Acridinediones have previously been shown to have potent antimalarial activity. A series of sulfur isosteres of acridinediones have been synthesized and evaluated for their inhibition of the Plasmodium falciparum cysteine protease falcipain and for their antimalarial activity. A number of these phenothiazines inhibited falcipain and demonstrated activity against cultured P. falciparum parasites at low micromolar concentrations. We propose that the ...
