Characterizing the binding interaction of fungicide boscalid with bovine serum albumin (BSA): A spectroscopic study in combination with molecular docking approach

Boscalid, a carboxamide fungicide, is used in the treatment of grey mould and powdery mildew, widely applied to a variety of crops and fruits such as rice, wheat, grapes and pears. It will become a potential risk for health due to its widely application and residue in crops and fruits. In this study, the binding interaction between boscalid and bovine serum albumin (BSA) was characterized using steady-state fluorescence spectroscopy, ultraviolet spectroscopy (UV), synchronous fluorescence spectroscopy, 3D fluorescence spectroscopy, Fourier transform infrared spectroscopy (FT-IR) and molecular docking to ascertain the store, transport and distribution of boscalid in vivo. The experimental results indicated that the fluorescence of BSA was quenched due to the forming the static boscalid-BSA complex with the binding constant of 4.57 x 10(3) M-1 at 298 K and boscalid bound on the subdomain III A (site II) of BSA through van der Waals force and hydrogen bonding interaction. The binding process of boscalid with BSA was spontaneous and enthalpy-driven process based on Delta G(0) < 0 and vertical bar Delta H-0 vertical bar > T vertical bar Delta S-0 vertical bar over the studied temperature range. Meanwhile, the obvious change in the conformation of boscalid was observed while the slight change in the conformation of BSA when binding boscalid to the BSA, implying that the flexibility of boscalid contributes to increasing the stability of the boscalid-BSA complex.