Epicatechin Gallate — ECG (Flavan-3-ol Gallate · Antimicrobial · Antioxidant)

Compound	Epicatechin Gallate (ECG)
Chemical class	Polyphenol — Flavan-3-ol Gallate
CAS	1257-08-5
Primary source	Camellia sinensis (green tea leaves)
Key applications	Antimicrobial, antioxidant, lipid modulation
Claim strength	Moderate
Typical form	Green tea extract (co-delivered with EGCG and other catechins)

Name origin: ECG is the gallated form of epicatechin — epicatechin with a gallic acid ester at the C-3 hydroxyl. It is the second most abundant gallated catechin in green tea after EGCG. Traditional use: As a co-constituent of green tea, ECG shares the broad traditional use context of Camellia sinensis preparations. It has not been singled out in traditional medicine; its individual bioactivity profile has been defined through modern phytochemical research. Research trajectory: ECG has a meaningful preclinical evidence base, particularly for antimicrobial activity against antibiotic-resistant bacteria and for lipid-lowering mechanisms. Clinical evidence is limited as most green tea trials do not individualise ECG effects from the overall catechin fraction. Commercial source: Supplied as a co-constituent of green tea extract; isolated ECG is available from specialist suppliers as a research-grade material.

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Evidence for ECG Applications

Antimicrobial and anti-MRSA activity: ECG demonstrates potent inhibitory activity against Staphylococcus aureus including MRSA, with MIC values comparable to EGCG. The mechanism involves disruption of bacterial cell membrane integrity and inhibition of penicillin-binding protein 2a (PBP2a) — the resistance determinant in MRSA. ECG has been studied as a potential adjuvant to restore beta-lactam antibiotic sensitivity. Claim strength: Moderate (in vitro and animal; no human clinical antibiotic trials).

Antioxidant and lipid peroxidation inhibition: ECG has comparable antioxidant capacity to EGCG in DPPH and ORAC assays. The gallate moiety contributes substantially to radical-scavenging activity. ECG inhibits LDL oxidation in vitro, supporting its inclusion in cardiovascular antioxidant formulations. Claim strength: Moderate.

Lipid metabolism: ECG inhibits pancreatic lipase activity in vitro, suggesting a fat absorption-reducing mechanism relevant to weight management. This effect is shared across gallated catechins; ECG and EGCG are the most potent inhibitors. Human clinical translation is limited. Claim strength: Emerging.

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Dosage & Formulator Specification

ECG is not formulated as a standalone supplement. It is co-delivered via green tea extract at approximately 5–15% of total catechin content depending on extraction method and tea variety. In a 400 mg dose of EGCG 50% green tea extract (800 mg extract), ECG content is typically 40–120 mg.

For antimicrobial oral health applications, green tea extract inclusion in lozenges, mouthwash, or chewing gum delivers ECG alongside EGCG at concentrations relevant to oral pathogen inhibition. Typical effective concentrations in oral care formats: 0.1–0.5% total catechins, providing ECG at relevant antimicrobial exposure levels.

ECG stability is similar to EGCG — sensitive to oxidation and alkaline pH. Gallate ester bond is susceptible to enzymatic hydrolysis by esterases in the gut, converting ECG to epicatechin and gallic acid — both bioactive. This hydrolysis is considered beneficial for overall catechin exposure.

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Frequently Asked Questions — ECG

How does ECG differ from EGCG?
EGCG has a trihydroxylated gallocatechin backbone (with three hydroxyl groups on the B-ring); ECG has a dihydroxylated catechin backbone (two hydroxyls on the B-ring). Both carry the C-3 gallate ester. EGCG has stronger overall bioactivity in most assays due to the additional B-ring hydroxyl group; ECG has comparable antimicrobial activity and lipase inhibition.

Is ECG content declared on green tea extract certificates of analysis?
Yes, in full catechin profile CoAs. A complete green tea catechin panel should report: EGCG, ECG, EGC (epigallocatechin), EC (epicatechin), catechin (C), and gallocatechin (GC) individually by HPLC. Total catechin content alone does not tell you the ECG fraction; request the full profile for formulations where ECG is a relevant active.

Can ECG from green tea extract serve as a preservative in food applications?
Green tea extract (including ECG) has documented antimicrobial activity relevant to food preservation, and is used as a natural preservative in some markets. Regulatory status as a food preservative varies; it is generally recognised as a flavouring or botanical ingredient rather than a declared preservative in most markets.

Does ECG have lower bioavailability than EGCG?
Pharmacokinetic studies suggest comparable peak plasma concentrations for ECG and EGCG after equal oral doses, though EGCG is typically present in higher absolute amounts in tea extracts. Both undergo gut microbial and hepatic phase II conjugation. ECG’s gallate ester is partially hydrolysed in the gut, generating epicatechin and gallic acid as additional bioactive species.

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Claim-strength scale – High = multiple human RCTs; Moderate = limited trials or strong preclinical convergence; Emerging = early-stage lab or animal data.

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