Synthesis, spectroscopy and antimicrobial activity of iron complexes of some smoke flavour compounds

Iron (III) complexes of some smoke flavour compounds (2-allyloxyphenol, guaiacol, eugenol and 2-ethoxyphenol) were synthesised and characterised by UV-Vis spectroscopy and ESI mass spectrometry. The ligand metal binding ratio was found to be 1:1 by the Job plot method. Antimicrobial activity of the ligand iron complex was determined against Bacillus subtilis, Escherichia coli, Staphylococcus aureus and Pseudomonas aeruginosa. This activity was compared with that of the free ligand (four smoke flavour compounds). While enhanced antimicrobial activities of guaiacol and 2-ethoxyphenol iron complexes were observed, this effect was, however, limited for eugenol and 2-allyloxyphenol iron complexes. In this study, it was established for the first time that not only do smoke flavour compounds complex with iron which could potentially retard food spoilage, but also after complexation, some complexes attain antimicrobial activities compared to the inactive free ligands.