Voltammetric and Spectrophotometric Studies on DNA Interacting with Daunorubicin and its Amidino Derivatives

Daunorubicin (DAU) is one of the anticancer drugs widely applied in therapy although it reveals high toxicity. As a result of the search for new derivatives of anthracyclines with better biological properties, amidino antracyclines were invented. They contain in the daunosamine moiety an amidine group, –N=CR–NR1R2 where −NR1R2 is the rest of the cyclic secondary amine, instead of the −NH2 group. DAU and its two formamidino derivatives, the one containing the rest of the morpholine in the formamidine group (DAU‐Fmor) and the other one containing the rest of the hexamethyleneimine (DAU‐Fhex) were selected for voltammetric and spectrophotometric investigation of their interactions with DNA. These interactions were investigated by monitoring the changes in the UV/Vis absorption spectra of the anthracyclines interacting with oligonucleotides in the solution, as well as by monitoring the changes in electrochemical properties of oligonucleotides interacting with anthracyclines on the surface of screen‐printed graphite electrodes (SPEs) using square wave voltammetry (SWV). The obtained results indicate that interactions between DNA and anthracyclines depend mainly on two factors: the DNA sequence and the detailed structure of the anthracycline. As a result of these interactions, the anthracycline absorbance and the oxidation current of both, guanine and adenine change. The relations between these changes and the structure of the investigated anthracyclines are discussed.