The application of supercritical carbon dioxide in the extraction of bioactive compounds from Helianthus annuus L. (sunflower) has been investigated. The influence of different variables, including pre-treatment of the sample, temperature and pressure, was investigated. The samples were either dried or congealed and the extraction conditions were as follows: temperatures of 35, 40. 45 and 50 degrees C, and pressures of 100, 200, 300, 400 and 500 bar. The best extraction yields were achieved on using a dried sample at a temperature of 50 degrees C and a pressure of 500 bar. The bioactivities of the extracts obtained under the different sets of conditions were compared. The best activity profiles were obtained for the dried samples extracted with supercritical carbon dioxide at 500 bar and congealed samples extracted at 50 degrees C and 500 bar. (C) 2007 Elsevier B.V. All rights reserved.