Design and synthesis of simplified speciophylline analogues and β-carbolines as active molecules against Plasmodium falciparum.

A structure-activity relationship study of active molecules against chloroquine-resistant Plasmodium falciparum K1 strain is reported. Structurally simplified analogues of antiplasmodial active alkaloids presented similar levels of activity as their corresponding natural products extracted from Guiera senegalensis and Mitragyna inermis with IC50 values on chloroquine-resistant P. falciparum K1 strain of up to 10.6 μM for spirooxindoles and 13.8 μM for β-carbolines. The identification of such simpler and cheaper structural analogues is crucial to efficiently study these natural products' action mode as well as developing new cures against malaria.