Preparation and anti-HIV activity of N-3-substituted thymidine nucleoside analogs

A series of 22 derivatives of AZT substituted at the N-3 position of the thymine base were prepared and evaluated for anti-HIV activity in cell culture (Lai strain of HIV-1 in CEM-c113 cells). The AZT analogs bearing a N-3 amino group (7), a hydroxyalkyl chain (12f), and a phosphonomethyl (12k) substituent displayed activities in the 0.045-0.082 microM range. The analogs 12d, 12e, 12q, 15, and 19 were active at <0.5 microM concentration. Compound 18 in which two molecules of AZT are connected at N-3 via a two-carbon link and "dimer" 11 also displayed significant activity. To obtain information concerning the mechanism of RT inhibition by these AZT analogs, compounds 7, 12d, 12e, and 12q were incubated with recombinant HIV-1 RT in the presence of poly(A)-oligo[dT(12-18)] and poly(C)-oligo[dG(12-18)] template-primers. In contrast to AZT-TP (control), none of these nucleosides displayed any significant inhibition of RT in the recombinant enzyme assay, indicating that phosphorylation is a necessary prerequisite for activity.