Caffeic Acid (Hydroxycinnamic Acid · Antioxidant · Anti-inflammatory)

Compound	Caffeic Acid
Chemical class	Polyphenol — Hydroxycinnamic Acid (3,4-Dihydroxycinnamic Acid)
CAS	331-39-5
Primary source	Coffea arabica (coffee), propolis, Echinacea spp., many fruits and vegetables
Key applications	Antioxidant, anti-inflammatory, neuroprotective
Claim strength	Moderate
Typical form	Propolis extract co-constituent; chlorogenic acid hydrolysis product; caffeic acid isolate
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Name origin: From Coffea (coffee) — where it was first characterised as a hydrolysis product of chlorogenic acid. Despite the name, caffeic acid is ubiquitous in the plant kingdom and is one of the most abundant hydroxycinnamic acids in the human diet, present in coffee, fruits, vegetables, and many botanical extracts. Traditional use: Caffeic acid does not have dedicated traditional use as an isolated compound, but plants rich in caffeic acid and its esters (propolis, Echinacea, rosemary) have extensive traditional use for anti-inflammatory, immune-modulating, and antioxidant applications. Research trajectory: Caffeic acid has a well-established preclinical evidence base for antioxidant, anti-inflammatory, antiviral, and neuroprotective activities. Clinical evidence is primarily from dietary exposure studies and propolis/herb preparations; isolated caffeic acid clinical data are limited. Commercial source: Caffeic acid is present as a constituent in propolis extracts, Echinacea preparations, and as a hydrolysis product of green coffee extract (chlorogenic acid → caffeic acid + quinic acid). Isolated caffeic acid is available from specialist suppliers. Contact Herbuno for availability assessment.

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Evidence for Caffeic Acid Applications

Antioxidant capacity: Caffeic acid’s catechol B-ring (3,4-dihydroxy pattern) and α,β-unsaturated carboxylic acid system provide potent radical-scavenging and metal-chelating activity. ORAC and DPPH values are among the highest for simple hydroxycinnamic acids. In vivo antioxidant effects documented in human dietary exposure studies. Claim strength: Moderate.

Anti-inflammatory: Caffeic acid inhibits NF-κB, COX-1/2, and 5-LOX — providing dual cyclooxygenase and lipoxygenase pathway inhibition. The 5-LOX inhibition (relevant to leukotriene production) is a differentiated mechanism among hydroxycinnamic acids. In vivo anti-inflammatory efficacy in animal models is well-documented. Claim strength: Moderate.

Neuroprotective activity: Caffeic acid inhibits MAO-B (monoamine oxidase B), reduces neuroinflammation, and protects dopaminergic neurons in Parkinson’s disease animal models. MAO-B inhibition is relevant for mood and neuroprotective formulations alongside the anti-inflammatory mechanism. Claim strength: Moderate.

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Dosage & Formulator Specification

No established human supplement dose for isolated caffeic acid. Dietary exposure from coffee, fruits, and vegetables provides 50–200 mg/day caffeic acid equivalents in typical Western diets. Preclinical effective concentrations in anti-inflammatory and neuroprotective assays: 10–100 µM. For supplement formulations, caffeic acid is most efficiently delivered as a co-constituent of propolis extract, green coffee extract, or Echinacea preparations rather than as an isolated active.

Caffeic acid phenethyl ester (CAPE) — the caffeic acid ester found in propolis — is a highly studied and potent derivative with superior NF-κB inhibitory activity compared to caffeic acid itself. Formulators interested in the caffeic acid mechanism for anti-inflammatory applications should consider propolis extract (standardised to CAPE content) as a more bioavailable and better-evidenced delivery vehicle.

Caffeic acid has moderate water solubility. Stable at acidic to neutral pH. Sensitive to oxidation (catechol group); antioxidant co-formulation (vitamin C, BHT) and nitrogen packaging recommended. Contact Herbuno for isolated caffeic acid availability and specification.

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Frequently Asked Questions — Caffeic Acid

Is caffeic acid related to caffeine?
No — despite the shared etymological root from Coffea. Caffeic acid is a hydroxycinnamic acid (polyphenol class). Caffeine is a methylxanthine alkaloid. They co-occur in coffee but are structurally and pharmacologically unrelated. Caffeic acid has no stimulant activity.

What is caffeic acid phenethyl ester (CAPE) and how does it compare?
CAPE is the phenethyl ester of caffeic acid, found as the primary bioactive in propolis. CAPE has substantially more potent NF-κB inhibitory activity than caffeic acid (IC50 approximately 10-fold lower) and better membrane permeability due to its hydrophobic phenethyl ester group. Propolis extract standardised to CAPE content is generally preferred over isolated caffeic acid for anti-inflammatory supplement applications.

Is caffeic acid a primary active in Echinacea?
Caffeic acid derivatives — particularly chicoric acid (dicaffeoylquinic acid) and caftaric acid (caffeoyl tartaric acid) — are primary markers of Echinacea purpurea quality and contribute to its immunostimulatory activity. Caffeic acid itself is a minor constituent; the ester derivatives are the primary actives for Echinacea immune applications.

Can caffeic acid be used in topical anti-inflammatory formulations?
Yes. Caffeic acid’s NF-κB and COX inhibition, combined with its antioxidant capacity, makes it relevant for topical anti-inflammatory cosmeceuticals. Skin penetration is moderate; esterification (as in CAPE) or nanosuspension formulation improves dermal delivery. Use levels in topical formulations: 0.1–0.5% caffeic acid equivalent.

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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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