Zinc complexes of diflunisal: Synthesis, characterization, structure, antioxidant activity, and in vitro and in silico study of the interaction with DNA and albumins

Iron(III) Complexes with Non-Steroidal Anti-Inflammatory Drugs: Structure, Antioxidant and Anticholinergic Activity, and Interaction with Biomolecules

One the main research goals of bioinorganic chemists is the synthesis of novel coordination compounds possessing biological potency. Within this context, three novel iron(III) complexes with the non-steroidal anti-inflammatory drugs diflunisal and diclofenac in the presence or absence of the nitrogen donors 1,10-phenanthroline or pyridine were isolated and characterized by diverse techniques. The complexes were evaluated for their ability to scavenge in vitro free radicals such as hydroxyl, 1,1-diphenyl-2-picrylhydrazyl and 2,2′-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) radicals, revealing their selective potency towards hydroxyl radicals. The in vitro inhibitory activity of the complexes towards the enzymes acetylcholinesterase and butyrylcholinesterase was evaluated, and their potential to achieve neuroprotection appeared promising. The interaction of the complexes with calf-thymus DNA was examined in vitro, revealing their ability to intercalate in-between DNA nucleobases. The affinity of the complexes for serum albumins was evaluated in vitro and revealed their tight and reversible binding.

Synthesis and anticancer mechanisms of zinc(II)-8-hydroxyquinoline complexes with 1,10-phenanthroline ancillary ligands

Twenty new zinc(II) complexes with 8-hydroxyquinoline (H-Q1-H-Q6) in the presence of 1,10-phenanthroline derivatives (D1-D10) were synthesized and formulated as [Zn(Q1)₂(D1)] (DQ1), [Zn(Q2)₂(D2)]·CH₃OH (DQ2), [Zn(Q1)₂(D3)] (DQ3), [Zn(Q1)₂(D4)] (DQ4), [Zn(Q3)₂(D5)] (DQ5), [Zn(Q3)₂(D4)] (DQ6), [Zn(Q4)₂(D5)]·CH₃OH (DQ7), [Zn(Q4)₂(D6)] (DQ8), [Zn(Q4)₂(D3)]·CH₃OH (DQ9), [Zn(Q4)₂(D1)]·H₂O (DQ10), [Zn(Q5)₂(D4)] (DQ11), [Zn(Q6)₂(D6)]·CH₃OH (DQ12), [Zn(Q5)₂(D2)]·5CH₃OH·H₂O (DQ13), [Zn(Q5)₂(D7)]·CH₃OH (DQ14), [Zn(Q5)₂(D8)]·CH₂Cl₂ (DQ15), [Zn(Q5)₂(D9)] (DQ16), [Zn(Q5)₂(D1)] (DQ17), [Zn(Q5)₂(D5)] (DQ18), [Zn(Q5)₂(D10)]·CH₂Cl₂ (DQ19) and [Zn(Q5)₂(D3)] (DQ20). They were characterized using multiple techniques. The cytotoxicity of DQ1-DQ20 was screened using human cisplatin-resistant SK-OV-3/DDP ovarian cancer (SK-OV-3CR) cells and normal hepatocyte (HL-7702) cells. Complex DQ6 showed low IC₅₀ values (2.25 ± 0.13 μM) on SK-OV-3CR cells, more than 3.0-8.0 times more cytotoxic than DQ1-DQ5 and DQ7-DQ20 (≥6.78 μM), and even 22.2 times more cytotoxic than the standard cisplatin, the corresponding free H-Q1-H-Q6 and D1-D10 alone (>50 μM). As a comparison, DQ1-DQ20 displayed nontoxic rates against healthy HL-7702 cells. Furthermore, DQ6 and DQ11 induced significant apoptosis via mitophagy pathways. DQ6 also significantly inhibited tumor growth in an in vivo SK-OV-3-xenograft model (ca. 49.7%). Thus, DQ6 may serve as a lead complex for the discovery of new antitumor agents.

Metal(II) Complexes of the Fluoroquinolone Fleroxacin: Synthesis, Characterization and Biological Profile

A series of complexes of divalent transition metals (Cu(II), Mn(II), Zn(II), Co(II) and Ni(II)) with the quinolone antibacterial agent fleroxacin, in the absence or presence of an α-diimine such as 2,2′-bipyridine, 1,10-phenanthroline or 2,2′-bipyridylamine, were prepared and characterized. The complexes were characterized by various physicochemical and spectroscopic techniques and by single-crystal X-ray crystallography. The in vitro antibacterial activity of the complexes was studied against the bacterial strains Staphylococcus aureus, Bacillus subtilis and Xanthomonas campestris and was higher than that of free quinolone. The affinity of the complexes for bovine and human serum albumin was studied by fluorescence emission spectroscopy and the determined binding constants showed tight and reversible binding to the albumins. The interaction of the complexes with calf-thymus DNA was studied by various techniques, which showed that intercalation was the most plausible mode of interaction.

NSAID-Based Coordination Compounds for Biomedical Applications: Recent Advances and Developments

After the serendipitous discovery of cisplatin, a platinum-based drug with chemotherapeutic effects, an incredible amount of research in the area of coordination chemistry has been produced. Other transition metal compounds were studied, and several new relevant metallodrugs have been synthetized in the past few years. This review is focused on coordination compounds with first-row transition metals, namely, copper, cobalt, nickel or manganese, or with zinc, which have potential or effective pharmacological properties. It is known that metal complexes, once bound to organic drugs, can enhance the drugs’ biological activities, such as anticancer, antimicrobial or anti-inflammatory ones. NSAIDs are a class of compounds with anti-inflammatory properties used to treat pain or fever. NSAIDs’ properties can be strongly improved when included in complexes using their compositional N and O donor atoms, which facilitate their coordination to metal ions. This review focuses on the research on this topic and on the promising or effective results that complexes of first-row transition metals and NSAIDs can exhibit.

Coordination compounds of biogenic metals as cytotoxic agents in cancer therapy

The review summarizes the data on the structures and methods for the synthesis of compounds with anticancer activity based on biogenic metals, which can replace platinum drugs prevailing in cytotoxic therapy. The main focus is given to the comparison of the mechanisms of the cytotoxic action of these complexes, their efficacy and prospects of their use in clinical practice. This is the first systematic review of cytotoxic zinc, iron, cobalt and copper compounds. The structure – activity relationships and the mechanisms of antitumour action are formulated for each type of metal complexes.

The bibliography includes 181 references.

Synthesis, characterization and (in vitro and in silico) biological activity of a series of dioxouranium(VI) complexes with non-steroidal anti-inflammatory drugs

The reaction of the dioxouranium(VI) ion with a series of non-steroidal anti-inflammatory drugs (NSAIDs), namely mefenamic acid, indomethacin, diclofenac, diflunisal and tolfenamic acid, as ligands in the absence or presence of diverse N,N'-donors (1,10-phenanthroline,2,2'-bipyridine or 2,2'-bipyridylamine) as co-ligands led to the formation of ten complexes bearing the formulas [UO₂(NSAID-O,O')₂(O-donor)₂] or [UO₂(NSAID-O,O')₂(N,N'-donor)], respectively. The complexes were characterized with diverse spectroscopic techniques and the crystal structures of three complexes were determined by single-crystal X-ray crystallography. The biological profile of the resultant complexes was assessed in vitro and in silico. The in vitro studies include their antioxidant properties (ability to scavenge free radicals 1,1-diphenyl-picrylhydrazyl and 2,2'-azinobis(3-ethylbenzothiazoline-6-sulfonic acid) and to reduce H₂O₂), their interaction with DNA (linear calf-thymus DNA or supercoiled circular pBR322 plasmid DNA) and their affinity for serum albumins (bovine and human serum albumin). In silico molecular docking calculations were performed regarding the behavior of the complexes towards DNA and their binding to both albumins.

Supramolecular assemblies involving biologically relevant antiparallel π-stacking and unconventional solvent driven structural topology in maleato and fumarato bridged Zn(ii) coordination polymers: antiproliferative evaluation and theoretical studies

In vitro anticancer activities have been explored in solvent driven maleato and fumarato bridged Zn(ii) coordination polymers involving energetically significant antiparallel π-stacking and enclathrated guest MeOH/H₂O moieties.

Antimicrobial, cytotoxicity, molecular modeling and DNA cleavage/binding studies of zinc-naproxen complex: switching DNA binding mode of naproxen by coordination to zinc ion

The intercalation DNA binding mode of the naproxen, a non-steroidal anti-inflammatory drug, has been reported previously. In this study, calf thymus deoxyribonucleic acid (CT-DNA) binding of zinc-naproxen complex, [Zn(naproxen)₂(MeOH)₂], at physiological pH has been investigated by multi-spectroscopic techniques and molecular docking. Zinc-naproxen complex displays significant binding property to the CT-DNA (K_b = 0.2 × 10⁵ L.mol^-1). All of the experimental results; relative increasing in viscosity of CT-DNA and fluorimetric studies using ethidium bromide (EB) and Hoechst 33258 probes, are indicative of groove binding mode of zinc-naproxen complex to CT-DNA. These results show that the coordination of naproxen to zinc metal switches the mode of binding from intercalation to groove. The molecular modeling also shows that the complex binds to the AT-rich region of minor groove of DNA. Structural and topography changes of DNA in interaction with the complex by atomic force microscopy (AFM) indicated that CT-DNA becomes swollen after interaction. The pUC18 plasmid DNA cleavage ability of zinc-naproxen complex by gel electrophoresis experiments revealed that zinc-naproxen complex cleaved supercoiled pUC18 plasmid DNA to nicked DNA. The cytotoxicity of the zinc complex performed by MTT method on HT29 and MCF7 cancer cell lines and on HEK 293 normal cell lines indicates that zinc complex has no cytotoxic effect on both HT29 and MCF7 cell lines but has better cytotoxicity effect on HEK 293 cell lines compared to cisplatin standard drug. The antimicrobial activity of the complex against Staphylococcus aureus and Escherichia coli bacteria revealed the high antimicrobial activity of the complex.Communicated by Ramaswamy H. Sarma.

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.

Zinc(II) complexes with aromatic nitrogen-containing heterocycles as antifungal agents: Synergistic activity with clinically used drug nystatin

Three novel Zn(II) complexes, [ZnCl₂(qz)₂] (1), [ZnCl₂(1,5-naph)]_n (2) and [ZnCl₂(4,7-phen)₂] (3), where qz is quinazoline, 1,5-naph is 1,5-naphthyridine and 4,7-phen is 4,7-phenanthroline, were synthesized by the reactions of ZnCl₂ and the corresponding N-heterocyclic ligand in 1:2 molar ratio in ethanol at ambient temperature. The characterization of these complexes was done by NMR, IR and UV-Vis spectroscopy, and their crystal structures were determined by single-crystal X-ray diffraction analysis. Complexes 1 and 3 are mononuclear species, in which Zn(II) ion is tetrahedrally coordinated by two nitrogen atoms belonging to two qz or 4,7-phen ligands, respectively, and by two chloride anions, while complex 2 is a 1D coordination polymer that contains 1,5-naph as bridging ligand between two metal ions. In agar disc-diffusion assay, complexes 1-3 manifested good inhibitory activity against two investigated Candida strains (C. albicans and C. parapsilosis), while not inducing toxic effects on the healthy human fibroblast cell line (MRC-5). This activity was not fungicidal, as revealed by the broth microdilution assay, however complex 3 showed the ability to modulate Candida hyphae formation, which is an important process during infection and showed significant synergistic effect with clinically used antifungal polyene nystatin.

Synthesis, characterization, anti-proliferative properties and DNA binding of benzochromene derivatives: Increased Bax/Bcl-2 ratio and caspase-dependent apoptosis in colorectal cancer cell line

3-Amino-1-aryl-1H-benzo[f]chromene-2-carbonitrile derivatives were synthesized from three-component reaction of arylaldehyde, malononitrile and 2-naphthol in the presence of 1, 4-bis(4-ferrocenylbutyl)piperazine as a new catalyst. Cytotoxic potencies of the compounds were tested on HT-29 cells. 3-Amino-1-(4-fluorophenyl)-1H-benzo[f]chromene-2-carbonitrile (4c) was more active among these compounds and was selected for further studies. Apoptosis was investigated by acridine orange/ethidium bromide (AO/EtBr) double staining and flow cytometry. The qRT-PCR was used to analyze the expression of pro- and anti-apoptotic genes. The binding attributes of 4c with calf thymus DNA (ctDNA) was examined using multi-spectroscopic measurements. We found that 4c had potent cytotoxic activity against HT-29 cells with an IC₅₀ value of 60 µM through induction of cell cycle arrest in the sub-G1 phase and apoptosis. RT-PCR analysis demonstrated down-regulation of Bcl-2 expression, while the expression of Bax, caspase-3, -8 and -9 genes was up-regulated in HT-29 cells incubated with 4c compared with control cells. These studies revealed that 4c interacts with DNA through groove binding mode with the intrinsic binding constant (K_b) of 3 × 10² M^-1. Thus, 4c is a valuable candidate for further evaluation as a new series of potent chemotherapeutic family in colon cancer treatment.

Cu(II) and Ni(II) Complexes with New Tridentate NNS Thiosemicarbazones: Synthesis, Characterisation, DNA Interaction, and Antibacterial Activity

This paper reports the synthesis and detailed characterisation of copper(II) and nickel(II) complexes with tridentate thiosemicarbazone ligands H 2 L1 and H 2 L2 derived from 2-acetylpyrazine. The ligands and their metal complexes were characterised by different physicochemical techniques, including elemental and thermogravimetric analysis; UV-Vis, IR, 1H-NMR, and 13C-NMR spectroscopy; molar conductance measurements; and mass spectrometry. The crystal structure of the H 2 L1 ligand was determined by single crystal X-ray diffraction studies. The spectral data showed that the thiosemicarbazone behaves as an NNS tridentate ligand through the nitrogen atoms of the azomethine group and pyrazine ring and the sulphur atom of the thioamide group. Elemental and thermal analyses indicated that the obtained metal complexes had a 1 : 1 stoichiometry (metal-ligand). The interactions between these complexes and calf thymus DNA (CT-DNA) were studied by electronic absorption and viscosity measurements. The activities of these compounds against oxidative DNA cleavage were examined by agarose gel electrophoresis. Cu(II) and Ni(II) complexes can wind DNA strands through groove interactions and promote strand breakage of the plasmid pmCherry under oxidative stress conditions. Moreover, all the complexes could interact more strongly with DNA than could with the free ligands. Finally, the antibacterial activities of the ligands and their complexes were determined by in vitro tests against Gram-positive bacterial strains (S. aureus ATCC 25923, L. monocytogenes ATCC 19115, and B. cereus ATCC 10876) and Gram-negative bacterial strains (E. coli ATCC 25922, S. typhimurium ATCC 14028, and K. pneumoniae ATCC BAA-2146) using the broth microdilution method. The metal complexes showed greater antimicrobial activities than the precursor ligands against some of the microorganisms.

DNA-binding affinity, cytotoxicity, apoptosis, cell cycle inhibition and molecular docking studies of a new stilbene derivative

Stilbene derivatives have been found to possess promising anticancer activities against human cancer cell lines in vitro. In the present study, we have investigated cytotoxic, apoptosis induction and DNA binding activity of new stilbene derivative, (E)-1-(4-Chlorophenyl)-4,5-diphenyl-2-[4-(4-methoxystryl)phenyl]-1H-imidazol (STIM) on K562 chronic myeloid leukemia cell line. Via MTT assay STIM demonstrated cytotoxic activity against K562 cell line with IC₅₀ value of 150 µM. Apoptosis, as the mechanism of cell death, was evaluated by morphological study and flow cytometric analysis. In vitro DNA binding property of STIM has been studied by vital spectroscopic techniques, which indicated that STIM interact with ctDNA through groove binding mode and binding constant (K_b) was estimated to be 6.9 × 10⁴ M^-1. Docking studies revealed that hydrophobic is the most important interaction in STIM-DNA complex, and that the ligand (STIM) interacts with DNA via groove binding mode and the bindiyspng energy was calculated as -13.37 kcal/mol. Taken together, the present study suggests that STIM exhibits anticancer effect on K562 cell line through the induction of apoptosis as well as cell cycle arrest at Sub-G1 phase and also can bind to double helix DNA in vitro.

Synthesis, characterization, DNA binding, topoisomerase I inhibition and antiproliferation activities of three new functionalized terpyridine platinum(II) complexes

Three new platinum(II) complexes with pendent morpholine were synthesized, namely complex 1 ([Pt(L)Cl]CF₃SO₃), complex 2 ([Pt(L)(NH₃)](CF₃SO₃)₂) and complex 3 ([Pt(L)(PPh₃)](CF₃SO₃)₂), where L = 4'-[4-(4-morpholinobutyloxy)phenyl]-2,2':6',2″-terpyridine and PPh₃ = triphenylphosphine. The detailed molecular structures of complex 3, L and its precursor L' (1,4'-[4-(4-bromobutyloxy)phenyl]-2,2':6',2″-terpyridine) were determined by single crystal X-ray diffraction. An evaluation of in vitro cytotoxicity for both ligand and complexes was performed by methyl thiazolyl tetrazolium (MTT) assay in three cancer cell lines and normal cells as the control, respectively. IC₅₀ values of complexes 1-3 were lower than those exhibited for the reference drug cisplatin, and selectivity of these complexes were greater than cisplatin. Among them, complex 3 with a leaving group PPh₃ was found to be the most efficacious complex against certain cell lines, especially for cisplatin-resistant A549cisR cells. These complexes were found to bind DNA, induce efficient DNA unwinding. Meanwhile, topoisomerase (Topo) I inhibitory activities by three complexes were detected, and a minimum inhibitory concentration of 15 μM of complex 3 was found totally inhibit Topo I activity.

In vitro and in silico study of the biological activity of manganese(III) inverse-[9-MC-3]-metallacrowns and manganese(II) complexes with the anti-inflammatory drugs diclofenac or indomethacin

In the present contribution, the biological properties of four manganese complexes with the non-steroidal anti-inflammatory drugs sodium diclofenac (Nadicl) or indomethacin (Hindo) in the presence or absence of salicylaldoxime (Η₂sao), i.e. [Μn₆(O)₂(dicl)₂(sao)₆(CH₃OH)₆] 1, [Μn₆(O)₂(indo)₂(sao)₆(H₂O)₄], 2, [Μn(dicl)₂(CH₃OH)₄], 3, and [Μn(indo)₂(CH₃OH)₄], 4 are presented. More specifically, the in vitro cytotoxic effects of the complexes were evaluated against three cancer cell lines (HeLa, MCF-7 and A549 cells) as well as their combinatory activity with the well-known chemotherapeutic drugs irinotecan, cisplatin, paclitaxel and 5-fluorouracil. The biological activity of the complexes was investigated in vitro by studying their affinity to calf-thymus DNA and their binding towards bovine or human serum albumin (HSA). Molecular docking simulations on the crystal structure of HSA and human estrogen receptor alpha (hERa) were employed in order to study in silico the ability of the studied complexes to bind to these proteins.

Ruthenium–arene complexes with NSAIDs: synthesis, characterization and bioactivity

Two non-steroidal antiinflammatory drugs indomethacin and mefenamic acid were coordinated to Ru(ii)–arenes to afford four new complexes.

Interaction of zinc(II) with the non-steroidal anti-inflammatory drug niflumic acid

The reaction of ZnCl2 with the non-steroidal anti-inflammatory drug niflumic acid (Hnif) resulted in the formation of complex [Zn(nif-O)2(MeOH)4], 1. When this reaction was performed in the presence of a N,N'-donor heterocyclic ligand such as 2,2'-bipyridine (bipy), 2,2'-bipyridylamine (bipyam), 1,10-phenanthroline (phen) and 2,2'-dipyridylketone oxime (Hpko), the complexes [Zn(nif-O,O')(bipy)Cl], 2, [Zn(nif-O)(nif-O,O')2(bipyam)], 3, [Zn(nif-O,O')2(phen)], 4 and [Zn(nif-O)2(Hpko-N,N')2], 5 were formed, respectively. The complexes were characterized by physicochemical and spectroscopic techniques and X-ray crystallography (for complexes 1-3). The complexes can scavenge 1,1-diphenyl-picrylhydrazyl, 2,2'-azinobis(3-ethylbenzothiazoline-6-sulfonic acid) and hydroxyl radicals, may inhibit soybean lipoxygenase and are more active compounds than free Hnif. The interaction of the complexes with serum albumins was monitored by fluorescence emission spectroscopy and the corresponding binding constants were calculated. The affinity of the complexes with calf-thymus DNA was investigated by UV-vis spectroscopy, viscosity measurements and fluorescence emission spectroscopy for the competitive studies of the complexes with ethidium bromide revealing their interaction probably via intercalation.

The discovery of half-sandwich iridium complexes containing lidocaine and (pyren-1-yl)ethynyl derivatives of phenylcyanamide ligands for photodynamic therapy

The new design of two cyclopentadienyl iridium(iii) complexes with (pyren-1-yl)ethynyl derivatives of phenylcyanamide and lidocaine ligands, have been studied for photodynamic therapy.

Nickel(ii)–naproxen mixed-ligand complexes: synthesis, structure, antioxidant activity and interaction with albumins and calf-thymus DNA

Six novel nickel(ii)–naproxen complexes exhibit selective radical scavenging activity, bind tightly to albumins and are DNA-intercalators.