Bioactivity and Potential Health Benefits of Licorice

Some spices and herbs are so precious that, to date, they continue to be used in everyday home remedies. Licorice is one such age-old herb that has been used for its outstanding health benefits. Licorice has been used in Ayurveda and Chinese medicine for centuries as an expectorant. Due to its natural sweetness, it is widely used as a flavouring agent. Studies on Licorice have shown promising results in the treatment of many diseases.

Health Benefits of Licorice

1. Antitussive and Expectorant Activity of Licorice

Due to its anti-inflammatory and antimicrobial properties, licorice root extract aids upper respiratory conditions. It helps treat sore throat, cough, and bronchial catarrh due to antitussive and expectorant effects. These effects are due to glycyrrhizin, which helps to expel congestion in the upper respiratory tract and accelerates tracheal mucus secretion. Studies show that glycyrrhizin also helps to relieve asthma. Similarly, liquiritin apioside, an active compound found in the licorice, has the ability to inhibit capsaicin, a compound that induces cough.

2.Antiulcerative Activity of Licorice

The use of Licorice extract as an anti-ulcerative agent is widely known. It is used to treat gastric and duodenal ulcers due to anti-inflammatory saponins. The primary compound responsible for this activity is glycyrrhizin, which can raise the concentration of prostaglandins in the digestive tract. Prostaglandins stimulate mucous secretion and cell proliferation leading to ulcer healing. Licorice also prolongs the lifespan of stomach surface cells, demonstrating an antipepsin effect. Licorice root extract helps treat peptic ulcers and significantly reduces H. pylori bacteria. Licorice is also employed as an adjuvant for treating spasmodic pains of chronic gastritis. It is often used to relieve symptoms of indigestion and upset stomach. Licorice also alleviates symptoms of gastroesophageal reflux disease (GERD), including acid reflux and heartburn, and is more effective than commonly used antacids.

3. Hepatoprotective Effect of Licorice

Licorice has been employed for over 20 years in Japan to treat chronic hepatitis. The hepatoprotective activity of licorice is due to Glycyrrhizin and glycyrrhetic acid that inhibit free-radical generation and lipid peroxidation. Studies indicate that the root extract of Licorice exhibits significant protection against hepatotoxicity in the liver tissue. The effect of licorice on nonalcoholic fatty liver disease has also been observed. Glycyrrhizin and glycyrrhetinic acids prevent drug-induced liver injury and ensure the disruption of bile acid metabolism. Indeed, glycyrrhetinic acid has been reported as an anti-inflammatory and hepatoprotective compound, whereas Glycyrrhizin significantly reduces serum aminotransferases, improves liver histology, and helps treat chronic hepatitis C. Long-term use of Licorice prevents the development of hepatocellular carcinoma in chronic hepatitis C. Studies have shown that Glycyrrhizin modifies the intracellular transport and suppresses the hepatitis B virus surface antigen. In addition, it prevents the oxidative and hepatic damage caused by aflatoxins, contributing to the anticarcinogenic activity by metabolic deactivation of the hepatotoxin. Licorice significantly reduces the serum enzymes, bilirubin, and proinflammatory cytokines in the liver. Licorice can also be used to treat acute-onset autoimmune hepatitis.

4. Anticancer Effect of Licorice

The licorice root extract protects against cancer due to its antioxidant and anti-inflammatory properties. Licorice inhibits tumour cell growth, with the corresponding reduction in cell number and ascites volume. The root extract of Licorice also exhibits antimutagenic activity by suppressing micronuclei formation and chromosomal aberration in bone marrow cells. Glycyrrhizin and glycyrrhetinic acids are active compounds in treating cancers of the gastric, lung, breast, ovary, cervix, uterus, colorectal, prostate, and skin. They induce apoptosis in cancer cells. licochalcone A found in Licorice inhibits gastric cancer growth by blocking cell cycle progression at the G2/M transition and inducing apoptosis. Licorice also contains Isoliquiritigenin that inhibits cell growth by G2/M cell cycle arrest in breast and prostate tumour cells. Licorice also suppresses liver and pulmonary metastases. Similarly, Glabridin found in Licorice exhibits antitumour effect in various cancer cells, including liver cancer, by inducing apoptosis. Licorice inhibits the proliferation of cancer cells without affecting the normal cells. Licorice also shows anticancer activity in leukaemia by inducing apoptosis of cancer cells by activating intrinsic and extrinsic pathways.

5. Neuroprotective Activity of Licorice

Regular use of Licorice causes a significant improvement in learning and memory. The combination of anti-inflammatory and antioxidant activities of Licorice with neuroprotective effect leads to memory enhancement. Licorice helps in preventing diseases like Alzheimer's. The basis of Alzheimer's is the chronic inflammation of specific brain regions. Licorice contributes to the observed memory-enhancing effects due to its anti-inflammatory property. Also, oxygen-free radicals are implicated in aging and responsible for the development of Alzheimer's disease in elderly persons. The protective role of licorice extract may be attributed to its antioxidant properties, resulting in reduced brain damage and improved neuronal function and memory. The effect is attributed to glabridin found in Licorice, suggesting its potential use in the management of dementia.

6. Oestrogenic and Androgenic Effects of Licorice

The extract of Licorice has antiandrogenic effects in females by increasing the testosterone metabolism, down-regulating androgen receptors, and activating oestrogenic receptors. During menopause, low oestrogen levels lead to uncomfortable symptoms such as hot flashes. Studies show that licorice supplements reduce these symptoms in postmenopausal women. Licorice root contains many compounds, such as liquiritigenin, that activate oestrogen receptors in the body. Licorice root also helps treat polycystic ovary syndrome (PCOS) by reducing ovarian cysts and balancing irregular ovarian follicles. Studies also show that licorice can reduce testosterone production from the adrenal glands in women and help improve the anti-androgen effect of other PCOS treatments like spironolactone while minimizing their side effects.

7. Licorice Role in Skin Diseases

Licorice root extract helps treat various skin diseases due to its antioxidant and anti-inflammatory properties. Licorice protects the skin against oxidative stress and ultraviolet (UV) radiation damage. Licorice is used mainly for skin eruptions, including dermatitis, eczema, pruritus, and cysts. Flavonoids found in Licorice possess depigmenting capabilities and tyrosinase enzyme inhibition effects. The presence of the alpha-keto group in flavonoids is responsible for this activity. Licorice has a preventive effect on pigmentation disorders such as melasma, age spots, and sites of actinic damage. Glabridin found in Licorice inhibits tyrosinase activity, prevents skin inflammation and the formation of melanin in melanocytes, and acts as a skin-lightening agent. The extract of Licorice also promotes hair growth and can be safely used in herbal formulations to treat various types of alopecia. Studies prove that applying a topical gel containing licorice root extract improves eczema.

Conclusion

Licorice has been broadly used as traditional medicine and food industry ingredient, particularly as a flavour and sweetening agent. The roots are used to prevent and treat several diseases, such as cancer, skin problems, and microbial and viral infections. Flavonoids are the most important bioactive compounds responsible for the most biological activities. Different phytochemicals, including glycyrrhizin, glycyrrhetinic acid, glabrin, and isoflavones, are associated with various biological activities, including hepatoprotection, antioxidant, anti-inflammatory, antiviral, antimicrobial, and anticancer activities. These activities generally correlate with traditional knowledge and folk medicine. This review details and explains the traditional use of Licorice and highlights its potential benefits and scope for other industries, such as cosmetic and pharmaceutical ones.