Complexes involving quercetin, DNA and Cu(II).

The genotoxic flavonoid, quercetin, was shown to bind to both double-stranded and single-stranded DNA with concomitant changes in absorption spectrum and fluorescence emission spectrum of quercetin. Quercetin and Cu(II) were shown to form a charge transfer complex that decayed in oxygen-dependent reaction(s) and this decay was accelerated by DNA. Analysis of the three component system, DNA--querectin--Cu(II), led to a discussion of the complexes likely to be involved in the initial reactions that lead, ultimately, to strand scission of DNA.