Botanical Name / Family
Glycyrrhiza glabra L. (family Leguminosae)
It should be differentiated from: G. uralensis (synonyms: Chinese licorice, gan cao, licorice root, sweet root), G. inflata (synonyms: gan cao, zhigancao), G. pralidiflora, G. glandifera, G. pallida, G. tyica and G. violocea, although some studies do not always clearly state which form is used.
Plant Parts Used
Root and stolon
Licorice root has been used in Europe since prehistoric times, and its medicinal use is well documented. References to licorice date backto approximately 2500 BC on Assyrian clay tablets and Egyptian papyri. It has been used as both a food and a medicine since ancient times. The genus name, meaning ‘sweet root’, is attributed to the first century Greek physician Dioscorides. The herb is also popular in traditional Chinese and Ayurvedic medicine.
Licorice contains several triterpenoid saponins, the most studied of which is glycyrrhizin (GL, also known as glycyrrhizic acid or glycyrrhizinic acid).
Other important constituents include: flavonoids (isoflavonoids, liquiritin, isoliquiritin, liquiritigenin, formononetin, glabridin and the chalcones [isoliquiritigenin, licochalcone A and B]); sterols (beta-sitosterol); polysaccharides (arabinogalactans); coumarins (glycerin); glabrol; amines; glucose, sucrose; resin; and volatile oil.
Clinical note — Glycyrrhizin (GL), glycyrrhetinic acid (GA) and side-effects
Glycyrrhizin is mainly absorbed after presystemic hydrolysis to glycyrrhetinic acid (GA; 18-beta-glycyrrhetinic acid (glycyrrhetic acid; the aglycone of glycyrrhizin)). On excretion via the bile it may be reconjugated to glycyrrhetinic acid by commensal bowel flora and then reabsorbed. Glycyrrhizin and glycyrrhetinic acid are associated with the side-effects encountered with high-dose or long-term licorice use, such as elevated blood pressure and fluid retention. In people with prolonged gastrointestinal transit time, glycyrrhetinic acid can accumulate after repeated intake. As GA is 200-1000-fold more powerful an inhibitor of 11 -beta-hydroxysteroid dehydrogenase (11HSD) than glycyrrhizin, this may lead to more significant mineralocorticoid effects. In order to minimise the risk of side-effects, practitioners often use a deglycyrrhizinised form of licorice (DGL).
While G. glabra, G. uralensis and G. inflafa are often seen as similar remedies, there are some differences in the constituents, such as the phenolic contents.