Electrochemical studies on the binding of a carcinogenic anthraquinone dye, Purpurin (C.I. 58 205) with DNA

The interaction of the anthraquininoid dye, Purpurin (C.I. 58 205) with fish-sperm DNA was electrochemically investigated in 0.02 mol L−1 pH 7.0 Britton–Robinson (B–R) buffer. After interaction with DNA, the irreversible oxidation peak of the dye decreased and underwent a positive shift of potential, suggesting intercalation between the dye and DNA, this being consistent with fluorescence quenching results. The binding constant (K) and binding site size (s) of the two species were 9.6 × 106 L mol−1 and 1.7 respectively, as determined using voltammetric titration, indicating that the dye was strongly bound to the DNA.