Interaction Of Bovine Serum Albumin With Flavonoids By Fluorescence And Ultraviolet Spectroscopy

Flavonoids are widely exist in natural and they have varied biological values due to their structure differences. Flavonoids could combine bovine serum albumin (BSA) and it operated in the body. The research on interaction between serum albumin and flavonoids is extremely significant to the acknowledgement of absorption, distribution and excretion. The interactions between the 5,7,4’-trihydroxy substituent flavonoids, the different number of substituent hydroxyls flavones on the B ring, the different number of substituent hydroxyls flavones on the A ring, flavonoids aglycones, glycosylation flavonoids and BSA were investigated by fluorescence spectroscopy and ultraviolet spectroscopy, the mechanism of the interaction between flavonoids and protein, it was binding constants, binding sites, thermodynamic binding parameters, and combination distance, as well as the impact on the protein conformational change caused by flavonoids. These findings were of great significance to biochemistry, pharmaceutical science, and clinical medicine.1. The interaction between apigenin, naringenin, genistein, galangin, kaempferol, quercetin a, myricetin,4’5-dihydroxyflavone, scutellarein, naringin, baicalein, baicalin and BSA were investigated through fluorescence spectroscopy. Experimental results showed that the flavonoids could quench BSA fluorescence and the quenching mechanism of them were static quenching. The binding constants of flavonoids and BSA were 12.69% 0.134% 0.301% 4.446.18.58% 1.550.2.417% 22.60% 11.87% 0.123% 8.851 and 0.577×106L-mor-1, the binding site were all about 1.2. The conformational change of protein was investigated before and after it’s interaction with the flavonoids using synchronous fuorescence and ultraviolet spectroscopy. The results showed that the hydrophobic nature of the micro-environment where tryptophan residues resided, as well as the secondary structure of protein changed after the combination of proteins, which further indicated the existence of the interaction between the flavonoids and BSA. The combination distance r were 2.71、1.83、2.32、2.61、2.71、2.92、2.23、2.74、 2.66、2.97、2.53 and 2.62nm, all less than 7nm, which indicated that the flavonoids molecule could fill in the BSA.3. The results indicated that hydrogenation on C ring could lower the affinity to BSA, while B ring connected to C-2 position could enhance the affinity to BSA. The hydroxyl connected to C-41 position could enhance the affinity to BSA. The hydroxyl connected to C-3’ or C-5’position could reduce the affinity to BSA. The more hydroxyls numbers on A ring, the less binding constants to BSA. The glycosylation flavonoids could reduce the affinity to BSA.