Natural Deep Eutectic Solvents for the Extraction of Bioactive Steroidal Saponins from Dioscoreae Nipponicae Rhizoma

A high-permeability method for extracting purple yam saponins based on ultrasonic-assisted natural deep eutectic solvent

The extraction of active ingredients from traditional Chinese medicine has received considerable attentions. In this study, 16 kinds of natural deep eutectic solvent (NADES) with ultrasonic were selected to extract saponins from purple yam root and the extraction mechanism was investigated. The results showed that chloride/acrylic acid (1:2; n/n) had the highest extraction yield for saponins. The optimal extraction process parameters were 24% water content, 20 mL/g liquid-solid ratio, and ultrasonic extraction for 85 min (81 °C, 600 W). The extraction rate (ER) of purple yam saponins was 0.935%, close to the fitted result of 96.5 mg/g. Molecular dynamics simulations and FT-IR results showed that the NADES may extract the saponin constituents from purple yam through hydrogen bonding. Compared with traditional extraction methods and molecularly imprinted polymer methods, NADES has a higher ER and lower cost (1.53 $/g), which provides a reference for subsequent industrial quantitative production.

Widely targeted metabolomic and KEGG analyses of natural deep eutectic solvent-based saponins extraction from Camellia oleifera Abel.: Effects on composition

Camellia saponins are important by-products of Camellia Oleifer Abel. processing. In this study, an eco-friendly method based on natural deep eutectic solvents (NaDESs, proline and glycerol at a molar ratio of 2:5) was established to extract saponins from C.oleifera cakes. The content of saponin (702.22 ± 1.28 mg/g) obtained using NaDES was higher than those extracted using water or methanol. UPLC-Q-TOF MS analysis of chemical structure showed that the difference in the extraction technique alter individual saponins. A widely targeted metabolomic approach and KEGG metabolic pathway analysis showed that the upregulated metabolites in the NaDES-based extract mainly included flavonoids, alkaloids, and phenolic acids; and they were involved in arginine and proline metabolism, metabolic pathways, phenylpropanoid biosynthesis, biosynthesis of secondary metabolites, and flavonoid biosynthesis. The present study proposes a selective substitute for use in the extraction of camellia saponins with composition analysis.

NADES extraction, UHPLC-ELSD-based quantification, and network pharmacology-guided target identification of fourteen specialised metabolites from Trillium govanianum Wall. ex D.Don

INTRODUCTION

Trillium govanianum Wall. ex D.Don is a folk medicinal herb rich in structurally diverse steroidal saponins. The annual demand for this herb in India is about 200-500 metric tons, highlighting the need for a thorough quality assessment.

OBJECTIVE

The objective of this study is to develop an easy and reliable ultrahigh-performance liquid chromatography-evaporative light scattering detector (UHPLC-ELSD)-based quality assessment method with 14 specialised metabolites of T. govanianum and identify the potential targets of this herb using network pharmacology.

MATERIAL AND METHODS

A UHPLC-ELSD method was developed and validated with 14 markers of T. govanianum. The developed method and natural deep eutectic solvent (NADES)-assisted extraction were utilised for the recovery enhancement study of targeted specialised metabolites from rhizome samples (collected from five geographically distinct areas). In addition, the network pharmacology approach was performed for these 14 markers to predict the plausible biological targets of T. govanianum.

RESULT

The developed method showed good linearity (r2: 0.940-0.998), limit of detection (LOD) (2.4-9.0 μg), limit of quantification (LOQ) (7.92-29.7 μg), precision (intra-day relative standard deviations [RSDs] 0.77%-1.96% and inter-day RSDs 2.19-4.97%), and accuracy (83.24%-118.90%). NADES sample TG-1* showed the highest recovery (yield: 167.66 ± 4.39 mg/g of dry weight) of total saponin content (TSC) as compared to its hydroethanolic extract (yield: 103.95 ± 5.36 mg/g of dry weight). Sample TG-1* was the most favourable (yield: 167.66 ± 4.39 mg/g) in terms of TSC as compared to other analysed samples (32.68 ± 1.04-88.22 ± 6.79 mg/g). Govanoside D (yield: 3.43-28.06 mg/g), 22β-hydroxyprotodioscin (yield: 3.22-114.79 mg/g), and dioscin (yield: 1.07-20.82 mg/g) were quantified as the major metabolites. Furthermore, network pharmacology analysis of targeted 14 markers indicated that these molecules could be possible therapeutic agents for managing neuralgia, diabetes mellitus, and hyperalgesia.

CONCLUSION

The current study represents the first report for the simultaneous quantification and a network pharmacology-based analysis of 14 chemical marker compounds isolated from T. govanianum.

Towards green extraction of bioactive natural compounds

The increasing interest in natural bioactive compounds is pushing the development of new extraction processes that may allow their recovery from a variety of different natural matrices and biomasses. These processes are clearly sought to be more environmentally friendly than the conventional alternatives that have traditionally been used and are closely related to the 6 principles of green extraction of natural products. In this trend article, the most critical aspects regarding the current state of this topic are described, showing the different lines followed to make extraction processes greener, illustrated by relevant examples. These include the implementation of new extraction technologies, the research on new bio-based solvents, and the development of new sequential process and biorefinery approaches to produce a full valorization of the natural sources. Moreover, the future outlook in the field is presented, in which the main areas of evolution are identified and discussed.

Natural Deep Eutectic Solvents for the Extraction of Spilanthol from Acmella oleracea (L.) R.K.Jansen

With a growing focus on green chemistry, the extraction of natural products with natural deep eutectic solvents (NADES), which are eutectic mixtures of hydrogen bond donors and acceptors, has become an ever-expanding field of research. However, the use of NADES for the extraction of spilanthol from Acmella oleracea (L.) R.K.Jansen has not yet been investigated. Therefore, in this study, 20 choline chloride-based NADES, and for comparison, ethanol, were used as green extraction agents for spilanthol from Acmella oleracea flower heads. The effects of time, water addition, and temperature on NADES extractions were investigated and analysed by HPLC-DAD quantification. Additionally, UHPLC-DAD-ESI-MSn results for dichloromethane extracts, as well as the isolation of spilanthol and other main constituents as reference compounds, are reported. The best green extraction results were achieved by choline chloride (ChCl) with 1,2-propanediol (P, 1:2 molar ratio, +20% water) at 244.58 µg/mL, comparable to yields with ethanol (245.93 µg/mL). Methylurea (MeU, 1:2, +20% water) also showed promising results as a hydrogen bond donor in combination with choline chloride (208.12 µg/mL). In further experiments with NADES ChCl/P (1:2) and ChCl/MeU (1:2), extraction time had the least effect on spilanthol extraction with NADES, while yield decreased with water addition over 20% and increased with extraction temperature up to 80 °C. NADES are promising extraction agents for the extraction of spilanthol, and these findings could lead to applicable extracts for medicinal purposes, due to their non-toxic constituents.

Recovery and separation of glycyrrhizic acid from Natural Deep Eutectic Solvent (NADES) extract by macroporous resin: adsorption kinetics and isotherm studies

Natural Deep Eutectic Solvents (NADESs) have emerged as a green and sustainable alternative to conventional organic solvents to extract bioactive compounds. However, the recovery of bioactive compounds from the NADES extracts is challenging, restricting their large-scale applications. The present work investigated the recovery of glycyrrhizic acid (GA) from choline-chloride/lactic acid NADES extract using macroporous resins. GA possesses a wide spectrum of biological activities, and it is extracted from the well-known herb Glycyrrhiza glabra. During resin screening, DIAIONTM SP700 showed high adsorption and desorption capacities. The adsorption kinetics study demonstrated that the adsorption of GA on SP700 followed Pseudo First-order kinetic model. Moreover, the adsorption behaviors were elucidated by the Freundlich isotherm using a correlation coefficient based on a static adsorption study at different temperatures and pH. Furthermore, the thermodynamic parameters, for instance, the change of Gibbs free energy (ΔG*), entropy (ΔS*), and enthalpy (ΔH*), showed that the adsorption process was spontaneous, favorable and exothermic. In addition, the sample after macroporous resin treatment, which is enriched with GA exhibited good anticancer potential analyzed by SRB assay. The regenerated NADES solvent was recycled twice, keeping more than 90% extraction efficiency, indicating good reusability of NADES in the GA extraction process by using macroporous resin.

Natural Deep Eutectic Solvent based Ultrasound-assisted extraction: A green approach for extraction of sulfhydryl and mimosine from Leucaena leucocephala (Lam) de Wit seeds

Leucaena leucocephala (Lam.) de Wit seeds, also known as river tamarind, contain sulfhydryl compounds that exhibit antioxidant effects. However, these seeds also possess a toxic effect from mimosine. In this study, the river tamarind seeds were extracted using a natural deep eutectic solvent (NADES) based UAE. Among six NADES compositions screened, choline chloride-glycerol (ChCl-Gly) and choline chloride-sucrose (ChCl-Suc) were selected to be further optimized using a Box-Behnken Design in the RSM. The optimization of total sulfhydryl content was performed in 17 runs using three variables, namely water content in NADES (39%, 41%, and 43%), extraction time (5, 10, and 15 min), and the liquid-solid ratio (3, 5, and 7 mL/g). The highest concentration of sulfhydryls was obtained from ChCl-Gly-UAE (0.89 mg/g sample) under the conditions of a water content in NADES of 41% (v/v) and a liquid-solid ratio of 3 mL/g for 15 min, followed by that of from ChCl-Suc-UAE extract under the conditions of water content in NADES of 43% (v/v) and the liquid-solid ratio of 3 mL/g for 10 min with total sulfhydryl level was 0.67 mg/g sample. The maceration method using 30% ethanol resulted in the lowest level of sulfhydryls with a value of 0.52 mg/g. The mimosine compounds obtained in the NADES-based UAE (ChCl-Suc and ChCl-Gly) extracts were 4.95 and 7.67 mg/g, respectively, while 12.56 mg/g in the 30% ethanol-maceration extract. The surface morphology of L. leucocephala seed before and after extraction was analyzed using scanning electron microscopy. Therefore, it can be concluded that the use of ChCl-Suc and ChCl-Gly in NADES-based UAE is more selective in attracting sulfhydryl compounds than that of 30% ethanol-maceration extraction.

The Most Potent Natural Pharmaceuticals, Cosmetics, and Food Ingredients Isolated from Plants with Deep Eutectic Solvents

There is growing interest in reducing the number of synthetic products or additives and replacing them with natural ones. The pharmaceutical, cosmetic, and food industries are especially focused on natural and bioactive chemicals isolated from plants or microorganisms. The main challenge here is to develop efficient and ecological methods for their isolation. According to the strategies and rules of sustainable development and green chemistry, green solvents and environmentally friendly technologies must be used. The application of deep eutectic solvents as efficient and biodegradable solvents seems to be a promising alternative to traditional methods. They are classified as being green and ecological but, most importantly, very efficient extraction media compared to organic solvents. The aim of this review is to present the recent findings on green extraction, as well as the biological activities and the possible applications of natural plant ingredients, namely, phenolics, flavonoids, terpenes, saponins, and some others. This paper thoroughly reviews modern, ecological, and efficient extraction methods with the use of deep eutectic solvents (DESs). The newest findings, as well as the factors influencing the efficiency of extraction, such as water content, and hydrogen bond donor and acceptor types, as well as the extraction systems, are also discussed. New solutions to the major problem of separating DESs from the extract and for solvent recycling are also presented.

Dietary Fiber from Navel Orange Peel Prepared by Enzymatic and Ultrasound-Assisted Deep Eutectic Solvents: Physicochemical and Prebiotic Properties

Dietary fiber (DF) was extracted from navel orange peel residue by enzyme (E-DF) and ultrasound-assisted deep eutectic solvent (US-DES-DF), and its physicochemical and prebiotic properties were characterized. Based on Fourier-transform infrared spectroscopy, all DF samples exhibited typical polysaccharide absorption spectra, indicating that DES could separate lignin while leaving the chemical structure of DF unchanged, yielding significantly higher extraction yields (76.69 ± 1.68%) compared to enzymatic methods (67.27 ± 0.13%). Moreover, ultrasound-assisted DES extraction improved the properties of navel orange DFs by significantly increasing the contents of soluble dietary fiber and total dietary fiber (3.29 ± 1.33% and 10.13 ± 0.78%, respectively), as well as a notable improvement in the values of water-holding capacity, oil-holding capacity, and water swelling capacity. US-DES-DF outperformed commercial citrus fiber in stimulating the proliferation of probiotic Bifidobacteria strains in vitro. Overall, ultrasound-assisted DES extraction exhibited potential as an industrial extraction method, and US-DES-DF could serve as a valuable functional food ingredient. These results provide a new perspective on the prebiotic properties of dietary fibers and the preparation process of prebiotics.

Natural Deep Eutectic Solvents for the Extraction of Triterpene Saponins from Aralia elata var. mandshurica (Rupr. & Maxim.) J. Wen

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.

Major Phytochemicals: Recent Advances in Health Benefits and Extraction Method

Recent scientific studies have established a relationship between the consumption of phytochemicals such as carotenoids, polyphenols, isoprenoids, phytosterols, saponins, dietary fibers, polysaccharides, etc., with health benefits such as prevention of diabetes, obesity, cancer, cardiovascular diseases, etc. This has led to the popularization of phytochemicals. Nowadays, foods containing phytochemicals as a constituent (functional foods) and the concentrated form of phytochemicals (nutraceuticals) are used as a preventive measure or cure for many diseases. The health benefits of these phytochemicals depend on their purity and structural stability. The yield, purity, and structural stability of extracted phytochemicals depend on the matrix in which the phytochemical is present, the method of extraction, the solvent used, the temperature, and the time of extraction.

Applications for natural deep eutectic solvents in Chinese herbal medicines

Chinese herbal medicines (CHMs), with a wide range of bioactive components, are considered to be an important source for new drug discovery. However, the process to isolate and obtain those bioactive components to develop new drugs always consumes a large amount of organic solvents with high toxicity and non-biodegradability. Natural deep eutectic solvents (NADES), a new type of green and designable solvents composed of primary plant-based metabolites, have been used as eco-friendly substitutes for traditional organic solvents in various fields. Due to the advantages of easy preparation, low production cost, low toxicity, and eco-friendliness, NADES have been also applied as extraction solvents, media, and drug delivery agents in CHMs in recent years. Besides, the special properties of NADES have been contributed to elucidating the traditional processing (also named Paozhi in Chinese) theory of CHMs, especially processing with honey. In this paper, the development process, preparation, classification, and applications for NADES in CHMs have been reviewed. Prospects in the future applications and challenges have been discussed to better understand the possibilities of the new solvents in the drug development and other uses of CHMs.

Deep Eutectic Solvents as a Green Tool for the Extraction of Bioactive Phenolic Compounds from Avocado Peels

Avocado peels are the main agro-industrial residue generated during the avocado processing, being a rich source of bioactive compounds like phenolic compounds. The growing demand for more sustainable processes requires the development of new and effective methods for extracting bioactive compounds from industrial waste. Deep eutectic solvents (DESs) are a new sustainable alternative to toxic organic solvents due to their non-toxicity and biocompatibility. In this study, five selected DESs were applied for the extraction of bioactive phenolic compounds from avocado peels. The extraction efficiency was evaluated by measuring the total phenolics and flavonoids content. The best extraction results were obtained with choline chloride-acetic acid and -lactic acid (92.03 ± 2.11 mg GAE/g DAP in TPC and 186.01 ± 3.27 mg RE/g DAP); however, all tested DESs show better extraction efficiency than ethanol. All the obtained NADES extracts have high antioxidant activity (FRAP: 72.5-121.1 mg TE/g; TAC: 90.0-126.1 mg AAE/g). The synthesized DESs and avocado peels DES extracts had activity against all tested bacteria (Staphylococcus aureus, Streptococcus dysgalactiae, Escherichia coli and Pseudomonas putida), and the extracts prepared with choline chloride-acetic acid and -lactic acid have the highest antibacterial activity against all microorganisms. These results, coupled with the non-toxic, biodegradable, low-cost, and environmentally friendly characteristics of DESs, provide strong evidence that DESs represent an effective alternative to organic solvents for the recovery of phenolic bioactive compounds from agro-industrial wastes.

The Impact of Natural Deep Eutectic Solvents and Extraction Method on the Co-Extraction of Trace Metals from Fucus vesiculosus

In recent years, natural deep eutectic solvents (NADES) have been widely investigated for the extraction of food and medicinal plants as well as seaweeds. However, the ability of NADES for trace elements co-extraction from natural sources is not well investigated. The aim of this study was to investigate the ability of common NADES for trace elements co-extraction from Fucus vesiculosus. All of the tested NADES did not recover As and Co (concentration Collapse

Key Words

• Fucus vesiculosus
• NADES
• extraction
• hazard quotient
• health risk
• natural deep eutectic solvents
• trace elements
• trace metals

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MESH Headings

• Deep Eutectic Solvents
• Fucus
• Plant Extracts
• Solvents
• Water

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Grants

• 121091600104-7 Ministry of Science and Higher Education of the Russian Federation within the framework of the Government Assignment to the Murmansk Marine Biological Institute Russian Academy of Sciences
• 075-15-2021-685; dated 26 July 2021 on the provision of the federal budget grants Ministry of Science and Higher Education of the Russian Federation

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Affiliation(s)

Alexander N. Shikov Murmansk Marine Biological Institute of the Russian Academy of Sciences (MMBI RAS), Vladimirskaya, 17, 183010 Murmansk, Russia; (E.D.O.); (O.N.P.) Department of Pharmaceutical Formulations, St. Petersburg State Chemical Pharmaceutical University, Prof. Popov, 14, 197376 Saint-Petersburg, Russia;
Ekaterina D. Obluchinskaya Murmansk Marine Biological Institute of the Russian Academy of Sciences (MMBI RAS), Vladimirskaya, 17, 183010 Murmansk, Russia; (E.D.O.); (O.N.P.)
Elena V. Flisyuk Department of Pharmaceutical Formulations, St. Petersburg State Chemical Pharmaceutical University, Prof. Popov, 14, 197376 Saint-Petersburg, Russia;
Inna I. Terninko Core Shared Research Facilities “Analytical Center”, St. Petersburg State Chemical Pharmaceutical University, Prof. Popov, 14, 197376 Saint-Petersburg, Russia; (I.I.T.); (Y.E.G.)
Yulia E. Generalova Core Shared Research Facilities “Analytical Center”, St. Petersburg State Chemical Pharmaceutical University, Prof. Popov, 14, 197376 Saint-Petersburg, Russia; (I.I.T.); (Y.E.G.)
Olga N. Pozharitskaya Murmansk Marine Biological Institute of the Russian Academy of Sciences (MMBI RAS), Vladimirskaya, 17, 183010 Murmansk, Russia; (E.D.O.); (O.N.P.)

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Extraction of Bioactive Compounds From Cannabis sativa L. Flowers and/or Leaves Using Deep Eutectic Solvents

The increasing demand for medical cannabis urges the development of new and effective methods for the extraction of phytocannabinoids. Deep eutectic solvents (DESs) are an alternative to the use of hazardous organic solvents typically used in the industry. In this study, hydrophilic and hydrophobic DESs were developed based on terpenes, sugars, and natural organic acids as green extraction media for the extraction of cannabis bioactive compounds. The factors influencing the extraction of bioactive components, such as the type of DESs and extraction time, were investigated. Initial screening in hemp showed that the DES composed of Men: Lau (a 2:1-M ratio) had a greater extraction efficiency of cannabidiol (CBD) and cannabidiolic acid (CBDA) (11.07 ± 0.37 mg/g) of all the tested DESs and higher than ethanol. Besides having a higher or equivalent extraction yield as the organic solvents tested, DESs showed to be more selective, extracting fewer impurities, such as chlorophyll and waxes. These results, coupled with the non-toxic, biodegradable, low-cost, and environmentally friendly characteristics of DESs, provide strong evidence that DESs represent a better alternative to organic solvents.

Dioscorea spp.: Comprehensive Review of Antioxidant Properties and Their Relation to Phytochemicals and Health Benefits

Dioscorea, consisting of over 600 species, is the most important genus in the Dioscoreaceae family; however, the practically used plants, which are commonly called yam, are restricted to a remarkably smaller number of species. Numerous studies have reported the high nutritional value of yam, particularly as an alternative source of starch and some important micronutrients. Several Dioscorea species are widely used for various medicinal purposes as well. In many studies, the bioactivities and health benefits of Dioscorea extracts and other preparations have been related to the presence of phytochemicals, which possess antioxidant properties; they are related mainly to radical-scavenging capacity in chemical assays and positive effects on the endogenous antioxidant system in cell-based and in vivo assays. Considering the increasing number of publications on this topic and the absence of comprehensive and focused review papers on antioxidant potential, this article summarizes the results of studies on the antioxidant properties of Dioscorea spp. and their relation to phytochemicals and health benefits. A comprehensive survey of the published articles has revealed that the majority of studies have been performed with plant tubers (rhizomes, roots), while reports on leaves are rather scarce. In general, leaf extracts demonstrated stronger antioxidant potential than tuber preparations. This may be related to the differences in phytochemical composition: saponins, phenanthrenes and, for some pigment-rich species (purple yams), anthocyanins are important constituents in tubers, while phenolic acids and flavonoids are characteristic phytochemicals in the leaves. The review may assist in explaining ethnopharmacological knowledge on the health benefits of Dioscorea plants and their preparations; moreover, it may foster further studies of poorly investigated species, as well as their wider application in developing new functional foods and nutraceuticals.

Oriented Deep Eutectic Solvents as Efficient Approach for Selective Extraction of Bioactive Saponins from Husks of Xanthoceras sorbifolia Bunge

The husks of Xanthoceras sorbifolia Bunge (X. sorbifolia), as by-products of industrial production, have brought a severe burden to the environment and caused an enormous waste of resources. Bioactive triterpenoid saponins are rich in the husks. To reuse the husks and gain high-quality saponin products, saponin-oriented deep eutectic solvents (DESs), as an efficient and selective extraction strategy from X. sorbifolia husks, were designed for the first time. The enhancement of the extraction rate was investigated by screening solvents from acidic DESs and response surface methodology (RSM) optimization. As a result, the tetrapropylammonium bromide-lactic acid (TPMBr-La) was the most efficient DESs, with an extraction efficiency of up to 135% higher than 70% ethanol. A maximum extraction rate of 72.11 ± 0.61 mg Re/g dw was obtained under the optimized parameters. Scanning electron microscope graphs revealed that damage to the microstructure caused by DESs enhanced the extraction efficiency. Moreover, the recovery of total saponins with D101 macroporous resin was consistent with the pseudo-second-order kinetic model. Seven saponins were also identified by HPLC-MS analysis. Finally, TPMBr-La extracts exhibited 92.30 ± 1.10% DPPH radical scavenging rate at 100 μg/mL, and 92.20 ± 0.30% ABTS radical scavenging rate at 1200 μg/mL. Our current research proposes a selective and high-efficiency substitute for the extraction of saponins and might contribute to further DESs application in the recycling of by-products.

Determination of methomyl in grain using deep eutectic solvent-based extraction combined with fluorescence-based enzyme inhibition assays

A deep eutectic solvent (DES)-based extraction method is established to facilitate the determination of methomyl in grain via enzyme inhibition fluorescence. The environmentally-friendly DES was synthesized from proline and ethylene glycol and used as a green replacement for traditional extraction solvents that are generally toxic. The DES was added to grain samples and vortex extraction of methomyl, the supernatant was then collected for fluorescence detection. Biomass carbon quantum dots (CQDs) synthesized from millet were used as fluorescent probes. Acetylcholinesterase catalyzes the hydrolysis of acetylthiocholine iodide to thiocholine. The positively-charged thiocholine interacts electrostatically with the negatively-charged quantum dots resulting in the quenching of their fluorescent emission. The pesticide extract solution blocks the enzyme activity and thus recovers the fluorescent from the quantum dots. The fluorescence response was correlated with the amount of methomyl residue in the grain over the range 0.01 to 5 mg kg^-1. The limit of detection was found to be 0.003 mg kg^-1, and the limit of quantification 0.01 mg kg^-1. Recoveries of 86.5% to 107.8% were obtained using real samples, including millet, rice, wheat, and barley, with a relative standard deviation of less than 3.8%. The method is efficient and convenient and has good application prospects for extracting and detecting pesticides in grain samples.

DES Based Efficient Extraction Method for Bioactive Coumarins from Angelica dahurica (Hoffm.) Benth. & Hook.f. ex Franch. & Sav

In this study, a simple and environmentally friendly method was developed for the extraction of seven active coumarins from Angelica dahurica (Hoffm.) Benth. & Hook.f. ex Franch. & Sav.(A. dahurica) based on deep eutectic solvents (DESs). Among the 16 kinds of DES based on choline chloride, the DES system with the molar ratio of choline chloride, citric acid, and water as 1:1:2 had the best extraction effect. Ultrasonic-assisted response surface methodology (RSM) was used to investigate the optimal extraction scheme. The results showed that the optimal extraction conditions were a liquid–solid ratio of 10:1 (mL/g), an extraction time of 50 min, an extraction temperature of 59.85 °C, and a moisture content of 49.28%. Under these conditions, the extraction yield reached 1.18%. In addition, scanning electron microscopy (SEM) was used to observe the degree of powder fragmentation before and after extraction with different solvents. The cells of A. dahurica medicinal materials obtained by DES ultrasonic-assisted treatment were the most seriously broken, indicating that DES had the highest efficiency in the treatment of A. dahurica. The 1,1-diphenyl-2-picrylhydrazyl (DPPH) DPPH radical scavenging model was used to evaluate the biological activity of DES extract. The results showed that DES extract had better scavenging ability of DPPH free radical. Therefore, DES is a green solvent suitable for extracting coumarin compounds of A. dahurica, with great potential to replace organic solvents.

Stability of Chlorogenic Acid from Artemisiae Scopariae Herba Enhanced by Natural Deep Eutectic Solvents as Green and Biodegradable Extraction Media

A green and inexpensive natural deep eutectic solvent (NADES) was screened and integrated with an ultrasonic technique for extracting chlorogenic acid (CGA) from artemisiae scopariae herba. Response surface methodology was employed to investigate significant factors and optimize their influence. Proline-malic acid exhibited an excellent extraction capacity with a yield of 28.23 mg/g under the optimal conditions of water content of 15% (wt), solid-liquid ratio of 1.0/10 (g/mL), ultrasonic power of 300 W, and extraction time of 25 min. Simultaneously, the stability and antioxidant activity analysis exhibited a better performance of CGA in NADES than that in water and ethanol. The hydrogen-bonding interaction between CGA and natural deep eutectic molecules enhanced the stability and meanwhile protected the antioxidant activity of CGA.

Greener Is Better: First Approach for the Use of Natural Deep Eutectic Solvents (NADES) to Extract Antioxidants from the Medicinal Halophyte Polygonum maritimum L

In this study, natural deep eutectic solvents (NADES) formed by choline chloride (ChCl), sucrose, fructose, glucose, and xylose, were used to extract antioxidants from the halophyte Polygonum maritimum L. (sea knotgrass) and compared with conventional solvents (ethanol and acetone). NADES and conventional extracts were made by an ultrasound-assisted procedure and evaluated for in vitro antioxidant properties by the radical scavenging activity (RSA) on the 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical, oxygen radical absorbance capacity (ORAC), and copper chelating activity (CCA). Samples were profiled by liquid chromatography (LC)-electrospray ionization (ESI)-QTOF-MS analysis. ChCl:fructose was more efficient in the DPPH assay, than the acetone extract. ChCl:sucrose and ChCl:fructose extracts had the highest ORAC when compared with the acetone extract. NADES extracts had higher CCA, than the acetone extract. The phenolic composition of the NADES extracts was less complex than the conventional extracts, but the proportions of major antioxidants, such as flavonols and flavan-3-ols, were similar in all the solvents. Myricitrin was the major flavonoid in all of the samples, while gallic acid was the main phenolic acid in the conventional extracts and present in a greater amount in ChCl:fructose. Results suggest that NADES containing ChCl and sucrose/fructose can replace conventional solvents, especially acetone, in the extraction of antioxidants from sea knotgrass.

Efficacy of Natural Deep Eutectic Solvents for Extraction of Hydrophilic and Lipophilic Compounds from Fucus vesiculosus

The impact of the composition of natural deep eutectic solvents (NADES) and extraction conditions on the simultaneous extraction of hydrophilic ascorbic acid (AA), phlorotannins (TPhC), and lipophilic fucoxanthin (FX) from Fucus vesiculosus was investigated for the first time. In biological tests, the NADES extracts showed the promising ability to scavenge DPPH radicals. A positive correlation was observed between DPPH scavenging activity and AA, TPhC, and FX contents. We calculate the synergistic effect of antioxidants extracted by NADES from F. vesiculosus based on the mixture effect (ME). The addition of 30% water to the NADES and the prolongation of sonication time from 20 min up to 60 min were favorable for the ME. The ME for extracts with the NADES was increased by two folds (ME > 2). In contrast, conventional extraction by maceration with steering at 60 °C does not lead to the synergistic effect (ME = 1). It is notable that the NADES provides high stability and preserves the antioxidant activity of the extracts from F. vesiculosus during storage.