Cytotoxic sesquiterpene lactones from Saussurea calcicola.

Seven sesquiterpene lactones were isolated by the chromatographic separation of the MeOH extract of the aerial parts of Saussurea calcicola (Compositae). Their structures were determined spectroscopically to be cynaropicrin (1), arguerin B (2), cebellin F (3), 8alpha-hydroxy-11alpha, 13-dihydrozaluzanin C (4), desacylcynaropicrin (5), 3beta-hydroxy-8alpha-epoxymethylacriloiloxy-4(15),10(14),11(13)-trien-guaian-6,12-olide (6), and kandavanolide (7). Compounds 1 and 2 showed significant cytotoxicity against five cultured human tumor cell lines with ED50 values ranging from 0.23-1.72 microg/mL.