Design, Synthesis, and Biological Evaluations of Hydroxypyridone­carboxylic Acids as Inhibitors of HIV Reverse Transcriptase Associated RNase H

Targeting the clinically unvalidated reverse transcriptase (RT) associated ribonuclease H (RNase H) for human immunodeficiency virus (HIV) drug discovery generally entails chemotypes capable of chelating two divalent metal ions in the RNase H active site. The hydroxypyridone­carboxylic acid scaffold has been implicated in inhibiting homologous HIV integrase (IN) and influenza endonuclease via metal chelation. We report herein the design, synthesis, and biological evaluations of a novel variant of the hydroxypyridone­carboxylic acid scaffold featuring a crucial <i>N</i>-1 benzyl or biarylmethyl moiety. Biochemical studies show that most analogues consistently inhibited HIV RT-associated RNase H in the low micromolar range in the absence of significant inhibition of RT polymerase or IN. One compound showed reasonable cell-based antiviral activity (EC₅₀ = 10 μM). Docking and crystallographic studies corroborate favorable binding to the active site of HIV RNase H, providing a basis for the design of more potent analogues

Design, Synthesis, and Biological Evaluations of Hydroxypyridone­carboxylic Acids as Inhibitors of HIV Reverse Transcriptase Associated RNase H

Targeting the clinically unvalidated reverse transcriptase (RT) associated ribonuclease H (RNase H) for human immunodeficiency virus (HIV) drug discovery generally entails chemotypes capable of chelating two divalent metal ions in the RNase H active site. The hydroxypyridone­carboxylic acid scaffold has been implicated in inhibiting homologous HIV integrase (IN) and influenza endonuclease via metal chelation. We report herein the design, synthesis, and biological evaluations of a novel variant of the hydroxypyridone­carboxylic acid scaffold featuring a crucial <i>N</i>-1 benzyl or biarylmethyl moiety. Biochemical studies show that most analogues consistently inhibited HIV RT-associated RNase H in the low micromolar range in the absence of significant inhibition of RT polymerase or IN. One compound showed reasonable cell-based antiviral activity (EC₅₀ = 10 μM). Docking and crystallographic studies corroborate favorable binding to the active site of HIV RNase H, providing a basis for the design of more potent analogues

3-Hydroxypyrimidine-2,4-diones as Selective Active Site Inhibitors of HIV Reverse Transcriptase-Associated RNase H: Design, Synthesis, and Biochemical Evaluations

Human immunodeficiency virus (HIV) reverse transcriptase (RT) associated ribonuclease H (RNase H) remains an unvalidated antiviral target. A major challenge of specifically targeting HIV RNase H arises from the general lack of selectivity over RT polymerase (pol) and integrase (IN) strand transfer (ST) inhibitions. We report herein the synthesis and biochemical evaluations of three novel 3-hydroxypyrimidine-2,4-dione (HPD) subtypes carefully designed to achieve selective RNase H inhibition. Biochemical studies showed the two subtypes with an N-1 methyl group (<b>9</b> and <b>10</b>) inhibited RNase H in low micromolar range without siginificantly inhibiting RT polymerase, whereas the N-1 unsubstituted subtype <b>11</b> inhibited RNase H in submicromolar range and RT polymerase in low micromolar range. Subtype <b>11</b> also exhibited substantially reduced inhibition in the HIV-1 INST assay and no significant cytotoxicity in the cell viability assay, suggesting that it may be amenable to further structure–activity relationship (SAR) for identifying RNase H inhibitors with antiviral activity

Design, Synthesis, Biochemical, and Antiviral Evaluations of C6 Benzyl and C6 Biarylmethyl Substituted 2‑Hydroxylisoquinoline-1,3-diones: Dual Inhibition against HIV Reverse Transcriptase-Associated RNase H and Polymerase with Antiviral Activities

Reverse transcriptase (RT) associated ribonuclease H (RNase H) remains the only virally encoded enzymatic function not targeted by current chemotherapy against human immunodeficiency virus (HIV). Although numerous chemotypes have been reported to inhibit HIV RNase H biochemically, few show significant antiviral activity against HIV. We report herein the design, synthesis, and biological evaluations of a novel variant of 2-hydroxyisoquinoline-1,3-dione (HID) scaffold featuring a crucial C-6 benzyl or biarylmethyl moiety. The synthesis involved a recently reported metal-free direct benzylation between tosylhydrazone and boronic acid, which allowed the generation of structural diversity for the hydrophobic aromatic region. Biochemical studies showed that the C-6 benzyl and biarylmethyl HID analogues, previously unknown chemotypes, consistently inhibited HIV RT-associated RNase H and polymerase with IC₅₀s in low to submicromolar range. The observed dual inhibitory activity remained uncompromised against RT mutants resistant to non-nucleoside RT inhibitors (NNRTIs), suggesting the involvement of binding site(s) other than the NNRTI binding pocket. Intriguingly, these same compounds inhibited the polymerase, but not the RNase H function of Moloney Murine Leukemia Virus (MoMLV) RT and also inhibited Escherichia coli RNase H. Additional biochemical testing revealed a substantially reduced level of inhibition against HIV integrase. Molecular docking corroborates favorable binding of these analogues to the active site of HIV RNase H. Finally, a number of these analogues also demonstrated antiviral activity at low micromolar concentrations