Acrifolide, A Novel Sesquiterpene Lactone from Achillea crithmifolia

Abstract A new highly oxygenated sesquiterpene lactone with the rare 4-methyl-7-isopropyl-9-ethyl-perhydroindene skeleton, named acrifolide, was isolated as minor constituent from the aerial parts of Achillea crithmifolia. Its structure was elucidated by spectral methods.