Sesquiterpene lactones from Achillea asplenifolia

Fifteen new sesquiterpene lactones (nine guaianolides and six germacranolides), in addition to seven known lactones have been isolated from the flower heads of Achillea asplenifolia Vent. of Bulgarian origin. The structures and stereochemistry were elucidated on the basis of spectral data. The chemotaxonomic relevance of sesquiterpene lactones is discussed.