A fluorescence spectroscopic study of the interaction between Glipizide and bovine serum albumin and its analytical application

The interaction between Glipizide and bovine serum albumin (BSA), as well as the effect of some metal ions (Zn2+, Cu2+, Mn2+, Mg2+, Ni2+, V5+, Cr6+, Mo6+) on the BSA–Glipizide system were investigated at different temperatures by fluorescence spectroscopy. Results showed that Glipizide could quench the intrinsic fluorescence of BSA, and the quenching mechanism was a dynamic quenching process. The hydrophobic force played an important role on the conjugation reaction between BSA and Glipizide. The binding constants (Ka) were 1.45×104, 3.09×104, 4.51×104 L/mol at 293, 303 and 310 K, respectively, and the number of binding site (n) in the binary system was approximate to 1. The binding distance (r) was about 2.80 nm and the primary binding for Glipizide was located at the structure domain II A of BSA. The synchronous fluorescence spectra and CD spectra revealed that the microenvironment and the conformation of BSA were changed during the binding reaction. A new method of using BSA as probe to determine the content of Glipizide by fluorescence spectroscopy was established, and it was applied to analysis of Glipizide in tablets with a satisfying result. -- Highlights: • Glipizide could quench the intrinsic fluorescence of BSA strongly. • Hydrophobic force played an important role on the conjugation reaction. • The order of magnitude of binding constants (Ka) was 104. • Synchronous spectra revealed that the conformation of BSA was changed. • CD spectra revealed that the conformation of BSA was also changed