Antioxidative properties of ferulic, sinapic, and tannic acids, and their co-pigment with an anthocyan molecule, malvin, were electrochemically observed by cyclic voltammetry. The values of oxidation potentials were used as a quantitative parameter in determining oxidation capabilities of the compounds. These values imply the following sequence of increasing antioxidative effect: ferulic acid < sinapic acid < tannic acid. Antioxidative capabilities of malvin co-pigments with the above acids are more pronounced in a buffer solution at pH 3.6 than in a solution at pH 2.5. The co-pigment malvin-ferulic acid oxidizes more easily than the other co-pigments of malvin with organic acids investigated. (C) 2003 Elsevier B.V. All rights reserved.