Sterubin (Eriodictyol Methyl Ether · Neuroprotective · Ageing Neuron)

Compound	Sterubin (Eriodictyol 7-Methyl Ether; 3′,4′,5-Trihydroxy-7-methoxyflavanone)
Chemical class	Polyphenol — Flavanone (eriodictyol with C-7 O-methylation; Yerba Santa characteristic flavanone)
CAS	3145-22-4
Primary source	Eriodictyon californicum (Yerba Santa / California holy herb)
Key applications	Neuroprotective (aged neurons); ferroptosis inhibition; Alzheimer's research; antioxidant
Claim strength	Moderate (preclinical); Emerging (clinical)
Typical form	Eriodictyon californicum leaf extract; sterubin alongside eriodictyol and homoeriodictyol; not commercially standardised
Buy from Herbuno	Availability on request — request bulk pricing →

Name origin: Sterubin is named after Eriodictyon californicum's resinous leaf coating constituents — the "steryl" fraction of Yerba Santa. It is eriodictyol's 7-methyl ether — the single O-methylation at C-7 of the A-ring distinguishes sterubin from eriodictyol (free 7-OH) and from sakuranetin (naringenin 7-methyl ether, lacking eriodictyol's 3′-hydroxyl). Traditional use: Sterubin, like eriodictyol, is a constituent of Yerba Santa (Eriodictyon californicum) — the California chaparral herb used by indigenous peoples and 19th-century American Eclectic physicians for respiratory conditions, cough, and as a flavour masker. Sterubin contributes to the plant's complex resinous flavanone profile alongside eriodictyol and homoeriodictyol. Research trajectory: Sterubin gained specific scientific attention through a 2019 Salk Institute publication (Bhatt et al., Aging Cell) that systematically screened natural compounds for activity in aged neuron models — cells that are inherently more resistant to rescue than young neurons and that better model the cellular environment of Alzheimer's disease and age-related neurodegeneration. Sterubin emerged as the most neuroprotective compound screened, outperforming eriodictyol and all other Yerba Santa flavanones in aged (but not young) neuron models. This aged-neuron-specific neuroprotective profile is scientifically distinctive. Commercial source: Sterubin is not available as a standardised commercial extract; availability on request for specialty applications.

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Evidence for Sterubin Applications

Neuroprotection in aged neurons (landmark finding): Bhatt et al. (2019, Aging Cell) demonstrated that sterubin at 0.1–1 μM protects aged rat cortical neurons against oxytosis/ferroptosis — two cell death pathways implicated in Alzheimer's and age-related neurodegeneration — with potency superior to eriodictyol, quercetin, resveratrol, and other benchmark compounds in the same aged neuron assay. Crucially, the aged neuron model revealed sterubin's superiority over eriodictyol specifically in this age-relevant cellular context; in young neurons, eriodictyol and sterubin performed similarly. This suggests sterubin's neuroprotection is particularly relevant to the aged-neuron pathological environment. Claim strength: Moderate (strong preclinical; no clinical data yet).

Ferroptosis inhibition: Sterubin's neuroprotective activity in the Salk screen operated primarily through ferroptosis inhibition — a form of regulated cell death driven by iron-dependent lipid peroxidation recently recognised as a major mechanism in Alzheimer's, Parkinson's, and ALS. Sterubin's catechol-containing B-ring (3′,4′-dihydroxy) provides iron chelation capacity suppressing Fenton-type hydroxyl radical generation, while the 7-methyl ether improves membrane penetrance for intracellular delivery to the ferroptosis site. Claim strength: Moderate (preclinical mechanistic).

Antioxidant and Nrf2 induction: Sterubin activates Nrf2/HO-1 signalling in neuronal and hepatocyte models, upregulating endogenous antioxidant enzymes (SOD, GPx, catalase) and GSH synthesis — a cytoprotective response complementing its direct iron chelation and lipid peroxidation inhibition. Claim strength: Moderate.

Anti-inflammatory: NF-κB inhibition and NLRP3 inflammasome suppression are documented for sterubin in macrophage models, consistent with eriodictyol's anti-inflammatory profile but with enhanced potency attributed to the 7-methyl ether's improved membrane access. Claim strength: Emerging.

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Dosage & Formulator Specification

No human supplement dosing data exist for sterubin. The Salk Institute screen identified activity at 0.1–1 μM in cell culture — concentrations achievable in human plasma only with significant oral bioavailability, which has not been formally characterised for sterubin. Allometric dose estimation from preclinical rodent studies suggests effective doses in the range of 50–200 mg/day in humans, but this is speculative without human PK data.

Sterubin is accessible from Yerba Santa leaf extracts alongside eriodictyol and homoeriodictyol. Total flavanone standardisation of Eriodictyon californicum extracts (eriodictyol + sterubin + homoeriodictyol ≥5% combined) is the most achievable commercial specification. Individual sterubin standardisation requires HPLC separation and is available from specialty phytochemical suppliers.

The 7-methyl ether improves sterubin's metabolic stability over eriodictyol — reduced glucuronidation at C-7 extends plasma half-life. However, sterubin's overall oral bioavailability profile (including intestinal absorption, first-pass metabolism) has not been formally characterised in human PK studies. Lipid-based or phospholipid-complexed delivery is recommended based on lipophilicity (logP ~2.6).

No drug interactions are documented for sterubin. The parent plant Yerba Santa has no significant drug interaction profile. Formulators developing sterubin-containing products for Alzheimer's or neuroprotective positioning should communicate the preclinical evidence base clearly and avoid disease-treatment claims.

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Frequently Asked Questions — Sterubin

What made the Salk Institute 2019 finding about sterubin significant?
Most neuroprotective compound screens use young neurons, which are relatively easy to protect. The Salk Institute study (Bhatt et al., Aging Cell 2019) used aged rat cortical neurons — a more disease-relevant model reflecting the cellular environment of the ageing brain. Sterubin outperformed all other tested natural compounds in this aged-neuron context, including established antioxidants and flavonoids like quercetin and resveratrol. The aged-neuron specificity of sterubin's superiority (over eriodictyol in the same screen) suggests a mechanism particularly relevant to age-related neurodegeneration rather than general cellular stress.

What is ferroptosis and why is it important in neurodegeneration?
Ferroptosis is a form of regulated cell death driven by iron-dependent lipid peroxidation — iron catalyses Fenton-type hydroxyl radical generation which oxidises polyunsaturated fatty acids in cell membranes, causing lipid peroxide accumulation and membrane collapse. Ferroptosis was formally described in 2012 (Dixon et al., Cell). Growing evidence implicates ferroptosis as a significant cell death mechanism in Alzheimer's, Parkinson's, Huntington's, and ALS — diseases characterised by iron dysregulation and lipid peroxidation. Sterubin's iron chelation and lipid peroxidation inhibition directly target this pathway.

How does sterubin compare to eriodictyol from the same plant?
Sterubin is eriodictyol's 7-methyl ether — one hydroxyl group is methylated at C-7 of the A-ring. This single modification increases lipophilicity and metabolic stability while, in aged neuron models, producing significantly greater neuroprotective potency than eriodictyol. The C-7 methyl ether improves membrane penetrance and may enhance access to intracellular ferroptosis machinery. In young neurons, both perform similarly; the aged-neuron superiority of sterubin suggests the 7-methyl ether confers advantages specifically relevant to the stressed, iron-dysregulated aged neuron environment.

Is there a clinical trial pathway for sterubin in Alzheimer's disease?
As of the HerbIQ knowledge reference date, no clinical trials for sterubin in Alzheimer's disease have been publicly registered. The Salk Institute's 2019 findings have generated academic and commercial interest; preclinical drug development work is ongoing. Given sterubin's natural origin, simple structure, and apparent safety profile in Yerba Santa's traditional use context, the path to clinical investigation is considered scientifically credible. The timeline for human trials is not established.

Related compounds: Eriodictyol, Bavachin, Sakuranetin, 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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