Synthesis, characterization, in-vitro anti-inflammatory and antimicrobial screening of metal(II) mixed diclofenac and acetaminophen complexes

Mixed ligand complexes derived from diclofenac potassium salt (Kdc) and acetaminophen (ace) has been synthesized and proposed to have a general formula [MB] where M = Co2+, Ni2+, Cu2+ and Zn2+and B = (ace)(dc)(H2O)2 except for Mn2+ complex which exists as [Mn(ace)(dc)OH2]. The complexes were characterized by solubility, melting point, conductivity, elemental analyses, UV-Vis, FT-IR spectroscopy, X-ray powder diffraction (XRPD) study and magnetic susceptibility measurement. Electronic absorption spectra data are characteristic of octahedral structures for [MB]. The IR spectra revealed a bidentate coordination mode. In acetaminophen, the nitrogen and carbonyl-O atoms of the amide group were involved while the carboxylate oxygen atoms of potassium diclofenac were used; typical of a carboxylic acid derivative. The compounds were screened for in-vitro anti-inflammatory activity by inhibition of albumin denaturation assay and antimicrobial activity against bacteria strains: Bacillus subtilis, Bacillus anthrax, Escherichia coli, Salmonella typhi and a fungus Aspergillus niger. Some of the tested compounds showed moderate anti-inflammatory activity when compared to the standard drug diclofenac potassium salt. The in-vitro antimicrobial screening revealed an increased activity of the complexes against the bacteria isolates compared to the free ligands.                     KEY WORDS: Metal(II) ion, NSAIDs, Anti-inflammatory activity, Diclofenac potassium salt, XRPD, Antimicrobial activity   Bull. Chem. Soc. Ethiop. 2021, 35(1), 77-86. DOI: https://dx.doi.org/10.4314/bcse.v35i1.

Mn(II), Co(II), Ni(II), and Cu(II) complexes of amino acid derived Schiff base ligand: Synthesis, characterization and in-vitro antibacterial investigations

Four complexes of Mn(II), Co(II), Ni(II) and Cu(II) with Schiff base ligand (H3L) derived from 2-amino-3-methylbutanoic acid and acetylacetonate were synthesized. All complexes were characterized by elemental analysis, Fourier-transform infrared spectroscopy and electronic spectroscopy. The results confirmed the coordination of the ligand to metals in tridentate fashion via the hydroxyl oxygen, the azomethine nitrogen and the enolic acetylacetonate oxygen. Antimicrobial activities were established for all complexes, free ligand and ciprofloxacin for comparison. Both the ligand and its metal complexes were active against Gram-positive and negative bacterial strains. The Cu(II) complex, showed highest antibacterial activity among the complexes screened. Other complexes displayed considerable antibacterial activity. Octahedral geometry was proposed for the metal(II) complexes with the Schiff base.                     KEY WORDS: Schiff base, Amino acid, Metal Complexes, Antibacterial agents   Bull. Chem. Soc. Ethiop. 2021, 35(1), 97-106. DOI: https://dx.doi.org/10.4314/bcse.v35i1.

Toxicological assessment of synthesized and characterized transition metal(II) complexes of eflornithine hydrochloride hydrate on albino rats

Transition metal complexes of Cu(II), Co(II) and Ni(II) with eflornithine hydrochloride hydrate (EFN), an antitrypanosomiasis drug, as ligand have been synthesized and characterized by melting point, elemental analysis, Fourier transform infrared (FTIR), electronic spectra, magnetic susceptibility and electrospray ionization mass spectrometry (ESI-MS). The FTIR spectral data suggested the coordination modes of the ligand to be bidentate, coordinated to the metal ions through its carboxylate oxygen atom and an amino nitrogen atom. From the microanalytical data, the stoichiometry of the metal complexes is 1:2 (metal to ligand). The electronic absorption and magnetic susceptibility studies generally suggested octahedral geometry for the metal complexes. Toxicological evaluation of the ligand (EFN) and complexes were carried out using albino rats. Twenty-five albino rats that were used for the experiment were randomly divided into five groups and animals in group 1 served as a control. All the animals were sacrificed twenty-four hours after completion of their doses. The results revealed a high level of toxicity of EFN than the synthesized metal complexes.                     KEY WORDS: Eflornithine hydrochloride hydrate, Carboxylate moiety, Antitrypanosomiasis drug, Toxicological evaluation, Albino rats   Bull. Chem. Soc. Ethiop. 2020, 34(3), 489-500. DOI: https://dx.doi.org/10.4314/bcse.v34i3.

Synthesis, Structural Elucidation and Antimicrobial Activity of Metal (II) Polypyridyl Complexes of 2-Amino-4-(Methylthio) Butanoic Acid

The interaction of selected biometals with dinitrogen donor ligand, 1,10-phennathroline (phen) and amino acid, 2-amino-4-(methylthio)butanoic acid (methionine; met) resulted in isolation of three mononuclear complexes. The prepared complexes were characterized by diverse techniques including elemental and spectroscopic analysis. From the analytical and spectral data, octahedral geometry was proposed to the synthesized metal (II) complexes. Bonding of the metal ion through N- and O- donor atoms of the ligands is revealed by infrared studies. The compounds showed moderate solubility in distilled water and in some common organic solvents. In vivo evaluation of the antimicrobial activities of the metal complexes showed improved inhibitory activity against some micro-organisms as compared to the ligands, with Co(II) and Cu(II) complexes showing the highest activities against the fungi. Keywords: antimicrobial; mixed ligands; amino acid; polypyridy