Use Of Deep Eutectic Solvents Research Articles

Development of a Ready-to-Use Oxyresveratrol-Enriched Extract from Artocarpus lakoocha Roxb. Using Greener Solvents and Deep Eutectic Solvents for a Whitening Agent

Oxyresveratrol (ORV) is naturally found in Artocapus lakoocha Roxb. (AL), similar to resveratrol. This AL extract has demonstrated considerable importance in dietary supplements and cosmetics for its anti-tyrosinase and antioxidant properties. There is a great demand for ORV in the cosmetic and pharmaceutical industries. Traditionally, harsh solvents have been used to extract ORV from AL. This study aims to address this issue by introducing green technology with a ready-to-use extract for the enrichment of ORV extraction from AL using deep eutectic solvents (DESs). Thirty-three DESs were synthesized and characterized. The extraction efficiency of these DESs was evaluated by ORV content (g ORV/kg dried plant) and compared with the conventional solvents, analyzed by validated HPLC. Notably, two synthesized DESs, namely choline chloride/citric acid/water (2:1:3) (DES10) and choline chloride/xylose (1:1) (DES17), showed higher ORV content than the conventional solvents and were therefore selected for optimization of extraction conditions using Box–Behnken designs, considering three variable levels: time, temperature, and water as co-solvents. Interestingly, the biological activities of ORV-enriched extracts from DES10 and DES17 were evaluated, and the results showed that they were 74-fold and 252-fold more potent than kojic acid in terms of tyrosinase inhibitory activity. DES17 was 17- fold more potent antioxidants than ascorbic acid. The morphology of AL powder before and after extraction with DESs under SEM suggested that DESs have the same mechanism as classical organic solvents. These ORV-enriched extracts can be directly incorporated into cosmetic formulations and production scales without the need to prepare a stock solution and are therefore referred to as ready-to-use extracts. This study successfully pioneered the use of DESs for environmentally friendly and highly efficient ORV extraction from AL to produce ready-to-use extracts and applications for the pharmaceutical and cosmetic industries.

A Review on the Use of Deep Eutectic Solvents in Protection Reactions.

Given the recent research on the application of eco-sustainable methods in organic chemistry, we have focused our attention on the derivatization processes for fundamental functional groups in organic chemistry, such as amino, hydroxyl and carbonyl groups. Protection reactions are needed to temporarily block a certain reactive site on a molecule. The use of green solvents in this context has made an excellent contribution to the development of eco-sustainable methods. In recent years, deep eutectic solvents (DESs) have had great success as a new class of green solvents used in various chemical applications, such as extraction or synthetic processes. These solvents are biodegradable and nontoxic. In this framework, a list of relevant works found in the literature is described, considering DESs to be a good alternative to classic toxic solvents in the protection reactions of important functional groups.

Role of Ionic Solvents in the Electrocatalytic CO2 Conversion and H2 Evolution Suppression: from Ionic Liquids to Deep Eutectic Solvents

AbstractThe ionic solvents, including both ionic liquids (ILs) and deep eutectic solvents (DES), are deeply studied for their potential in the carbon dioxide (CO2) capture and its further electrochemical conversion using different electrocatalysts. The aim of this review is to present and critically compare the role of ILs and DES in the activation of the electrochemical CO2 reduction reaction (CO2RR) and suppression of the hydrogen evolution reaction (HER). Therefore, the most relevant advances in the use of these ionic solvents in CO2RR, either as neat reaction medium or as electrolyte in molecular solvents, have been summarized and discussed. A special focus has been made on comparing the current density, overpotential, faradaic efficiency and products selectivity of the CO2RR in the presence of the ionic solvents and relaying those results with their chemical composition. Herein, the most recent strategies reported in the literature based on the use of either DES or ILs for enhancing the electrocatalytic CO2 conversion are reviewed, and some new perspectives based on immobilized ILs at the electrode surface are discussed.

Evaluation of deep eutectic solvents chiral selectors based on lactobionic acid in capillary electrophoresis.

Recently, deep eutectic solvents (DESs) have attracted considerable interest in analytical chemistry. This work described the enantioseparations of twenty amino alcohol drugs with several DESs based on lactobionic acid (LA) as the sole chiral selector in capillary electrophoresis (CE) firstly. Compared to the single LA system and the ionic liquid/LA synergistic system, the DES system exhibited considerably improved separations. The influences of some key parameters on separations were investigated in detail. This work also experimentally demonstrated that the carboxyl group was indispensable in the process of chiral recognition. The mechanisms of the improvements of DESs on enantioseparations were studied via ultraviolet spectroscopy. Furthermore, the proposed method was used to determine the enantiomeric purity of propranolol hydrochloride successfully. This is the first time that chiral DESs were utilized as the sole chiral selectors in CE, and this strategy has opened up a new prospect for the use of DESs in enantioseparation.

The use of deep eutectic solvents as a promising approach in the design of microwave-based green gas sensors

Highlighting the use of deep eutectic solvent (DES) as the sensitive material of a new sustainable microwave gas sensor through the development of a simple and low-cost device sensitive to hydrogen chloride.

Porous phenolic resin regulated by alcohol-based deep eutectic solvent for selective extraction and separation of tanshinones from Salvia miltiorrhiza

Deep eutectic solvents (DES), regarded as promising green solvents, have gained attention due to their distinctive properties, particularly in analytical chemistry. While the use of DES in solvent extraction and separation has been extensively studied, its application in the synthesis of adsorbents has just begun. Phenolic resin, with its polyhydroxy structure and stable spherical morphology, could serve as an effective as adsorbents for enrichment of active ingredients in herbal medicine. Designing adsorbents with high selectivity and adsorption capacity presents a critical challenge in the enrichment of active ingredients in herbal medicine. In this study, alcohol-based DESs were employed as regulators of morphology and structure instead of organic solvents, facilitating the creation of polyhydroxy structure, adjustable pores and high specific surface areas. The resulting DES-regulated porous phenolic resin demonstrated enhanced extraction and separation capacity for active ingredients compared to conventional spherical phenolic resin owing to the alcohol-based DES offering more interaction modes with the analytes.

Valorization of brewer's yeast using Deep Eutectic Solvents pretreatment for fractionation and separation of cell wall polysaccharides

Beer yeast is an excellent source of β-glucans or mono-and oligosaccharides, which have various biological and technical functional properties and can be used as food ingredients. The steps involved in extracting β-glucan from beer yeast cells, such as cell wall disruption and purification, have notable effects on the compound's yield, cost, and various properties, including biological, physicochemical, and technical aspects. In this study, by comparing the extraction efficiencies of 6 synthetic deep eutectic solvents (DESs) for β-glucan in brewer's yeast, it was found that using DES composed of choline chloride and lactic acid resulting in the yield and purity of insoluble β-glucan (IBG) was 1.30 g/g and 49.3%. Even after one cycle of DES, IBG could still be separated with a yield of 0.26 g/g and a purity of 39.1%. Additionaly, the molecular weight of IBG separated by the DES method was 1.0–1.6 kDa, significantly lower than the range obtained using the traditional alkali-alcohol separation method (39.8–656 kDa). The results suggest an alternative use of DES for spent beer yeast byproduct extraction.

Exploring the potential of deep eutectic solvents (DES) in bioactive natural product research: from DES to NaDES, THEDES, and beyond

Background Deep eutectic solvents (DESs) have garnered significant interest in natural products research, owing to their green and natural attributes in comparison to conventional solvents. However, the approach of demonstrating that DESs are superior extractants has led to an underestimation of their full potential in this field. This perspective disregards crucial challenges related to their practical application and potential scalability, mainly the difficulty of target component separation from intermolecular network forming by DESs. Conversely, the DESs unique features can enhance aspects such as solubilization, stabilization, and storage of natural products, as well as improve their biological activities. By addressing key challenges and limitations, we aim to provide valuable insights into the potential of DESs in this domain. Methodology In this review, we conducted an exhaustive literature search to gather relevant articles about DESs and their applications in bioactive natural product research. The gathered literature was analyzed, and a systematic thematic categorization was performed, emphasizing studies where the use of DESs yielded relevant outcomes that could potentially present an advantage in the exploration of bioactive natural products. The approach in structuring this review aimed to provide an overview of the potential and challenges associated with DESs in the domain of bioactive natural product research, transcending their conventional role as mere extraction solvents. Results Through this critical analysis of the literature, this review delves into the potential of DESs as effective solvents for the solubilization, stabilization, and storage of bioactive natural products. In addition, it highlights the ability of DESs to improve the biological activities of natural products, as well as to be used as formulation media for the transport of pharmaceutical active ingredients. By revealing these advances, the review contributes to a more complete understanding of DESs and its applicability in the field of bioactive natural products research. Conclusions The studies compiled in this review underscore the expanded potential of DESs, beyond extraction, finding relevance in the realm of natural products research. Notably, they contribute to enhancing the desired attributes of the final product, signifying a promising avenue for future advancements in this field.

Deep eutectic solvents as a green alternative for trace element analysis in food and beverage samples: Recent advances and challenges

Metals and metalloids have different effects on human health even at trace levels. Some of them are essential for living organisms while others can be toxic. Therefore, the determination of trace elements in food and beverage is highly important to understand their impact in human health. A new generation of solvents named deep eutectic solvents (DES) has emerged as a green alternative for trace element analysis, owing to their low toxicity, biodegradability, and high extraction capacity. In recent years, the application of DES in extraction techniques for trace element analysis in food and beverage samples has increased significantly. This review summarizes recent advances and challenges on the application of DES to develop microextraction techniques useful for the analysis of samples with complex matrices. The importance of the use of biodegradable substances instead of classic organic solvents, which are toxic, volatile, and flammable in methods for elemental analysis with a positive environmental impact is also highlighted. Finally, conclusions and future challenges arising from the use of DES in microextraction techniques are discussed.

Green extraction of phenolics using deep eutectic solvents: a promising neoteric method

There has been a growing emphasis on developing extraction methods that are not only efficient but also environmentally friendly and sustainable. One promising avenue is the exploration of deep eutectic solvents (DESs) as neoteric extraction media. This study aims to investigate the potential of DESs as neoteric extraction media for phenolics-rich flower clove extracts. Two DESs were synthesised by mixing choline chloride with glycerol and lactic acid at a molar ratio of 1:2. The thermal profiles of the mixture were analysed using differential scanning calorimetry, and the viscosity and density were measured at different temperatures. The phenolic compounds were quantitatively characterised for all of the extractants using high-performance liquid chromatography. The total phenolic content and the antioxidant activities of the extracts were determined. The results showed that DESs significantly improved the extraction of antioxidant compounds from clove, especially for the case of phenolic compounds, and also considerably enhanced the antioxidant activity of the extracts. The use of DESs offers a green, efficient method for extracting value-added products from natural sources.

Screening deep eutectic solvents as green extractants for oil from plant seeds based on COSMO-RS model

Deep eutectic solvents (DESs) have recently attracted considerable interest as eco-friendly alternatives for conventional solvents in many industrial separation processes. However, due to its vast number of possible combinations, reliable approaches for guiding the selection of task-specific DES remain limited. Using conductor-like screening model for real solvent (COSMO-RS), the solubility capacity was applied to screen 126 deep eutectic solvents to estimate their potential use as plant seed oil extractants. Moreover, DESs’ σ-profiles were matched to σ-profiles of linoleic acid and glutamine, representing oil and oil protective protein membrane, to evaluate their molecule interactions. Results of COSMO-RS revealed that the DESs with higher linoleic acid solubility capacity showed lower solubility capacity for protein and vice versa. Moreover, σ-profiles of representative DESs demonstrated this behavior by comparing the similarity of DESs to both linoleic acid and protein. Consequently, DESs with high linoleic acid solubility could be used as individual solvents, while DESs with high protein solubility could be used as co-solvents with organic solvents. However, the experimental results proved that the use of DESs having high protein capacity, as co-solvents with diethyl ether, n-pentane and n-heptane raised the extracted oil yield. Utilizing ChCl:Gly (1:2) as a co-solvent with diethyl ether produced the highest yield of 30.7% compared to pure diethyl ether, which produced 27.0%.

Deep eutectic solvents for the determination of endocrine disrupting chemicals

The harmful effects of endocrine disrupting chemicals (EDCs) to humans and other organisms in the environment have been well established over the years, and more studies are ongoing to classify other chemicals that have the potential to alter or disrupt the regular function of the endocrine system. In addition to toxicological studies, analytical detection systems are progressively being improved to facilitate accurate determination of EDCs in biological, environmental and food samples. Recent microextraction methods have focused on the use of green chemicals that are safe for analytical applications, and present very low or no toxicity upon disposal. Deep eutectic solvents (DESs) have emerged as one of the viable alternatives to the conventional hazardous solvents, and their unique properties make them very useful in different applications. Notably, the use of renewable sources to prepare DESs leads to highly biodegradable products that mitigate negative ecological impacts. This review presents an overview of both organic and inorganic EDCs and their ramifications on human health. It also presents the fundamental principles of liquid phase and solid phase microextraction methods, and gives a comprehensive account of the use of DESs for the determination of EDCs in various samples.

An acid-based DES as a novel catalyst for the synthesis of pyranopyrimidines

Deep eutectic solvents have countless advantages over normal solvents, and in addition to complying with the principles of green chemistry, depending on their nature, they can also act as catalysts. The use of deep eutectic solvents as acid catalysts has several advantages such as non-toxicity, a catalytic effect similar to or higher than the acid itself, and the possibility of recovery and reuse without significant loss of activity. In this project, A novel deep eutectic solvent (MTPPBr–PCAT–DES) was prepared from a one-to-one mole ratio of methyltriphenyl-phosphonium bromide (MTPPBr) and 3,4-dihydroxybenzoic acid (PCAT = protocatechuic acid) and characterized by various techniques such as FT-IR, TGA/DTA, densitometer, eutectic point, 1H NMR, 13C NMR and 31P NMR. Then, it was used as a novel and capable catalyst for the synthesis of pyranopyrimidines from the multicomponent condensation reaction of barbituric acid, 4-hydroxycoumarin, and aromatic aldehydes in mild conditions, short reaction times, and high yields.

Menthol-Based (Deep) Eutectic Solvents: A Review on Properties and Application in Extraction.

In the last 10 years the interest in deep eutectic solvents (DESs) as a new class of green solvents has considerably increased. The emergence of numerous of hydrophobic DESs has stimulated intensive research into their application in extraction technologies, including sample preparation. As the properties of such systems are highly dependent on the properties of their components (hydrogen bond donors and acceptors) and can be finely tuned, DESs can be successfully used for the extraction of both metal ions and organic substances, including biomolecules. Despite the rapidly increasing number of publications on the use of DESs as an extraction medium, including review articles, information on the extraction properties of DESs in terms of their chemical composition has not yet been summarized. This review covers available literature data on the physicochemical properties of menthol-based eutectic solvents and the results of their practical application as an extraction medium. Also, the appropriateness of using the term "DES" for all mixtures with melting points lower than the melting points of their components is discussed.

Malic acid-based deep eutectic solvent and its application in Insulin's structural stability

Deep eutectic solvents (DESs) and Ionic Liquids (ILs) have been recently used as a solvent for insulin delivery via subcutaneous, transdermal, oral, and nasal ways. However, due to their high viscosity, DESs are usually impractical for delivery applications in their pure solution. The addition of water decreases the viscosity of DESs, but it can also influence the structural stability of the proteins. Hence, DES-water solutions and their effect on insulin's structural stability need to be investigated. In this study, molecular dynamics simulations on insulin dimer in DES consisting of malic acid and choline chloride (MA-ChCl) with varying amounts of water were performed. Insulin is strongly stabilized in the DES and its aqueous solutions as compared to water. However, in the DES solutions with 50 % and 75 % water content, malic acid was observed to interact readily with insulin dimer and its binding site, causing the separation of the two monomers. Therefore, while the insulin dimer is stable in the DES with low water content, in the presence of higher amounts of water it is destabilized and the monomers are separated. Considering that insulin's active form is monomeric, and the decomposition of insulin into monomers before reaching the bloodstream can increase the pharmacokinetics of insulin delivery, the use of the aqueous DES for rapid insulin delivery is highly relevant.

Synthesis of Imidazole-Based Deep Eutectic Solvents as Solid Lubricants: Lubricated State Transition.

The controllable character of the melting point of deep eutectic solvents (DESs) makes it easy to realize lubricated state transitions and produce excellent lubricating properties during friction. In this work, a series of novel imidazole-based DESs were synthesized to present a room-temperature solid state by shifting its eutectic point. Tribological test results show that the wear volume of these DESs decreases as the alkyl chains of the hydrogen bond donors increase. A proper deviation of the eutectic point in DESs produces stable lubricating properties. The present work provides a novel and simple method to prepare solid lubricants and enriches the use of DESs as lubricants. Simultaneously, the method expected to replace the use of conventional cutting fluids.

Construction of ternary PEG200-based DESs lubrication systems via tailoring tribo-chemistry

Designing novel lubricants with easily customized structures, devisable compositions, and simple and economic synthesis over traditional lubricants is critical to fulfilling complex applications, prolonging machine lifetime, and saving energy. Deep eutectic solvents (DESs), which show tunable composition, adjustable structure, easy fabrication, and environmental friendliness, are promising candidates for variable and complicated lubricants applications. To promote the use of DESs as lubricants, a series of PEG200-based DESs with active heteroatoms were fabricated to tailor the tribological performance via tribo-chemistry. Thereinto, PEG200/boric acid (BA) DES shows optimal lubrication performance by forming tribo-chemical reaction film composited of B2O3, iron oxides, and FeOOH, and PEG200/thiourea (TU) DES displays abrasive wear-reducing property by producing FeS tribo-chemical film. Given the excellent abrasive wear-resistance of PEG200/TU DES and friction reduction of PEG200/BA DES, ternary PEG200/BA/TU DESs, composited of PEG200/TU DES and PEG200/BA DES, are first exploited. The ternary DESs possess superior wettability and thermal stability, which render them potential lubricants. Tribological tests of the ternary DESs demonstrate that synergistic lubrication is achieved by forming a transfer film consisting of FexBy, BN, B2O3, and FeS. Wherein FexBy, BN, and B2O3 increase load bearing of the film, and FeS mitigates severe abrasive wear. The proposed design philosophy of novel DESs as lubricants opens up a unique realm that is unattainable by traditional DESs lubrication mechanisms and provides a platform to design next-generation DESs lubrication systems.

Deep eutectic solvents in sample preparation and determination methods of pesticides: Recent advances and future prospects

This review summarizes recent advances of deep eutectic solvents (DESs) in sample preparation and determination methods of pesticides in food, environmental, and biological matrices since 2019. Emphasis is placed on new DES categories and emerging microextraction techniques. The former incorporate hydrophobic deep eutectic solvents, magnetic deep eutectic solvents, and responsive switchable deep eutectic solvents, while the latter mainly include dispersive liquid-liquid microextraction, liquid-liquid microextraction based on in-situ formation/decomposition of DESs, single drop microextraction, hollow fiber-liquid phase microextraction, and solid-phase microextraction. The principles, applications, advantages, and limitations of these microextraction techniques are presented. Besides, the use of DESs in chromatographic separation, electrochemical biosensors, fluorescent sensors, and surface-enhanced Raman spectroscopy are discussed. This review is expected to provide a valuable reference for extracting and detecting pesticides or other hazardous contaminants in the future.

Upcycling Wool Waste into Keratin Gel-Based Nanofibers Using Deep Eutectic Solvents.

Millions of tons of wool waste are produced yearly by textile industries, which may become a serious environmental hazard in the near future. Given this concern, it is crucial to explore strategies to reduce the amount of wool waste generated worldwide and adopt more sustainable practices for dissolving and regenerating wool keratin (WK) from textile waste. Most traditional methods involve the use of expensive, toxic, harmful, and poorly biodegradable compounds. To overcome these limitations and facilitate the reuse of wool waste through a cascade valorization strategy, researchers have started testing the use of deep eutectic solvents (DES) as a more sustainable and eco-friendly alternative for WK dissolution and regeneration. In this study, the potential of two different DES mixtures, Choline chloride (ChCl): Urea and L-Cysteine (L-Cys): Lactic acid (LA), was explored for dissolving wool waste. Subsequently, the gels obtained based on DES-WK were blended with polyvinyl alcohol (PVA) in different ratios to produce nanofibers using the electrospinning technique. The PVA/L-Cys: LA DES-WK proved to be the most effective DES mixture for fabricating WK gel-based nanofibers. Furthermore, their antioxidant and antimicrobial abilities were evaluated, thus confirming their bioactivity. The results obtained revealed that this approach to valorizing textile waste offers a unique avenue for the development of sustainable functional materials with potential applications in various biomedical and industrial fields.

Efficient Conversion of Monosaccharides into 5-Hydroxymethylfurfural Using Acidic Deep Eutectic Solvents

In this study, a quick, simple, green method of converting carbohydrates into 5-hydroxymethylfurfural (HMF) with the use of deep eutectic solvents (DESs) was reported on. We synthesized 12 DESs for HMF conversion from carbohydrates which were studied under different conditions. Under optimal conditions, oxalic acid and citric acid with a choline chloride-based DES produced a maximum yield of HMF at 59 ± 2% and 62 ± 3% in 5 min at 120 °C, respectively. The efficiency of converting glucose to HMF in a short time (5 min) at 140 °C using CrCl3 with a choline chloride-based DES was around 37 ± 1%, which was higher than in previous work. This study demonstrates the significant potential of DESs as a combination for the continuous catalytic transformation of biomass in the synthesis of platform chemicals.