Six new sesquiterpene coumarin ethers, namely turcicanol A (1), turcicanol A acetate (2), turcicanol B (3), turcica ketone (4), 11′-dehydrokaratavicinol (5), and galbanaldehyde (6), and one new sulfur-containing compound, namely turcicasulphide (7), along with thirty-two known secondary metabolites were isolated from the root of the endemic species Ferula turcica Akalın, Miski, & Tuncay through a bioassay-guided isolation approach. The structures of the new compounds were elucidated by spectroscopic analysis and comparison with the literature. Cell growth inhibition of colon cancer cell lines (COLO205 and HCT116) and kidney cancer cell lines (UO31 and A498) was used to guide isolation. Seventeen of the compounds showed significant activity against the cell lines.

Four new sesquiterpene coumarin ethers (1–4) and a new phenylpropanoid compound (5) were isolated from a hexane extract of the roots of Ferula drudeana, the putative Anatolian ecotype of the silphion plant, in addition to nineteen previously described sesquiterpene coumarins (6–24) and four known phenylpropanoid derivatives (25–28). The structures of these compounds were elucidated by extensive spectroscopic analysis and computational studies. The cytotoxic activities of all isolated compounds were evaluated on renal, malignant pleural mesothelioma (MPM) and colon cancer cell lines. While 11 sesquiterpene coumarin derivatives showed strong-to-moderate cytotoxic activity against the UO31 renal cancer cell line, 13 compounds showed strong cytotoxic activity against the MPM cell line, and four sesquiterpene coumarin derivatives displayed moderate cytotoxic activity against the colon cancer cell line.