Isolation, characterization and in vitro cytotoxicity of new sesquiterpenoids from Achillea clavennae

Abstract

Further phytochemical investigation into the aerial parts of Achillea clavennae has resulted in the 3 isolation of three new sesquiterpene lactones: two highly oxygenated germacranolides (1, 2) and 4 the iso-seco-guaianolide, 9(R)-acetoxy-3-O-methyl-iso-seco-tanapartholide (3). Eight known 5 compounds were also found in this plant species, of which 9 α -acetoxycanin (5), sintenin (6) and 6 oleanolic acid (7) were detected for the first time. The structures of the isolated compounds were 7 elucidated by combined spectroscopic methods (1D and 2D NMR, HRESIMS, CIMS, FTIR). 8 While the predominant metabolite germacranolide sintenin (6) was not cytotoxic, the new iso-9 seco-guaianolide (3) displayed cytotoxicity comparable to that of cisplatin and the lactone 10 apressin (4), inducing partly apoptotic death in human U251 and rat C6 glioma cell lines.