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Structural Relationship and Binding Mechanisms of Five Flavonoids with Bovine Serum Albumin
Key Laboratory of Modern Chinese Medicines (China Pharmaceutical University), Ministry of Education, Nanjing 210009, China
Department of Pharmacognosy, College of Pharmacy, 3rd Military Medical University, Chongqing, China
* Author to whom correspondence should be addressed.
Received: 9 October 2010; in revised form: 1 December 2010 / Accepted: 6 December 2010 / Published: 9 December 2010
Abstract: Flavonoids are structurally diverse and the most ubiquitous groups of dietary polyphenols distributed in various fruits and vegetables. In this study, the interaction between five flavonoids, namely formononetin-7-O-β-D-glucoside, calycosin- 7-O-β-D-glucoside, calycosin, rutin, and quercetin, and bovine serum albumin (BSA) was investigated by fluorescence and UV-vis absorbance spectroscopy. In the discussion, it was proved that the fluorescence quenching of BSA by flavonoids was a result of the formation of a flavonoid-BSA complex. Fluorescence quenching constants were determined using the Stern-Volmer and Lineweaver-Burk equations to provide a measure of the binding affinity between the flavonoids and BSA. The binding constants ranked in the order quercetin > rutin > calycosin > calycosin-7-O-β-D-glucoside ≈ formononetin-7-O-β-D-glucoside. The results of thermodynamic parameters ΔG, ΔH, and ΔS at different temperatures indicated that the hydrophobic interaction played a major role in flavonoid-BSA association. The distance r between BSA and acceptor flavonoids was also obtained according to Förster’s theory of non-radiative energy transfer.
Keywords: flavonoids; bovine serum albumin; fluorescence quenching; binding mechanism
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Liu, E.-H.; Qi, L.-W.; Li, P. Structural Relationship and Binding Mechanisms of Five Flavonoids with Bovine Serum Albumin. Molecules 2010, 15, 9092-9103.
Liu E-H, Qi L-W, Li P. Structural Relationship and Binding Mechanisms of Five Flavonoids with Bovine Serum Albumin. Molecules. 2010; 15(12):9092-9103.
Liu, E-Hu; Qi, Lian-Wen; Li, Ping. 2010. "Structural Relationship and Binding Mechanisms of Five Flavonoids with Bovine Serum Albumin." Molecules 15, no. 12: 9092-9103.