A robust in vitro Anticancer, Antioxidant and Antimicrobial Agents Based on New Metal‐Azomethine Chelates Incorporating Ag(I), Pd (II) and VO (II) Cations: Probing the Aspects of DNA Interaction

Metal complexes of Schiff bases synthesized from condensation of an amine with carbonyl compounds are widely used for industrial purposes such as catalysts, pigments and dyes, intermediates in orga...

REVIEW: Biomedical applications of Schiff base metal complexes

Synthesis, characterization of Schiff base metal complexes and their biological investigation

Antimicrobial resistance is an increasingly serious threat to global public health that requires innovative solutions to counteract new resistance mechanisms emerging and spreading globally in infectious pathogens. Classic organic antibiotics are rapidly exhausting the structural variations available for an effective antimicrobial drug and new compounds emerging from the industrial pharmaceutical pipeline will likely have a short-term and limited impact before the pathogens can adapt. Inorganic and organometallic complexes offer the opportunity to discover and develop new active antimicrobial agents by exploiting their wide range of three-dimensional geometries and virtually infinite design possibilities that can affect their substitution kinetics, charge, lipophilicity, biological targets and modes of action. This review describes recent studies on the antimicrobial activity of transition metal complexes of groups 6–12. It focuses on the effectiveness of the metal complexes in relation to the rich structural chemical variations of the same. The aim is to provide a short vade mecum for the readers interested in the subject that can complement other reviews.

https://www.mdpi.com/2624-8549/2/2/26/pdf

Recent Studies on the Antimicrobial Activity of Transition Metal Complexes of Groups 6–12

Background Schiff bases and their metal complexes are emerging as key classes of medicinal compounds, possessing an enormous potential of biological activities like anticancer, anticonvulsant and antioxidant etc. The aim of this review is to examine the anticancer activity of different classes of Schiff bases and their metal complexes. Methods Anticancer activity of the already synthesized as well as the novel Schiff bases and their metal complexes was studied using different assays such as 3- [4,5-dimethyltiazol-2-yl]-2,5-diphenyl-tetrazolium bromide (MTT), PI staining, Sulforhodamine, Allium cepa, Sulfo- Rhodamine-B-stain(SRB), viability and potato disc against various human and animal cancer cell lines. Results The test results indicated significant differences in anticancer activity between subclasses of Schiff base compounds as well as between the Schiff base ligands and their metal complexes. Quinazolines showed a very high activity against HepG2 and MCF-7 cell lines. Pyrazole-naphthalene derivatives exhibited high activity against numerous carcinoma cells while [Ni(HL1)2(OAc)2] showed the highest. Azosal and its tin(IV) complexes displayed high activity against U-1242 MG and excellent activity against HCT-116 cell lines. 2-thiouracil sulfonamides displayed high activity against MCF7, CaCo-2 carcinoma cells. Vitamin-B6 and its oxovanadium complex showed good activity against MCF-7, 3T3 and cervical cancer HeLa cancer cell lines in the presence of visible light. Indoles displayed high activity against AMJ13. Porphyrines derivatives exhibited good activity while its binuclear(Y and K) complexes displayed high activity against several carcinoma cells. Chitosan complexes of [Pd(II) and Pt(II)] showed a very high anticancer activity against MCF-7 carcinoma cell. Conclusion Schiff bases possess a high potential to inhibit carcinoma cells which enhanced with complexation, but the mechanism of their antitumor activity is still doubt.

Schiff Bases and their Metal Complexes as Potential Anticancer Candidates: A Review of Recent Works.

A novel Schiff base ligand (H2L) was prepared through condensation of 2,6-diaminopyridine and o-benzoylbenzoic acid in a 1:2 ratio. This Schiff base ligand was characterized using elemental and spectroscopic analyses. A new series of Cr(III), Mn(II), Fe(III), Co(II), Ni(II), Cu(II), Zn(II) and Cd(II) metal complexes of H2L were prepared and characterized using elemental analysis, spectroscopy (1H NMR, mass, UV–visible, Fourier transform infrared, electron spin resonance), magnetic susceptibility, molar conductivity, X-ray powder diffraction and thermal analysis. The complexes are found to have trigonal bipyramidal geometry except Cr(III), Mn(II) and Fe(III) complexes which have octahedral geometry based on magnetic moment and solid reflectance measurements. The infrared spectral studies reveal that H2L behaves as a neutral bidentate ligand and coordinates to the metal ions via the two azomethine nitrogens. 1H NMR spectra confirm the non-involvement of the carboxylic COOH proton in complex formation. The presence of water molecules in all reported complexes is supported by thermogravimetric studies. Kinetic and thermodynamic parameters were determined using Coats–Redfern and Horowitz–Metzger equations. The synthesized ligand and its complexes were screened for antimicrobial activities against two Gram-positive bacteria (Bacillus subtilis and Staphylococcus aureus), two Gram-negative bacteria (Escherichia coli and Neisseria gonorrhoeae) and one fungus (Candida albicans). Anticancer activities of the ligand and its metal complexes against human breast cancer cell line (MCF7) were investigated. Copyright © 2016 John Wiley & Sons, Ltd.

Novel Schiff base ligand and its metal complexes with some transition elements. Synthesis, spectroscopic, thermal analysis, antimicrobial and in vitro anticancer activity

The condensation of o-benzoyl benzoic acid and 4-aminoantipyrine resulted in the formation of novel Schiff base ligand (HL) with the IUPAC name 2-(((1,5-dimethyl-3-oxo-2-phenyl-2,3-dihydro-1H-pyrazol-4-yl)imino)(phenyl)methyl)benzoic acid. The synthesized Schiff base ligand and its complexes with M(II)/(III) transition elements (Cr(III), Mn(II), Fe(III), Co(II), Ni(II), Cu(II), Zn(II) and Cd(II)) were characterized by elemental, magnetic susceptibility, molar conductivity, spectroscopic (1H NMR, mass, UV–visible, FTIR, ESR), thermal and X-ray powder diffraction. The data showed that the complexes had composition of the MHL type. The diffused reflectance spectra, magnetic susceptibility and ESR spectral data of the complexes confirm an octahedral geometry around metal ions. The thermal analysis data revealed the decomposition of the complexes in three to five successive decomposition steps within the temperature range of 30–1000°C, and the activation thermodynamic parameters were reported. The molecular structures of the Schiff base ligand and its Mn(II) and Zn(II) metal complexes are optimized theoretically, and the quantum chemical parameters are calculated. In order to predict the binding between o-benzoyl benzoic acid, 4-aminoantipyrine and HL ligand with the Escherichia coli bacterial RNA (4p20) receptor, molecular docking was carried out. The in vitro antimicrobial screening of the newly synthesized compounds was tested against different bacterial and fungal organisms. The results showed that the metal complexes have biologically activity more than the new Schiff base ligand against the tested organisms. The Schiff base ligand and its complexes were also screened for their anticancer activity against breast cancer cell line (MCF7). The Mn(II), Cr(III) and Cd(II) complexes were found to have low IC50 values which support the possibility of using them as cytotoxic agents and hence might become good anticancer agent in clinical trials.

Preparation, geometric structure, molecular docking thermal and spectroscopic characterization of novel Schiff base ligand and its metal chelates

Appl Organometal Chem. 2018;e4556. https://doi.org/10.1002/aoc.4556 An organometallic NO‐bidentate Schiff base, (2‐(1‐((1‐carboxyethyl)imino) ethyl) cyclopenta‐2,4‐dien‐1‐yl)(cyclopenta‐2,4‐dien‐1‐yl) iron (HL) was synthesized by condensation of 2‐acetylferrocene with amino acid alanine. Then its octahedral Cr (III), Mn (II), Fe (III), Co (II), Ni (II), Cu (II), Zn (II) and Cd (II) complexes were synthesized. All compounds were characterized on the basis of elemental analysis (C, H, N and M), molar conductivity, FT‐IR, UV–Vis, H‐NMR, SEM, mass analysis and thermal studies. Furthermore, computational studies of HL ligand have been carried out by DFT/B3LYP method. HOMO and LUMO energy values, chemical hardness‐softness, electronegativity, electrophilic index and other parameters were calculated. SEM micrographs of HL ligand and its [Cd (HL)(H2O)2Cl2].2H2O complex, showed that they were prepared in nano‐structure forms with particle size 54 and 41 nm, respectively. Antifungal and antibacterial activities of HL ligand and its metal complexes have been screened in vitro against different species such as Aspergillus fumigatus, Candida albicans, Bacillus subtilis, Staphylococcus aureus, Escherichia coli and Salmonella typhimurium. The synthesized compounds were evaluated for their anticancer activities against breast cancer cell line (MCF‐7) and normal melanocytes cell line (HFB‐4). It was found that [Co (HL)(H2O)2Cl2].3H2O complex had the lowest IC50 value (10.9 μg/ml) and hence was the most active one. Finally, the optimized structures of the Schiff base and its Co (II) complex have been used to accomplish molecular docking studies with receptors of 3HB5, 3MIW, 5IBV and 4WM8 to determine the most preferred mode of interaction.

Transition metal complexes of nano bidentate organometallic Schiff base: Preparation, structure characterization, biological activity, DFT and molecular docking studies

Metal complexes of ferrocenyl-substituted Schiff base: Preparation, characterization, molecular structure, molecular docking studies, and biological investigation

Appl Organometal Chem. 2018;e4289. https://doi.org/10.1002/aoc.4289 The condensation of 2‐acetylferrocene with 4‐nitro‐1,2‐phenylenediamine in a 1:1molar ratio, resulting in formation of a novel bi‐dentate organometallic Schiff base ligand (L), (2‐(1‐((2‐amino‐5‐nitrophenyl)imino)ethyl)cyclopenta‐2,4‐dien‐ 1‐yl)(cyclopenta‐2,4‐dien‐1‐yl)iron. Also, its Cr(III), Mn(II), Fe(III), Co(II), Ni(II), Cu(II), Zn(II) and Cd(II) complexes have been synthesized. The stoichiometric ratios of the prepared compounds were estimated using elemental analysis (C, H, N, M), molar conductivity, FT‐IR, UV‐Vis, H‐NMR, SEM and mass spectral analysis. Furthermore, their TG and DTG properties were studied. The geometrical structure of the complexes was found to be octahedral. From spectral analysis, the Schiff base coordinated to metal ions through the azomethine and amine groups. DFT‐based molecular orbital energy calculations of the synthesized ligand have been studied, in which the ligand was theoretically optimized. The Schiff base and its metal complexes have been screened for their antimicrobial activities against different bacterial and fungal species by using disc diffusion method. The anticancer activities of the ligand and its metal complexes have also been studied towards breast cancer (MCF‐7) and human normal melanocytes (HFB‐4) cell lines. Molecular docking was also used to identify the interaction between the Schiff base ligand and its Cd(II) complex with the active site of the receptors of breast cancer mutant oxidoreductase (PDB ID: 3HB5), crystal structure of Staphylococcus aureus (PDB ID: 3Q8U) and yeast‐specific serine/threonine protein phosphatase (PPZ1) of Candida albicans (PDB ID:5JPE).

Metal complexes of novel Schiff base derived from iron sandwiched organometallic and 4-nitro-1,2-phenylenediamine: Synthesis, characterization, DFT studies, antimicrobial activities and molecular docking

Gehad G. Mohamed

Papers

Novel Schiff base ligand and its metal complexes with some transition elements. Synthesis, spectroscopic, thermal analysis, antimicrobial and in vitro anticancer activity

Preparation, geometric structure, molecular docking thermal and spectroscopic characterization of novel Schiff base ligand and its metal chelates

Transition metal complexes of nano bidentate organometallic Schiff base: Preparation, structure characterization, biological activity, DFT and molecular docking studies

Metal complexes of ferrocenyl-substituted Schiff base: Preparation, characterization, molecular structure, molecular docking studies, and biological investigation

Metal complexes of novel Schiff base derived from iron sandwiched organometallic and 4-nitro-1,2-phenylenediamine: Synthesis, characterization, DFT studies, antimicrobial activities and molecular docking