Probing the interaction of ellagic acid with human serum albumin: A fluorescence spectroscopic study

Human serum albumin (HSA) is a principal plasma protein, carries the drug molecules to target sites in human body. Ellagic acid (EA) derived from ellagitannins plays an important role as a drug because of its unique pharmacological properties. The interactions between EA and HSA were studied by fluorescence spectroscopic techniques under similar to human physiologic conditions. The binding parameters have been evaluated by fluorescence quenching methods. The results proved the mechanism of fluorescence quenching of HSA while interacting with EA is due to the formation of EA - HSA complex formation. The thermodynamic parameters like Delta H and Delta S were calculated to be - 17.32 kJ/mol and 34.91 J/mol/K, respectively, which proves the involvement of weak interactive forces like hydrogen and hydrophobic bonds during the interaction. Molecular docking study shows hydrogen-bonding distance between EA and HSA molecule. The distance r between donor (HSA) and acceptor (EA) was obtained according to the Forster's theory of non-radiative energy transfer and found to be 1.96 nm. This study will give an insight on the evaluation of the drug stability during transport and releasing efficiency at the target site in human physiological conditions.