Combination of a deep eutectic solvent and macroporous resin for green recovery of anthocyanins from Nitraria tangutorun Bobr. fruit

Metabolomic approaches to explore chemodiversity in seeds of guaraná (Paullinia cupana) using UPLC-QTOF-MSE and NMR analysis

The growing interest in health and well-being has spurred the evolution of functional foods, which provide enhanced health benefits beyond basic nutrition. Guaraná seeds (Paullinia cupana) have been widely studied and used as a functional food due to their richness in caffeine, phenolic compounds, amino acids, and other nutrients. This has established guaraná as a significant food supplement, with Brazil being the largest producer of the world. This study aims to propose a set of analytical methods to chemically evaluate fifty-six different guaraná clones, from the Guaraná Germplasm Active Bank, to accommodate the diverse requirements of the food industry. Metabolomic approaches were employed, in which a non-target metabolomic analysis via UPLC-QTOF-MSE led to the annotation of nineteen specialized metabolites. Furthermore, targeted metabolomics was also used, leading to the identification and quantification of metabolites by NMR. The extensive data generated were subjected to multivariate analysis, elucidating the similarities and differences between the evaluated guaraná seeds, particularly concerning the varying concentration levels of the metabolites. The metabolomics approach based on the combination of UPLC-QTOF-MSE, NMR and chemometric tools provided sensitivity, precision and accuracy to establish the chemical profiles of guaraná seeds. In conclusion, evaluating and determining the metabolic specificities of different guarana clones allow for their application in the development of products with different levels of specific metabolites, such as caffeine. This caters to various purposes within the food industry. Moreover, the recognized pharmacological properties of the annotated specialized metabolites affirm the use of guarana clones as an excellent nutritional source.

Efficient Extraction of Flavonoids from Lotus Leaves by Ultrasonic-Assisted Deep Eutectic Solvent Extraction and Its Evaluation on Antioxidant Activities

The discovery of a green extraction solvent for natural plants could promote related research. In this study, deep eutectic solvents (DES) were used as green solvents coupled with an ultrasound-assisted extraction method (UAE) to extract flavonoids from lotus leaves. Thirty-four different DES were performed and choline chloride/urea with 40% water was chosen as the most promising one, and the related parameters in the procedures were optimized, resulting in the highest extraction amount of flavonoids in lotus leaves. D-101 was selected from four macroporous resins to separate the flavonoids from DES. Moreover, DES could be recycled and efficiently reused four times with satisfactory performances. In addition, the lotus leaf flavonoids from the DES extract exhibited antioxidant activities in five kinds of assays including DPPH, ABTS, Fe3+ reducing, FRAP, and Fe2+ chelating. It also showed antibacterial activities on Staphylococcus aureus and Escherichia coli bacterial strains with minimal inhibitory concentrations at 1666 μg/mL and 208 μg/mL, respectively. In the HPLC analysis, the three main components in the DES extract were identified as astragalin, hyperoside, and isoquercitrin. In conclusion, the developed UAE-DES followed by macroporous resin treatment could become an efficient and environmentally friendly extraction and enrichment method for flavonoids from lotus leaves and other natural products.

Current Progress in Natural Deep Eutectic Solvents for the Extraction of Active Components from Plants

In the last decade, natural deep eutectic solvents (NADESs) have gained more and more attention due to their green, convenient preparation, low toxicity and biodegradability. It is widely used in various fields, especially in the extraction of active components from plants, formed by the combination of hydrogen bond donors (HBDs) and hydrogen bond acceptors (HBAs) at a certain condition. In this article, six preparation methods of NADESs were summarized and the interactions that occur in the eutectic behavior of NADES including hydrogen bonding, electrostatic interaction and van der Waals force were also reviewed. What is more, its significant extraction capacity on flavonoids, phenols, alkaloids and plant pigments endows its extensive applications in the extraction of active components from medicinal plants. Extraction factors including solvents properties (viscosity, carbon chain length, number of hydroxyl groups), extraction condition (water content, extraction temperature, extraction time, solid-liquid ratio), extraction method and recycling method were discussed. In addition, NADESs can also be combined with other technologies, like molecular imprinting, monolithic column, to achieve efficient and specific extraction of active ingredients. Further systematic studies on the biodegradability and biotoxicity are put forward to be urgent.