Interpretation of the binding interaction between bupropion hydrochloride with human serum albumin: A collective spectroscopic and computational approach

Abstract Bupropion hydrochloride (BPH) an antidepressant and widely used to treat addiction of nicotine. The actual protein existing in blood plasma for the vehicle of exogenous and endogenous substances is human serum albumin i.e. HSA. The interaction of BPH with HSA was examined by molecular docking, multiple spectroscopy's such as fluorescence (emission, synchronous and three-dimensional), UV–vis (ultraviolet–visible), FT–IR (Fourier transform infrared) and CD (circular dichroism) at physiological pH 7.40 at 286, 296 and 306 K. BPH was particularly bind to HSA through forces called hydrogen bonds and vander Waals at site I (IIA) which was confirmed from negative values of thermodynamics calculated by van't Hoff equation and docking studies in addition to site marker analysis. This interaction was spontaneous and exothermic process. Secondary structure including conformation of HSA changes after interaction with BPH was revealed from CD and FT–IR (Fourier self-deconvolution to curve fitting), UV–vis, 3D and synchronous florescence techniques. Forster's theory (non–radiation energy transfer) was applied to calculate the distance from tryptophan of HSA to BPH. This interaction involves static quenching (Stern–Volmer and Modified Stern–Volmer equations) with larger binding constant values were in the range 105 confirming that strong interaction was exists between BPH and HSA. The interference of bio-active Mg2+, Cu2+, Zn2+, Ca2+ and Fe2+ metal ions on this interaction was also analysed.