General Introduction
Liquorice (Glycyrrhiza glabra), also spelled as “Licorice,” is a perennial herb that belongs to the Fabaceae family. The plant is native to Southern Europe, the Middle East, and parts of Asia, including India and China. The name “liquorice” is derived from the Greek words “glukos” (sweet) and “riza” (root), reflecting the plant’s sweet-tasting roots, which have been valued for their medicinal properties for thousands of years.
Liquorice root has been used in traditional medicine systems such as Ayurveda, Traditional Chinese Medicine (TCM), and Unani for its diverse therapeutic effects, including its role as an anti-inflammatory, antiulcer, antiviral, and expectorant agent. Beyond its medicinal uses, liquorice is widely used as a flavoring agent in food, beverages, and confectionery products.
Composition and Chemistry
Liquorice root contains a wide range of bioactive compounds, including:
1. Triterpenoid Saponins:
– Glycyrrhizin (Glycyrrhizic Acid): The principal bioactive component, glycyrrhizin, is a triterpenoid saponin responsible for the characteristic sweet taste of liquorice. Glycyrrhizin is about 50 times sweeter than sucrose and has potent anti-inflammatory, antiviral, and hepatoprotective properties.
– Glycyrrhetinic Acid: A metabolite of glycyrrhizin, glycyrrhetinic acid is known for its anti-inflammatory, antioxidant, and antitumor properties.
2. Flavonoids:
– Liquorice contains several flavonoids, such as liquiritin, isoliquiritin, liquiritigenin, and glabridin, which contribute to its antioxidant, anti-inflammatory, and antimicrobial activities.
– Isoflavonoids: Formononetin and glabrol are examples of isoflavonoids found in liquorice, known for their estrogenic activity and antioxidant properties.
3. Polysaccharides:
– Polysaccharides in liquorice, such as arabinogalactans, have immunomodulatory and anti-inflammatory effects.
4. Coumarins:
– Liquorice contains coumarins like herniarin and umbelliferone, which possess anticoagulant, antimicrobial, and antioxidant properties.
5. Essential Oils:
– Essential oils in liquorice root include compounds like eugenol, which have antimicrobial and anti-inflammatory properties.
6. Other Compounds:
– Liquorice also contains sterols, tannins, asparagine, and amino acids, which further contribute to its medicinal properties.
Chemistry and Chemical Classes
Liquorice comprises several chemical classes:
1. Triterpenoid Saponins:
– These are glycosides consisting of a sapogenin (aglycone) linked to a sugar chain. Glycyrrhizin is a prime example, which undergoes hydrolysis to form glycyrrhetinic acid.
2. Flavonoids:
– Polyphenolic compounds known for their antioxidant properties, which help neutralize free radicals and reduce inflammation.
3. Isoflavonoids:
– A class of flavonoids with estrogenic activity, contributing to liquorice’s potential role in hormone-related conditions.
4. Coumarins:
– Aromatic compounds with anticoagulant and anti-inflammatory properties.
5. Polysaccharides:
– Carbohydrate polymers that have immunostimulatory and anti-inflammatory effects.
Bio-Sources
Liquorice is obtained primarily from the roots and rhizomes of Glycyrrhiza glabra and other species such as Glycyrrhiza uralensis (Chinese liquorice) and Glycyrrhiza inflata:
– Geographical Distribution: Native to regions in Europe, the Mediterranean, parts of Central Asia, and the Middle East. It is cultivated extensively in countries like Spain, Turkey, Iran, China, and India.
– Parts Used: The root and rhizome are primarily used for their medicinal properties and as flavoring agents.
Therapeutic Uses of Liquorice
Liquorice has a wide range of therapeutic uses, attributed to its diverse bioactive compounds:
1. Anti-Inflammatory:
– Glycyrrhizin and glycyrrhetinic acid exert strong anti-inflammatory effects by inhibiting the production of inflammatory cytokines and enzymes such as cyclooxygenase-2 (COX-2). Liquorice is used in treating conditions like arthritis, gastritis, and inflammatory skin conditions.
2. Antiviral:
– Glycyrrhizin has demonstrated antiviral activity against various viruses, including hepatitis C virus (HCV), human immunodeficiency virus (HIV), herpes simplex virus (HSV), and SARS-CoV-2. It inhibits virus replication and boosts the immune response.
3. Gastroprotective and Antiulcer:
– Liquorice is traditionally used to treat gastrointestinal disorders like peptic ulcers, gastritis, and dyspepsia. The flavonoids and saponins in liquorice help protect the gastric mucosa, enhance mucosal blood flow, and reduce gastric acid secretion.
4. Hepatoprotective:
– Glycyrrhizin has been found to have hepatoprotective effects, protecting liver cells from damage due to toxins, viruses, and inflammation. It is used in treating chronic hepatitis, liver cirrhosis, and non-alcoholic fatty liver disease (NAFLD).
5. Antioxidant:
– Flavonoids and other phenolic compounds in liquorice exhibit antioxidant properties, which help neutralize free radicals, reduce oxidative stress, and protect against cellular damage.
6. Expectorant and Respiratory Uses:
– Liquorice is used as an expectorant to help loosen mucus in the airways, making it easier to cough up. It is commonly found in herbal formulations for treating coughs, bronchitis, and sore throats.
7. Hormonal and Menopausal Support:
– Isoflavonoids in liquorice exhibit estrogenic activity, which may help alleviate symptoms of menopause, such as hot flashes and mood swings.
8. Antimicrobial:
– Liquorice exhibits antibacterial, antifungal, and antiviral properties, making it useful for treating infections of various kinds.
9. Anti-Cancer:
– Some studies suggest that components in liquorice, such as glycyrrhetinic acid and flavonoids, may have antitumor properties, inhibiting the growth and proliferation of certain cancer cells.
Commercial Applications
1. Pharmaceutical Industry:
– Liquorice extracts are used in a variety of pharmaceutical preparations for their anti-inflammatory, antiviral, gastroprotective, and expectorant properties. Glycyrrhizin is a key component in formulations for treating liver disorders and chronic hepatitis.
2. Herbal Medicine:
– Liquorice is a common ingredient in herbal supplements and traditional medicines, used for a wide range of indications, from respiratory ailments to digestive disorders.
3. Food and Beverage Industry:
– Liquorice is widely used as a flavoring agent in confectionery, candies, soft drinks, chewing gums, and alcoholic beverages like liqueurs and certain beers. The sweet-tasting compound glycyrrhizin is a natural alternative to sugar in many low-calorie products.
4. Cosmetics:
– Liquorice extracts are used in skin care products for their anti-inflammatory, antioxidant, and depigmenting effects. It is a common ingredient in creams and lotions aimed at treating hyperpigmentation, redness, and other skin disorders.
5. Agriculture:
– Due to its antimicrobial properties, liquorice extracts are used in natural pesticides and plant growth-promoting agents.
6. Veterinary Medicine:
– Liquorice is used in formulations for treating various animal conditions, particularly for its anti-inflammatory and soothing properties.
Conclusion
Liquorice is a versatile plant with a rich composition of bioactive compounds that contribute to its wide range of therapeutic and commercial applications. From its role in traditional medicine to its use in modern pharmaceuticals, food, cosmetics, and agriculture, liquorice continues to be a valuable resource across multiple industries. However, it is important to use liquorice with caution, particularly due to its potential side effects, such as hypertension and electrolyte imbalance, associated with prolonged use or high doses of glycyrrhizin.
