Spectroscopic and molecular docking studies of binding interaction of gefitinib, lapatinib and sunitinib with bovine serum albumin (BSA)

•The intrinsic fluorescence of BSA quenched by three TKIs due to forming stable TKIs–BSA•Lapatinib was located on site II (m) of BSA while gefitinib and sunitinib were bound on site I of BSA.•The main interaction forces were van der Waals and hydrogen bonding interactions.•There was slight change of the secondary structure of BSA due to binding to three TKIs.

The binding interactions of three kinds of tyrosine kinase inhibitors (TKIs), such as gefitinib, lapatinib and sunitinib, with bovine serum albumin (BSA) were studied using ultraviolet spectrophotometry, fluorescence spectroscopy, circular dichroism (CD), Fourier transform infrared spectroscopy (FT-IR) and molecular docking methods. The experimental results showed that the intrinsic fluorescence quenching of BSA induced by the three TKIs resulted from the formation of stable TKIs–BSA complexes through the binding interaction of TKIs with BSA. The stoichiometry of three stable TKIs–BSA complexes was 1:1 and the binding constants (Kb) of the three TKIs–BSA complexes were in the order of 104 M− 1 at 310 K, indicating that there was a strong binding interaction of the three TKIs with BSA. Based on the analysis of the signs and magnitudes of the free energy change (ΔG0), enthalpic change (ΔH0) and entropic change (ΔS0) in the binding process, it can be deduced that the binding process of the three TKIs with BSA was spontaneous and enthalpy-driven process, and the main interaction forces between the three TKIs and BSA were van der Waals force and hydrogen bonding interaction. Moreover, from the results of CD, FT-IR and molecular docking, it can be concluded that there was a significant difference between the three TKIs in the binding site on BSA, lapatinib was located on site II (m) of BSA while gefitinib and sunitinib were bound on site I of BSA, and there were some changes in the BSA conformation when binding three TKIs to BSA but BSA still retains its secondary structure α-helicity.

Graphical abstractIt has been confirmed that three TKIs interact with BSA via van der Waals and hydrogen bonding interactions through spectroscopic methods (such as UV–vis absorption spectroscopy, fluorescence emission spectroscopy) and molecular docking. It is important to note that the binding sites for different TKIs on BSA were different. Lapatinib was located on site II (m) of BSA while gefitinib and sunitinib were bound on site I of BSA.Figure optionsDownload full-size imageDownload as PowerPoint slide