Biophysical Study on the Interaction between Eperisone Hydrochloride and Human Serum Albumin Using Spectroscopic, Calorimetric, and Molecular Docking Analyses

Eperisone hydrochloride (EH) is widely used as a muscle relaxant for patients with muscular contracture, low back pain, or spasticity. Human serum albumin (HSA) is a highly soluble negatively charged, endogenous and abundant plasma protein ascribed with the ligand binding and transport properties. The current study was undertaken to explore the interaction between EH and the serum transport protein, HSA. Study of the interaction between HSA and EH was carried by UV−vis, fluorescence quenching, circular dichroism (CD), Fourier transform infrared (FTIR) spectroscopy, Forster’s resonance energy transfer, isothermal titration calorimetry and differential scanning calorimetry. Tryptophan fluorescence intensity of HSA was strongly quenched by EH. The binding constants (Kb) were obtained by fluorescence quenching, and results show that the HSA–EH interaction revealed a static mode of quenching with binding constant Kb ≈ 104 reflecting high affinity of EH for HSA. The negative ΔG° value for binding indicated that...