Novel Quinazolinones Active against Multidrug-Resistant Mycobacterium Tuberculosis: Synthesis, Antimicrobial Evaluation, and in Silico Exploration of Penicillin-Binding Protein 1A as a Potential Target.

Quinazolinone derivatives have emerged as promising scaffolds in antimicrobial drug discovery. This work focuses on the design, synthesis, and evaluation of novel quinazolinone-based compounds and predicts their potential to interact with mycobacterial penicillin-binding proteins (PBPs). Relying on established structure-activity relationships of antibacterial quinazolinones, a total of 53 compounds belonging to three different structural types are synthesized and biologically evaluated for antimycobacterial, antibacterial, and antifungal activities. Biological evaluations reveal selective efficacy against Mycobacterium tuberculosis with minimum inhibitory concentrations (MICs) as low as 6.25 μg mL-1 for some derivatives, and this activity is preserved against drug-resistant strains. Molecular docking studies suggest a potential allosteric binding site in mycobacterial PBP 1A (PonA1, UniProt ID: P71707), and subsequential molecular dynamics confirm stable binding with key stabilizing interaction between the carbonyl oxygen of the quinazolinone and either ARG399 or ASP474. These findings suggest quinazolinone derivatives as viable candidates for further development as non-β-lactam PBP inhibitors, addressing the urgent need for new antitubercular therapies.