Novel strategies against infectious diseases: leveraging small molecules and insights into pathogen biology

Nowadays, the discovery of new drugs for the treatment and eradication of infectious diseases remains a formidable challenge, exacerbated by the urgent threat of antibiotic resistance. In the past decade, efforts in malaria drug research and development have intensified. The inefficacy of current malaria interventions is largely driven by the spreading of resistance of Plasmodium falciparum parasites to existing drug regimens, and the resistance of the malaria vector, Anopheles mosquito, to insecticides. Most available drugs target the asexual blood stages of the parasite’s life cycle. Therefore, one strategy to overcome resistance is to target other stages, such as the sexual stages of development, exploiting the susceptibility of Plasmodium population bottlenecks before transmission (gametocytes) and within the mosquito vector (gametes, zygotes, ookinetes, oocysts, sporozoites). In this context, we developed transmission-blocking compounds, at first by synthesizing analogues of pyrazole MMV1580843, identified in a high-throughput screening as a potent and selective gametocytocidal compound. This PhD thesis explores the potential of modifying the pyrazole core with a pyrrole core and various substitution around the central core to maintain activity against late-stage gametocytes, while ensuring favorable physicochemical and safety profile. Tuberculosis remains a major global cause of morbidity and mortality, with 10 million new cases and approximately 1.5 million deaths annually. The emergence of Mycobacterium tuberculosis resistant strains makes it a priority to discover novel and innovative drugs. The research group where I carried out my PhD thesis, has identified potent antimycobacterial agents targeting the MmpL3 protein. Initial hit-to-lead optimization led to the identification of the pyrrole BM635, which was further optimized to yield the pyrazole BM859, a potent antitubercular compound. This thesis presents the design and synthesis of various analogues of pyrazole BM859, aiming to enrich the structure-activity relationship analysis of this class of potent antimycobacterial compounds. Concurrently, target validation was performed using native Mass Spectrometry to assess the effect of our compounds against the MmpL3 protein. Additionally, native Mass Spectrometry was employed to address fundamental questions regarding the recycling of undecaprenyl phosphate (UndP or C55P) at the end of the peptidoglycan pathway. Peptidoglycan, a crucial component of the bacterial cell wall, represents a promising target for antibiotic development. The translocation of C55P is facilitated by DedA and DUF368 domain-containing family membrane proteins through unknown mechanisms. This study aimed to use native Mass Spectrometry to investigate the interactions between Bacillus subtilis UptA and C55P, membrane phospholipids and cell wall-targeting antibiotics.