Antioxidant and prooxidant effects of polyphenol compounds on copper-mediated DNA damage

Inhibition of copper-mediated DNA damage has been determined for several polyphenol compounds. The 50% inhibition concentration values (IC50) for most of the tested polyphenols are between 8 and 480 μM for copper-mediated DNA damage prevention. Although most tested polyphenols were antioxidants under these conditions, they generally inhibited CuI-mediated DNA damage less effectively than FeII-mediated damage, and some polyphenols also displayed prooxidant activity. Because semiquinone radicals and hydroxyl radical adducts were detected by EPR spectroscopy in solutions of polyphenols, CuI, and H2O2, it is likely that weak polyphenol-CuI interactions permit a redox-cycling mechanism, whereby the necessary reactants to cause DNA damage (CuI, H2O2, and reducing agents) are regenerated. The polyphenol compounds that prevent copper-mediated DNA damage likely follow a radical scavenging pathway as determined by EPR spectroscopy.

Graphical AbstractSemiquinone radicals can be generated from polyphenol compounds (R1 = H, OH for catechol or gallol, respectively) in the presence of CuII. Prooxidant and antioxidant behavior can be interpreted using EPR spectroscopy; similarly structured polyphenols may or may not behave similarly.Figure optionsDownload as PowerPoint slide