Liquiritin (Flavanone Glycoside · Skin Brightening · Anti-inflammatory)

Compound	Liquiritin
Chemical class	Polyphenol — Flavanone Glycoside (Liquiritigenin-4′-O-glucoside)
CAS	551-15-5
Primary source	Glycyrrhiza glabra, G. uralensis (licorice root)
Key applications	Skin brightening, antidepressant, anti-inflammatory
Claim strength	Moderate
Typical form	Licorice root extract standardised to liquiritin; isolate

Name origin: Directly from Liquiritia (the medieval Latin for licorice, derived from Glycyrrhiza). Liquiritin is the primary flavanone glycoside of licorice root, alongside the triterpene glycyrrhizin. Traditional use: Licorice root is one of the most widely used medicinal plants globally — in TCM (Gan Cao), Ayurveda (Yashtimadhu), and Western herbal medicine. It has been used for gastric ulcers, respiratory complaints, adrenal support, and skin tone modulation. Liquiritin contributes the non-glycyrrhizin flavanone bioactivity. Research trajectory: Liquiritin has gained significant recent research attention for two specific mechanisms: tyrosinase inhibition (skin brightening) and serotonin-dopamine modulating antidepressant effects in animal models. Clinical data are emerging particularly for the skin-brightening application. Commercial source: Herbuno supplies licorice root extract; high-purity liquiritin isolate is available from specialist suppliers.

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Evidence for Liquiritin Applications

Skin brightening and tyrosinase inhibition: Liquiritin inhibits tyrosinase competitively and disperses melanin — a dual mechanism for hyperpigmentation management. Small clinical studies of topical licorice extract (liquiritin-standardised) show significant reduction in ultraviolet-induced pigmentation and melasma scores over 4 weeks. This is one of the better-evidenced botanical skin-brightening mechanisms. Claim strength: Moderate (topical clinical evidence; oral data absent).

Antidepressant and neuromodulatory activity: Animal studies show liquiritin produces antidepressant-like effects in forced swim and tail suspension tests at 20–40 mg/kg oral dose. Mechanisms include serotonin reuptake inhibition and promotion of neuropeptide Y release. Relevant to mood-support botanical formulations. Claim strength: Emerging (animal data only; no human trials).

Anti-inflammatory and gastric protective: Liquiritin suppresses NF-κB and COX-2; animal models of gastric ulcer show mucosal protection consistent with licorice’s traditional gastric application. Mechanism likely involves PGE2 modulation and mucus secretion support. Claim strength: Moderate.

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Dosage & Formulator Specification

For topical skin-brightening applications: licorice root extract standardised to 1–2% liquiritin, at 0.5–2% inclusion in emulsion or serum base, applied twice daily. Clinical studies supporting pigmentation reduction used 2% total licorice extract (liquiritin-containing) in cream base for 4 weeks.

For oral supplement applications (anti-inflammatory, gastric support, mood support context): licorice root extract at 200–500 mg/day, standardised to ≥5% liquiritin by HPLC. DGL (deglycyrrhizinated licorice) extracts are preferred for long-term oral use — glycyrrhizin removal eliminates the pseudoaldosteronism risk associated with high-dose licorice.

Liquiritin is relatively water-soluble (better than most flavanone aglycones) due to the glucose moiety. Stable in standard manufacturing conditions. For topical formulations, pH 4.5–6.0 is optimal for stability; avoid strongly alkaline cosmetic bases.

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Frequently Asked Questions — Liquiritin

Is liquiritin the same as glycyrrhizin in licorice root?
No. Glycyrrhizin is a triterpene saponin and is responsible for licorice’s characteristic sweet taste and the mineralocorticoid (pseudoaldosteronism) risk with high-dose chronic use. Liquiritin is a flavanone glycoside with entirely different structure, targets, and safety profile. DGL preparations remove glycyrrhizin while retaining liquiritin and other flavanones.

How does liquiritin compare to kojic acid for skin brightening?
Both inhibit tyrosinase, but via different mechanisms — liquiritin disperses melanin in addition to enzyme inhibition, offering a complementary dual action. Kojic acid is more potent on a molar basis but has a higher skin sensitisation risk. Licorice extract (liquiritin) is often preferred in cosmetic formulations targeting sensitive skin or where clean-label positioning is prioritised.

Is there a safety concern with long-term liquiritin supplementation?
Isolated liquiritin does not carry the glycyrrhizin-related pseudoaldosteronism risk. However, licorice root extracts containing both glycyrrhizin and liquiritin should be used at DGL-equivalent doses for long-term oral use. Liquiritin-specific toxicology is well-characterised with a favourable safety profile at studied doses.

Can liquiritin be combined with vitamin C (ascorbic acid) for skin brightening?
Yes, and this is a common cosmetic formulation strategy. Liquiritin (tyrosinase inhibition) and vitamin C (ascorbic acid, tyrosinase inhibition + melanin reduction via reductive mechanism) have complementary and potentially synergistic skin-brightening mechanisms. pH optimisation is required — ascorbic acid stability demands pH below 3.5, while liquiritin is stable up to pH 6.0; a compromise buffered formulation around pH 3.5–4.0 is workable.

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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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