Binding Studies of Two Double Rollovers Cycloplatinated Compounds and Bovine Serum Albumin by Fluorescence Spectroscopy

Platinum-containing compounds are among organometallic compounds that are considered promising drug candidates for cancer therapy. They have an important role in the treatment of several solid tumors. The interactions of small molecule drugs with serum albumin affect the pharmacokinetics of these therapeutic agents. In this study, the binding characteristics of two novel platinum complexes, named C1 and C2, and bovine serum albumin (BSA) were investigated by fluorescence and UV-visible spectroscopies. The results showed that these compounds diminished the fluorescence emission intensity of BSA through ground state quenching mechanisms. The apparent binding constant (Kb) values for the association of these compounds and BSA were in the range of 103-104 M-1, showing their moderate affinity to BSA. The Kb and the numbers of binding sites of BSA-complexes were increased by the elevation of temperature indicating that binding pockets were more accessible to these compounds at higher temperatures. Thermodynamic parameters showed that hydrophobic interactions are involved in C1-BSA complex formation and the interaction of C2 with BSA is through van der Waals interactions and hydrogen bonds.