Interaction of cinnamic acid and methyl cinnamate with bovine serum albumin: A thermodynamic approach

- Cinnamic acid and methyl cinnamate bound to bovine serum albumin.
- pH strongly influenced ligand-protein binding due to electrostatic forces.
- Methyl cinnamate-protein was more favorable than cinnamic acid-protein binding.
- Ligands had no effect on the surface tension of protein/air interfaces.

Cinnamic acid (CA) and methyl cinnamate (MC) have attracted interest of researchers because of their broad therapeutic functions. Here, we investigated the interaction of CA and MC with bovine serum albumin (BSA) at pH 3.5, 5.0, and 7.4 using fluorescence spectroscopy, differential scanning nanocalorimetry, and measurements of interfacial tension, size, and zeta potential. BSA formed a complex with the ligands with stoichiometry of approximately 1.0. At pH 7.4, CA-BSA complex formation was entropically driven. The interaction between MC and BSA was more favorable than with CA and was enthalpically driven under the same conditions. The pH played an important role in BSA conformation, which altered the manner in which it interacts with the ligands. Interestingly, both CA and MC had no effect on the surface tension of BSA/air interfaces. These data contribute to the knowledge of CA/MC-BSA interactions and provide important data for application in the food industry.