Investigation of the interaction between flavonoids and human serum albumin

The interactions of flavonoids, including quercetin, rutin, hyperin and baicalin, with human serum albumin (HSA) were studied. Fluorescence emission spectra of HSA in the presence of the investigated compounds, recorded at the excitation and emission wavelength of 280 and 290–500 nm, respectively, clearly showed that these compounds quenched the fluorescence of HSA. The binding constants and the number of binding sites of the flavonoids with HSA were obtained by three different calculation methods and the results obtained by these methods were compared. The effects of various metal ions on the binding constants of these flavonoids with HSA were also studied. Based on the mechanism of the Fo¨rster energy transference, the energy transfer efficiency between the acceptors and HSA were found. The relationship between the structure characteristics of these compounds and binding properties of the flavonoids and HSA was explored. q 2004 Elsevier B.V. All rights reserved