Synthesis, characterization, and anticancer activity of Ru(p-cymene) complexes bearing pyrazolyl–pyridine type ligands

Abstract

Ruthenium arene-based complexes have attracted growing interest in overcoming the lack of efficiency of platinum-based chemotherapeutic drugs. Herein, we prepared two pyrazolyl–pyridine type bidentate ligands using 2-acetyl pyridine with biphenyl-4-carbaldehyde and 1-pyrene carbaldehyde. The isolated ligands were utilized to prepare two new Ru(p-cymene) complexes, [Ru(η⁶-p-cymene)(bpy)Cl]PF₆ (Ru–bpy(1)) and [Ru(η⁶-p-cymene)(pyn)Cl]PF₆ (Ru–pyn(2)) and characterized well. Single-crystal X-ray diffraction analysis of Ru–bpy(1) revealed that the complex adopts pseudo-octahedral geometry. The MTT assay was performed on human breast carcinoma (MCF-7), cervical carcinoma (HeLa-S3) and lung adenocarcinoma (A549) cells to determine the in vitro cytotoxicity of the complexes. Although the complexes were found to be insensitive to cervical and lung cancer cells at concentrations of up to 100 μM, both the complexes showed efficient cytotoxicity in breast cancer cells. Moreover, these complexes exhibited apoptosis-inducing activity and cell-free antioxidant activity.