Quercetin prevents DNA single strand breakage and cytotoxicity caused by tert-butylhydroperoxide: free radical scavenging versus iron chelating mechanism.

Although the antioxidant properties of flavonoids are well documented, it is still unclear whether these effects are dependent on radical scavenging or iron chelating activities. By using an experimental approach based on the notion that iron chelators suppress DNA strand scission and cytotoxicity caused by tert-butylhydroperoxide, whereas radical scavenging antioxidants prevent only the latter response, we provide experimental evidence indicating that the most prominent activity of the flavonoid quercetin resides in its ability to chelate iron. This experimental approach can be utilized for the assessment of iron chelation in the biological activity of flavonoids or other antioxidants.