Indolyl-3-ethanone-α-thioethers: A promising new class of non-toxic antimalarial agents

• We describe the discovery of indolyl-3-ethanone-α-thioethers as a new class of antimalarial agents.
• SAR investigations uncovered two low nanomolar inhibitors of whole cell Plasmodium falciparum.
• Majority of compounds explored exhibited no measurable toxicity to HeLa cells.

The success of chemotherapeutics in easing the burden of malaria is under continuous threat from ever-evolving parasite resistance, including resistance to artemisinin combination therapies. Therefore, the discovery of new classes of antimalarials which inhibit new biological targets is imperative to controlling malaria. Accordingly, we report here the discovery of indolyl-3-ethanone-α-thioethers, a new class of antimalarial compounds with encouraging activity. Synthesis of a focused library of compounds revealed important insight into the SAR of this class of compounds, including critical information regarding the position and chemical nature of substituents on both the thiophenol and indole rings. This investigation ultimately led to the discovery of two hit compounds (16 and 27) which exhibited nano molar in vitro antimalarial activity coupled to no observable toxicity against a HeLa cell line.

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