Synthesis, structure, DNA/protein binding, and cytotoxic activity of a rhodium(III) complex with 2,6-bis(2-benzimidazolyl)pyridine.
A new mononuclear rhodium(III) complex, [Rh(bzimpy)Cl3] (bzimpy = 2,6-bis(2-benzimidazolyl)pyridine), was synthesized and characterized by elemental analysis and spectroscopic methods. The molecular structure of the complex was confirmed by single-crystal X-ray crystallography. The interaction of the complex with fish sperm DNA (FS-DNA) was investigated by UV spectroscopy, emission titration, and viscosity measurement in order to evaluate the possible DNA-binding mode and to calculate the corresponding DNA-binding constant. The results reveal that the Rh(III) complex interacts with DNA through groove binding mode with a binding affinity on the order of 104. In addition, the binding of the Rh(III) complex to bovine serum albumin (BSA) was monitored by UV-Vis and fluorescence emission spectroscopy at different temperatures. The mechanism of the complex interaction was found to be static quenching. The thermodynamic parameters (ΔH, ΔS, and ΔG) obtained from the fluorescence spectroscopy data show that van der Waals interactions and hydrogen bonds play a major role in the binding of the Rh(III) complex to BSA. For the comparison of the DNA- and BSA-binding affinities of the free bzimpy ligand with its Rh(III) complex, the absorbance titration and fluorescence quenching experiments of the free bzimpy ligand with DNA and BSA were carried out. Competitive experiments using eosin Y and ibuprofen as site markers indicated that the complex was mainly located in the hydrophobic cavity of site I of the protein. These experimental results were confirmed by the results of molecular docking. Finally, the in vitro cytotoxicity properties of the Rh(III) complex against the MCF-7, K562, and HT-29 cell lines were evaluated and compared with those of the free ligand (bzimpy). It was found that the complexation process improved the anticancer activity significantly.
Department of Chemistry, Isfahan University of Technology, Isfahan 84156-83111, Iran.
Roya
R
Esteghamat-Panah
Department of Chemistry, Isfahan University of Technology, Isfahan 84156-83111, Iran. Electronic address: hadad@cc.iut.ac.ir.
Hassan
H
Hadadzadeh
Department of Chemistry, Isfahan University of Technology, Isfahan 84156-83111, Iran.
Hossein
H
Farrokhpour
Department of Chemistry, University of Otago, P.O. Box 56, Dunedin 9054, New Zealand.
Jim
J
Simpson
Department of Chemistry, Isfahan University of Technology, Isfahan 84156-83111, Iran.
Amir
A
Abdolmaleki
Department of Engineering, Ardakan University, Ardakan 89518-95491, Iran.
Fatemeh
F
Abyar
D000818:Animals; D000970:Antineoplastic Agents / Q000138:chemical synthesis* / Q000737:chemistry / Q000378:metabolism / Q000494:pharmacology*; D001562:Benzimidazoles / Q000737:chemistry*; D002417:Cattle; D045744:Cell Line, Tumor; D060326:Chemistry Techniques, Synthetic; D004247:DNA / Q000737:chemistry / Q000378:metabolism*; D008958:Models, Molecular; D009690:Nucleic Acid Conformation; D009942:Organometallic Compounds / Q000138:chemical synthesis* / Q000737:chemistry / Q000378:metabolism / Q000494:pharmacology*; D011485:Protein Binding; D011725:Pyridines / Q000737:chemistry*; D012238:Rhodium / Q000737:chemistry*; D012710:Serum Albumin, Bovine / Q000378:metabolism; D013816:Thermodynamics
C500137:2,6-bis(benzimidazol-2-yl)pyridine; D000970:Antineoplastic Agents; D001562:Benzimidazoles; D009942:Organometallic Compounds; D011725:Pyridines; D012710:Serum Albumin, Bovine; D004247:DNA; D012238:Rhodium
2,6-bis(2-benzimidazolyl)pyridine based ligand; Cancer cells; Cytotoxicity; DNA/protein binding; Molecular docking; Rhodium(III) complex