The simultaneous carrier ability of natural antioxidant of astaxanthin and chemotherapeutic drug of 5-fluorouracil by whey protein of β-lactoglobulin: spectroscopic and molecular docking study.

In the present study, the simultaneous carrier ability of natural antioxidant of astaxanthin (ATX) and chemotherapeutic drug of 5-fluorouracil (5-FU) by whey protein of β-lactoglobulin (β-LG) using various spectroscopic techniques (UV-visible, fluorescence, circular dichroism (CD) and dynamic light scattering) in combination with molecular docking were investigated (at room and physiological temperatures). According to the fluorescence quenching tests, the binding parameters between drug and ATX with protein showed that the number of their binding sites was the same in the single and competitive states. Molecular docking results have showed completely consistent with the fluorescence data that presented the independent binding sites for 5-FU and ATX on β-LG. Also, analysis of Far-UV-CD showed that the simultaneous binding of the drugs to the protein partially enhances its stability, which is associated with the decreasing in β-sheet structure and increasing in α-helix. According to the Zeta potential measurements in the presence of different concentrations of the drugs, they have stronger binding to the protein at lower concentrations. Therefore, given the remarkable features of β-LG, including the ability to interact simultaneously with the natural compound of ATX and the antitumor drug of 5-FU, this study could provide useful information for the development and improvement of new protein carrier systems with synergism potency. Communicated by Ramaswamy H. Sarma.