New platinum (II) and palladium (II) complexes of coumarin-thiazole Schiff base with a fluorescent chemosensor properties: Synthesis, spectroscopic characterization, X-ray structure determination, in vitro anticancer activity on various human carcinoma cell lines and computational studies

J Photochem Photobiol B. 2018 Jan;178:428-439. doi: 10.1016/j.jphotobiol.2017.11.030. Epub 2017 Nov 22.

Abstract

A new coumarin-thiazole based Schiff base (Ligand, L) and its Pd(II), Pt(II) complexes; ([Pd(L)2] and [Pt(L)2]), were synthesized and characterized using spectrophotometric techniques (NMR, IR, UV-vis, LC-MS), magnetic moment, and conductivity measurements. A single crystal X-ray analysis for only L was done. The crystals of L have monoclinic crystal system and P21/c space group. To gain insight into the structure of L and its complexes, we used density functional theory (DFT) method to optimize the molecules. The photophysical properties changes were observed after deprotonation of L with CN- via intermolecular charge transfer (ICT). Additionally, as the sensor is a colorimetric and fluorimetric cyanide probe containing active sites such as coumarin-thiazole and imine (CH=N), it showed fast color change from yellow to deep red in the visible region, and yellow fluorescence after CN- addition to the imine bond, in DMSO. The reaction mechanisms of L with CN-, F- and AcO- ions were evaluated using 1H NMR shifts. The results showed that, the reaction of L with CN- ion was due to the deprotonation and addition mechanisms at the same time. The anti-cancer activity of L and its Pd(II) and Pt(II) complexes were evaluated in vitro using MTT assay on the human cancer lines MCF-7 (human breast adenocarcinoma), LS174T (human colon carcinoma), and LNCAP (human prostate adenocarcinoma). The anti-cancer effects of L and its complexes, on human cells, were determined by comparing the half maximal inhibitory concentration (IC50) values. The activity results showed that, the Pd(II) complex of L has higher anti-tumor effect than L and its Pt(II) complex against the tested human breast adenocarcinoma (MCF-7), human prostate adenocarcinoma (LNCAP), and human colon carcinoma (LS174T) cell lines.

Keywords: Anion sensitivity; Anticancer activity; Coumarin-thiazole; Fluorescent chemosensor; Platinum (II) and palladium (II) complexes; Schiff base.

MeSH terms

  • Antineoplastic Agents / chemical synthesis
  • Antineoplastic Agents / chemistry
  • Antineoplastic Agents / toxicity
  • Cell Line, Tumor
  • Cell Survival / drug effects
  • Coordination Complexes / chemical synthesis*
  • Coordination Complexes / chemistry
  • Coordination Complexes / toxicity
  • Coumarins / chemistry
  • Crystallography, X-Ray
  • Humans
  • Hydrogen Bonding
  • MCF-7 Cells
  • Magnetic Resonance Spectroscopy
  • Magnetics
  • Molecular Conformation
  • Palladium / chemistry*
  • Platinum / chemistry*
  • Quantum Theory
  • Schiff Bases / chemistry*
  • Spectrophotometry, Ultraviolet
  • Static Electricity
  • Thiazoles / chemistry

Substances

  • Antineoplastic Agents
  • Coordination Complexes
  • Coumarins
  • Schiff Bases
  • Thiazoles
  • Platinum
  • Palladium
  • coumarin