Extracts obtained from aerial parts of eight Centaurea L. (Asteraceae) species (C. calolepis, C. cariensis subsp. maculiceps, C. cariensis subsp. microlepis, C. hierapolitana, C. cadmea, C. ensiformis, C. depressa and C. urvillei subsp. urvillei), were tested for their free radical scavenging activity (FRSA) in the DPPH screening assay, for their in vitro antiinflammatory activity in the reporter gene assay for inhibition of transcription factor NF-kappa B and for their total phenolic content. Methanol extracts (0.25 mg/4 mL) of C. urvillei, C. cadmea and C. ensiformis showed strong antioxidant activity with 90.41 +/- 2.98%, 86.66 +/- 2.67% and 86.19 +/- 2.94% FRSA, respectively. Antioxidant capacity results were consistent with the total phenolic content. Chloroform extracts of C. hierapolitana, C. calolepis and C. cadmea showed strong in vitro antiinflammatory activity with IC50 values of 2.5, 4.4 and 6.2 mu g/mL, respectively. Copyright (c) 2007 John Wiley & Sons, Ltd.