Eriodictyol (Flavanone · Mucolytic · Anti-inflammatory)

Compound	Eriodictyol (3′,4′,5,7-Tetrahydroxyflavanone; Eriodictiol)
Chemical class	Polyphenol — Flavanone (catechol B-ring flavanone; naringenin 3′-hydroxylated analogue)
CAS	552-58-9
Primary source	Eriodictyon californicum (Yerba Santa / holy herb), Citrus spp. (minor), Salvia officinalis
Key applications	Mucolytic; bitterness-masking; anti-inflammatory; antioxidant; neuroprotective
Claim strength	Moderate
Typical form	Eriodictyon californicum leaf extract; eriodictyol sodium salt (Symrise Sensoril® bitterness masker)
Buy from Herbuno	Availability on request — request bulk pricing →

Name origin: Eriodictyol is named after Eriodictyon californicum — Yerba Santa or "holy herb" in Spanish — a California chaparral shrub in the Boraginaceae family (formerly Hydrophyllaceae). The name Eriodictyon means "woolly net" in Greek, describing the plant's hairy reticulate leaves. Eriodictyol is the dihydroxy aglycone of eriocitrin (eriodictyol-7-rutinoside, abundant in lemon peel) and the 3′-hydroxy analogue of naringenin. Traditional use: Eriodictyon californicum (Yerba Santa) has extensive documented use by California indigenous peoples — the Chumash, Ohlone, and other tribes — as a primary respiratory herb for cough, asthma, and bronchial congestion, taken as leaf infusion or smoked. The plant was adopted into 19th-century American Eclectic medicine as a mucolytic and expectorant, and was official in the US Pharmacopoeia from 1894 to 1947. The characteristic resinous taste of Yerba Santa was exploited as a natural flavour masker in pharmacy — a property of eriodictyol now commercialised as a systematic bitterness-masking ingredient. Research trajectory: Eriodictyol's mucolytic and anti-inflammatory activities reflect the traditional respiratory applications. More recent research has characterised neuroprotective activity in ageing neuron models and identified eriodictyol as an activator of Nrf2 antioxidant pathways. Its bitterness-masking property (via TAS2R bitter taste receptor modulation and trigeminal desensitisation) has been commercially developed by Symrise as Sensoril® Bitter Blocking Technology. Commercial source: Eriodictyol is not currently available as a standardised extract in the Herbuno catalogue; availability on request.

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Evidence for Eriodictyol Applications

Mucolytic and expectorant: Eriodictyol reduces mucus viscosity and enhances mucociliary clearance in respiratory epithelium models by activating purinergic signalling and upregulating aquaporin-mediated airway surface liquid hydration. In isolated tracheal preparations, eriodictyol increases ciliary beat frequency — the primary mechanical mechanism of mucociliary clearance. Traditional Yerba Santa preparations for cough have clinical precedent spanning centuries; isolated eriodictyol mucolytic data are primarily in vitro. Claim strength: Moderate (traditional); Emerging (isolated).

Bitterness masking: Eriodictyol's sodium salt (sodium eriodictyol, or eriodictyol-7-rutinoside preparations) modulates human TAS2R bitter taste receptors — particularly TAS2R14 and TAS2R39 — reducing the perceived bitterness of dietary supplements, pharmaceuticals, and functional foods. This is an established commercial application (Symrise Sensoril®, Givaudan preparations) with food-grade GRAS status in the US. Effective concentrations of 0.005–0.05% in formulation significantly reduce bitterness of common bitter actives (quercetin, caffeine, fish oil, protein hydrolysates). Claim strength: High (food technology application).

Neuroprotective: Eriodictyol has demonstrated neuroprotective activity in hydrogen peroxide, glutamate, and β-amyloid-induced neurotoxicity models, preventing cell death via Nrf2/HO-1 pathway induction and mitochondrial membrane potential stabilisation. In aged hippocampal neuron models, eriodictyol at 10 μM preserved synaptic protein expression — a finding relevant to age-related cognitive decline research. Claim strength: Emerging.

Anti-inflammatory and antioxidant: Eriodictyol's catechol B-ring (3′,4′-dihydroxy) confers excellent radical scavenging activity comparable to quercetin. COX-2 and iNOS inhibition, NF-κB suppression, and NLRP3 modulation are documented in macrophage models. Claim strength: Moderate.

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Dosage & Formulator Specification

Eriodictyol has no established human supplement dosing protocol. Yerba Santa preparations in traditional use involve leaf infusions at 2–5 g dried herb per cup, 2–3 times daily for respiratory applications. Isolated eriodictyol content in Yerba Santa leaf is 1–3% dry weight; other resin constituents (eriodictyone, homoeriodictyol) also contribute to the plant's activities.

For bitterness masking applications — eriodictyol's most commercially developed use — the required concentration is 50–500 ppm (0.005–0.05%) in finished formulation. GRAS (Generally Recognised As Safe) status at these concentrations is established for the sodium salt form. This is not a supplement dosing but a functional food/pharmaceutical formulation application where eriodictyol functions as a flavour modifier.

Eriodictyol's catechol B-ring makes it susceptible to oxidation in aqueous formulations — protective measures include nitrogen packaging, antioxidant co-formulation (vitamin C, tocopherols), and pH maintenance at 4–6. Solid dosage forms (capsule, tablet) offer better shelf stability. Eriocitrin (eriodictyol-7-rutinoside from lemon peel) is a more stable delivery form for mucolytic supplement applications.

No documented herb-drug interactions are established for eriodictyol. The parent plant Yerba Santa has no significant drug interaction profile in traditional use at standard doses.

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Frequently Asked Questions — Eriodictyol

What is Yerba Santa and why was it important in American pharmacognosy?
Yerba Santa (Eriodictyon californicum) is a California chaparral shrub used by indigenous Californian peoples as a primary respiratory medicine and flavour masker. It was listed in the US Pharmacopoeia (1894–1947) as a mucolytic and expectorant, and the Eclectic physicians of the 19th century used it extensively for chronic bronchitis, asthma, and as a flavour masker for quinine and other bitter medicinals. Its traditional bitterness-masking function has been rediscovered commercially in modern flavour technology.

What is the bitterness-masking mechanism of eriodictyol?
Bitter taste is mediated by the TAS2R family of G-protein-coupled receptors (25 human subtypes). Eriodictyol and its derivatives modulate specific TAS2R subtypes (particularly TAS2R14) by either competitive partial agonism (reducing receptor availability for bitter compounds) or downstream signal antagonism — reducing the amplitude of the bitter taste response without altering the sweetness, saltiness, or sourness perceptions. This receptor-level mechanism is distinct from simple taste masking by sweeteners or fats.

How does eriodictyol compare to sterubin in Yerba Santa?
Both eriodictyol (a flavanone) and sterubin (eriodictyol 7-methyl ether — a flavanone methyl ether) are found in Eriodictyon californicum. Sterubin has attracted attention for neuroprotective activity in aged neuron models — particularly a Salk Institute study (2019) showing sterubin more potently protects aged neurons than eriodictyol. Sterubin's 7-methyl ether reduces solubility but improves membrane penetration versus eriodictyol. Both are relevant to Yerba Santa's neuroprotective profile; sterubin may be more potent for CNS applications.

Is eriocitrin a better supplement source than eriodictyol?
Eriocitrin (eriodictyol-7-rutinoside) is the primary Citrus lemon peel flavanone — more commercially available than isolated eriodictyol and with better aqueous stability due to the rutinoside sugar. After gut microbial deglycosylation, eriocitrin releases eriodictyol for absorption. For respiratory and antioxidant supplement applications, eriocitrin from lemon peel extract is a more practical and accessible delivery form than isolated eriodictyol from Yerba Santa.

Related compounds: Naringin, Hesperetin, Sterubin, Naringenin

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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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