Pyronaridine and chloroquine responses in the K1 strain

Pyronaridine (PN) and chloroquine (CQ) are structurally related anti-malarial drugs with primarily the same mode of action. However, PN is effective against several multidrug-resistant lines of Plasmodium falciparum, including CQ-resistant lines, suggestive of important operational differences between the two drugs. Synchronized trophozoite-stage cultures of P. falciparum strain K1 (CQ resistant) were exposed to 50% inhibitory concentrations (IC50) of PN and CQ, and parasites were harvested from culture after 4 and 24 hours exposure. Global transcriptional changes effected by drug treatment were investigated using DNA microarrays. Plasmodium falciparum in vitro cultures were synchronized to trophozoite stage (22-24h post infection) and exposed to either CQ or PN at IC50 concentrations. 18 sample pairs (drug treated/untreated) were analyzed; 9 for CQ and 9 for PN. All drug-treated samples were labelled with Cy5 and untreated controls were labelled with Cy3.