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Review
. 2021 Apr 14;22(8):4027.
doi: 10.3390/ijms22084027.

Epigallocatechin Gallate for Management of Heavy Metal-Induced Oxidative Stress: Mechanisms of Action, Efficacy, and Concerns

Iwona Zwolak  1
Affiliations
Review

Epigallocatechin Gallate for Management of Heavy Metal-Induced Oxidative Stress: Mechanisms of Action, Efficacy, and Concerns

Iwona Zwolak. Int J Mol Sci. .

Abstract

In this review, we highlight the effects of epigallocatechin gallate (EGCG) against toxicities induced by heavy metals (HMs). This most active green tea polyphenol was demonstrated to reduce HM toxicity in such cells and tissues as testis, liver, kidney, and neural cells. Several protective mechanisms that seem to play a pivotal role in EGCG-induced effects, including reactive oxygen species scavenging, HM chelation, activation of nuclear factor erythroid 2-related factor 2 (Nrf2), anti-inflammatory effects, and protection of mitochondria, are described. However, some studies, especially in vitro experiments, reported potentiation of harmful HM actions in the presence of EGCG. The adverse impact of EGCG on HM toxicity may be explained by such events as autooxidation of EGCG, EGCG-mediated iron (Fe3+) reduction, depletion of intracellular glutathione (GSH) levels, and disruption of mitochondrial functions. Furthermore, challenges hampering the potential EGCG application related to its low bioavailability and proper dosing are also discussed. Overall, in this review, we point out insights into mechanisms that might account for both the beneficial and adverse effects of EGCG in HM poisoning, which may have a bearing on the design of new therapeutics for HM intoxication therapy.

Keywords: EGCG; antioxidant; epigallocatechin gallate; heavy metals; oxidative stress; reactive oxygen species.

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Conflict of interest statement

The author declares no conflict of interest.

Figures

Figure 1
Figure 1
Epigallocatechin gallate (EGCG) structure. EGCG is composed of four rings designated as A, B, C, and D. The A and C rings form a benzopyran ring system, which is connected with the pyrogallol (the B ring) and gallate (the D ring) moiety at the C-2 and C-3 positions, respectively [45]. The role of the functional groups in the antioxidant properties of EGCG was described on the basis of other studies [49,50,51].
Figure 2
Figure 2
Major protective mechanisms observed in EGCG effects on HM toxicity in experimental studies. AP-1, activator protein 1; ARE, antioxidant response element; Keap1, Kelch-like ECH-associated protein 1; MDA, malondialdehyde; NF-κB, nuclear factor-kB; NO, nitric oxide; Nrf2, nuclear factor erythroid 2-related factor 2; 8′-oxodG, 8-oxo-2′-deoxyguanosine; ROS, reactive oxygen species; ↓, decreased.
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