Scutellarein (Flavone · Antiviral · Neuroprotective)

Compound	Scutellarein (6-Hydroxyapigenin; 4′,5,6,7-Tetrahydroxyflavone)
Chemical class	Polyphenol — Flavone (apigenin 6-hydroxylated derivative; hydroxylation at unusual C-6 position)
CAS	529-53-3
Primary source	Scutellaria baicalensis (Chinese skullcap root), Scutellaria lateriflora (American skullcap), Erigeron breviscapus
Key applications	Antiviral; neuroprotective; anti-inflammatory; cardiovascular
Claim strength	Moderate
Typical form	Scutellaria baicalensis extract (scutellarein co-delivered alongside baicalein, baicalin, wogonin); Erigeron breviscapus extract
Buy from Herbuno	Baicalein 98% Powder (Chinese Skullcap) | High-Purity Isolate | Scutellaria baicalensis → Baicalin 85% Powder (Chinese Skullcap Extract) | Standardized Scutellaria baicalensis →

Name origin: Scutellarein is named after Scutellaria — the skullcap genus — reflecting its isolation from Chinese and American skullcap species. It is apigenin with an additional hydroxyl group at C-6 of the A-ring — an unusual hydroxylation position compared to the more common C-8 or C-3 hydroxylation patterns in other flavones. Scutellarein is also the aglycone of scutellarin (scutellarein-7-glucuronide), the primary water-soluble flavone of Erigeron breviscapus (dengzhanxixin in TCM). Traditional use: Scutellaria baicalensis (Huang Qin — Chinese skullcap root) is one of the most important herbs in TCM, prescribed for heat-clearing, damp-heat conditions, liver fire, and upper respiratory tract infections. It is a core herb in classical formulas such as Huang Qin Tang (for GI infections) and San Huang Xie Xin Tang (for hypertension and inflammatory conditions). Scutellarein is a minor constituent of Huang Qin alongside the more abundant baicalin, baicalein, and wogonin. Erigeron breviscapus (fleabane), used in Chinese folk medicine for stroke rehabilitation and cerebrovascular disease, is a richer source of scutellarein (as scutellarin). Research trajectory: Scutellarein has been studied for antiviral activity (particularly flavivirus inhibition), neuroprotection, and anti-inflammatory activity. Its 6-hydroxyl group creates a distinct substitution pattern that modulates receptor binding differently from baicalein (6,7-dihydroxy) and apigenin. Commercial source: Scutellarein is available from Herbuno via Baicalein 98% Powder (Chinese Skullcap) and Baicalin 85% Powder — Scutellaria baicalensis standardised extracts that co-deliver scutellarein as part of the flavone spectrum.

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Evidence for Scutellarein Applications

Antiviral activity: Scutellarein and its glucuronide scutellarin demonstrate antiviral activity against dengue virus, Zika virus, influenza A, and hepatitis C in cell-based assays. Mechanisms include NS5 polymerase (RdRp) inhibition for flaviviruses and haemagglutinin-mediated cell entry blockade for influenza. In dengue models, scutellarein IC₅₀ values of 10–40 μM are comparable to established antiviral reference compounds in vitro. Claim strength: Moderate.

Neuroprotective: Scutellarein and scutellarin have been evaluated clinically in China for cerebrovascular disease (Erigeron breviscapus injection — Dengzhanhuasu — is a CFDA-approved injection for acute ischaemic stroke supportive treatment). The mechanism involves NADPH oxidase inhibition reducing oxidative stress in ischaemic neurons, CXCL12/CXCR4 pathway modulation promoting neural repair, and inflammatory microglial suppression. Isolated scutellarein oral neuroprotective data are preclinical. Claim strength: Moderate (scutellarin IV); Emerging (oral scutellarein).

Anti-inflammatory: NF-κB, COX-2, and iNOS inhibition are well-documented for scutellarein in macrophage models at 10–50 μM. NLRP3 inflammasome suppression has been characterised in recent studies, contributing to its relevance for chronic inflammatory condition research. Claim strength: Moderate.

Cardiovascular: Scutellarein inhibits platelet aggregation, reduces vascular smooth muscle proliferation, and improves endothelial NO production in vascular models. In the context of Erigeron breviscapus clinical use for cerebrovascular disease in China, cardiovascular benefits of the parent scutellarin are established at the traditional use level. Claim strength: Moderate (traditional/regulatory); Emerging (isolated).

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Dosage & Formulator Specification

No human supplement dosing data exist for isolated oral scutellarein. Scutellarin (scutellarein-7-glucuronide) injectable preparations (Dengzhanhuasu Injection) are used in Chinese clinical practice for cerebrovascular disease at 0.1–0.5 g IV per day. The corresponding oral scutellarein dose is not established due to differing bioavailability between IV and oral routes and between the glycoside (scutellarin) and aglycone (scutellarein).

For formulators targeting the Scutellaria flavone spectrum, baicalin-standardised Scutellaria baicalensis root extract (Baicalin 85%, Herbuno) delivers scutellarein alongside baicalin, baicalein, and wogonin at proportions reflecting the natural skullcap alkaloid distribution. Total flavonoid content specification (≥85% baicalin equivalent) is the commercial standard; scutellarein is present at 0.1–1% of the total flavone fraction.

Erigeron breviscapus extract standardised to scutellarin (≥2–5%) is available from Chinese botanical suppliers as a more scutellarein-accessible source. The scutellarin → scutellarein conversion in gut requires glucuronidase activity; bioavailability of scutellarein from oral scutellarin is variable.

No significant herb-drug interactions are documented for scutellarein specifically. The Scutellaria class should be used with appropriate hepatotoxicity monitoring in high-dose or prolonged supplementation contexts (rare hepatotoxicity cases linked to Scutellaria misidentification with Teucrium as an adulterant).

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Frequently Asked Questions — Scutellarein

What is the relationship between scutellarein and scutellarin?
Scutellarin is scutellarein-7-O-glucuronide — the primary flavonoid of Erigeron breviscapus. Gut glucuronidase enzymes hydrolyse scutellarin to release scutellarein aglycone for absorption. Scutellarin is the more commonly referenced clinical compound (used in Chinese IV preparations); scutellarein is the bioactive form generated in vivo and directly in Scutellaria baicalensis root alongside baicalein and wogonin.

How does scutellarein differ from baicalein from the same plant?
Both are Scutellaria flavones: baicalein is 5,6,7-trihydroxyflavone (A-ring with no B-ring hydroxyl); scutellarein is 4′,5,6,7-tetrahydroxyflavone (adds a 4′-B-ring hydroxyl, making it an apigenin C-6 hydroxylated analogue). The 4′-hydroxyl gives scutellarein broader antiviral activity; baicalein's 5,6-catechol system gives stronger iron chelation and 5-LOX selectivity. They are pharmacologically complementary within Scutellaria extract.

Is the Erigeron breviscapus injection used clinically in China?
Yes — Dengzhanhuasu Injection (Erigeron breviscapus extract injection) containing scutellarin is a CFDA-approved pharmaceutical product used in Chinese hospitals for cerebrovascular disease supportive treatment. Multiple clinical studies in Chinese patients have demonstrated safety and some efficacy for stroke recovery parameters. This represents a more advanced clinical evidence base than typical dietary supplement flavonoids, though the IV route and compound-specific pharmacology make direct extrapolation to oral supplementation cautious.

What quality control issue is associated with Scutellaria supplements?
Scutellaria lateriflora (American skullcap) and S. baicalensis products have historically been adulterated with or mis-labelled as Germander (Teucrium species), which contains hepatotoxic diterpenoids. Cases of hepatotoxicity attributed to skullcap are now believed to reflect Teucrium contamination. Authenticated botanical material with HPLC flavonoid fingerprint verification (baicalin, baicalein, wogonin, scutellarein pattern is diagnostic for genuine Scutellaria) eliminates this risk. Herbuno's Scutellaria-derived products should carry full CoA documentation including flavonoid HPLC profiles.

Related compounds: Baicalein, Baicalin, Wogonin, Chrysin

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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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