Interactions of natural deep eutectic solvents (NADES) with artificial and natural membranes

Structural characterization and physicochemical properties of different hydrophilic natural deep eutectic solvents

To overcome the toxic nature of organic solvents, scientific interest in the use of green solvents, particularly natural deep eutectic solvents (NADES), has increased over the past decade, leading to new applications in the food, nutraceutical, pharmaceutical, and cosmetic industries. Understanding the physicochemical properties and molecular interactions of NADES is essential for uncovering new potential applications in these fields. In this study, several lactic and citric acid-based NADES, as well as chloride choline- and urea-based NADES, were evaluated for their physicochemical properties, including density, pH, viscosity, conductivity, and refractive index. Additionally, nuclear magnetic resonance (NMR), and in particular nuclear Overhauser enhancement spectroscopy (NOESY), was employed to investigate the intermolecular interactions between the NADES components to confirm the formation of the eutectic mixture. The extraction efficiency of the confirmed NADES was tested for extracting polyphenols as a proof of concept to highlight their relationship with the measured properties. Lactic and choline chloride-based NADES provided the highest extraction yields. These results were also compared with the predicted extraction capabilities of each NADES provided by the COSMO-RS software.

Reshaping Capillary Electrophoresis With State-of-the-Art Sample Preparation Materials: Exploring New Horizons

Capillary electrophoresis (CE) is a powerful analysis technique with advantages such as high separation efficiency with resolution factors above 1.5, low sample consumption of less than 10 µL, cost-effectiveness, and eco-friendliness such as reduced solvent use and lower operational costs. However, CE also faces limitations, including limited detection sensitivity for low-concentration samples and interference from complex biological matrices. Prior to performing CE, it is common to utilize sample preparation procedures such as solid-phase microextraction (SPME) and liquid-phase microextraction (LPME) in order to improve the sensitivity and selectivity of the analysis. Recently, there have been advancements in the development of novel materials that have the potential to greatly enhance the performance of SPME and LPME. This review examines various materials and their uses in microextraction when combined with CE. These materials include carbon nanotubes, covalent organic frameworks, metal-organic frameworks, graphene and its derivatives, molecularly imprinted polymers, layered double hydroxides, ionic liquids, and deep eutectic solvents. The utilization of these innovative materials in extraction methods is being examined. Analyte recoveries and detection limits attained for a range of sample matrices are used to assess their effects on extraction selectivity, sensitivity, and efficiency. Exploring new materials for use in sample preparation techniques is important as it enables researchers to address current limitations of CE. The development of novel materials has the potential to greatly enhance extraction selectivity, sensitivity, and efficiency, thereby improving CE performance for complex biological analysis.

Integrating Natural Deep Eutectic Solvents into Nanostructured Lipid Carriers: An Industrial Look

The industries are searching for greener alternatives for their productions due to the rising concern about the environment and creation of waste and by-products without industrial utility for that specific line of products. This investigation describes the development of two stable nanostructured lipid carriers (NLCs): one is the formulation of a standard NLC, and the other one is the same NLC formulation associated with a natural deep eutectic solvent (NaDES). The research presents the formulation paths of the NLCs through completeness, which encompass dynamic light scattering (DLS), zeta potential tests, and pH. Transmission electron microscopy (TEM) and confocal microscopy were performed to clarify the morphology. Cytotoxicity tests with zebrafish were realized, and the results are complementary to the in vitro outcomes reached with fibroblast L132 tests by the MTT technique and the zymography test. Infrared spectroscopy and X-ray diffractometry tests elucidated the link between the physicochemical characteristics of the formulation and its behavior and properties. Different cooling techniques were explored to prove the tailorable properties of the NLCs for any industrial applications. In conclusion, the compiled results show the successful formulation of new nanocarriers based on a sustainable, eco-friendly, and highly tailorable technology, which presents low cytotoxic potential.

Valorization of artichoke outer petals by using ultrasound-assisted extraction and natural deep eutectic solvents (NADES) for the recovery of phenolic compounds

BACKGROUND

In the present study, natural deep eutectic solvents (NADES) as a novel green tool were used for the recovery of bioactive compounds with respect to the valorization of artichoke outer petals. NADES coupled with ultrasound-assisted extraction was applied by varying the type of hydrogen bond acceptors (choline chloride or betain) and hydrogen bond donors (sucrose, lactic acid, citric acid, oxalic acid and glycerol) in the NADES mixtures. Thereafter, extraction efficacy was assessed in terms of total phenolic content, antioxidant capacity and individual phenolic composition and their levels by comparing the results obtained by NADES with those for a reference methanolic extract.

RESULTS

Based on the results of the present study, the use of choline chloride and lactic acid mixtures was superior for obtaining extracts with high levels of phenolic compounds (12.96 g GAE kg-1 DW) and high antioxidant potential (60.68 g TE kg-1 DW). In addition, gallic acid, syringic acid, chlorogenic acid, ferulic acid, sinapic acid, luteolin, apigenin, rutin and quercetin were detected in all extracts by chromatographic evaluation. As major phenolic compounds, chlorogenic acid and ferulic acid were found to be maximum in lactic acid-based NADES mixtures.

CONCLUSION

The present study reveals the potential treatment of various plants, wastes or by-products with NADES combined with an ultrasonication method for the extraction of bioactive compounds with enhanced recovery and selectivity, with the aim of incorporating them into various food and pharmaceutical formulations. © 2023 The Authors. Journal of The Science of Food and Agriculture published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry.

Neutral natural deep eutectic solvents as anti-biofilm agents

Natural deep eutectic solvents (NADES) are a class of liquids with promising properties as components in pharmaceutical formulations, such as a low toxicity profile, biodegradability and versatility. Recently, their potential use as anti-biofilm agents has been proposed, due to their ability to solubilize and stabilize biological macromolecules. In the current work, the ability to break down biofilm matrix and the biofilm killing activity of three NADES of neutral pH were investigated against Staphylococcus aureus ATCC 6538 and Pseudomonas aeruginosa ATCC 9027 biofilms. The tested NADES were choline chloride:xylitol (ChX), choline chloride:glycerol (ChG) and betaine:sucrose (BS). Two of the NADES (ChX and ChG) significantly reduced the number of remaining viable cells of both bacterial species in pre-formed biofilm by 4-6 orders of magnitude, while the average biofilm biomass removal for all NADES was 27-67% (S. aureus) and 34-49% (P. aeruginosa). The tested NADES also inhibited biofilm formation of both bacterial species at concentrations at or below 0.5 x the minimal inhibitory concentration (MIC), possibly in part due to observed restrictions imposed by NADES on planktonic growth. These results demonstrate the potential value of neutral NADES as anti-biofilm agents in future antimicrobial preparations.

From Nature to Innovation: The Uncharted Potential of Natural Deep Eutectic Solvents

This review discusses the significance of natural deep eutectic solvents (NaDESs) as a promising green extraction technology. It employs the consolidated meta-analytic approach theory methodology, using the Web of Science and Scopus databases to analyze 2091 articles as the basis of the review. This review explores NaDESs by examining their properties, challenges, and limitations. It underscores the broad applications of NaDESs, some of which remain unexplored, with a focus on their roles as solvents and preservatives. NaDESs' connections with nanocarriers and their use in the food, cosmetics, and pharmaceutical sectors are highlighted. This article suggests that biomimicry could inspire researchers to develop technologies that are less harmful to the human body by emulating natural processes. This approach challenges the notion that green science is inferior. This review presents numerous successful studies and applications of NaDESs, concluding that they represent a viable and promising avenue for research in the field of green chemistry.

Ecotoxicological study of glucose:choline chloride and sorbitol:choline chloride at different contents of water

The search of new solvents is currently focused on deep eutectic solvents (DES). However, there are not many ecotoxicological studies in different biomodels of DES that allow knowing how these chemicals affect to the environment along the trophic chain. In this manuscript, two DES at different proportion of water have been prepared and characterized from the ecotoxicological point of view. These solvents are glucose:choline chloride (2:5) and sorbitol:choline chloride (3:2) at different contents of water. To carry out the ecotoxicological study, three biomodels have been used: bacteria Aliivibrio fisheri (A. fisheri), crustacean Daphnia magna (D. magna) and algae Raphidocelis subcapitata (R. subcapitata). The obtained results show that the ecotoxicity of these chemicals depends on the biomodel used and the amount of water, being toxicity values lower for chemicals with higher water content. However, it is important to highlight that the ecotoxicity for all chemicals is quite low with effective concentrations, EC₅₀ values above 1000 mg/L in all the studied cases.

Phenolic compounds extraction by assistive technologies and natural deep eutectic solvents

Phenolic compounds are known to have a significant effect on human defense system due to their anti-inflammatory efficacy. This can slow down the aging process and strengthen the human immune system. With the growing interest in green chemistry concept, extraction of phenolic compounds from plants has been geared towards a sustainable path with the use of green and environmentally friendly solvents such as natural deep eutectic solvents (NADES). This review discusses both the conventional extraction and the advanced extraction methods of phenolic compounds using NADES with focus on microwave-assisted extraction (MAE) and ultrasound-assisted extraction (UAE) techniques ensued by a rationale comparison between them. Employing choline chloride-based natural deep eutectic solvents (NADES) is highlighted as one of the promising strategies in green solvent extraction of phenolic compounds in terms of their biodegradability and extraction mechanism. The review also discusses assistive extraction technologies using NADES for a better understanding of their relationship with extraction efficiency. In addition, the review includes an overview of the challenges of recovering phenolic compounds from NADES after extraction, the potential harmful effects of NADES as well as their future perspective.

Applications of New Generation Solvents for Extraction of Herbal Products Prior to Atomic and Molecular Analysis

In this review, an up to date and current knowledge of some of the green solvents, which includes supercritical fluids extraction (SFE), switchable polarity solvents (SPS), and natural deep eutectic solvents (NADES) are discussed with more emphasis on the extraction of active components of herbal products. Different scientific articles and books have been researched and reviewed to explain the applications of new generation solvents for extraction of herbal products prior to atomic and molecular analysis from the past until now. Currently, the most of techniques used in processing herbal products involve the use of extraction methods. Therefore, trends in extraction methods focuses mainly on finding reasonable solutions that minimizes the use of toxic solvents and allows the usage of renewable and green solvents from natural products, which ensure high quality and safe extracts. In future, SFE is definitely going to be on the industrial scale due to its numerous applications in the large scale especially for herbal, food, cosmetics and pharmaceutical products etc.

Determination of quinolone antibiotics in honey by pH-induced natural deep eutectic solvent combined with vortex-assisted dispersive liquid-liquid microextraction

A green, fast, and efficient pH-induced natural deep eutectic solvent combined with vortex-assisted dispersive liquid-liquid microextraction method (pH-NADES-VA-DLLME) followed by HPLC was established for determination of ofloxacin (OFL), ciprofloxacin (CIP) and enrofloxacin (ENR) in honey. In this method, NaOH, as an emulsifier, can increase the contact area between the NADES and the sample solution, which can efficiently improve the extraction efficiency of the analytes. Moreover, HCl acts as the phase separation agent without centrifugation in the process, which can greatly enhance the efficiency of the sample analysis process. In addition, the main factors affecting the extraction effect were optimized by single factor experiments. Under the optimal conditions, the limits of detection (LODs), the limits of quantification (LOQs) and recoveries were in the range of 0.004-0.015 μg mL^-1, 0.012-0.050 μg mL^-1, and 98.0-112.5%, respectively. The RSD values of intra-day and inter-day precisions were no more than 5.5% and 6.0%, respectively. The developed method was successfully applied to determine the three quinolone antibiotics in honey.

Interaction mechanism of three egg protein derived ACE inhibitory tri-peptides and DPPC membrane using FS, FTIR, and DSC studies

Understanding the interaction of food derived angiotensin converting enzyme (ACE) inhibitory peptides and intestinal epithelial cell membrane may help to improve their absorption. This research aimed to study the molecular interaction of ACE inhibitory tri-peptides ADF, FGR, and MIR with DPPC membrane during absorption process. The DPPC liposome was prepared and characterized, then used as a model membrane. The permeability of tri-peptides across the membrane was investigated using Fluorescence spectroscopy. The effect of tri-peptides on the structure and dynamics of DPPC bilayers was determined using Fourier transform infrared spectroscopy. The effect of tri-peptides on the phase transition temperature in the DPPC membrane was also analyzed using Differential scanning calorimetry. The results showed that ACE inhibitory tri-peptides ADF, FGR, and MIR can penetrate into both the membrane-water interface and hydrophobic region of DPPC bilayer, and the tri-peptide FGR have higher permeability across the membrane.

Monitoring the water content in NADES extracts from spirulina biomass by means of ATR-IR spectroscopy

Attenuated total reflectance-infrared spectroscopy (ATR-IR) coupled with partial least squares regression (PLSR) was evaluated as a rapid, label free and cost-effective tool to quantify water content in extracts obtained from spirulina wet biomass using a glucose glycerol natural deep eutectic solvent (NADES). NADESs are green, renewable and biodegradable solvents with unique properties outcompeting existing organic solvents, for instance, for plant or biomass extraction. The properties of NADESs depend critically on their water concentration, and therefore, it is essential to develop methods to monitor it, to ensure optimal extraction efficiency and experimental repeatability to achieve a better standardization of extraction protocols. First, Karl Fischer titration was performed on a set of 20 NADES extracts in order to obtain reference water concentrations. Secondly, ATR-IR spectra were collected and subjected to datamining to construct PLSR predictive models. An R² value of 0.9996, a mean root mean square error of cross validation of 0.136% w/w and a root mean square error of prediction of 0.130% w/w highlight the feasibility and reliability to perform quantitative analysis using ATR-IR. Moreover, the mean relative error percentage achieved, ∼0.5%, confirms the high accuracy of water concentration determination in NADES extracts. This work demonstrates that powerful alternatives are available to provide more environmentally responsible analytical protocols. ATR-IR spectroscopy applied to NADES extracts does not require any sample preparation, reagents or solvents and has minimal requirements for single use consumables. The technique is consistent with current concerns to develop greener chemistry, especially in the field of extraction of natural compounds from plants which currently represents a major focus of interest in both research and industry.

Grape Pomace for Topical Application: Green NaDES Sustainable Extraction, Skin Permeation Studies, Antioxidant and Anti-Inflammatory Activities Characterization in 3D Human Keratinocytes

Food waste is a global problem due to its environmental and economic impact, so there is great demand for the exploitation of new functional applications. The winemaking process leads to an incomplete extraction of high-value compounds, leaving the pomace still rich in polyphenols. This study was aimed at optimising and validating sustainable routes toward the extraction and further valorisation of these polyphenols, particularly for cosmeceutical applications. New formulations based on red grape pomace polyphenols and natural deep eutectic solvents (NaDESs) were here investigated, namely betaine combined with citric acid (BET-CA), urea (BET-U) and ethylene glycol (BET-EG), in which DESs were used both as extracting and carrying agents for polyphenols. The flavonoid profile determined by HPLC-MS/MS analysis showed similar malvidin content (51-56 μg mL^-1) in the DES combinations, while BET-CA gave the best permeation performance in Franz cells, so it was further investigated in 3D human keratinocytes (HaCat spheroids) injured with the pro-oxidant agent menadione. BET-CA treatment showed good intracellular antioxidant activity (IC50 0.15 ± 0.02 μg mL^-1 in malvidin content) and significantly decreased (p < 0.001) the release of the pro-inflammatory cytokine IL-8, improving cell viability. Thus, BET-CA formulation is worthy of investigation for potential use as a cosmetic ingredient to reduce oxidative stress and inflammation, which are causes of skin aging.

Promising Technological and Industrial Applications of Deep Eutectic Systems

Deep Eutectic Systems (DESs) are obtained by combining Hydrogen Bond Acceptors (HBAs) and Hydrogen Bond Donors (HBDs) in specific molar ratios. Since their first appearance in the literature in 2003, they have shown a wide range of applications, ranging from the selective extraction of biomass or metals to medicine, as well as from pollution control systems to catalytic active solvents and co-solvents. The very peculiar physical properties of DESs, such as the elevated density and viscosity, reduced conductivity, improved solvent ability and a peculiar optical behavior, can be exploited for engineering modular systems which cannot be obtained with other non-eutectic mixtures. In the present review, selected DESs research fields, as their use in materials synthesis, as solvents for volatile organic compounds, as ingredients in pharmaceutical formulations and as active solvents and cosolvents in organic synthesis, are reported and discussed in terms of application and future perspectives.