Glycyrrhizin

Glycyrrhizin is the active principle of liquorice root. It is a powerful sweetener, 30–50 times as potent as sucrose (table sugar).

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Chemically, glycyrrhizin is a triterpenoid saponin glycoside being either the Ca2+ or K+ salt of glycyrrhizic (or glycyrrhizinic) acid. Upon hydrolysis, the glycoside loses its sweet taste and is converted to the aglycone glycyrrhetinic acid plus two molecules of glucuronic acid. The acid form is not particularly water soluble, but its ammonium salt is soluble in water at pH greater than 4.5.

Although sweet, the taste of glycyrrhizin is different from that of sugar. The sweetness of glycyrrhizin has a slower onset than sugar, and lingers in the mouth for some time. Additionally, its characteristic licorice flavor makes it unsuitable as a direct flavor substitute for sugar. Unlike the artificial sweetener aspartame, glycyrrhizin maintains its sweetness under heating.

In the United States, glycyrrhizin is classified as "generally recognized as safe" as a flavoring agent, although not as a sweetener. Glycyrrhizin is used as a flavoring in some candies, pharmaceuticals, and tobacco products.

In Japan, where concern over the safety of artificial sweeteners during the 1970s led to a shift towards plant-derived sugar substitutes, glycyrrhizin is a commonly used sweetener, often used in combination with another plant-based sweetener, stevia. However, glycyrrhizin appears to have some pharmacological side effects, and the Japanese government has asked its citizens to limit their consumption to 200 milligrams per day.

Health effects

Recently researchers have demonstrated that doses of licorice root extract, delivering the constituent glycyrrhizin in amounts similar to that contained in standard medical doses of the root, rapidly and significantly lowered levels of circulating testosterone in males.^[1]

Glycyrrhizin and other licorice root products have been used for numerous medical purposes, particularly treatment of peptic ulcers and as an expectorant. The triterpene derivative of hydrolyzed glycyrrhizin, glycyrrhetinic acid, is itself effective in treatment of peptic ulcer. However, because it inhibits the metabolism of cortisol, glycyrrhetinic acid indirectly raises blood pressure via increased sodium level.

Although licorice is known to produce anti-inflammatory effects, it is uncertain whether that is due to glycyrrhizin, glycyrrhetinic acid, or some other licorice derivative.

Glycyrrhizin inhibits liver cell injury caused by many chemicals and is used in the treatment of chronic hepatitis and cirrhosis in Japan. It also inhibits the growth of several DNA and RNA viruses, inactivating herpes simplex virus particles irreversibly.

The most widely reported side effects of glycyrrhizin use are hypertension and edema (water retention). Deglycyrrhizinated licorice is a preparation used for treating ulcers which has had the glycyrrhizin removed in order to avoid the side effects.

A prolonged usage of licorice can also cause the formation of cataracts.

See also

glycyrrhetinic acid

References

• Saponin Glycosides, by Georges-Louis Friedli, URL accessed Dec 2007.

1. ^ Glycyrrhiza: Licorice root and testosterone