Antimalarial sesquiterpene lactones from Distephanus angulifolius

Combined use of bioassay-guided fractionation based on in vitro antiplasmodial assay and dereplication based on HPLC-PDA-MS-SPE-NMR led to isolation of (6S,7R,8S)-14-acetoxy-8-[2-hydroxymethylacrylat]-15-helianga-1(10),4,11(13)-trien-15-al-6,12-olid and (5R,6R,7R,8S,10S)-14-acetoxy-8-12-hydroxymethylacrylat]-elema-1,3.11(13)-trien-15-al-6,12-olid, along with vernodalol, vernodalin, and 11,13 beta-dihydroxyvernodalin from extract of Distephanus angulifolius. All compounds were identified by spectroscopic methods, including ID and 21) homo- and heteronuclear NMR experiments. The isolated compounds showed IC50 values in the range 1.6-3.8 mu M and 2.1-4.9 mu M against chloroquine sensitive D10 and chloroquine resistant W2 Plasmodium falciparum strains, respectively. (C) 2009 Elsevier Ltd. All rights reserved.