate-limiting first phosphorylation step and improve the antiviral activity of our nucleoside analogues, we prepared their corresponding monophosphate McGuigantype prodrugs. 12 The synthesis of phosphoramidates 31−46 was performed following the Uchiyama procedure by reacting the nucleosides 10−12, 14,15,17,18,20,22,23,25,26,28, and 29 with chlorophosphoramidate 30 13 in the presence of N-methylimidazole (Scheme 4). 14,15 It is noteworthy that the use of acetonitrile as a cosolvent improved the solubility of certain nucleosides leading to better overall yields.…”

“…17 In addition cytotoxicity was determined in primary human peripheral blood mononuclear (PBM) cells, human lymphoblastoid CEM, and African Green monkey Vero cells (Table 1). 18,19 In an initial set of compounds, unusual 6-modifications such as introduction of a phosphonate ester or an ethoxy vinyl group were counterproductive and lead to inactive nucleosides and monophosphate prodrugs 14, 15, 34, and 35. Similarly, purine derivatives 25 (2,6-diMeO), 22 (2-OH, 6-NH 2 ), 23 (2-OH, 6-MeO), and 29 (2-NHOMe, 6-NH 2 ) and their corresponding phosphoramidate prodrugs 39, 41, 46, and 42 showed to be inactive against HCV up to 10 μM.…”

Antiviral β-L-nucleosides specific for hepatitis B virus infection

“…Anti-HIV-1 activity of the compounds was determined in human peripheral blood mononuclear (PBM) cells as previously described (41). Cells were infected with HIV-1 LAI at a multiplicity of infection of 0.01.…”

“…Virus obtained from cell culture supernatant was quantitated on day 6 after infection using a reverse transcriptase assay and (rA) n ⅐ (dT) [12][13][14][15][16][17][18] as a template primer. The toxicity of the compounds was assessed in human PBM cells as previously described (41). The antiviral 50% effective concentration (EC 50 ) and 50% cytotoxic concentration were determined from the concentration-response curve using the median effect method (1).…”

Synthesis, and Some Properties of, Amphiphilic Dinucleoside Phosphate Derivatives of 3′-azido-2′,3′-dideoxythymidine (AZT)

“…Dinucleoside phosphates have been prepared in which AZT is bound covalently via a phosphodiester linkage to another anti-HIV active nucleoside analogue. These molecules can be cleaved intracellularly by phosphodiesterases into a nucleotide and a nucleoside, whereby both AZT-5'-monophosphate and AZT can be formed (Busso et al, 1988;Schinazi et al, 1990). For all these compounds, the masking of AZT-5'-monophosphate can only be successful if these prodrugs are taken up by cells before AZT-5'-monophosphate is released.…”