Structural and molecular aspects of flavonoids as ligands for serum transferrin

Human serum transferrin (HST) acts as a carrier for Fe3+ and other ions. Binding of flavonoids to HST produces changes in the protein structure with direct implication on iron delivery into cells. We investigate the binding mechanism and affinity towards HST of three flavonoids: rutin, luteolin, and apigenin by different techniques: UV-Vis, fluorescence, fluorescence resonance energy transfer (FRET) combined with molecular docking. UV-Vis results indicate an interaction between flavonoids and HST. It was observed that HST fluorescence was quenched by these three flavonoids via a static process. All the interactions were moderate and the main driving forces are hydrophobic (Delta H > 0 and Delta S > 0) for rutin and luteolin binding or electrostatic (Delta H < 0 and Delta S > 0) for apigenin binding. FRET and molecular docking studies confirm the fluorescence static quenching mechanism by flavonoid binding. The binding of all three flavonoids increases HST stability. These results present the potential use of HST in target-oriented delivery of flavonoids and possibly other drugs into cells. (C) 2021 Elsevier B.V. All rights reserved.

Automated summary

The study found that the binding of three flavonoids to HST can affect HST stability through different interaction forces, such as hydrophobic for rutin and luteolin and electrostatic for apigenin. The results suggest the potential use of HST for targeted delivery of flavonoids and other drugs into cells.