Epicatechin-3-Gallate

Epicatechin-3-Gallate at a Glance

Epicatechin-3-gallate, almost always abbreviated ECG, is a galloylated flavan-3-ol — the molecule (−)-epicatechin carrying an extra gallic acid unit esterified onto its C-3 position. It is one of the four principal catechins of green tea (Camellia sinensis), alongside EGCG (epigallocatechin-3-gallate), EGC (epigallocatechin) and EC (epicatechin), and it sits chemically between the other two: like EC it has a catechol B-ring, but like EGCG it carries the galloyl ester ^{10,12Reference 10Braicu C et al. · 2011The relationships between biological activities and structure of flavan-3-olsView study →Reference 12Moore RJ et al. · 2009Green tea (Camellia sinensis) catechins and vascular functionView study →}.

That single galloyl group is the whole story of ECG. It makes the molecule a stronger antioxidant and protein-binder than non-gallated catechin or epicatechin — but also a more poorly absorbed one, because the bulky, hydrophilic ester is a substrate for efflux and gut-microbial hydrolysis ^{11,12Reference 11Lee MJ et al. · 2002ObservationalPharmacokinetics of tea catechins after ingestion of green tea and (−)-epigallocatechin-3-gallate by humans: formation of different metabolites and individual variabilityView study →Reference 12Moore RJ et al. · 2009Green tea (Camellia sinensis) catechins and vascular functionView study →}. Most of what ECG “does” has been shown for the isolated molecule in vitro.

Its most distinctive isolate signal is antibacterial: ECG re-sensitises methicillin-resistant Staphylococcus aureus (MRSA) to β-lactam antibiotics by inserting into the bacterial membrane ^{1,2,3Reference 1Stapleton PD et al. · 2004Modulation of beta-lactam resistance in Staphylococcus aureus by catechins and gallatesView study →Reference 2Stapleton PD et al. · 2007The beta-lactam-resistance modifier (−)-epicatechin gallate alters the architecture of the cell wall of Staphylococcus aureusView study →Reference 3Bernal P et al. · 2010Insertion of epicatechin gallate into the cytoplasmic membrane of methicillin-resistant Staphylococcus aureus disrupts penicillin-binding protein (PBP) 2a-mediated beta-lactam resistance by delocalizing PBP2View study →}. As with the whole green-tea story, the honest framing matters — the human cardiovascular and metabolic data belong to whole catechin mixtures and green-tea extracts, in which ECG is one contributor among several, and the headline extract claims (and the high-dose hepatotoxicity signal) track EGCG, not ECG specifically ^{12Reference 12Moore RJ et al. · 2009Green tea (Camellia sinensis) catechins and vascular functionView study →}.

A Gallated Green-Tea Catechin

The defining feature of ECG is the C-3 galloyl ester — a molecule of gallic acid bonded to the flavan-3-ol core. Reading the four main green-tea catechins side by side makes the point:

Catechin	B-ring	C-3 galloyl ester?
Epicatechin (EC)	catechol (3′,4′-diOH)	no
Epigallocatechin (EGC)	pyrogallol (3′,4′,5′-triOH)	no
Epicatechin-3-gallate (ECG)	catechol (3′,4′-diOH)	yes
Epigallocatechin-3-gallate (EGCG)	pyrogallol (3′,4′,5′-triOH)	yes

ECG differs from EC only by the added galloyl group, and from EGCG only by lacking the extra 5′-hydroxyl on the B-ring (catechol vs pyrogallol) ^{10Reference 10Braicu C et al. · 2011The relationships between biological activities and structure of flavan-3-olsView study →}. That places it as the gallated catechol catechin, one structural step away from each of its more-famous siblings.

The galloyl group is a trade-off. On the one hand it markedly increases activity: across radical-scavenging, membrane, enzyme-inhibition and antiproliferative assays, the gallated catechins (ECG, EGCG) consistently outperform their non-gallated homologues (EC, EGC), because the galloyl ring adds hydroxyls and a second phenolic system for radical scavenging and protein binding ^{5,6,10Reference 5Terao J et al. · 1994Protective effect of epicatechin, epicatechin gallate, and quercetin on lipid peroxidation in phospholipid bilayersView study →Reference 6Caturla N et al. · 2003The relationship between the antioxidant and the antibacterial properties of galloylated catechins and the structure of phospholipid model membranesView study →Reference 10Braicu C et al. · 2011The relationships between biological activities and structure of flavan-3-olsView study →}. On the other hand it lowers absorption — the galloylated catechins are the least bioavailable of the four, being larger, more subject to efflux transport, and hydrolysed by gut bacteria back toward gallic acid and epicatechin ^{11,12Reference 11Lee MJ et al. · 2002ObservationalPharmacokinetics of tea catechins after ingestion of green tea and (−)-epigallocatechin-3-gallate by humans: formation of different metabolites and individual variabilityView study →Reference 12Moore RJ et al. · 2009Green tea (Camellia sinensis) catechins and vascular functionView study →}. This is the recurring tension on the page: ECG is more potent in the tube and less available in the body than plain epicatechin.

What It's Used For

ECG’s pharmacology is almost entirely preclinical and mostly on the isolated molecule. The one place it has a genuinely distinctive signal — separate from “generic catechin antioxidant” — is as a β-lactam-resistance modifier in staphylococci. Everywhere else it is best read as a potent-in-vitro member of the catechin family whose human relevance runs through whole green tea.

Evidence by IndicationStrength of support · Beta

Support is an experimental score — weighted by study type (human > animal > in vitro) and volume. A beta, not a validated metric. Every row here is preclinical (in vitro / ex vivo), so scores stay modest by design; the antibacterial row ranks highest for having a defined, ECG-specific mechanism replicated across several studies. Each application links to its write-up.

01β-Lactam-resistance modifier (MRSA)Shaky44%Multiple mechanistic studies + a zebrafish-embryo infection model; isolate ^{1,2,3,4Reference 1Stapleton PD et al. · 2004Modulation of beta-lactam resistance in Staphylococcus aureus by catechins and gallatesView study →Reference 2Stapleton PD et al. · 2007The beta-lactam-resistance modifier (−)-epicatechin gallate alters the architecture of the cell wall of Staphylococcus aureusView study →Reference 3Bernal P et al. · 2010Insertion of epicatechin gallate into the cytoplasmic membrane of methicillin-resistant Staphylococcus aureus disrupts penicillin-binding protein (PBP) 2a-mediated beta-lactam resistance by delocalizing PBP2View study →Reference 4Stapleton PD et al. · 2006Potentiation of catechin gallate-mediated sensitization of Staphylococcus aureus to oxacillin by nongalloylated catechinsView study →}

02Antioxidant (membrane lipid peroxidation)Shaky40%Ex-vivo/in-vitro; gallated > non-gallated potency ^{5,6,10Reference 5Terao J et al. · 1994Protective effect of epicatechin, epicatechin gallate, and quercetin on lipid peroxidation in phospholipid bilayersView study →Reference 6Caturla N et al. · 2003The relationship between the antioxidant and the antibacterial properties of galloylated catechins and the structure of phospholipid model membranesView study →Reference 10Braicu C et al. · 2011The relationships between biological activities and structure of flavan-3-olsView study →}

03Metabolic enzyme inhibitionShaky32%In-vitro xanthine oxidase, anti-glycation, AMPK cell model ^{7,8,9Reference 7Zhu M et al. · 2021Epicatechin gallate as xanthine oxidase inhibitor: inhibitory kinetics, binding characteristics, synergistic inhibition, and action mechanismView study →Reference 8Wu X et al. · 2019Inhibitory effect of epicatechin gallate on protein glycationView study →Reference 9Lin HH et al. · 2025In vitroAMPK-targeting effects of (−)-epicatechin gallate from Hibiscus sabdariffa Linne leaves on dual modulation of hepatic lipid accumulation and glycogen synthesis in an in vitro oleic acid modelView study →}

04Antiproliferative (galloylated catechin)Shaky26%In-vitro cancer-cell assays; class effect of the galloyl group ^{10Reference 10Braicu C et al. · 2011The relationships between biological activities and structure of flavan-3-olsView study →}

Mechanisms

The load-bearing point is the galloyl group: it is what lifts ECG above non-gallated epicatechin in nearly every assay, and simultaneously what tethers it to the membrane (the antibacterial mechanism) and to dietary proteins (astringency, iron binding).

Pharmacokinetics

ECG is one of the least bioavailable green-tea catechins. The galloyl ester makes it larger and more hydrophilic than epicatechin, and it is subject to efflux transport and gut-microbial hydrolysis — bacteria cleave the ester back toward gallic acid and epicatechin — so systemic levels are low ^{11,12Reference 11Lee MJ et al. · 2002ObservationalPharmacokinetics of tea catechins after ingestion of green tea and (−)-epigallocatechin-3-gallate by humans: formation of different metabolites and individual variabilityView study →Reference 12Moore RJ et al. · 2009Green tea (Camellia sinensis) catechins and vascular functionView study →}. Human catechin pharmacokinetic studies illustrate the family: after green-tea ingestion, plasma catechins peak at ~1.3–1.6 h, circulate largely as conjugates (glucuronides/sulfates) and methylated metabolites, and clear within a day, with large between-subject variability ^{11Reference 11Lee MJ et al. · 2002ObservationalPharmacokinetics of tea catechins after ingestion of green tea and (−)-epigallocatechin-3-gallate by humans: formation of different metabolites and individual variabilityView study →}. Notably, the most-cited human PK study measured EGCG, EGC and EC but not ECG, which is emblematic of the data gap for this specific molecule ^{11Reference 11Lee MJ et al. · 2002ObservationalPharmacokinetics of tea catechins after ingestion of green tea and (−)-epigallocatechin-3-gallate by humans: formation of different metabolites and individual variabilityView study →}. The galloylated catechins (ECG, EGCG) generally show slower, more persistent, lower-magnitude plasma appearance than the non-gallated ones. The practical consequence is the through-line: the concentrations at which ECG is active in vitro are well above what a cup of tea delivers to plasma.

Clinical Trials

There are no controlled clinical trials of isolated epicatechin-3-gallate. Human evidence exists only for green tea and green-tea catechin mixtures/extracts, in which ECG is one of several catechins and rarely the variable of interest ^{12Reference 12Moore RJ et al. · 2009Green tea (Camellia sinensis) catechins and vascular functionView study →}. Where a single catechin is credited, it is usually EGCG.

Last checked: July 2026.

Isolate vs. Plant Studies

ECG sits firmly on the isolate-mechanism / plant-efficacy split. The mechanistic work is almost all the isolated molecule: the Stapleton–Taylor MRSA series tests purified ECG (and its epimer catechin gallate) directly ^{1,2,3,4Reference 1Stapleton PD et al. · 2004Modulation of beta-lactam resistance in Staphylococcus aureus by catechins and gallatesView study →Reference 2Stapleton PD et al. · 2007The beta-lactam-resistance modifier (−)-epicatechin gallate alters the architecture of the cell wall of Staphylococcus aureusView study →Reference 3Bernal P et al. · 2010Insertion of epicatechin gallate into the cytoplasmic membrane of methicillin-resistant Staphylococcus aureus disrupts penicillin-binding protein (PBP) 2a-mediated beta-lactam resistance by delocalizing PBP2View study →Reference 4Stapleton PD et al. · 2006Potentiation of catechin gallate-mediated sensitization of Staphylococcus aureus to oxacillin by nongalloylated catechinsView study →}, as do the membrane-antioxidant ^{5,6Reference 5Terao J et al. · 1994Protective effect of epicatechin, epicatechin gallate, and quercetin on lipid peroxidation in phospholipid bilayersView study →Reference 6Caturla N et al. · 2003The relationship between the antioxidant and the antibacterial properties of galloylated catechins and the structure of phospholipid model membranesView study →}, xanthine-oxidase ^{7Reference 7Zhu M et al. · 2021Epicatechin gallate as xanthine oxidase inhibitor: inhibitory kinetics, binding characteristics, synergistic inhibition, and action mechanismView study →}, anti-glycation ^{8Reference 8Wu X et al. · 2019Inhibitory effect of epicatechin gallate on protein glycationView study →} and antiproliferative ^{10Reference 10Braicu C et al. · 2011The relationships between biological activities and structure of flavan-3-olsView study →} studies. As a mechanism base for the isolate, that is a genuine strength — ECG is not merely inferred from whole-tea effects.

The human evidence, by contrast, is entirely the plant/mixture. Green-tea catechin trials dose whole extracts or total catechins, within which ECG is one poorly-absorbed component travelling with EGCG, EGC, EC, caffeine and other polyphenols ^{12Reference 12Moore RJ et al. · 2009Green tea (Camellia sinensis) catechins and vascular functionView study →}. In the tea leaf ECG co-occurs with the other three catechins and, on oxidation during black-tea processing, is partly converted into dimeric theaflavins and polymeric thearubigins — so black and oolong teas carry less monomeric ECG than green tea ^{12Reference 12Moore RJ et al. · 2009Green tea (Camellia sinensis) catechins and vascular functionView study →}. No human outcome has been attributed to ECG specifically, and its low bioavailability means whole-tea effects should not be reassigned to it.

Prevalence in Nature

ECG is a catechin of the tea plant, Camellia sinensis, and green tea is by far its most important dietary source. Catechins make up roughly 70% of green-tea polyphenols, and ECG is one of the four principal members — the usual abundance order being EGCG > EGC > ECG > EC, so ECG is typically the second-most-abundant galloylated catechin after EGCG ^{12Reference 12Moore RJ et al. · 2009Green tea (Camellia sinensis) catechins and vascular functionView study →}. Because catechins are oxidised during the manufacture of black and oolong tea — polymerising into theaflavins and thearubigins — green (unoxidised) tea carries the most monomeric ECG, black tea the least, with oolong intermediate ^{12,13Reference 12Moore RJ et al. · 2009Green tea (Camellia sinensis) catechins and vascular functionView study →Reference 13Chan EWC et al. · 2011Antioxidant and antibacterial properties of green, black, and herbal teas of Camellia sinensisView study →}.

Beyond tea, ECG and closely related galloylated flavan-3-ols are reported from a scatter of other plants — for example the leaves of some Hibiscus (roselle) species, where it was the AMPK-active constituent studied above ^{9Reference 9Lin HH et al. · 2025In vitroAMPK-targeting effects of (−)-epicatechin gallate from Hibiscus sabdariffa Linne leaves on dual modulation of hepatic lipid accumulation and glycogen synthesis in an in vitro oleic acid modelView study →}, and various Camellia relatives and persimmon. Quantitative, well-cited figures for ECG content outside green tea are sparse, and even within tea the per-cup ECG figure varies widely with cultivar, leaf age, shade-growing, brewing temperature and steep time — precise source concentrations are tracked as a gap for a later pass.

Discovery & Synthesis

ECG entered the record as part of the chemistry of tea catechins worked out through the first half of the twentieth century, as analysts resolved green tea’s flavan-3-ol fraction into the non-gallated catechins (catechin, epicatechin, gallocatechin, epigallocatechin) and their C-3 galloyl esters (ECG, EGCG and relatives). The molecule is a naturally occurring ester — (−)-epicatechin joined to gallic acid at the 3-hydroxyl — and its name is simply that description: epicatechin-3-gallate.

Manufacture today is overwhelmingly by extraction and chromatographic purification from green tea, the same feedstock that yields EGCG; galloylated catechins can also be prepared semi-synthetically by galloylating epicatechin, a route used to make hydrolytically stable analogues for the antibacterial work ^{4Reference 4Stapleton PD et al. · 2006Potentiation of catechin gallate-mediated sensitization of Staphylococcus aureus to oxacillin by nongalloylated catechinsView study →}. Commercial ECG is a purified tea constituent, not a bulk synthetic.

Patents: not yet researched.

Toxicity & Safety

As a dietary green-tea catechin, ECG carries a low flag: it has been consumed in tea for as long as tea has been drunk, and no distinctive isolate toxicity is characterised for it. The cautions below are largely class-level (green-tea catechins / galloyl polyphenols) rather than ECG-specific, and the notable ones belong more to its sibling EGCG than to ECG itself.

Safety at a Glance

✅ Low / no toxicity

• A normal constituent of a widely-consumed beverage. ECG is one of green tea’s four main catechins and part of ordinary dietary exposure ^{12Reference 12Moore RJ et al. · 2009Green tea (Camellia sinensis) catechins and vascular functionView study →}.
• The high-dose green-tea-extract hepatotoxicity signal is chiefly EGCG’s. Concentrated catechin extracts taken on an empty stomach have been linked to rare liver injury; this caution is driven by EGCG, with ECG-specific data sparse — but it argues against high-dose isolated-catechin supplementation without oversight.
• Galloyl polyphenols bind proteins and non-heme iron. ECG’s strong protein binding underlies tea astringency and can reduce absorption of non-heme (plant) iron when tea is taken with meals — relevant to those managing iron-deficiency.
• Isolate safety is uncharacterised. No dedicated repeat-dose, genotoxicity or reproductive dataset exists for pure ECG; absence of data is not evidence of safety.

Interactions and populations. Because systemic ECG exposure from tea is low, documented drug interactions are for green tea / catechin extracts rather than the isolate; the general green-tea cautions (additive effects with other catechin sources, the iron-absorption point, and the concentrated-extract hepatotoxicity signal) carry over. No CYP/transporter interaction is established for ECG specifically at dietary exposure.

Pregnancy and lactation are a per-herb / per-supplement decision and are not adjudicated on this molecule page; dietary green-tea intake is generally considered acceptable in moderation, but no isolate-specific verdict is issued here.

Dosage

There is no established or recommended human dose for isolated ECG. Human exposure is dietary — ECG is one catechin within the total catechin fraction of green tea (a few to tens of milligrams per cup, alongside EGCG, EGC and EC), and this fraction falls in black and oolong tea where catechins are oxidised ^{12,13Reference 12Moore RJ et al. · 2009Green tea (Camellia sinensis) catechins and vascular functionView study →Reference 13Chan EWC et al. · 2011Antioxidant and antibacterial properties of green, black, and herbal teas of Camellia sinensisView study →}. Research figures are not convertible to self-dosing:

These are research figures and established dietary context, not a personal recommendation.

References

1. Stapleton PD, Shah S, Anderson JC, Hara Y, Hamilton-Miller JMT, Taylor PW (2004). Modulation of beta-lactam resistance in Staphylococcus aureus by catechins and gallates. International Journal of Antimicrobial Agents. https://pubmed.ncbi.nlm.nih.gov/15120724/
2. Stapleton PD, Shah S, Ehlert K, Hara Y, Taylor PW (2007). The beta-lactam-resistance modifier (−)-epicatechin gallate alters the architecture of the cell wall of Staphylococcus aureus. Microbiology (Reading). https://pubmed.ncbi.nlm.nih.gov/17600054/
3. Bernal P, Lemaire S, Pinho MG, Mobashery S, Hinds J, Taylor PW (2010). Insertion of epicatechin gallate into the cytoplasmic membrane of methicillin-resistant Staphylococcus aureus disrupts penicillin-binding protein (PBP) 2a-mediated beta-lactam resistance by delocalizing PBP2. Journal of Biological Chemistry. https://pubmed.ncbi.nlm.nih.gov/20516078/
4. Stapleton PD, Shah S, Hara Y, Taylor PW (2006). Potentiation of catechin gallate-mediated sensitization of Staphylococcus aureus to oxacillin by nongalloylated catechins. Antimicrobial Agents and Chemotherapy. https://pubmed.ncbi.nlm.nih.gov/16436737/
5. Terao J, Piskula M, Yao Q (1994). Protective effect of epicatechin, epicatechin gallate, and quercetin on lipid peroxidation in phospholipid bilayers. Archives of Biochemistry and Biophysics. https://pubmed.ncbi.nlm.nih.gov/8311465/
6. Caturla N, Vera-Samper E, Villalaín J, Mateo CR, Micol V (2003). The relationship between the antioxidant and the antibacterial properties of galloylated catechins and the structure of phospholipid model membranes. Free Radical Biology and Medicine. https://pubmed.ncbi.nlm.nih.gov/12633742/
7. Zhu M, Pan J, Hu X, Zhang G (2021). Epicatechin gallate as xanthine oxidase inhibitor: inhibitory kinetics, binding characteristics, synergistic inhibition, and action mechanism. Foods. https://pubmed.ncbi.nlm.nih.gov/34574301/
8. Wu X, Zhang G, Hu X, Pan J, Liao Y, Ding H (2019). Inhibitory effect of epicatechin gallate on protein glycation. Food Research International. https://pubmed.ncbi.nlm.nih.gov/31229076/
9. Lin HH, Wu PT, Liang YH, Lee MS, Chen JH (2025). AMPK-targeting effects of (−)-epicatechin gallate from Hibiscus sabdariffa Linne leaves on dual modulation of hepatic lipid accumulation and glycogen synthesis in an in vitro oleic acid model. International Journal of Molecular Sciences. https://pubmed.ncbi.nlm.nih.gov/40806739/
10. Braicu C, Pilecki V, Balacescu O, Irimie A, Berindan Neagoe I (2011). The relationships between biological activities and structure of flavan-3-ols. International Journal of Molecular Sciences. https://pubmed.ncbi.nlm.nih.gov/22272136/
11. Lee MJ, Maliakal P, Chen L, Meng X, Bondoc FY, Prabhu S, Lambert G, Mohr S, Yang CS (2002). Pharmacokinetics of tea catechins after ingestion of green tea and (−)-epigallocatechin-3-gallate by humans: formation of different metabolites and individual variability. Cancer Epidemiology, Biomarkers & Prevention. https://pubmed.ncbi.nlm.nih.gov/12376503/
12. Moore RJ, Jackson KG, Minihane AM (2009). Green tea (Camellia sinensis) catechins and vascular function. British Journal of Nutrition. https://pubmed.ncbi.nlm.nih.gov/19751534/
13. Chan EWC, Soh EY, Tie PP, Law YP (2011). Antioxidant and antibacterial properties of green, black, and herbal teas of Camellia sinensis. Pharmacognosy Research. https://pubmed.ncbi.nlm.nih.gov/22224051/

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