Glycyrrhiza glabra Linn, a commonly used herb in ayurvedic medicine. Although some of the review articles on this plant have already been published, the present article contains all the updated information on its phytochemical and pharmacological activities performed by widely different methods. Studies indicate that Glycyrrhiza glabra Linn possesses antibacterial, antioxidant, antimalarial, antispasmodic, anti-inflammatory and anti hyper glycemic properties. Various other effects like antiulcer, antiviral, antihapatotoxic, antifungal and herpes simplex have also been studied. The results are encouraging and indicate that this herb should be studied more extensively to confirm these results and reveal other potential therapeutic effects.
Key words: - Glycyrrhiza glabra Linn, shrub, expectorant, anti-tussive, laxative and sweetener.
Glycyrrhiza glabra Linn is one of the most widely used herb from the ancient medical history of Ayurveda, both as a medicine and also as a flavouring herb. It is a sweet, moist, soothing herb that detoxifies and protects the liver and is also a powerful anti-inflammatory, being used in conditions as varied as arthritis and mouth ulcers.
Glycyrrhiza glabra Linn is commonly known as Yashti-madhuh. Madhuka (Sanskrit) Jashtimadhu, Jaishbomodhu (Bengali) Jethimadhu (Gujarat) Jothi-madh, Mulhatti (Hindi) Yastimadhuka, atimaddhura (Kannada) Iratimadhuram (Malayalam) Jeshtamadha (Marathi) Jatimadhu (Oriya) Atimaduram (Tamil) Atimadhuranu, Yashtimadhukam (Telugu) Licorice, Liquorice, Sweet wood (English). Dried roots and stolons, peeled or unpeeled of Glycyrrhiza glabra are used.
The Liquorice of medicine and commerce is derived from the sweet root of various species of Glycyrrhiza, a genus which contains about fourteen species, natives of warmer temperate countries in both the New and Old Worlds, ten of them having roots more or less sweet, but most of them not sufficiently so to be of use. Licorice is one of the most commonly used herbs in Western herbal medicine.
Liquorice has been used in medicine for more than 4000 years. The earliest record of its use in medicine is found in ‘code Humnubari’ (2100 BC). The drug was also mentioned by Theophrastus and Dioscorides. In traditional Siddha system of medicine, liquorice is used as a demulcent, expectorant, anti-tussive, laxative and sweetener . It is used with success for acute respiratory problems, gastric ulcers, gastritis, inflammatory conditions in general, and adrenal exhaustion. Components of licorice root have both estrogenic and anti-estrogenic activity. It is thus an important herb for treating hormone-related female problems.
Pharmacognosy & phytochemistry Pharmacognosy
Glycyrrhiza glabra Linn is a hardy perennial shrub, attaining a height up to 2.5 m . The leaves are compound, imparipinnate, alternate, having 4-7 pairs of oblong, elliptical or lanceolate leaflets. The flowers are narrow, typically papilionaceous, borne in axillary spikes, lavender to violet in colour. The calyx is short, campanulate, with lanceolate tips and bearing glandular hairs. It may be found peeled or unpeeled. The pieces of root break with a fibrous fracture, revealing the yellowish interior with a characteristic odour and sweet taste .
Phytochemicals
The roots of Glycyrrhiza glabra Linn contain glycyrrhizin, which is a saponin that is 60 times sweeter than cane sugar; Flavonoid rich fractions include liquirtin, isoliquertin liquiritigenin and rhamnoliquirilin and five new flavonoids- glucoliquiritin apioside, prenyllicoflavone A, shinflavanone, shinpterocarpin and 1-methoxyphaseolin isolated from dried roots. Isolation and structure determination of licopyranocoumarin, licoarylcoumarin, glisoflavone and new coumarin-GU-12 also isolated. Four new isoprenoid-substituted phenolic constituents – semilicoisoflavone B, 1-methoxyficifolinol, isoangustone A, and licoriphenone isolated from roots [6]. A new prenylated isoflavan derivative, kanzonol R was also isolated . The Indian roots show various 2-methyliso - flavones, and an unusual coumarin, C liquocoumarin, 6 - acetyl- 5, hydroxy- 4 - methyl coumarin. Asparagine is also found. Glycyrrhizin is a saponin compound comprised of a triterpenoid aglycone, glycyrrhetic acid (glycyrrhetinic acid; enoxolone) conjugated to a disaccharide of glucuronic acid. Both glycyrrhizin and glycyrrhetic acid can exist in the 18a and 18b stereoisomers.
Physicochemical parameters
Total ash (not less than 7%), cid insoluble ash (not less than 2%), Sulfated ash (not less than 10%) Water soluble extractive (not more than 20%), Diluted alcohol-soluble Extractive, (not more than 25%), Moisture (5.25%), Ether extracts (16.85%), Albuminoids (37.00 %( containing nitrogen5.92%)) Soluble carbohydrates (31.00%) Woody fiber (5.05%) [3].
Pharmacological activity
Although a lot of pharmacological investigations have been carried out based on the ingredients present but a lot more can still be explored, exploited and utilized. A summary of the findings of these studies is presented below.
Anti-bacterial activity
Shirazi M.H. et al. had studied the in vitro inhibitory effects of G. glabra extract against the growth of Salmonella typhi, S. paratyphi B, Shigella sonnei, S. flexneri and enterotoxigenic E. coli (ETEC E. coli) was investigated using well and disc diffusion method. Salmonella paratyphi B showed no susceptibility to liquorice with concentrations lower than 7.5%, however all tested bacterial strains exhibited susceptibility to high concentration of liquorice [12]. The extracts of Glycyrrhiza glabra Linn roots showed various antibacterial activities (7-11 mm/20 µl inhibition zone) against the microorganisms tested. The alcohol extracts did not inhibit B. subtilis var. niger, B. brevis, E. faecalis. The ethyl acetate extracts did not inhibit B. subtilis or Y. enterocolitica, and the acetone extracts did not inhibit E. faecalis, L. monocytogenes. The chloroform extracts showed no inhibition effect against P. aeruginosaor Y. enterocolitica.
Antioxidant activity
Ashawat M.S. et al. had studied the relative reducing activity in terms of antioxidant activity of extracts was determined by using individual extract (15mg) as well as its combination with equal amount of ascorbic acid. The absorbance was measured at 700nm by making 500µg mL extract aliquot. Increased absorbance of the reaction mixture indicated increased antioxidant activity via reducing power with reference to equal amount of standard ascorbic acid. Visavadiya N. P. et al. showed antioxidant property of Glycyrrhiza glabra Linn root extracts using in vitro models. The hydroalcoholic extracts of Glycyrrhiza glabra Linn which exhibited different anti-inflammatory activities were evaluated by Herold A et al. for the possible mode of action by studying their antioxidant potential.
Enzyme inhibitory activity
Zuidhoff H. W. et al. had studies licorice methanolic extract has shown in vitro inhibition of the tyrosinase enzyme, with 21.2 µg/ml inducing 50% inhibition. Active principles able to inhibit tyrosinase act by modifying the action site of the enzyme, thus reducing its activity. Licorice root extract is known to inhibit tyrosinase].
Anti fungal activity
Hojo A and Sato J. were screening for antifungal compounds from various plant material, licorice ( Glycyrrhiza glabra Linn) extracts with 80% methanol (oil-based extract of licorice; OEL) was found to have high fungicidal effect against Arthrinium sacchari M001 and Chaetomium funicola M002, and its active compound was identified as glabridin (3-(2’,4’-dihydroxyphenyl)-8-dimethylpyrano [8,7-e]chroman).
OEL was effective against not only filamentous fungi but also some bacteria, especially thermo-resistant bacilli such as genera of Bacillus and Alicyclobacillus. Glabridin to be active against both yeast and filamentous fungi and also showed resistance modifying activity against drug resistant mutants of Candida albicans at a minimum inhibitory concentration of 31.25-250 microg/mL by Fatima A. et al.
Anti hyper glycemic activity
Kalaiarasi P. et al. had studies the antihyperglycemic effect of 18ß-glycyrrhetinic acid, aglycone of glycyrrhizin, on streptozotocin-diabetic rats. Diabetes was induced in adult male albino rats of the Wistar strain, weighing 180–200 g, by administration of streptozotocin (40 mg/kg of body weight) intraperitoneally. Diabetic rats showed increase of plasma glucose and glycosylated haemoglobin (HbA1c) and a decrease of plasma insulin and haemoglobin (Hb). Activities of gluconeogenic enzymes such as glucose 6-phosphatase, fructose 1, 6-bisphosphatase increased and glucokinase, glucose 6-phosphate dehydrogenase decreased in the liver along with glycogen. Oral administration of 18ß-glycyrrhetinic acid (50, 100, or 200 mg/kg/body weight) or glibenclamide (600 µg/kg/body weight) in 5% dimethyl sulfoxide, for 45 days, prevented the above changes and improved towards normalcy [17,18].
Anti malarial activity
Glycyrrhiza species in different amounts and has been shown to exhibit good antimalarial activity. In in vivo tests against P. yoelii in mice, oral doses of 1000 mg kg-1 resulted in the complete eradication of the malaria parasite and no toxicity was noted. This present review covers most of the recently-published nonalkaloidal natural compounds from plants with antiplasmodial and antimalarial properties, belonging to the classes of terpenes, limonoids, flavonoids, chromones, xanthones, anthraquinones, miscellaneous and related compounds.
Anti-viral and immunostimulatory effects
Most of the Glycyrrhiza phenols reduced the viable cell number of mock-infected and HIV-infected MT-4 cells to comparable extents ]. Recent studies carried out with rats, demonstrated that glycyrrhizin inhibited the Arthus phenomenon and the Schwartzman reaction, and that the alcoholic extract of licorice root inhibited type I allergic reactions induced by injection of Ascaris lumbricoides IgE-containing serum. The immuno stimulatory properties of glycyrrhizin were also studies Utsunomiya T. et al. BALB/c mice infected with influenza virus A2 (H2N2) were unable to survive 10 times the mean lethal dose (LD50) of virus. Glycyrrhizin has also been demonstrated as effective in the treatment of herpes simplex-induced encephalitis in mice. Licorice and glycyrrhizate compounds have long been used in the treatment of chronic viral hepatitis in China and Japan but the possible mechanism of anti-viral activity remains unknown. In vitro studies have demonstrated that glycyrrhizin is effective at inhibiting the growth of a host of viruses under culture conditions including pathogenic flaviviruses, alphaviruses and herpes simplex virus .
Memory enhancing activity
Dhingra D. et al. had studied to investigate the effects of Glycyrrhiza glabra Linn (popularly known as liquorice) on learning and memory in mice. Elevated plus-maze and passive avoidance paradigm were employed to test learning and memory. The dose of 150 mg/kg of the aqueous extract of liquorice significantly improved learning and memory of mice. Furthermore, this dose significantly reversed the amnesia induced by diazepam (1 mg/kg i.p.) and scopolamine (0.4 mg/kg i.p.). Anti-inflammatory and antioxidant properties of liquorice may be contributing favourably to the memory enhancement effect. Since scopolamine-induced amnesia was reversed by liquorice, it is possible that the beneficial effect on learning and memory was due to facilitation of cholinergic-transmission in mouse brain. In the present investigation, Glycyrrhiza glabra Linn has shown promise as a memory enhancing agent in all the laboratory models employed [27].
Expectorant activity
While the specific mechanism of action remains unknown, Glycyrrhiza has been shown to work as effectively as codeine in the throat, decreasing irritations and producing expectorant effects. One proposed explanation is that in the same way that carbenoxolone, a semisynthetic compound derived Murray from Glycyrrhiza, is able to stimulate gastric mucus secretion, it is also able to stimulate tracheal mucus secretions and hence produce demulcent and expectorant effects. Licorice is a helpful remedy for coughs as it facilitates the movement of mucus from the respiratory tract].
Spasmolytic activity
Mills S. Y. et al. showed liquiritin present in the roots of Glycyrrhiza is inactive as an anti-spasmodic. However when hydrolysed by heat and converted to isoliquiritigenin, it was shown to exhibit strong spasmolytic activity.
Antiallergic activity
Glycyrrhiza glabra Linn (Glycyrrhizin, 18ß glycyrrhetinic acid and Liquiritigenin) have antiallergic activity, which can relive IgE – induced allergic diseases such as dermatitis and asthma.
Anti ulcer activity
Pepticare, a herbomineral formulation of the Ayurveda medicine consisting of the herbal drugs: Glycyrrhiza glabra Linn, Emblica officinalis and Tinospora cordifolia, was tested for its anti-ulcer and anti-oxidant activity in rats. Bafna PA were studied that effects of various doses (125, 250, 500 and 1000mg/kg, p.o.) of Pepticare on gastric secretion and gastric ulcers in pylorus-ligation and on ethanol-induced gastric mucosal injury in rats. Pepticare possesses anti-ulcer activity, which can be attributed to its anti-oxidant mechanism of action. Glycyrrhizic acid and its aglycon occurs in the form of the two stereoisomers, 18ß (cis) and 18? (trans). The 18ß GA isomer extracted from the root of licorice have anti viral, expectrorant, antitumor and antiulcer effects .
Perhaps the most predominant and consistent medicinal use for licorice has been as a demulcent for the digestive system. Indeed, carbenoxolone, a widely used pharmaceutical treatment for gastric ulcers, is a synthetic derivative of glycyrrhetic acid. The anti-ulcer activity of deglycyrrhizinated licorice Bennett A et al] was demonstrated using a rat model of aspirin-induced gastric mucosal damage. Clinical studies evaluating the efficacy of deglycyrrhizinated licorice suggest that several components exist in the extract which promote gastric healing, although inconsistencies are apparent between these studies [35, 36].
Hepatoprotective effecets
Watari N. studied that in animal and human models glycyrrhetic acid plays a protective role when liver cells are challenged. It decreases inflammatory states by reducing cytokines like tumor necrosis factor-alpha and increasing protective antioxidants like heme oxygenase-1. These shielded tissues release fewer markers of liver damage, repairing and regenerating themselves more rapidly.
The hepatoprotective properties of glycyrrhizin in hepatotoxin treated mice. In this study, animals were administered the hepatic carcinogen 3’- methyl-4-dimethyl-aminoazobenzene in the diet and injected 1mg glycyrrhizin twice per week for a period of three months. Animals treated with glycyrrhizin had a reduced incidence of hepatic cells showing morphological evidence of injury, including degenerated mitochondria, increased number of lysosomes, atrophied Golgi apparatus, pseudonuclear inclusions and increased mitotic cells.
Glycyrrhizin, at concentrations of 25–200 µg/ml, was found to significantly inhibit the CCl4-induced release of AST and LDH. The authors speculated that this function was due to an alteration of membrane fluidity by the glycyrrhizin, or perhaps an inhibition of CCl4-induced membrane lipid peroxidation. Glycyrrhizin exhibited no significant suppressive activity of free radical generation, whereas 18ß-glycyrrhetic acid inhibited this activity at 1mg/ml. Hepatoprotective mechanism of glycyrrhizic acid is due to its aglycone, 18ß-glycyrrhetic acid, which inhibits both free radical generation as well as lipid peroxidation.
The in vivo protection of glycyrrhizin against CCl4- induced hepatotoxicity was more recently illustrated by Jeong . Extracts of herbal plants Glycyrrhiza glabra Linn (GL), they showed a novel hepatoprotective effects against diclofenac –induced hepatotoxicity in rats . Glycyrrhizin reduced the mortality of acetaminophen overdosed mice more effectively, attenuate acetaminophen-induced hepatotoxicity, and reduced the number and area of ?-GT positive foci, thus protecting liver function was illustrated by Xu-ying.
Anticonvulsant
The anticonvulsant activity of ethanolic extract of roots and rhizomes of Glycyrrhiza glabra Linn (10, 30, 100 and 500 mg/kg, i.p.) in mice was assessed using maximum electroshock seizure (MES) test and pentylenetetrazol (PTZ) using albino mice. The lithium-pilocarpine model of status epileptics was also used by Shirish DA et al. to assess the anticonvulsant activity in rats. The dose of 100 mg/kg afforded protection to all animals. The extract also protected rats against seizures induced by lithium-pilocarpine.
Antiinflammatory
Glycyrrhetinic acid inhibits the enzyme 11-beta-hydroxy steroid dehydrogenase, which is responsible for converting cortisol, the active form into its inactive metabolites.
Thus inhibition of the enzyme by glycyrrhetinic acid significantly increases the levels of cortisol and also stimulation of the glucocorticoid receptors. This in turn potentiates the action of hydrocortisone, the main glucocorticoid secreted by the adrenal cortex. Hydrocortisone is associated with, and accounts for glyrrhizin and glycyrrhetinic acid’s anti-inflammatory.
Anti-carcinogenic effects
Wang ZY Studied to evaluate the potential anti-carcinogenic effects of licorice extract and glycyrrhizate compounds. An early report on the anti-mutagenic effects of glycyrrhizin and glycyrrhetic acid demonstrated, using a modified Ames test, that both of these compounds inhibited the mutagenicities of 3-amino-1-methyl-5H-pyrido[ 2,3-b]indol (Trp-p-2), 2-acetyl aminofluorene, and benzo(a)pyrene, in the presence S9 fraction hepatic enzymes. Ikken Y et al. speculate that glycyrrhetic acid may act by inhibiting the metabolic activation of some mutagens. Both licorice extract and glycyrrhizin inhibited the mutagenic effects of Trp-p-1 and Trp-p-2 in S. typhimurium TA98 whereas licorice extract exerted a moderate to strong antimutagenic effect against several N-nitrosamine mutagens.
Anti-cariogenic studies
Glycyrrhizin could significantly reduce the growth and acid production of Streptococcus, Actinomyces, and Bacterionema species. In contrast to these results, Segel R et al. reported that neither licorice “juice,” nor glycyrrhizin inhibited the growth of seven Streptococcus mutans strains. In the presence of sucrose, 0.5–1% glycyrrhizin had no effect on growth, but significantly inhibited bacterial adherence to glass by nearly 100% at the highest concentration tested]. The buffering capacity of glycyrrhizin was not sufficient to affect the fall in pH caused by bacterial sucrose degradation. In an additional study evaluating the mechanism of the anti-adherent property of glycyrrhizin, examined by Sela MN et al its effect on bacterial glucosyltransferase activity - an enzyme required in the formation of insoluble glucans required in plaque development.
Miscellaneous studies
Glycyrrhizin is classified as a saponin compound, and this property has been tested to determine its interaction with cellular membranes of erythrocytes and hepatic lysosomal preparations. Glycyrrhizin was found to protect erythrocytes against the hemolysis induced by other saponin compounds including digitonin, excin, tomatin, and saponin A. Glycyrrhizin was found to be as efficacious against the sapogenins digitogenin, tomatidine and sapogenin A, indicating that its mechanism of action is not the result of the inhibition of membrane glycosidases of erythrocytes. The possibility remains that glycyrrhizin prevents access of hemolysin to its receptor, or alters membrane fluidic dynamics at these high concentrations. To test this possibility, Nakagawa K investigated the effects of glycyrrhizin on the release and activity of acid phosphatases from hepatic lysosomal preparations. The reduction of lysosomal acid phosphatase activity was due to its release from the lysosomes rather than a direct inhibition of the enzyme suggesting an alteration in membrane fluidity].
Regulatory assessment of Glycyrrhiza glabra Linn
Licorice and licorice derivatives, including ammoniated glycyrrhizin are generally recognized as Safe (GRAS) for use in foods by the U.S. FDA (21 CFR 184.1408). This chapter of the regulations includes descriptions, specifications, and maximum use levels for licorice and licorice derivatives.
FDA assumes that glycyrrhizin levels in foods do not pose a health hazard, provided that these foods are not consumed in excess or by individuals who are sensitive to low levels of glycyrrhizin. Licorice extract and its derivatives are also approved for use in some over-the-counter drugs (21 CFR 310.528; 310.544; 310.545), and licorice is included as a GRAS ingredient in animal feeds (21 CFR 582.10; 582.20). Glycyrrhizinic acid was evaluated during a more recent JECFA meeting . Although a formal ADI was not established, the committee indicated that consumption of 100mg/day would be unlikely to cause adverse effects in the majority of adults and recognized that a subset of the population may be more susceptible to its physiological effects even at lower doses. Both the Council of Europe and the UK Food Additive and Contaminants Committee consider licorice as a natural plant product intended for use in small quantities as a food additive with the intention that its consumption be limited by the glycyrrhizin levels and not to exceed those occurring naturally in foods [51]. A limit of less than 50 ppm glycyrrhizin was established by these organizations.
Conclusion
Licorice (Glycyrrhiza glabra Linn) root and its extract such as glycyrrhizin have a long history of use in traditional medicines, folk remedies and as a sweetening and flavouring agent. Pharmacological studies have evaluated several of the traditional health claims behind licorice use although many of these reports have produced inconsistent results.
Carbenoxolone, an analogue of glycyrrhetic acid, has shown success in clinical trials for gastric and duodenal ulcers, but the potential development of pseudoaldosteronism has limited its use. Deglycyrrhizinated licorice has also shown some effect in the treatment of gastrointestinal ulcers, suggesting the presence of active ingredients other than glycyrrhizin, although other studies have shown it has no beneficial effects.
Licorice and glycyrrhizinate compounds have been used as antibacterial, antioxidant, antimalarial, antispasmodic, anti-inflammatory and anti hyper glycemic properties. Various other effects like antidiuretic, antihapatotoxic, antifungal and herpes simplex viral infections such as hepatitis. Although these studies indicated favourable changes in hepatic function, they do not all demonstrate a reduction in viral load. The potential mechanisms of anti-ulcer and anti-viral action of glycyrrhizin are unknown; however, modulation of the immune response seems to be indicated. It can be concluded that Glycyrrhiza glabra Linn can be used as prophylactic as well as therapeutic drug for major body ailments at any age group irrespective of sex.
Acknowledgements
Authors are grateful to the staff of library of Suresh Gyan Vihar University and Rajasthan University, Jaipur, for allowing and accessing the documentation on rational and quality use of traditional medicines.
- Authors are faculty Gyan Vihar School of Pharmacy, Suresh Gyan Vihar University, Jaipur