Absorption, metabolism, anti-cancer effect and molecular targets of epigallocatechin gallate (EGCG): An updated review

Abstract

Green tea is one of the most popular beverages in the world, especially in Asian countries. Consumption of green tea has been demonstrated to possess many health benefits, which mainly attributed to the main bioactive compound epigallocatechin gallate (EGCG), a flavone-3-ol polyphenol, in green tea. EGCG is mainly absorbed in the intestine, and gut microbiota play a critical role in its metabolism prior to absorption. EGCG exhibits versatile bioactivities, with its anti-cancer effect most attracting due to the cancer preventive effect of green tea consumption, and a great number of studies intensively investigated its anti-cancer effect. In this review, we therefore, first stated the absorption and metabolism process of EGCG, and then summarized its anti-cancer effect in vitro and in vivo, including its manifold anti-cancer actions and mechanisms, especially its anti-cancer stem cell effect, and next highlighted its various molecular targets involved in cancer inhibition. Finally, the anti-cancer effect of EGCG analogs and nanoparticles, as well as the potential cancer promoting effect of EGCG were also discussed. Understanding of the absorption, metabolism, anti-cancer effect and molecular targets of EGCG can be of importance to better utilize it as a chemopreventive and chemotherapeutic agent.

Rethinking the Mechanism of the Health Benefits of Proanthocyanidins: Absorption, Metabolism, and Interaction with Gut Microbiota

“…studied the absorption rate of four different kinds of monomeric proanthocyanidins in human subjects and found that the resulting plasma levels at 2 and 4 hr after consumption were ranked as follows: (−)‐EC > (+)­C = (+)­EC > (−)­C, and found 3’‐ O ‐methylated and 4’‐ O‐ methylated metabolites (Ottaviani et al., ). Similar results could also be found in other monomeric proanthocyanidins, such as EGCG (Gan, Li, Sui, & Corke, ; Takagaki & Nanjo, ). However, epi‐isomers might not always be easier to be absorbed compared with non‐epi‐isomers.…”

“…showed that 9.55 µmol (–)‐EC and the derivatives were recovered in human urine during 48 hr after they ingested 387.58 µmol of (–)‐EC measured by UHPLC‐ESI‐MS/MS without deconjugating enzymes (Castello et al., ). Another monomeric proanthocyanidins, EGCG with an extra group of gallic acid and larger Mw, showed an absorption rate of 0.012% in fasted rats and 0.32% in human plasma in 1 hr without using deconjugating enzymes in the study (Gan et al., ; Kale et al., ). A recent systematic review by Hu et al.…”

Targeting cancer stem cells with dietary phytochemical - Repositioned drug combinations

“…Chen components, including EGCG, inhibited normal rat neurosphere adhesion and migration [61]. EGCG has pleiotropic activity on multiple cellular targets, both genetic and epigenetic (including DNA methyltransferase, NFκB, AMPK signaling pathway) [62][63][64]. It can act on its target with very impressive sensitivity, KD of 39.9 nM for the 67 Kd laminin receptor [65].…”

Dietary Intervention by Phytochemicals and Their Role in Modulating Coding and Non-Coding Genes in Cancer

“…EGCG is represented by the most bioactive flavone-3-ol phenolic compound, this can be attributed to their eight free hydroxyl groups, responsible for the high versatile biological role [32]. The substitution with a methoxyl leads to a reduced antioxidant effect in the case of anthocyanidins compounds.…”