Review: electrochemical studies on some metal complexes having anti-cancer activities

Cancer is a leading cause of death worldwide. Since the discovery of cisplatin, a platinum-based anti-cancer metallodrug, research on metal-based compounds and complexes as potential anti-cancer agents has gained importance in modern medical and chemical sciences. Electrochemical techniques provide useful complements to other analytical methods of analysis such as UV–vis and fluorescence spectroscopy. Since the redox active metal complexes are not amenable to spectroscopic techniques either due to weak absorption bands or overlap of electronic transitions with those of DNA, they can potentially be studied via electrochemical techniques. Due to the resemblance between the electrochemical and biological redox reactions, the application of electrochemical measurements of metal-based anti-cancer drugs is a highly sensitive method. Cyclic voltammetry is a versatile technique to investigate redox activities during drug–DNA interactions. Variations in peak potentials and peak currents of a cyclic voltammogram during a redox reaction resulting from intercalation or electrostatic interactions can be used to determine equilibrium constants (K) and the number of base pair sites. This review is focused on some electrochemical studies of potential metal-based anti-cancer drug candidate−DNA interactions and the correlation between binding studies and anti-cancer activities.