Abstract: The binding of drugs with human serum albumin(HSA) is a crucial factor influencing the distribution and bioactivity of drugs in the body. To understand the action mechanisms between gallic acid(GA, 3,4,5-trihydroxy- benzoic acid) and HSA, the binding of GA with HSA was investigated by a combined experimental and computational approach. The fluorescence properties of HSA and the binding parameters of GA collectively indicate that the binding is characterized by static quenching mechanism at one high affinity binding site. According to the estimated molecular distance between the donor(HSA) and the acceptor(GA), the binding is related to the fluorescence resonance energy transfer. As indicated by the thermodynamic parameters, hydrophobic interaction plays a major role in the GA-HSA complex. Further, the experimental results reveal that GA is bound in the large hydrophobic cavity of subdomain IIA in the site I of HSA, which is well approved by molecular docking.

Key words: Gallic acid, Human serum albumin, Fluorescence quenching, Molecular modeling