Synthesis, structural characterization, and biological studies of ATBS–M complexes (M(II) = Cu, Co, Ni, and Mn): Access for promising antibiotics and anticancer agents

Abstract

A new bidentate Schiff base ligand (ATBS [4‐bromo‐2‐(thiazole‐2‐yliminomethyl)phenol]) was synthesized via the condensation reaction of 2‐aminothiazole with 5‐bromosalicylaldehyde in ethanol. The reaction of ATBS with transition metal salts of Cu(II), Co(II), Ni(II), and Mn(II) afforded the corresponding ATBS–M complexes. Results from physicochemical and spectral analyses, such as elemental analysis, infrared, UV–Vis spectroscopy, magnetic susceptibility, and molar conductance, revealed a nonelectrolytic nature with octahedral (Oh) geometry and a metal/ligand ratio of 1:2 for Cu(II), Co(II), and Ni(II), but 1:1 for the Mn(II) complex. The density functional theory (DFT) calculations are correlated very well with the proposed structure and molecular geometry of the complexes as [M(ATBS)2] (M = Cu, Co, and Ni) and [Mn(ATBS)(H2O)2]. Significantly, the prepared compounds showed strong inhibition activity for a wide spectrum of bacteria (Escherichia coli, Bacillus subtilis, and Staphylococcus aureus) and fungi (Candida albicans, Aspergillus flavus, and Trichophyton rubrum), with the ATBS–Ni complex being the most promising antibiotic agent. Molecular docking studies of the binding interaction between the title complexes with the bacterial protein receptor CYP51 revealed clear insights about the inhibition nature against the studied microorganisms, with the following order: ATBS–Cu > ATBS–Mn > ATBS–Ni > ATBS–Co for complex stability. Moreover, the cytotoxicity measurements of all prepared metal complexes against the colon carcinoma (HCT‐116) and hepatocellular carcinoma (Hep‐G2) cell lines showed exceptional anticancer efficacy of the complexes as compared with the free ATBS Schiff base ligand. Significantly, the results attested that ATBS–Cu is the most effective complex against HCT‐116 cells, whereas ATBS–Mn has the highest cytotoxic efficiency against Hep‐G2 cells. Furthermore, electronic spectra, viscosity measurements, and gel electrophoresis techniques were employed to probe the interaction of all prepared ATBS–metal complexes with calf thymus (CT)‐DNA. Results confirmed that all complexes are strongly bound to CT‐DNA via intercalation mode, with the ATBS–Co complex having the highest binding ability.

Enhanced In Vivo Wound Healing Efficacy of a Novel Hydrogel Loaded with Copper (II) Schiff Base Quinoline Complex (CuSQ) Solid Lipid Nanoparticles

“…It was noted that, the wound healing effect of copper (II) mixed ligand complex of Salen Schiff base ligand and 8-hydroxy quinoline is not much explored. By considering the above facts and in continuation of our previous investigations [9,15,16]; herein we report the synthesis, spectral characterization, in vitro antimicrobial, and in vivo wound healing evaluation of the Cu (II) mononuclear complex of an ONNO donor Schiff base ligand and 8-hydroxy quinoline.…”

Synthesis, characterization and anticancer activity of Ni(II), Cu(II), Pd(II) and Au(III) complexes derived from novel Mannich base

“…Melting point was determined by the open capillary method using a hot stage Gallenkamp melting point apparatus and was uncorrected. 1 H-NMR and 13 C-NMR spectra were recorded on a Bruker spectrophotometer model AV 400 Advance-III for 400 MHz in DMSO-d6 solution with the TMS as an internal standard. Infra-red spectra were recorded with a FT-IR.8400s Shimadzu spectrophotometer at range (4000-200) cm −1 using CsI disks.…”

“…The 1 H-NMR and 13 C-nuclear spectra of the ligand (L) showed variable signals due to several characteristic groups. Hence, in the spectra of C 1 -C 4 complexes, CH 3 group signal suffered shifting due to the coordination of acetone carbonyl C═O with the metal ions.…”

“…9 Imine compounds have been known since 1864 when Hugo Schiff was the first researcher who synthesized carbon nitrogen double bond (C═N). 10 Schiff bases are considered as a very important class of organic compounds, having wide applications in many biological aspects, [11][12][13][14][15] it's important as an intermediate in preparing α-aminonitrile compounds. α-aminonitrile compounds contain the functional groups amine and nitrile on the same carbon atom.…”

Three metal complexes with a pyridyl Schiff base: cytotoxicity, migration and mechanism of apoptosis

“…3,4 In recent years, transition metal complexes have been intensively researched as novel antitumor and antibacterial agents, 5 and a series of transition metal complexes were synthesized by substituting ligands and modifying known chemical structures, especially copper complexes, which are considered as alternatives to platinum-based chemotherapeu-tic agents due to their low toxicity and unique biocompatibility and pharmacological effects. [5][6][7] Other transition metal complexes have also been synthesized and investigated with significant biological activity. [8][9][10] The biological activity of cadmium complexes has not been further investigated as it is well known that Cd has great toxicity to the human body and metabolizes slowly in the human body.…”