1,2,4-Trioxane
The natural compound artemisinin , isolated from the sweet wormwood plant ( "Artemisia annua" ) , and some semi-synthetic derivatives are important antimalarial drugs containing the 1 , 2 , 4-trioxane ring . 
<triplet> artemisinin <subj> Artemisia annua <obj> natural product of taxon <triplet> Artemisia annua <subj> artemisinin <obj> this taxon is source of