Interaction of antioxidant flavonoids with calf thymus DNA analyzed by spectroscopic and electrochemical methods.

Mechanism of interaction of bioactive flavonoids, hesperitin (HES) and naringenin (NAR) with calf thymus deoxyribonucleic acid (DNA) was studied employing UV absorption, fluorescence, circular dichroism, melting temperature, fluorescence anisotropy and differential pulse voltammetric methods. The observed fluorescence quenching of DNA-ethidium bromide system by the flavonoid indicated the intercalative mode of binding between the flavonoid and DNA. Stern-Volmer plots have revealed the presence of static quenching mechanism. Binding and thermodynamic characteristics of interaction were evaluated. Melting temperature of DNA was found to be increased up to 5 °C in the presence of the flavonoid indicating the stabilization of DNA double helix upon binding. CD and fluorescence anisotropic results have revealed the conformational changes in DNA upon binding to the flavonoid. The observed positive shift in peak potential and decreased peak current of the flavonoid in the presence of DNA further supported the intercalative mode of binding.