Deep Eutectic Solvents as Novel and Effective Extraction Media for Quantitative Determination of Ochratoxin A in Wheat and Derived Products

Green and efficient extraction of phenolic compounds from Neem leaves using deep eutectic solvents based ultrasonic-assisted extraction

Deep eutectic solvent (DES) combined with ultrasonic-assisted extraction was employed as an environmentally friendly technique for extracting antioxidant phenolic compounds from Neem leaves in place of organic solvents. Choline chloride-Ethylene glycol (1:2) with 40% V/V water content (DES-1) was investigated as a potential total phenolic content extractant (38.2 ± 1.2 mg GAE/g DW, where GAE: gallic acid equivalent, DW: dry weight). The optimal operational parameters assessed using single-factor experiments to maximize the total phenolic compounds content were as follows: extraction time of 30 min, 40% V/V water content, liquid-solid ratio of 15:1, and room temperature. Additionally, the in-vitro antioxidant experiments (2,2-diphenyl-1- picrylhydrazyl radical scavenging assay and ferric reducing antioxidant power assay) demonstrated the DES-1-based extract of Neem leaves as a potent antioxidant agent, compared to traditional solvents. Moreover, microscopic morphological analysis supported the effectiveness of DES-1 for the noticeable alteration in the fiber surface structure of Neem leaves after extraction which benefited in the release of polyphenols from these leaves. Eventually, the mass analysis of the extract disclosed the presence of eleven polyphenols in the extract. The Green Analytical Procedure Index revealed the greenness of the extraction method.

Deep eutectic solvents: Preparation, properties, and food applications

Deep Eutectic Solvents (DESs) emerge as innovative 21st-century solvents, supplanting traditional ones like ethanol and n-hexane. Renowned for their non-toxic, biodegradable, and water-miscible nature with reduced volatility, DESs are mostly synthesized through heating and stirring method. Physicochemical properties such as polarity, viscosity, density and surface tension of DESs influenced their application. This review paper gives the overview of application of eco-benign DESs in fruits, vegetables, cereals, pulses, spices, herbs, plantation crops, oil seed crops, medicinal and aromatic plants, seaweed, and milk for the extraction of bioactive compounds. Also, it gives insight of determination of pesticides, insecticides, hazardous and toxic compounds, removal of heavy metals, detection of illegal milk additive, purification of antibiotics and preparation of packaging film. Methodologies for separating bioactive compounds from DESs extracts are systematically examined. Further, safety regulations of DESs are briefly discussed and reviewed literature reveals prevalent utilization of DES-based bioactive compound rich extracts in cosmetics, indicating untapped potential of their application in the food industry.

Extracting mycotoxins from edible vegetable oils by using green, ecofriendly deep eutectic solvents

In this work, we developed an environmentally friendly liquid-liquid microextraction method using a natural deep eutectic solvent in combination with liquid chromatography for the simultaneous determination of four mycotoxins (deoxynivalenol, alternariol, ochratoxin A and zearalenone) in edible vegetable oils. A chemometric approach assessed the effect of the operational parameters on the mycotoxin extraction efficiency. The extracts were analyzed by HPLC coupled with a diode array and fluorescence detector. The optimum NADES composition resulted in the highest extraction recoveries, and it was applied to coextract the target mycotoxins in several types of edible vegetable oils without using hazardous solvents or requiring further clean-up. The limits of detection ranged from 0.07 to 300 µg kg-1, and recoveries were close to 100%, except for zearalenone (viz. 35%), with relative standard deviations below 9% in all cases. The proposed method was validated following the European Commission 2002/657/EC and 2006/401/EC.

A New Inert Natural Deep Eutectic Solvent (NADES) as a Reaction Medium for Food-Grade Maillard-Type Model Reactions

Sustainability, low toxicity, and high solute potential are the fundamental reasons for focusing green chemistry on natural deep eutectic solvents (NADES). The application of NADES ranges from organic chemistry to the agricultural sector and the food industry. In the food industry, the desired food quality can be achieved by the extraction of small molecules, macromolecules, and even heavy metals. The compound yield in Maillard-type model reactions can also be increased using NADES. To extend the so-called "kitchen-type chemistry" field, an inert, food-grade NADES system based on sucrose/D-sorbitol was developed, characterized, and examined for its ability as a reaction medium by evaluating its temperature and pH stability. Reaction boundary conditions were determined at 100 °C for three hours with a pH range of 3.7-9.0. As proof of principle, two Maillard-type model reactions were implemented to generate the taste-modulating compounds N²-(1-carboxyethyl)guanosine 5'-monophosphate) (161.8 µmol/mmol) and N²-(furfuryl thiomethyl)guanosine 5'-monophosphate (95.7 µmol/g). Since the yields of both compounds are higher than their respective taste-modulating thresholds, the newly developed NADES is well-suited for these types of "kitchen-type chemistry" and, therefore, a potential solvent candidate for a wide range of applications in the food industry.

Menthol and Fatty Acid-Based Hydrophobic Deep Eutectic Solvents as Media for Enzyme Activation

This research aims to provide insights into the biological efficacy of a newly formed hydrophobic deep eutectic solvent (DES). A DES based on menthol was successfully synthesized with fatty acids. The DESs’ properties as enzyme activators were examined against a neat counterpart. The menthol:decanoic acid (1:1) combination showed improved thermal stability, strong catalytic activity, and reusability for up to four subsequent cycles under ideal conditions (pH 7.0, 40 °C for 2 h). The hydrophobic DES replaced hexane in ester synthesis, where RNL@DES5 showed better fatty acid conversion compared to neat RNL. This study demonstrated promising applications of hydrophobic DESs in non-aqueous organic reactions.

Research Progress on the Preparation and Action Mechanism of Natural Deep Eutectic Solvents and Their Application in Food

Natural deep eutectic solvent (NADES) is the eutectic mixture which is formed by hydrogen bond donors (HBDs) and hydrogen bond acceptors (HBAs) with a certain molar ratio through hydrogen bonding. NADES is a liquid with low cost, easy preparation, biodegradability, sustainability and environmental friendliness at room temperature. At present, it is widely used in food, medicine and other areas. First, the composition, preparation and properties of NADES are outlined. Second, the potential mechanism of NADES in freezing preservation, the removal of heavy metals from food and the extraction of phenolic compounds, and its application in cryopreservation, food analysis and food component extraction, and as a food taste enhancer and food film, are summarized. Lastly, the potential and challenges of its application in the food field are reviewed. This review could provide a theoretical basis for the wide application of NADES in food processing and production.

Food Industry Byproducts as Starting Material for Innovative, Green Feed Formulation: A Sustainable Alternative for Poultry Feeding

Rising global populations and enhanced standards of living in so-called developing countries have led to an increased demand of food, in particular meat, worldwide. While increasing the production of broiler meat could be a potential solution to this problem, broiler meat is plagued by health concerns, such as the development of antimicrobial resistance and lower meat quality. For this reason, the supplementation of poultry feed with vitamins and antioxidant compounds, such as polyphenols, has become an attractive prospect for research in this sector. Such supplements could be obtained by extraction of agricultural byproducts (in particular, grape pomaces and artichoke leaves and bracts), thus contributing to reductions in the total amount of waste biomass produced by the agricultural industry. In this review, the effects of poultry feed supplementation with bioactive extracts from grape pomace (skins and/or seeds), as well as extracts from artichoke leaves and bracts, were explored. Moreover, the various methods that have been employed to obtain extracts from these and other agricultural byproducts were listed and described, with a particular focus on novel, eco-friendly extraction methods (using, for example, innovative and biocompatible solvents like Deep Eutectic Solvents (DESs)) that could reduce the costs and energy consumption of these procedures, with similar or higher yields compared to standard methods.

Deep Eutectic Solvents in Solar Energy Technologies

Deep Eutectic Solvents (DESs) have been widely used in many fields to exploit their ecofriendly characteristics, from green synthetic procedures to environmentally benign industrial methods. In contrast, their application in emerging solar technologies, where the abundant and clean solar energy is used to properly respond to most important societal needs, is still relatively scarce. This represents a strong limitation since many solar devices make use of polluting or toxic components, thus seriously hampering their eco-friendly nature. Herein, we review the literature, mainly published in the last few years, on the use of DESs in representative solar technologies, from solar plants to last generation photovoltaics, featuring not only their passive role as green solvents, but also their active behavior arising from their peculiar chemical nature. This collection highlights the increasing and valuable role played by DESs in solar technologies, in the fulfillment of green chemistry requirements and for performance enhancement, in particular in terms of long-term temporal stability.

Deep Eutectic Solvents Application in Food Analysis

Current trends in Analytical Chemistry are focused on the development of more sustainable and environmentally friendly procedures. However, and despite technological advances at the instrumental level having played a very important role in the greenness of the new methods, there is still work to be done regarding the sample preparation stage. In this sense, the implementation of new materials and solvents has been a great step towards the development of "greener" analytical methodologies. In particular, the application of deep eutectic solvents (DESs) has aroused great interest in recent years in this regard, as a consequence of their excellent physicochemical properties, general low toxicity, and high biodegradability if they are compared with classical organic solvents. Furthermore, the inclusion of DESs based on natural products (natural DESs, NADESs) has led to a notable increase in the popularity of this new generation of solvents in extraction techniques. This review article focuses on providing an overview of the applications and limitations of DESs in solvent-based extraction techniques for food analysis, paying especial attention to their hydrophobic or hydrophilic nature, which is one of the main factors affecting the extraction procedure, becoming even more important when such complex matrices are studied.

Mycotoxin extraction from edible insects with natural deep eutectic solvents: a green alternative to conventional methods

Edible insects are widely consumed in Africa, Asia, Oceania and Latin America, but less commonly so in Western countries. Since the turn of the millennium, however, entomophagy has aroused growing interest worldwide in response to the increasing scarcity of food resources. In fact, edible insects can be a source of high-quality protein, and also of fat, energy, minerals and vitamins. However, the lack of regulatory guidelines for microbiologically or chemically hazardous agents potentially present in these new foods (e.g., mycotoxins) may make their consumption unsafe. In this work, we developed an environmentally friendly analytical method using natural deep eutectic solvents (NADES or natural DES) in combination with ultra-high performance liquid chromatography/tandem mass spectrometry (UHPLC-MS/MS) for the simultaneous determination of six mycotoxins of great concern owing to their toxic effects on humans and animals (namely, fumonisin B₁, fumonisin B₂, T-2 toxin, HT-2 toxin, ochratoxin A and mycophenolic acid) in insect-based food products. The target mycotoxins were co-extracted from cricket flour by using the optimum DES composition (namely, a mixture of choline chloride and urea, in a 1:2 mole ratio, containing 15% water which resulted in the highest extraction recoveries for all toxins). An experimental design method (Fractional Factorial Design (FFD) was used to examine the influence of the operational variables DES volume and water content, amount of sample, extraction time and extraction temperature on the extraction efficiency for each mycotoxin. Under optimum conditions, extraction recoveries were close to 100% except for fumonisin B₂ (70%) and T-2 toxin (50%), with relative standard deviations (RSDs) below 13% in all cases. The proposed NADES-UHPLC-MS/MS method was validated in accordance with the European Commission 2002/657/EC and 2006/401/EC decisions, and used to determine the target compounds in cricket flour, silkworm pupae powder and black cricket powder.

Are deep eutectic solvents useful in chromatography? A short review

A literature update has been done concerning Deep Eutectic Solvents (DES) use in chromatography applications. The literature survey was based on the period from 2010 till 2020 and manuscripts reported in the data bases Web of Science and Scopus. The use of DES as mobile phase and mobile phase additives, stationary phases and solid phase modifiers and the use of DES as reaction solvents for chromatography use, were evaluated. Emphasis was placed on the differentiation of DES and Ionic Liquids (ILs) and the advanced green characteristics of the new solvents as compared with traditional organic solvents and ILs with a look into the drawbacks and future perspectives in the field of separation methods.

Natural Compounds for the Prevention and Treatment of Cardiovascular and Neurodegenerative Diseases

Secondary metabolites from plants and fungi are stimulating growing interest in consumers and, consequently, in the food and supplement industries. The beneficial effects of these natural compounds are being thoroughly studied and there are frequent updates about the biological activities of old and new molecules isolated from plants and fungi. In this article, we present a review of the most recent literature regarding the recent discovery of secondary metabolites through isolation and structural elucidation, as well as the in vitro and/or in vivo evaluation of their biological effects. In particular, the possibility of using these bioactive molecules in the prevention and/or treatment of widely spread pathologies such as cardiovascular and neurodegenerative diseases is discussed.

One-step deep eutectic solvent strategy for efficient analysis of aflatoxins in edible oils

BACKGROUND

Aflatoxins, a kind of carcinogen, have attracted increasing attention due to their toxicity and harmfulness to human health. Traditional methods for aflatoxins analysis usually involve tedious extraction steps with a subsequent derivatization process. Herein, a simple and efficient liquid-phase microextraction method based on deep eutectic solvents (DESs) for direct analysis of aflatoxins was developed.

RESULTS

Adopting DESs as the extractant, we surprisingly found out that DESs could either achieve good extraction performance or play a similar role to the derivatization agent, achieving an enhancement of fluorescence intensity for direct analysis of aflatoxins by high-performance liquid chromatography combined with fluorescent detection. Under optimal conditions obtained by response surface methodology, the method provided satisfactory linear ranges (0.01-0.75 μg kg^-1 for AFB1 and AFG1, 0.003-0.25 μg kg^-1 for AFB2 and AFG2) with good determination coefficients (R²  > 0.9988), a low detection limit (0.0005-0.003 μg kg^-1 ), and good recovery rates (72.05-113.54%).

CONCLUSION

These results highlighted superiorities of the one-step DES strategy for analysis of aflatoxins in edible oils, providing insights for future development of efficient methods in food analysis. © 2020 Society of Chemical Industry.

Deep Eutectic Solvents as Effective Reaction Media for the Synthesis of 2-Hydroxyphenylbenzimidazole-based Scaffolds en Route to Donepezil-Like Compounds

An unsubstituted 2-hydroxyphenylbenzimidazole has recently been included as a scaffold in a series of hybrids (including the hit compound PZ1) based on the framework of the acetylcholinesterase (AChE) inhibitor Donepezil, which is a new promising multi-target ligand in Alzheimer’s disease (AD) treatment. Building upon these findings, we have now designed and completed the whole synthesis of PZ1 in the so-called deep eutectic solvents (DESs), which have emerged as an unconventional class of bio-renewable reaction media in green synthesis. Under optimized reaction conditions, the preparation of a series of 2-hydroxyphenylbenzimidazole-based nuclei has also been perfected in DESs, and comparison with other routes which employ toxic and volatile organic solvents (VOCs) provided. The functionalization of the aromatic ring can have implications on some important biological properties of the described derivatives and will be the subject of future studies of structure-activity relationships (SARs).

Natural deep eutectic solvents and aqueous solutions as an alternative extraction media for propolis

Ethanolic extracts of propolis are consumed for their health benefits even though direct consumption of alcoholic extracts is not always ideal. Natural Deep Eutectic Solvents (NADES) can potentially extract similar compounds as alcoholic extracts while being better for direct consumption. Therefore, in this work alternative solvents for the extraction of green propolis including its biomarker artepillin C were examined. Sixteen NADES made from low toxicity chemicals, including the essential amino acid l-lysine, were explored along with twelve individual NADES components and honey, which showed similar physical-chemical properties to NADES. At 50 °C NADES made from choline chloride-propylene glycol or lactic acid proved to be equal or better than the benchmark EtOH:Water 7:3 (v/v). Alternatively, aqueous l-lysine appeared as a potential solvent for the preparation of aqueous propolis extracts. From these findings NADES, honey and aqueous l-lysine solutions all demonstrated the potential to replace ethanol or water for extracting green propolis.

Green pre-concentration techniques during pesticide analysis in food samples

The ever-increasing demand for determining pesticides at low concentration levels in different food matrices requires a preliminary step of pre-concentration which is considered a crucial stage. Recently, the parameter of "greenness" during sample pre-concentration of pesticides in food matrices is as important as selectivity in order to avoid using harmful organic solvents during sample preparation. Developing new green pre-concentration techniques is one of the key subjects. Thus, to reduce the impact on the environment during trace analysis of pesticides in food matrices, new developments in pre-concentration have gone in three separate directions: the search for more environmentally friendly solvents, miniaturization and development of solvent-free pre-concentration techniques. Eco-friendly solvents such as supercritical fluids, ionic liquids and natural deep eutectic solvents have been developed for use as extraction solvents during pre-concentration of pesticides in food matrices. Also, miniaturized pre-concentration techniques such as QuEChERS, dispersive liquid-liquid micro-extraction and hollow-fiber liquid-phase micro-extraction have been used during trace analysis of pesticides in food samples as well as solvent-free techniques such as solid-phase micro-extraction and stir bar sorptive extraction. All these developments which are aimed at ensuring that pesticide pre-concentration in different food matrices is green are critically reviewed in this paper.

The Future of Polar Organometallic Chemistry Written in Bio-Based Solvents and Water

There is a strong imperative to reduce the release of volatile organic compounds (VOCs) into the environment, and many efforts are currently being made to replace conventional hazardous VOCs in favour of safe, green and bio-renewable reaction media that are not based on crude petroleum. Recent ground-breaking studies from a few laboratories worldwide have shown that both Grignard and (functionalised) organolithium reagents, traditionally handled under strict exclusion of air and humidity and in anhydrous VOCs, can smoothly promote both nucleophilic additions to unsaturated substrates and nucleophilic substitutions in water and other bio-based solvents (glycerol, deep eutectic solvents), competitively with protonolysis, at room temperature and under air. The chemistry of polar organometallics in the above protic media is a complex phenomenon influenced by several factors, and understanding its foundational character is stimulating in the perspective of the development of a sustainable organometallic chemistry.

Biorenewable Deep Eutectic Solvent for Selective and Scalable Conversion of Furfural into Cyclopentenone Derivatives

The development of novel synthetic routes to produce bioactive compounds starting from renewable sources has become an important research area in organic and medicinal chemistry. Here, we present a low-cost procedure for the tunable and selective conversion of biomass-produced furfural to cyclopentenone derivatives using a mixture of choline chloride and urea as a biorenewable deep eutectic solvent (DES). The proposed medium is a nontoxic, biodegradable, and could be reused up to four times without any unfavorable effect on the reaction yield. The process is tunable, clean, cheap, simple and scalable and meets most of the criteria; therefore, it can be considered as an environmental sustainable process in a natural reaction medium.

Broad range chemical profiling of natural deep eutectic solvent extracts using a high performance thin layer chromatography-based method

Natural deep eutectic solvents (NADES) made mainly with abundant primary metabolites are being increasingly applied in green chemistry. The advantages of NADES as green solvents have led to their use in novel green products for the food, cosmetics and pharma markets. However, one of the main difficulties encountered in the development of novel products and their quality control arises from their low vapour pressure and high viscosity. These features create the need for the development of new analytical methods suited to this type of sample. In this study, such a method was developed and applied to analyse the efficiency of a diverse set of NADES for the extraction of compounds of interest from two model plants, Ginkgo biloba and Panax ginseng. The method uses high-performance thin-layer chromatography (HPTLC) coupled with multivariate data analysis (MVDA). It was successfully applied to the comparative quali- and quantitative analysis of very chemically diverse metabolites (e.g., phenolics, terpenoids, phenolic acids and saponins) that are present in the extracts obtained from the plants using six different NADES. The composition of each NADES was a combination of two or three compounds mixed in defined molar ratios; malic acid-choline chloride (1:1), malic acid-glucose (1:1), choline chloride-glucose (5:2), malic acid-proline (1:1), glucose-fructose-sucrose (1:1:1) and glycerol-proline-sucrose (9:4:1). Of these mixtures, malic acid-choline chloride (1:1) and glycerol-proline-sucrose (1:1:1) for G. biloba leaves, and malic acid-choline chloride (1:1) and malic acid-glucose (1:1) for P. ginseng leaves and stems showed the highest yields of the target compounds. Interestingly, none of the NADES extracted ginkgolic acids as much as the conventional organic solvents. As these compounds are considered to be toxic, the fact that these NADES produce virtually ginkgolic acid-free extracts is extremely useful. The effect of adding different volumes of water to the most efficient NADES was also evaluated and the results revealed that there is a great influence exerted by the water content, with maximum yields of ginkgolides, phenolics and ginsenosides being obtained with approximately 20% water (w/w).

Deep eutectic liquid organic salt as a new solvent for carrier-mediated hollow fiber liquid phase microextraction of lead from whole blood followed by electrothermal atomic absorption spectrometry

In the present work, for the first time, a new carrier-mediated hollow fiber liquid phase microextraction (CM-HFLPME) technique was applied for the determination of lead in whole blood samples by means of ETAAS.