Prooxidant Effects of Epigallocatechin-3-Gallate in Health Benefits and Potential Adverse Effect

Abstract

Epigallocatechin-3-gallate (EGCG) is the major polyphenolic compound present in green tea and is generally regarded as an effective antioxidant. However, its chemical reactivity makes it susceptible to generate reactive oxygen species (ROS) via autooxidation and exhibit prooxidant effects. The prooxidant actions of EGCG could play a dual role, being both beneficial and harmful. This review summarized recent research progress on (1) the anticancer, antiobesity, and antibacterial effects of EGCG and (2) the possible toxicity of EGCG. The major focus is on the involvement of prooxidant effects of EGCG and their effective doses used. Considering dosage is a crucial factor in the prooxidant effects of EGCG; further studies are required to find the appropriate dose at which EGCG could bring more health benefits with lower toxicity.

Evaluation of the anti-oxidative and ROS scavenging properties of biomaterials coated with epigallocatechin gallate for tissue engineering

“…Consistently, the Mg-E surface exhibited 2-3-fold greater Fe conversion/ABTS scavenging activity than Na-E surface, suggesting that phenolic contents on the surface appear to be responsible for antioxidant activity to reduce Fe (Fe 3 + → Fe 2 + ) and to scavenge radicals [31] . It has been reported that the hydroxyl groups in phenolic ring structure of EGCG can scavenge radicals and chelate metal ion during self-oxidation, and the electron transfer in phenolic πelectrons is dependent on the amount of EGCG coated on the surface of the substrate [32] .…”

Novel Delivery Systems of Polyphenols and Their Potential Health Benefits

“…However, the anticancer capacity of EGCG depends on the dose, requiring a significant amount of this compound to observe its antitumor effects; this is a challenge because, in everyday life, the amount of green tea consumed by individuals is low, and the bioavailability of this compound is also weak [146]. We must also emphasize that high doses of EGCG can cause cytotoxicity in vitro, whereas, in vivo, individuals may suffer from hepatotoxicity, nephrotoxicity, and gastrointestinal disorders (vomiting and diarrhea) [147]. Although EGCG has a high activity, it cannot be easily used in the drug industry or as a natural additive due to its oxidability and instability, which compromise its bioavailability.…”

“…Regardless of the mode of administration of this compound in a biological system, its bioavailability will be low [148]. Most of the ingested EGCG is absorbed in the small intestine and then degraded by microorganisms in the large intestine, leaving only 0.2-2% of the initial amount in the body [147]. As a result, it is critical to comprehend EGCG's possible toxicity, dosages, and use.…”

EGCG, a Green Tea Catechin, as a Potential Therapeutic Agent for Symptomatic and Asymptomatic SARS-CoV-2 Infection

“…Since SARS-CoV-2 PLPro R166 mutation completely abrogated its deubiquitinase and deISGylation activity, binding of catechins to R166 is predicted to be inhibitory for its biological function. Although there are emerging reports of cellular toxicity of high doses of EGCG in vitro and in the human body [ 83 , 84 , 85 ], the very low oral bioavailability of EGCG [ 83 , 86 , 87 ] nevertheless makes it an effective therapeutic agent when the appropriate dosage is determined. Not only have we addressed SARS-CoV-2 PLPro as a specific target of catechins, but we have also provided ample literature-based findings of EGCG targeting the proinflammatory IL-1β and IL-6 signaling pathways in this review.…”