Lactones from species from Centaurea. Cytotoxic and antimicrobial activities

Some germacranolides and the new natural product (+)-tulipalin B (3) were isolated from four species of the Centaurea genus. The absolute configuration of the chiral center of the side chain of cnicin (1) was determined as R. The cytotoxic and antimicrobial activities of the natural lactones and their derivatives were screened.