Standardization of licorice roots: current issues

Abstract

BACKGROUND: Medicinal plant raw material Licorice roots contains a whole complex of biologically active compounds (triterpene saponins, flavonoids, etc.) and is widely used in medicine as raw materials for the production of anti-inflammatory and expectorant medications. However, despite its widespread use and well-studied chemical composition, the problems in the field of standardization of licorice roots remain urgent. The current pharmacopoeial method for determining the quantitative content of glycyrrhizic acid is multi-stage, it consists in the extraction of nitric acid with the use of 3% acetone solution, the addition of the concentrated ammonia solution to form a precipitate (ammonium salt of glycyrrhizic acid), its filtration and dissolution in water, followed by spectrophotometric determination. There are other methods for determining the content of this biologically active compound. They involve high performance liquid chromatography. No results for quantification of glycyrrhizic acid by this method in isocratic elution mode were found in the available scientific literature. AIM: The aim is to develop the method for determining the quantitative content of glycyrrhizic acid in licorice roots using high performance liquid chromatography in an isocratic elution mode. MATERIALS AND METHODS: The objects of the study were licorice roots harvested in 2018 in the Botanical Garden of Samara University, commercial samples of plant raw materials, state standard samples of monosubstituted ammonium salt of glycyrrhizic acid (glycyram, PM 42-0034-00) and the work glycyrrhizic acid standard. High performance liquid chromatography analysis was carried out by using a Milichrom-6 chromatograph. RESULTS: As a result of the investigation, the method for determining the quantitative content of glycyrrhizic acid by reversed-phase high performance liquid chromatography with UV detection (258 nm) was developed. The mobile phase was acetonitrile: 1% acetic acid solution in water in the ratio of 40:60, the elution rate was 100 l/min. The optimal extraction conditions were selected: extractant was 40% ethyl alcohol, extraction for 60 minutes at the ratio of raw material-extractant was equal to 1:30. Validation analysis showed that the developed methods demonstrated satisfactory metrological indicators. CONCLUSIONS: The obtained results can be used to update the pharmacopoeial monograph Licorice roots.