Isolation and determination of saponin hydrolysis products from Medicago sativa using supercritical fluid extraction, solid‐phase extraction and liquid chromatography with evaporative light scattering detection

Abstract

Saponins are widespread secondary metabolites with various beneficial properties: fungicidal, antibacterial, antiviral, and anticancer. Alfalfa saponin molecules contain mainly: medicagenic acid, hederagenin, bayogenin, and soyasapogenol B. Structural diversity of saponins makes their determination in Medicago sativa extracts very difficult. The most popular determination technique is high‐performance liquid chromatography applied with evaporative light scattering detection. Qualitative and quantitative analysis of sapogenins from Medicago sativa by high‐performance liquid chromatography with evaporative light scattering detection required hydrolysis and purification of extracts obtained by supercritical fluid extraction. Hydrolysis of saponins with concentrated hydrochloric acid provided high concentration of medicagenic acid. In the purification process, satisfactory results were obtained for solid‐phase extraction using octadecyl. Recoveries were from 71 to 99% with a standard deviation from 2 to 8. Hydrolysis with concentrated hydrochloric acid was the only method that allowed identification of all four analyzed sapogenins. Moreover, it is characterized by a short time of preparation, simplicity of execution, a small amount of the sample and solvents. The hydrolysis and purification methods coupled with high‐performance liquid chromatography and evaporative light scattering detection can be successfully used for qualitative and quantitative analysis of the main saponins present in Medicago sativa plant extracts obtained by supercritical fluid extraction.

Distribution of sapogenins in morphological Medicago sativa L. parts: Comparison of various extraction techniques

“…They consist of sugar (glycon) and nonsugar parts (sapogenin) [1][2][3][4][5][6][7]. They consist of sugar (glycon) and nonsugar parts (sapogenin) [1][2][3][4][5][6][7].…”

“…Holothuroidea, Asteroidea, and Porifera [5,[8][9][10][11][12][13]. They are triterpenic pentacyclic glycosides with the following major sapogenins: medicagenic acid, hederagenin, bayogenin, and soyasapogenol B [3,7]. These compounds are used as preservatives, surfactants, Article Related Abbreviations: ASE, accelerated solvent extraction; ELSD, evaporative light scattering detection; SFE, supercritical fluid extraction.…”

“…Then, purified sapogenins such as medicagenic acid, bayogenin, hederagenin, and soyasapogenol B have been determined by HPLC coupled with evaporative light scattering detection (ELSD) [7]. In our recent publication, we have presented the new indirect method for saponins determination based on their acid hydrolysis to sapogenins and sugars.…”

“…The selection of an appropriate extraction technique and solvent is crucial for isolation of saponins from plant material [1][2][3]7]. Maceration is the most commonly used extraction method for this group of compounds.…”

“…Hydrolysis of saponins is carried out using hydrochloric acid in various concentrations [1,7,[23][24][25][26]. For this purpose, SPE with octadecyl sorbent was commonly used [7,24,25]. For this purpose, SPE with octadecyl sorbent was commonly used [7,24,25].…”