Characterization of β-Carboline Derivatives Reveals a High Barrier to Resistance and Potent Activity against Ring-Stage and DHA-Induced Dormant Plasmodium falciparum.

Malaria, caused by Plasmodium falciparum, remains a major global health challenge, with an estimated 263 million new infections and 597,000 deaths annually. Increasing resistance to current antimalarial drugs underscores the urgent need for new therapeutics that target novel pathways in the parasite. We previously reported a novel class of β-carboline antimalarials, exemplified by PRC1584, which demonstrated a favorable oral pharmacokinetic profile, in vivo efficacy in Plasmodium berghei-infected mice, and no cross-resistance with other antimalarials in various P. falciparum strains. In this study, we demonstrate that PRC1584 exhibits a high resistance barrier and retains potent activity against fresh Ugandan P. falciparum isolates. PRC1584, along with its more potent analog PRC1697, demonstrated strong in vitro potency against both actively proliferating ring stages and dihydroartemisinin-induced dormant stages. Additionally, our study demonstrated that PfKelch13-C580Y mutation was associated with an increased susceptibility to PRC1584, whereas PfKelch13-R549T and Pfcoronin-R100 K-E107V mutations were not associated with this effect. These findings underscore the therapeutic potential of this new "irresistible" compound class, support a possible novel mechanism of action, and suggest the future development of novel ACTs active against resistant parasites by targeting DHA dormancy, an essential survival mechanism of P. falciparum.