CHARACTERIZATION OF THE INTERACTIONS BETWEEN NATURAL FLAVONOID COMPOUNDS AND BOVINE SERUM ALBUMIN BY CAPILLARY ELECTROPHORESIS AND FLUORESCENCE METHOD

Abstract

The interactions of three flavonoid compounds isolated from natural products: Puerarin, (−)-Epicatechin, (−)-Epigallocatechin gallate with bovine serum albumin (BSA) are investigated by two methods: affinity capillary electrophoresis (ACE) and fluorescence quenching method. ACE gives binding constants (K_b) and thermodynamic parameters. The thermodynamic parameters indicate that van der Waals interactions and hydrogen bond played important roles. The result also implies that in spite of the relatively small difference in the chemical structures, large differences are observed in their binding capacity. The fluorescence quenching method gains quenching constant K_sv, binding site number n and K_b. The fluorescence results indicate that BSA fluorescence quenching mechanism is mainly a static quenching process. The results of the two methods show the flavonoids had a fairly strong interaction with BSA. The K_b obtained from ACE is similar with that obtained from the fluorescence method. Our work might give an insight on the high throughput screening active components in natural products.

Keywords:

• ACE
• BSA
• flavonoids
• fluorescence quenching
• interaction

ACKNOWLEDGMENTS

This work was supported by National Basic Research Program of China (2007CB714505). The authors have declared no conflict of interest.

Notes

^a X and Y in the regression equations were at µg/ml and AU corresponding to the concentration and peak area, respectively.

^a Reported reference values using fluorescence method.

^A K _b and ^F K _b are binding constants obtained by ACE and Fluorescence methods, respectively.