Effect of Cu and Al on the interaction of chlorogenic acid and caffeic acid with serum albumin.

Despite the phenolic acids' health benefits, their interactions with proteins are still unclear. In this study, the interactions of Bovine Serum Albumin (BSA) with chlorogenic acid (CHA), caffeic acid (CA), and their Al, Cu complexes were studied by using circular dichroism (CD) spectroscopy, fluorescence spectroscopy, and UV/Vis spectroscopy. It was found that esterification of carboxyl group of CA with quinic acid increased the binding affinities for BSA. After chelating with Cu and Al, both CHA and CA exhibited high binding affinities for BSA. CHA could form CHA-Cu and CHA-Al complex with Cu and Al. The result of CD spectroscopy demonstrated that the binding of CHA and Al with BSA contributed to the folding of BSA secondary structure. In addition, with the presence of CHA, binding with Al could also induce changes in BSA conformation. The binding sites of both CHA and CA were closed to Trp213.