Sesquiterpene lactones from the endemic Cape Verdean Artemisia gorgonum

Leaves and flowers of Artemisia gorgonum (Asteraceae) collected in Fogo, Cape Verde islands, were phytochemically investigated and resulted in isolation and characterization of three guaianolides 1, 2, 5, and a secoguainolide 4, in addition to eight known guaianolides 6-11 and two known germacranolides 12, 13. Structures were elucidated by 1D and 2D NMR experiments. Careful examination of the C-13 NMR spectrum led to revision of the structure of a previously described guaianolide from 2 to 3. Most compounds exhibited mild antiplasmodial activities, ridentin (13) being the most interesting with an IC50 of 3.8 +/- 10.7 mu g ml(-1) against Plasmodium falciparum FcB1 and weak cytotoxicity in a veto cell line (IC50 71.0 +/- 3.9 mu g ml(-1)). (C) 2008 Elsevier Ltd. All rights reserved.