ABSTRACT
The discovery and optimisation of a new class of benzothiazole small molecules that inhibit bacterial DNA gyrase and topoisomerase IV are described. Antibacterial properties have been demonstrated by activity against DNA gyrase ATPase and potent activity against Staphylococcus aureus, Enterococcus faecalis, Streptococcus pyogenes and Haemophilus influenzae. Further refinements to the scaffold designed to enhance drug-likeness included analogues bearing an α-substituent to the carboxylic acid group, resulting in excellent solubility and favourable pharmacokinetic properties.
Subject(s)
Benzothiazoles/chemistry , Benzothiazoles/pharmacology , DNA Topoisomerase IV/antagonists & inhibitors , Drug Design , Isonipecotic Acids/chemistry , Topoisomerase II Inhibitors/chemical synthesis , Topoisomerase II Inhibitors/pharmacology , Animals , Anti-Bacterial Agents/chemical synthesis , Anti-Bacterial Agents/chemistry , Anti-Bacterial Agents/pharmacokinetics , Anti-Bacterial Agents/pharmacology , Benzothiazoles/chemical synthesis , DNA Gyrase/chemistry , DNA Gyrase/metabolism , DNA Topoisomerase IV/metabolism , Enterococcus faecalis/drug effects , Enterococcus faecalis/enzymology , Enzyme Activation/drug effects , Haemophilus influenzae/drug effects , Haemophilus influenzae/enzymology , Half-Life , Mice , Microbial Sensitivity Tests , Rats , Staphylococcus aureus/drug effects , Staphylococcus aureus/enzymology , Streptococcus pyogenes/drug effects , Streptococcus pyogenes/enzymology , Topoisomerase II Inhibitors/chemistry , Topoisomerase II Inhibitors/pharmacokineticsABSTRACT
Despite their high clinical and socioeconomic impacts, there is currently no approved antiviral therapy for the prophylaxis or treatment of enterovirus infections. Here we report on a novel inhibitor of enterovirus replication, compound 1, 2-fluoro-4-(2-methyl-8-(3-(methylsulfonyl)benzylamino)imidazo[1,2-a]pyrazin-3-yl)phenol. This compound exhibited a broad spectrum of antiviral activity, as it inhibited all tested species of enteroviruses and rhinoviruses, with 50% effective concentrations ranging between 4 and 71 nM. After a lengthy resistance selection process, coxsackievirus mutants resistant to compound 1 were isolated that carried substitutions in their 3A protein. Remarkably, the same substitutions were recently shown to provide resistance to inhibitors of phosphatidylinositol 4-kinase IIIß (PI4KIIIß), a lipid kinase that is essential for enterovirus replication, suggesting that compound 1 may also target this host factor. Accordingly, compound 1 directly inhibited PI4KIIIß in an in vitro kinase activity assay. Furthermore, the compound strongly reduced the PI 4-phosphate levels of the Golgi complex in cells. Rescue of coxsackievirus replication in the presence of compound 1 by a mutant PI4KIIIß carrying a substitution in its ATP-binding pocket revealed that the compound directly binds the kinase at this site. Finally, we determined that an analogue of compound 1, 3-(3-fluoro-4-methoxyphenyl)-2-methyl-N-(pyridin-4-ylmethyl)imidazo[1,2-a]pyrazin-8-amine, is well tolerated in mice and has a dose-dependent protective activity in a coxsackievirus serotype B4-induced pancreatitis model.
Subject(s)
1-Phosphatidylinositol 4-Kinase/metabolism , Antiviral Agents/pharmacology , Antiviral Agents/therapeutic use , Enterovirus/drug effects , Enterovirus/metabolism , Animals , Enterovirus/pathogenicity , Enzyme Activation/drug effects , Fluorescent Antibody Technique , HeLa Cells , Humans , Male , Mice , Molecular Structure , Pancreatitis/drug therapy , Pancreatitis/metabolism , Virus Replication/drug effectsABSTRACT
Rhinovirus (genus enterovirus) infections are responsible for many of the severe exacerbations of asthma and chronic obstructive pulmonary disease. Other members of the genus can cause life-threatening acute neurological infections. There is currently no antiviral drug approved for the treatment of such infections. We have identified a series of potent, broad-spectrum antiviral compounds that inhibit the replication of the human rhinovirus, Coxsackie virus, poliovirus, and enterovirus-71. The mechanism of action of the compounds has been established as inhibition of a lipid kinase, PI4KIIIß. Inhibition of hepatitis C replication in a replicon assay correlated with enterovirus inhibition.
ABSTRACT
A novel class of mitogen-activated protein kinase-activated protein kinase 2 (MAPKAP-K2) inhibitors was discovered through screening a kinase-focused library. A homology model of MAPKAP-K2 was generated and used to guide the initial SAR studies and to rationalize the observed selectivity over CDK2. An X-ray crystal structure of a compound from the active series bound to crystalline MAPKAP-K2 confirmed the predicted binding mode. This has enabled the discovery of a series of pyrazolo[1,5-a]pyrimidine derivatives showing good in vitro cellular potency as anti-TNF-α agents and in vivo efficacy in a mouse model of endotoxin shock.
