A New PqsR Inverse Agonist Potentiates Tobramycin Efficacy to Eradicate Pseudomonas aeruginosa Biofilms.

Pseudomonas aeruginosa (PA) infections can be notoriously difficult to treat and are often accompanied by the development of antimicrobial resistance (AMR). Quorum sensing inhibitors (QSI) acting on PqsR (MvfR) - a crucial transcriptional regulator serving major functions in PA virulence - can enhance antibiotic efficacy and eventually prevent the AMR. An integrated drug discovery campaign including design, medicinal chemistry-driven hit-to-lead optimization and in-depth biological profiling of a new QSI generation is reported. The QSI possess excellent activity in inhibiting pyocyanin production and PqsR reporter-gene with IC50 values as low as 200 and 11 × 10-9 m, respectively. Drug metabolism and pharmacokinetics (DMPK) as well as safety pharmacology studies especially highlight the promising translational properties of the lead QSI for pulmonary applications. Moreover, target engagement of the lead QSI is shown in a PA mucoid lung infection mouse model. Beyond that, a significant synergistic effect of a QSI-tobramycin (Tob) combination against PA biofilms using a tailor-made squalene-derived nanoparticle (NP) formulation, which enhance the minimum biofilm eradicating concentration (MBEC) of Tob more than 32-fold is demonstrated. The novel lead QSI and the accompanying NP formulation highlight the potential of adjunctive pathoblocker-mediated therapy against PA infections opening up avenues for preclinical development.

Design and synthesis of novel quinazoline derivatives and their evaluation as PI3Ks inhibitors.

The aim of this work was to synthesize 4-acetamido-, 4-amino- and 4-oxo-6-substituted aminoquinazolines and to evaluate them as phosphoinositide 3-kinases (PI3Ks) inhibitors. The respective chemotype was designed based on combining the structural features of two previously reported scaffolds acting as potent PI3Kγ inhibitors, which are quinazoline derivatives and amino-heterocyclic derivatives. In vitro enzymatic assay at 10 µM against all the eight human PI3K isoforms showed that an unsubstituted benzamide group at position 6 and an acetyl group at N(4) gave the best inhibitory activity on PI3Kγ. Interestingly, compounds 5a and 5e showed a significant, inhibitory effect on Class II PI3K-C2γ. This is of high value since there are very few inhibitors for this isoform reported in the literature.