Electrochemical and spectroscopic studies of the interaction between the neuroleptic drug, gabapentin, and DNA

► The interaction of the neuroleptic drug, gabapentin, and DNA is investigated for the first time. ► Several analytical methods are used in the study of interaction which their results are comparable. ► The interaction between gabapentin and DNA occurs through electrostatic and groove binding modes. The interaction between gabapentin (GP), a neuroleptic drug, and calf-thymus DNA was investigated. Cyclic voltammetry and different spectroscopic methods (UV/vis spectrophotometry, spectroflourimetry and circular dichroism) were used to study the process. The oxidation current of GP was considerably decreased in the presence of calf-thymus DNA. The negative shift of the peak potential in cyclic voltammetry suggested an electrostatic interaction, while spectroscopic methods show minor groove binding as the predominant mode. The values of binding constants obtained from UV absorption, spectrofluorimetry and voltammetric measurements were in close agreement. Standard Gibbs free energy change, ΔG0, of the interaction was calculated to be −21.99kJmol−1 which indicated the spontaneity of the binding interaction. A hyperchromic effect in the maximum absorption band of DNA as well as quenching in fluorescence experiments were observed in the presence of GP.