Glabridin (Isoflavan · Tyrosinase Inhibition · Skin Brightening)

Compound	Glabridin
Chemical class	Polyphenol — Isoflavan (Licorice Isoflavan)
CAS	59870-68-7
Primary source	Glycyrrhiza glabra (licorice root)
Key applications	Skin brightening, tyrosinase inhibition, anti-inflammatory
Claim strength	Moderate
Typical form	Licorice root extract standardised to glabridin content
Buy from Herbuno	Licorice Root Extract Powder | Mulethi → DGL Licorice Extract Powder | Mulethi →

Name origin: From Glycyrrhiza glabra (glabra = smooth-leaved licorice species), reflecting its primary botanical source. Glabridin is an isoflavan — the reduced form of the isoflavone scaffold (no C2=C3 double bond, no C4 carbonyl), which places it in a structurally distinct subclass from genistein and daidzein despite shared isoflavonoid heritage. Traditional use: Licorice root has extensive multi-cultural traditional use (TCM, Ayurveda, European phytomedicine) for gastric, respiratory, and endocrine applications. Glabridin contributes a distinct bioactivity profile separate from glycyrrhizin (the triterpene saponin) and liquiritin (the flavanone glycoside) — specifically for skin and inflammatory applications. Research trajectory: Glabridin is well-researched for tyrosinase inhibition and skin brightening, with documented cosmeceutical applications. Anti-inflammatory (NF-κB) and phytoestrogenic activities provide additional formulation positioning. Commercial source: Glabridin is commercially available as a co-constituent of licorice root (Glycyrrhiza glabra) extract and DGL (deglycyrrhizinated licorice) extract; isolated glabridin is available at 40% and 90% purity from specialist suppliers. See sourcing options below.

---

Evidence for Glabridin Applications

Tyrosinase inhibition and skin brightening: Glabridin is one of the most potent natural tyrosinase inhibitors characterised, with IC50 values in the low micromolar range. It inhibits both DOPA oxidase and diphenol oxidase activities of tyrosinase, blocking melanin synthesis at multiple steps. Human clinical studies of topical licorice extract (glabridin-standardised) show significant reduction in UV-induced hyperpigmentation and melasma over 4–8 weeks. Claim strength: Moderate (topical clinical evidence; oral data emerging).

Anti-inflammatory and NF-κB suppression: Glabridin inhibits NF-κB, COX-1, COX-2, and superoxide anion production across macrophage and skin cell models. In animal models, topical glabridin reduces UV-induced erythema and inflammation. Relevant for anti-inflammatory cosmeceutical and oral supplement formulations. Claim strength: Moderate.

Phytoestrogenic activity: Glabridin is an ERβ agonist, with estrogenic potency approximately 1/1000th of oestradiol. Animal studies suggest bone-protective and cardiovascular effects similar to other phytoestrogenic isoflavonoids. Human phytoestrogenic clinical data for isolated glabridin are limited. Claim strength: Emerging.

---

Dosage & Formulator Specification

Topical skin-brightening applications: licorice extract standardised to 0.5–2% glabridin, included at 0.5–2% in the finished cosmetic formulation. Clinical studies on hyperpigmentation used 0.5% licorice extract gel applied twice daily for 4 weeks.

Oral anti-inflammatory/phytoestrogenic applications: licorice root extract at 300–600 mg/day standardised to glabridin content (typically 1–3% glabridin). DGL (deglycyrrhizinated licorice) extracts are preferred for oral long-term use to avoid glycyrrhizin-related pseudoaldosteronism risk; DGL preparations retain glabridin content.

Glabridin has very low aqueous solubility (~0.02 mg/mL); solubilisation is critical for topical and oral liquid formats. Cyclodextrin complexation, phospholipid complexation, or nanosuspension are established approaches. Stable at neutral-to-acidic pH; sensitive to UV light and oxidation — specify antioxidant co-formulation and opaque packaging.

---

Frequently Asked Questions — Glabridin

How does glabridin compare to kojic acid and arbutin for skin brightening?
All three inhibit tyrosinase, but by different mechanisms and with different safety profiles. Glabridin: competitive inhibition, excellent skin tolerability, natural botanical origin. Kojic acid: chelation of copper at the tyrosinase active site, more potent but higher sensitisation risk. Arbutin: substrate analogue, hydroquinone precursor (which has regulatory concerns in some markets). Glabridin is preferred for clean-label, sensitive-skin, and natural formulation positioning.

Is glabridin content preserved in DGL licorice extract?
DGL (deglycyrrhizinated licorice) is processed specifically to remove glycyrrhizin (the mineralocorticoid-active triterpene). The deglycyrrhizination process targets the triterpene fraction and does not significantly deplete the flavonoid/isoflavan fraction. Glabridin content in DGL should be confirmed by HPLC; it is generally preserved at levels comparable to standard licorice extract.

Does glabridin have estrogenic activity that warrants a safety advisory for topical use?
Topical glabridin at cosmetic use levels (0.5–2% extract in formulation) delivers very low systemic exposure due to limited skin penetration. The estrogenic potency is approximately 1/1000th of oestradiol. Systemic estrogenic effects from topical cosmetic use are not considered a practical concern at current evidence levels. Standard INCI listing and concentration disclosure in cosmetic formulations is the appropriate regulatory approach.

Can glabridin be used in combination with vitamin C for enhanced skin brightening?
Yes — a rational and commonly used combination. Glabridin (tyrosinase inhibition at the copper active site) + vitamin C (tyrosinase inhibition + melanin reduction via antioxidant reductive mechanism) provide complementary and potentially additive brightening activity. pH optimisation is required; ascorbic acid demands pH below 3.5 while glabridin is stable to pH 6.0. A buffered formulation around pH 3.5–4.0 is workable.

---

Claim-strength scale – High = multiple human RCTs; Moderate = limited trials or strong preclinical convergence; Emerging = early-stage lab or animal data.

← HerbIQ Compound Index · HerbIQ P02: Extraction · HerbIQ P03: Delivery