Four new cytotoxic germacranolides from Carpesium divaricatum.
In a bioassay-guided search for cytotoxic compounds from higher plants of South Korea, four new sesquiterpenes of the germacranolide type, named cardivins A (1), B (2), C (3), and D (4), have been isolated from the aerial parts of Carpesium divaricatum. Structures of these compounds were elucidated on the basis of spectroscopic techniques. Compounds 1, 2, 3, and 4 showed cytotoxicity to the human tumor cells, A-549 (nonsmall cell lung), SK-OV-3 (ovary), SK-MEL-2 (skin), XF-498 (central nervous system), and HCT-15 (colon).