Study of an Acid-Free Technique for the Preparation of Glycyrrhetinic Acid from Ammonium Glycyrrhizinate in Subcritical Water

Abstract

The aim of this work was to study an application of a previously developed expedient acid-free technique for the preparation of glycyrrhetinic acid from ammonium glycyrrhizinate that requires no use of acids and toxic organic solvents. Subcritical water that serves as a reactant and a solvent was used in order to obtain glycyrrhetinic acid in good yields starting from ammonium glycyrrhizinate. It has been shown that variation of only one parameter of the process (temperature) allows alteration to thecomposition of the hydrolysis products. A new method was used for the synthesis of glycyrrhetinic acid (glycyrrhizic acid aglycone) and its monoglycoside. HPLC combined with mass spectrometry and NMR spectroscopy were used to determine the quantitative and qualitative compositions of the obtained products. The method developed for the production of glycyrrhetinic acid in subcritical water is environmentally friendly and faster than conventional hydrolysis methods that use acids and expensive and toxic organic solvents. The proposed technique has a potential for the future development of inexpensive and environmentally friendly technologies for production of new pharmaceutical plant-based substances.

New fast “One-pot” Technique for the Production of Glycyrrhetinic Acid from the Roots of licorice (Glycyrrhiza glabra)

“…It can be assumed that an increase in temperature above 210°C leads to a significant decrease in the yield of GLA due to its thermal destruction. The obtained results are in agreement with the previous data recorded in the study of hydrolysis of GA to GLA in a medium of SBW [14]. These data allow us to choose a temperature of 200°C as the temperature at which the effect of the thermal decomposition of GLA on its yield is negligible.…”

“…Dependence of the amount of GA and GLA in products obtained from the roots of licorice in SBW (without any acids additives) in the temperature range from 120°C to 250°C demonstrates an increase in the yield of GLA (from 0.6 to 17.1 mg/g) with increasing temperature to 200°C is accompanied by a decrease in the yield of GA in this temperature range. The decrease in the amount of GA, as was shown earlier [14], is caused by hydrolysis processes in which the SBW is a catalyst. A further increase in temperature led to a decrease in the yield of GLA.…”

“…At the next stage, the yields of GLA were studied using the "onepot" technique in the SBW-medium. Our previous studies [14] showed that the conversion of GA to GLA using the SBW-medium was the most complete in the temperature range from 180 to 220°C [14]. Therefore, the temperature dependence of the yield of GA and GLA, after treatment of the licorice roots in the medium of the SBW, was studied in this temperature range.…”

“…Recent results of the authors [14] on the synthesis of GLA from the ammonium glycyrrhizinate demonstrated the possibility of using the SBW to produce GLA without the use of acids and toxic solvents.…”

Production of 11-Oxo-β-Amyrin in Saccharomyces cerevisiae at High Efficiency by Fine-Tuning the Expression Ratio of CYP450:CPR

“…This low content makes the extraction of GA uneconomic. Thus, GA is primarily produced by the acid hydrolysis of GL, usually causing environmental pollution . The slow growth of liquorice plantations limited the supply of GL and their derivatives and restricted their application.…”