Chemical constituents of Centaurea omphalotricha Coss. & Durieu ex Batt. & Trab.

The investigation of the aerial parts of Centaurea omphalotricha Coss. & Durieu ex Batt. & Trab. allowed the isolation of nine secondary metabolites corresponding to five flavonoids: oroxylin A (1), chrysin (2), tenaxin II (3), 5,7,2’-trihydroxyflavone (4) and quercetin (5), and four triterpenoids: lupeol (6), taraxasterol (7), daucosterol (8) and β-sitosterol (9). Their structures were established by spectroscopic methods such as 1H and 13C NMR, COSY, HSQC, and HMBC experiments, and ESI-MS, and comparison with literature data. The flavonoids tenaxin II (3) and 5,7,2’-trihydroxyflavone (4) are new for the genus Centaurea L