Epigallocatechin gallate: Phytochemistry, bioavailability, utilization challenges, and strategies

• Published in: Journal of food biochemistry Vol. 46; no. 8; pp. e14189 - n/a
• Main Authors: Mehmood, Shomaila, Maqsood, Maria, Mahtab, Nazia, Khan, Muhammad Issa, Sahar, Amna, Zaib, Sania, Gul, Shehla
• Format: Journal Article
• Language: English
• Published: United States 01-08-2022
• Subjects: bioactivity; bio‐accessibility; EGCG; glycosylation; nano‐chemoprevention; prodrugs; glycosylation; bioactivity; prodrugs; nano-chemoprevention; EGCG; bio-accessibility
• ISSN: 0145-8884; 1745-4514
• DOI: 10.1111/jfbc.14189

Epigallocatechin gallate (EGCG), a green tea catechin, has gained the attention of current study due to its excellent health‐promoting effects. It possesses anti‐obesity, antimicrobial, anticancer, anti‐inflammatory activities, and is under extensive investigation in functional foods for improvement. It is susceptible to lower stability, lesser bioavailability, and lower absorption rate due to various environmental, processing, formulations, and gastrointestinal conditions of the human body. Therefore, it is the foremost concern for the researchers to enhance its bioactivity and make it the most suitable therapeutic compound for its clinical applications. In the current review, factors affecting the bioavailability of EGCG and the possible strategies to overcome these issues are reviewed and discussed. This review summarizes structural modifications and delivery through nanoparticle‐based approaches including nano‐emulsions, encapsulations, and silica‐based nanoparticles for effective use of EGCG in functional foods. Moreover, recent advances to enhance EGCG therapeutic efficacy by specifically targeting its molecules to increase its bioavailability and stability are also described.
Practical applications
The main green tea constituent EGCG possesses several health‐promoting effects making EGCG a potential therapeutic compound to cure ailments. However, its low stability and bioavailability render its uses in many disorders. Synthesizing EGCG prodrugs by structural modifications helps against its low bioavailability and stability by overcoming premature degradation and lower absorption rate. This review paper summarizes various strategies that benefit EGCG under different physiological conditions. The esterification, nanoparticle approaches, silica‐based EGCG‐NPs, and EGCG formulations serve as ideal EGCG modification strategies to deliver superior concentrations with lesser toxicity for its efficient penetration and absorption across cells both in vitro and in vivo. As a result of EGCG modifications, its bioactivities would be highly improved at lower doses. The protected or modified EGCG molecule would have enhanced potential effects and stability that would contribute to the clinical applications and expand its use in various food and cosmetic industries.
EGCG is a bioactive compound present in green tea. EGCG contains pyrogallol as B‐rings while it contains an additional gallate moiety as a D‐ring, which increases the number of hydroxyl groups. The EGCG, due to galloyl moieties increasing in their hydroxyl groups, possesses more excellent antioxidant activities than EC and EGC. Considerable challenges in EGCG utilization are the low systemic bioavailability, less stability in alkaline media, temperature, high oxidative degradation, metabolic transformations, as well as toxicity at higher concentrations. Hence, some effective strategies are introduced to overcome its lower bioavailability and stability issues.