Synthesis, spectroscopic characterization and biological applications of some novel Schiff base transition metal (II) complexes derived from curcumin moiety

Synthesis, theoretical analysis, and biological properties of a novel tridentate Schiff base palladium (II) complex

Schiff base complexes play a crucial role in bioinorganic chemistry. A novel curcumin/phenylalanine tridentate Schiff base ligand and its palladium (II) complex were synthesized so that they were stable in aqueous buffer. The structure of the complex was investigated using a variety of methods, including DFT, NBO analysis, FMOs, and MESP. The interaction of the complex with a plasmid (pUC19) and CT-DNA was studied. The anticancer, antibacterial, and antioxidant activities of the complex were examined. The statistical analysis of the MTT assay was compared using the 1-way ANOVA and Tukey test. Results showed that the complexes were stable in aqueous buffer, pH 8. The extrinsic fluorescence emission of the plasmid and CT-DNA was quenched while interacting with the complex. The complex had an IC50 of 72.47 µM against MCF-7 cells. The ANOVA and Tukey analysis of MTT data demonstrated a statistically significant difference between groups (P < 0.0001). The minimum inhibitory concentrations (MIC) of the complex for E. coli and S. aureus were 300 and 200 µg/mL, with 96.3 and 95.2% biofilm growth inhibition at 250 µg/mL, respectively. The sample concentrations contributing to 50% radical inhibition in the 1,1-diphenyl-2-picrylhydrazyl (DPPH) test for curcumin, ligand, and palladium (II) complex were 33.62, 21.27, and 51.26 µM, respectively. The results suggest that the complex interaction with DNA is one of the potential mechanisms for eliminating cancer cells and bacteria in the planktonic and biofilm. On the other hand, while stability in an aqueous buffer at pH 8 increases, the modified curcumin antioxidant effect decreases.

Pharmaceutical manifestation of Knoevenagel condensed metal (II) complexes through virtual, in vitro and in vivo assessments

Sulphur containing compounds possess a great deal of interest due to wide range of beneficial activities towards biotic species. This work also deals with the study of biological examination of newly synthesized sulphur containing Cu(II) and Zn(II) complexes derived from (E)-4-(phenylimino)-3-((E)-1-(phenylimino)ethyl)pent-2-ene-1-thiol Schiff bases. Moreover, the DNA nuclease efficiency of the synthesized metal complexes is studied by UV absorption studies, Fluorescence studies, Viscosity and CV titrations which confirm the intercalative mode of binding. Pharmacokinetic studies and drug like activity of these compounds are screened with the help of SWISS ADME online freeware. Their morphological nature is corroborated by various spectral techniques. Optimized geometry and biologically accessible nature of the synthesized compounds are investigated by Gaussian 09 W software. Interestingly, molecular docking studies are carried out against cancer DNA and 6J10 cancer cell. Anti-inflammatory and in vitro antioxidant activities have been studied to validate the theoretical prediction. Based on these preliminary pharmacological activities, the in vitro cytotoxicity and in vivo antitumor activities are examined using MCF-7, HeLa, Hep-2, HepG-2 and Ehrlich ascites carcinoma (EAC) cell lines. All the above examinations reveal that the nitro substituted transition metal complexes possess higher biological bustle.Communicated by Ramaswamy H. Sarma.

Flexible and sewable electrode based on Ni-Co@PANI-salphen composite-coated on textiles for wearable supercapacitor

Flexible electrodes with high deformability and energy density are critical for electronic textiles. The key factor for achieving high-performance supercapacitors with superior power and energy density is the evaluation of materials that exhibit exceptional capacitive performance. Herein, we have prepared Ni-Co nanoparticles at the surface of polyaniline-salphen (Ni-Co@PS). Then, followed by casting Ni-Co@PS on a conductive carbon cloth (CC) as a substrate through a facile in-situ polymerization strategy. The morphologies of Ni-Co@PS composite were characterized by different methods such as FE-SEM, XPS, XRD, BET, and electrochemical methods. This nanocomposite showed high tolerability and a large surface area with excellent behavior as a new nanomaterial for supercapacitor application. Thus, the optimum composite designed with a metal ratio (nickel-cobalt 3:1 w/w) satisfactorily possesses a specific capacitance of up to 549.994 C g-1 (1447.2 F g-1) under 0.5 A g-1 and long-term cyclic stability featuring capacity retention of 95.9% after 5000 cycles at a current density of 9.0 A g-1. The Ni-Co@PS-CC, is a material with great potential as an electrode in asymmetric wearable supercapacitor (AWSC) apparatus, demonstrating a remarkable specific capacity of 70.01, and accompanied by an energy density of 23.46 Wh k g-1 at a power density of 800 W k g-1.

Biological and computational investigation of transition metal(II) complexes of 2-phenoxyaniline-based ligands

Aim: In the 21st century, we are witness of continuous onslaughts of various pathogen deformities which are a major cause of morbidity and mortality worldwide. Therefore, to investigate the grave for these deformities, antioxidant, anti-inflammatory and antimicrobial biological activities were carried out against newly synthesized Schiff base ligands and their transition metal complexes, which are based on newly synthesized 2-phenoxyaniline and salicylaldehyde derivatives. Materials & methods: The synthesized compounds were characterized by various physiochemical studies, demonstrating the octahedral stereochemistry of the complexes. Results: The biological assessments revealed that complex 6 (3.01 ± 0.01 μM) was found to be highly active for oxidant ailments whereas complex 14 (7.14 ± 0.05 μM, 0.0041-0.0082 μmol/ml) was observed as highly potent for inflammation and microbial diseases. Conclusion: Overall, the biological and computational studies demonstrate that the nickel(II) complex 14 can act as an excellent candidate for pathogen deformities.

Novel Schiff Base Derived from Amino Pyrene: Synthesis, Characterization, Crystal Structure Determination, and Anticancer Applications of the Ligand and Its Metal Complexes

In this study, we report the cytotoxicity of a newly synthesized Schiff base HL ((E)-2-ethoxy-6((pyren-1-ylimino)methyl)phenol) and its derived metal complexes (Zn(II), Cu(II), Co(II), Cr(III), and Fe(III)) along with their structural characterizations by means of elemental analysis, magnetic moment, molar conductance, IR, UV-Vis, ESR, and mass spectrometry. The single X-ray diffraction of the HL shows that it exists in the phenol-imine form in its solid state. The NMR and IR data indicate that the bidentate binding of the Schiff base ligand with the metal center occurs during complexation through the azomethine nitrogen atom and the hydroxyl group oxygen atom of the 3-ethoxy salicylaldehyde. The electronic spectra and magnetic measurements indicate that the Co(II) complex has a tetrahedral geometry and that the Cr(III) and Fe(III) complexes have a distorted octahedral geometry. The ESR and electronic spectra suggest that the Cu(II) complex has a distorted tetrahedral geometry. The cytotoxic effects of the HL and all of the metal complexes were studied using human breast cancer (MCF-7) cells. The Cu(II) and Zn(II) complexes exhibited the highest activity against the tested cell line, with IC50 values of 5.66 and 12.74 μg/mL, respectively, and their activity was higher than that of the fluorouracil cancer drug against the MCF-7 cells (18.05 μg/mL).

A Nanomedicine-Enabled Ion-Exchange Strategy for Enhancing Curcumin-Based Rheumatoid Arthritis Therapy

Curcumin (Cur) has been clinically used for rheumatoid arthritis treatment by the means of reactive oxygen species (ROS) scavenging and immune microenvironment regulation. However, this compound has a poor water solubility and moderate antioxidative activity, favoring no further broadened application. Metal complexes of curcumin such as zinc-curcumin (Zn-Cur) features enhanced water solubilities, while copper-curcumin (Cu-Cur) shows a higher antioxidant activity but lower solubility than Zn-Cur. Based on their inherent biological properties, this work proposes a nanomedicine-based ion-exchange strategy to enhance the efficacy of Cur for rheumatoid arthritis treatment. Copper silicate nanoparticles with hollow mesoporous structure were prepared to load water-soluble Zn-Cur for constructing a composite nanomedicine, which can degrade in acidic microenvironment of arthritic region, releasing Cu2+ and Zn-Cur. Cu2+ then substitute for Zn2+ in Zn-Cur to form Cu-Cur with a significantly enhanced antioxidative effect, capable of efficiently scavenging ROS in M1 macrophages, promoting their transition to an anti-inflammatory M2 phenotype. In addition, the silicate released after nanocarrier degradation and the Zn2+ released after ion exchange reaction synergistically promote the biomineralization of osteoblasts. This work provides a new approach for enhancing the antiarthritic effect of Cur via an ion-exchange strategy.

Novel palladium(II) and Zinc(II) Schiff base complexes: Synthesis, biophysical studies, and anticancer activity investigation

BACKGROUND

Schiff base metal complexes are considered promising chemotherapeutic agents due to their potential application in cancer therapy.

METHODS

The current work sought to synthesize a brand-new Schiff base ligand obtained from 2-hydroxybenzohydrazide and (E)- 1-(2-(p-tolyl)hydrazono)propan-2-one with metal ions which included Pd(II) and Zn(II) ions. Elemental analyses, FT-IR, mass spectra, 1H NMR, UV-Vis spectrometer, and computational analysis characterized the compound's structure. In vitro, the breast cancer cell line (MCF-7) was tested for its sensitivity to Schiff base (HL) and its Pd(II) and Zn(II) complexes. The half-maximal inhibitory concentration IC₅₀ of the compounds was determined and used to perform the comet assay, which was carried out to reveal the photo-induced DNA damaging ability of the compounds of individual cells. Moreover, the compounds' effects on antioxidant defense systems of enzymes in cells: superoxide dismutase (SOD), catalase (CAT), and glutathione peroxidase (GPx) activities and oxidant Malondialdehyde (MDA) were examined in MCF-7 cells.

RESULTS

The Pd(II) complex displayed approximately the same IC₅₀ as Cisplatin, while Zn(II) complex had better activity than Cisplatin with very low IC₅₀, 1.40 μg/ml. Significant alterations in SOD, CAT, GPx, and MDA production were discovered, inducing oxidative stress, enlarging ROS production, and reducing the antioxidant amount. This change was approximately similar in most compounds. Consequently, it promoted apoptosis, particularly the Zn(II) complex, which demonstrated an improved impact because of its ability to influence the antioxidant defense systems of enzymes, mostly SOD and GPx, besides increasing MDA levels.

CONCLUSION

It can be concluded that Zn(II) complex is the most effective anticancer drug since it induced a very similar genotoxic effect as Cisplatin and has a very low IC₅₀ value.

Metal Complexes with Schiff Bases: Data Collection and Recent Studies on Biological Activities

Metal complexes play a crucial role in pharmaceutical sciences owing to their wide and significant activities. Schiff bases (SBs) are multifaceted pharmacophores capable of forming chelating complexes with various metals in different oxidation states. Complexes with SBs are extensively studied for their numerous advantages, including low cost and simple synthetic strategies. They have been reported to possess a variety of biological activities, including antimicrobial, anticancer, antioxidant, antimalarial, analgesic, antiviral, antipyretic, and antidiabetic ones. This review summarizes the most recent studies on the antimicrobial and antiproliferative activities of SBs-metal complexes. Moreover, recent studies regarding mononuclear and binuclear complexes with SBs are described, including antioxidant, antidiabetic, antimalarial, antileishmanial, anti-Alzheimer, and catecholase activities.

Synergism antibacterial activity for novel synthesized Schiff base ligands and semi-thiosemicarbazones with ß-diketones and 4-aminoantipyrine

Schiff base ligands were synthesised in this work, the first is (Z)-2-((Z)-3-((1,5-dimethyl-3-oxo-2-phenyl-2,3-dihydro-1H-pyrazol-4-yl)imino)-1,3-diphenylpropylidene) hydrazine-1-carboxamide, the second is (Z)-2-((1E,5Z,6E)-5-((1,5-dimethyl-3-oxo-2-phenyl-2,3-dihydro-1H-pyrazol-4-yl)imino)-1,7-bis(4-hydroxy-3-methoxyphenyl)hepta-1,6-dien-3-ylidene)hydrazine-1-carbothioamide. The Schiff base ligands both were synthesised using the same method (the single pot reaction), using EtOH as the reaction medium and GAA as the catalyst in fixed temperature at 70 0C and reflux for 6 hrs. The starting materials of HL1 were semicarbazide,4-aminoantipyrine and dibenzoyl methane, while the starting materials of HL2 were TSC, 4-AAP and Curcumin. The ligands proved to be bi-dentate ligands that coordinate from the azomethane groups. FT-IR, U.V-Visible, 1H and 13C- NMR, molar conductivity, and magnetic susceptibility were used to identify all the compounds produced. The metal ions used in preparing the complexes in this work were Co(II), Cu(II) and Cr(III). Schiff base and its complexes were evaluated for antibacterial activity against four bacterial strains of Gram-negative (Escherichia coli and Pseudomonas aeruginosa), Gram-positive (Staphylococcus aureus and Bacillus Subtilis) and two types of fungi (Candida albicans and Rhizopus Sporium), the results were positive for all compounds tested. Keywords: Schiff base, Curcumin, 4-aminoantipyrine

Synthesis, characterization, in vitro, in silico and in vivo investigations and biological assessment of Knoevenagel condensate β-diketone Schiff base transition metal complexes

A novel Schiff base ligand was synthesized by the Knoevenagel condensation of β-diketone (obtained from substituted Curcumin and Cuminaldehyde) and 4-amino antipyrine. Metal complexes were made from this Schiff base by reacting with metal salts such as Cu(II), Ni(II), Ru(III), VO(IV), and Ce(IV). Physicochemical approaches such as UV-Vis, FT-IR, NMR, EPR, and Mass spectroscopy were used to determine the geometry of the complexes. The thermodynamic stability and biological accessibility of the complexes were investigated using density functional theory (DFT) calculations at the B3LYP/6-31G(d) level. A molecular docking analysis was also performed on 1BNA receptor. Both the Schiff base ligand and metal complexes interacted well to this protein receptor. All metal complexes have a significant potential to bind to CT DNA via the intercalation mechanism. All the in vivo and in vitro screening studies showed that the complexes exhibit higher activities than the free Schiff base.Communicated by Ramaswamy H. Sarma.

Innovative Bacterial Removal Technique Using Green Synthetic Nano Curcumin Zinc (II) Complex for Sustainable Water Resource Management

Sustainable management of water resources is a daunting challenge, especially with respect to microbes. This study primarily focused on the development of a novel application for the removal of specific bacterial groups in different water types using a green synthetic nano Cur-Zn(II) complex. The results of UV and FT-IR spectroscopic techniques suggested the formation of a chelation complex. Proton NMR showed that the main enolic proton peak with a chemical shift of 16.45 nm identified in curcumin was missed, indicating the contribution of carbonyl oxygen of enol in the formation of the complex. The crystalline nature of the complex and Wurtzite structure of annealed products was inferred from the XRD analysis data. SEM results confirmed the complex’s morphology as spherical and clustered with a rough surface, having an average particle size of 68.2 nm. In addition, the complex was observed to be stable up to 300 °C without any decomposition from STA. Being acidic in nature with a pH of 5.36, the complex penetrates into the cell membrane and inhibit microbial growth. Intrinsically, no studies have been reported for the removal of microbes from water using natural materials embedded with inorganic metals, particularly in nano form. Therefore, the study is the first, innovative, eco-friendly, and economical method to use nano Cur-Zn(II) for removing targeted bacteria in real water samples with 100% efficiency by using optimized amounts (0.025–0.2 g/L) of the complex at a contact time interval between 4 and 24 h. The complex developed is toxic-free and can be applied in situ.