In vitro and in silico investigations of Propolis-derived phytochemicals as potential inhibitors of Plasmodium falciparum.

Background and aim: Malaria continues to pose a global health challenge, exacerbated by the emergence of drug-resistant strains of Plasmodium falciparum. This study aimed to evaluate the anti-Plasmodium potential of Propolis extracts collected from various Iranian regions and to characterize the molecular interactions of their bioactive phytochemicals with P. falciparum lactate dehydrogenase (PfLDH), a key enzyme in parasite glycolysis.

Materials and methods: The anti-Plasmodium activity of ethanol-extracted Propolis was assessed against P. falciparum NF54 using the SYBR Green I fluorescence assay. Gas chromatography-mass spectrometry (GC-MS) analysis identified major phytochemicals in the most active extract. Molecular docking and 100-ns molecular dynamic (MD) simulations were performed to evaluate the binding affinity and stability of selected compounds (tectochrysin and galangin) against PfLDH in both holo (Protein Data Bank [PDB] ID: 1LDG) and apo (PDB ID: 2X8L) forms.

Results: Propolis collected from Kermanshah city exhibited the highest anti-Plasmodium activity (IC₅₀ = 6.69 ± 1.44 μg/mL). GC-MS analysis identified tectochrysin and galangin as major constituents. Molecular docking revealed strong binding affinities of tectochrysin (-7.8 kcal/mol) and galangin (-7.5 kcal/mol) to PfLDH, surpassing the binding energies of standard antimalarial drugs (chloroquine and quinine). MD simulations confirmed the stability of tectochrysin and galangin within the PfLDH active sites, with favorable root mean square deviation, root mean square fluctuation, gyration, solvent-accessible surface area, molecular surface area, and polar surface area profiles, indicating persistent and stable protein-ligand interactions throughout the simulation.

Conclusion: The findings support the promising anti-Plasmodium potential of Propolis-derived compounds, particularly tectochrysin and galangin, as novel PfLDH inhibitors. Their potential applicability in transdisciplinary anti-parasitic therapy across human and veterinary medicine warrants further in vivo validation and clinical investigations.