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.

Phaeophyceae (brown algae) essentially contribute to biotopes of cold and temperate seas. Their thalli are rich in biologically active natural products, which are strongly and universally dominated with phlorotannins—polyphenols of complex and diverse structure based on multiple differently arranged phloroglucinol units and well known as strong antioxidants with a broad spectrum of biological activities. In the algal cells, phlorotannins can either accumulate in the cytoplasm or can be secreted into the cell wall (CW). The biological activities of extractable intracellular phlorotannins have been comprehensively characterized, whereas the properties of the CW-bound polyphenol fraction are still mostly unknown. Recently, we identified dibenzodioxin bonding as the principal structural feature of the CW-bound phlorotannins in fucoid algae, whereas soluble intracellular phlorotannins rely on aryl and ether bonds. However, profiles of biological activity associated with these structural differences are still unknown. Therefore, to the best of our knowledge, for the first time we address the antioxidant, cytotoxic, neuroprotective, and antibacterial properties of the CW-bound phlorotannin fractions isolated from two representatives of the order Fucales—Fucus vesiculosus and Pelvetia canaliculata. The CW-bound phlorotannins appeared to be softer antioxidants, stronger antibacterial agents and were featured with essentially less cytotoxicity in comparison to the intracellular fraction. However, the neuroprotective effects of both sub-cellular phlorotannin fractions of F. vesiculosus and P. canaliculata were similar. Thus, due to their lower cytotoxicity, CW-bound phlorotannins can be considered as promising antioxidants and neuroprotectors.

Metabolomics, which is typically referred to as the post-genomic methodology addressing low-molecular-weight metabolites, became a powerful tool in post-genomic research over the last two decades. Indeed, the state-of-the-art metabolomics relies on several well-established complementary platforms—nuclear magnetic resonance (NMR) spectroscopy, liquid and gas chromatography coupled on-line with mass spectrometry (LC- and GC-MS, respectively), and capillary electrophoresis–mass spectrometry (CE-MS). Among them, GC-MS represents one of the oldest and most well-established techniques currently employed in the metabolomics of volatile compounds and non-volatiles—polar low-molecular-weight metabolites, which can be efficiently converted in volatile form by comprehensive derivatization of polar functional groups. Currently, GC-MS is established as the principal analytical method for characterizing primary plant metabolism, although other methods also contribute significantly to determining the complete metabolite profile. Therefore, here, we address the role of GC-MS in plant metabolomics and its potential for the profiling of low-molecular-weight metabolites. Further, we comprehensively review the methods of sample preparation with special emphasis on extraction and derivatization approaches, which are currently employed to improve the method performance and its metabolome coverage.

Maintaining quality of life with an increase in life expectancy is considered one of the global problems of our time. This review explores the possibility of using natural plant compounds with antioxidant, anti-inflammatory, anti-glycation, and anti-neurodegenerative properties to slow down the onset of age-related changes. Age-related changes such as a decrease in mental abilities, the development of inflammatory processes, and increased risk of developing type 2 diabetes have a significant impact on maintaining quality of life. Herbal preparations can play an essential role in preventing and treating neurodegenerative diseases that accompany age-related changes, including Alzheimer’s and Parkinson’s diseases. Medicinal plants have known sedative, muscle relaxant, neuroprotective, nootropic, and antiparkinsonian properties. The secondary metabolites, mainly polyphenolic compounds, are valuable substances for the development of new anti-inflammatory and hypoglycemic agents. Understanding how mixtures of plants and their biologically active substances work together to achieve a specific biological effect can help develop targeted drugs to prevent diseases associated with aging and age-related changes. Understanding the mechanisms of the biological activity of plant complexes and mixtures determines the prospects for using metabolomic and biochemical methods to prolong active longevity.

The main role of RALF small signaling peptides was reported to be the alkalization control of the apoplast for improvement of nutrient absorption; however, the exact function of individual RALF peptides such as RALF34 remains unknown. The Arabidopsis RALF34 (AtRALF34) peptide was proposed to be part of the gene regulatory network of lateral root initiation. Cucumber is an excellent model for studying a special form of lateral root initiation taking place in the meristem of the parental root. We attempted to elucidate the role of the regulatory pathway in which RALF34 is a participant using cucumber transgenic hairy roots overexpressing CsRALF34 for comprehensive, integrated metabolomics and proteomics studies, focusing on the analysis of stress response markers. CsRALF34 overexpression resulted in the inhibition of root growth and regulation of cell proliferation, specifically in blocking the G2/M transition in cucumber roots. Based on these results, we propose that CsRALF34 is not part of the gene regulatory networks involved in the early steps of lateral root initiation. Instead, we suggest that CsRALF34 modulates ROS homeostasis and triggers the controlled production of hydroxyl radicals in root cells, possibly associated with intracellular signal transduction. Altogether, our results support the role of RALF peptides as ROS regulators.

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.