Inhibition of dihydrofolate reductase from Mycobacterium tuberculosis and pathogenic fungi by antimicrobials identified by Fragment-Based Drug Discovery

Abstract

It is urgent to discover new antimicrobials to control bacterial and fungal infectious diseases, such as those caused by Mycobacterium tuberculosis (Mtb), Aspergillus fumigatus, Paracoccidioides brasiliensis and Candida auris. The increasing emergence of multidrug-resistant strains and the high systemic toxicity of current treatments further limit the therapeutic options for these infections and contribute to increased morbidity and mortality rates. A promising therapeutic target for the development of new antimicrobials is the enzyme dihydrofolate reductase (DHFR), essential for microbial metabolism and growth, which acts in a crucial step in the tetrahydrofolate biosynthesis pathway. Despite the scarcity of studies in pathogenic fungi, DHFR enzyme is a validated pharmacological target inhibited by antimicrobials trimethoprim and pyrimethamine. Therefore, in this project we propose to continue a fragment-based strategy (FBDD) to identify antimicrobials that inhibit the DHFR of Mtb (MtDHFR) and C. auris (CauDHFR), an approach already undertaken by our group. Additionally, we aim to extend the application of this technique to the DHFRs of two other pathogenic fungi, A. fumigatus (AfDHFR) and P. brasiliensis (PbDHFR). The compounds and/or fragments identified applying the FBDD strategy will be subjected to different biophysical and biochemical techniques to characterize the interaction between the fragments and the target enzymes of the project. Through fragment screening and hit validation, new compounds will be obtained through structure-activity relationship (SAR) by catalog or organic synthesis performed by collaborators. Selective inhibition of the enzymes of interest will also be evaluated by comparing interactions with human DHFR (HsDHFR). Furthermore, we hope to carry out the structural characterization of PbDHFR and AfDHFR, which have not yet been described in the literature. Finally, we hope at the end of the project to have compounds that can be tested against different cultures of microorganisms.