Synthesis, characterization and antitumor activity of polymeric copper(II) complexes with thiosemicarbazones of 3-methyl-5-oxo-1-phenyl-3-pyrazolin-4-carboxaldehyde and 5-oxo-3-phenyl-3-pyrazolin-4-carboxaldehyde

Biological Activity of Triazolopyrimidine Copper(II) Complexes Modulated by an Auxiliary N-N-Chelating Heterocycle Ligands

Novel complexes of type [Cu(N-N)(dmtp)2(OH2)](ClO4)2·dmtp ((1) N-N: 2,2'-bipyridine; (2) L: 1,10-phenantroline and dmtp: 5,7-dimethyl-1,2,4-triazolo[1,5-a]pyrimidine) were designed in order to obtain biologically active compounds. Complexes were characterized as mononuclear species that crystallized in the space group P-1 of the triclinic system with a square pyramidal geometry around the copper (II). In addition to the antiproliferative effect on murine melanoma B16 cells, complex (1) exhibited low toxicity on normal BJ cells and did not affect membrane integrity. Complex (2) proved to be a more potent antimicrobial in comparison with (1), but both compounds were more active in comparison with dmtp-both against planktonic cells and biofilms. A stronger antimicrobial and antibiofilm effect was noticed against the Gram-positive strains, including methicillin-resistant Staphylococcus aureus (MRSA). Both electron paramagnetic resonance (EPR) and Saccharomyces cerevisiae studies indicated that the complexes were scavengers rather than reactive oxygen species promoters. Their DNA intercalating capacity was evidenced by modifications in both absorption and fluorescence spectra. Furthermore, both complexes exhibited nuclease-like activity, which increased in the presence of hydrogen peroxide.

Triapine Analogues and Their Copper(II) Complexes: Synthesis, Characterization, Solution Speciation, Redox Activity, Cytotoxicity, and mR2 RNR Inhibition

Three new thiosemicarbazones (TSCs) HL¹–HL³ as triapine analogues bearing a redox-active phenolic moiety at the terminal nitrogen atom were prepared. Reactions of HL¹–HL³ with CuCl₂·2H₂O in anoxic methanol afforded three copper(II) complexes, namely, Cu(HL¹)Cl₂ (1), [Cu(L²)Cl] (2′), and Cu(HL³)Cl₂ (3), in good yields. Solution speciation studies revealed that the metal-free ligands are stable as HL¹–HL³ at pH 7.4, while being air-sensitive in the basic pH range. In dimethyl sulfoxide they exist as a mixture of E and Z isomers. A mechanism of the E/Z isomerization with an inversion at the nitrogen atom of the Schiff base imine bond is proposed. The monocationic complexes [Cu(L^1–3)]⁺ are the most abundant species in aqueous solutions at pH 7.4. Electrochemical and spectroelectrochemical studies of 1, 2′, and 3 confirmed their redox activity in both the cathodic and the anodic region of potentials. The one-electron reduction was identified as metal-centered by electron paramagnetic resonance spectroelectrochemistry. An electrochemical oxidation pointed out the ligand-centered oxidation, while chemical oxidations of HL¹ and HL² as well as 1 and 2′ afforded several two-electron and four-electron oxidation products, which were isolated and comprehensively characterized. Complexes 1 and 2′ showed an antiproliferative activity in Colo205 and Colo320 cancer cell lines with half-maximal inhibitory concentration values in the low micromolar concentration range, while 3 with the most closely related ligand to triapine displayed the best selectivity for cancer cells versus normal fibroblast cells (MRC-5). HL¹ and 1 in the presence of 1,4-dithiothreitol are as potent inhibitors of mR2 ribonucleotide reductase as triapine.

Three triapine analogues HL¹−HL³ bearing a phenolic redox-active moiety showed moderate antiproliferative activity, while one of the oxidation products HL^2c′·CH3COOH revealed high cytotoxicity in Colo205 and Colo320 cancer cell lines. Coordination of HL¹−HL³ to copper(II) increased strongly the cytotoxicity, with complex 2′ showing IC₅₀ values of 0.181 and 0.159, respectively. The highest cytotoxicity of 2′ is likely due to the highest thermodynamic stability, more negative reduction potential, and the lowest rate of reduction by GSH.

Antitumor effect of a pyrazolone-based-complex [Cu(PMPP-SAL)(EtOH)] against murine melanoma B16 cell in vitro and in vivo

Pyrazolone-based derivative metal complexes were reported to have cytotoxicity in some tumor cells. In this study, the antitumor effect of [Cu(PMPP-SAL)(EtOH)] (PMPP-SAL = N-(1-phenyl-3-methyl-4-propenylidene-5-pyrazolone)- salicylidene hydrazide anion) in murine melanoma B16 cells in vitro and in vivo was investigated. The results showed that [Cu(PMPP-SAL)(EtOH)] inhibited the survival of B16 cells in vitro, and the IC50 value was superior to cisplatin (DDP) (p < 0.001). B16 cell apoptosis was significantly higher in comparison to the control group (DMSO) (p < 0.01), and cell cycle arrest occurred at the G0/G1 phase. When challenged C57 BL/6J mice were treated with [Cu(PMPPSAL)(EtOH)], a smaller volume of B16 solid tumors were reported than the control group (p < 0.01), with lower positive expression indices of CD 34, vascular endothelial growth factor (VEGF) and basic fibroblast growth factor (bFGF) (p < 0.01). Moreover, the tumor growth was suppressed in mice due to the induction of apoptosis, as detected by the TUNEL assay (p < 0.001). In summary, [Cu(PMPP-SAL)(EtOH)] effectively inhibited the growth of B16 cells in vitro and in vivo due to the induction of apoptosis and the inhibition of intra-tumoral angiogenesis, demonstrating its therapeutic potential in melanoma treatment.

Synthesis, Characterization, and In Vivo Anti-Cancer Activity of New Metal Complexes Derived from Isatin-N(4)antipyrinethiosemicarbazone Ligand Against Ehrlich Ascites Carcinoma Cells

The current study aimed to synthesize new metal coordination complexes with potential biomedical applications. Metal complexes were prepared via the reaction of isatin-N(4)anti- pyrinethiosemicarbazone ligand 1 with Cu(II), Ni(II), Co(II), Zn(II), and Fe(III) ions. The obtained metal complexes 2-12 were characterized using elemental, spectral (¹H-NMR, EPR, Mass, IR, UV-Vis) and thermal (TGA) techniques, as well as magnetic moment and molar conductance measurements. In addition, their geometries were studied using EPR and UV-Vis spectroscopy. To evaluate the in vivo anti-cancer activities of these complexes, the ligand 1 and its metal complexes 2, 7 and 9 were tested against solid tumors. The solid tumors were induced by subcutaneous (SC) injection of Ehrlich ascites carcinoma (EAC) cells in mice. The impact of the selected complexes on the reduction of tumor volume was determined. Also, the expression levels of vascular endothelial growth factor (VEGF) and cysteine aspartyl-specific protease-7 (caspase-7) in tumor and liver tissues of mice bearing EAC tumor were determined. Moreover, their effects on alanine transaminase (ALT), aspartate transaminase (AST), albumin, and glucose levels were measured. The results revealed that the tested compounds, especially complex 9, reduced tumor volume, inhibited the expression of VEGF, and induced the expression of caspase-7. Additionally, they restored the levels of ALT, AST, albumin, and glucose close to their normal levels. Taken together, our newly synthesized metal complexes are promising anti-cancer agents against solid tumors induced by EAC cells as supported by the inhibition of VEGF and induction of caspase-7.

Copper(ii) complexes with 4-acyl pyrazolone derivatives and diimine coligands: synthesis, structural characterization, DNA binding and antitumor activity

Three copper complexes of 4-acyl pyrazolone derivatives were constructed. Their DNA binding and cancer cell inhibitory activities were investigated.

Unfolding biological properties of a versatile dicopper(II) precursor and its two mononuclear copper(II) derivatives

Synthesis, inter-conversions and biological study of the dichloro bridged dicopper(II) compound [CuLCl]₂ (1) and its two mononuclear derivatives [CuLCl(H₂O)]·H₂O (2) and [CuLCl(py)] (3) (HL=2-(2-pyridylmethyleneamino)benzenesulfonic acid) are described. The dimeric compound 1 collapses into monomers 2 and 3 in the presence of coordinating solvents, water and pyridine, respectively, and 1 is regenerated upon simple stirring of 2 or 3 in methanol. The reactions of 1 with neutral (present study) and charged (earlier studies) ligands result in monomeric and multimeric compounds, respectively, attesting that it is a versatile dicopper(II) precursor. The anticancer activity of these copper complexes (1-3) was screened against lung (A-549) and breast (MDA-MB-231) human cancer cell lines. The IC₅₀ (half maximal inhibitory concentration) value for one (3) of the compounds suggests preferential cytotoxicity against breast cancer MDA-MB-231 cell line. Furthermore, the IC₅₀ value obtained for complex 3 is found to be almost two-fold times cytotoxic than the standard drug cisplatin. In addition, the underlying possible mechanism of its apoptosis-inducing efficacy in MDA-MB-231 cells has been rationalized by using flow cytometry (FACS) and Hoechst 33342/propidium iodide (PI) fluorescence staining. The stimulation of apoptotic induction for complex 3 has further been affirmed by reactive oxygen species (ROS) generation and mitochondrial aggregations studies.

Pyrazolone incorporating bipyridyl metallointercalators as effective DNA, protein and lung cancer targets: Synthesis, characterization and in vitro biocidal evaluation

Pyrazolone based metal complexes have strong bio-activity but the anti-cancer mechanism of these derivatives is not fully understood. In recent years, Cu(II) complexes have attracted the interest of researchers increasingly because of their high antitumor activities that are usually related to DNA binding. The reaction of three different derivatives (I) PPMP [3-methyl-1-phenyl-4-propionyl-1H-pyrazol-5(4H)-one], (II) TMCPMP [1-(3-chlorophenyl)-3-methyl-4-(4-methylbenzoyl)-1H-pyrazol-5(4H)-one] and (III) PPTPMP [3-methyl-4-propionyl-1-p-tolyl-1H-pyrazol-5(4H)-one] of 3-methyl-1-phenyl-1H-pyrazol-5(4H)-one and 2.2' bipyridyl along with Cu(NO3)2·3H2O under methanolic condition allowed us to isolate and characterize a series of new mixed ligand complexes [Cu(TMCPMP) (Bipy)NCS] (1) [Cu(PPMP) (Bipy)NCS] (2) and [Cu(PPTPMP) (Bipy)NCS] (3). All complexes are well characterized by elemental analysis, metal estimation, molar conductivity, FT-IR and UV-Vis spectroscopy. The molecular geometry of these complexes has been determined by single crystal X-ray study. The single-crystal X-ray structures of complexes 1 and 2 exhibit square pyramidal geometry, while complex 3 revealed slightly distorted square-pyramidal geometry. The DNA binding of these compounds with Calf-Thymus DNA (CT-DNA) has been explored by emission titration methods, which revealed that 1-3 could interact with CT-DNA through intercalation mode. The complexes also exhibited a strong binding with Bovine Serum Albumin (BSA) over the ligands. Complexes were evaluated for their in vitro cytotoxic activities against lung cancer cell lines (A549) as well as noncancerous rat cardiomyocytes (H9C2) cell lines, which showed that all three complexes exhibited substantial cytotoxic activity with minimum effect on noncancerous cells. Complex 1 with more hydrophobic environment exhibited relatively high cytotoxic activity towards A549 cells. In summary, this new series of compounds belongs to a class of copper-pyrazolonate complexes that target many biochemical sites and with potential anti-cancer activity. All these results collectively suggested that complexes could serve as promising pharmacologically active substance against lung cancer.

Antibacterial, antifungal and in vitro antileukaemia activity of metal complexes with thiosemicarbazones

1-phenyl-3-methyl-4-benzoyl-5-pyrazolone 4-ethyl-thiosemicarbazone (HL) and its copper(II), vanadium(V) and nickel(II) complexes: [Cu(L)(Cl)]·C₂H₅OH·(1), [Cu(L)₂]·H₂O (2), [Cu(L)(Br)]·H₂O·CH₃OH (3), [Cu(L)(NO₃)]·2C₂H₅OH (4), [VO₂(L)]·2H₂O (5), [Ni(L)₂]·H₂O (6), were synthesized and characterized. The ligand has been characterized by elemental analyses, IR, ¹H NMR and ¹³C NMR spectroscopy. The tridentate nature of the ligand is evident from the IR spectra. The copper(II), vanadium(V) and nickel(II) complexes have been characterized by different physico-chemical techniques such as molar conductivity, magnetic susceptibility measurements and electronic, infrared and electron paramagnetic resonance spectral studies. The structures of the ligand and its copper(II) (2, 4), and vanadium(V) (5) complexes have been determined by single-crystal X-ray diffraction. The composition of the coordination polyhedron of the central atom in 2, 4 and 5 is different. The tetrahedral coordination geometry of Cu was found in complex 2 while in complex 4, it is square planar, in complex 5 the coordination polyhedron of the central ion is distorted square pyramid. The in vitro antibacterial activity of the complexes against Escherichia coli, Salmonella abony, Staphylococcus aureus, Bacillus cereus and the antifungal activity against Candida albicans strains was higher for the metal complexes than for free ligand. The effect of the free ligand and its metal complexes on the proliferation of HL-60 cells was tested.

Synthesis, X-ray structure and in vitro cytotoxicity studies of Cu(i/ii) complexes of thiosemicarbazone: special emphasis on their interactions with DNA

The interactions of four Cu-TSC complexes with DNA & their cytotoxicity studies against the HeLa cell have been reported.

Synthesis and characterization of some new Cu(II), Ni(II) and Zn(II) complexes with salicylidene thiosemicarbazones: antibacterial, antifungal and in vitro antileukemia activity

Thirty two new Cu(II), Ni(II) and Zn(II) complexes (1–32) with salicylidene thiosemicarbazones (H₂L¹–H₂L¹⁰) were synthesized. Salicylidene thiosemicarbazones, of general formula (X)N-NH-C(S)-NH(Y), were prepared through the condensation reaction of 2-hydroxybenzaldehyde and its derivatives (X) with thiosemicarbazide or 4-phenylthiosemicarbazide (Y = H, C₆H₅). The characterization of the new formed compounds was done by ¹H-NMR, ¹³C-NMR, IR spectroscopy, elemental analysis, magnetochemical, thermoanalytical and molar conductance measurements. In addition, the structure of the complex 5 has been determined by X-ray diffraction method. All ligands and metal complexes were tested as inhibitors of human leukemia (HL-60) cells growth and antibacterial and antifungal activities.