The indole alkaloid geissoschizoline (1) and two new derivatives, geissoschizoline N(4)-oxide (2) and 1,2-dehydrogeissoschizoline (3), were obtained from the bark of Geissospermum sericeum together with the beta-carboline alkaloid flavopereirine (4). The in vitro antiplasmodial activity of these compounds was evaluated in chloroquine-resistant (K1) and chloroquine-sensitive (T9-96) Plasmodium falciparum. Their cytotoxicity was determined in a human (KB) cell line.
