Combating Essential Metal Toxicity: Key Information from Optical Spectroscopy

Abstract Chelation therapy is one of the most effective and widely accepted methods of treatment to reduce metal toxicity caused by an excess amount of essential metals. Essential minerals play an important role in maintaining healthy human physiology. However, the presence of an excess amount of such essential metals can cause cell injury, which finally leads to severe life-threatening diseases. Chelating complexes can efficiently capture the targeted metal and can easily be excreted from the body. Commonly utilized metal chelators have major side effects including long-term damage to some organs, which has pointed out the need of less harmful biocompatible chelating agents. In this work, we have investigated the iron chelating property of curcumin through various spectroscopic tools by synthesizing and characterizing the iron–curcumin (Fe–Cur) complex. We have also investigated whether the synthesized materials are able to retain their antioxidant activity after the chelation of a substantial amount of metal ion. Our study unravels the improved antioxidant activity of the synthesized chelate complex. We further demonstrate that the proposed complex generates no significant reactive oxygen species (ROS) under dark conditions, which makes it a promising candidate for chelation therapy of iron toxicity. Femtosecond-resolved fluorescence studies further provide insight into the mechanism of activity of the new complex where electron transfer from ligand to metal has been observed prominently. Thus, the Fe–Cur complex has a potential to act as a dual activity medicine for excretion of toxic metal ions via chelation and as a therapeutic agent of oxidative stress caused by the metal ion as well.