New non-toxic transition metal nanocomplexes and Zn complex-silica xerogel nanohybrid: Synthesis, spectral studies, antibacterial, and antitumor activities

Schiff Base-platinum and ruthenium complexes and anti-Alzheimer properties

This study investigates the effects of Pt and Ru complexes containing a Schiff base with a diimine structure on Alzheimer's disease. The Schiff base (N1E,N2E)-N1,N2-bis(isoquinolin-4-ylmethylene)benzene-1,2-diamine (I) and the novel Pt(II) and Ru(II) complexes (Ia and Ib) were synthesized and characterized using FTIR, NMR (1H, 13C), mass spectrometry, and elemental analyses. Their ability to inhibit amyloid beta (Aβ1-42) aggregation was determined in vitro using the SH-SY5Y cell line. Fluorescence spectroscopy investigated the early aggregation kinetics and dose-dependent characteristics of Aβ1-42 with the complexes. Transmission electron microscopy confirmed the results. Matrix-assisted laser desorption ionization-time of flight mass spectrometry (MALDI-TOF MS) and 1H NMR spectroscopy examined the interaction with Aβ1-16. Electrochemical analysis using square wave voltammetry monitored the interaction with Aβ1-42. The synthesized complexes were active in inhibiting amyloid aggregation at a low molar ratio.

Advances in Coordination Chemistry of Schiff Base Complexes: A Journey from Nanoarchitectonic Design to Biomedical Applications

Since the discovery of Schiff bases over one and a half centuries ago, there has been tremendous research activity in the design of various Schiff bases and examination of their diverse structures and versatile applications. This family of compounds has continued to captivate many research groups due to the simplicity of their synthesis through the condensation of amines with carbonyl compounds. While conventional synthesis has been the most widely used, green synthetic methodologies have been also explored for this reaction, including sonication, microwave-assisted, natural acid-catalyzed and mechanochemical syntheses as well as utilizing ionic liquid solvents or deep eutectic solvents. Schiff bases have been utilized as excellent ligands for coordination to transition metals and late transition metals (lanthanides and actinides). These Schiff base compounds can be mono-, di-, or polydentate ligands. The aim of this review is to examine the biological applications of Schiff base complexes over the past decade with particular focus on their antimicrobial, antiviral, anticancer, antidiabetic, and anti-inflammatory activity. Schiff base complexes have been found effective in combating bacterial and fungal infections with numerous examples in the literature. The review addressed this area by focusing on the very recent examples while using tables to summarize the vast breadth of research according to the metallic moieties. Viruses have continued to be a target of many researchers in light of their continuous mutations and impact on human health, and therefore some examples of Schiff base complexes with antiviral activity are described. Cancer continues to be among the leading causes of death worldwide. In this article, the use of Schiff base complexes for, and the mechanisms associated with, their anticancer activity are highlighted. The production of reactive oxygen species (ROS) or intercalation with DNA base pairs leading to cell cycle arrest were the main mechanisms described. While there have been some efforts made to use Schiff base complexes as antidiabetic or anti-inflammatory agents, there are limited examples when compared with antimicrobial and anticancer studies. The conclusion of this review highlights the emerging areas of research and future perspectives with an emphasis on the potential uses of Schiff bases in the treatment of infectious and noninfectious diseases.

Theoretical and experimental investigation of mixed-ligand metal(II) Schiff base complexes using maleic acid as the auxiliary ligand

This work is focused on the synthesis of several transition metal complexes [ML(MA)], where M = Copper (II), Zinc (II), Cobalt (II) and Nickel (II), MA = maleic acid and L = Schiff base generated from benzene-1,2-diamine [o-phenylenediamine] and 4-chlorobenzaldehyde. The characterization using Fourier-Transform Infrared, Nuclear Magnetic Resonance spectroscopy, Ultraviolet-Visible spectra, Mass, Electro Paramagnetic Resonance and elemental analysis confirm the square planar geometry of the complexes. The in vitro antimicrobial potential of the complexes has been tested by the broth dilution method and the antioxidant method has been done by free radical scavenging analysis. The in vitro methods reveal the outstanding biological characteristics of the copper complexes. The molecular structure of the ligand and its metal (II) complexes has been optimized using Density Functional Theory studies performed by the Gaussian-09 software and their parameters have been discussed. Natural Bond Orbital and Frontier Molecular Orbital analyses have assessed the presence of a metal-ligand bond in complexes. In addition, molecular docking studies have also been performed on antiviral activity of all the complexes using a viral protein and their interacting amino acids.

Advances in chromone-based copper(ii) Schiff base complexes: synthesis, characterization, and versatile applications in pharmacology and biomimetic catalysis

Chromones are well known as fundamental structural elements found in numerous natural compounds and medicinal substances. The Schiff bases of chromones have a much wider range of pharmacological applications such as antitumor, antioxidant, anti-HIV, antifungal, anti-inflammatory, and antimicrobial properties. A lot of research has been carried out on chromone-based copper(ii) Schiff-base complexes owing to their role in the organometallic domain and promise as potential bioactive cores. This review article is centered on copper(ii) Schiff-base complexes derived from chromones, highlighting their diverse range of pharmacological applications documented in the past decade, as well as the future research opportunities they offer.

Synthesis, characterization, DFT calculations and biological activity of new Schiff base complexes

Schiff bases ligand (HL) was produced by condensing 4-aminobenzohydrazide with N-(4-chlorophenyl)-2-(4-formylphenoxy)acetamide. Cobalt (II), nickel (II), and copper (II) acetate and ligand are reacted to form 1:1 complexes. By using electronic spectra, magnetic susceptibility measurements, infrared data from 1H NMR, and XRD studies, the ligand and its metal complexes have been characterized. According to the spectrum data, the ligand functions as a monobasic bidentate, coordinating with the nitrogen atom of azomethine (-C[bond, double bond]N-) group and the oxygen atom of carbonyl group in enol form. An octahedral structure has been proposed for Co(II), Ni(II), and Cu(II) complexes according to magnetic and electronic spectrum analysis. Using the DFT method, the computational investigations of the ligand and its metal complexes showed the bond lengths, bond angles, and quantum chemical parameters. To determine the thermal stability and mode of thermal degradation of hydrazone ligand and its complexes, thermogravimetric analysis was approved out on the samples. Two calculated method, Horowitz-Metzger and Coats-Redfern, were used to calculate the characteristics of the composites' thermal degradation mechanisms at each step, including their breakdown kinetics. The ligand and its complexes were investigated for their cytotoxicity in vitro compared to human amnion (WISH) and epitheliod carcinoma (Hela). The Ni(II) complex showed highly inhibition against (WISH) growth (IC50 = 18.28±1.8 μM) with relationship to the produced chemicals and other common medications. The interaction between the ligand and its complexes with the genetic tumor (3hb5) receptor was examined using docking experiments.

Pincer Complexes Derived from Tridentate Schiff Bases for Their Use as Antimicrobial Metallopharmaceuticals

Within the current challenges in medicinal chemistry, the development of new and better therapeutic agents effective against infectious diseases produced by bacteria, fungi, viruses, and parasites stands out. With chemotherapy as one of the main strategies against these diseases focusing on the administration of organic and inorganic drugs, the latter is generally based on the synergistic effect produced by the formation of metal complexes with biologically active organic compounds. In this sense, Schiff bases (SBs) represent and ideal ligand scaffold since they have demonstrated a broad spectrum of antitumor, antiviral, antimicrobial, and anti-inflammatory activities, among others. In addition, SBs are synthesized in an easy manner from one-step condensation reactions, being thus suitable for facile structural modifications, having the imine group as a coordination point found in most of their metal complexes, and promoting chelation when other donor atoms are three, four, or five bonds apart. However, despite the wide variety of metal complexes found in the literature using this type of ligands, only a handful of them include on their structures tridentate SBs ligands and their biological evaluation has been explored. Hence, this review summarizes the most important antimicrobial activity results reported this far for pincer-type complexes (main group and d-block) derived from SBs tridentate ligands.

Robust corrosion guard, mechanical and UV aging properties of metal complex/epoxy hybrid composite coating for C-steel applications

Incorporation of novel-prepared metal–organic complexes as crosslinking accelerators for multifunctional epoxy was on top of interest by coating formulators. The present work investigated the loading of mixed ligand metal complexes (Zr(IV) and Cu(II)) of metformin (MF) and 2.2′bipyridine (Bipy) against the free ligands as crosslinking modifiers via some epoxy coating formulations to assess their superb performances on the C-steel surface. Zr(IV) and Cu(II) demonstrated the minor energy gap (∆E) values at 0.190 au compared to free MF and Bipy according to the calculated energy values, and this behavior reflected their enhanced properties via epoxy coating applications. EIS measurements using high saline formation water as a corrosive medium were performed and offered that PA-DGEBA/MC-Cu coated film showed the superior resistance values (R_ct = 940 and R_c = 930 kΩ cm²). The accelerated corrosion salt spray experiment clarified that PA-DGEBA/MC-Cu coating achieved the least corrosion rate at 0.00049 mm/y and exhibited the highest protection efficiency of 99.84%. SEM/EDX combination survey affirmed the protective performance of the checked coatings. AFM microanalysis confirmed that surface-treated Cu(II) coating displayed the smoothest film surface with complete curing. Mechanical durability properties were evaluated and the obtained results illustrated that pull-off adhesion for PA-DGEBA/MC-Cu coated film fulfilled the highest adhesion strength at 6.3 MPa, the best bend character at 77, and the maximum impact resistance at 59.7 J. UV immovability trial was performed at 10 irradiance and 80 h duration. PA-DGEBA/MC-Cu coated film displayed the highest resistance to UV irradiance with blistering (#8 size and few frequencies) in addition to offering a minor gloss variation and matt properties.

In vivo Study of a Newly Synthesized Chromen-4-one Derivative as an Antitumor Agent against HCC

BACKGROUND

Chromenes are a wide group of natural compounds that can be synthesized chemically. The chromen-4-one nucleus acts as a skeleton for varieties of additional active groups that makes the chromene activity vary between antioxidant and anti-inflammatory agents. In the present study, a newly synthesized chromene compound exhibits different behaviors other than anti-inflammatory and antioxidant activities that it is the first time that a member of chromen-4-one compound can control the cancer progress. Inflammation is the first step in tumor development where the severity grade can potentiate tumor growth and progression. In many tumors, pro-inflammatory genes record high expression level such as tumor necrosis factor (TNF-α) and vascular endothelial growth factors (VEGF). These pro-inflammatory factors act as rate limiting steps in tumor initiation, and controlling its expression acts as an early therapeutic way to control the tumor proliferation. The chromone derivatives have biological activities such as anti-inflammatory and anti-tumor activity.

METHODS

In the present study, hepatocellular cancer (HCC) induced by diethylnitrosamine (DEN) in rats and then treated with the new chromene derivative and the parameters TNF-α, VEGF, p53, Cyt C, MMP-9, Bcl2, and Bax were measured.

RESULTS

The treatment strategy Ch compound is to downregulate pro-inflammatory gene expression of early genes as TNF-α as well as VEGF and subsequently control other factors such as p53, Cyt C, and MMP-9. Also, retrieve the balance between Bcl2 and Bax proteins in DEN-induced HCC in rats.

CONCLUSION

The ability of the new Ch derivative to control the primary initiators of HCC such as TNF-α offers this derivative an anti-tumor activity and encourages further researches to follow and monitor its effect on the molecular level.

Modulatory effect of a new benzopyran derivative via COX-2 blocking and down regulation of NF-κB against γ-radiation induced- intestinal inflammation

Radiotherapy is considered as a primary modality for cancer treatment which accompanied by several side effects. Protection of normal tissues from radiation effects is one of the most significant concerns for researchers. Although many compounds acting as radio protectors, only two compounds were licensed clinically. Cyclooxygenase-2 (COX-2), as an inflammatory mediator is associated with ROS production with a NF-κB gene up regulation dependent manner in normal tissues. To that extend, his study was designed to target COX-2 and NF-κB by a newly synthesized benzopyran-4-one or chromone derivative; (2E)-2-((4-oxo-4H-chromen-3-yl) methylene amino-4- nitrobenzoic acid (Ch). Exposure of mice to IRR significantly induced intestinal inflammation via overexpression of COX-2 and NF-κB which is accompanied by an increase in the levels of MDA and iNOS in tissue homogenate and in the production of TNF-α and IL-6 as inflammatory signs. Moreover, the apoptotic effect of IRR was manifested by obvious elevation in caspase-3. Interapretonial injection of Ch significantly controls the inflammatory response by blocking the COX-2 and decrease the expression NF-κB which subsequently decreases other inflammatory parameters. Thus Ch compound might be a promising nonsteroidal anti-inflammatory drug (NSAID) against radiation-induced inflammation with a specific mode of COX-2 inhibition. Further researches are needed to elucidate its molecular mechanism and its combination with radiotherapy as a protector.

Anticancer activities of a β-amino alcohol ligand and nanoparticles of its copper(ii) and zinc(ii) complexes evaluated by experimental and theoretical methods

2-(2-(2-Hydroxyethylamino)ethylamino)cyclohexanol (HEAC) and copper and zinc complexes, [Cu(HEAC)Cl]Cl (1), [Cu(HEAC)Br]Br (2), [Zn(HEAC)Cl₂] (3), were prepared and identified by elemental analysis, FT-IR, UV-Vis, ¹H NMR spectroscopy and single-crystal X-ray diffraction. Also nanoparticles of 1–3 were prepared for anticancer studies by ultrasonic irradiation. Particle size and morphology of the nano particles are investigated by PXRD and SEM, respectively. X-ray analysis revealed that the ionic complexes 1 and 2 are isostructural. In the structure of complexes 1 and 2, the metal atom has a CuN₂O₂X (X: Cl (1), Br (2)) environment with square-pyramidal geometry, containing the tetradentate N₂O₂-donor HEAC. The bond length of the axial position in the square-pyramidal geometry of 1 and 2 is elongated. Complex 3 has a ZnN₂OCl₂ environment with trigonal bipyramidal geometry around the zinc atom in which the HEAC acts as mer-N₂O-donor. The ability of HEAC and nano particles 1–3 to interact with the nine biomacromolecules (BRAF kinase, CatB, DNA gyrase, HDAC7, rHA, RNR, TrxR, TS and Top II) are investigated by docking calculations. For examination of the docking results, the in vitro activities of four compounds against the human leukemia cell line K562 were investigated by evaluation of IC₅₀ values and mode of cell death (apoptosis). The thermodynamic stability of the compounds along with the charge distribution pattern were studied by DFT and NBO analysis, respectively.

Nano particles of copper and zinc complexes with an amino alcohol ligand were prepared under ultrasonic irradiation and their anticancer activates were investigated along with the docking studies and DFT calculations.