Ferrocenyl Quinoline-Benzimidazole Hybrids: A Multistage Strategy to Combat Drug-Resistant Malaria

Molecular hybridization and metal incorporation are widely employed strategies for drug development aimed at enhancing pharmacological efficacy while mitigating the emergence of drug resistance. The effectiveness of these approaches is supported by numerous studies demonstrating their success against a range of diseases. Despite the deployment of malaria vaccines, effective treatment remains hindered by the persistent emergence of drug-resistant Plasmodium falciparum strains, contributing to an alarming global disease burden. Inspired by the antimalarial candidate ferroquine, this study focused on the design and synthesis of ferrocenyl-based quinoline-benzimidazole molecular hybrids. The hybrids were evaluated for their in vitro blood-stage antiplasmodial activity against drug-sensitive NF54 and multidrug-resistant K1 P. falciparum strains, exhibiting potent submicromolar activity. Notably, incorporating an N,N-dimethylaminomethyl side chain significantly enhanced activity against both strains. Further assays revealed a compound with multistage antiplasmodial activity, targeting both immature and mature gametocytes. Mechanistic studies implicated the inhibition of hemozoin formation as a key mode of action, supported by in vitro cellular heme fractionation analysis. Additionally, fluorescence assays indicated the generation of reactive oxygen species under oxidative conditions, suggesting a complementary pathway contributing to the compounds' antiplasmodial activity. These findings highlight the potential of ferrocenyl-based molecular hybrids as promising candidates in antiplasmodial drug development.