A Bifunctional Nucleoside Probe for the Inhibition of the Human Immunodeficiency Virus-Type 1 Reverse Transcriptase

Abstract

Nucleoside analogs have proven effective for the inhibition of viral polymerases and are the foundation of many antiviral therapies. In this work, the antiretroviral potential of 6-azauracil analogs was assessed using activity-based protein profiling techniques and functional assays. Probes based on the 6-azauracil scaffold were examined and found to bind to HCV polymerase and HIV-1 reverse transcriptase through covalent modification of residues near the active site. The modified sites on the HIV-1 RT were examined using a mass spectrometry approach, and it was discovered that the azauracil moieties modified the enzyme in proximity to its active site. However, these scaffolds gave little or no inhibition of enzyme activity. Instead, a bifunctional inhibitor was prepared using click chemistry to link the 6-azauracil moiety to azidothymidine (AzT) and the corresponding triphosphate (AzTTP). These bifunctional inhibitors were found to have potent inhibitory function through a mode of action that includes both alkylation and chain termination. An in vitro assay demonstrated that the bifunctional inhibitor was 23-fold more effective in inhibiting HIV-1 RT activity than the parent AzTTP. The bifunctional inhibitor was also tested in HIV-1 permissive T cells where it decreased Gag expression similarly to the front-line drug Efavirenz with no evidence of cytotoxicity. This new bifunctional scaffold represents an interesting tool for inhibiting HIV-1 by covalently anchoring a chain-terminating nucleoside analog in the active site of the reverse transcriptase, preventing its removal and abolishing enzymatic activity, and represents a novel mode of action for inhibiting polymerases including reverse transcriptases.

Visible-Light-Induced Oxyalkylation of 1,2,4-Triazine-3,5(2H, 4H)-diones with Ethers via Oxidative Cross-Dehydrogenative Coupling

“…To further highlight the prospective application of this protocol in the synthesis of bioactive molecules, we attempted to prepare some pivotal pharmaceutical intermediates. As illustrated in Scheme , when 4-(prop-2-yn-1-yl)-1,2,4-triazine-3,5­(2 H , 4 H )-dione ( 1ar ) was chosen as a special substrate, the corresponding product 3ar was isolated in 54% yield, which could be readily transformed into Azauracil-AzT as an HIV-1 RT inhibitor through a click reaction …”

“…So, the combination of 1,2,4-triazine-3,5­(2 H , 4 H )-dione and tetrahydrofuran into candidate drug molecules is a great promising strategy to develop new medicines. In 2020, the Pezacki group demonstrated that the bifunctional inhibitor Azauracil-AzT was highly effective in inhibiting HIV-1 reverse transcriptase activity . However, the study on the medicinal properties of the 1,2,4-triazine-3,5­(2 H , 4 H )-dione and tetrahydrofuran conjugated compounds is restricted because of the scarcity of their concise and convenient preparation methods.…”

Recent Advances on the Role of Nitrogen‐Based Heterocyclic Scaffolds in Targeting HIV through Reverse Transcriptase Inhibition

“…Similar to the first‐line drug Efavirenz, the bifunctional inhibitor suppressed Gag expression in HIV‐1 permissive T cells without cytotoxicity. Compound 48 (Figure 36), which covalently binds a chain‐terminating nucleoside derivative at the active site of reverse transcriptase, preventing its removal and lowering enzymatic activity, was therefore found to be a viable option for lowering HIV‐1 [98] …”

“…Compound 48 (Figure 36), which covalently binds a chain-terminating nucleoside derivative at the active site of reverse transcriptase, preventing its removal and lowering enzymatic activity, was therefore found to be a viable option for lowering HIV-1. [98] To explore positional flexibility with HIV-1 RT, Jin and his team, synthesized a group of new diary triazines (DATAs). Among all synthesized compounds reported to be most having EC 50 = 340.9 nmol/L and EC 50 = 307 nmol/L respectively which is comparable to the standard drug, ETR in MT-4 cells.…”

Structure, Synthesis and Inhibition Mechanism of Nucleoside Analogues as HIV‐1 Reverse Transcriptase Inhibitors (NRTIs)

“…Recently, novel HIV‐1 reverse transcriptase inhibitors using zidovudine ( 1 ) have been investigated [16] . A nucleoside analogue of the azide grouped zidovudine ( 1 ) complexed with the ethynyl‐grouped azauracil by Huisgen cycloaddition displayed HIV‐1 reverse transcriptase inhibitory activity (Scheme 4).…”