In vitro DNA binding studies of anticancer drug idarubicin using spectroscopic techniques

•The interaction antitumor drug, idarubicin, and DNA is investigated.•Several spectroscopic techniques are used in the study of interaction.•Fluorescence quenching mechanism of idarubicin and DNA is combined static and dynamic.•The interaction between idarubicin and DNA is intercalation mode.

The interaction between idarubicin and double stranded deoxyribonucleic acid (ds-DNA) was investigated by UV–VIS spectrophotometry, fluorescence and Raman spectroscopy techniques. The absorption spectra of idarubicin with ds-DNA showed a slight red shift and hypochromic effect. In the fluorescence experiments, emission peaks were decreased by adding ds-DNA. Using ethidium bromide (ETB) as a fluorescence probe, fluorescence quenching of the emission peak was observed in the ETB-DNA system when idarubicin was added. Moreover, similar results were obtained in Raman spectroscopy. Binding constants of idarubicin with ds-DNA were determined as 5.14 × 105 M−1 and 5.8 × 105 M−1 for UV–VIS spectrophotometry and fluorescence spectroscopy, respectively. The large binding constant indicated that idarubicin has a high affinity with ds-DNA. All the evidences indicated that the binding mode of idarubicin with DNA was an intercalative binding. Furthermore, quantitative determination of idarubicin in pharmaceutical formulation was done.