Liquorice Root Extract

Glycyrrhiza glabra, commonly known as liquorice, is a medicinal herb with long, cylindrical, and branched roots with runners. The dried runners and roots are the parts used as medicines.1

Glycyrrhiza glabra’s natural habitat is Southwest and Central Asia as well as Europe.2

The medicinal use of liquorice dates back several thousand years. Its traditional uses include treating peptic ulcers, asthma, pharyngitis, malaria, abdominal pain, insomnia, and infections.1

The major active component of liquorice root is the triterpenoid saponin glycyrrhizin, which is also known as glycyrrhizic acid or glycyrrhizinic acid. Other active constituents include isoflavonoids (e.g., isoflavonol, glabrol), chalcones, coumarins, sterols, and lignins.1,3

Research shows that liquorice roots have antiviral and antibacterial abilities. Its antiviral properties prevent virus replication, while its antibacterial properties inhibit bacterial function. Liquorice also exhibits antifungal activity.4-7

Antiviral and
Immunostimulatory
Effects

Drug resistance and side effects of the currently used drugs in Herpes Simplex Virus 1 (HSV-1) infections have drawn researchers’ attention to herbal plants such as liquorice.8

Studies demonstrate that topical glycyrrhetinic acid and derivatives help reduce the healing time and pain associated with cold sores and genital herpes. Research also suggests that liquorice strengthens the immune system and may even fight off the herpes virus, the virus that causes cold sores. The antiherpetic activity of liquorice root extract may be due to a number of mechanisms such as inhibition of the herpes virus attachment process through direct contact between the virus and the extract.9,10

Glycyrrhizin inactivates HSV-1 irreversibly and stimulates the synthesis and release of interferon. Administration of glycyrrhizin to mice with herpetic encephalitis increased their survival rate on average about 2.5 times, whereas it reduced HSV-1 replication in the brain to 45.6% of the controls. Glycyrrhizin also inhibited the thymolytic and immunosuppressive action of cortisone. Other liquorice components exerted immunomodulatory effects as well.11

Glycyrrhiza has significant anti-inflammatory and antiallergic activity. Much of glycyrrhiza’s anti-inflammatory activity is due to its cortisol-like effects.12,13

Another important use of glycyrrhizic acid is in the inflammatory skin diseases atopic dermatitis. Glycyrrhizic acid inhibited the release of the cytokines interleukins in a mice model of atopic dermatitis. By inhibiting the inflammatory factor HMGB1 (High-Mobility Group protein B1), glycyrrhizic acid improves the symptoms of atopic dermatitis. Glycyrrhizic acid sequesters HMGB1 and regulates the production of inflammatory cytokines, which, in turn, prevents contact dermatitis.14,15

Glycyrrhetinic acid exerts an effect similar to that of topical hydrocortisone in the treatment of eczema, contact and allergic dermatitis, and psoriasis. In many studies, glycyrrhetinic acid was found to be superior to topical cortisone, especially in chronic cases.16,17

Skin disorders such as age spots, melasma, and sites of actinic damage can develop due to the accumulation of melanin. Glabrene and isoliquiritigenin, found in glycyrrhiza, can inhibit tyrosinase, a key enzyme in melanin biosynthesis.18

The antibacterial effects of glycyrrhiza are due to its isoflavonoid components. Glycyrrhiza displayed antimicrobial activity in vitro against Helicobacter pylori, Staphylococcus aureus (including antibiotic-resistant strains), Streptococcus mutans, Mycobacterium smegmatis, Bacillus subtilis, S. pyogenes, Haemophilus influenzae, Moraxella catarrhalis, and Candida albicans.19,20

  1. Murray MT. Glycyrrhiza glabra(Licorice). Textbook of Natural Medicine. 2020;641-647.e3.
  2. Sabouri Ghannad M, Mohammadi A, Safiallahy S, et al. The Effect of Aqueous Extract of Glycyrrhiza glabra on Herpes Simplex Virus 1. Jundishapur J Microbiol. 2014;7(7):e11616.
  3. Hattori M, Sakamoto T, Kobashi K. Metabolism of glycyrrhizin by human intestinal flora. Planta Med. 1983;48:38–42. 
  4. Wang L, Yang R, Yuan B, et al. The antiviral and antimicrobial activities of licorice, a widely-used Chinese herb. Acta Pharm Sin B. 2015;5(4):310-315.
  5. Huang W, Chen X, Li Q, et al. Inhibition of intercellular adhesion in herpex simplex virus infection by glycyrrhizin. Cell Biochem Biophys. 2012;62(1):137-140. 
  6. Ahn SJ, Cho EJ, Kim HJ, et al. The antimicrobial effects of deglycyrrhizinated licorice root extract on Streptococcus mutans UA159 in both planktonic and biofilm cultures. Anaerobe. 2012;18(6):590-596.
  7. Treutwein J, Cergel S, Runte J, et al. Efficacy of Glycyrrhiza glabraextract fractions against phytopathogenic fungi. Julius-Kühn-Archiv. 2010;428:82.
  8. Sabouri Ghannad M, Mohammadi A, Safiallahy S, et al. The Effect of Aqueous Extract of Glycyrrhiza glabra on Herpes Simplex Virus 1. Jundishapur J Microbiol. 2014;7(7):e11616.
  9. Partridge M, Poswillo D. Topical carbenoxolone sodium in the management of herpes simplex infection. Br J Oral Maxillofac Surg. 1984;22:138–145.
  10. Csonka G.W, Tyrrell D.A. Treatment of herpes genitalis with carbenoxolone and cicloxolone creams. A double blind placebo controlled trial. Br J Vener Dis. 1984;60:178–181.
  11. Sekizawa T, Yanagi K, Itoyama Y. Glycyrrhizin increases survival of mice with herpes simplex encephalitis. Acta Virol.2001;45:51–54.
  12. Kuroyanagi T, Saito M. Effect of prednisolone and glycyrrhizin on passive transfer of experimental allergic encephalomyelitis. 1966;15:67–74. 
  13. Cyong J, Otsuka Y. A pharmacological study of the anti-inflammatory activity of Chinese herbs. A review. Acupunct Electrother Res. 1982;7:173–202. 
  14. Lee S.H, Bae I.H, Choi H, et al. Ameliorating effect of dipotassium glycyrrhizinate on an IL-4- and IL-13-induced atopic dermatitis-like skin-equivalent model. Archives of Dermatology Research. 2019;311:131–140. 
  15. Wang Y, Zhang Y, Peng G, et al. Glycyrrhizin ameliorates atopic dermatitis-like symptoms through inhibition of HMGB1. International Immunopharmacology. 2018;60:9–17.
  16. Nokhodchi A, Nazemiyeh H, Ghafourian T. The effect of glycyrrhizin on the release rate and skin penetration of diclofenac sodium from topical formulations. Farmaco. 2002;57:883–888. 
  17. Saeedi M, Morteza-Semnani K, Ghoreishi M.R. The treatment of atopic dermatitis with licorice gel. J Dermatolog Treat. 2003;14:153–157. 
  18. Nerya O, Vaya J, Musa R. Glabrene and isoliquiritigenin as tyrosinase inhibitors from licorice roots. J Agric Food Chem. 2003;51:1201–1207.
  19. Mitscher L, Park Y, Clark D. Antimicrobial agents from higher plants. Antimicrobial isoflavonoids and related substances from Glycyrrhiza glabra L. var. typica. J Nat Products.1980;43:259–269. 
  20. Fukai T, Marumo A, Kaitou K. Antimicrobial activity of licorice flavonoids against methicillin-resistant Staphylococcus aureus. Fitoterapia. 2002;73:536–539. 

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