Antioxidant effect of capsaicinoids on the metal-catalyzed lipid peroxidation

Antioxidant action of capsaicinoids was analyzed in relation to the role of transition metal. Capsaicin and dihydrocapsaicin inhibited the iron-mediat ed lipid peroxidation and copper-dependent oxidation of low density lipopro tein (LDL). Copper-dependent oxidation of LDL was also inhibited by additio n of superoxide dismutase, suggesting that superoxide radical is essential for the oxidation process. Capsaicinoids showed a potent copper-reducing ac tivity. Antioxidant properties of capsaicinoids can be explained by forming complexes with the reduced metals, which are inert to oxygen molecule, and also by chain-breaking reaction that donates hydrogen to radical intermedi ates.