The binding assessment with human serum albumin of novel six-coordinate Pt(IV) complexes, containing bidentate nitrogen donor/methyl ligands

Abstract

The interactions between platinum complexes and human serum albumin (HSA) play crucial roles in the distribution, metabolism, and activity of platinum-based anticancer drugs. Octahedral platinum (IV) complexes represent a significant class of anticancer agents that display molecular pharmacological properties different from cisplatin. In this study, the interaction between two Pt(IV) complexes with the general formula [Pt(X)2Me2 (tbu2bpy)], where tbu2bpy = 4,4′-ditert-butyl-2,2′-bipyridine, with two leaving groups of X = Cl (Com1) or Br (Com2), and HSA were investigated, using Ultraviolet-Visible (UV-Vis) spectroscopy, fluorescence spectroscopy, circular dichroism (CD) and molecular docking simulation. The spectroscopic and thermodynamic data revealed that the HSA/Pt(IV) complexes interactions were spontaneous process and Com2 demonstrated stronger interaction and binding constant in comparison with Com1. Also, the results suggest approximately similar structural alteration of HSA in the presence of these Pt complexes. Molecular docking revealed that both Pt(IV) complexes bind with HSA in subdomain IB, literally the same as each other. This study suggests that variation in the leaving group, displaying differing departure rate, has no significant contribution in denaturing prosperities of the Pt(IV) complexes against HSA.