No abstract

DNA gyrase and topoisomerase IV are well-validated pharmacological targets, and quinolone antibacterial drugs are marketed as their representative inhibitors. However, in recent years, resistance to these existing drugs has become a problem, and new chemical classes of antibiotics that can combat resistant strains of bacteria are strongly needed. In this study, we applied our hit-to-lead (H2L) chemistry for the identification of a new chemical class of GyrB/ParE inhibitors by efficient use of thermodynamic parameters. Investigation of the core fragments obtained by fragmentation of high-throughput screening hit compounds and subsequent expansion of the hit fragment was performed using isothermal titration calorimetry (ITC). The 8-(methylamino)-2-oxo-1,2-dihydroquinoline derivative 13e showed potent activity against Escherichia coli DNA gyrase with an IC50 value of 0.0017 μM. In this study, we demonstrated the use of ITC for primary fragment screening, followed by structural optimization to obtain lead compounds, which advanced into further optimization for creating novel antibacterial agents.

No abstract

The CC chemokines may play an important role in the pathogenesis of chronic inflammatory diseases including rheumatoid arthritis, and their effects are thought to be mediated through CCR1 receptors. Several nonpeptide CCR1 receptor antagonists that showed high affinity for human CCR1 receptors have been identified; however, their effectiveness in animal models of inflammatory diseases has been scarcely demonstrated, probably due to species selectivity of the antagonists. To elucidate the pathophysiological role of CCR1 receptors in murine models of disease, we looked for a potent antagonist for both murine and human CCR1 receptors. Screening of our chemical collection for inhibition of (125)I-MIP-1alpha binding to human CCR1 receptors transfected in CHO cells led to the identification of xanthene-9-carboxamide 1a as the lead compound. Derivatization of 1a by quaternarizing the piperidine nitrogen with various alkyl groups and by installing substituents into the xanthene moiety dramatically improved the inhibitory activity against both human and murine CCR1 receptors. As a result, 2q-1 showing IC(50) values of 0.9 and 5.8 nM for human and murine CCR1 receptors, respectively, was discovered. This compound is the first murine CCR1 receptor antagonist and may be a useful tool for clarifying the role of CCR1 receptors in murine models of disease.

No abstract