Synthesis, Characterization and Structural Elucidation of Biocompatible Hydroxychloroquine–Zinc Oxide Hybrid Nanoclusters as Synergistic Antiplasmodial Agents

Background: The increasing emergence of antimalarial drug resistance and safety concerns associated with conventional therapies necessitates the development of improved compounds. In this study, we report the synthesis of hydroxychloroquine–zinc oxide hybrid nanoclusters (HCQ-ZnONPs) by integrating a bioactive organic ligand (hydroxychloroquine) with a bioactive metal oxide nanocluster (ZnONPs). Methods: Structural and physicochemical characterization was performed using proton nuclear magnetic resonance (1H NMR), fourier-transform infrared spectroscopy (FT-IR), mass spectrometry, X-ray diffraction (XRD), transmission electron microscopy (TEM), field emission scanning electron microscopy (FE-SEM), energy-dispersive X-ray analysis (EDAX), dynamic light scattering (DLS), and zeta potential. Molecular docking against Plasmodium falciparum dihydrofolate reductase–thymidylate synthase (PfDHFR-TS) was performed to investigate potential ligand–target interactions. Drug loading and HCQ release were evaluated at pH 7.4. We also assessed in vitro cytocompatibility, nitric oxide estimation, total antioxidant capacity, anti-inflammatory and antimalarial activities. Results: The physicochemical characterization supported the successful formation of HCQ-ZnONPs. In the proposed model of HCQ-ZnONPs, a quinoline nitrogen of the HCQ molecule interacts with an exposed Zn2+ site on the surface of a ZnONPs cluster. The HCQ-ZnONPs exhibited a drug loading of 21.4% and showed approximately 48.4% cumulative HCQ release over 24 h at pH 7.4. To the best of our knowledge, this is the first report of an HCQ-ZnONPs nanocluster system. Biological evaluation demonstrated synergistic in vitro antimalarial activity, indicating enhanced efficacy compared with the parent drug, suggesting that this arises from the integration of HCQ and ZnO nanoclusters while maintaining favorable cytocompatibility in Vero cells. The oxidative stress and anti-inflammatory potential of the hybrid complex was also assessed, highlighting its multifunctional biological profile that may be advantageous for mitigating malaria-associated oxidative stress and inflammatory responses. Molecular docking against PfDHFR-TSfurther supported favorable ligand-target interactions and provided additional insight into the potential molecular basis of the observed biological activity. Conclusions: Collectively, the experimental, theoretical, and mathematical analysis suggests the successful formation of HCQ-ZnONPs with promising anti-inflammatory and antimalarial efficacy, establishing this hybrid nano system as a potential candidate for next-generation antiplasmodial therapy.