Metal-Based Antibacterial and Antifungal Agents: Synthesis, Characterization, and In Vitro Biological Evaluation of Co(II), Cu(II), Ni(II), and Zn(II) Complexes With Amino Acid-Derived Compounds

A series of antibacterial and antifungal amino acid-derived compounds and their cobalt(II), copper(II), nickel(II), and zinc(II) metal complexes have been synthesized and characterized by their elemental analyses, molar conductances, magnetic moments, and IR, and electronic spectral measurements. Ligands (L(1))−(L(5)) were derived by condensation of β-diketones with glycine, phenylalanine, valine, and histidine and act as bidentate towards metal ions (cobalt, copper, nickel, and zinc) via the azomethine-N and deprotonated-O of the respective amino acid. The stoichiometric reaction between the metal(II) ion and synthesized ligands in molar ratio of M : L (1 : 1) resulted in the formation of the metal complexes of type [M(L)(H(2)O)(4)]Cl (where M = Co(II), Cu(II), and Zn(II)) and of M : L (1 : 2) of type [M(L)(2)(H(2)O)(2)] (where M = Co(II), Cu(II), Ni(II), and Zn(II)). The magnetic moment data suggested for the complexes to have an octahedral geometry around the central metal atom. The electronic spectral data also supported the same octahedral geometry of the complexes. Elemental analyses and NMR spectral data of the ligands and their metal(II) complexes agree with their proposed structures. The synthesized ligands, along with their metal(II) complexes, were screened for their in vitro antibacterial activity against four Gram-negative (Escherichia coli, Shigella flexeneri, Pseudomonas aeruginosa, and Salmonella typhi) and two Gram-positive (Bacillus subtilis and Staphylococcus aureus) bacterial strains and for in vitro antifungal activity against Trichophyton longifusus, Candida albicans, Aspergillus flavus, Microsporum canis, Fusarium solani, and Candida glaberata. The results of these studies show the metal(II) complexes to be more antibacterial/antifungal against one or more species as compared to the uncomplexed ligands. The brine shrimp bioassay was also carried out to study their in vitro cytotoxic properties. Five compounds, (3), (7), (10), (11), and (22), displayed potent cytotoxic activity as LD(50) = 8.974 × 10(−4), 7.022 × 10(−4), 8.839 × 10(−4), 7.133 × 10(−4), and 9.725 × 10(−4) M/mL, respectively, against Artemia salina

Metaloantibiotici: Sinteza, karakterizacija i antimikrobno djelovanje kompleksa fluorokinolona s bizmutom na Helicobacter pylori

Novel organometallic compounds have been prepared by complexing the fluoroquinolones, norfloxacin, ofloxacin, ciprofloxacin, sparfloxacin, lomefloxacin, pefloxacin and gatifloxacin, with bismuth. The complexes were characterized by UV, IR, atomic absorption spectroscopy, elemental analysis, differential scanning calorimetry, thermogravimetric analysis and mass spectrometry. Their antibacterial potential against Helicobacter pylori and other microorganisms was investigated. These compounds were found to possess strong activity against Helicobacter pylori at a minimum inhibitory concentration of 0.5 mg Ll. They also exhibited moderate activity against Escherichia coli, Staphylococcus aureus, Bacillus pumilus and Staphylococcus epidermidis. These bismuth-fluoroquinolone complexes have the potential to be developed as drugs against H. pylori related ailments.Komplesacijom fluorokinolona, norfloksacina, ofloksacina, ciprofloksacina, sparfloksacina, lomefloksacina, pefloksacina i gatifloksacina s bizmutom pripravljeni su novi organometalni spojevi. Dobiveni kompleksi karakterizirani su UV, IR i atomskom apsorpcijskom spektroskopijom, elementarnom analizom, diferencijalnom pretražnom kalorimetrijom, termogravimetrijskom analizom i spektrometrijom masa. Nadalje, ispitivan je njihov učinak na Helicobacter pylori i druge mikroorganizme. Ispitivani spojevi pokazuju snažno djelovanje na Helicobacter pylori u koncentraciji 0,5 mg Ll te umjereno djelovanje na Escherichia coli, Staphylococcus aureus, Bacillus pumilus i Staphylococcus epidermidis. Kompleksi fluorokinolona s bizmutom potencijalni su lijekovi za infekcije uzrokovane H. pylori