Spectroscopic Study of the Interactions of Buflomedil to Serum Albumin and β-Cyclodextrin

The effects of buflomedil (BFM), a novel cerebrovascular medicine, on serum albumin and the feasibility of beta-cyclodextrin (beta-CD) acting as a controlled releaser for BFM were investigated by molecular spectroscopy methods, including fluorescence emission, UV-visible absorption, Fourier transform infrared (FT-IR), synchronous and three-dimensional fluorescence spectroscopies. The interaction of BFM with bovine serum albumin (BSA) was analyzed by fluorescence quenching and it was found that BFM had reacted with BSA in the ground state and had affected the secondary structure of BSA. The observed binding constant K (b), the number of binding sites n, the distance r between donor (BSA) and acceptor (BFM), the enthalpy change (Delta H (theta) ), Gibbs energy change (Delta G (theta) ) and entropy change (Delta S (theta) ) at different temperatures were calculated. The inclusion reaction between beta-CD and BFM was explored by the Lineweaver-Burk equation. The inclusion constants and the thermodynamic parameters were determined. The mechanism of the inclusion reaction was discussed and the controlled release characteristics of beta-CD to BFM were considered at the molecule level.