Studies on the interaction of salicylic acid and its monohydroxy substituted derivatives with bovine serum albumin

Salicylic acid and its monohydroxy substituted derivatives are usually used as food additives. They can interact with bovine serum albumin (BSA) through π-π stacking, the monohydroxy substitutions can hinder the interactions through steric effects. In this paper, we systematically studied the interactions between BSA and salicylic acid and its monohydroxy substituted derivatives under simulative physiological conditions by diverse spectroscopic methods and molecular docking studies. The spectroscopic studies showed that the intrinsic fluorescence of BSA could be quenched by salicylic acid and its derivatives. The quenching mechanism is a combination of static and dynamic quenching. Furthermore, the molecular docking simulation revealed the binding sites (near the Trp-213 in the BSA) and the distance (2.1 nm, 2.9 nm, 2.0 nm, 2.7 nm and 3.3 nm, respectively) between ligand and protein, which is in good agreement with the calculated results of the energy transfer process. Our research may provide guidance for understanding the interactions between serum albumin and salicylic acid food additives.