Design and synthesis of novel Cystic Fibrosis (CF) modulators - Development of novel inhibitors of the anti-infective target DXS using Dynamic Combinatorial Chemistry (DCC)

Cystic Fibrosis (CF) is a lethal, autosomal recessive genetic disease characterized by an accumulation of viscous mucus at epithelia surface of multiple organs, including lungs, pancreas, gut and testis, which results in obstruction, infection, inflammation and ultimately organ failure. The primary cause of CF is the mutation of a gene, the Cystic Fibrosis Transmembrane conductance Regulator (CFTR), which leads to a decrease in CFTR chloride channel function and ultimately to a reduced ionic and water homeostasis at epithelial surfaces. Historically conventional CF treatments focused on symptomatic therapy, until recently when the growing understanding of the molecular basis of CF pathologies stimulated the development of small-molecule drugs, called CFTR modulators, which address the primary cause of CF with the hope to repair the defects in mutated CFTR. Aiming to expand the portfolio of novel modulators available to CF patients, also considering the relevant but limited pharmacological efficacy elicited by some of the current treatments, there is still the need to develop more CFTR small molecule modulators, primarily correctors, which may address the primary cause of CF by rescuing the activity of defective CFTR (Chapter 1). The present PhD thesis describes the design, synthesis and biological characterization of novel CFTR correctors. Starting from primary hits ARN9364 and ARN5562, selected for their promising initial biological activity after a High-Throughput Screening (HTS) campaign, new analogs were designed and synthesized to elucidate the Structure-Activity Relationship (SAR) patterns around these chemo-types (Chapter 2). The biological test of these novel compounds in a phenotypic cell-based assay (HS-YFP assay) using CFBE41o- cells, allowed to get clear information about the most suited structural modifications needed to improve rescuing activity of defective F508del-CFTR. An iterative process of design, synthesis and biological testing led to the identification of slightly or even more potent CFTR correctors (Chapter 3). In Chapter 4 the development of selective and potent inhibitors of the anti-infective target 1-deoxy-d-xylulose-5-phosphate synthase (DXS), using target-directed Dynamic Combinatorial Chemistry (tdDCC), as hit-identification strategy, was reported. Biochemical evaluation of several hit compounds amplified in the tdDCC experiment against M. tuberculosis DXS and D. radiodurans DXS afforded inhibitors with IC50 in the range of 30 microM – 190 microM.