Guaiane-rich phytochemical profile of Centaurea kotschyi subsp. persica (Boiss.) Wagenitz and identification of hypoglycaemic metabolites

: Phytochemical investigation of the aerial parts obtained from the Turkish plant Centaurea kotschyi subsp. persica led to the isolation of nine sesquiterpene lactones belonging to the guaiane class, including the undescribed kotschyols A and B, a monoterpene lactone (daphnauranin E), four known lignans (matairesinol, matairesinoside, arctiin and arctigenin) and an undescribed dihydrobenzofuran neolignan (4-O-glucosylcrataegifin A). The structures of these compounds were defined by spectroscopic analysis, including ECD and 1D/2D NMR, and chemical conversion. Spurred from the traditional use of C. kotschyi subsp. persica and previous reports on the activity of its extracts, the isolated compounds were evaluated for their hypoglycaemic activity disclosing the bioactive components.