Structure-affinity relationship of bovine serum albumin with dietary flavonoids with different C-ring substituents in the presence of Fe super(3+ ion)

• Published in: Food research international Vol. 44; no. 9; pp. 2861 - 2867
• Main Authors: Zhang, Yuping, Shi, Shuyun, Sun, Xiaorui, Huang, Kelong, Chen, Xiaoqin, Peng, Mijun
• Format: Journal Article
• Language: English
• Published: 01.11.2011
• Subjects: Affinity; Binding; Binding energy; Bonding; Flavonoids; Quenching; Serum albumin; Tantalum
• ISSN: 0963-9969
• DOI: 10.1016/j.foodres.2011.06.045

The relationship of four dietary flavonoids, quercein (QU), luteolin (LU), taxifolin (TA) and (+)-catechin (CA), with different C-ring substituents binding with bovine serum albumin (BSA) have been investigated in the absence and presence of Fe super(3+ by means of spectroscopic methods. The quenching constant (K) sub(S)V), binding constant (K sub(a), binding site number (n) and spatial-distance (r) of flavonoids with BSA were calculated. The results indicated that hydroxyl group at 3-position and C2-C3 double bond affected the binding affinities between flavonoids and BSA. The values of the binding affinities were in the order: QU CA TA LU. The presence of Fe) super(3)+ affected the interactions between flavonoids and BSA significantly, and the influence was distinct for the flavonoids with different C-ring structures. The binding affinities of QU, LU and CA for BSA were increased about 0.85%, 41.3% and 56.8% in the presence of Fe super(3+, probably because of the formation of QU-Fe) super(3)+-BSA complex, Fe super(3+-LU complex and the conformational change of BSA induced by Fe) super(3)+, respectively. The binding affinities of TA for BSA were decreased about 20.7%, mainly because of the existence of competitive binding between TA and Fe super(3+ with BSA. However, the quenching mechanism for QU, LU, TA and CA to BSA were based on static quenching combined with non-radiative energy transfer irrespective of the absence or presence of Fe) super(3)+ ion.