Study on Interactions of Phenolic Acid-Like Drug Candidates with Bovine Serum Albumin by Capillary Electrophoresis and Fluorescence Spectroscopy

The interactions of the phenolic acids cinnamic acid (CNA), ferulic acid (FA), caffeic acid (CA) and chlorogenic acid (CLA) with bovine serum albumin (BSA) were investigated and compared using affinity capillary electrophoresis (ACE) and the fluorescence quenching methods. ACE gives binding constants (K _b) and thermodynamic parameters. The thermodynamic parameters show that each of four phenolic acids bind to BSA mainly by hydrogen bonds, electrostatic and hydrophobic interactions. The fluorescence quenching method provided quenching constant K _sv, binding site number n and K _b. The fluorescence results indicate that BSA fluorescence quenching is mainly a static quenching process. The binding constants (K _b) of CNA, FA, CA and CLA were from 2.52×10⁴ to 7.90×10⁴ L⋅mol⁻¹ from ACE experiments and 1.19×10⁴ to 5.21×10⁴ L⋅mol⁻¹ from fluorescence, their increase corresponded to the increase in the number of hydroxyl groups. These results imply that molecular structure and the number of hydroxyl groups of phenolic acids play act key roles in the affinity of natural phenolic acids towards BSA.