Study on the interaction of an anthracycline disaccharide with DNA by spectroscopic techniques and molecular modeling.

This study was designed to examine the interaction of 4'-O-(a-L-Cladinosyl) daunorubicin (DNR-D5), a disaccharide anthracycline with calf thymus deoxyribonucleic acid (ctDNA) by UV/Vis in combination with fluorescence spectroscopy and molecular modeling techniques under physiological conditions (Britton-Robinson buffer solutions, pH = 7.4). By the analysis of UV/Vis spectrum, it was observed that upon binding to ctDNA the anthraquinone chromophore of DNR-D5 could slide into the base pairs. Moreover, the large binding constant indicated DNR-D5 had a high affinity with ctDNA. At the same time, fluorescence spectra suggested that the quenching mechanism of the interaction of DNR-D5 to ctDNA was a static quenching type. The binding constants between DNR-D5 and ctDNA were calculated based on fluorescence quenching data at different temperatures. The negative ∆G implied that the binding process was spontaneous, and negative ∆H and negative ΔS suggested that hydrogen bonding force most likely played a major role in the binding of DNR-D5 to ctDNA. Moreover, the results obtained from molecular docking corroborate the experimental results obtained from spectroscopic investigations.