18-Beta-Glycyrrhetinic Acid
18-beta-Glycyrrhetinic acid is the pentacyclic triterpene aglycone of glycyrrhizin, the sweet saponin of licorice root. It is obtained by hydrolysing glycyrrhizin to strip its two glucuronic acid units, and the resulting molecule is not sweet, is far less water soluble than the parent, and behaves as a lipophilic active rather than as a sweetener.
The designation 18-beta refers to the stereochemistry at carbon 18. The 18-beta isomer is the naturally occurring form and the one specified in trade; the 18-alpha isomer is produced by isomerisation under alkaline conditions and differs in its properties, so an assay that does not separate the two is inadequate. The compound is best known for its anti-inflammatory and skin-soothing use in cosmetics, and for the fact that it inhibits 11-beta-hydroxysteroid dehydrogenase, which is the mechanism behind the mineralocorticoid effects seen with heavy licorice consumption.
The material is a white to off-white crystalline powder with a high melting point, practically insoluble in water and soluble in ethanol, chloroform and dilute alkali, where the carboxyl group ionises. Cosmetic formulations therefore use the free acid dispersed in an oil phase or, more often, its more soluble salts and esters.
We source bulk 18-Beta-Glycyrrhetinic Acid from top China manufacturers for our partners. The manufacturer is in Jiangsu. A smaller requirement can ship in a combined container with other ingredients.
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- Function
- Plant extract
Specifications
| Item | Specification |
|---|---|
| Appearance | White to off-white crystalline powder, odourless |
| Assay (HPLC, dry basis) | 98.0 percent minimum as 18-beta-glycyrrhetinic acid |
| Identification | Infrared spectrum and HPLC retention conform to reference standard |
| 18-alpha isomer | 1.0 percent maximum |
| Residual glycyrrhizin | 0.5 percent maximum |
| Melting point | 292 to 298 degrees C |
| Specific rotation | Plus 145 to plus 155 degrees, 1 percent in ethanol |
| Loss on drying | 1.0 percent maximum |
| Residue on ignition | 0.5 percent maximum |
| Residual solvents (ethanol) | 5000 mg/kg maximum |
| Lead | 1.0 mg/kg maximum |
| Arsenic | 1.0 mg/kg maximum |
| Total plate count | 1000 cfu/g maximum |
| Salmonella | Absent in 25 g |
Common Markets Grades
The free acid is traded at 95 and 98 percent assay by HPLC, with 18-alpha isomer content specified separately since it is the impurity that matters most. Residual glycyrrhizin from incomplete hydrolysis is the second controlled impurity, because it reintroduces sweetness and the regulatory considerations attached to glycyrrhizin.
The derivatives are commercially more important than the free acid in cosmetics. Dipotassium glycyrrhizinate, the water-soluble salt of glycyrrhizin rather than of the aglycone, is used where an aqueous system is involved, while stearyl glycyrrhetinate and glycyrrhetinyl stearate are oil-soluble esters of the aglycone used in emulsions and anhydrous products. These are distinct articles with their own specifications and are not interchangeable with the free acid. Micronised grades with a stated particle size are used to improve dispersion, and pharmaceutical-grade material with tighter solvent and metal limits is produced separately from cosmetic grade.
Applications
- Soothing and anti-irritant cosmetic creams and lotions for sensitive skin
- After-sun and post-procedure skin care formulations
- Acne and blemish products, where the anti-inflammatory action supports the positioning
- Oral care products including toothpaste and mouth rinses for gum comfort
- Baby care and nappy-area preparations
- Scalp and hair care products aimed at irritation and flaking
- Colour cosmetics with skin-care positioning
- Licorice-derived supplement ingredients, where it is one of the assayed constituents
- Analytical reference standard for licorice authenticity and potency work
China Manufacturers of 18-Beta-Glycyrrhetinic Acid
Top 18-Beta-Glycyrrhetinic Acid manufacturers in China.
Company names and logos are the property of the manufacturers themselves. They are listed here because our own directory records them as producing this ingredient. A listing is not an endorsement by them, and we do not represent them or speak on their behalf.
Regulatory Status
In the United States 18-beta-glycyrrhetinic acid is used principally as a cosmetic ingredient under the general safety and labelling provisions, which do not involve pre-market approval for an ingredient of this kind, and the Cosmetic Ingredient Review panel has assessed glycyrrhetinic acid and its salts and esters as used in cosmetics. It is not the same substance as licorice extract or ammoniated glycyrrhizin, which are the licorice-derived materials listed as generally recognised as safe for food use under 21 CFR 184.1408, so that listing does not cover the isolated aglycone. The FDA has issued consumer advice on the effects of consuming large quantities of black liquorice, which reflects the same mechanism.
In the European Union it is regulated as a cosmetic ingredient under the cosmetic products regulation and appears in the cosmetic ingredient inventory under the INCI name glycyrrhetinic acid. It has no E number and is not an authorised food additive. Where licorice-derived material is used in food, the labelling requirements attaching to glycyrrhizic acid in confectionery and beverages apply to the glycyrrhizin content rather than to the aglycone. JECFA has evaluated glycyrrhizinic acid and its ammonium salt but has not adopted specifications for 18-beta-glycyrrhetinic acid.
Manufacturing Process
Manufacture begins with licorice root extract or with purified glycyrrhizin, most often as monoammonium glycyrrhizinate. The glucuronide linkages are cleaved by hydrolysis, either by heating with dilute mineral acid under reflux, which is the established industrial route, or enzymatically with a beta-glucuronidase where milder conditions are wanted. Acid hydrolysis has to be controlled carefully because prolonged heating in acid, and any excursion into alkaline conditions during work-up, isomerises the 18-beta centre to the 18-alpha form.
The hydrolysate is cooled and the aglycone, which is almost insoluble in water, precipitates and is collected by filtration or centrifugation, then washed free of acid and of the liberated glucuronic acid. Purification is by dissolution in hot ethanol or in dilute alkali followed by carbon treatment to remove colour and reprecipitation with acid, and the crude solid is recrystallised from alcohol, often twice, to bring the 18-alpha isomer and residual glycyrrhizin within specification. The crystals are washed, dried under vacuum, milled to the specified particle size and packed. Derivatives are made from the purified acid on separate lines by esterification with stearyl alcohol or by salt formation.
