Licorice (Glycyrrhiza glabra), also known as Liquorice, Mulethi, Yashtimadhu, glycyrrhiza, and sweet wood, is one of the most popular medicinal plants of the family Fabaceae (Leguminosae). The genus Glycyrrhiza is derived from the Greek words glykos (sweet) and rhiza (root). Native to Mediterranean areas, Licorice is now common in India, Russia, and China. Licorice extracts are currently used in the pharmaceutical and food industries to manufacture functional foods and food supplements.
History of Licorice
The therapeutic use of Licorice dates back to the Greek and Roman Empires, having a long history of use in traditional medicines and folk remedies. In Chinese herbal medicine also, Licorice figures prominently as a common remedy for gastrointestinal problems, cough, bronchitis, and arthritis. It is used in modern medicines chiefly in cough and cold preparations due to its expectorant activity and as a flavouring agent that masks bitter products like quinine. Traditionally, Licorice is widely used to treat gastritis, peptic ulcers, and respiratory infections. The dried root is used as a tooth cleanser. The most important industrial use of Licorice is the production of food additives, such as flavours and sweetening agents. Licorice is a skin depigmentation agent and is included in topical products in the cosmetic field.Phytochemistry and Bioactive Compounds of Licorice
In the last few years, the chemical constituents of Licorice have been extensively investigated. Nutritionally, Licorice is a source of proteins, polysaccharides, mineral salts, pectins, oestrogens, tannins, phytosterols (sitosterol and stigmasterol), coumarins, glycosides resins, starches, sterols, and gums. Many biological compounds such as triterpenes, saponins, and flavonoids have also been isolated. The main constituent of roots is glycyrrhizin, a triterpenoid saponin that is almost 50 times sweeter than sucrose. Glycyrrhizin is the primary active ingredient and is a mixture of potassium, calcium, magnesium, and glycyrrhizic acid. The yellow colour of Licorice is due to its flavonoid content. The characteristic odour of Licorice is due to volatile components present in the root.Pharmacological Properties
Licorice is one of the oldest and most popular herbal medicines in the world. Many of the historical uses of licorice are still practiced today.1. Antioxidant Activity of Licorice
Licorice has potent antioxidant activity due to its phenolic content. It shows an intense scavenging effect and inhibits microsomal lipid peroxidation due to the presence of licochalcones. The phenolic compounds protect against oxidative stress and inhibit the onset of skin damage. Licorice is useful in dermal and cosmetic products as it counteracts oxidative stress damage and maintains skin stability due to its high antioxidant content.2. Anti-inflammatory Activity of Licorice
Licorice has been used to treat inflammatory diseases since ancient times. The treatment of the upper respiratory tract and gastric diseases with Licorice produces positive effects. Licorice causes a significant decrease in the total cholesterol, triglyceride, and liver enzyme levels. These pharmacological effects are due to an increase in the secretion of serotonin and prostaglandins in the stomach, which lead to a decrease in gastric inflammation. The anti-inflammatory action is primarily mediated by glycyrrhizin, which inhibits factors responsible for inflammation and promotes the healing of stomach and mouth ulcers. The anti-inflammatory effects of glycyrrhizin are similar to those of glucocorticoids and mineralocorticoids. Licorice is also used in renal and liver complications due to its strong anti-inflammatory effects. Glycyrrhizin inhibits liver granuloma formation and inflammatory cytokine production. It also helps to treat endometriosis.3. Antimicrobial Activity of Licorice
Studies show the antimicrobial effect of Licorice, particularly on Gram-positive and Gram-negative bacteria, due to the presence of saponins, alkaloids, and flavonoids. The mechanism behind this is the decrease of bacterial gene expression, the inhibition of bacterial growth, and the reduction of bacterial toxin production. Licorice also shows antibacterial effects against Mycobacterium tuberculosis. The antitubercular property is due to the presence of glabridin. Licorice also helps treat gastric infection caused by Helicobacter pylori due to the presence of glabridin and glabrene. Glabridin also helps Licorice to treat fungal infections.4. Antiviral Activity of Licorice
Licorice extract shows antiviral activity against many viruses due to glycyrrhizin and glycyrrhetinic acid present in it. These compounds have the ability to inhibit virus gene expression and replication, decreasing the adhesion force and stress and reducing High mobility group box 1 (HMGB1) protein binding to DNA. They can also enhance host cell activities by blocking the degradation of enzymes involved in the propagation of the cellular response to inflammation, activating T lymphocyte proliferation, and suppressing host cell apoptosis. The antiviral mechanisms of both compounds are similar, inhibiting the penetration and adsorption of the virus in the early phase of the replicative cycle. Herpes simplex virus (HSV) is one of the most common viral infections. During HSV infection, cellular adhesion is increased, playing a vital role in the inflammatory response. Glycyrrhizin stimulates the defence system against HSV infection. Licorice has a remarkable effect against Kaposi sarcoma-associated herpesvirus (KSHV). Glycyrrhizic acid down-regulates the expression of latency-associated nuclear antigen in B lymphocytes leading to natural cell death (apoptosis) of the KSHV-infected cells. Glycyrrhiza has been used to treat patients with human immunodeficiency virus (HIV). Recently, the antiviral activity of glycyrrhiza against severe acute respiratory syndrome (SARS) virus was evaluated. Glycyrrhizin affects the cellular signaling pathways such as protein kinase C, casein kinase II, and transcription factors. Glycyrrhizin reduces the expression of proinflammatory cytokines affecting coxsackievirus B3-induced myocarditis. Another study shows that glycyrrhizin interferes with highly pathogenic H5N1 influenza virus replication.5. Antidepressant Activity of Licorice
Licorice extract has potential therapeutic value for the treatment of depressive disorders. Recent studies have shown that Licorice extract produces a significant antidepressant effect. It is suggested that the extract interacts with adrenoceptors and dopamine receptors, increasing the levels of norepinephrine and dopamine in the brain.Side Effects and Toxicity of Licorice
High doses of Licorice may cause adverse effects such as hypertension, hypokalaemia, or fluid retention. Excessive consumption of Licorice can produce hypermineralocorticoid-like effects and a consequent tendency to reduce potassium levels (hypokalaemia) and elevate sodium, resulting in oedema. Studies demonstrate that glycyrrhizin is poorly absorbed by the gastrointestinal tract but extensively metabolized by the intestinal microflora to glycyrrhetic acid and monoglucuronyl glycyrrhetic acid both are readily absorbed.Disclaimer:
This content is for information and educational purposes only and should not be perceived as medical advice. Please consult a certified medical or healthcare professional before making any decision regarding your health using the content above.