DNA/protein binding and anticancer activity of ruthenium (II) arene complexes based on quinoline dipyrrin

Arene ruthenium complexes [(eta(6)-arene)Ru(L)Cl] (eta(6)-arene = benzene, R1; p-cymene, R2) containing the chelating ligand (2-chloro-3-(di(1H-pyrrol-2-yl)methyl)quinoline) (L) have been synthesized and carefully characterized by various studies (H-1 and C-13 NMR, IR, ESI-MS, UV-vis). The structure of R1 has been verified by X-ray single crystal analyses. Binding of the complexes with calf thymus DNA (CT-DNA) has been investigated by absorption titration, ethidium bromide (EB) displacement and viscosity measurements. Experimental binding constants (5.1 x 10(4) M-1, R1; 5.7 x 10(4) M-1, R2) suggested appreciable bonding of the complexes with CT-DNA. Fluorescence, synchronous and 3D fluorescence spectroscopic studies showed that complexes strongly bind with bovine serum albumin. Intercalative interaction of the complexes with DNA has been further supported by DFT studies. Our studies have shown potential anticancer activity of both the complexes R1 and R2 against T cell lymphoma. Among these complexes R2 showed better anticancer activity relative to R1 (IC50, R1, 30 mu M and R2, 20 mu M).