Electrochemical study of quercetin-DNA interactions: part I. Analysis in incubated solutions

The present study aims to investigate the quercetin-deoxyribonucleic acid (DNA) interaction occurring in bulk solution either electrochemically using differential pulse voltammetry or spectrophotometrically, in order to explain the possible DNA-damaging activity of quercetin. A very weak interaction between quercetin and DNA in solution was found to take place. However, since extensive quercetin-induced DNA damage via reaction with Cu(II) has been reported, an electrochemical study of the DNA-Cu(II)-quercetin system in solution was undertaken. The product of DNA interaction with quercetin-Cu(II) complex was observed. Damages to DNA were electrochemically recognized via the increasing of the anodic peaks corresponding to the oxidation of guanosine and adenosine bases and spectrophotometrically via increasing of the 260 nm adsorption band. It was also observed that dsDNA damage produced by the quercetin-Cu(II) complex occurred with time. Control experiments with different mixtures of Cu(II), quercetin, ssDNA, dsDNA or poly[A] were carried out in order to establish a possible mechanism of interaction between DNA and quercetin via Cu(II).