Peroxide Antimalarial Drugs Target Redox Homeostasis in Plasmodium falciparum Infected Red Blood Cells

Plasmodium
falciparum causes the
most lethal form of malaria. Peroxide antimalarials based on artemisinin
underpin the frontline treatments for malaria, but artemisinin resistance
is rapidly spreading. Synthetic peroxide antimalarials, known as ozonides,
are in clinical development and offer a potential alternative. Here,
we used chemoproteomics to investigate the protein alkylation targets
of artemisinin and ozonide probes, including an analogue of the ozonide
clinical candidate, artefenomel. We greatly expanded the list of proteins
alkylated by peroxide antimalarials and identified significant enrichment
of redox-related proteins for both artemisinins and ozonides. Disrupted
redox homeostasis was confirmed by dynamic live imaging of the glutathione
redox potential using a genetically encoded redox-sensitive fluorescence-based
biosensor. Targeted liquid chromatography-mass spectrometry (LC-MS)-based
thiol metabolomics also confirmed changes in cellular thiol levels.
This work shows that peroxide antimalarials disproportionately alkylate
proteins involved in redox homeostasis and that disrupted redox processes
are involved in the mechanism of action of these important antimalarials.