Electrochemical studies on the interaction of an antibacterial drug nitrofurantoin with DNA

The electrochemical reduction of an antibacterial drug nitrofurantoin (NTF) at hanging mercury dropping electrode (HMDE) has been studied using techniques. NTF shows one irreversible reduction peak at 1.192 V in Britton-Robinson (BR) buffer of pH 7.1, ionic strength 0.2 mol/dm(3). Cyclic voltammetry (CV), differential pulse voltammetry (DPV) as well as UV/Vis spectroscopy were employed to probe the interaction between NTF and calf thymus DNA. From electrochemical data, the binding constant and binding ratio between DNA and drug was calculated to be 8.22 (+/- 0.05) x 10(6) M-1 and 1:3, respectively. Through chronocoulometry experiments, the diffusion coefficients were found as 1.10 (+/- 0.03) x 10(-6) cm(2) s(-1) for NTF and 3.67 (+/- 0.03) x 10(-8) cm(2) s(-1) NTF-DNA. Based on electrochemical and spectroscopic results, we concluded that the mode of binding of NTF-DNA was through intercalative binding. The calibration graph for the determination of DNA was obtained by the decrease in the DPV peak current of NTF in the presence of DNA. (C) 2011 Elsevier B.V. All rights reserved.