Investigation of Intermolecular Interaction Between 4-Ethyl Phenyl Sulfate and Human Serum Albumin Using Spectroscopic Techniques and Molecular Docking Studies

Abstract

4-Ethyl phenyl sulfate (4-EPS), a gut microbiota-derived metabolite, is identified in ailments like chronic kidney disease (CKD) and numerous neurodegenerative conditions like autism spectrum disorders (ASD). This study is a novel attempt to comprehend the interaction of 4-ethyl phenyl sulfate (4-EPS) with human serum albumin (HSA). This interaction was examined using spectroscopic techniques like circular dichroism (CD), Fourier transform infrared (FTIR), UV–vis absorption, fluorescence spectroscopy, and molecular docking studies. The conformation investigation through FTIR and CD confirmed the alteration in the secondary structure of HSA due to the binding of 4-EPS. Fluorescence spectroscopy revealed the formation of a complex between HSA and 4-EPS upon interaction via static quenching. The spontaneity of the binding process was indicated by the negative ΔG value. Absorption spectroscopy demonstrated that in the presence of 4-EPS (2–48 μM), the absorbance of HSA progressively declined as a result of the formation of the 4-EPS–HSA complex. Contact angle measurements showed the involvement of hydrophobic interactions between HSA and 4-EPS. Molecular modeling was performed, followed by optimization using the DFT approach. Molecular docking study revealed moderate binding between the metabolite and HSA. It was further confirmed that hydrophobic interaction and hydrogen bonds were the main forces responsible for stabilizing the 4-EPS–HSA complex.