Germacranolide type sesquiterpene lactones from Neurolaena macrocephala

Two new neurolenin-type sesquiterpene lactones were found in the leaves of Neurolaena macrocephala Sch. Bip. Ex Hemsl. (Asteraceae). These compounds were identified by their NMR spectra as the 8β-isobutyryloxy- and 8β- (2-methyl)butyryloxy analogs of neurolenin B. Additionally, the known neurolenins B, C and D and the furanoheliangolide 9a-acetoxy-8β-isovaleryloxy-calyculatolide were found to be present in this species.