Guaianolides and lignans from the aerial parts of Centaurea ptosimopappa

The genus Centaurea L. (Asteraceae, tribe Cardueae, subtribe Centaureinae) comprises ca. 600 species distributed in Asia, Europa, North Africa and America (Hickey and King, 1981; Heywood, 1979). Turkish flora numbers 187 species, 114 of which being endemic (Davis, 1975; Davis et al., 1988; Wagenitz et al., 1988; Guner et al., 2000; Duran and Duman, 2000; Turkoglu et al., 2003). Centaurea ptosimopappa Hayek is an endemic species distributed in the Mediterranean and South-Eastern Anatolian regions of Turkey; widespread and locally frequent in the Amanos and Casus mountains (Davis, 1975; Reeves and Adigüzel, 2004). Aerial parts of C. ptosimopappa were collected in Hatay, the Amanos Mountain above Dörtyol (Turkey), 850e950 m above sea level in June 2003 (36 510 N, 36 130 E). Voucher specimens (Celik 2148e2153) are deposited at the Department of Biology, Çanakkale Onsekiz Mart University.