Two bisabolane-type sesquiterpenes, zingiberene-3,6-beta-endoperoxide
(1) and zingiberene-3,6-alpha-endoperoxide (2) have been isolated from
the aerial parts of Senecio selloi and Eupatorium rufescens. Their st
ructures were determined by spectroscopic methods. Both compounds show
schizonticidal activity against Plasmodium falciparum (EC(50) = 10 mu
g/ml).