New copper(II) niflumate complexes with N-donor ligands: Synthesis, characterization and evaluation of anticancer potential against human cell lines

Structural and Biological Properties of Heteroligand Copper Complexes with Diethylnicotinamide and Various Fenamates: Preparation, Structure, Spectral Properties and Hirshfeld Surface Analysis

Herein, we discuss the synthesis, structural and spectroscopic characterization, and biological activity of five heteroligand copper(II) complexes with diethylnicotinamide and various fenamates, as follows: flufenamate (fluf), niflumate (nifl), tolfenamate (tolf), clonixinate (clon), mefenamate (mef) and N, N-diethylnicotinamide (dena). The complexes of composition: [Cu(fluf)2(dena)2(H2O)2] (1), [Cu(nifl)2(dena)2] (2), [Cu(tolf)2(dena)2(H2O)2] (3), [Cu(clon)2(dena)2] (4) and [Cu(mef)2(dena)2(H2O)2] (5), were synthesized, structurally (single-crystal X-ray diffraction) and spectroscopically characterized (IR, EA, UV-Vis and EPR). The studied complexes are monomeric, forming a distorted tetragonal bipyramidal stereochemistry around the central copper ion. The crystal structures of all five complexes were determined and refined with an aspheric model using the Hirshfeld atom refinement method. Hirshfeld surface analysis and fingerprint plots were used to investigate the intermolecular interactions in the crystalline state. The redox properties of the complexes were studied and evaluated via cyclic voltammetry. The complexes exhibited good superoxide scavenging activity as determined by an NBT assay along with a copper-based redox-cycling mechanism, resulting in the formation of ROS, which, in turn, predisposed the studied complexes for their anticancer activity. The ability of complexes 1–4 to interact with calf thymus DNA was investigated using absorption titrations, viscosity measurements and an ethidium-bromide-displacement-fluorescence-based method, suggesting mainly the intercalative binding of the complexes to DNA. The affinity of complexes 1–4 for bovine serum albumin was determined via fluorescence emission spectroscopy and was quantitatively characterized with the corresponding binding constants. The cytotoxic properties of complexes 1–4 were studied using the cancer cell lines A549, MCF-7 and U-118MG, as well as healthy MRC-5 cells. Complex 4 exhibited moderate anticancer activity on the MCF-7 cancer cells with IC50 = 57 μM.

In Vitro Anticancer Activity of Novel Co(II) and Ni(II) Complexes of Non-steroidal Anti-inflammatory Drug Niflumic Acid Against Human Breast Adenocarcinoma MCF-7 Cells

Herein, we report the synthesis, characterization and anticancer activity of six novel complexes of non-steroidal anti-inflammatory drug niflumic acid with Co(II) and Ni(II). In vitro cytotoxicity screening in MCF-7, HepG2 and HT-29 cancer cell lines showed that the complex 3 [Co(nif)2(met)(4-pic)] and complex 6 [Ni(nif)2(met)(4-pic)] among all the complexes exhibited the highest cytotoxicity against MCF-7 cells with IC50 values of 11.14 µM and, 41.47 µM, respectively. Besides, all the complexes exhibited significantly higher selectivity towards mouse fibroblast 3T3L1 cells. Further mechanistic studies with both complexes on MCF-7 cells revealed their cytotoxic action through the mitochondrial-dependent apoptotic pathway causing an increase oxidative/nitrosative stress, decrease in mitochondrial membrane potential (ΔΨm), inducing the multicaspase activation and arresting the cell cycle at S phase. q-PCR analysis resulted in an increase in the expression of the apoptotic marker proteins bax, p53 and caspase-3 and -8 in MCF-7 cells, but a decrease in the expression of antiapoptotic bcl-2 gene. Moreover, both complexes induced the apoptosis through the inhibition of PI3K/Akt signaling pathway by decreasing the expression of PI3K and increasing dephosphorylation form of Akt protein. These results provide a significant contribution to the explanation of the anticancer mechanisms of these complexes in MCF-7 cells.

CuII Complexes and Coordination Polymers with Pyridine or Pyrazine Amides and Amino Benzamides—Structures and EPR Patterns

Isonicotine amide, picoline amide, pyrazine 2-amide, 2- and 4-amino benzamides and various CuII salts were used to target CuII complexes of these ligands alongside with 1D and 2D coordination polymers. Under the criterion of obtaining crystalline and single phased materials a number of new compounds were reliably reproduced. Remarkably, for some of these compounds the ideal Cu:ligand ratio of the starting materials turned out to be very different from Cu:ligand ratio in the products. Crystal and molecular structures from single-crystal XRD were obtained for all new compounds; phase purity was checked using powder XRD. We observed exclusively the Oamide and not the NH2amide function binding to CuII. In most of the cases; this occurred in chelates with the second pyridine, pyrazine or aminophenyl N function. µ-O,N ditopic bridging was frequently observed for the N = pyridine, pyrazine or aminophenyl functions, but not exclusively. The geometry around CuII in these compounds was very often axially elongated octahedral or square pyramidal. X-band EPR spectra of powder samples revealed various spectral symmetry patterns ranging from axial over rhombic to inverse axial. Although the EPR spectra cannot be unequivocally correlated to the observed geometry of CuII in the solid state structures, the EPR patterns can help to support assumed structures as shown for the compound [Cu(Ina)2Br2] (Ina = isonicotine amide). As UV-vis absorption spectroscopy and magnetic measurement in the solid can also be roughly correlated to the surrounding of CuII, we suggest the combination of EPR, UV-vis spectroscopy and magnetic measurements to elucidate possible structures of CuII compounds with such ligands.

Two isostructural Co(II) flufenamato and niflumato complexes with bathocuproine: Analogues with a different cytotoxic activity

Two novel Co(II) fenamato complexes containing bathocuproine (bcp), namely [Co(bcp)(flu)₂] (1) and [Co(bcp)(nif)₂] (2) (flu = flufenamato, nif = niflumato) were synthesized and characterized by elemental analysis, single-crystal X-ray structure analysis as well as absorption and fluorescence spectroscopy. Investigation of their molecular structure revealed that both complexes are isostructural and form analogous complex molecules, with a Co(II) atom hexacoordinated by two nitrogen atoms of bcp and four oxygen atoms of two chelate bonded flu (1) and nif (2) ligands in a distorted octahedral arrangement. Surprisingly, the results of cytotoxicity experiments on four cancer cell lines (HeLa, HT-29, PC-3 and MCF-7) have revealed that despite similar structure of the complexes, the nif complex exhibits significantly higher activity, being the most effective against the PC-3 cell line (IC₅₀ (MTT) = 6.11 ± 1.95 μM). Further studies performed on PC-3 cell line have shown that the mechanism of the cytotoxic action of nif complex (2) might involve activation of autophagic processes and apoptosis, while for its flu analogue (1) apoptosis was detected.

Synthesis, characterization, and in vitro effect of the Cu(II) complex with niflumic acid and 3-picoline on paraoxanase-I

Niflumic acid is used to treat inflammatory rheumatoid diseases, pain, and fever. The present study reports the experimental, spectroscopic, thermal, structural analyses, and biological activities of this complex. The nonsteroidal anti-inflammatory drug niflumic acid, 3-picoline, and copper(II) chloride were utilized to synthesize a new complex: [Cu₂ Cl ₂ (nif) ₂ (3-pic) ₄ ]. The crystal structure of [Cu ₂ Cl ₂ (nif) ₂ (3-pic) ₄ ] was determined by X-ray crystallography. The complex crystallizes in the triclinic space group P-1 and each Cu(II) center displayed six-coordinated distorted octahedral geometry. Two Cu(II) centers are connected by a chloro-bridge to form the binuclear metal core. Finally, the in vitro effects of the synthesized new complex and free niflumic acid were evaluated on the human serum paraoxonase 1 enzyme. At low doses, both the new complex and free niflumic acid showed very good inhibition activity with different inhibition mechanisms. In addition, the results showed that the new complex has more inhibition activity than free niflumic acid.