Virtual screening and molecular dynamics analysis of Plasmodium falciparum dihydroorotate dehydrogenase (DHODH) inhibitors targeting pyrimidine biosynthesis pathway.

Malaria caused by Plasmodium falciparum remains a major global health challenge, exacerbated by the emergence of resistance to artemisinin-based combination therapies. Dihydroorotate dehydrogenase (PfDHODH), an essential enzyme in parasite pyrimidine biosynthesis, represents a validated and selective antimalarial drug target. In this study, an integrated multilevel computational strategy was employed to identify novel PfDHODH inhibitors from a structurally diverse chemical library. Structure-based virtual screening yielded 1,500 initial hits, from which three top-ranking compounds (17507474, 24348860, and 17433008) were shortlisted based on binding affinity and active-site complementarity. Density functional theory analyses indicated favorable HOMO-LUMO energy gaps, suggesting chemical stability and reactivity conducive to biological activity. Redocking confirmed stable accommodation of optimized ligands within the PfDHODH catalytic pocket. Long-timescale molecular dynamics simulations (500 ns) demonstrated persistent binding stability of all complexes, with compound 24348860 exhibiting minimal structural deviation and compound 17433008 forming adaptive hydrogen-bonding networks. Principal component and free energy landscape analyses revealed well-defined low-energy conformational basins. MM/GBSA binding free energy calculations identified compounds 17433008 (- 86.46 kcal/mol) and 17507474 (- 85.91 kcal/mol) as the most thermodynamically favorable. Overall, these findings highlight the druggability of PfDHODH and propose compounds 17433008 and 17507474 as promising lead candidates for further experimental validation and antimalarial drug development.