ABSTRACT
        Background and objectives: Synthesis and characterization of several metal complexes (metal ions: Co2+, Ti4+ and Ce3+) of macroacyclic Schiff base ligand have been reported. The Schiff base ligand is prepared from the condensation reaction of 1, 4-di-(4-fluoro-2-aminophenoxy) butane with salicylaldehyde in ethanol. In addition, antibacterial activity of metal ions, Schiff base ligand and their complexes have been investigated. Recent studies show that many Schiff base complexes have antibacterial activity against Gram-positive and Gram-negative bacteria. Therefore, we aimed to synthesize new Schiff base complexes and evaluate their antibacterial activity against a number of Gram-positive and Gram-negative bacteria.
         Methods: Schiff base ligand and their complexes were characterized by mass spectrometry and IR, H-NMR and C-NMR spectroscopy. The in vitro antibacterial activity of the Schiff base ligand, metal ions and their complexes were evaluated against some Gram-positive and Gram-negative bacteria by disk diffusion method and determining minimum inhibitory concentration.
          Results: In this study, the Schiff base complexes had good antibacterial activity, but the Schiff base ligand and metal ions did not show any antibacterial effect. In some cases, the antibacterial effect of the complexes was higher than that of the standard antibiotics tetracycline and gentamycin. The titanium complex showed the highest antibacterial activity in both methods. This complex created the largest growth inhibition zone (diameter: 100mm) against Staphylococcus aureus, and had the lowest minimum inhibitory concentration against Bacillus subtilis (6.75 mg/ml).
          Conclusion: The compounds synthesized in our study have strong antibacterial activity.
          Keywords: Schiff base complex, Schiff base ligand, antibacterial activity, Staphylococcus aureus, Bacillus subtilis.

Background: Due to the growing problem of antibiotic-resistant bacteria and rising consumer preference for natural food preservatives, there is an increased interest in plant-based antimicrobial agents. While Salix aegyptiaca (S. aegyptiaca), also known as Musk Willow, is a promising source of bioactive compounds, its antibacterial properties have not been extensively studied. Therefore, this research investigates the chemical composition and antibacterial effectiveness of essential oils extracted from the leaves and male inflorescences of S. aegyptiaca against important foodborne pathogens like Staphylococcus aureus (S. aureus), Escherichia coli (E. coli), Listeria monocytogenes (L. monocytogenes), and Salmonella enteritidis (S. enteritidis).
Methods: Essential oils were extracted from the leaves and male inflorescences of S. aegyptiaca through hydrodistillation. The chemical composition of these oils was then determined by gas chromatography-mass spectrometry (GC-MS) to identify their bioactive constituents. The antibacterial efficacy of the extracted oils was assessed using several methods, including the determination of the minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC), as well as diffusion assays (Agar disk and agar well diffusion).
Results: GC-MS analysis revealed that the leaf oil was predominantly composed of 1,4-dimethoxybenzene, citronellol, and eugenol, whereas carvone was the main constituent of the male inflorescence oil. The leaf oil demonstrated superior antimicrobial activity, particularly against S. aureus, for which the MIC was determined to be 1250 µg/mL. Both oils indicated limited efficacy against Gram-negative bacteria. Of the strains tested, S. aureus proved to be the most susceptible, while E. coli exhibited the highest resistance.
Conclusion: The essential oils extracted from S. aegyptiaca, especially from its leaves, have shown significant antibacterial effects against common foodborne pathogens. This suggests they could be used as natural food preservatives, offering a viable alternative to synthetic additives. Additional research is necessary to investigate their use in food products and to establish their toxicological safety.