Elsevier

Journal of Ethnopharmacology

Volume 210, 10 January 2018, Pages 296-310
Journal of Ethnopharmacology

Review
Molecular understanding of Epigallocatechin gallate (EGCG) in cardiovascular and metabolic diseases

https://doi.org/10.1016/j.jep.2017.08.035 Get rights and content

Abstract

Ethnopharmacological relevance

The compound epigallocatechin-3-gallate (EGCG), the major polyphenolic compound present in green tea [Camellia sinensis (Theaceae], has shown numerous cardiovascular health promoting activity through modulating various pathways. However, molecular understanding of the cardiovascular protective role of EGCG has not been reported.

Aim of the review

This review aims to compile the preclinical and clinical studies that had been done on EGCG to investigate its protective effect on cardiovascular and metabolic diseases in order to provide a systematic guidance for future research.

Materials and methods

Research papers related to EGCG were obtained from the major scientific databases, for example, Science direct, PubMed, NCBI, Springer and Google scholar, from 1995 to 2017.

Results

EGCG was found to exhibit a wide range of therapeutic properties including anti-atherosclerosis, anti-cardiac hypertrophy, anti-myocardial infarction, anti-diabetes, anti-inflammatory and antioxidant. These therapeutic effects are mainly associated with the inhibition of LDL cholesterol (anti-atherosclerosis), inhibition of NF-κB (anti-cardiac hypertrophy), inhibition of MPO activity (anti-myocardial infarction), reduction in plasma glucose and glycated haemoglobin level (anti-diabetes), reduction of inflammatory markers (anti-inflammatory) and the inhibition of ROS generation (antioxidant).

Conclusion

EGCG shows different biological activities and in this review, a compilation of how this bioactive molecule plays its role in treating cardiovascular and metabolic diseases was discussed.

Introduction

Cardiovascular disease (CVD), a kind of disease due to abnormal function of the heart as well as blood vessels, is known as the number one killer worldwide. It includes coronary heart disease, congenital heart disease, rheumatic heart disease, cerebrovascular disease and peripheral arterial disease. According to the 2013 Global Burden of Disease study, approximately 17.3 million deaths were caused by CVD, which represents 31.5% of all deaths. Among these, 7.4 million were having coronary heart disease and 6.7 million died due to stroke (European et al., 2016). Usually, a heart attack or stroke would be the first warning of underlying diseases. Both of them are acute events that are mainly caused by the presence of fatty deposits which block blood from flowing smoothly in the blood vessels and this event is known as atherosclerosis (Go et al., 2013; European et al., 2016). However, stroke can also be caused by the formation of blood clots. Framingham Heart Study found that the risk factors that lead to CVD through metabolic syndrome (diabetes and obesity) includes poor glucose tolerance, physical inactivity, tobacco use, hypertension, and high level of blood cholesterol (Go et al., 2013).

Numerous clinical approaches had been done to alleviate and cure CVD but none of were proven to show perfect results. Side effects including nausea and vomiting, dizziness, angina and edema are the typical symptoms when patients are given CVD medication therapies (Nagle et al., 2006). Transplantation of heart may be a hope for those patients who fail to recover from the conventional therapies, but there is a chance of organ rejection and the number of donors are limited. Hence, herbal medicine became another useful alternative therapy as they do not show any side effects. In addition, they are relatively cheaper than pharmaceutical drugs, easily acquired and can be used for multipurpose. One of the most valuable advantages of herbal medicine is that it helps in utilizing the body's natural healing process as it contains ingredients that are regularly produced by the body. Amongst numerous herbal medicines that have been discovered, green tea is found to be one of the therapeutic agents with most potential against CVD.

Green tea is the least processed tea from the buds of Camellia sinensis plant and it contains Epigallocatechin gallate (EGCG), which is an ester that forms from the reaction of epigallogatechin and gallic acid (Zaveri, 2006). EGCG can be found abundantly in green tea leaves (7.1 g per 100 g green tea leaves), oolong tea (3.4 g per 100 g oolong tea), and black tea leaves (1.1 g per 100 g black tea leaves) (Chacko et al., 2010). In Traditional Chinese Medicine and Ayurvedic practices, green tea has been used extensively as a stimulant, diuretic and astringent. Other traditional uses of green tea include promoting digestion, improving mental health and regulating blood sugar as well as body temperature (Cooper et al., 2005). Furthermore, due to the presence of catechin in EGCG, scientists believe that it may act as an antioxidant which plays a role in reducing the amount of free radicals involved in numerous diseases states including CVD (Lobo et al., 2010). This makes scientists believe that EGCG could be a potential therapeutic agent against CVD, which are mainly caused by oxidative stress. However, a review to understand the cardiovascular protective role of EGCG from molecular aspect has not been reported. This review aims to compile the information from preclinical (invivo and invitro) and clinical studies that had been done by collecting research journals published from the past 12 years (1995–2017) on this bioactive molecule.

Section snippets

Method

The information on EGCG (Fig. 1) relating to cardiac and metabolic diseases were collected from several databases such as Science direct, PubMed, NCBI, Springer and Google scholar, limiting publications from 1995 to 2017. We have searched the work related to EGCG and cardiovascular disease in PubMed.gov today results in a listing of 283 with the earliest publication dated 1997. From these publications, we have narrowed down search criteria by limiting to the below mentioned categories presented

Conclusion

As discussed in this review, EGCG has been showed to exert its beneficial effects on human especially on treating CVDs including atherosclerosis, cardiac hypertrophy and MI. It also exhibit anti-diabetic, anti-inflammatory, antioxidant, and antiapoptotic activities through modulating various signalling pathway demonstrated in Fig. 2. The major pathway that EGCG to treat CVD and DM is through the reduction of NF-kB expression and its downstream marker molecules.

This review attempts to enhance

Future directions

This review summarized the preclinical and clinical studies as solid evidences to prove that EGCG as a potential therapeutic agent to mitigate CVD diseases through different pathways. However, the inconsistent results within preclinical and clinical studies of EGCG is a key factor for future research and modification in bioavailability, potential side effects as well as dose frequency for human should be investigated carefully as they are important parameters to be addressed in order for this

Acknowledgements

This work was supported by BSc. (Hons) Pharmaceutical chemistry programme, School of Pharmacy, International medical university, Malaysia.

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