Fluorescence studies on the interactions of barbaloin with bovine serum albumin

Abstract

The fluorescence quenching reactions of barbaloin with bovine serum albumin (BSA) in pH 7.20 Tris-HCl buffer solution were studied. The quenching mechanism of BSA by barbaloin was interpreted using the Stern-Volmer (S-V) mechanism. The binding constant K values were 2.78×105 (293 K), 1.87×105 (310 K), 1.25×105 (318 K), and the number of binding sites (n) were 1.18, 1.14, and 1.09, respectively. In addition, the thermodynamic functions enthalpy (ΔH°) and entropy (ΔS°) for the reaction were also calculated according to Vant's Hoff equation were -23.7 kJ/mol and 23.6 J/mol, respectively. Plausible explanations of the quenching mechanism are discussed on the basis of a hydrophobic interaction between barbaloin and BSA. © 2003 Pharmaceutical Society of Japan.