Antiproliferative activity against leukemia cells of sesquiterpene lactones from the Turkish endemic plant Centaurea drabifolia subsp. detonsa.

The apolar organic extract obtained from aerial parts of Centaurea drabifolia Sibth. & Sm. subsp. detonsa (Bornm.) Wagenitz, growing wild in Turkey, was investigated for the first time for its secondary metabolite composition. Seven sesquiterpene lactones belonging to the guaiane class ( 1 – 7 ), including the new compound 4 , along with a fatty acid lactone derivative ( 8 ), were isolated. The structures of these compounds were established by spectroscopic analysis, including 2D NMR spectroscopic techniques, with the stereostructure of the new guaiane 4 determined with the help of MTPA derivatization. Cytotoxic activities of compounds 1 – 7 were evaluated against two cancer cell lines, namely acute lymphoblastic leukemia (CCRF-CEM) and its multidrug-resistant subline CEM/ADR5000. Results showed that aguerin B ( 1 ) and cynaropicrin ( 2 ) showed a potent activity on both cell lines revealing interesting details about the structure-activity relationships in the class of acylated guaiane sesquiterpenes. [ABSTRACT FROM AUTHOR]