Effect of solvent and extraction technique on composition and biological activity of Lepidium sativum extracts.

The aim of this study was to evaluate chemical and biological potential of garden cress (Lepidium sativum L.) to receive valuable plant extracts with potential application in pharmacy or food industry. Four techniques of extraction and three environmentally friendly solvents such as water, supercritical CO2 and ethanol have been tested. Biological activity and chemical profile were evaluated in obtained extracts. GC/MS analysis showed that SFE extract from dried sprouts of L. sativum was especially rich in such glucosinolate derivatives as benzyl cyanide and benzyl thiocyanate. However, the extract obtained from freeze-dried sprouts by SFE with addition of 96% ethanol as co-solvent was especially rich in flavonoids and simultaneously exhibited the best antimicrobial activity. Comparison of MALDI-TOF-MS spectra of all obtained extracts clearly indicates that both SFE and maceration with water are the most selective techniques of extraction due to the lowest level of interfering substances with high molecular masses.

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.

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.

Comparison of Various Extraction Techniques of Medicago sativa: Yield, Antioxidant Activity, and Content of Phytochemical Constituents.

Medicago sativa L. (M. sativa) is a source of many valuable secondary metabolites. Extraction yield and the concentration of phenolics, flavonoids, and saponins, as well as antioxidant potential were determined in extracts from different parts of M. sativa obtained using extraction methods such as maceration, ultrasound-assisted extraction (UAE), accelerated solvent extraction (ASE), and supercritical fluid extraction (SFE). The concentrations of the listed groups of compounds were spectrophotometrically determined and confirmed by HPLC-MS. The results showed that ASE of flowers with 70% ethanol (EtOH) provided the highest yield of extraction (47.5 ± 4.0%), whereas the lowest yield was obtained in stems (4.0 ± 0.2%). The 70% EtOH extract from flowers showed the highest phenolic content [48.4 ± 4.6 mg gallic acid equivalents/g dry matter (DM)], as well as the highest antioxidant activity. The highest total flavonoid content (139.0 ± 7.1 mg rutin equivalents/g DM) was observed in the extract from leaves obtained through SFE. This extract was also especially rich in saponins [622.2 ± 30.3 mg oleanolic acid equivalents (OAE)/g DM]. However, the lowest compound content was observed in maceration extracts from stems (54.6 ± 27.0 mg OAE/g DM). The results suggest that EtOH extracts from alfalfa flowers and SFE extracts from M. satvia leaves, especially, may serve as potential sources of natural antioxidants for nutraceuticals, food additives, and cosmetic ingredients.