Abstract: With the aim of providing an experimental basis for extensive applications of protocatechuic aldehyde (PCA) and ferulic acid (FA) in the field of foods, the interactions and binding capacity of PCA and FA with bovine serum albumin (BSA) were investigated by spectroscopic and molecular docking techniques to uncover the underlying interaction mechanism. The results revealed that PCA and FA spontaneously bound to the active site of BSA by hydrogen bonds and van der Waals force with ΔG < 0. The binding capacity of PCA was much stronger than that of FA. A single binding site was observed for both PCA and FA, which was in the hydrophobic cavity between Domain IIA and Domain IIIA near Trp213 residue, thereby leading to static quenching of the endogenous fluorescence of BSA. The binding constant of PCA to BSA was greater than that of FA at 310 K (9.005 × 105 L/mol versus 2.553 × 105 L/mol). Meanwhile, the molecular docking results corroborated that PCA was closer to the Trp213 residue of BSA than FA (0.512 nm versus 0.518 nm). Therefore, PCA may more easily combine with BSA due to its higher polarity.

Key words: protocatechuic aldehyde; ferulic acid; bovine serum albumin; spectroscopy; molecular docking