Identification of HIV-1 Reverse Transcriptase-Associated Ribonuclease H Inhibitors Based on 2-Hydroxy-1,4-naphthoquinone Mannich Bases

There is a strong demand for new and efficient antiviral compounds. A series of 2-hydroxy-1,4-naphthoquinone Mannich bases were screened for their HIV-1-RNase H inhibitory activity. An HIV-1-RNase H assay was used to study the RNase H inhibition by the test compounds. Docking of active derivatives into the active site of the enzyme was carried out. Compounds <b>1e</b> and <b>2k</b> showed distinctly higher HIV-1-RNase H inhibitory activity (IC₅₀ = 2.8-3.1 µM) than the known inhibitors RDS1759 and compound <b>13</b>. The binding mode and possible interactions of <b>1e</b> and <b>2k</b> with the HIV-1-RNase H active site were determined using molecular docking, which led to the identification of salient and concealed pharmacophoric features of these molecules. The docking analysis revealed that there are significant differences in the binding mode of these compounds within the active site of the target enzyme. A selection of HIV-1-RNase H-inhibitory Mannich bases was tested for antiviral activity against HIV-1, and compound <b>2k</b> showed the highest activity at low toxicity to host cells. The lawsone Mannich bases <b>1e</b> and <b>2k</b> also underwent a preliminary screening for activity against SARS-CoV-2, and compound <b>1e</b> was found to inhibit SARS-CoV-2 replication (IC₅₀ = 11.2 µM).