AbstractHere we show that lipid peroxidation of liposomal membranes was suppressed in the presence of Caroverine, a spasmolytic drug used in some countries. In order to understand the mechanism of this antioxidant action of Caroverine we studied the interaction of Caroverine with superoxide radicals, hydroxyl radicals and peroxynitrite. The results of the study show that the reaction of Caroverine with O radicals is of marginal significance. However, it is efficient in removing peroxynitrite and a particular high reaction constant was found for reaction with hydroxyl radicals. The strong antioxidant activity of Caroverine is therefore based both on the partial prevention of the formation and the highly active scavenging of hydroxyl radicals.