Dual effects of (þ)-catechin on hemin-induced oxidative reactions: A potential pharmacological implication

Abstract

Introduction: Although the anti- and pro-oxidant properties were the well-known phenomenons for flavonoids, the influence of flavonoids on free heme-dependent redox reactions was not definitely elucidated. Methods: By spectrophotometry and Western blotting, the influence of (+)-catechin (a polyphenol identified in red wine, tea, and cocoa) on hemin-induced oxidative reactions was investigated in this study. Results: (+)-Catechin was found to act as an efficient reducing agent for the reduction of ferryl heme to ferric state, demonstrating novel anti-oxidant pathway. However, this antioxidant had the ability to trigger hemin oxidation through producing additional hydrogen peroxide (H₂O₂). On the other hand, the effects of (+)-catechin on hemin-H₂O₂-induced protein (or methylene blue) oxidation depended on the concentrations of H₂O₂ and antioxidant. (+)-Catechin exerted significant anti-oxidant ability when lower concentration of H₂O₂ was used. However, in the presence of higher concentration of H₂O₂, (+)-catechin at low concentrations could significantly aggravate oxidative reactions and exhibit protective effects at high concentrations. Conclusions: The anti- and pro-oxidant effects of catechin on heme-dependent redox reactions at different concentration, may provide new insights into the dietary intake and therapeutic implications of catechins with free heme and heme proteins.