Spectroscopic and molecular modeling studies of the interaction between 4'-O-(α-L-oleandrosyl)daunorubicin and human serum albumin and its analytical application.

4'-O-(α-L-oleandrosyl)daunorubicin (ODNR) is a disaccharide analogue of daunorubicin with potent antitumor activity against leukemia cell line K562 cells and colon cancer cell line SW620 cells. In this paper, the binding interaction of ODNR with human serum albumin (HSA) was investigated under simulative physiological conditions by fluorescence spectroscopy in combination with UV absorption spectroscopy and molecular modeling method. A strong fluorescence quenching reaction of ODNR to HSA was observed and the quenching mechanism was suggested as static quenching according to the Stern-Volmer equation. The binding constants (K) at different temperatures as well as thermodynamic parameters, enthalpy change (ΔH) and entropy change (ΔS), were calculated according to relevant fluorescent data and Van't Hoff equation. The hydrophobic interaction was a predominant intermolecular force in order to stabilize the complex, which was in agreement with the results of molecular modeling study. In addition, the effects of other ions on the binding constants were also studied. Moreover, the synchronous fluorescence technique was successfully employed to determine the total proteins in serum, urine and saliva samples at room temperature under the optimum conditions with a wide linear range and satisfactory results.