Castalagin (Oak C-Glucosidic Ellagitannin · Barrel-Ageing Tannin)

Compound	Castalagin
Chemical class	Tannin — C-glucosidic ellagitannin (open-chain glucose; NHTP + HHDP units)
CAS	24312-00-3
Primary source	Quercus spp. (oak) and Castanea sativa (chestnut) heartwood
Key applications	Barrel-ageing tannin (colour, astringency, bitterness); wood durability; enzyme-inhibition research
Claim strength	Moderate (technological); Emerging (bioactivity)
Typical form	Oak/chestnut heartwood ellagitannin extract (availability on request)
Buy from Herbuno	Availability on request — request bulk pricing →

Name origin: Castalagin takes its name from Castanea, the chestnut genus, and is a C-glucosidic ellagitannin — a structural type distinguished by an open-chain glucose core joined through a carbon-carbon bond to a nonahydroxyterphenoyl (NHTP) unit, rather than the closed pyranose ring and ester linkages of the ordinary ellagitannins. It is the C-1 diastereomer of vescalagin, differing only in the configuration at that single centre. Traditional use: Castalagin has no medicinal tradition of its own, but it has an old and important technological one. Oak heartwood has been used for wine and spirit barrels for centuries, and castalagin and vescalagin are the compounds extracted from the wood into the maturing liquid; they contribute to colour, astringency, and bitterness, and they are part of why oak was historically found to be the only wood that improved wine Michel 2020. They also confer the high natural durability of oak timber. Research trajectory: Vescalagin and castalagin were, fifty years ago, the first C-glucosidic ellagitannin monomers isolated from Castanea and Quercus wood, and the pair have been intensively characterised since. Ellagitannins are the main extractible phenolic compounds of oak heartwood, reaching up to 10% of dry weight, with castalagin and vescalagin the principal monomers alongside grandinin, roburin E, and the dimeric roburins; a validated LC-QQQ method now quantifies them through barrel ageing Michel 2020. Their stereochemistry has been reinvestigated and corrected in the modern literature Quideau (Org Lett), and they have been evaluated, alongside galloylated glucoses, for alpha-glucosidase and alpha-amylase inhibition as potential functional food ingredients Cardullo 2020. Commercial source: Oak or chestnut heartwood ellagitannin extract is available from Herbuno on request.

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Evidence for Castalagin Applications

Barrel-ageing chemistry: Ellagitannins are the principal extractible phenolics of oak wood, present at up to 10% of heartwood dry weight, and castalagin and vescalagin are the main monomers; they are progressively extracted from the wood during ageing, contribute to the colour, astringency, and bitterness of wines and spirits, and are responsible for the durability of the wood itself Michel 2020. This is the compound's best-established and most economically significant role. Claim strength: Moderate (technological).

Analytical quantification: A validated LC-triple-quadrupole method identifies and quantifies oak ellagitannins — castalagin, vescalagin, grandinin, roburin E, and the roburin dimers — in oak wood and in Cognac through barrel ageing, providing the analytical basis for controlling this chemistry in practice Michel 2020. Claim strength: Moderate.

Structural definition: Castalagin is the C-1 diastereomer of vescalagin, and the stereochemistry of both C-glucosidic ellagitannins has been reinvestigated and revised in the modern literature, establishing their configurations definitively Quideau (Org Lett). Claim strength: Moderate.

Carbohydrase inhibition: Castalagin has been studied among fourteen C-glucosidic ellagitannins and three galloylated glucoses for alpha-glucosidase and alpha-amylase inhibition, an investigation of these hydrolysable tannins as potential functional food ingredients with antidiabetic properties Cardullo 2020. These are in vitro enzyme studies, not clinical findings. Claim strength: Emerging.

Reactive chemistry: Castalagin and vescalagin polymerise and form complexes with anthocyanins and flavonoids; the flavono-ellagitannin acutissimin A, for instance, arises when vescalagin reacts with the flavan-3-ol catechin, chemistry directly relevant to how oak tannins interact with grape polyphenols during wine ageing. Claim strength: Emerging.

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Dosage & Formulator Specification

Castalagin has no established human dosing and is not offered as a purified compound. Its evidence base is predominantly technological — concerning wood, wine, and spirits — rather than nutritional, and the bioactivity data are early-stage in vitro enzyme work. Any positioning as a functional ingredient would be well ahead of the evidence.

A source distinction matters here and is a genuine sourcing trap. Castalagin is a heartwood ellagitannin of oak and chestnut. Herbuno's Majuphal product is Quercus infectoria gall extract — the same genus, but a completely different tissue and a different chemistry: galls are gallotannin (tannic acid) material, dominated by galloylglucoses and gallic acid, not the C-glucosidic heartwood ellagitannins. A buyer specifying "Quercus extract" and expecting castalagin would receive the wrong material. Oak or chestnut heartwood ellagitannin extract, standardised to C-glucosidic ellagitannins, is available from Herbuno on request.

For material specification, total C-glucosidic ellagitannins by HPLC or LC-MS is the appropriate measure, with castalagin and vescalagin quantified individually where the application requires it. Toasting is a further variable that formulators of wood-derived material must control: heat treatment of oak generates new C-glycosidic ellagitannins and degrades others, and the resulting profile depends on both toasting intensity and wood piece size, which materially changes the astringency and bitterness the material contributes.

This monograph documents castalagin as a formulator reference within the HerbIQ index, distinguishing heartwood C-glucosidic ellagitannins from gall-derived gallotannins, and connecting it to vescalagin (its diastereomer), the galloylglucoses, and the wider ellagitannin group covered elsewhere.

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Frequently Asked Questions — Castalagin

What is castalagin?
Castalagin is a C-glucosidic ellagitannin of oak and chestnut heartwood. It is the C-1 diastereomer of vescalagin, and the two are the principal ellagitannin monomers extracted from oak barrels into wine and spirits during barrel ageing.

Where does castalagin come from?
Oak (Quercus) and chestnut (Castanea) heartwood, where ellagitannins can reach up to 10% of dry weight. Castalagin and vescalagin were the first C-glucosidic ellagitannin monomers isolated from these woods, and they are also reported from the stem bark of some Terminalia species.

Can I source castalagin from Herbuno?
Oak or chestnut heartwood ellagitannin extract standardised to C-glucosidic ellagitannins is available on request. Note that Herbuno's Majuphal product is Quercus infectoria gall extract, which is gallotannin (tannic acid) material rather than heartwood C-glucosidic ellagitannin, and does not deliver castalagin.

What is castalagin studied for?
Its best-established role is technological: castalagin and vescalagin are extracted from oak into wine and spirits during ageing, where they contribute to colour, astringency, and bitterness, and confer durability on the wood itself. Castalagin has also been examined among C-glucosidic ellagitannins for alpha-glucosidase and alpha-amylase inhibition.

Related compounds: Vescalagin, Galloylglucose, Ellagic Acid, Casuarictin

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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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