Interaction studies of cannabidiol with human serum albumin by surface plasmon resonance, spectroscopy, and molecular docking

Abstract

The binding interaction of cannabidiol (CBD) and human serum albumin (HSA) under physiological blood pH conditions (pH 7.4) was conducted by surface plasmon resonance (SPR), fluorescence spectroscopy, UV-Visible spectrophotometry, and molecular docking. The responses from SPR measurement increased with the increase in CBD concentration until equilibrium was reached at the equilibrium dissociation constant (KD) of 9.8 × 10−4 M. The results from fluorescence and UV-Visible spectroscopy showed that CBD bound to HSA at one site in a spontaneous manner to form protein-CBD complexes. The quenching process involved both static and dynamic mechanisms while the static mechanism contributed predominantly to the binding between CBD and albumin. The binding constants estimated from the fluorescence studies were from 0.16 × 103 to 8.10 × 103 M−1, which were calculated at different temperature conditions using Stern-Volmer plots. The thermodynamic parameters demonstrated that the binding interaction was a spontaneous reaction as Gibbs free energy had negative values (ΔG = −12.57 to −23.20 kJ.mol−1). Positive ΔH and ΔS values (ΔH = 2.46 × 105 J.mol−1 and ΔS = 869.81 J.mol−1K−1) indicated that the hydrophobic force was the major binding interaction. Finally, confirmation of the type and extent of interaction was provided using UV-spectroscopy and molecular docking studies. The outcomes of this study are expected to serve as a platform to conduct future studies on binding interactions and toxicological research of CBD. Communicated by Ramaswamy H. Sarma