The roots of the medicinal plant Aralia elata are rich in biologically active natural products, with triterpene saponins constituting one of their major groups. These metabolites can be efficiently extracted by methanol and ethanol. Due to their low toxicity, natural deep eutectic solvents (NADES) were recently proposed as promising alternative extractants for the isolation of natural products from medicinal plants. However, although NADES-based extraction protocols are becoming common in routine phytochemical work, their application in the isolation of triterpene saponins has not yet been addressed. Therefore, here, we address the potential of NADES in the extraction of triterpene saponins from the roots of A. elata. For this purpose, the previously reported recoveries of Araliacea triterpene saponins in extraction experiments with seven different acid-based NADES were addressed by a targeted LC-MS-based quantitative approach for, to the best of our knowledge, the first time. Thereby, 20 triterpene saponins were annotated by their exact mass and characteristic fragmentation patterns in the total root material, root bark and root core of A. elata by RP-UHPLC-ESI-QqTOF-MS, with 9 of them being identified in the roots of this plant for the first time. Triterpene saponins were successfully extracted from all tested NADES, with the highest efficiency (both in terms of the numbers and recoveries of individual analytes) achieved using a 1:1 mixture of choline chloride and malic acid, as well as a 1:3 mixture of choline chloride and lactic acid. Thereby, for 13 metabolites, NADES were more efficient extractants in comparison with water and ethanol. Our results indicate that new, efficient NADES-based extraction protocols, giving access to high recoveries of triterpene saponins, might be efficiently employed in laboratory practice. Thus, our data open the prospect of replacing alcohols with NADES in the extraction of A. elata roots.

The methods and solvents employed in routine extraction protocols essentially impact the composition of the resulting extracts, i.e., the relative abundances of individual biologically active metabolites and the quality and stability of the isolates. Natural deep eutectic solvents (NADESs) represent a new class of environmentally friendly solvents, which are recognized as promising extractants alternative to conventional organic liquids. However, their relative efficiencies when applied in different extraction workflows are still poorly characterized. Therefore, here, we compare the potential of three extraction methods for the extraction of biologically active natural products from Aralia elata var. mandshurica with selected natural deep eutectic solvents (NADESs) using a non-targeted metabolomics approach. The non-targeted metabolite profiling relied on reversed-phase ultra-high-performance liquid chromatography–high-resolution mass spectrometry (RP-UHPLC-HR-MS). The roots of A. elata were extracted by maceration, ultrasound-assisted extraction (UAE), and vibrocavitation-assisted extraction (VAE). Principal component analysis (PCA) revealed a clear separation of the extracts obtained with the three extraction methods employed with NADES1 (choline chloride/malic acid) and NADES2 (sorbitol/malic acid/water). Based on the results of the hierarchical clustering analysis obtained for the normalized relative abundances of individual metabolites and further statistical evaluation with the t-test, it could be concluded that NADES1 showed superior extraction efficiency for all the protocols addressed. Therefore, this NADES was selected to compare the efficiencies of the three extraction methods in more detail. PCA followed by the t-test yielded only 3 metabolites that were more efficiently extracted by maceration, whereas 46 compounds were more abundant in the extracts obtained by VAE. When VAE and UAE were compared, 108 metabolites appeared to be more abundant in the extracts obtained by VAE, whereas only 1 metabolite was more efficiently recovered by UAE. These facts clearly indicate the advantage of the VAE method over maceration and UAE. Seven of the twenty-seven metabolites tentatively identified by tandem mass spectrometry (MS/MS) were found in the roots of A. elata for the first time. Additional studies are necessary to understand the applicability of VAE for the extraction of other plant materials.

Introduction. Calcium is a key macroelement that ensures bone mineral density, muscle and cardiovascular function, and is involved in enzymatic and neurotransmitter processes. Calcium deficiency is widespread and associated with the development of osteoporosis and other metabolic disorders. The administration of medicinal preparations with calcium compensates its deficiency in patients and contribute to disease prevention and treatment. In the context of sustainable development, there is growing interest in new technologies for isolating organic calcium salts from marine bioresources for medicinal use. Aim. To develop and compare technologies for extraction of organic calcium from the shells of Arctic shrimp Pandalus borealis (a waste of food industry), and to evaluate the composition and purity of the obtained products. Materials and methods. The shells of cooked-frozen Arctic shrimps Pandalus borealis were processed by two calcium extraction technologies: (1) direct demineralization with organic acids (citric, malic and lactic) and (2) preliminary defatting of the raw material with ethanol followed by demineralization. Quantitative analysis of calcium (Ca) and other elements was performed by Inductively Coupled Plasma Optical Emission Spectroscopy (ICP-OES). A hazard quotient (HQ) was calculated for safety assessments. Results and discussion. It was found that the maximum calcium yield was achieved after demineralization with citric acid (153.0 ± 10.3 mg Ca/g). Malic and lactic acids showed less efficiency. Preliminary defatting reduced the Ca yield by an average of 2.2 %; however, the lipid fraction is of interest as a source of carotenoids and other natural lipids. Toxic elements (Pb, Cd, Ni, Cr, As) were either not detected or their concentrations were below the limit of quantification. The content of associated elements (Mg, Zn, Fe, Cu, and Mn) was below the toxic level (calculated HQ < 1). Consumption of isolated Ca products will provide enrichment of the dietary intake with certain microelements. Conclusion. The shells of Arctic shrimps are a valuable source of organic calcium for the environmentally friendly production of physiologically balanced calcium salts – calcium citrate, malate, and lactate. The resulting calcium salts are not polluted with toxic elements and can be used in the pharmaceutical and food industries.