Cationic Ru(II), Rh(III) and Ir(III) complexes containing cyclic pi-perimeter and 2-aminophenyl benzimidazole ligands: Synthesis, molecular structure, DNA and protein binding, cytotoxicity and anticancer activity

Synthesis, characterization, DNA and protein binding as well as anticancer activity of the organometallic complexes [(eta(6)-C6H6)RuCl(APBI)]Cl (1), [(eta(6)-p-MeC6H4Pri)RuCl(APBI)] Cl (2), [(eta(6)-C6Me6)RuCl(APBI)]Cl (3), [(eta(5)-C5Me5)RhCl(APBI)]Cl center dot H2O (4) and [(eta(5)-C5Me5)IrCl(APBI)]Cl center dot H2O (5) containing 2-aminophenyl benzimidazole (APBI) have been described. The complexes 1-5 exhibited strong DNA, protein binding and anticancer activity against cervical cancer (SiHa) cell line. Their binding with calf thymus DNA (CT-DNA) and bovine serum albumin (BSA) have been examined by absorption and emission spectral studies. Strong interactions between complexes and CT-DNA have been affirmed by absorption spectral and EthBr displacement studies, while interaction with BSA via static quenching explored by fluorescence titration, synchronous and 3D fluorescence spectroscopy. The interactions between 1-5 and DNA has also been scrutinized by H-1 NMR spectral studies using guanosine as a model for DNA. These results have been supported by DFT calculations and molecular docking studies. Cytotoxicity, apoptosis and in vitro anticancer activity of 1-5 toward SiHa cell line have been investigated by MTT assay and acridine (AO)/ethidium bromide (EthBr) fluorescence staining. Overall results revealed that DNA and protein binding, as well as anticancer activity of 1-5 follows the order as 5 > 3 > 2 > 1 > 4. (C) 2015 Elsevier B.V. All rights reserved.