Development of Triazoles and Triazolium Salts Based on AZT and Their Anti-Viral Activity against HIV-1

Abstract

We report herein a set of 3'-azido-3'-deoxythymidine (AZT) derivatives based on triazoles and triazolium salts for HIV-1 infection. The compounds were synthesized via click chemistry with Cu(I) and Ru(II) catalysts. Triazolium salts were synthesized by reaction with methyl iodide or methyl triflate in good yields. The antiviral activity of the compounds was tested using two methodologies: In method one the activity was measured on infected cells; in method two a pre-exposure prophylaxis experimental model was employed. For method one the activity of the compounds was moderate, and in general the triazolium salts showed a decreased activity in relation to their triazole precursors. With method two the antiviral activity was higher. All compounds were able to decrease the infection, with two compounds able to clear almost all the infection, while a lower antiviral activity was noted for the triazolium salts. These results suggest that these drugs could play an important role in the development of pre-exposure prophylaxis therapies.

Keywords: AZT; HIV-1; anti-viral; click chemistry; triazoles; triazolium salts.

Scheme 1

Modification of AZT via click chemistry with copper(I) and ruthenium(II) catalysts.

Figure 1

Representative 1,4- and 1,5-triazoles synthesized in this work, compounds 1–7.

Figure 2

Representative methyl triazolium salts 8–11.

Scheme 2

Schematic representation of methodological approach. Human peripheral blood cells were isolated from whole blood through gradient centrifugation [28,29,31]. Primary CD4⁺ T cells were infected with a GFP-tagged HIV-1 NL4.3 virus for 5 days [30]. In method 1, cells were infected with HIV-1 and then treated with AZT-derivatives. In method 2, primary T cells were pre-treated with AZT-derivatives for 18 h, then washed to remove the drugs and allow for HIV-1 infection. To restore drug treatment, 10 µM of AZT-derivative was added post-infection. At the end of the 5 days, HIV-1 replication was assessed by comparing the frequency of HIV-1 infected cells in non-treated versus AZT-derivative treated conditions by flow cytometry.

Figure 3

Flow cytometry gating strategy to assess the frequency of HIV-1 infected primary CD4⁺ T cells. To determine the frequency of HIV-1 infection in primary CD4⁺ T cells, peripheral mononuclear cells were sequentially gated on lymphocyte (left plot), live cells gate (middle plot), and HIV-1⁺ gate.

Figure 4

Frequency of HIV-1 infected primary CD4⁺ T cells treated with AZT-derivatives post-infection. Dot plots illustrating primary T cells HIV-1 infection levels in primary CD4⁺ T cells either left untreated (infected) or treated post-infection with AZT-derivatives (Infected+ compound).

Figure 5

Frequency of HIV-1 infected primary CD4⁺ T cells treated with AZT-derivatives before infection. Dot plots illustrating primary T cells HIV-1 infection levels in primary CD4⁺ T cells either left untreated (infected) or treated post with AZT-derivatives (Infected+ compound).

Figure 6

AZT-derivatives exhibit pre-exposure prophylaxis potential. Plotted fold-change in the frequency of HIV-1 infected CD4⁺ T cells upon treatment with different AZT-derivatives.

Figure 7

Frequency of HIV-1 infected primary CD4⁺ T cells treated with AZT-derivatives before infection. Dot plots illustrating primary T cells HIV-1 infection levels in primary CD4⁺ T cells either left untreated (infected) or treated post with AZT-derivatives (Infected + compound).