Inhibition assay of β-hematin formation initiated by lecithin for screening new antimalarial drugs

Measurement of heme crystallization provides a tool for screening new antimalarial drugs. Current assays for heme crystallization have employed initiators such as thermo, histidine-rich proteins, and lipids extracted from parasites and infected plasma. These initiators are unnatural or require laborious steps to prepare. In this study, we used a commercially available lipid, lecithin, a kind of phospholipid containing about 50% unsaturated fatty acids, as an initiator for heme crystal (β-hematin) formation. We demonstrated that the inhibition of lecithin-based β-hematin formation by antimalarial drugs is highly correlated with the preformed β-hematin-based method. In addition, the lecithin-based assay is sensitive and convenient for large-scale screening of new novel antimalarials. We also indicated that dimethyl sulfoxide is an ideal solvent for preparation of heme stock solution, which is stable and can be used for 1 month.