Cyanidin-3-Glucoside — C3G (Anthocyanin · Antiviral · Visual Function)

Compound	Cyanidin-3-Glucoside (C3G)
Chemical class	Polyphenol — Anthocyanin (Cyanidin-3-O-β-D-Glucoside)
CAS	7084-24-4
Primary source	Sambucus nigra (elderberry), Rubus spp. (blackberry), Vaccinium spp.
Key applications	Antiviral (elderberry), antioxidant, visual function
Claim strength	Moderate
Typical form	Elderberry extract standardised to C3G; blackberry extract
Buy from Herbuno	Elderberry Extract Powder - Sambucus nigra → Anthocyanins 25% Powder (Elderberry Extract) | Standardized Sambucus nigra →

Name origin: Systematic name — cyanidin with a glucose attached at the C-3 position (3-O-glucoside). Commonly abbreviated C3G or kuromanin. It is the most extensively studied individual anthocyanin, serving as the reference compound in anthocyanin pharmacokinetic and bioavailability research. Traditional use: Elderberry (Sambucus nigra) preparations have centuries of European and North American traditional use for cold, flu, and respiratory infections. Elder flowers and berries were staple ingredients in European folk pharmacopeia. Elderberry syrup prepared from anthocyanin-rich berries is the most common modern preparation. Research trajectory: C3G has the largest dedicated pharmacokinetic dataset of any anthocyanin, and elderberry extract (C3G-standardised) has multiple human RCTs for influenza and common cold symptom reduction — the most clinically supported botanical antiviral application among anthocyanin-rich extracts. Commercial source: Commercially available via elderberry extract at multiple standardisation levels. See sourcing options below.

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Evidence for C3G Applications

Antiviral activity (elderberry): Multiple human RCTs and a systematic review/meta-analysis demonstrate elderberry extract (C3G-standardised) significantly reduces influenza symptom duration (by approximately 4 days) and severity. Mechanisms include inhibition of viral haemagglutinin (reducing cell attachment) and neuraminidase, plus induction of pro-inflammatory cytokines that support antiviral immune response. C3G is identified as a primary active alongside other elderberry polyphenols. Claim strength: Moderate (multiple RCTs; C3G-specific attribution moderate within elderberry complex).

Antioxidant and DNA protection: C3G is one of the most bioavailable anthocyanins; it is absorbed intact in the small intestine and detected in plasma within 30 minutes of consumption. Human supplementation studies show increased plasma antioxidant capacity, reduced DNA oxidative damage (8-OHdG), and reduced lipid peroxidation. Claim strength: High (well-characterised pharmacokinetics; human antioxidant data consistent).

Visual function and retinal protection: C3G regenerates rhodopsin (visual pigment) in retinal rod cells, supporting visual adaptation and reducing visual fatigue. Human studies in office workers and individuals with myopia show C3G supplementation improves dark adaptation speed and reduces eye fatigue scores. Claim strength: Moderate.

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Dosage & Formulator Specification

Elderberry antiviral RCTs: 15 mL elderberry syrup (standardised to C3G, approximately 150–200 mg total anthocyanins) four times daily for influenza. Commercial elderberry extract supplement doses: 500–1000 mg/day elderberry extract at 1–5% total anthocyanins (5–50 mg total anthocyanins/day) for immune support maintenance; higher doses for acute antiviral applications.

Herbuno supplies Elderberry Extract Powder and Anthocyanins 25% Elderberry Extract — the 25% extract is the highest-potency commercial format for C3G-standardised formulations. For visual function applications, specify C3G content by HPLC alongside total anthocyanin content.

C3G pharmacokinetics are the best-characterised among anthocyanins: absorbed intact in the small intestine (not requiring prior hydrolysis), detected in plasma within 15–30 minutes, Tmax 1–2 hours, bioavailability approximately 0.1–1.8% in humans (low absolute bioavailability is typical for anthocyanins). Colonic microbial catabolism produces additional bioactive phenolic metabolites (protocatechuic acid, phloroglucinol). Stable in acidic pH; standard anthocyanin pH management applies in liquid formats.

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Frequently Asked Questions — Cyanidin-3-Glucoside

Why is elderberry one of the best-evidenced botanical antivirals?
Elderberry extract has been evaluated in human RCTs for influenza with consistent results across independent trial groups. The mechanism is multi-target — C3G and other elderberry polyphenols inhibit viral entry (haemagglutinin binding inhibition), viral release (neuraminidase inhibition), and support innate immune cytokine response simultaneously. This multi-mechanism profile reduces the probability of viral resistance development compared to single-target pharmaceutical antivirals.

Should elderberry be avoided during cytokine storm conditions?
This is a contested area. Some researchers raised concern that elderberry’s immunostimulatory cytokine effects could theoretically worsen cytokine storm in severe COVID-19 or influenza. However, the pro-inflammatory cytokines induced by elderberry (TNF-α, IL-1β, IL-6) at supplement doses are within physiological ranges and the extrapolation to clinical cytokine storm is speculative. No human adverse event data support this concern. Standard advisory language for immunocompromised patients or those on immunosuppressants is appropriate; avoiding elderberry in severe hospitalised illness is reasonable caution, not an established contraindication.

What is the difference between elderberry extract standardised to C3G versus total anthocyanins?
C3G is the dominant anthocyanin in elderberry (typically 60–80% of total anthocyanin content), so total anthocyanin standardisation effectively tracks C3G as the primary marker. The difference is analytical: total anthocyanin by pH differential is less specific but more economical; HPLC-confirmed C3G content provides more precise active compound quantification. For premium formulations or antiviral claim substantiation, HPLC-verified C3G content is the stronger specification.

Is elderberry syrup or extract capsule more bioavailable?
Human pharmacokinetic data do not show a consistent bioavailability difference between elderberry syrup and encapsulated dry extract for C3G, when matched for total anthocyanin dose. Syrup may offer faster Tmax (liquid format). Capsule offers more precise dosing and longer shelf life without refrigeration. Format selection should be driven by product positioning (acute antiviral syrups vs daily immune maintenance capsules) rather than bioavailability differences.

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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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