Comparative phenolic profiling and antioxidant activity of Centaurea tougourensis Boiss. & Reut. and Centaurea dimorpha Viv. from Algeria

Centaurea L. plants are used in phytotherapy and as food. C. tougourensis (CT) and C. dimorpha (CD) are endemic of Algeria and have been scarcely studied up to now. Here, the phenolic content of their aerial parts was investigated using validated methods. Furthermore, the antioxidant properties of CT and CD were evaluated by performing DPPH, ABTS, FRAP, and phenanthroline assays. CD showed the highest total phenol (219.8 mg GAE/g) and total flavonoid (82.8 mg QE/g extract) contents. CT showed the highest flavonol content (46.3 mg QE/g). Chlorogenic acid, 4-OH-benzoic acid, and protocatechuic acid were the main compounds detected by LC-MS/MS. Several flavonoids were also detected in CD, while only hesperidin was detected in CT. Both the species showed antioxidant properties; however, radical scavenging activity and FRAP of CD were significantly higher than CT and were comparable with positive controls. Overall, this work affords a contribution to the characterisation and valorisation of the Algerian flora.