Evaluation of the safety and efficacy of Glycyrrhiza uralensis root extracts produced using artificial hydroponic-field hybrid cultivation systems II: comparison of serum concentration of glycyrrhetinic acid serum concentration in mice

O-glycosyltransferases from Homo sapiens contributes to the biosynthesis of and Glycyrrhizin in Saccharomyces cerevisiae

Glycyrrhizin (GL) and Glycyrrhetic Acid 3-O-mono-β-D-glucuronide (GAMG) are the typical triterpenoid glycosides found in the root of licorice, a popular medicinal plant that exhibits diverse physiological effects and pharmacological manifestations. However, only few reports are available on the glycosylation enzymes involved in the biosynthesis of these valuable compounds with low conversion yield so far. In mammals, glycosyltransferases are involved in the phase II metabolism and may provide new solutions for us to engineer microbial strains to produce high valued compounds due to the substrate promiscuity of these glycosyltransferases. In this study, we mined the genomic databases of mammals and evaluated 22 candidate genes of O-glycosyltransferases by analyzing their catalytic potential for O-glycosylation of the native substrate, glycyrrhetinic acid (GA) for its glycodiversification. Out of 22 selected glycosyltransferases, only UGT1A1 exhibited high catalytic performance for biosynthesis of the key licorice compounds GL and GAMG. Molecular docking results proposed that the enzymatic activity of UGT1A1 was likely owing to the stable hydrogen bonding interactions and favorite conformations between the amino acid residues around substrate channels (P82~R85) and substrates. Furthermore, the complete biosynthesis pathway of GL was reconstructed in Saccharomyces cerevisiae for the first time, resulting in the production of 5.98 ± 0.47 mg/L and 2.31 ± 0.21 mg/L of GL and GAMG, respectively.

Effect of hot water extract of a glycyrrhizin-deficient strain of Glycyrrhiza uralensis on contact hypersensitivity in mice

To evaluate the medicinal properties of a glycyrrhizin (GL)-deficient strain of Glycyrrhiza uralensis, we investigated the anti-allergic effect of the hot water extract obtained from its roots on contact hypersensitivity in mice, and compared it with that of the hot water extract of a commercial crude drug, Glycyrrhiza Radix. The hot water root extract of the GL-deficient strain contained glucoglycyrrhizin (GGL) and rhaoglucoglycyrrhizin (RGL) instead of GL, and it showed anti-allergic activity against contact hypersensitivity in a fashion similar to that of the crude drug extract. We further confirmed the presence of glycyrrhetinic acid (GA), a major metabolite of GL, in mice serum after oral administration of the hot water root extract of a GL-deficient strain. We demonstrated that GGL underwent hydrolysis by intestinal microflora of mice to form GA. These results suggest that a GL-deficient strain of G. uralensis is a useful medicinal resource since the glycosides of GA work in a fashion similar to that of GL when orally administered.

Evaluation of the safety and efficacy of Glycyrrhiza uralensis root extracts produced using artificial hydroponic and artificial hydroponic-field hybrid cultivation systems III: anti-allergic effects of hot water extracts on IgE-mediated immediate hypersensitivity in mice

To evaluate the safety and efficacy of Glycyrrhiza uralensis root extracts produced using artificial hydroponic and artificial hydroponic-field hybrid cultivation systems, we investigated anti-allergic action in mice using IgE-mediated immediate hypersensitivity. Hot water extracts obtained from the roots of Glycyrrhiza uralensis cultivated using two systems were orally administered at a dose of 100 mg/kg as glycyrrhizin (GL) and compared with the commercial crude drug, Glycyrrhizae Radix. Both the artificial hydroponic and artificial hydroponic-field hybrid cultivated root extracts showed anti-allergic effects on IgE-mediated immediate hypersensitivity in mice, as did the commercial crude drugs. These results highlight the potential for artificially cultivated roots of Glycyrrhiza uralensis to be used as an alternative medicinal source.