Resveratrol, Genistein, and Curcumin Bind Bovine Serum Albumin

We report the complexation of bovine serum albumin (BSA) with resveratrol, genistein, and curcumin, at physiological conditions, using constant protein concentration and various polyphenol contents. FTIR, CD, and fluorescence spectroscopic methods were used to analyze the ligand binding mode, the binding constant, and the effects of complexation on BSA stability and conformation. Structural analysis showed that polyphenols bind BSA via hydrophilic and hydrophobic interactions with the number of bound polyphenol (n) being 1.30 for resveratrol-BSA, 1.30 for genisten-BSA, and 1.0 for curcumin-BSA. The polyphenol-BSA binding constants were KRes-BSA = 2.52(+/-0.5) x 10(4) M-1, KGen-BSA = 1.26(+/-0.3) x 10(4) M-1, and KCur-BSA = 3.33(+/-0.8) x 10(4) M-1. Polyphenol binding altered BSA conformation with a major reduction of alpha-helix and an increase in beta-sheet and turn structures, indicating a partial protein unfolding.