Antioxidant properties of ferrous catechin complexes

Interaction of metal, especially iron ions with catechins is considered as an important feature of these compounds and is believed to contribute to their both antioxidant and prooxidant properties. The aim of this study was to examine how Fe2+binding to form a 1:1 complex affects the antioxidant properties of catechins (flavan-3-ols). The following catechins were used in the study: (-)-epigallocatechin gallate, (−)-epicatechin, (−)-epigallocatechin, (−)-epicatechin gallate and (+)-catechin. They represent the main catechins present in the green tea. Iron complexes of various stoichiometry can be formed, but under the conditions of catechin excess, formation of 1:1 complexes can be expected ABTS* scavenging, protection against fluorescence bleaching induced by AAPH and hypochlorite, and protection against hypochlorite-induced hemolysis demonstrated that catechin-Fe2+complexes retain antioxidant properties, although, in most cases, they are lower with respect to uncomplexed catechins. No superoxide dismutase-like or catalase-like activity of the complexes was revealed.