iron (Fe)-(-)-epigallocatechin gallate (EGCG)

Overview

Iron (Fe)-(-)-epigallocatechin gallate (EGCG) refers to a metal–polyphenol coordination material formed from iron ions and (-)-epigallocatechin gallate (EGCG), a major catechin from green tea. In biomedical research, Fe–EGCG systems are typically discussed as metal polyphenolic networks (MPNs) or related coordination assemblies rather than as a single small-molecule drug. These materials are of interest because EGCG contains multiple phenolic groups capable of binding metal ions and interacting with proteins, polymers, and nanoparticle surfaces.

Biologically, EGCG is widely studied for antioxidant, anti-inflammatory, antimicrobial, and anticancer-associated activities, but its practical use is often limited by low bioavailability and instability. Complexation with iron can alter EGCG’s physicochemical behavior, including its assembly into nanostructures, surface coating properties, and responsiveness in biological environments. In recent studies, Fe–EGCG has been used as a functional coating or network component in tumor imaging and therapy platforms, especially in combination with copper sulfide nanoparticles and other nanomedicine components.

Focus of Latest Publications

Recent studies have used iron (Fe)-EGCG primarily as a functional metal-phenolic network for nanomedicine. In one study, copper sulfide nanoparticles were coated with Fe–EGCG metal polyphenolic networks to create a targeted platform for MR imaging-directed chemo/photothermal/chemodynamic synergetic therapy of tumors. This work positions Fe–EGCG as a surface engineering layer that supports multimodal cancer treatment, combining imaging with therapeutic functions. The reported application is consistent with the broader use of EGCG-based coordination assemblies in tumor-targeting nanodrugs, including systems built from EGCG with gadolinium, folic acid, polyethylene glycol (PEG), polyethylenimine (PEI·NH2), and other components.

Although several of the provided publications focus on EGCG rather than iron–EGCG specifically, they help define the biomedical context of this entity. EGCG was repeatedly described as a major catechin from green tea with antioxidant and anticancer activity, but with limited clinical translation because of instability and low bioavailability. To address these limitations, researchers developed self-assembled nanoparticles, hydrogel beads, and protein–polysaccharide complexes. Examples include EGCG-loaded alginate-peanut protein hydrogel beads, sodium caseinate–gum arabic–EGCG ternary complexes, and EGCG–tannic acid nanoparticles against triple-negative breast cancer. These studies emphasize that EGCG can be incorporated into delivery systems that improve stability, digestive behavior, targeting, or cellular uptake.

The recent literature also shows EGCG being used as a cross-linking or responsive component in biomaterials. In antibacterial and wound-healing systems, EGCG was incorporated into chitosan-based hydrogels and Ag@EGCG composites, including a multifunctional hydrogel for MRSA-infected wounds and a dual-responsive hydrogel for diabetic wound healing. In these settings, EGCG contributed antioxidant and immunomodulatory functions, while phenylboronic acid and ROS-responsive linkages enabled environmental responsiveness. Related work on EGCG–protein interactions showed that EGCG can cross-link plant proteins and that oxidized quinone-modified EGCG (QEGCG) may interact differently with proteins, affecting foaming, emulsifying, and hypoglycemic properties.

In cancer-focused studies, EGCG was investigated as an anti-metastatic and anti-cancer agent. One publication reported that EGCG attenuated arecoline-induced migration and invasion in esophageal squamous cell carcinoma cells, with effects associated with EGFR/AKT/P38 signaling. Another study described EGCG-based self-assembled nanoparticles with tannic acid that mediated mitochondrial damage in triple-negative breast cancer. These findings reinforce the role of EGCG as a biologically active scaffold for therapeutic nanomaterials, and Fe–EGCG fits into this same design logic by enabling metal coordination, structural assembly, and imaging functionality.

Additional studies expanded EGCG chemistry into enzyme engineering and glycosylation. A loop-exchanged sucrose phosphorylase variant from Streptococcus mutans was engineered for regioselective 4″-O-glucosylation of EGCG, reflecting efforts to improve EGCG stability and utility through derivatization. Other work used EGCG in ternary complexes with sodium caseinate and gum arabic, or in hydrogel beads with sodium alginate, peanut protein isolate, pectin-based crosslinking, and chitosan-based coating strategies. Collectively, these studies show that EGCG is a versatile bioactive polyphenol whose coordination with iron is part of a broader strategy to convert a chemically fragile natural product into a functional biomedical material.