A spectroscopic study on the modulation of butylated hydroxyanisole-bovine serum albumin interaction by β-cyclodextrin: effects of coexistence and encapsulation

The effect of β-cyclodextrin (β-CD) coexistence and encapsulation on the interaction between butylated hydroxyanisole (BHA) and bovine serum albumin (BSA). The results of various spectral analyses, including fluorescence spectroscopy, three-dimensional (3D) fluorescence spectroscopy, Fourier transform infrared spectroscopy (FT-IR), and circular dichroism spectroscopy (CD), revealed that β-CD suppresses BHA-BSA binding through dual mechanisms, thereby mitigating BHA-induced conformational alterations in BSA. Specifically, upon formation of the BHA/β-CD inclusion complex, the binding affinity of BHA to BSA was significantly weakened, with the binding constant decreasing from 6.10 × 103 M−1 to 5.36 × 102 M−1. The thermodynamic analysis indicated that BHA to BSA binding is primarily driven by hydrophobic interactions. However, β-CD shifts this interaction to is a weakly entropy-driven or enthalpy-entropy compensation mechanism. Moreover, the coexistence and encapsulation of β-CD did not significantly affect BHA’s antioxidant capacity and esterase-like activity. The β-CD encapsulation protects BSA’s native conformation.