Cytotoxic sesquiterpene lactones from Eupatorium kiirunense, a coastal plant of Taiwan

Phytochemical investigation of Eupatorium kiirunense has resulted in the isolation of eight new sesquiterpene lactones, constituted by five germacranolides, eupakirunsins A-E (1-5), and three heliangolides, eupaheliangolide A (6), 15-acetoxyheliangin (7), and 3-epi-heliangin (8), in addition to the known heliangin (9) and 8,10-epoxy-9-acetoxythymol angelate (10). The structures of the new compounds were established through detailed analysis of their spectroscopic data. Compounds 6, 8, and 9 exhibited cytotoxicity against human oral epidermoid (KB), cervical epitheloid (Hela), and liver (hepa59T/VGH) carcinoma cells.