Prooxidative Activities of Tea Catechins in the Presence of Cu²⁺

Abstract

The ability of various tea catechins to generate H₂O₂ and the hydroxyl radical in the presence of the Cu²⁺ ion was investigated and compared with the effect of iron ions. The presence of Cu²⁺ accelerated the generation of H₂O₂ by EGC, while EGCg with Cu²⁺ generated a little H₂O₂. The presence of iron ions inhibited the generation of H₂O₂ by EGC. EGC and EC with Cu²⁺ generated the hydroxyl radical, while EGCg and ECg with Cu²⁺ did not. The fact that EGCg showed less prooxidative activity than EGC can be explained by the chelating ability of catechin gallates to metal ions under the experimental conditions.