Spectrophotometric determination of Zr(IV), Hg(II) and U(VI) in solution with their analytical applications: Structural characterization and molecular docking of the solid complexes

Antimicrobial Activity of Novel Ni(II) and Zn(II) Complexes with (E)-2-((5-Bromothiazol-2-yl)imino)methyl)phenol Ligand: Synthesis, Characterization and Molecular Docking Studies

In order to address the challenges associated with antibiotic resistance by bacteria, two new complexes, Ni(II) and Zn(II), have been synthesized using the conventional method based on Schiff base ligand (E)-2-((5-bromothiazol-2-yl) imino) methyl) phenol. The Schiff base ligand (HL) was synthesized using salicylaldehyde and 5-(4-bromophenyl)thiazol-2-amine in both traditional and efficient, ecologically friendly, microwave-assisted procedures. The ligand and its complexes were evaluated by elemental analyses, FTIR spectroscopy, UV-Vis spectroscopy, nuclear magnetic resonance (NMR), thermogravimetric analysis (TGA) and magnetic susceptibility. The ligand and its complexes were tested for antibacterial activity against three Gram-positive bacteria (Staphylococcus aureus ATCC 25923, Methicillin-resistant Staphylococcus aureus ATCC 43300 and Enterococcus faecalis ATCC 29212) and three Gram-negative bacteria (Pseudomonas aeruginosa ATCC 27853, Escherichia coli ATCC 25922 and Klebsiella pneumoniae ATCC 700603). The findings demonstrate the potent activity of the ligand and its complexes against selective bacteria but the Ni(II) complex with MIC values ranging from 1.95 to 7.81 µg/mL outperformed all other compounds, including the widely used antibiotic Streptomycin. Furthermore, the docking study provided evidence supporting the validity of the antimicrobial results, since the Ni complex showed superior binding affinity against to E. coli NAD synthetase, which had a docking score (-7.61 kcal/mol).

Novel Hybrid Triazoline - Triazole Glycosides: Synthesis, Characterization, Antimicrobial Activity study via In Vitro, and In Silico Means

Series of novel 1,2,3-triazole, and 1,2,3- triazoline glycosides (a-e) were efficiently synthesized starting from d-arabinose in an effort to synthesize a new type of hybrid molecules containing sugar azide. The key step involved is the introduction of a new group, ethylene glycol, to the anomeric site and protection of the hydroxyl groups with acetic anhydride. Following that, the acetyl group is converted into ethylene glycol to tosylate. Compound Azido ethyl-O-β-d-arabinofuranoside 4 was synthesized with good yield by treating the derivative 3 with sodium azide, which displaced the tosylate 3 and replaced it with the azide group. The new glycosides were synthesized via a 1,3-dipolar cycloaddition reaction between the intermediate compound 4 and several alkenes and alkynes. The triazole and triazoline compounds were characterized by FT-IR, 1H NMR, 13C NMR, LC/MS-IT-TOF spectral, and C·H.N. analysis. The antimicrobial screening was assayed using the disc diffusion technique revealed moderate to high potential inhibitory values against three test microorganisms compared to standard drugs. Their pharmacokinetics evaluation also showed promising drug-likeness and ADME properties. Furthermore, density functional theory (DFT) was utilized to obtain the molecular geometry of the title compounds utilizing B3LYP/6-311G++ (d, p), molecular electrostatic potential (MEP), frontier molecular orbitals (FMOs) through the investigation of HOMO and LUMO orbitals, and energy gap value. A lower energy gap value denotes that electrons can be transported more easily, indicating that molecule (b) is more reactive than other compounds. Molecular docking analysis revealed that all the designed triazole and triazoline glycosides interacted strongly inside the active site of the enzyme (PDB ID: 2Q85). and exhibits high docking scores, higher than the standard drug. The range of docking scores is -7.99 kcal/mol compound (a) to -7.42 kcal/mol compound (e).

Equilibria of complexes in the aqueous cobalt(II)-N-(2-hydroxybenzyl)phenylalanine system and their biological activity compared to analogous Schiff base structures

Due to their excellent prospects in biological applications, Schiff bases and their complexes are a source of continuing interest. The present study examines the formation of four cobalt(II) complexes with the reduced Schiff base N-(2-hydroxybenzyl)phenylalanine (PhAlaSal) in alkaline aqueous solution by pH-metry. UV-Vis and ESI-MS studies confirmed the model of proposed species. Kinetic analysis indicated that the single- and bi-ligand cobalt(II) complexes transitioned from octahedral to tetrahedral structures. The Schiff base and its complexes detected under physiological pH were tested for antimicrobial abilities and compared with analogous structures of the Schiff base derivative, N-(2-hydroxybenzyl)alanine (AlaSal). The ability of these structures to influence cell growth was tested on L929 mouse fibroblasts and on cervix and gastric adenocarcinoma cancer cell lines. N-(2-hydroxybenzyl)phenylalanine demonstrates greater antimicrobial efficacy than N-(2-hydroxybenzyl)alanine but also higher cytotoxicity; however, it is nonetheless effective against cancer cells. In turn, AlaSal demonstrates low cytotoxicity for fibroblasts and high cytotoxicity for gastric adenocarcinoma epithelial cells at bacteriostatic concentration for Helicobacter pylori and Candida strains. The presence of these microorganisms in the gastric milieu supports the development of gastritis and gastric cancer; AlaSal therapy may be simultaneously effective against both. Due to their cytotoxicity, Schiff base complexes are not suitable for use against fungal and bacterial infections, but may effectively prevent cancer cell growth.

Data availability

Data will be made available on request.