Ruthenium (II) complexes binding to human serum albumin and inducing apoptosis of tumor cells

The binding properties of two Ru(II) complexes [Ru(bpy)2(ox)]2 + (RBO) and [Ru(bpy)2(suc)]2 + (RBS) (bpy = 2, 2-bipyridine, ox = oxalate, and suc = succinate) to human serum albumin (HSA) have been studied by fluorescence, UV–vis absorption spectroscopy and circular dichroism (CD) spectroscopy. The fluorescence quenching mechanism was determined to be a static quenching procedure. The Stern–Volmer quenching constant Ksv and corresponding thermodynamic parameters ΔH, ΔS and ΔG were calculated. The number of binding site was about 1. The result of CD showed that the secondary structure of HSA molecules was changed in the presence of the Ru(II) complexes. Furthermore, the anticancer activities of the complexes were evaluated by using the MTT assay, the results indicated that the antiproliferative activity of RBS was higher than that of RBO, and RBS showed a significant antitumor activity through induction of apoptosis in A549 cells.