Discovery of Potent Antimalarial Agents Targeting Plasmodium falciparum DNA Gyrase B by Integrating Computational and Experimental Approaches.

The global spread of drug-resistant Plasmodium falciparum, particularly artemisinin-resistant strains, underscores the urgent need for novel antimalarial agents with distinct mechanisms of action and improved therapeutic potential. In this study, we employed an integrated in silico and in vitro strategy to identify compounds with inhibitory activity against P. falciparum apicoplast Gyrase B (PfGyrB). High-throughput virtual screening identified hit compounds with favorable predicted interactions against the target protein, which were subsequently evaluated using biochemical ATPase inhibition and parasite growth inhibition assays. UNC8153 and Fexofenadine hydrochloride demonstrated time-dependent antiplasmodial activity, with lower IC50 values at 96 h than at 48 h under prolonged exposure conditions. UNC8153 exhibited greater antiplasmodial activity (~25-fold) than the reference compound novobiocin during the second intraerythrocytic cycle. Morphological analysis indicated impaired parasite development during the second intraerythrocytic cycle under prolonged exposure conditions. Importantly, UNC8153 retained inhibitory activity against the artemisinin-resistant C580Y strain and exhibited minimal cytotoxicity toward HEK-293 cells under the tested experimental conditions. Structural similarity analysis indicated that the identified compounds are chemically distinct from currently used antimalarial drugs, supporting their structural novelty. Collectively, these findings identify UNC8153 as a structurally distinct new antiplasmodial scaffold warranting further mechanistic, pharmacological, and in vivo evaluation.