2-hydroxy-4h-isoquinoline-1-3-dione and HIV-Infections

Human immunodeficiency virus (HIV) reverse transcriptase (RT) associated ribonuclease H (RNase H) remains the only virally encoded enzymatic function not clinically validated as an antiviral target. 2-Hydroxyisoquinoline-1,3-dione (HID) is known to confer active site directed inhibition of divalent metal-dependent enzymatic functions, such as HIV RNase H, integrase (IN) and hepatitis C virus (HCV) NS5B polymerase. We report herein the synthesis and biochemical evaluation of a few C-5, C-6 or C-7 substituted HID subtypes as HIV RNase H inhibitors. Our data indicate that while some of these subtypes inhibited both the RNase H and polymerase (pol) functions of RT, potent and selective RNase H inhibition was achieved with subtypes 8-9 as exemplified with compounds 8c and 9c.

Topics: Anti-HIV Agents; Catalytic Domain; Drug Design; HIV Infections; HIV Reverse Transcriptase; HIV-1; Humans; Isoquinolines; Molecular Docking Simulation; Reverse Transcriptase Inhibitors; Ribonuclease H

Clinical HIV-1 integrase (IN) strand transfer inhibitors (INSTIs) potently inhibit viral replication with a dramatic drop in viral load. However, the emergence of resistance to these drugs underscores the need to develop next-generation IN catalytic site inhibitors with improved resistance profiles. Here, we present a novel candidate IN inhibitor, MB-76, a 2-hydroxyisoquinoline-1,3(2H,4H)-dione (HID) derivative. MB-76 potently blocks HIV integration and is active against a panel of wild-type as well as raltegravir-resistant HIV-1 variants. The lack of cross-resistance with other INSTIs and the absence of resistance selection in cell culture indicate the potential of HID derivatives compared to previous INSTIs. A crystal structure of MB-76 bound to the wild-type prototype foamy virus intasome reveals an overall binding mode similar to that of INSTIs. Its compact scaffold displays all three Mg(2+) chelating oxygen atoms from a single ring, ensuring that the only direct contacts with IN are the invariant P214 and Q215 residues of PFV IN (P145 and Q146 for HIV-1 IN, respectively), which may partially explain the difficulty of selecting replicating resistant variants. Moreover, the extended, dolutegravir-like linker connecting the MB-76 metal chelating core and p-fluorobenzyl group can provide additional flexibility in the perturbed active sites of raltegravir-resistant INs. The compound identified represents a potential candidate for further (pre)clinical development as next-generation HIV IN catalytic site inhibitor.

Topics: Catalytic Domain; Cell Line; HIV Infections; HIV Integrase; HIV Integrase Inhibitors; HIV-1; Humans; Isoquinolines; Models, Molecular