Comprehensive Insights into the Interactions of Two Emerging Bromophenolic DBPs with Human Serum Albumin by Multispectroscopy and Molecular Docking

Disinfection byproducts (DBPs) are of high concern due to their ubiquitous existence in disinfected drinking water and their potential adverse effects on human health. In this study, two bromophenolic DBPs 4-bromophenol (4-BrPh) and 2,4-dibromophenol (2,4-DiBrPh) were selected to investigate their binding interactions with human serum albumin (HSA) using spectroscopic techniques and a molecular docking method. The experimental results demonstrated that both of the DBPs could bind with HSA to form bromophenol-HSA complexes with the HSA secondary structure being changed, primarily relying on hydrogen bonding and van der Waals forces, but 2,4-DiBrPh showed a higher binding affinity. The binding constants of 4-BrPh-HSA and 2,4-DiBrPh-HSA were 2.66 x 10(3) and 1.83 x 10(4) M-1 at 310 K, respectively. Molecular docking results revealed the locations of the binding sites for bromophenols on HSA (locating in subdomain IB). In addition, the comparative toxicity of the two bromophenolic DBPs was evaluated with the mammalian cytotoxicity bioassay and the results showed that the LC50 values of 4-BrPh and 2,4-DiBrPh were 3.08 x 10(-5) and 1.09 x 10(-5) M, respectively. Notably, 2,4-DiBrPh with a higher binding affinity toward HSA also showed a significantly higher toxic potency than 4-BrPh.