Cu(II), Ni(II) complexes derived from chiral Schiff-base ligands: Synthesis, characterization, cytotoxicity, protein and DNA–binding properties

Structural investigations and antibacterial, antifungal and anticancer studies on zinc salicylaldimine complexes

Aim: Zinc salicylaldimines may act as multidrug agents. Results: Three zinc salicylaldimines C1-C3 and respective ligands HL1-HL3 were examined for antimicrobial/anticancer drug action and C3 was structurally analyzed (tetrahedral, triclinic). Against two fungi, C1 inhibited Candida albicans with 12 mm (21 mm for amphotericin B). Among four bacteria, two ligands inhibited Staphylococcus aureus and Escherichia coli (9-10 mm), but the complexes inhibited all bacteria with 10-14 mm (21-26 mm for ampicillin). The half-maximal inhibitory concentrations for the ligands, complexes and doxorubicin were 195.5-310.7, 22.18-70.05 and 9.66 μM against cancerous MCF-7 cells and 186.4-199.9, 14.95-18.87 and 36.42 μM against normal BHK cells. Conclusion: The complexation produced pronounced enhancement in the ligand antimicrobial/anticancer activities, despite these activities are moderate comparing with standards.

Antibacterial activity and DNA interaction of triazine iron and ruthenium complexes: spectroscopic, voltammetric and theoretical studies

The 2,4,6-tris(2-pyridyl)-1,3,5-triazine (tptz), [Ru(μ-tptz)2]Cl2 and [Fe(μ-tptz)2]Cl2, complexes containing Ru (1) and Fe (2) are created. Using electronic absorption spectroscopy, fluorescence spectroscopy, circular dichroism spectroscopy, viscosity measurement and electrochemistry, as well as two complexes with Fish Salmon DNA (FS-DNA), the binding interactions of these complexes were investigated. According to binding assays, complexes bind to DNA through a mild intercalation mechanism, most likely via the DNA helix's base pairs being intercalated by the tptz ligand. Additionally, complex (2) is more capable of binding than complex (1). The electrochemical method offers a quick and easy way to determine the binding constant (Kb). The antibacterial performance of these complexes versus Gram-positive and Gram-negative bacteria was examined using the zone of inhibition test, MIC, and MBC method, and the results revealed that complex (2) exhibits strong antibacterial activity against these bacteria. The outcomes of this investigation will help in understanding DNA interaction mechanisms as well as the creation of a prospective one. Additionally, the density functional theory (DFT) computation included probes of DNA structure and conformation as well as potential pharmacological regulators for particular disorders to fully explain the experimental results.

In vitro biological activity of cobalt(II) complexes with salicylaldimine ligands in microbial and cancer cells

Background: More studies using cobalt complexes as drugs are needed. Results: The drug action of two cobalt salicylaldimines was determined. The complexes and amphotericin B (20 mg/ml) inhibited Candida albicans at 9-15 and 21 mm. This concentration of both ligands inhibited Staphylococcus aureus at 10 mm and one ligand inhibited Escherichia coli at 9 mm, but the complexes and ampicillin inhibited four bacteria at 9-20 and 21-26 mm. The ligands were inactive against cancer and normal cells, but the complexes and doxorubicin provided IC50 values of 28.18-54.19 and 9.66 μM against MCF-7 cells and 15.76-20.49 and 36.42 μM against BHK cells. Conclusion: The ligands' activity was much improved by complexation, although they remained substandard.

Interaction with bioligands and in vitro cytotoxicity of a new dinuclear dioxido vanadium(V) complex

One centrosymmetric bis(μ-oxido)-bridged vanadium(V) dimer with molecular formula [(V^VO₂)₂(pedf)₂] (1) has been synthesized from the reaction of VOSO₄·5H₂O with a Schiff base ligand (abbreviated with pedf^-) obtained from 2-acetylpyridine and 2-furoic hydrazide in methanol. Complex 1 was characterized by elemental analysis, UV-visible (UV-Vis), Fourier-transform infrared spectra (FT-IR), cyclic voltammetry (CV), electron paramagnetic resonance spectroscopy (EPR) and electrospray ionization-mass spectrometry (ESI-MS) techniques along with single crystal X-ray diffraction (SCXRD). The FT-IR spectral data of 1 indicated the involvement of oxygen and azomethine nitrogen in coordination to the central metal ion. The crystallographic studies revealed a dinuclear oxovanadium(V) complex with the Schiff base coordinated via the ONN donor set with formation of two five-membered chelate rings resulting in a distorted octahedral geometry. The interaction of 1 with calf thymus DNA (CT-DNA) was investigated by spectroscopic measurements and results suggested that the complex binds to CT-DNA via moderate intercalative mode with a binding constant (K_b) around 10³ M^-1. In addition, the in vitro protein binding behavior was studied by fluorescence spectrophotometric method using both bovine serum albumin (BSA) and human serum albumin (HSA) and a static quenching mechanism was observed for the interaction of the complex with both albumins that occurs with a K_b in the range (5-6) × 10³ M^-1. In vitro cytotoxicity of complex 1 on lung cancer cells (A549) and human skin carcinoma cell line (A431) demonstrated that the complex had a broad-spectrum of anti-proliferative activity with IC₅₀ value of 64.2 μM and 56.2 μM.

Transition Metal Complexes with Tridentate Schiff Bases (O N O and O N N) Derived from Salicylaldehyde: An Analysis of Their Potential Anticancer Activity

Although it is known that the first case of cancer was recorded in ancient Egypt around 1600 BC, it was not until 1917 during the First World War and the development of mustard gas that chemotherapy against cancer became relevant; however, its properties were not recognised until 1946 to later be used in patients. In this sense, the use of metallopharmaceuticals in cancer therapy was extensively explored until the 1960s with the discovery of cisplatin and its anticancer activity. From that date to the present, the search for more effective, more selective metallodrugs with fewer side effects has been an area of continuous exploration. Efforts have led to considering a wide variety of metals from the periodic table, mainly from the d-block, as well as a wide variety of organic ligands, preferably with proven biological activity. In this sense, various research groups have found an ideal binder in Schiff bases, since their raw materials are easily accessible, their synthesis conditions are friendly and their denticity can be manipulated. Therefore, in this review, we have explored the anticancer and antitumor activity reported in the literature for coordination complexes of d-block metals coordinated with tridentate Schiff bases (O N O and O N N) derived from salicylaldehyde. For this work, we have used the main scientific databases CCDC® and SciFinder®.

Co(II), Ni(II), and Zn(II) complexes based on new hybrid imine-pyrazole ligands: structural, spectroscopic, and electronic properties

The present work reports the theoretical investigation of Co(II), Ni(II), and Zn(II) complexes containing Schiff bases (used as ligands) derived from the reaction of 2-hydroxy-1-naphthaldehyde with N-(2-aminoethyl) pyrazoles. The spectral analyses were carried out using infrared, Raman, and UV-Vis spectroscopy. Vibrational analyses were performed in order to investigate the mechanisms involving metal-ligand and intra-ligand vibrations and indicated the possibility of charge transfer related to the transitions n[Formula: see text]* and [Formula: see text]*. Structure optimizations and normal coordinate force field calculations were performed via the density functional theory (DFT) method at the HSE06/6-311G(d,p)/LanL2DZ level. A thorough analysis was also conducted regarding the nonlinear optical (NLO) properties and the natural bond orbital (NBO) of the complexes. The results show that these complexes have prospective application as materials for NLO. Furthermore, the NBO analysis confirms the coordination between the lone pair (LP) electrons of the donor atoms (O and N) and the metal acceptors. Finally, studies were conducted regarding the electronic properties of the complexes; among the properties investigated included the frontier molecular orbitals (FMO) and the molecular electrostatic potential (MEP), allowing to determine the energy gap and charge distribution.

Recent Advances in Schiff Base Ruthenium Metal Complexes: Synthesis and Applications

This review concentrates on recent developments in ruthenium Schiff bases, whose steric and electronic characteristics can be manipulated easily by selecting suitable condensing aldehydes or ketones and primary amines, and their metal complexes. Ruthenium metal-based complexes and Schiff base ligands are rapidly becoming conventionally considered for biological applications (antioxidant, anticancer, antimicrobial), in catalysis, in functional materials, in sensors, and as pigments for dyes. Ruthenium complexes exhibit a broad variety of activities concerning simple Schiff base ligands. This may be due to the octahedral bonding of both Ru(II) and Ru(III) complexes, which acquire an extended reservoir of a three-dimensional framework, providing the potential for an elevated degree of site selectivity for binding to their biological targets. This review provides an overview of this field, and intends to highlight both ligand design and synthetic methodology development, as well as significant applications of these metal complexes. In this review, we summarize our work on the development of ruthenium complexes, which was performed over the last few years.

Synthesis, crystal structure, Hirshfeld surface analysis, DNA binding, DNA cleavage activity and molecular docking of a new Schiff base nickel(II) complex

A mononuclear nickel(II) complex, [Ni(o-van-tris)₂]·2H₂O (o-van-tris = Schiff base derived from o-vanillin and tris(hydroxymethyl)aminomethane), has been synthesized and structurally characterized. The single crystal structure shows a distorted octahedron geometry coordinated with Ni(II) atom, and 2 D plane structure has formed by O-H···O hydrogen bond interactions. An analysis to ascertain intermolecular interactions of the complex was performed based on the Hirshfeld surfaces and their associated two-dimensional fingerprint plots. The binding properties of the nickel(II) complex with CT-DNA have been investigated by spectroscopic methods and molecular docking. Absorption and fluorescence spectral studies reveal that the complex interacts with DNA through hydrogen bond and hydrophobic interactions with the DNA base pairs. Molecular docking studies show that the complex effectively docks in the major groove of DNA. The DNA cleavage experiment was performed by gel electrophoretic assay, indicating that DNA cleavage activity of the complex is concentration dependent and much sensitive to ionic strength. The efficient cleavage mediated via hydrolytically cleaving pathway.Communicated by Ramaswamy H. Sarma.

Schiff Base Metal Complexes as Anticancer Agents

Cutting-edge practices in bioinorganic chemistry are pivotal for enhancing the layout of compounds to lessen poisonous facet effect and recognize their mechanism of action. A powerful anticancer agent should own inherent, inhibitory property and also delivery, dosage and residence time in vivo. Organic function and conformation of mutated gene may be altered by way of binding of metal ions. Upswing of activities counting on the structural data, intending in enhancing and growing different forms of metal based compounds, continuous seek of extra metal based compounds have been synthesized via revamping the prevailing chemical shape via ligand substitution. The prevailing paper addresses the trendy development in the design of novel antitumor agents primarily based on transition metal complex via highlighting the near dating among their structural alternatives and cytotoxic ability.

Biological evaluation of optically pure chiral binuclear copper(ii) complexes based on a rosin derivative as highly potential anticancer agents

An optically pure binuclear copper(ii) complex was prepared based on a rosin derivative, which is a DNA/BSA binder and a potential drug with multifunctional anticancer effects.

Schiff base complex conjugates of bovine serum albumin as artificial metalloenzymes for eco-friendly enantioselective sulfoxidation

Artificial metalloenzymes (BSA-ML) have been prepared by non-covalent insertion of transition metal Schiff-base complexes, ML (L = 2-hydroxynaphthalen-1-naphthaldehyde and 3,4-diaminobenzenesulfonic acid; M = Co, Mn, V, Fe, Cr), into bovine serum albumin (BSA) as the host protein and were characterized by UV-visible spectroscopy, ESI-TOF mass spectrometry and molecular docking studies. The catalytic activities of the BSA-ML in the selective oxidation of various prochiral sulfides in aqueous media, using H₂O₂ as oxidant, have been evaluated. During the optimization process, pH and the concentrations of catalyst and oxidant were found to have a remarkable influence on both yield and enantioselectivity. In certain cases, BSA-ML gave satisfactory results in the oxidation of organic sulfides to sulfoxides (up to 100% conversion, 100% chemoselectivity, 96% ee and 500 h⁻¹ turnover frequency).

Artificial metalloenzymes have been prepared by non-covalent insertion of transition metal Schiff-base complexes into bovine serum albumin as the host protein and were characterized by UV-visible spectroscopy, ESI-TOF mass spectrometry and molecular docking studies.

Synthesis, Structure, DNA Interaction, and SOD Activity of Three Nickel(II) Complexes Containing L-Phenylalanine Schiff Base and 1,10-Phenanthroline

Three hexacoordinated octahedral nickel(II) complexes, [Ni(sal-L-phe)(phen)(CH₃OH)]·CH₃OH (1), [Ni(naph-L-phe)(phen)(CH₃OH)] (2), and [Ni(o-van-L-phe)(phen)(CH₃OH)]·5CH₃OH (3) (sal-L-phe = a Schiff base derived from salicylaldehyde and L-phenylalanine, naph-L-phe = a Schiff base derived from 2-hydroxy-1-naphthaldehyde and L-phenylalanine, o-van-L-phe = a Schiff base derived from o-vanillin and L-phenylalanine, and phen = 1,10-phenanthroline), have been synthesized and characterized by elemental analysis, IR spectra, and single-crystal X-ray diffraction. The interactions of these complexes with CT-DNA were studied by UV-Vis absorption spectroscopy, fluorescence spectroscopy, circular dichroism spectroscopy, and viscosity measurements. The binding constant (K_b) values of 1.82 × 10⁴ M⁻¹ for 1, 1.96 × 10⁴ M⁻¹ for 2, and 2.02 × 10⁴ M⁻¹ for 3 suggest that each of these complexes could bind with DNA in a moderate intercalative mode. Complex 3 exhibited a stronger interaction with CT-DNA than complexes 1 and 2. In addition, the superoxide scavenging activity of these complexes was investigated by the nitrotetrazolium blue chloride (NBT) light reduction method, and the results showed that they exhibited a significant superoxide scavenging activity with the IC₅₀ values of 4.4 × 10⁻⁵ M for complex 1, 5.6 × 10⁻⁵ M for complex 2, and 3.1 × 10⁻⁵ M for complex 3, respectively.

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.