Sesquiterpene lactones from Centaurea spinosa and their antibacterial and cytotoxic activities

Ten sesquiterpene lactones, 8α-O-(3,4-dihydroxy-2- methylenebutanoyloxy)sonchucarpolide (4-epi-malacitanolide) (1), 8α-O-(4-acetoxy-2-hydroxymethylbuten-2-oyloxy)-4-epi-sonchucarpolide (2), malacitanolide (3), its 4′-acetyl derivative (4), 8α-O-(3,4- dihydroxy-2-metnylenebutanoyloxy)dehydromelitensine (5), 8α-O-(3,4- dihydroxy-2-methylenebutanoyloxy)-15-oxo-5,7αH,6βH-eleman-1,3,11(13) -trien-6,12-olide (6), the germacranolides 8α-O-(4-acetoxy-2- hydroxymethylbuten-2-oyloxy)salonitenolide (7), cnicin (8), and 4′-acetylcnicin (9), and the sesquiterpene methyl 8α-O-(3,4- dihydroxy-2-methylenebutanoyloxy)-6α,15-dihydroxyelema-1,3,11(13) -trien-12-oate (10), were isolated from the aerial parts of Centaurea spinosa. Nine known flavonoids were also isolated. The structures and the stereochemistry of the new compounds 1 and 2 were deduced by spectroscopic methods. The in vitro activity of 1-10 against three Gram-positive and three Gram-negative bacteria was evaluated using a microdilution method, and their in vitro cytotoxic activity was determined against a panel of human tumor cell lines. © 2005 American Chemical Society and American Society of Pharmacognosy.