Glycyrrhiza glabra, the liquorice plant, is a flowering perennial from the Fabaceae family of legumes. Native to the Mediterranean, India and parts of East Asia, this plant is harvested in the autumn with pale purple-white flowers in an infloresence and can grow to nearly 2 metres tall. When planted in fields, these plants ameliorate high saline soils to yield higher wheat and cotton harvests.
These plants are not suited for ornamental potting as the roots branch extensively, growing in the horizontal direction producing fibrous wood. These roots are the structures producing sweet extracts used in medicine flavouring and confectionary.The sweet root extract is called succuss liquiritiae in pharmacological terms (Fenwick et al. 1990) with the major component being glycyrrhizin. In the US, there is an average consumption of 0.027-3.6 mg of glycyrrhizin per kilogram per day from food, tobacco and medicine.
Biochemical studies suggest there are both toxic and beneficial properties of consuming liquorice extracts. The consumption of liquorice may interfere with cortisol inactivation leading to a build-up of excess cortisol levels in the body. On the other hand, glycyrrhizin is neither a teratogenic nor mutagenic agent and consumption show anti-ulcer, anti-viral and hepatoprotective properties. The acceptable daily intake is proposed between 0.015-0.229 mg per kilogram of body weight per day which is a fraction of the average amount being consumed in the US (Isbrucker and Burdock, 2006).
Flavonoids, a metabolite of plants, were isolated from G. glabra and two other types of liquorice species to test for antimicrobial activity against methicillin sensitive Staphylococcus aureus, methicillin resistant S. aureus, Micrococcus luteus, Bacillussubtilis, E. coli, Klebsiella pneumoniae and Pseudomonas aeruginosa (Fukai et al, 2002). These liquorice extracts proved to be effective against certain types of bacteria.
It is interesting to note that, Liquorice, the candy, often does not contain any amount of root extract. Rather the name refers to the soft chewy texture of this type of confection that is comprised of ingredients that prevent the final product from hardening. The major ingredients of the candy are flour, cane sugar and corn syrup with added artificial flavouring. The process of producing liquorice type candy is patented by the inventors Rest and Smylie (1974).
Fenwick, G. R., Lutomski, J., & Nieman, C. (1990). Liquorice, Glycyrrhiza glabra L.—Composition, uses and analysis. Food Chemistry. 38; 119-143.
Fukai, T., Marumo, A., Kaitou, K., Kanda, T., Terada, S., & Nomura, T. (2002). Antimicrobial activity of licorice flavonoids against methicillin-resistant Staphylococcus aureus. Fitoterapia, 73(6), 536-539.
Isbrucker, R. A., & Burdock, G. A. (2006). Risk and safety assessment on the consumption of Licorice root (Glycyrrhiza sp.), its extract and powder as a food ingredient, with emphasis on the pharmacology and toxicology of glycyrrhizin. Regulatory Toxicology and Pharmacology. 46; 167-192.
Rest, D., & Smylie, C. (1974). U.S. Patent No. 3,806,617. Washington, DC: U.S. Patent and Trademark Office.