Caftaric Acid (Hydroxycinnamic Acid Ester · Echinacea Marker)

Compound	Caftaric acid (Caffeoyltartaric acid)
Chemical class	Phenolic acid — Hydroxycinnamic acid ester (caffeic acid + tartaric acid)
CAS	67879-58-7
Primary source	Echinacea purpurea (purple coneflower); Vitis vinifera (grape) — major grape hydroxycinnamate
Key applications	Echinacea marker compound; antioxidant; grape browning chemistry
Claim strength	Moderate (marker/analytical); Emerging (bioactivity)
Typical form	Echinacea purpurea extract standardised to caffeic acid derivatives / polyphenols
Buy from Herbuno	Polyphenols 4% Powder (Echinacea Extract) | Standardized Echinacea purpurea → Purple Coneflower Extract Powder - Echinacea purpurea →

Name origin: Caftaric acid is a portmanteau of caffeic and tartaric — it is simply the caffeic acid ester of tartaric acid, a monocaffeoyltartrate. That structure places it in the hydroxycinnamic acid family alongside chlorogenic acid (caffeic + quinic) and chicoric acid (dicaffeoyltartaric), and it is the mono- counterpart of the di-substituted chicoric acid with which it co-occurs. Traditional use: Caftaric acid has no independent traditional identity but is a defining constituent of two materials with long histories. Echinacea purpurea was used extensively by Native American peoples of the Great Plains for wounds, infections, and snakebite, becoming one of the most widely sold Western herbal products; and grapes, in which caftaric acid is the major hydroxycinnamate, carry their own ancient history in wine. In both, the compound is part of the phenolic matrix rather than a singled-out active. Research trajectory: Caftaric acid is one of the caffeic acid derivatives used to characterise and standardise Echinacea purpurea, and the research that matters most to formulators concerns its instability. Enzymatic degradation studies of E. purpurea preparations demonstrated that the plant's own enzymes attack these compounds — polyphenol oxidase oxidises the catechol ring and esterases hydrolyse the tartaric-caffeic ester bond, so caffeic acid derivatives are lost during processing and storage Nusslein 2000. Work on stabilising these derivatives in E. purpurea glycerin extract showed that the addition of antioxidants substantially improves their retention Bergeron 2002. In grapes, the same catechol-oxidation chemistry makes caftaric acid the primary substrate of enzymatic browning in must and juice. Commercial source: Polyphenols 4% Powder (standardised Echinacea purpurea) is available from Herbuno, with Purple Coneflower Extract Powder as the whole-herb alternative.

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Evidence for Caftaric Acid Applications

Echinacea marker compound: Caftaric acid is among the principal caffeic acid derivatives of Echinacea purpurea and is quantified alongside chicoric acid and caffeic acid when the herb is characterised analytically; studies of extract stability track it explicitly as one of the marker compounds defining product quality Bergeron 2002. Claim strength: Moderate (analytical).

Enzymatic instability — the central formulation issue: Caffeic acid derivatives in E. purpurea preparations are degraded by the plant's own enzymes: polyphenol oxidase oxidises them, and esterases hydrolyse the ester bond between the tartaric and caffeic moieties, producing substantial losses during processing and storage Nusslein 2000. This is not a shelf-life curiosity but the defining practical fact about the compound. Claim strength: Moderate.

Stabilisation by antioxidants: Because the losses are oxidative and enzymatic, they can be countered: addition of antioxidants to an E. purpurea glycerin extract markedly improved the retention of caffeic acid derivatives, demonstrating that the degradation is tractable through formulation rather than being an inevitable property of the material Bergeron 2002. Claim strength: Moderate.

Grape browning chemistry: Caftaric acid is the major hydroxycinnamate of grapes and the principal substrate for polyphenol oxidase in must, making it the compound at the centre of enzymatic browning in juice and wine — the same catechol-oxidation chemistry that degrades it in Echinacea extracts. Claim strength: Moderate.

Antioxidant activity: As a caffeic acid ester bearing the catechol motif, caftaric acid has radical-scavenging capacity typical of the hydroxycinnamates; this is the same structural feature that makes it a good antioxidant and a good oxidase substrate, which is precisely why it is both bioactive and unstable. Claim strength: Emerging.

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Dosage & Formulator Specification

No isolated caftaric acid human dosing standard exists; it is delivered within the caffeic acid derivative fraction of Echinacea purpurea rather than as a standalone compound. The practical specification is total caffeic acid derivatives or total polyphenols by HPLC, with caftaric acid and chicoric acid quantified individually where the application requires a defined profile.

The dominant formulation consideration is stability, and it deserves emphasis because it is frequently underestimated. Echinacea's own polyphenol oxidase and esterase enzymes actively degrade caftaric acid during processing and storage — the oxidase attacks the catechol ring and the esterase cleaves the tartaric-caffeic bond. An Echinacea extract can therefore lose a substantial proportion of its marker compounds between harvest and finished product, which means a certificate of analysis at manufacture is not a guarantee of content at end of shelf life.

Two practical levers follow. First, enzyme inactivation during processing — controlling the conditions under which the fresh plant material is handled — limits the initial losses. Second, antioxidant addition to the finished extract markedly improves retention of the caffeic acid derivatives, a result demonstrated directly in glycerin extracts of E. purpurea. Formulators specifying Echinacea material for a defined caffeic acid derivative content should therefore specify stabilisation, and should require assay at the point of use rather than relying on manufacture-date figures.

Polyphenols 4% Powder (standardised Echinacea purpurea) and Purple Coneflower Extract Powder are available from Herbuno. Caftaric acid also occurs as the major hydroxycinnamate of grape material, where the same oxidase chemistry governs its fate, so grape-derived polyphenol ingredients present a parallel stability profile.

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Frequently Asked Questions — Caftaric Acid

What is caftaric acid?
Caftaric acid is a hydroxycinnamic acid ester — the caffeic acid ester of tartaric acid. It is one of the principal caffeic acid derivatives of Echinacea purpurea and is also the major hydroxycinnamate of grapes and grape juice, where it is central to browning chemistry.

Why does caftaric acid matter for Echinacea extracts?
It is one of the marker caffeic acid derivatives used to characterise Echinacea purpurea, alongside chicoric acid and echinacoside. Critically, it degrades during processing and storage: polyphenol oxidase oxidises it and esterases hydrolyse the tartaric-caffeic ester bond, so extracts lose caffeic acid derivatives unless the extract is stabilised.

Which Herbuno product contains caftaric acid?
Polyphenols 4% Powder (Standardized Echinacea purpurea) delivers caftaric acid within the standardised caffeic acid derivative fraction, and Purple Coneflower Extract Powder (Echinacea purpurea) is the whole-herb alternative. Caftaric acid also occurs in grape material.

How is caftaric acid stabilised?
Because the losses arise from enzymatic oxidation and hydrolysis, stabilisation targets those enzymes. Studies of Echinacea purpurea preparations show that adding antioxidants to the extract markedly improves the retention of caffeic acid derivatives including caftaric acid, and that controlling the enzymatic activity during processing is the decisive factor.

Related compounds: Chicoric Acid, Echinacoside, Caffeic Acid, Chlorogenic Acid

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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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