L-Epicatechin
[CAS 490-46-0]

Identification

• Classification: Biochemical >> Chinese herbal medicine ingredients
• Name: L-Epicatechin
• Synonyms: 2-(3,4-Dihydroxyphenyl)-3,4-dihydro-2H-1-benzopyran-3,5,7-triol
• Molecular Formula: C₁₅H₁₄O₆
• Molecular Weight: 290.27
• CAS Registry Number: 490-46-0
• EC Number: 207-710-1
• SMILES: C1[C@H]([C@H](OC2=CC(=CC(=C21)O)O)C3=CC(=C(C=C3)O)O)O

Properties

• Density: 1.5±0.1 g/cm³ Calc.^*
• Melting point: 223 - 226 °C (Expl.)
• Boiling point: 707.7±60.0 °C 760 mmHg (Calc.)^*
• Flash point: 381.8±32.9 °C (Calc.)^*
• Index of refraction: 1.737 (Calc.)^*
• Alpha: -77.5 ° (c=0.2, EtOH) (Expl.)

Safety Data

• Hazard Symbols: GHS07 Warning
• Risk Statements: H315-H319-H335
• Safety Statements: P261-P264-P264+P265-P271-P280-P302+P352-P304+P340-P305+P351+P338-P319-P321-P332+P317-P337+P317-P362+P364-P403+P233-P405-P501

Hazard Classification

Hazard	Class	Category Code	Hazard Statement
Skin irritation	Skin Irrit.	2	H315
Eye irritation	Eye Irrit.	2	H319
Specific target organ toxicity - single exposure	STOT SE	3	H335
Specific target organ toxicity - single exposure	STOT SE	3	H336

chemBlink Chemical Story

L-Epicatechin is the (2R,3R) stereoisomer commonly written as (-)-epicatechin. It belongs to the flavan-3-ols and is a constituent of plant materials including tea and cocoa. Its framework has two stereocenters in the central ring. The sign of optical rotation and the R/S descriptors are different kinds of information: one reports the direction of a measurement, while the others specify a configuration. Neither the common name nor a formula alone describes every stereoisomer.

Comparison with catechin illustrates the significance of relative configuration. Epicatechin and catechin can have identical connectivity but a different relationship between substituents at positions 2 and 3. Flipping just one stereocenter does not turn a compound into its mirror image; it produces a diastereomer. Flipping both gives the enantiomer in this two-center example. For a food analysis, these distinctions matter when a method reports one named flavanol rather than a sum of compounds with similar properties.

The monomer is also distinct from larger compounds that contain flavanol units. Joining units changes the size and connectivity of a molecule. A result reported as total flavanols does not necessarily give the amount of free epicatechin, and a complex cocoa preparation cannot be defined by one monomer alone. Differences in starting material and processing make it important to specify what was actually measured.

A 2006 human intervention study by Schroeter and colleagues investigated vascular responses in the context of flavanol-rich cocoa and examined the contribution of (-)-epicatechin. Its value lies in connecting a chemically identified constituent with a measurable response rather than relying on the word antioxidant. The outcome was a vascular function measurement under study conditions, not a direct count of future cardiovascular events. That distinction is also why the work cannot be read as evidence that arbitrary cocoa products or epicatechin supplements provide an equivalent effect.

Epicatechin thus connects two problems of identification. The first is chemical: determine which arrangement of atoms is present. The second is experimental: determine which component and which outcome a study actually tested. Precision at the first level makes the second question possible but does not answer it on its own.

References:
1. PubChem. Epicatechin, CID 72276. https://pubchem.ncbi.nlm.nih.gov/compound/72276
2. Schroeter H et al. Epicatechin and vascular function in a cocoa intervention study. PNAS (2006). https://pubmed.ncbi.nlm.nih.gov/16418281/

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