Interactions of cephalexin with bovine serum albumin: displacement reaction and molecular docking

The drug-plasma protein interaction is a fundamental issue in guessing and checking the serious drug side effects related with other drugs. The purpose of this research was to study the interaction of cephalexin with bovine serum albumin (BSA) and displacement reaction using site probes. The interaction mechanism concerning cephalexin (CPL) with BSA was investigated using various spectroscopic methods and molecular modeling method. The binding sites number, n, apparent binding constant, K, and thermodynamic parameters, ΔG⁰, ΔH⁰, and ΔS⁰ were considered at different temperatures. To evaluate the experimental results, molecular docking modeling was calculated. The distance, r=1.156 nm between BSA and CPL were found in accordance with the Forster theory of non-radiation energy transfer (FRET) indicating energy transfer occurs between BSA and CPL. According to the binding parameters and ΔG⁰= negative values and ΔS⁰= 28.275 j mol^-1K^-1, a static quenching process is effective in the CPL-BSA interaction spontaneously. ΔG⁰ for the CPL-BSA complex obtained from the docking simulation is -28.99 kj mol^-1, which is close to experimental ΔG of binding, -21.349 kj mol^-1 that indicates a good agreement between the results of docking methods and experimental data. The outcomes of spectroscopic methods revealed that the conformation of BSA changed during drug-BSA interaction. The results of FRET propose that CPL quenches the fluorescence of BSA by static quenching and FRET. The displacement study showed that phenylbutazon and ketoprofen displaced CPL, indicating that its binding site on albumin is site I and Gentamicin cannot be displaced from the binding site of CPL. All results of molecular docking method agreed with the results of experimental data.