The isolation, structural elucidation, and antiprotozoal activities of habropetaline A, a novel naphthylisoquinoline alkaloid from Triphyophyllum peltatum, are-described. This alkaloid had previously only been identified on line, by the LC-MS/MS-NMR-CD triad, in the crude extract of the rare and difficult-to-provide related plant species Habropetalum dawei, whose small quantities available had not permitted to isolate the compound. As predicted by quantitative structure activity relationship (QSAR) investigations, habropetaline A exhibits strong antimalarial activity against Plasmodium falciparum, while it is inactive against other protozoal pathogens (Trypanosoma brucei rhodesience, T. cruzi, and Leishmania donovani). (C) 2003 Elsevier Science Ltd. All rights reserved.