The Fluorescence Spectroscopic Studies on the Interaction of Diltiazem Hydrochloride with Bovine Serum Albumin

Aim: To explore the interaction of the diltiazem hydrochloride (DTZ) with bovine serum albumin (BSA).

Methodology: Fluorescence and UV-Vis spectroscopic techniques were used to study the interaction between diltiazem hydrochloride (DTZ) and BSA. DTZ is a nondihydropyridine calcium channel blocker used in the treatment of many kinds of diseases. The Stern-Volmer quenching constant (Ksv), the quenching rate constant of the bimolecular reaction (Kq), the binding constant (Ka), and a number of binding sites (n) of DTZ with BSA were evaluated.

Results: The results revealed that DTZ quenches the fluorescence intensity of BSA through a static quenching process. The values of ΔS and ΔH indicated that hydrophobic bond interactions played major roles in the binding process and contributed to the stability of the DTZ-BSA complex. Based on the Förster’s theory of non-radiation energy transfer, the distance between donor (BSA) and acceptor (DTZ) was less than 7 nm, which indicated that energy transfer from BSA to DTZ occurs with high probability.