Exploring the binding interaction of 1,4-naphthoquinone derivative–human serum albumin complex by biophysics and molecular simulation

A set of 1,4-naphthoquinone (1,4-NQ) derivatives possesses various pharmaceutical activities. Among them, a synthetic 2-(4-methoxyanilino)naphthalene-1,4-dione (MN) is found to be non-cytotoxic to the normal MRC-5 cells and prevent neuronal SH-SY5Y cell damage. To explore the underlying interaction mechanism of MN in the circulatory system, in silico and multi-spectroscopic techniques were employed to investigate the complex of human serum albumin (HSA) and MN. The interaction between HSA and MN exhibited static fluorescence with a potential dynamic mechanism, as K_sv×10⁵ (M^-1) decreased with increasing temperatures. Thermodynamic parameters and molecular dynamics (MD) simulations indicated a stable and spontaneous binding process driven by hydrophobic interactions and endothermic characteristics. Both circular dichroism (CD) and Fourier transform infrared (FT-IR) spectroscopy analyses revealed that MN induced conformational changes in HSA, affecting α-helix, β-turn, β-sheet, and random coil components, thereby altering the secondary structure of HSA. Competitive binding and molecular docking showed that MN preferentially binds to subdomain IIA in site I of HSA with the lowest binding affinity (‒7.15 kcal/mol), though it also has some affinities for subdomains IB and IIIA in site III and II, respectively. Additionally, the esterase activity of HSA showed no significant changes in the presence of MN. Understanding the binding interaction between MN and HSA provides valuable insights for further investigating the pharmacodynamic mechanism of MN and its potential applications in the area of medicinal chemistry.