The inhibitory effect of the amino acid complexes of Zn(II) on the growth of Aspergillus flavus and aflatoxin B1 production

Abstract

The zinc(II) complexes with amino acids as the ligands, Zn(Gln)2 (1), [Zn(Arg)2(OAc)]OAc·3H2O (2), Zn(His)2 (3), Zn(Gly)2 (4), Zn(Met)2 (5), and Zn(Cys)2 (6) (Gln = glutamine, Arg = arginine, His = histidine, Gly = glycine, Met = methionine, and Cys = cysteine) have been synthesized in aqueous solutions and characterized by elemental analysis and spectroscopic methods. In addition, the solid-state structure of 1 and 2 has been determined by single-crystal X-ray crystallography. X-ray analysis revealed that the central Zn(II) atom is six- and five- coordinated in 1 and 2, respectively. Furthermore, the antifungal activity of the synthesized complexes was investigated against the Aspergillus flavus fungus. The aqueous solutions of the zinc(II) amino acid complexes at various concentrations were added to the potato dextrose agar (PDA) medium containing spores of Aspergillus flavus, and the mixtures were then incubated at 25–30 °C for 6 days. The aflatoxin B1 produced in vitro was measured using enzyme-linked immunosorbent assay (ELISA). The increasing concentration of these complexes decreased the growth of Aspergillus flavus and aflatoxin B1 production, consequently. Furthermore, the results showed that the synthesized Zn(II) amino acid complexes are more antifungal active than the zinc(II) ion.