Effect of the bile salt surfactant sodium taurodeoxycholate on the physicochemical properties of a mixed system of Galangin-Hemoglobin and Baicalein-Hemoglobin

A surfactant that can regulate interactions between drugs and proteins would be a material that is medicinally excipient and biomimetic that has great theoretical and practical significance. Thus, the interactions and binding mechanism of flavonoid isomers [galangin (Gal) and baicalein (Bai)] and hemoglobin (HB) under physiological conditions were studied using multispectral methods, dynamic light scattering (DLS), and antioxidant, antibacterial, and cytotoxicity assay techniques. Then, one bile salt biosurfactant [sodium taurodeoxycholate (NaTDC)] was added to explore the effects that it has on the interactions and functional properties of Gal-HB and Bai-HB systems. For Gal-HB and Bai-HB systems, the fluorescence quenching mechanism of flavonoids on HB was always a static quenching. Driven mainly by electrostatic forces, the conformation of HB became loose, and its secondary structure changed as a result of the presence of Gal or Bai. Three adjacent hydroxyl groups on the A-ring had an obvious binding interaction with protein, and thus, Bai had a stronger binding affinity with HB than Gal, and this has a greater influence on the secondary structure of HB than Gal. In the presence of NaTDC, the binding constants were significantly increased for both systems; also, the antioxidant character, stability, solubility, antibacterial properties, and cancer cell growth inhibition of flavonoids were improved to a certain extent. These findings help us understand the pharmacokinetics, pharmacodynamic function and mechanism of Gal and Bai at the molecular level and also lay the scientific foundation for the design of flavonoid-based foods and drugs.