Deep Eutectic Solvents as Extraction Media for Valuable Flavonoids from Natural Sources

Recent Progress in Terrestrial Biota Derived Antibacterial Agents for Medical Applications

Conventional antibiotic and multidrug treatments are becoming less and less effective and the discovery of new effective and safe antibacterial agents is becoming a global priority. Returning to a natural antibacterial product is a relatively new current trend. Terrestrial biota is a rich source of biologically active substances whose antibacterial potential has not been fully utilized. The aim of this review is to present the current state-of-the-art terrestrial biota-derived antibacterial agents inspired by natural treatments. It summarizes the most important sources and newly identified or modified antibacterial agents and treatments from the last five years. It focuses on the significance of plant- animal- and bacteria-derived biologically active agents as powerful alternatives to antibiotics, as well as the advantages of utilizing natural antibacterial molecules alone or in combination with antibiotics. The main conclusion is that terrestrial biota-derived antibacterial products and substances open a variety of new ways for modern improved therapeutic strategies. New terrestrial sources of known antibacterial agents and new antibacterial agents from terrestrial biota were discovered during the last 5 years, which are under investigation together with some long-ago known but now experiencing their renaissance for the development of new medical treatments. The use of natural antibacterial peptides as well as combinational therapy by commercial antibiotics and natural products is outlined as the most promising method for treating bacterial infections. In vivo testing and clinical trials are necessary to reach clinical application.

3'-8″- Biflavones: A Review of Their Structural Diversity, Natural Occurrence, Role in Plants, Extraction and Identification

Dimeric forms of flavonoids, known as biflavonoids, are much less studied compared to monomeric forms. It is estimated that nearly 600 different natural biflavonoids have been described to date, containing various subtypes that can be subdivided according to the position of their combinations and the nature of the subunits. The group in which two monomers are linked by a 3'-8″-C atom includes the first isolated biflavonoid ginkgetin, derivatives of amentoflavone, and several other compounds. 3'-8″-biflavones recently attracted much attention as potential molecules with biological activity such as antiviral and antimicrobial activity and as effective molecules for the treatment of neurodegenerative and metabolic diseases and in cancer therapies. With the growing interest in them as pharmacologically active molecules, there is also increasing interest in finding new natural sources of 3'-8″-biflavones and optimizing methods for their extraction and identification. Herein, we have summarized the available data on the structural diversity, natural occurrence, role in plants, extraction, and identification of 3'-8″-biflavones.

Chemical-Functional Analysis of Extracts Obtained from Zuccagnia punctata Powder Using Green Solvents (NaDESs) in Conjunction with Traditional and Non-Traditional Techniques

Zuccagnia punctata Cav. (Family Fabaceae. Subfamily Caesalpinioideae) is a native plant species with a long history of use in Argentine traditional medicine. The purpose of the present study was to extract bioactive compounds with antioxidant and antifungal activity from Z. punctata aerial parts using conventional solvents (water, ethanol 60°, vegetal oil) and unconventional solvents (natural deep eutectic solvents or NaDESs) such as green solvents with and without the assistance of ultrasound (UAE) and microwaves (MAE). NaDESs such as glucose: lactic acid (LGH), sucrose: citric acid (CAS), choline chloride: urea (CU) and glucose: fructose: sucrose (FGS) were used. LGH and CU were effective in the extraction of phenolic compounds (6710 ± 10.12 µg GAE/mL and 7140 ± 15.00 µg GAE/mL, respectively) as well as ethanol (6270 µg ± 12.00 µg GAE/mL) using conventional methods. Two chemical markers of Z. punctata (2',4'-dihydroxychalcone and 2',4'-dihydroxy -3-methoxychalcone) were extracted in a high proportion in ethanol, oil, LGH and CU with UAE. The ABTS antioxidant capacity was higher in the extracts obtained with LGH and CU (SC50: 0.90 ± 0.10 µg GAE/mL and 1.08 ± 0.16 µg GAE/mL, respectively). The extract obtained with vegetal oil was the most potent as antifungal, followed by the extracts in ethanol, LGH and CU. These findings highlight the importance of using environmentally friendly solvents such as NaDESs to obtain bioactive metabolites from Z. punctata, an endemic plant of Argentina with a potential application in the food, cosmetic and pharmaceutical industries.

Application of eco-friendly natural deep eutectic solvents (NADES) in HPLC for separation of complex natural products: Current limitations and future directions

Natural deep eutectic solvents (NADES) have been used in chromatography as extraction media and HPLC mobile phase additives, but only once have they been used as HPLC major mobile phase component. This review illustrates current knowledge and major limitations on use of NADES in HPLC mobile phase as well as to propose possible NADES may be ready for use as HPLC mobile phases and the detectors they can be used with. High viscosity is one of the major roadblocks encountered when using NADES as a mobile phase component in HPLC regardless of detectors employed. A comprehensive review of published literature was conducted to identify articles that focused on using NADES as extraction solvents for natural products, particularly polyphenols or reported NADES viscosities to establish a database of NADES which could be used as HPLC mobile phases under various conditions. Other identified challenges that limit NADES application in HPLC mobile phase include low volatility, NADES wavelength cutoff (UV and Fluorescent detectors) and impurities. Methods for overcoming these limitations are discussed so that NADES may be more integrated into HPLC systems in the future.

Enhancing deep eutectic solvent systems for efficient fermentable sugar recovery from lignocellulosic fiber

Efficient conversion of sugars into fermentable sugars is a critical challenge in the cost-effective production of lignocellulosic biopolymers and biofuels. This study focuses on various sugar quantification techniques applied to Furcraea Foetida (Mauritius Hemp) samples, utilizing natural deep eutectic solvents (NADES) and deep eutectic solvents (DES) like urea, glycerol, citrates, pyrogallol (PY), and cetyltrimethylammonium bromide (CTAB). Employing a Taguchi-designed experiment, operational conditions were fine-tuned to evaluate the influence of time, concentration, and temperature on each deep eutectic solvent-based process. The emerging green solvent extraction approach demonstrated significant results, achieving notably high sugar yields compared to traditional techniques such as alkali, hot-water, and acid-mediated extraction. At a CTAB:PY molar ratio of 1:3, optimized for 60 min at 50 °C, the highest fermentable sugar (FS) yield of 0.6891 ± 0.0123 g FS/g LCB was attained-2 to 6 times higher than non-optimized values and 0.2 to 0.3 times higher than optimized traditional methods. In light of this, this research study emphasizes the pivotal significance of efficient sugar conversion through optimized deep eutectic solvent-based extraction methods, with a particular focus on Furcraea Foetida fibers, offering promising outcomes for the biofuel and biopolymer production industry.

Deep eutectic solvent-based shaking-assisted extraction for determination of bioactive compounds from Norway spruce roots

Polyphenolic compounds play an essential role in plant growth, reproduction, and defense mechanisms against pathogens and environmental stresses. Extracting these compounds is the initial step in assessing phytochemical changes, where the choice of extraction method significantly influences the extracted analytes. However, due to environmental factors, analyzing numerous samples is necessary for statistically significant results, often leading to the use of harmful organic solvents for extraction. Therefore, in this study, a novel DES-based shaking-assisted extraction procedure for the separation of polyphenolic compounds from plant samples followed by LC-ESI-QTOF-MS analysis was developed. The DES was prepared from choline chloride (ChCl) as the hydrogen bond acceptor (HBA) and fructose (Fru) as the hydrogen bond donor (HBD) at various molar ratios with the addition of 30% water to reduce viscosity. Several experimental variables affecting extraction efficiency were studied and optimized using one-variable-at-a-time (OVAT) and confirmed by response surface design (RS). Nearly the same experimental conditions were obtained using both optimization methods and were set as follows: 30 mg of sample, 300 mg of ChCl:Fru 1:2 DES containing 30% w/w of water, 500 rpm shaking speed, 30 min extraction time, 10°C extraction temperature. The results were compared with those obtained using conventional solvents, such as ethanol, methanol and water, whereby the DES-based shaking-assisted extraction method showed a higher efficiency than the classical procedures. The greenness of the developed method was compared with the greenness of existing procedures for the extraction of polyphenolic substances from solid plant samples using the complementary green analytical procedure index (ComplexGAPI) approach, while the results for the developed method were better or comparable to the existing ones. In addition, the practicability of the developed procedure was evaluated by application of the blue applicability grade index (BAGI) metric. The developed procedure was applied to the determination of spruce root samples with satisfactory results and has the potential for use in the analysis of similar plant samples.

Predicting the formation of NADES using a transformer-based model

The application of natural deep eutectic solvents (NADES) in the pharmaceutical, agricultural, and food industries represents one of the fastest growing fields of green chemistry, as these mixtures can potentially replace traditional organic solvents. These advances are, however, limited by the development of new NADES which is today, almost exclusively empirically driven and often derivative from known mixtures. To overcome this limitation, we propose the use of a transformer-based machine learning approach. Here, the transformer-based neural network model was first pre-trained to recognize chemical patterns from SMILES representations (unlabeled general chemical data) and then fine-tuned to recognize the patterns in strings that lead to the formation of either stable NADES or simple mixtures of compounds not leading to the formation of stable NADES (binary classification). Because this strategy was adapted from language learning, it allows the use of relatively small datasets and relatively low computational resources. The resulting algorithm is capable of predicting the formation of multiple new stable eutectic mixtures (n = 337) from a general database of natural compounds. More importantly, the system is also able to predict the components and molar ratios needed to render NADES with new molecules (not present in the training database), an aspect that was validated using previously reported NADES as well as by developing multiple novel solvents containing ibuprofen. We believe this strategy has the potential to transform the screening process for NADES as well as the pharmaceutical industry, streamlining the use of bioactive compounds as functional components of liquid formulations, rather than simple solutes.

Toxicity test profile for deep eutectic solvents: A detailed review and future prospects

Deep eutectic solvents (DESs) are preferable in terms of starting materials, storage and synthesis, simplicity, and component material affordability. In several industries ranging from chemical, electrochemical, biological, biotechnology, material science, etc., DES has demonstrated remarkable potential. Despite all these accomplishments, the safety issue with DES must be adequately addressed. Different DES interacts with the cellular membranes differently. It is not possible to classify all DES as easily biodegradable. By expanding the current understanding of the toxicity and biodegradation of DES, interactions between organisms and cellular membranes can be linked. The DES toxicity profile varies according to their concentration, the nature of the individual components, and how they interact with living things. Therefore, the results of this review can serve as a baseline for DES development in the future.

A Sustainable Extraction Approach of Phytochemicals from Date (Phoenix dactylifera L.) Fruit Cultivars Using Ultrasound-Assisted Deep Eutectic Solvent: A Comprehensive Study on Bioactivity and Phenolic Variability

The present study aimed to evaluate the efficacy of natural deep eutectic solvents (NADESs) on the extraction of phytochemicals from eight Algerian date fruit cultivars (Phoenix dactylifera L.). In this study, lactic acid/sucrose-based NADESs were used as an alternative to conventional chemical solvents using the ultrasound-assisted extraction (UAE) method. The obtained extracts were assessed for the determination of bioactive compound contents, phenolic composition, antioxidant activity, and enzyme inhibitory potential. The results showed a considerable variation in phytochemical compositions and related activities between cultivars, where the greatest contents of total phenolics (1288.7 mg GAE/100 g), total flavonoids (53.8 mg QE/100 g), proanthocyanidins (179.5 mg CE/g), and total triterpenoids (12.88 mg OAE/100 g) were detected in the fruits of the Ourous cultivar. The same cultivar displayed the highest antioxidant capacity against DPPH• free radical (595 mg AAE/100 g), ABTS•+ cation radical (839 mg TE/100 g), and ferric reducing antioxidant potential (704 mg AAE/100 g). All extracts manifested moderate antioxidant activities tested by phosphomolybdenum, NO•, and linoleic acid lipid peroxidation assays. These extracts also exhibited interesting levels of in vitro enzyme inhibition; the Ourous cultivar gave the best inhibitory activity against α-amylase and acetylcholinesterase with 45 and 37%, respectively. HPLC-DAD-MS detected a total of five compounds, with phenolic acids and flavonoids being the main phenolics identified in the extract. The phenolic composition exhibited significant variability among cultivars. Notably, the highest amounts were revealed in the Tazizaout cultivar, with the predominance of gallic acid. The results confirmed that the combination of UAE and NADESs provides a novel and important alternative to chemical solvents for sustainable and environmentally friendly extraction and can represent a good alternative in food and pharmaceutical industry applications.

A Comprehensive Review on Deep Eutectic Solvents and Its Use to Extract Bioactive Compounds of Pharmaceutical Interest

The extraction of bioactive compounds of pharmaceutical interest from natural sources has been significantly explored in recent decades. However, the extraction techniques used were not very efficient in terms of time and energy consumption; additionally, the solvents used for the extraction were harmful for the environment. To improve the environmental impact of the extractions and at the same time increase the extraction yields, several new extraction techniques were developed. Among the most used ones are ultrasound-assisted extraction and microwave-assisted extraction. These extraction techniques increased the yield and selectivity of the extraction in a smaller amount of time with a decrease in energy consumption. Nevertheless, a high volume of organic solvents was still used for the extraction, causing a subsequent environmental problem. Neoteric solvents appeared as green alternatives to organic solvents. Among the neoteric solvents, deep eutectic solvents were evidenced to be one of the best alternatives to organic solvents due to their intrinsic characteristics. These solvents are considered green solvents because they are made up of natural compounds such as sugars, amino acids, and carboxylic acids having low toxicity and high degradability. In addition, they are simple to prepare, with an atomic economy of 100%, with attractive physicochemical properties. Furthermore, the huge number of compounds that can be used to synthesize these solvents make them very useful in the extraction of bioactive compounds since they can be tailored to be selective towards a specific component or class of components. The main aim of this paper is to give a comprehensive review which describes the main properties, characteristics, and production methods of deep eutectic solvents as well as its application to extract from natural sources bioactive compounds with pharmaceutical interest. Additionally, an overview of the more recent and sustainable extraction techniques is also given.

A green method to extract rutin from Sophora japonica L

Sophora japonica L. contains high levels of rutin, which has great potential for use in pharmaceutical products for the treatment of diseases related to the cardiovascular and circulatory systems. We proposed a method of extracting rutin from S. japonica by using a green solvent.•Green deep eutectic solvents (DESs) of choline chloride and ethylene glycol (ChCl-Eth) showed the highest extraction efficiency of rutin from S. japonica.•Under optimal conditions, the extraction yield of ChCl-Eth was 1.34 times higher than that of methanol as solvent.•Rutin was recovered from the DES extracts using water as the antisolvent with a high recovery yield, and the DESs of ChCl-Eth could be productively recovered and reused at least 3 times.

Recovery of Polyphenols from Rosehip Seed Waste Using Natural Deep Eutectic Solvents and Ultrasonic Waves Simultaneously

Rosehips are processed and consumed in numerous forms, such as juice, wine, herbal tea, yogurt, preserved fruit, and canned products. The seeds share in fruit is 30-35% and they have recently been recognized as an important source of oil rich in unsaturated fatty acids. However, after defatting, seed waste may still contain some polar polyphenolic compounds, which have been scarcely investigated. The aim of this study was to examine the potential of the defatted seed waste as a source of polyphenols. For the defatting process, supercritical carbon dioxide extraction at 300 bar and 40 °C was applied. The capacity of eight different natural deep eutectic solvents (NADES) for the recovery of phenolics from defatted rosehip seed powder (dRSP) was examined. In the extracts obtained with ultrasound-assisted NADES extraction, twenty-one phenolic compounds were identified with LC-MS/MS, among which the most abundant were quinic acid (22.43 × 103 µg/g dRSP) and catechin (571.93 µg/g dRSP). Ternary NADES formulations based on lactic acid proved to be superior. Potential correlations between identified chemical compounds, solvent polarity and viscosity, as well as the compound distributions across studied solvent combinations in PCA hyperspace, were also investigated. PCA demonstrated that more polar NADES mixtures showed improved extraction potential. The established environmentally friendly process represents an approach of transforming rosehip seed waste into value-added products with the potential to be applied in the food industry and to contribute to sustainable production.

Quercetin 3-O-Glucuronide from Aglianico Vine Leaves: A Selective Sustainable Recovery and Accumulation Monitoring

In recent years, as part of sustainable development policies, the revaluation of end-of-life products has become more and more widespread. In terms of sustainability, in a scenario of circular economy food sustainability aims, inter alia, at making an effective re-use of natural resources as a starting point for the obtainment of high added-value products. With the aim of promoting the valorization of the wine sector wastes, the present study took into account the leaves of Vitis vinifera L. cv. Aglianico from the Campania Region (Italy). The use of deep eutectic solvents as a greener alternative to the most common organic solvents, joint to ultrasound-assisted maceration, and LC-MS tools, allowed us to define for the first time a six-month quantitative variation of flavonol derivatives, and in particular of quercetin 3-O-glucuronide, based on the collection time and the leaf height on the grapevine. Results underlined that the influence of abiotic factors, such as exposure to sunlight, which is pivotal in the biosynthesis of such compounds, should be strictly considered for their full recovery.

Toward the bioactive potential of myricitrin in food production: state-of-the-art green extraction and trends in biosynthesis

Myricitrin is a member of flavonols, natural phenolic compounds extracted from plant resources. It has gained great attention for various biological activities, such as anti-inflammatory, anti-cancer, anti-diabetic, as well as cardio-/neuro-/hepatoprotective activities. These effects have been demonstrated in both in vitro and in vivo models, making myricitrin a favorable candidate for the exploitation of novel functional foods with potential protective or preventive effects against diseases. This review summarized the health benefits of myricitrin and attempted to uncover its action mechanism, expecting to provide a theoretical basis for their application. Despite enormous bioactive potential of myricitrin, low production, high cost, and environmental damage caused by extracting it from plant resources greatly constrain its practical application. Fortunately, innovative, green, and sustainable extraction techniques are emerging to extract myricitrin, which function as alternatives to conventional techniques. Additionally, biosynthesis based on synthetic biology plays an essential role in industrial-scale manufacturing, which has not been reported for myricitrin exclusively. The construction of microbial cell factories is absolutely an appealing and competitive option to produce myricitrin in large-scale manufacturing. Consequently, state-of-the-art green extraction techniques and trends in biosynthesis were reviewed and discussed to endow an innovative perspective for the large-scale production of myricitrin.

Enhanced extraction of phenolic compounds from mango by-products using deep eutectic solvents

Deep eutectic solvents (DESs) potential for the extraction of polyphenolic compounds (PC) from mango by-products (peel and seed) was evaluated. Ultrasound (US) and agitation were applied to evaluate the effects of solvent and extraction methodology. The extracts were characterized with antioxidant capacity and HPLC-DAD profile. A theoretical study was performed using density functional theory and the QTAIM approach. β-alanine and choline chloride based DESs were effective to extract PC from peel and seed. Some DES increased PC extraction up to three times for peel (23.05 ± 1.22 mg/g DW) and up to five time for seeds (60.01 ± 1.40 mg/g DW). The PC profile varied with the solvent (DES vs EtOH/MeOH), procedure (US vs agitation) and material (peel or seed). Mangiferin extraction from peels was significantly increased with β-alanine based DES (676.08 ± 20.34 μg/gDW). The strength of H-bonds had a determining effect on the viscosity of DESs. The solute-solvent solvation energy was suitable to estimate the strength of H-bond interactions between DES and target compounds. This study demonstrates the remarkable capacity of DESs to extract PC from mango by-products and provides insights into the factors controlling extraction properties.

Comparison of Different Green Extraction Techniques Used for the Extraction of Targeted Flavonoids from Edible Feijoa (Acca sellowiana (O.Berg) Burret) Flowers

This study aimed to investigate the effect of four green extraction techniques (ultrasound-assisted extraction, UAE; supercritical fluid extraction, SFE; subcritical water extraction, SWE; and extraction using deep eutectic solvents, DES) on the extraction of targeted flavonoids from edible feijoa flowers. The bioactive components in the obtained extracts were quantified by High-Performance Liquid Chromatography-Photodiode Array Detector (HPLC-PDA). Moreover, total polyphenol content and antioxidant activity by DPPH^•, ABTS^•+, FRAP, and CUPRAC assays were investigated. UAE generally gave the highest yields for isoquercitrin and quercetin content (18.36-25.33 and 10.86-16.13 µg/g), while DES extraction with choline chloride:lactic acid (1:2) and H₂O content of 50% gave the highest yield of chrysanthemin (90.81 µg/g). The highest yield of flavone (12.69 mg/g) was obtained with supercritical CO₂ at 300 bar. Finally, UAE gave the highest total polyphenol content (ca. 64 mg GAE/g) and antioxidant activity at 70 °C during 30 min with 40% (0.84 mmol TEAC/g and 2.25 mmol Fe²⁺/g, for ABTS^•+ and CUPRAC, respectively) and 60% ethanol-water solution (0.49 mmol TEAC/g and 2.09 mmol Fe²⁺/g, for DPPH^• and FRAP, respectively). The eco-friendly extraction techniques resulted in selective methods capable of extracting targeted bioactive compounds from edible feijoa flowers.

From Foxtail Millet Husk (Waste) to Bioactive Phenolic Extracts Using Deep Eutectic Solvent Extraction and Evaluation of Antioxidant, Acetylcholinesterase, and α-Glucosidase Inhibitory Activities

Foxtail millet husk (FMH) is generally removed and discarded during the first step of millet processing. This study aimed to optimize a method using deep eutectic solvents (DESs) combined with ultrasonic-assisted extraction (UAE) to extract phenols from FMH and to identify the phenolic compositions and evaluate the biological activities. The optimized DES comprised L-lactic acid and glycol with a 1:2 molar ratio by taking the total flavonoid content (TFC) and total phenolic content (TPC) as targets. The extraction parameters were optimized to maximize TFC and TPC, using the following settings: liquid-to-solid ratio of 25 mL/g, DES with water content of 15%, extraction time of 41 min and temperature of 51 °C, and ultrasonic power at 304 W. The optimized UAE-DES, which produced significantly higher TPC, TFC, antioxidant activity, α-glucosidase, and acetylcholinesterase inhibitory activities compared to conventional solvent extraction. Through UPLC–MS, 12 phenolic compounds were identified, with 1-O-p-coumaroylglycerol, apigenin-C-pentosyl-C-hexoside, and 1-O-feruloyl-3-O-p-coumaroylglycerol being the main phenolic components. 1-O-feruloyl-3-O-p-coumaroylglycerol and 3,7-dimethylquercetin were identified first in foxtail millet. Our results indicated that FMH could be exploited by UAE-DES extraction as a useful source of naturally derived antioxidants, along with acetylcholinesterase and α-glucosidase inhibitory activities.

Enhanced Recovery of Natural Antioxidants from Grape Waste Using Natural Eutectic Solvents-Based Microwave-Assisted Extraction

The evaluation of sustainable solvents as alternatives to more harmful conventional solvents combined with intensification techniques to recover phenolic compounds from agri-food waste is in the spotlight. The wine industry generates large amounts of waste as a consequence of grape processing operations, which can be revalued by solvent extraction of valuable antioxidants for food and fine chemical applications. Therefore, the present study focuses on the use of natural eutectic solvents (NAESs) with benign environmental, health, and safety profiles, for valorization of grape waste in the context of a circular economy. Herein, up to 15 NAESs consisting of combinations of three hydrogen bond acceptors (choline chloride, L-proline, and betaine) and four hydrogen bond donors (1,2-propanediol, glycerol, and 1,2- and 1,3-butanediol) were evaluated for antioxidant recovery. After an initial screening of the performance of NAESs by conventional extraction, the process was intensified by microwave-assisted extraction (MAE). The extracts were analyzed by UV/VIS spectrophotometric and HPLC methods. Promising results were obtained with the solvent betaine, 1,2-butanediol [1:4], using MAE at 100 °C for 3 min. Overall, the proposed NAESs-based MAE method was successfully applied to recover target compounds from grape waste, with great prospects for the antioxidants market and sustainable development for the winery sector.

Extraction of Bioactive Compounds from C. vulgaris Biomass Using Deep Eutectic Solvents

C. vulgaris microalgae biomass was employed for the extraction of valuable bioactive compounds with deep eutectic-based solvents (DESs). Particularly, the Choline Chloride (ChCl) based DESs, ChCl:1,2 butanediol (1:4), ChCl:ethylene glycol (1:2), and ChCl:glycerol (1:2) mixed with water at 70/30 w/w ratio were used for that purpose. The extracts' total carotenoid (TCC) and phenolic contents (TPC), as well as their antioxidant activity (IC50), were determined within the process of identification of the most efficient solvent. This screening procedure revealed ChCl:1,2 butanediol (1:4)/H₂O 70/30 w/w as the most compelling solvent; thus, it was employed thereafter for the extraction process optimization. Three extraction parameters, i.e., solvent-to-biomass ratio, temperature, and time were studied regarding their impact on the extract's TCC, TPC, and IC50. For the experimental design and process optimization, the statistical tool Response Surface Methodology was used. The resulting models' predictive capacity was confirmed experimentally by carrying out two additional extractions under conditions different from the experimental design.

"Novel chitosan/alginate hydrogels as carriers of phenolic-enriched extracts from saffron floral by-products using natural deep eutectic solvents as green extraction media"

The current saffron production system is generating several hundreds of tons of tepal waste, because only stigmas are used for food. Consequently, the valorization of saffron floral by-products by developing stable functional ingredients could lead to the environmental impact minimization. Thus, the main aim of this study was to develop innovative green extraction processes from saffron floral by-products by using Natural Deep Eutectic Solvents (NaDES) and ultrasound-assisted extraction (UAE) as ecological extraction method. Response surface methodology was used to optimize process parameters. To improve the stability of the optimal extracts, they were incorporated into chitosan/alginate hydrogels, studying their water-uptake and water retention capacity and the total phenolic content (TPC) during the in vitro digestion. The results indicated that the optimal extraction, regarding total phenolic and flavonoid content, was achieved in 20 min, using 180 W ultrasound power and 90% of NaDES. The results of the DPPH assay revealed the potent antioxidant activity of saffron floral by-products. The chitosan/alginate hydrogels incorporating the as-obtained NaDES extracts showed favorable properties whereas the TPC remained stable under intestinal conditions. Therefore, NaDES combined with UAE was an efficient technique to isolate high added-value compounds from saffron flowers, succeeding also the valorization of discarded waste by using green and low-cost strategies. Furthermore, these novel hydrogels could be used as promising candidates for food or cosmetic applications.

Macroporous adsorptive resin-assisted enrichment of polyphenol from Psidium guajava leaves improved its in vitro antioxidant and anti-hemolytic properties

Phytochemical analyses of guava leaf extracts, commonly applied in traditional medicine, revealed the presence of several bioactive polyphenols. In this study, we optimized the enrichment of total polyphenol from Guava leaf ethanolic extract (GEE) using six macroporous adsorptive resins (MAR) including AB8, D101, X5, ADS17, S400, and AD7. Also investigated are the contributions of adsorption time, extract concentration, pH, elution time, and eluent ethanol concentrations on the polyphenol enrichment potential of MAR. The antioxidant and anti-hemolytic properties of the crude and polyphenol-rich extracts were determined. Our results indicate that treatment of GEE extract with AB8 MAR at a concentration of 15 mg GEE/g resin, adsorption time of 45 min, elution time of 40 min, and eluent ethanol concentration of 50% (v/v) improved the flavonoids and phenol concentration of GEE by 2 and 2.5 folds respectively. The DPPH radical scavenging, ferric reducing ability of the plasma (FRAP), anti-hemolytic and anti-peroxidation activity of the resultant polyphenol-rich extracts improved by 1.5, 1.6, 1.4, and 1.88 folds respectively, when compared to the crude extract. Our work shows that the MAR-assisted enrichment operation is a rapid, feasible, and economical strategy for enriching bioactive polyphenols from guava leaf extracts.

Applications of Deep Eutectic Solvents in Sample Preparation and Extraction of Organic Molecules

The use of deep eutectic solvents (DES) is on the rise worldwide because of the astounding properties they offer, such as simplicity of synthesis and utilization, low-cost, and environmental friendliness, which can, without a doubt, replace conventional solvents used in heaps. In this review, the focus will be on the usage of DES in extracting a substantial variety of organic compounds from different sample matrices, which not only exhibit great results but surpass the analytical performance of conventional solvents. Moreover, the properties of the most commonly used DES will be summarized.

The Lebanese Red Algae Jania rubens: Promising Biomolecules against Colon Cancer Cells

Colorectal cancer (CRC) is ranked the second most lethal type of tumor globally. Thus, developing novel anti-cancer therapeutics that are less aggressive and more potent is needed. Recently, natural bioactive molecules are gaining interest as complementary and supportive antineoplastic treatments due to their safety, effectiveness, and low cost. Jania rubens (J. rubens) is a red coral seaweed abundant in the Mediterranean and bears a significant pharmacological essence. Despite its therapeutic potential, the natural biomolecules extracted from this alga are poorly identified. In this study, the proximal analysis revealed high levels of total ash content (66%), 11.3% proteins, 14.5% carbohydrates, and only 4.5% lipids. The elemental identification showed magnesium and calcium were high among its macro minerals, (24 ± 0.5 mg/g) and (33 ± 0.5 mg/g), respectively. The Chlorophyll of J. rubens was dominated by other pigments with (0.82 ± 0.02 mg/g). A 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical scavenging assay identified effective antioxidant activity in various J. rubens extracts. More importantly, a 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) tetrazolium reduction and wound healing assays indicate that organic extracts from J. rubens significantly counteract the proliferation of colon cancer cell lines (HCT-116 and HT-29) and inhibit their migratory and metastatic properties in a dose and time-dependent manner. Overall, this study provides insight into the physicochemical properties of red seaweed, J. rubens, and identifies its significant antioxidant, cytotoxic, and anti-migratory potential on two colorectal cell lines, HCT-116 and HT-29.

Efficiency of Natural Deep Eutectic Solvents to Extract Phenolic Compounds from Agrimonia eupatoria: Experimental Study and In Silico Modelling

To replace common organic solvents that present inherent toxicity and have high volatility and to improve the extraction efficiency, a range of natural deep eutectic solvents (NADESs) were evaluated for the extraction of phenolic compounds from Agrimonia eupatoria. Screening of NADES efficiency was carried out based on the total phenolic and flavonoid content and radical-scavenging activity, determined by spectrophotometry, as well as phenolic compounds quantified, obtained using ultra-high-performance liquid chromatography with a diode array detector and a triple-quadrupole mass spectrometer. Increased extraction efficiency when compared with organic solvent was achieved using NADES mixtures choline chloride (ChCl):urea 1:2 and choline chloride:glycerol 1:1. Flavonol glycosides were the most abundant compounds in all extracts. The COSMO-RS model provided insights into the most important intermolecular interactions that drive the extraction process. Moreover, it could explain the extraction efficiency of flavonol glycosides using ChCl:glycerol NADES. The current article offers experimental evidence and mechanistic insights for the selection of optimal NADES to extract bioactive components from Agrimonia eupatoria.

Separation and Purification of Astragalus membranaceus Polysaccharides by Deep Eutectic Solvents-Based Aqueous Two-Phase System

(1) Background: Aqueous two-phase systems (ATPSs) have been widely used in the separation and purification of bioactive substances in recent years. (2) Methods: In this study, deep eutectic solvents (DESs)-based ATPSs were employed for the extraction and separation of Astragalus membranaceus polysaccharides (AMP). The optimal DES (choline chloride:urea = 1:1) was first screened to extract AMP, and the effect of DES concentration, solid-liquid ratio, pH, extraction temperature, and extraction time on the extraction yield of AMP were investigated. (3) Results: The maximum extraction yield was 141.11 mg/g under the optimum conditions. AMP was then preliminarily purified by ATPS, to further realize the recycling and reuse of DES. The effect of type of salts, salt concentration, and extraction temperature on extraction efficiency was investigated. The extraction efficiency was 97.85% for AMP under the optimum ATPS conditions. Finally, the obtained AMP was studied by molecular weight determination, infrared spectroscopy analysis, and monosaccharide composition analysis. (4) Conclusions: This ATPS extraction based on DESs is simple, environmentally friendly, low-cost, and has high extraction efficiency, which provides new ideas for the extraction of plant polysaccharides and other bioactive compounds.

Response surface modeling and optimization of the extraction conditions using lactic acid-based deep eutectic solvents as green alternative extraction media for Mentha pulegium

INTRODUCTION

Most recurrently available organic solvents are toxic and inflammable and pose high risks to human health. Natural deep eutectic solvents (NADESs) have been developed as promising green alternatives.

OBJECTIVE

We aimed to extract polyphenolic compounds from Mentha pulegium using lactic acid-based deep eutectic solvents. Extraction parameters were optimized by response surface methodology.

MATERIAL AND METHODS

Combined with ultrasound-assisted extraction, three different lactic acid-based deep eutectic solvents were investigated for the extraction of polyphenols. Methanol (80%, v/v) was used for comparison. The optimized influencing factors were: water content in solvent, extraction time, and temperature. The design was adopted including 17 experiments with three center points.

RESULTS

All NADESs tested showed an excellent extraction efficacy compared to 80% methanol. Under the optimized conditions, with 45% of water, at 30°C, and for extraction 90 min, the highest extraction yields were recorded using lactic acid:sodium acetate (3:1), achieving 173.35 ± 0.02 mg gallic acid equivalents (GAE)/g dry weight (dw) of polyphenols and 95 ± 0.09% antioxidant activity. After extraction for 90 min at 80°C with 18% of water, we obtained 164.06 ± 0.01 mg GAE/g dw and 94 ± 0.02% antioxidant activity using lactic acid:glucose (5:1). Efficient recovery (64.92 ± 0.01 mg GAE/g dw and 97 ± 0.1% antioxidant activity) was achieved using lactic acid:glycine (3:1) with 31% of water, at 35°C, and extraction for 30 min.

CONCLUSION

Our results indicate that with optimized parameters, the proposed natural solvents are excellent alternatives to chemical ones for the extraction of phenolic compounds.

Hesperidin: A Review on Extraction Methods, Stability and Biological Activities

Hesperidin is a bioflavonoid occurring in high concentrations in citrus fruits. Its use has been associated with a great number of health benefits, including antioxidant, antibacterial, antimicrobial, anti-inflammatory and anticarcinogenic properties. The food industry uses large quantities of citrus fruit, especially for the production of juice. It results in the accumulation of huge amounts of by-products such as peels, seeds, cell and membrane residues, which are also a good source of hesperidin. Thus, its extraction from these by-products has attracted considerable scientific interest with aim to use as natural antioxidants. In this review, the extraction and determination methods for quantification of hesperidin in fruits and by-products are presented and discussed as well as its stability and biological activities.

Extraction of Polyphenolic Antioxidants from Red Grape Pomace and Olive Leaves: Process Optimization Using a Tailor-Made Tertiary Deep Eutectic Solvent

In the framework of introducing green strategies for food processing, the industrial orientation has shifted towards the replacement of conventional petroleum-based solvents with alternative eco-friendly ones. On this basis, the objective of this study was to synthesize a novel, tertiary, food-grade deep eutectic solvent, composed of glycerol, citric acid, and L-proline (GL-CA-Pro), and to test it as a solvent for the extraction of polyphenols from agri-food waste biomass. After an initial screening on various common residual materials (apple peels, lemon peels, orange peels, red grape pomace, olive leaves), evidence emerged that indicated GL-CA-Pro was more effective than other DESs commonly used for polyphenol extraction. Furthermore, extracts from red grape pomace (RGP) and olive leaves (OLL) were shown to contain higher level of total polyphenols and increased antioxidant activity. Process optimization for those two materials with the response surface methodology revealed that the major difference pertained to the extraction time. In addition, for both materials, GL-CA-Pro was shown to provide higher total polyphenol yields (53.25 and 42.48 mg gallic acid equivalents per g of dry mass, respectively) compared to water and 60% aqueous ethanol. However, the chromatographic analyses for OLL suggested aqueous ethanol was a more suitable solvent for some principal polyphenolic constituents. The RGP extract produced with GL-CA-Pro exhibited significantly stronger antioxidant effects compared to the aqueous and hydroethanolic extracts, but the outcome for the OLL extracts was diversified. It was concluded that GL-CA-Pro is a very efficient solvent for RGP polyphenols, but its efficiency regarding OLL was comparable to that of aqueous ethanol.

Kinetics and mechanism of Eu(III) transfer in tributyl phosphate microdroplet/HNO3 aqueous solution system revealed by fluorescence microspectroscopy

In this study, we reveal an Eu(III) extraction mechanism at the interface between HNO₃ and tributyl phosphate (TBP) solutions using fluorescence microspectroscopy. The mass transfer rate constant at the interface is obtained from the analysis of fluorescence intensity changes during the forward and backward extractions at various HNO₃ and TBP concentrations to investigate the reaction mechanism. This result indicates that one nitrate ion reacts with Eu(III) at the interface, whereas TBP molecules are not involved in the interfacial reaction, which is different from the results obtained using the NaNO₃ solution in our previous study. We demonstrate that the chemical species of Eu(III) complex with nitrate ion and TBP in the aqueous solution play an important role for the extraction mechanism. The rate constants of the interfacial reactions in the forward and backward extractions are (4.0-5.0) × 10^-7 m M^-1 s^-1 and (3.2-3.3) × 10^-6 m s^-1, respectively. We expect that our revealed mechanism provides useful and fundamental knowledge for actual solvent extraction.

Infrared assisted extraction of bioactive compounds from plant materials: Current research and future prospect

The extraction of bioactive compounds from plant materials has attracted much attention due to their potential therapeutic effects. This article reviews the basic principles, characteristics, and recent applications of infrared assisted extraction (IAE) of bioactive compounds from plant materials. The advantages and disadvantages of IAE are considered, and operation mode and technological improvements, processes, solvents used and other future developments are identified. The review indicated that IAE was a simple, rapid, and cost-effective technique with the capacity for industrial scale application. Future research should focus on energy consumption reduction, green chemistry extraction processes, simplified operation steps, intelligent extraction process, and the establishment of kinetic and thermodynamic models. This article provides a comprehensive understanding of the principles and applications of IAE for the preparation of bioactive compounds, which will be of benefit to researchers and users of the technology.

Extraction of curcumin from turmeric residue (Curcuma longa L.) using deep eutectic solvents and surfactant solvents

Using waste materials to extract biologically active ingredients with green solvents is a new trend for sustainable development. Herein, different types of deep eutectic solvents (DESs) and surfactant solvents (SSs) were used to extract curcumin from turmeric residues (TRs), among which choline chloride-propylene glycol (ChCl-Pro) showed the highest yield. The optimized extraction conditions included a ChCl : Pro ratio of 1 : 2, water content in the DESs of 20%, solid : liquid ratio of 1 : 40 maintained for 60 min at 50 °C, and a TR particle size of 0.18 mm. The extraction yield was 54.2 mg g^-1, which was 1.31 times higher than when methanol was used as a solvent. Distilled water was used to recover curcumin from the DES extract with a recovery yield of 99.7%. Furthermore, the antioxidant and acetylcholinesterase (AChE) inhibitory activities of the recovered curcumin were evaluated, with IC₅₀ values of 25.58 ± 0.51 and 19.12 ± 0.83 μg mL^-1, respectively. This study highlights the promising potential of using green solvents to extract bioactive compounds from waste materials.

L-Proline-Based Natural Deep Eutectic Solvents as Efficient Solvents and Catalysts for the Ultrasound-Assisted Synthesis of Aurones via Knoevenagel Condensation

Aurones are minor flavonoids that possess a wide variety of bioactivity, including antioxidant, anticancer, and enzyme inhibitory activity. L-proline-based natural deep eutectic solvents (NaDES) were synthesized and applied as solvents and catalysts for the Knoevenagel condensation reaction between benzofuranone and substituted benzaldehydes to produce aurones in high yields and purity. The reaction between benzofuranone and vanillin served as the model reaction. After screening three NaDESs, and testing microwave, as well as ultrasound as energy sources, we concluded that the optimum results are obtained using L-proline/glycerol 1:2 as catalyst and solvent and ultrasound irradiation. The scope of the reaction was evaluated using a variety of benzaldehydes, and the corresponding aurones were obtained in moderate to satisfactory yields (57–89%) and high purity. An important additional feature of the described methodology is the recyclability and reusability of the NaDES, which was recycled and effectively reused after 6 cycles.

Natural Deep Eutectic Solvents as a Key Metal Extractant for Fractionation in Speciation Analysis

The research aimed to use natural deep eutectic solvents (NADES) as an extractant for fractionation of compounds of selected elements from young barley and to compare it with the fractionation of elements from certified element materials. The use of such a comparison made it possible to prove the possibility of extracting the same forms of elements (species) from different materials, which confirmed the option of using NADES as extractants in speciation analysis. The research was conducted with hyphenated techniques—separation by high-performance chromatography coupled to an isotope-specific detector, mass spectrometry (MS) with ionization in inductively coupled plasma (ICP)—which are widely used in speciation analysis. Natural deep eutectic solvents also help introduce Green Analytical Chemistry principles (GAC). According to the results of our studies, the use of different NADES permit the extraction of various metals from a single sample. Moreover, using other natural solvents of eutectic properties helps extract different species of a given metal.

Simultaneous Hydrolysis of Ellagitannins and Extraction of Ellagic Acid from Defatted Raspberry Seeds Using Natural Deep Eutectic Solvents (NADES)

Defatted raspberry seeds were used as an alternative source of antioxidants and ellagic acid (EA) extracted using Natural deep eutectic solvents (NADES). In the preliminary study, the best NADES combination (citric acid-betaine) and the most influential variables (temperature, time, and NADES/plant ratio) were selected for the further optimization process. All samples were analyzed in terms of total polyphenol, EA content, and antioxidant activity. Two sets of optimal conditions were generated by response surface methodology. The first set (Opt1) was designed for higher conversion of ellagitannins to EA while the latter set (Opt2) for higher EA content/100 g extract. Opt1 and Opt2 had higher values for all investigated responses compared to 80% ethanolic extract but had a lower conversion rate of ellagitannins to EA compared to acidified methanol extract. The third set of parameters (Opt3) selected beyond the initial experimental domain was used to obtain a sample with the highest EA content/100 g extract. Due to their nature, NADES extracts are ready to use and could have various technological roles in products since they are antioxidants, acidifiers, and colorants. NADES raspberry extracts exhibited higher anti-proliferative activity compared to ethanolic extracts in terms of EC50 values. However, the main contributor of anti-cancer activity in NADES raspberry extracts were individual NADES compounds and/or their newly formed NADES structure.

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.

Optimization of the extraction process of flavonoids from Trollius ledebouri with natural deep eutectic solvents

In recent years, natural deep eutectic solvents have been favored greatly due to their environment friendly, mild biological toxicity and simple biodegradability. Natural deep eutectic solvents gradually applied for the extracting bioactive compounds from natural products efficiently. In this study, 20 natural deep eutectic solvents were prepared and their physical and chemical properties were tested. The ultrasonic-assisted extraction method was used to extract flavonoids from Trollius ledebouri and high-performance liquid chromatography-ultraviolet was applied to examine two main bioactive flavonoids (orientin and vitexin). Compared with traditional solvents (water and 60% ethanol solution), natural deep eutectic solvents composed of L(-)-proline and levulinic acid (molar ratio 1:2) show a super extraction efficiency. On this basis, the response surface method was used to optimize the extraction temperature, extraction time, water contents, and solid-liquid ratio. As a consequence, the extraction temperature 60℃, extraction time 18 min, water content 14% (v/v), and the solid-liquid ratio 48 mL·g^-1 were chosen as the best extraction process. This study shows that natural deep eutectic solvents can effectively extract flavonoids from T. ledebouri, laying a foundation for the further application of natural deep eutectic solvents to extract bioactive compounds from natural products.

Anticancer Activity of Natural and Synthetic Chalcones

Cancer is a condition caused by many mechanisms (genetic, immune, oxidation, and inflammatory). Anticancer therapy aims to destroy or stop the growth of cancer cells. Resistance to treatment is theleading cause of the inefficiency of current standard therapies. Targeted therapies are the most effective due to the low number of side effects and low resistance. Among the small molecule natural compounds, flavonoids are of particular interest for theidentification of new anticancer agents. Chalcones are precursors to all flavonoids and have many biological activities. The anticancer activity of chalcones is due to the ability of these compounds to act on many targets. Natural chalcones, such as licochalcones, xanthohumol (XN), panduretin (PA), and loncocarpine, have been extensively studied and modulated. Modification of the basic structure of chalcones in order to obtain compounds with superior cytotoxic properties has been performed by modulating the aromatic residues, replacing aromatic residues with heterocycles, and obtaining hybrid molecules. A huge number of chalcone derivatives with residues such as diaryl ether, sulfonamide, and amine have been obtained, their presence being favorable for anticancer activity. Modification of the amino group in the structure of aminochalconesis always favorable for antitumor activity. This is why hybrid molecules of chalcones with different nitrogen hetercycles in the molecule have been obtained. From these, azoles (imidazole, oxazoles, tetrazoles, thiazoles, 1,2,3-triazoles, and 1,2,4-triazoles) are of particular importance for the identification of new anticancer agents.

Plant Flavonoids: Chemical Characteristics and Biological Activity

In recent years, more attention has been paid to natural sources of antioxidants. Flavonoids are natural substances synthesized in several parts of plants that exhibit a high antioxidant capacity. They are a large family, presenting several classes based on their basic structure. Flavonoids have the ability to control the accumulation of reactive oxygen species (ROS) via scavenger ROS when they are formed. Therefore, these antioxidant compounds have an important role in plant stress tolerance and a high relevance in human health, mainly due to their anti-inflammatory and antimicrobial properties. In addition, flavonoids have several applications in the food industry as preservatives, pigments, and antioxidants, as well as in other industries such as cosmetics and pharmaceuticals. However, flavonoids application for industrial purposes implies extraction processes with high purity and quality. Several methodologies have been developed aimed at increasing flavonoid extraction yield and being environmentally friendly. This review presents the most abundant natural flavonoids, their structure and chemical characteristics, extraction methods, and biological activity.

Latest Insights on Novel Deep Eutectic Solvents (DES) for Sustainable Extraction of Phenolic Compounds from Natural Sources

Phenolic compounds have long been of great importance in the pharmaceutical, food, and cosmetic industries. Unfortunately, conventional extraction procedures have a high cost and are time consuming, and the solvents used can represent a safety risk for operators, consumers, and the environment. Deep eutectic solvents (DESs) are green alternatives for extraction processes, given their low or non-toxicity, biodegradability, and reusability. This review discusses the latest research (in the last two years) employing DESs for phenolic extraction, solvent components, extraction yields, extraction method characteristics, and reviewing the phenolic sources (natural products, by-products, wastes, etc.). This work also analyzes and discusses the most relevant DES-based studies for phenolic extraction from natural sources, their extraction strategies using DESs, their molecular mechanisms, and potential applications.

Ultrasonic-Assisted Extraction and Natural Deep Eutectic Solvents Combination: A Green Strategy to Improve the Recovery of Phenolic Compounds from Lavandula pedunculata subsp. lusitanica (Chaytor) Franco

The present study aimed at evaluating the effectiveness of different natural deep eutectic solvents (NADES) on the extraction of phenolic compounds from Lavandula pedunculata subsp. lusitanica (Chaytor) Franco, on the antioxidant activity, and acetylcholinesterase (AChE), butyrylcholinesterase (BChE) and tyrosinase (Tyr) inhibitory capacities. Ten different NADES were used in this research and compared with conventional solvents. Ultrasound-assisted extraction (UAE) for 60 min proved to be the best extraction condition, and proline:lactic acid (1:1) and choline chloride:urea (1:2) extracts showed the highest total phenolic contents (56.00 ± 0.77 mgGAE/gdw) and antioxidant activity [64.35 ± 1.74 mgTE/gdw and 72.13 ± 0.97 mgTE/gdw in 2.2-diphenyl-1-picrylhydrazyl (DPPH) and 2.2'-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) (ABTS) methods, respectively]. These extracts also exhibited enzymes inhibitory capacity particularly against Tyr and AChE. Even so, organic acid-based NADES showed to be the best extractants producing extracts with considerable ability to inhibit enzymes. Twenty-four phenolic compounds were identified by HPLC-HRMS, being rosmarinic acid, ferulic acid and salvianolic acid B the major compounds. The results confirmed that the combination of UAE and NADES provide an excellent alternative to organic solvents for sustainable and green extraction, and have huge potential for use in industrial applications involving the extraction of bioactive compounds from plants.

Selected Aspects Related to Medicinal and Aromatic Plants as Alternative Sources of Bioactive Compounds

Natural compounds obtained from different medicinal and aromatic plants have gained respect as alternative treatments to synthetic drugs, as well as raw materials for different applications (cosmetic, food and feed industries, environment protection, and many others). Based on a literature survey on dedicated databases, the aim of the present work is to be a critical discussion of aspects regarding classical extraction versus modern extraction techniques; possibilities to scale up (advantages and disadvantages of different extraction methods usually applied and the influence of extraction parameters); and different medicinal and aromatic plants' different applications (medical and industrial applications, as well as the potential use in nanotechnology). As nowadays, research studies are directed toward the development of modern, innovative applications of the medicinal and aromatic plants, aspects regarding future perspectives are also discussed.