by Isaiah Pinkerton
Wilkes University,
Wilkes-Barre,
PA
July 2017
Licorice (Glycyrrhiza
glabra) is an herbaceous perennial member of the
legume family (Fabaceae) that is native to Europe and
southern Asia - including India and China (Shibata 2000).
Today, licorice is commonly used in Traditional Chinese
Medicine (TCM) and western mainstream medicine (Kao, et
al. 2014). The benefits currently being researched pertain
to its anti-viral, antibacterial, and anti-cancer
properties, as well as relieving menopausal associated
inflictions. In the past few decades, the need for G.
glabra has increased dramatically and the natural
population of the species has been on the decline due to
overuse in Balochistan region of southwestern Asia, where
it is commercially cultivated (Dastagir & Rizvi
2016).
G. glabra has been used since ancient times in
Greece, Rome, and China. Many prominent botanists at the
time including Theophrastus, Dioscorides, Plinius the
Elder, and Galen recognized the medicinal and agricultural
benefits of the root in particular in extractions,
infusions and potions (Fiore, et al. 2005). Indeed,
recorded in Plini Secundi Naturalis Historiae,
Plinius the Elder recommended the root of the licorice
plant to be used as a remedy for asthma, malaises, ulcers,
kidney stones, skin lesions, and combat sterility, as well
as an antispasmodic, and diuretic (Fiore, et al. 2005).
In modern times, the main component of the licorice root,
glycyrrhizin, is used as a flavoring in tobacco, a
confectionary sweetener in many food products, and a chief
emulsifier in cosmetics (Fenwick 1990).
Licorice has various medicinal attributes that are
associated with numerous bioactive components including
its pure root extract, glabridin, glabrene, ethanol based
extracts, carbenoxolone, glycyrrhizic acid, and ammonium
glycyrrhizate. Animal studies demonstrated that
glycyrrhizin, a saponin, reduced mortality and viral
activity in herpes simplex virus encephalitis and
influenza A virus pneumonia (Flore, et al. 2008). In
vitro studies revealed antiviral activity against
HIV-1, SARS related coronavirus, respiratory syncytial
virus, arboviruses, vaccinia virus and vesicular
stomatitis virus (Flore, et al. 2008, Pu, et al. 2013).
Another chemical component called glabridin, a major
isoflavene, has been associated with a wide range of
biological properties such as antioxidant,
anti-inflammatory, anti-atherogenic, regulation of energy
metabolism, estrogenic, neuroprotective,
anti-osteoporotic, and skin-whitening (Simmler, et al.
2013). Glabridin is reported to posses the capacity to
down-regulate intracellular reactive oxygen species, bind
to antioxidant effectors, and act on estrogen receptors,
potentially as a plant-based Selective Estrogen Receptor
Modulator (Simmler, et al. 2013). In two separate studies,
licorice (G. glabra) chemical derivative glabrene,
another isoflavene, along with glabridin were evaluated
for their efficacy in treating vascular tissue both in
vitro and in vivo for post-menopausal women who have
reported to have a high risk of heart disease. Both
components exhibited activity similar to that of estrogen
in order to modulate vascular injury and prevent
cardiovascular disease by promoting atherogenesis (Somjen,
et al. 2004; Somjen, et al. 2004, Simons, et al. 2011).
A broad spectrum of in vitro and in vivo
studies have recently demonstrated that the mixed extracts
and purified compounds from licorice exhibit anti-cancer
properties by inhibition of proliferation, induction of
cell cycle arrest, apoptosis, autophagy, differentiation,
suppression of metastasis, angiogenesis, and sensitization
of chemotherapy or radiotherapy (Tang, et al. 2015). A
combined treatment of licorice compounds and clinical
chemotherapy drugs remarkably enhances anti-cancer effects
and reduces the side effects of chemotherapeutics (Tang,
et al. 2015). The fatalities attributed to colorectal
cancer have led to numerous studies, including in vitro
evaluation of an ethanol extract of G. glabra
affecting the gene expression of chaperone protein, HSP90.
Observations of cell proliferation and apoptosis had
confirmed the anti-cancer property, and will motivate
extensive in vivo biological evaluation and
subsequently lead to clinical evaluations (Nourazarian, et
al. 2015).
Investigation into possible learning and memory benefits
of licorice on mouse models have been tested. Extracts
were shown to improve memory and enhance learning
potential. Furthermore, licorice extracts reduced
the amnesia effect of diazepam and scopolamine (Dhingra,
et al. 2004; Dhingra, et al. 2004, Chakravarthi, et al.
2013). Screening tests performed against certain strains
of Mycobacterium tuberculosis establish that
glabridin is an effective anti-bacterial agent (Gupta, et
al. 2008). Carbenoxolone, a steroidal derivative of
glycyrrhetenic acid, is an effective treatment against
peptic ulcers, both gastric and duodenal (Pinder, et al.
1976). Additionally, carbenoxolone has the capacity to
prevent and reduce the progression of fatty acid liver
disease in patients with insulin resistance (Rhee, et al.
2012).
The dangers of licorice include moderate chronic or high
acute exposure to glycyrrhizic acid, ammonium
glycyrrhizate, and their metabolites, that causes several
transient systemic alterations. They include
increased potassium excretion, sodium and water retention,
body weight gain, alkalosis, suppression of the
renin-angiotensis-aldosterone system, hypertension, and
muscular paralysis (Cosmetic Ingredient Review 2007). One
account detailed a child with prolonged ingestion of an
excess level of licorice leading to hemorrhagic gastritis
(Wong, et al. 2012).
Glycyrrhiza glabra has been used for thousands of
years for its medicinal and cultural attributes. Likewise,
its active constituents including glycyrrhizin, glabridin,
glabrene, carbenoxolone, glycyrrhizic acid, ammonium
glycyrrhizate, and their metabolites all have proven
medical benefits. The most prominent benefits include
reduction of menopausal associated cardiovascular disease,
relieving hepatic related inflammation,
antibiotic/anti-viral, and anti-cancer properties.
Overdosing on any of its chemical components is rare and
seldom leads to fatality.
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