Methyl sulfonamide substituents improve the pharmacokinetic properties of bicyclic 2-pyridone based:Chlamydia trachomatis inhibitors

Chlamydia trachomatis infections are a global health problem and new approaches to treat C. trachomatis with drugs of high specificity would be valuable. A library of substituted ring fused 2-pyridones has been synthesized and evaluated for their ability to attenuate C. trachomatis infectivity. In vivo pharmacokinetic studies were performed, with the best candidates demonstrating that a C8-methylsulfonamide substituent improved pharmacokinetic properties important for oral administration. C8-Methyl sulfonamide analogue 30 inhibited C. trachomatis infectivity in low micromolar concentrations. Further pharmacokinetic evaluation at an oral dose of 10 mg kg(-1) showed an apparent bioavailability of 41%, compared to C8-cyclopropyl and -methoxy analogues which had negligible oral uptake. In vitro ADME (absorption, distribution, metabolism and excretion) testing of solubility and Caco-2 cell permeability revealed that both solubility and permeability is greatly improved with the C8-methyl sulfonamide 30, effectively moving it from BCS (Biopharmaceutical Classification System) class IV to II

Design, syntes och utvärdering av substituerade ringsammansatta 2-pyridoner med biologisk aktivitet mot Listeria monocytogenes och Chlamydia trachomatis

Antibiotic resistance has become a global health burden with the number of resistant bacteria continuously increasing. Antibiotic drugs act by being either bactericidal (killing bacteria) or bacteriostatic (inhibiting growth of bacteria). However, these modes of action increase the selective pressure on the bacteria. An alternative treatment strategy to antibiotics is anti-virulence therapies that inhibits virulence of the pathogenic bacteria. The term “virulence” summarises a number of factors that the bacteria need to colonise a new niche and as a consequence its ability to infect and cause diseases. By inhibiting virulence, instead of killing, the selective pressure on the bacteria can be reduced and consequently decreases the rapid development of resistance. This thesis describes two projects focusing on development of anti-virulence agents, with the ring-fused 2-pyridone scaffold as the central character, targeting the bacteria Listeria monocytogenes and Chlamydia trachomatis. The first project is targeting L. monocytogenes, which is the cause for listeriosis in humans. This can develop into life-threatening encephalitis and meningitis as well as cause severe complications for developing fetus. The target in L. monocytogenes is the transcriptional regulator PrfA that control almost all virulence factors in this bacterium. We have designed and synthesised potent substituted ring-fused 2-pyridones, which at low micromolar concentrations block activation of the virulence regulator PrfA and thus attenuate the bacterial infection. Co-crystallisation of the active ring-fused 2-pyridones with PrfA resulted in determination of the exact substance interaction site in the protein. This facilitated further structure-based design that resulted in improved compounds capable of attenuating L. monocytogenes in an in vivo model. The second project targets C. trachomatis, which is the causative agent behind the most common sexually transmitted infection as well as the eye infection trachoma. By structure-activity relationship analysis of previously tested ring-fused 2-pyridones, we have designed and synthesised non-hydrolysable ring-fused 2-pyridone amide isosteres. The most potent analogues inhibit C. trachomatis infectivity at low nanomolar concentrations, without showing host cell toxicity or affecting the viability of commensal microbiota. Introduction of heteroatom substituents at specific sites of the ring-fused 2-pyridone scaffold, resulted in improved pharmacokinetic properties of the analogues and further evaluation in vivo was performed

Structure-Based Design of Inhibitors Targeting PrfA, the Master Virulence Regulator of Listeria monocytogenes

<i>Listeria monocytogenes</i> is a bacterial pathogen that controls much of its virulence through the transcriptional regulator PrfA. In this study, we describe structure-guided design and synthesis of a set of PrfA inhibitors based on ring-fused 2-pyridone heterocycles. Our most effective compound decreased virulence factor expression, reduced bacterial uptake into eukaryotic cells, and improved survival of chicken embryos infected with <i>L. monocytogenes</i> compared to previously identified compounds. Crystal structures identified an intraprotein “tunnel” as the main inhibitor binding site (A_I), where the compounds participate in an extensive hydrophobic network that restricts the protein’s ability to form functional DNA-binding helix–turn–helix (HTH) motifs. Our studies also revealed a hitherto unsuspected structural plasticity of the HTH motif. In conclusion, we have designed 2-pyridone analogues that function as site-A_I selective PrfA inhibitors with potent antivirulence properties