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Glycyrrhiza glabra is one of the most biologically active herbs known. Its use dates back several thousand years in both Western and Eastern cultures. It has found extensive therapeutic use throughout the world and has been the subject of an enormous amount of research.

Triterpenoid Saponins

The main one is glycyrrhizin; a mixture of calcium and potassium salts of glycyrrhizinic acid[1]. Glycyrrhizin is extremely sweet (50 times sweeter than sugar, but is safe for diabetics) and foams in water[1,2]. Published analytical data on the amount of glycyrrhizin in licorice vary considerably. This is due partly to different analytical methods and partly to actual variations in the percentages present in different commercial varieties and samples. 6-13% is the usual range[1].  The intestinal flora of the large bowel cleaves Glycyrrhizin to its aglycone portion glycyrrhetinic acid (GA) and a disaccharide. It is GA and Glycyrrhizin which account for much of the activity of Glycyrrhiza[5].  GA is not well absorbed from the GIT, which explains the need for relatively large doses of Glycyrrhiza to demonstrate pharmacological activity[2].

Others saponins in Glycyrrhiza include, liquirtic acid, glycyrrhetol, glabrolide, isoglabrolide, licoric acid, phytosterols[3].

Flavonoids & Isoflavonoids

The flavonoids in Glycyrrhiza are responsible for its yellow colouring. They include liquirtin (main flavonoid), isoliquiritin, liquirtigenin, rhamnoliquirtin, neoliquirtin, licoflavonol, licoisoflavones A & B, licoisoflavone, formononetin glabrol, glabrone, glysarin [1,3], glabridin, glabrene, 3-hydroxyglabrol, 4’-O-methylglabridin, 3’-methoxyglabridin, formononetin, phaseollinisoflavan, hispglabridin A, hispglabridin B[4].

Polysaccharides

Mainly glucans [3]

Coumarins

Liqoumarin, umbelliferone, herniarin [2,3]

Sterols

Beta-sitosterol, stigmasterol, dihydrostigmasterol [5]

Phytoestrogens

Glizestrone

Volatile oils

Fenchone, linalool, benzaldehyde [3]

Bitter principles

Glycyramarin [1]

Nutritional Constituents

• Vitamins: E, B1, B2, B3, B5 [5], B6, inositol, biotin
• Minerals: Phosphorus, manganese, iodine, chromium, zinc [5]
• Other: lecithin, starch (2-20%), sucrose, glucose, lignans, amino acids: Asparagine (1-2%) [1], gums [3]

Antiallergenic

Glycyrrhizin is reported to exhibit some antiallergenic activity [5]. Scientific studies where Glycyrrhizin was administered to animals have shown to inhibit experimentally induced allergenic reactions [7]. However, no such activity has been proven in scientific studies on humans to date [5].

Antibacterial

Alcohol extracts of Glycyrrhiza have displayed antimicrobial activity invitro against Staphylococcus aureus, Streptococcus mutans, Mycobacterium smegmatis and Candida albicans strains of bacterium [8]. The majority of antimicrobial effects are due to isoflavonoid components (particularly hispaglabridin & B, 4’-O-methylglabridin, glabridin, glabriol and 3-hydroxyglabrol) [4,7].

A trial conducted in Japan demonstrated Glycyrrhiza root to be effective against an original staphylococcus aureus strain that had already been made resistant to penicillin and streptomicin, as well as against succeeding drug resistant cultures or generations of that strain (which were continuing to develop ever greater resistance to the standard drugs) [8].

Anti-inflammatory

GA and its derivatives exert an antiinflammatory action [5]. Although significant research has been conducted to understand the mechanism responsible for this action, it is still not well understood [2]. Many researchers believe it is due to the steroid-like structure of GA, (see Figure 1 above) which produces a cortisol-like-effect that inhibits inflammation [9].

The flavonoid liquirtin also exhibits an antiinflammatory activity [5].

Antipyretic

Glycyrrhiza has historically been used for fever management. GA and its derivatives are thought to be responsible for the antipyretic action of Glycyrrhiza [5,8].

Antispasmodic

The flavonoid components of Glycyrrhiza root exhibit antispasmodic action [1].

Antiviral

Glycyrrhizin and GA exhibit significant antiviral activity. Research conducted has revealed several different mechanisms may be responsible for these antiviral effects, including:

• Activation of interferon activity [5,7,8]. Glycyrrhizin and GA induce interferon – the body’s natural antiviral compound [7]. This produces significant antiviral activity, because interferon binds to cell surfaces, stimulating synthesis of intracellular proteins that block viral DNA [7,11].
• Intracellular destruction of virus particles [8]
• Prevention of intracellular ‘uncoating’ or activation, of infecting viruses [8]
• Impairment of the assembling ability of virus structural components [8]

Immunomodulatory

Research on the polysaccharides in Glycyrrhiza have shown they are capable of stimulating the immune system by:

• Increasing the phagocytic activity of macrophages [10]
• Stimulating macrophages to secrete Interleukin-1 (IL-1) [10]
• Enhancing both natural killer (NK) cell and antibody-dependant cellular cytotoxicity (ADCC) activities [10]

GA is also believed to exhibit some important immunomodulating effects including:

• Activation of macrophages [7].
• Enhancement NK cell activity [7].
• Glycyrrhizin was shown to protect mice exposed to lethal doses of influenza virus through the stimulation of IFN-gamma production by T cells [11].

• Potent inhibition of classical complement pathway (IC50). This anticomplementary activity of beta-glycyrrhetinic acid appears to be dependent on its configuration, since the alpha form was not active [12].
• Inhibition of antibody formation [12].

Expectorant

• Glycyrrhiza exhibits expectorant action. This action is produced due to a reflex expectorant action from the gastrointestinal tract mediated by the embryonic neural link between the mucous membranes of the GIT and the respiratory tract [13]. Glycyrrhizin exerts a local effect in the GIT upon ingestion. This effect can best be described as a slight irritation of the mucous membranes, which stimulates the secretion of mucous from the respiratory tract mucous membranes. This helps to loosen tenacious sputum and promote its removal from the respiratory tract [3].
• Glycyrrhiza also has a demulcent action which is soothing to irritated mucous membranes [5].
• GA and its derivatives have an anti-tussive effect similar to codeine [2].

• Bronchitis (acute & chronic) [2,5,3]
• Coughs (acute & chronic) [2,14]
• Bronchial catarrh [3]
• Irritation of respiratory mucosa [8]
• Asthma [2,5]
• Pharyngitis
• Dyspnoea [2,5]

The anti-viral, anti-bacterial, antipyretic and immunomodulating actions of Glycyrrhiza make it a useful treatment for cold, fevers and influenza. [2,3,5,7] Historically Glycyrrhiza has been used to treat common cold symptoms [7].

The antiinflammatory action of glycyrrhiza assists the body to deal with the inflammation that often accompanies infections of the respiratory tract both acute and chronic [8]

1. Evans, W. C., Pharmacognosy, (13^th ed), Baillaire Tindall, UK, 1989
2. Mediherb Newsletter April 1989, Licorice- The Universal Herb, Publishing Details Unavailable
3. Hoffmann, D, The Herbalist CD Rom, version 2, Hopkins Technology, UK, 1996
4. Mitscher, L. A., et.al, Antimicrobial Agents from Higher Plants. Antimicrobial isoflavonoids and Related Substances from Glycyrrhiza glabra. J Nat Prod 1980 Mar-Apr;43(2):259-69
5. Fisher, et.al, Materia Medica of Western Herbs for the Southern Hemisphere, Revised Ed, no publishing details available, 1996
6. Kuroyanagi, T, et.al, Effect of Prednisone and Glycyrrhizin on Passive Transfer of Experimental Allergic Encephalomyelitis, Allergy, 15: 67-75, 1966
7. Murray, M. T., The Healing Power of Herbs, Prima Publishing, USA, 1995
8. Mowrey, D, The Scientific Validation of Herbal Medicine, Keats Publishing, USA, 1986
9. Cyong, J, A Pharmacological Study of the Antiinflammatory Activity of Chinese Herbs. A Review, Acupunct Elector-Ther, 7: 173-202, 1982
10. Yang, G, et.al, Immunopotentiating Effect of Traditional Chinese Drugs – Gensenoside & Glycyrrhiza Polysaccharide. Proc Clin Acad Med Sci Peking Union Med Coll, 1990;5 (4):188-93
11. Utsunomiya, T, et.al, Glycyrrhizin, an Active Component of Licorice Roots, Reduces Morbidity and Mortality of Mice Infected with Lethal Doses of Influenza Virus
12. Kroes, B. H., Inhibition of Human Complement by Beta-glycyrrhetinic Acid. Immunology, 1997 Jan;90(1):115-20
13. Wohmulth, H, Pharmacognosy and Medicinal Plant Pharmacology: A Student Manual, 1998
14. Anderson, D. M., et.al, The antitussive activity of GA and its derivatives. Journal of Pharmacy and Pharmacology, 13:396-404, 1961