Liquorice

Chinese Name: Gan Cao
Medical Name: Radix Glycyrrhizae
Latin Name: Glycyrrhiza uralensis Fisch. of the family Leguminosae
Origin: Root and rhizome, dried or stir-baked with honey.
Taste: Sweet

Quotes from Chinese historical sources

JING-YUE'S FULL EDITION OF THE STANDARDIZED MATERIA MEDICA: "Liquorice is a neutralizing agent, able to harmonize the effects of other herbs. It can work with antitoxins to alleviate poisons, it can moderate the effects of harsh medicines, it can be used to assist the effects of herbs in relieving exterior syndromes, it can slow the effect of purgatives... used with winvigorating herbs it can promote the qi, used with blood tonics it can help the blood. It can function anywhere and with any herb."

THE HERBAL CLASSIC OF SHEN NONG: "Liquorice is sweet and mild in flavour. It is mainly used to treat pathogenic factors, chills and fever within the internal organs, strengthen the physique, enhance muscle, increase strength... and to relieve internal heat and fevers. Taken for a long time, it will relax the body and lengthen one's life."

Western Research

Eur J Pharmacol. 2003 May 23;469(1-3):159-63.
Antitussive principles of Glycyrrhizae radix, a main component of the Kampo preparations Bakumondo-to (Mai-men-dong-tang).
Kamei J, Nakamura R, Ichiki H, Kubo M.
Department of Pathophysiology and Therapeutics, School of Pharmacy and Pharmaceutical Sciences, Hoshi University, 4-41, Ebara 2-chome, Shinagawa, Tokyo 142-8501, Japan.
We attempted to elucidate the antitussive principles of Glycyrrhizae radix, a main component of Bakumondo-to (Mai-men-dong-tang). Although the 50% methanol-eluted fraction (100 mg/kg, p.o.) caused a more than 60% reduction in the number of capsaicin-induced coughs, neither the water-eluted nor 100% ethanol-eluted fractions of water extract of G. radix had antitussive effects. The water extract of G. radix contained high levels of liquiritin, liquiritin apioside, isoliquiritin, isoliquiritin apioside and glycyrrhizin. On the other hand, the 50% methanol-eluted fraction contained mainly liquiritin and liquiritin apioside, but not the other compounds. Liquiritin apioside (3-30 mg/kg, p.o.), but not liquiritin, isoliquiritin, isoliquiritin apioside or glycyrrhizin, dose-dependently inhibited the number of coughs. Methysergide, a serotonin receptor antagonist, antagonized the antitussive effect of liquiritin apioside. However, the antitussive effect of liquiritin apioside was not antagonized by naloxone. Pretreatment with glibenclamide (3 mg/kg, i.p.), an ATP-sensitive potassium channel blocker, also significantly reduced the antinociceptive effect of liquiritin apioside. These results suggest that G. radix contains a potent antitussive compound, liquilitin apioside, whose antitussive effect may depend on both peripheral and central mechanisms.

Am J Chin Med. 2005;33(5):817-29.
Activity of wen-pi-tang, and purified constituents of rhei rhizoma and glycyrrhizae radix against glucose-mediated protein damage.
Nakagawa T, Yokozawa T, Kim YA, Kang KS, Tanaka T.
Institute of Natural Medicine, Toyama Medical and Pharmaceutical University, Toyama, Japan.
Wen-Pi-Tang, an Oriental medical prescription composed of Rhei Rhizoma, Ginseng Radix, Aconiti Tuber, Zingiberis Rhizoma and Glycyrrhizae Radix, is used clinically as a medicine to treat renal failure. This study was conducted to examine the inhibitory activity of the five crude drug components of Wen-Pi-Tang and several pure compounds isolated from Rhei Rhizoma and Glycyrrhizae Radix against the protein glycation reaction. Rhei Rhizoma exerted the most potent activity, Zingiberis Rhizoma and Glycyrrhizae Radix showed relatively moderate activity, whereas Aconiti Tuber and Ginseng Radix showed weak activity. On the other hand, of 20 compounds obtained from Rhei Rhizoma and Glycyrrhizae Radix, tannins, especially rhatannin, RG-tannin and procyanidin B-2 3,3'-di-O-gallate, showed significantly strong activities that were more effective than the positive control, aminoguanidine. Some flavones such as licochalcone A and licochalcone B, and anthraquinones such as emodin and aloe-emodin, also showed inhibitory activity. These findings may help to explain, at least in part, certain pharmacological activities of Wen-Pi-Tang, whose clinical efficacy against renal failure is already recognized.

Phytomedicine 2000 Jan;6(6):439-45
Protective effects of Glycyrrhizae radix extract and its compounds in a renal hypoxia (ischemia)-reoxygenation (reperfusion) model.
Yokozawa T, Liu ZW, Chen CP.
Institute of Natural Medicine for Wakan-Yaku, Toyama Medical and Pharmaceutical University, Japan.
Glycyrrhizae radix water extract (GRWE) and its two major constituents significantly suppressed LDH leakage and MDA release. They may be promising for amelioration of hypoxia (ischemia)-reoxygenation (reperfusion) injury and improvement of renal function by acting directly or indirectly as antioxidant and oxygen radical-scavenging agents.