Secondary metabolites of three endemic Centaurea L. species

Abstract

The aerial parts of three endemic Centaurea L. species, namely C. tomorosii Micevski, C. soskae Hayek and C. galicicae Micevski, afforded the sesquiterpene lactone cnicin (1) and seven flavonoids: apigenin (2), isokaempferide (3), hispidulin (4), eupatorin (5), cirsimaritin (6), santoflavone (7) and salvigenin (8). The structures of the isolated compounds were determined by UV, H-1-NMR and C-13-NMR spectroscopy and HR-ESI-MS spectrometry. H-1-NMR spectroscopy was used as a method for the quantitative analysis of cnicin.