SYNTHESIS AND ANTI-HUMAN-IMMUNODEFICIENCY-VIRUS TYPE-1 ACTIVITIES OF NEW PEPTIDO-NUCLEOSIDE ANALOGS

In order to investigate whether antiproteasic peptides coupled to anti-reverse transcriptase nucleosides can act as inhibitors at the different stages of the HIV life cycle, various peptido-nucleosides were synthesized using methodologies involving (benzotriazol-1-yloxy)-tris(dimethylamino)phosphonium hexafluorophosphate (BOP) as a coupling reagent between the N-4-cytosinyl moiety and the peptide carboxy terminus. The anti-HIV-1 activity in MT(4) cells of this new class of compounds and their anti-HIV protease activities were determined. Fourteen peptido-nucleosides have been synthesized and six act against both the HIV-protease and viral replication in vitro. Although the activity of the most potent compounds against HIV was found to be one order of magnitude lower than that of the parent nucleoside drug 2',3'-dideoxy-3'-thiacytidine, this new class of compound could be of biological interest. Indeed, since the in vitro half-lives (t(1/2)) of the hydrolysis of the most potent compounds in human plasma were found to be longer than 2.5 h, these analogues could reach the infected cells in their structural integrity. This observation does not exclude that these compounds may exert their antiviral effects as combined prodrugs through extracellular or intracellular hydrolysis.