INTRODUCTION:

Despite the developments in various field of medicine, oral infections, dental caries and periodontal diseases are still considered as serious public health problems and inflict a large burden to health care services around the world especially in developing countries (1-3). Bacterial plaque or biofilms accumulated on teeth surfaces that are composed of native oral microbiota, are the primary etiological agents for oral diseases which may resulted in teeth loss if left untreated (4, 5). On the other hand, development of resistance against antibiotics and antiseptics is a growing cause of concern which limited the preventive measurement. Therefore, there is a permanent need to search for new antimicrobial agents (6).

Glycyrrhiza glabra, also known as Liquorice and sweet wood, is native to the Mediterranean and certain areas of Asia. Historically, the dried rhizome and root of this plant were employed medicinally by the Egyptian, Chinese, Greek, Indian, and Roman civilizations as an expectorant and carminative. In modern medicine, Liquorice extracts are often used as a flavoring agent to mask bitter taste in preparations, and as an expectorant in cough and cold preparations. Liquorice extracts have been used for more than 60 years in Japan to treat chronic hepatitis (7).

NEED FOR AN ALTERNATIVE MEDICINE:

Streptococcus mutans is the most common cariogenic bacteria associated with dental caries. Today it is believed to be the chief etiologic agent in human dental caries. This bacterium has the ability to metabolize dietary sucrose and synthesize glucan by cell surface and extracellular glucosyltransferase. This glucan is an insoluble sticky or slimy gel relatively inert and resistant to bacterial hydrolytic enzymes which causes plaque to adhere tenaciously to tooth surfaces (8). Streptococccus mutans and other organisms in the plaque produce organic acids such as lactic acid that gradually destroy the enamel to form a cavity (9).

Enterococcus faecalis, gram positive cocci is associated with different forms of periradicular diseases including primary endodontic infections and persistent infections. It has been associated with asymptomatic chronic periradicular lesions. E. Faecalis is responsible for failed root canal treatment cases and is resistant to calcium hydroxide due to its proton pump (10). E faecalis can also survive by genetic polymorphism and its ability to bind to dentin, invade dentinal tubules, and survive starvation (11). According to Charles H Stuat et al, the most effective method to eradicate E faecalis is the use of sodium hypochlorite and 2% chlorhexidine3. Sodium hypochlorite is extremely toxic to periapical tissues if injected beyond apex (12).Presence of inflammatory exudate and killed micro organisms can inhibit the action of chlorhexidine in root canals. Studies have shown that the combination of NaOCl and chlorhexidine can form para-chloroaniline (PCA), a product which is potentially carcinogenic and occludes dentinal tubules (13). Hence an alternative medicine with antimicrobial activity is used for endodontic treatment.

CHEMICAL CONSTITUENTS:

Constituents that bring about the pharmacological effects of G. glabra are Saponins, Flavonoids, Alkaloids, Tannins, Steroids, etc. The major constituents are triterpenesaponins. Glycyrrhizin is generally regarded as the active principle of G. glabra and is responsible for its sweetness, which is 50 times more than that of sucrose. Glycyrrhizin (glycyrrhizic acid, glycyrrhizinic acid) is the major component (2–9%); minor components occur in proportions that vary depending on the species and geographical location. Glycyrrhizin occurs as a mixture of potassium and calcium salts. It is a monodesmoside, which on hydrolysis releases two molecules of D-glucuronic acid and the aglyconeglycyrrhetic (glycyrrhetinic) acid (enoxolone). Glabridin, liquiritigenin and Isoliquiritigenin, the lipophilic compounds present in G. glabra with comparatively lowmolecular weight are likely to be absorbed into blood and distributed to brain (14).

ANTIBACTERIAL ACTIVITY:

The ethanolic extract of G. glabra had effective MIC values against all oral bacteria especially S. mutans, A. viscosus, and E. faecalis and exhibited the highest MIC value against E. coli, so maybe antibacterial activity of G. glabra against gram positive bacteria was more than gram negative bacteria (2). Antibacterial activity of mixed extract including C. bursa-pastoris and G. glabra was evaluated and showed that the mixed extract was more effective against all bacteria than any single extracts that indicating the synergistic effect between these two extracts. The prevalence of oral infections, as one of the major problems in oral health, has caused increasing use of mouthwash products(14). Herbal mouthwashes, compared with chemical drugs, have fewer side effects and are more economical. This in-vitro study suggests C. bursa-pastoris and its mixture with G. glabra as a candidate may help us to control dental cavities and oral infections. The effects of this extract maybe more beneficial if it is incorporated in gum, toothpaste, mouthwash, and dental products to reduce plaque and dental caries (15).

PHARMACOKINETICS:

After oral administration of licorice in humans, the main constituent, glycyrrhizic acid, is hydrolyzed to glycyrrhetic acid by intestinal bacteria possessing a specialized ß-glucuronidase (16, 17). Glycyrrhetic acid is 200-1,000 times more potent an inhibitor of 11-ß-hydroxysteroid dehydrogenase (involved in corticosteroid metabolism) than glycyrrhizic acid; therefore, its pharmacokinetics after oral intake are more relevant. After oral dosing, glycyrrhetic acid is rapidly absorbed and transported via carrier molecules to the liver. In the liver it is metabolized to glucuronide and sulfate conjugates, which are subsequently rehydrolyzed to glycyrrhetic acid. Glycyrrhetic acid is then reabsorbed, resulting in a significant delay in terminal clearance from plasma.(18) After oral administration of 100 mg glycyrrhizin in healthy volunteers, no glycyrrhizin was found in the plasma but glycyrrhetic acid was found at < 200 ng/mL. In the 24-hour period after oral administration, glycyrrhizin was found in the urine, suggesting it is partly absorbed as an intact molecule (19,20).

CONCLUSION:
This review clearly labels the dental properties of Glycyrrhiza glabra. Many researches are being conducted in these ayurvedic herbs which show the diversion of the human search from allopathic to alternative medicines. This doesn’t mean that they are ineffective but due to inconclusive or incomplete remedy in many diseases and even the complicated side effects. Even though these herbs have side effects but comparatively minimal. In near future many properties may be revealed due to several research projects.

REFERENCE:

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Received on 21.03.2014 Modified on 20.04.2014

Research J. Pharm. and Tech. 7(7): July 2014 Page 821-822