No abstract

Licochalcone A, a species-specific and characteristic retrochalcone ingredient of Glycyrrhiza inflata root, has been shown to possess multiple bioactive properties. However, its muscle relaxant activity has not been reported previously. Licochalcone A showed a concentration-dependent relaxant effect on the contraction induced by carbachol (50% effective concentration (EC50) = 5.64 +/- 1.61 microM), KCl (EC50 5.12 +/- 1.68 microM), BaCl2 (EC50 1.97 +/- 0.48 microM) and A23187 (EC50 2.63 +/- 2.05 microM). Pretreatment with licochalcone A enhanced the relaxant effect of forskolin, an adenylyl cyclase activator, on the contraction in a similar manner to 3-isobutyl-1-methylxanthine (IBMX), a phosphodiesterase (PDE) inhibitor. Furthermore, the IC50 (22.1 +/- 10.9 microM) of licochalcone A against cAMP PDE was similar to that of IBMX (26.2 +/- 7.4 microM). These results indicated that licochalcone A may have been responsible for the relaxant activity of G. inflata root and acted through the inhibition of cAMP PDE.

In China, the collection of wild Glycyrrhiza uralensis, one of the raw materials of Chinese licorice, has been restricted to prevent desertification. To compensate for the reduced supply of wild Glycyrrhiza plants, cultivation programs of G. uralensis have been initiated in eastern Inner Mongolia. The goal of the present study was to compare the chemical and pharmacological properties of cultivated G. uralensis roots to those of licorice prepared from wild Glycyrrhiza plants. The antispasmodic effect of boiled water extract of 4-year-old cultivated G. uralensis roots and licorice on carbachol-induced contraction in mice jejunum was similar (ED 50 : 134؎21 m mg/ml vs. 134؎16 m mg/ml). In addition, glycycoumarin content, which is an antispasmodic and species-specific ingredient of G. uralensis, was similar when comparing the boiled water extracts of 4-year-old cultivated roots and licorice (0.10؎0.02% vs. 0.10؎0.06%). These data suggest that cultivated G. uralensis roots may be an adequate replacement for the generation of licorice in the context of the restriction of wild Glycyrrhiza plant collection.