Cytotoxicity of copper(II)-complexes with some S-alkyl derivatives of thiosalicylic acid. Crystal structure of the binuclear copper(II)-complex with S-ethyl derivative of thiosalicylic acid

Docking Studies, Cytotoxicity Evaluation and Interactions of Binuclear Copper(II) Complexes with S-Isoalkyl Derivatives of Thiosalicylic Acid with Some Relevant Biomolecules

The numerous side effects of platinum based chemotherapy has led to the design of new therapeutics with platinum replaced by another transition metal. Here, we investigated the interactions of previously reported copper(II) complexes containing S-isoalkyl derivatives, the salicylic acid with guanosine-5'-monophosphate and calf thymus DNA (CT-DNA) and their antitumor effects, in a colon carcinoma model. All three copper(II) complexes exhibited an affinity for binding to CT-DNA, but there was no indication of intercalation or the displacement of ethidium bromide. Molecular docking studies revealed a significant affinity of the complexes for binding to the minor groove of B-form DNA, which coincided with DNA elongation, and a higher affinity for binding to Z-form DNA, supporting the hypothesis that the complex binding to CT-DNA induces a local transition from B-form to Z-form DNA. These complexes show a moderate, but selective cytotoxic effect toward colon cancer cells in vitro. Binuclear complex of copper(II) with S-isoamyl derivative of thiosalicylic acid showed the highest cytotoxic effect, arrested tumor cells in the G2/M phase of the cell cycle, and significantly reduced the expression of inflammatory molecules pro-IL-1β, TNF-α, ICAM-1, and VCAM-1 in the tissue of primary heterotopic murine colon cancer, which was accompanied by a significantly reduced tumor growth and metastases in the lung and liver.

Synthesis, characterization and cytotoxic activity of binuclear copper(II)-complexes with some S-isoalkyl derivatives of thiosalicylic acid. Crystal structure of the binuclear copper(II)-complex with S-isopropyl derivative of thiosalicylic acid

Isoalkyl (isoalkyl = isopropyl-(L1), isobutyl-(L2) and isoamyl-(L3)) derivatives of thiosalicylic acid (TSA) were prepared by alkylation of TSA with corresponding isoalkyl-chlorides in the alkaline water-ethanol solution. The new free copper(II)-complexes with corresponding S-isoalkyl derivatives of TSA (C1-copper(II)-complex with S-isopropyl derivative of thiosalicylic acid, C2-copper(II)-complex with S-isobutyl derivative of thiosalicylic acid and C3-copper(II)-complex with S-isoamyl derivative of thiosalicylic acid) have been synthesized by direct reaction of copper(II)-nitrate with ligand precursor and then characterized by microanalysis, infrared spectra (IR) and EPR (electron paramagnetic resonance) spectra. The spectroscopically predicted structure of the obtained binuclear copper(II)-complex with S-isopropyl derivative of thiosalicylic acid was confirmed by X-ray analysis. Single crystals suitable for X-ray measurements were obtained by slow crystallization from a water solution. Newly synthesized precursors S-isoalkyl derivatives of thiosalicylic acid and corresponding copper(II)-complexes moderately reduced viability of human and murine lung cancer cells, they showed similar cytotoxic effect on human colorectal cancer cells as cisplatin and lower cytotoxic effect than cisplatin toward normal fibroblasts, evaluated by MTT (3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide) colorimetric technique. All new complexes exhibited apoptotic effect toward lung cancer cells, stronger than cisplatin, whereas only C3 induced significant apoptosis of colorectal cancer cells. Complex C1 showed significant antiproliferative effect against murine lung cancer cells, LLC1, while C2 reduced expression of Ki67 in human colorectal cancer cells. All tested complexes induced cell cycle arrest of HCT116 cells in G2/M phase.

Synthesis, characterization and nucleic acid binding studies of mononuclear copper(II) complexes derived from azo containing O, O donor ligands

Azo linked salicyldehyde and a new 2-hydroxy acetophenone based ligands (HL¹ and HL²) with their copper(II) complexes [Cu(L¹)₂] (1) and [Cu(L²)₂] (2) were synthesized and characterized by spectroscopic methods such as ¹H, 13C NMR, UV-Vis spectroscopy and elemental analyses. Calculation based on Density Functional Theory (DFT), have been performed to obtain optimized structures. Binding studies of these copper (II) complexes with calf thymus DNA (ct-DNA) and torula yeast RNA (t-RNA) were analyzed by absorption spectra, emission spectra and Viscosity studies and Molecular Docking techniques. The absorption spectral study indicated that the copper(II) complexes of 1 and 2 had intrinsic binding constants with DNA or RNA in the range of 7.6 ± 0.2 × 10³ M^-1 or 6.5 ± 0.3 × 10³M^-1 and 5.7 ± 0.4 × 10⁴ M^-1 or 1.8 ± 0.5 × 10³ M^-1 respectively. The synthesized compounds and nucleic acids were simulated by molecular docking to explore more details mode of interaction of the complexes and their orientations in the active site of the receptor.

Designing anticancer copper(II) complexes by optimizing 2-pyridine-thiosemicarbazone ligands

To develop potential next-generation metal anticancer agents, we designed and synthesised five Cu(II) 2-pyridine-thiosemicarbazone complexes by modifying the hydrogen atom at the N-4 position of ligands, and then investigated their structure-activity relationships and anticancer mechanisms. Modification of the N-4 position with different groups caused significant differences in cellular uptake and produced superior antitumor activity. Cu complexes arrested the cell cycle at S phase, leading to down-regulation of levels of cyclin and cyclin-dependent kinases and up-regulation of expression of cyclin-dependent kinase inhibitors. Cu complexes exerted chemotherapeutic effects via activating p53 and inducing production of reactive oxygen species to regulate expression of the B-cell lymphoma-2 family of proteins, causing a change in the mitochondrial membrane potential and release of cytochrome c to form a dimer with apoptosis protease activating factor-1, resulting in activation of caspase-9/3 to induce apoptosis. In addition, Cu complexes inhibited telomerase by down-regulating the c-myc regulator gene and expression of the human telomerase reverse transcriptase.

The organic ester O,O'-diethyl-(S,S)-ethylenediamine-N,N'-di-2-(3-cyclohexyl)propanoate dihydrochloride attenuates murine breast cancer growth and metastasis

Pharmacological treatment of cancer is mostly limited by drug-toxicity and resistance. It has been noticed that new organic ester ligand, O,O’-diethyl-(S,S)-ethylenediamine-N,N’-di-2-(3-cyclohexyl)propanoate dihydrochloride (named DE-EDCP) showed effective cytotoxic capacities against several human and mouse cancer cell lines. However, its effects on tumor growth and metastasis are unexplored. The aim of present study was to examine the ability of DE-EDCP to inhibit 4T1 murine breast cancer growth and progression and to explore possible molecular mechanisms. DE-EDCP exhibited significant tumoricidal activity on human and murine breast cancer cell lines. Further, marked reduction of murine breast cancer growth and progression by DE-EDCP was shown. DE-EDCP exhibits fewer side-effects compared to cisplatin as a conventional chemotherapeutic. Results obtained from in vivo and in vitro experiments indicate that DE-EDCP induces apoptosis and inhibits proliferation of 4T1 cells. DE-EDCP increases percentage of 4T1 cells in late apoptosis, expression of pro-apoptotic Bax and caspase-3, while decreases expression of anti-apoptotic Bcl-2. DE-EDCP treatment increased the percentage of TUNEL-positive nuclei and reduced Ki-67 expression in breast cancer tissue. DE-EDCP decreased expression of cyclin D3 and Ki-67, increased expression of cyclin-dependent kinase inhibitors p16, p21 and p27 and arrested 4T1 cells in G0/G1 cell cycle phase. Expression of STAT3 and downstream regulated molecules, NANOG and SOX2, was reduced in 4T1 cells after DE-EDCP treatment.

In conclusion, DE-EDCP impairs breast cancer growth and progression by triggering cancer cell death and inhibition of cancer cell proliferation. DE-EDCP might be of interest in the development of the new anticancer agent.

Synthesis, Characterization, and Cytotoxicity of Binuclear Cooper(II)-Complexes with some S-Alkenyl Derivatives of Thiosalicyclic Acid

New complexes of copper(II) with S-alkenyl derivatives of thiosalicylic acid (alkenyl = propenyl-(L1), isobutenyl-(L2)) have been synthesized and characterized by microanalysis, infrared spectra, magnetic measurements, and by NMR spectra. The cytotoxic activity of two newly synthesized precursor S-alkenyl derivatives of thiosalicylic acid were tested using an MTT colorimetric technique on HCT-116 human colon carcinoma cells. The cytotoxic effect of the copper(II)- complexes were higher compared to the cytotoxicity of the corresponding ligand (for concentrations from 31.25 to 250 μM). Copper(II)-complexes showed a slightly lower cytotoxicity compared to cisplatin. Complexes of copper(II) with S-alkenyl derivatives of thiosalicylic acid (at concentrations from 250 to 1000 μM) had a cytotoxic effect on HCT-116 cells compared to cisplatin.