Phenyl substituted 3-hydroxypyridin-2(1H)-ones: Inhibitors of influenza A endonuclease

An Integrated Biological Approach to Guide the Development of Metal-Chelating Inhibitors of Influenza Virus PA Endonuclease

“…1). Among the various PA-Nter substrates that were reported to work (Dias et al, 2009;DuBois et al, 2012;Kowalinski et al, 2012;Parhi et al, 2013;Bauman et al, 2013;Datta et al, 2013;Chen et al, 2014), we chose the M13mp18 single-stranded DNA plasmid since it is commercially available. The active site substitution K134A in the PA-Nter enzyme completely abolished the endonucleolytic cleavage, in agreement with previous reports (Hara et al, 2006;Yuan et al, 2009;Crépin et al, 2010).…”

“…The catalytic site of the PA endonuclease, residing in its N-terminal part (PA-Nter; residues 1-256 or less), is highly conserved in influenza A and B viruses. Several crystallographic studies have revealed the protein structure of PA-Nter, which contains two (or possibly one or three) Mn 21 or Mg 21 ions in its catalytic core, although it is still unresolved which metal ions are present in native enzyme (Dias et al, 2009;Yuan et al, 2009;Zhao et al, 2009;DuBois et al, 2012;Kowalinski et al, 2012;Parhi et al, 2013). In biochemical assays, the enzyme's activity appears higher with manganese, but magnesium appears more biologically relevant since the intracellular concentration of free Mg 21 is .1000-fold higher than that of Mn 21 (Maret, 2010).…”

Structural and computational study on inhibitory compounds for endonuclease activity of influenza virus polymerase

“…This binding mode can be seen in a few other co-crystal structures of PA N and its inhibitors including 4M5U, 4LN7, and 4M4Q in PDB code, in which the p-fluorophenyl group of each inhibitor is extended toward the hydrophobic pocket likewise. 26,27 These findings suggest that the p-fluorophenyl group makes a substantial contribution to the inhibitory activity by interacting with Tyr24 or by being extended toward the hydrophobic pocket.…”

“…23,24 All of the inhibitors in the crystal structures, including N-hydroxyimide derivative, 4-substituted 2,4-dioxobutanoic acids, pyrimidinol derivatives, dihydroxybenzoic acid, and catechin derivatives, were found to chelate the two manganese ions in the active site. More recently, several studies with a structure-based drug design (SBDD) for influenza endonuclease activity were carried out, utilizing the crystal structures of PA N in complex with a series of endonuclease inhibitors including 3-hydroxyquinolinone derivative, 25 3-hydroxypyridinone derivatives, 26,27 and 5-hydroxypyrimidinone derivative. 28 In one of those studies, structural modification of 3-hydroxypyridinone derivatives led to a highly potent compound that showed an IC 50 value of 11 nM and ligand efficiency (LE) of 0.42 kcal/mol in an enzymatic assay and an EC 50 value of 11 μM in antiviral activity in cell culture.…”

“…27 Furthermore, a third metal binding site, which was not detected in the previous studies, was found at the active site cleft in some crystal structures, providing an additional hint for drug design. 26,27 Polyphenols, which are organic chemicals characterized by the presence of one or more phenol units, are contained in a wide variety of food including fruits, vegetables and cereals and also in beverages such as wine, coffee, cocoa, and tea. 29,30 So far, various polyphenolic compounds, including tea catechins, 31-33 resveratrol, 34 pomegranate polyphenols, 35 isoquercetin, 36 and macrocyclic bisbibenzyls, 37 have been shown to have antiviral activity against influenza virus by various inhibitory mechanisms.…”