Synthesis, antioxidant activity and antibacterial study of EGCG complexes with iron(III) ions

Tea is infamous for its iron absorption, which leads to iron deficiency due to its high polyphenols content that easily chelates non-heme iron. Thus, studying the formation of (-)-Epigallocatechin gallate (EGCG) complexes with iron ions in vitro might give more insight into their properties. UV and IR spectrums were recorded to determine the structure of EGCG complexes with iron(III) ions. Job's method, formation constants, free energy, and DPPH scavenging capacity were calculated. Disk diffusion assay was used to evaluate the antibacterial activity of these complexes against four different bacteria. The results showed the formation of [Fe(EGCG)(H2O)], [Fe(EGCG)2], and [Fe2(EGCG)(H2O)2] complexes in pH=7.4 with formation constants (log K) of 4.39, 4.78 and 3.93, respectively. The complexes' DPPH results didn't show any significant difference. The antibacterial study showed a small inhibition of the tested bacteria compared to the standard disk. It is suggested that if EGCG-iron complexes form in the body after tea consumption, they will still have the main properties of EGCG as an antioxidant and an antibacterial agent. They also might be considered in medical supplements to provide or reduce iron metal in the body.