A novel bicyclic 2,4-diaminopyrimidine inhibitor of Streptococcus suis dihydrofolate reductase

In vitro antifungal activity of MMV Pathogen Box® compounds alone or in combination with antifungal drugs against mucormycosis agents

Mucormycosis is a severe fungal infection that demands immediate and decisive intervention upon suspicion. The causative agents of mucormycosis exhibit inherent resistance to echinocandins and voriconazole, and their in vitro susceptibility to terbinafine is highly variable and species-specific. Considering these factors and the limitations of currently available antifungal therapies, the identification of novel antifungals with potent activity against mucormycosis is of paramount importance. This study aims to identify compounds from the MMV Pathogen Box® presenting antifungal activity against selected mucormycosis agents and to evaluate their potential synergistic effects when combined with antifungal drugs. A screening of the Pathogen Box® compounds was conducted, isolated or in combination with sub-inhibitory concentrations of amphotericin B, isavuconazole or posaconazole, against a Rhizopus oryzae strain. Hits from the screenings were further evaluated against eight Mucoralean strains for minimal inhibitory and fungicidal concentration determinations and to confirm synergistic interactions using the checkerboard method. Ultrastructural studies were performed using scanning electron microscopy. MMV675968 exhibited fungicidal activity against a R. oryzae strain. All but one Rhizopus spp. strains presented MIC ≤ 1 μg/mL, with a geometric mean of 0.78 μg/mL observed across all isolates for this compound, which did not change significantly the cellular structure of this fungus. The combination screening with antifungal drugs revealed six additional compounds potentially active against the R. oryzae strain, two of them demonstrated proven synergism through the checkerboard assay. This first study with the MMV Pathogen Box® and Zigomycetes highlights promising new treatment options for mucormycosis in the future.

Fighting Antibiotic Resistance: New Pyrimidine-Clubbed Benzimidazole Derivatives as Potential DHFR Inhibitors

The present work describes the design and development of seventeen pyrimidine-clubbed benzimidazole derivatives as potential dihydrofolate reductase (DHFR) inhibitors. These compounds were filtered by using ADMET, drug-likeness characteristics calculations, and molecular docking experiments. Compounds 27, 29, 30, 33, 37, 38, and 41 were chosen for the synthesis based on the results of the in silico screening. Each of the synthesized compounds was tested for its in vitro antibacterial and antifungal activities using a variety of strains. All the compounds showed antibacterial properties against Gram-positive bacteria (Staphylococcus aureus and Staphylococcus pyogenes) as well as Gram-negative bacteria (Escherichia coli and Pseudomonas aeruginosa). Most of the compounds either had a higher potency than chloramphenicol or an equivalent potency to ciprofloxacin. Compounds 29 and 33 were effective against all the bacterial and fungal strains. Finally, the 1,2,3,4-tetrahydropyrimidine-2-thiol derivatives with a 6-chloro-2-(chloromethyl)-1H-benzo[d]imidazole moiety are potent enough to be considered a promising lead for the discovery of an effective antibacterial agent.

Identification and validation of potent inhibitor of Escherichia coli DHFR from MMV pathogen box

The present study is conducted to find the solution of rising antimicrobial resistance (AMR) in Escherichia coli which is a pathogen responsible for fatal systemic infections in human and animals. The enzyme dihydrofolate reductase (DHFR) is found in all organisms. In this study DHFR of E. coli (ec-DHFR) and human DHFR (h-DHFR) is targeted by novel chemical entities (NCE) from the Pathogen box of Medicines for Malaria Venture, Switzerland (MMV) using molecular modelling. The in-silico studies were further validated by in-vitro assays. The virtual screening of 400 MMV compounds was conducted using PyRx standard tool followed by manual docking of selected compounds by Autodock vina and Ligplot program. The in-silico studies showed good binding energy and strong hydrogen bond in docking of MMV675968 with ec-DHFR and no hydrogen bond with h-DHFR. This was further validated by the Molecular dynamic studies that revealed high binding free energy in ec-DHFR and in-vitro assays that produced good synergy in combination study of MMV675968 with last line (meropenem) and last resort (colistin) antibiotics. The extensive MD simulation and energetic analysis thus concludes that MMV675968 targets ec-DHFR. The combination studies were conducted with MMV675968 and FDA approved drugs against a panel of multidrug resistant Escherichia coli isolates. The synergistic results obtained in combination studies concluded that in-vitro data is consistent with in-silico data and that MMV675968 is a potential lead for future process of antimicrobial drug development against the multidrug resistance E. coli.Communicated by Ramaswamy H. Sarma.