Articles

Licorice

Plant Part Used

Root

Active Constituents

Triterpene glycosides (including glycyrrhizin, glycyrrhitic acid), polysaccharides, flavonoids (including liquiritin, isoliquiritin, glabrol, apigenin, quercetin) (43),(44),(53), coumarin derivatives, formononetin.(1),(2) [span class=alert]

This section is a list of chemical entities identified in this dietary supplement to possess pharmacological activity. This list does not imply that other, yet unidentified, constituents do not influence the pharmacological activity of this dietary supplement nor does it imply that any one constituent possesses greater influence on the overall pharmacological effect of this dietary supplement.[/span]

Introduction

Glycyrrhiza glabra originates from the Mediterranean and Middle East countries. It has been used medicinally and as a flavoring agent since the 500 B.C. Licorice is used to flavor a wide variety of candies, gum, tobacco products, and beverages. The glycyrrhizin constituent is responsible for sweet taste of licorice which is 50 times sweeter than sugar.(42)

In terms of human well-being, licorice has been used traditionally for many health conditions, including fatigue (in the case of adrenal insufficiency),(3) as an expectorant,(4) in GI distress (particularly of benefit in ulcers),(5),(6),(7) diabetes, hypertension, obesity, cough, asthma, and inflammatory conditions.(8),(9),(41),(42),(43) The Chinese traditionally have also used Glycyrrhiza uralensis as a medicinal agent.

Interactions and Depletions

Interactions
Depletions

Dosage Info

Dosage Range

250-500mg (standardized extract), 3 times a day
-OR-
15-30 drops of a liquid extract (1:4w/v), 3 times a day in favorite beverage.

DGL licorice: 250-500mg, 3 times a day; products should be chewed for optimal results.

Tea: One cup of hot water over one teaspoonful of herb after each meal. (10)

Most Common Dosage

250mg (standardized extract), 3 times a day
-OR-
15-30 drops of a liquid extract (1:4w/v), 3 times a day in favorite beverage.

DGL licorice: 250mg, 3 times a day; products should be chewed for optimal results.

Tea: One cup of hot water over one teaspoonful of herb after each meal.

Standardization

[span class=doc]Standardization represents the complete body of information and controls that serve to enhance the batch to batch consistency of a botanical product, including but not limited to the presence of a marker compound at a defined level or within a defined range.[/span]

The most current available medical and scientific literature indicates that this dietary supplement should be standardized to 12-20% glycyrrhizin per dose (also known as glycyrrhizic or glycyrrhizinic acid); DGL (deglycyrrhizinated licorice) standardized to no greater than 1-2% glycyrrhizin per dose. Licorice supplements can be purchased in two forms. Regular licorice products with a glycyrrhizin (also known as glycyrrhizic or glycyrrhizinic acid)content usually of 12-20%, and then deglycyrrhizinated licorice (DGL), with a glycyrrhizin content usually not greater than 1-2%. The DGL product is recommended for peptic ulcer disease (chewable only) and those individuals susceptible to cardiovascular diseases such as hypertension. The products with a higher glycyrrhizin content are used as expectorants and for adrenal stress.

Uses

Frequently Reported Uses

  • Expectorant In Coughs, Bronchial Complaints
  • Ulcers (DGL)
  • Hepatoprotective
  • Bacterial Infections
  • Adrenal Support
Other Reported Uses
  • Viral Infections
  • Inflammation
  • Antioxidat
  • Antigenotoxic/Antimutagenic

Toxicities & Precautions

Health Conditions

Based on pharmacology and animal studies, licorice should be used with caution in individuals with hypertension, (11) kidney, (12) or liver problems. (13)

Side Effects

Based on animal data and pharmacology, if a non-DGL form is taken, there is a risk of pseudohyperaldosteronism leading to increased blood pressure, potassium loss, weakness and edema.(14),(15),(16) It is safest to use a deglycyrrhizinated (DGL) form in peptic ulcer to avoid this potential effect. (17)

Pregnancy/ Breast Feeding

If pregnant or nursing, consult a physician before use.

Age Limitations

Do not use in children under 2 years of age unless recommended by a physician.

Pharmacology

Licorice root is reported to have a variety of pharmacologic activities. Licorice root has phytoestrogenic activity due to its isoflavone content (formononetin). (18) Because of the weak affinity for binding to estrogen receptors, estrogenic side effects are not seen. Licorice root has an interesting effect on cortisol. It reportedly counteracts the effects of cortisol by inhibiting adrenal and thymus atrophy, as well as by reducing cholesterol manufacturing. (19) Licorice root is claimed to inhibit antibody formation and support the stress response and the inflammatory response. (20) Licorice root reportedly inhibits inflammatory prostaglandin formation and leukotrienes by inhibiting the enzymes responsible for their metabolic activation and manufacture. (21) Another more recent addition to the possible mechanism of the constituent glycyrrhizin’s anti-inflammatory activity is due in part to its anti-thrombin action. (22)

Licorice root is reported to have antioxidant effects, which can be linked to its hepatoprotective capabilities. (23),(24),(25) Flavonoids from licorice have been reported to provide protection to hepatocytes exposed to carbon tetrachloride, and galactosamine. (26) The research suggests that the anti-lipid peroxidation effect of licorice is the central mechanism contributing to its protective action against carbon tetrachloride-induced hepatotoxicity. (27) Further results suggest that glycyrrhiza may inhibit the NF-kappaB binding activity in carbon tetrachloride and ethanol-induced chronic liver injury. (28) Also, glycyrrhiza may be used in commercial topical skin preparations against damage caused by free radical and reactive oxygen species (ROS). (46)

Evidence from human and animal laboratory studies have demonstrated that the constituent isoliquatirin apioside found in licorice has antigenotoxic activity. This constituent has been reported to destroy ROS that initiate carcinogenesis and mutagenesis through oxidative DNA damage. The compound isoliquaritin apioside has also been reported to exert a protective effect against H2N2 and 4-nitroquinoline-N-oxide induced damage of DNA in Escherichia coli strains and in human blood lymphocytes. (47)

Licorice also has mucolytic activity and is used as an expectorant. The component glycyrrhizin produces demulcent and expectorant effects by stimulation of tracheal mucous secretion, although the potential for side effects are increased. (29) Licorice roots also contain polysaccharides which have been reported to be immunostimulating (increases macrophoges in vitro). (30) Licorice may also stimulate interferon production in the body, which could support its antiviral activity. (31),(32) Reported in an in vitro study, the glycyrrhizin in licorice is reported to inactivate herpes simplex virus particles irreversibly.(33) Flavonoids found in licorice root have been reported to have antimicrobial activity. (34)

Licorice root has been reported to have antimicrobial and antiviral activity. A laboratory study found that a component of licorice called glabridin is effective against Mycobacterium tuberculosis.(51) Clinical trials have investigated glycyrrhizin’s activity in chronic viral hepatitis and human immunodeficiency virus (HIV) infections. Glycyrrhizin has also been reported to prevent the development of hepatic carcinoma from hepatitis C and have in vitro antiviral activity against severe acute respiratory syndrome (SARS) associated corona virus.(45),(49)

Deglycyrrhizinated (DGL) licorice has demulcent activity, having the ability to protect irritated mucous membranes. (35) In cases where the intestinal lining is inflamed, DGL licorice reportedly stimulates the production of mucus, and is used to reduce symptoms. (36) Most studies on the stomach ulcer have focused mainly on polysaccharides constituent which act as anti-adhesive against the bacterial docking process of Helicobacter pylori to human stomach tissue. This bacterium is one of the main causes of chronic infection to the stomach ulcer. (44)

When compared with cimetidine in several clinical studies, a proprietary DGL licorice product performed as effectively as the pharmaceutical counterpart. (37) , (38) Another study reported in a double blind, placebo controlled crossover study that when DGL licorice was combined with aspirin, there was less blood loss in patients receiving the combination versus aspirin alone. (39)

The combination of licorice with other Korean native herbs including Lonicera japonica, Cassia obtusifolia L.,Adenophora triphylla var. japonica and Rhynchosia nulubilis has been reported to inhibit xanthine oxidase (XO) activity. Inhibition of XO can block the synthesis of uric acid, leading to the ability to treat gout and hyperuricemia. (40)

The polysaccharides of glycyrrhiza plants have been reported to have immune modulating activity in  laboratory animals. Laboratory studies have also reported that a high-fat diet decreased the proliferation index of spleen lymphocytes and the level of serum LgA, LgG and LgM in mice, therefore modulating immunostimulatory activity. When extract of polysaccharides were injected into mice, the level of immunostimulatory activity was increased by enhancing the level of serum LgA, LgG and LgM in mice. (48) Another study has reported the polysaccharide fraction has many functions including anti-viral and anti-tumor with a low cellular toxicity. (50)

Of note, licorice has been reported to have antidepressant activity in animal studies, possibly through the inhibition of monoamine oxidase by glycyrrhizin, which will increase the levels of monoamine such as epinephrine and dopamine in brain and subsequently lead to production of antidepressant effects. The results reported that licorice extract significantly reduced the immobility time of mice without any significant effect on its locomotor activity.(52)

References

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