A multi-spectroscopic, molecular docking and molecular dynamics study on the binding between bovine serum albumin and ethyl-paraben/propyl-paraben

Parabens can cause endocrine-disrupting effects, hepatotoxicity and pulmonary toxicity in human. Serum albumin is crucial for transporting different exogenous and endogenous molecules. However, the transport mechanisms of parabens in body are not fully understood. In this study, ethyl-paraben (EtP) and propyl-paraben (PrP) were selected to investigate the interactions between parabens and bovine serum albumin (BSA) using multi-spectroscopy, molecular docking and molecular dynamics (MD) analysis. The spectroscopic results showed that EtP and PrP spontaneously occupied site I of BSA to form complexes. The quenching mechanism of BSA-PrP system was static quenching, whereas the quenching behavior of BSA-EtP system was a mixed quenching mechanism of dynamic and static quenching. The formation of BSA-EtP complex is mainly driven by hydrophobic interactions, while van der Waals and hydrogen bonding forces were predominant in BSA-PrP interaction. The results of three-dimensional (3D) and circular dichroism (CD) spectroscopy revealed that EtP and PrP caused alternations on the conformational structure of BSA. PrP exerted a more pronounced effect on BSA conformation. Meanwhile, EtP inhibited the esterase-like activity of BSA, while PrP increased the esterase-like activity of BSA. Molecular docking analysis showed some specific amino acid residues and π-electrons on the benzene ring of EtP/PrP were crucial for maintaining the stability of BSA-EtP/PrP complexes. The results of MD study further confirmed that PrP exerted more effects on the structure of BSA, which were consistent with the results of spectral and molecular docking analysis. This study will provide essential insights for understanding the transportation and distribution mechanisms of parabens in body.