Reactive oxygen species (ROS) play a critical role in cardiovascular diseases, inflammatory diseases, neurodegenerative disorders, cancer and aging. Diets rich in foods containing antioxidants, such as fruits and vegetables, could help to prevent these pathologies. Wheat and Brussels sprouts contain antioxidant compounds active in the protection of DNA against the oxidative stress induced by ROS. The aim of this work was to determine antioxidant activity of aqueous and ethanol extracts from savoy cabbage (Brassica oleracea L. var. sabauda) sprout powder. Significant values of antioxidant activity were found in both extracts using 1,1-diphenyl-2-picrylhydrazyl (DPPH) and 2,2'-azino-bis(3-ethylbenzthiazoline-6-sulphonic acid) (ABTS) radical scavenging assays. 2',7'-dichlorofluorescin-diacetate (DCFH-DA), a useful indicator of ROS, was used to determine the antioxidant and prooxidant activity of sprout extracts in a cell-based assay (human dermal cell line). Results show a dose-dependent prooxidant activity of aqueous sprout extract, higher than ethanol extract. The prooxidant activity was correlated with the inhibition of cell proliferation. Interestingly, the boiling of aqueous extract inhibits this prooxidant effect, restore cell proliferation without affecting the antioxidant effect in vitro.