A green deep eutectic solvent dispersive liquid-liquid micro-extraction (DES-DLLME) for the UHPLC-PDA determination of oxyprenylated phenylpropanoids in olive, soy, peanuts, corn, and sunflower oil

Deep eutectic solvents in analysis, delivery and chemistry of pharmaceuticals

Deep eutectic solvents (DES) have an emerging scientific role, assisting modern pharmaceutics. They are uniquely supporting the resolution of crucial issues, such as the effective extraction and isolation of bio-actives. They act as media and catalysts for pharmaceutical drug synthesis, and as green solvents and modifiers in pharmaceutical analysis. Their role in pharmaceutical formulation and drug delivery is also up-and-coming, for instance, as alternative drug-solubilizing agents, drug stabilizers and functional additives, as therapeutic deep eutectic solvents, deep eutectic API, and monomers and reaction media for the synthesis of biomaterials for advanced drug delivery. The DES also help transforming medicinal/pharmaceutical chemistry. Although DES were described in 1918, their first pharmaceutical use is only reported in 1960. In view of their broad applicability in pharmaceutics, it may be interesting to review their history, origin, evolution, potential advantages, limitations, and specific applications as green solvents. A chronological and comparative study of the literature showed the important role of DES in green approaches for modern pharmaceuticals. The concepts, applications, and outcomes of DES in pharmaceutical analysis, formulation/drug delivery, and pharmaceutical/medicinal chemistry are presented. A comprehensive outline of the atypical applications of DES as effective green solvents in pharmaceutical bioactive extraction was assessed. Efforts to present classifications of DES explored in pharmaceuticals were also made. The present manuscript also covers computational trend, adds on commercial aspects with potential future applications of DES in pharmaceutical sciences.

Handshake of deep eutectic solvent and ionic liquid: Two liquid-liquid microextraction procedures for plant analysis

Plants are subjects of interest due to the secondary metabolites in their extracts which are promising as new pharmaceuticals. Phytochemistry do not have united system of sample preparation or analysis still due to different structure of plant cells, wide broad range of chemical properties and concentrations of bioactive compounds. Such challenges can be addressed in a green chemistry manner using new approaches through smart materials in routine monitoring and researches. Liquid smart materials, such as ionic liquids (ILs) and deep eutectic solvents (DESs) are attractive due to flexible properties, lots of extraction approaches, recycle potential, and direct compatibility with powerful analytical methods. In this study DES-based microextraction procedure with pH-switching was developed. Four choline chloride DESs were suggested as selective extraction phases for polar compounds from acetonitrile extracts. Method was successfully tested on four plants (Iris sibirica L., Hypericum perforatum L., Scutellaria baicalensis G, Citrus reticulata B.). Developed procedure was optimized and validated for the choline chloride - urea (1:2 mol/mol) DES that demonstrated better results in extraction. LOD for rutin was found as 0.05 mg ml-1. For low-polar compound, imidazolium ionic liquid-based dispersive liquid-liquid microextraction procedure was developed. 1-hexyl-3-methylimidazolium salts have demonstrated desired selectivity. The main factors influencing the extraction efficiency have been identified and optimized by design of experiment on two model plants (Iris sibirica L. and Scutellaria baicalensis G.). Validation procedures were done for thymol. LOD for thymol was found as 0.021 mg ml-1. The methods were compared with each other and traditional methanol extraction. The selectivity of the smart materials supports each other, usage of such extraction phases provides same or better results as obtained with methanol.

Exploring chemical properties of essential oils from citrus peels using green solvent

The research explored the chemical characteristics of essential oils (EOs) extracted from the peels of four citrus fruits grown in northeastern Peru (lime, sweet lemon, mandarin and orange). The essential oils were extracted by hydrodistillation using a green solvent, and subsequently, their physicochemical profile, bioactive, heat capacity, and RAMAN mapping were determined; in addition, the volatile composition was determined by gas chromatography (GC-MS), and the main phenols by liquid chromatography (UHPLC). The results evidenced that sweet lemon and mandarin essential oils had higher antioxidant activity (1592.38 and 1216.13 μmol TE/g) and total phenolic content (680.78 and 420.28 mg GAE/g). In contrast, sweet lemon peel essential oil had the highest total flavonoid content (23.18 mg QE/g). D-limonene was the most abundant aromatic compound in orange (>67 %), mandarin (>70 %), and sweet lemon (>72 %) EOs; however, in the lime, it was the lowest (37 %). The most abundant component was the cyclobutane, 1,2-bis(1-methylethylethylenyl)-, trans- (32 %).

Optimizing carry-over in automated dissolution system dissoBOT for paracetamol and diclofenac sodium analysis

In this work, an automated dissolution system (dissoBOT) was used for dissolution testing for the first time. Carry-over (CO) of the dissoBOT was determined for paracetamol (PA) and diclofenac sodium (DS), which are active pharmaceutical ingredients (APIs). Initially, partial method validation of the UV-VIS spectrophotometry method for PA and DS determination was performed by defining the limit of detection (LOD), the limit of quantification (LOQ), linear concentration range, accuracy, and precision. The LODs and LOQs were less than 0.01 mg/L for both APIs. The determined linear concentration ranges were from 1.00 mg/L to 30.00 mg/L for PA and from 0.50 mg/L to 3.50 mg/L for DS (the square of the correlation coefficient was greater than 0.9990, and the quality coefficient was less than 1.00 % for both APIs). The accuracy of the method was evaluated by calculating the recovery (Re) of the solutions of standards with known concentrations. The method for both APIs was deemed to be accurate (the average Re for PA and DS were 99.81 % and 101.43 %, respectively). Precision was evaluated by calculating the relative standard deviation (RSD). The method for PA and DS was deemed to be precise, as the RSD value for PA was 0.13 %, and for DS was 0.38 %. The volume (V) of the washing medium in both cleaning cycles performed by the dissoBOT system, as well as the medium dispensing V, were established, where the medium dispensing V was in accordance with the United States Pharmacopeia requirements. The CO of the dissoBOT system, using tap water as the washing medium, was determined to be less than 1.00 % for both APIs. The CO values for one cleaning cycle of the sampling station with a V of 2 mL was in the range of 1.24-1.54 %, for V of 5 mL was in the range of 0.78-0.93 %, and for V of 10 mL was in the range of 0.27-0.36 %. In addition, the CO of the dissoBOT, when employing two cleaning cycles of the sampling station (each V of 10 mL) was reduced (CO <0.20 %). Finally, the dissoBOT was successfully employed for the dissolution PA and DS tables.

A Novel DLLME Method Involving a Solidifying Hydrophobic Deep Eutectic Solvent Using Hydrophilic Deep Eutectic Solvent as the Dispersant for the Determination of Polychlorinated Biphenyls in Water Samples

This paper presents a novel dispersive liquid-liquid microextraction (DLLME) method that employs solidified hydrophobic deep eutectic solvent (DES) with hydrophilic DES acting as the dispersant. The aim is to enrich polychlorinated biphenyls (PCBs) from water samples for subsequent determination by gas chromatography-mass spectrometry. The effects of both the hydrophobic DES as the extractant and the hydrophilic DES as the dispersant were thoroughly investigated. Optimization of the key factors influencing extraction efficiency was performed, and the method was subsequently validated. Specifically, a hydrophobic DES called DES2, prepared by combining thymol and decanoic acid in a molar ratio of 3:2, was selected as the extraction solvent. Meanwhile, a hydrophilic DES named DES6, prepared from choline chloride and acetic acid in a molar ratio of 1:2, was chosen as a dispersant. Under the optimal extraction conditions, the developed method exhibited excellent linearity over the concentration range of 0.01-5.0 µg/L, low limits of detection ranging from 3.0 to 5.1 ng/L, relative standard deviations less than 4.1%, and enrichment factors between 182 and 204 for PCBs. Finally, the effectiveness of the developed method was successfully demonstrated through residue determination of PCBs in water samples.

Deep Eutectic Solvents-Based Ultrasonic-Assisted Dispersive Liquid-Liquid Microextraction for the Determination of Organophosphorus Pesticides in Honeysuckle Dew Samples

A deep eutectic solvent (DES) with the ability to change from hydrophilic to hydrophobic was designed and synthesized and applied to the determination of organophosphorus (OPP) pesticides in honeysuckle dew samples. Choline chloride, phenol, and tetrahydrofuran (THF) were used as the hydrogen bond acceptor, hydrogen bond donor, and demulsifier, respectively. Eight OPP pesticides were extracted by DES coupled with ultrasonic-assisted extraction (UA) and then chromatographed by GC-MS. DES used as an extract solvent has the advantages of high extraction efficiency, low cost, and environmental protection. Furthermore, DES is compatible with GC-MS. The single factor experiment design and Box-Behnken design (BBD) were applied to the optimization of experimental factors, including the type and composition of extraction solvent, type of demulsifier solvent, the volume of DES and THF, pH of sample solution, and ultrasonic time. Under the optimum experimental conditions, the high degree of linearity from 0.1 to 20.0 ng mL-1 (R2 ≥ 0.9989), the limits of detection from 0.014 to 0.051 ng mL-1 (S/N = 3), and the recoveries of analytes from 81.4 to 104.4% with relative standard deviation below 8.6%. In addition, the adsorption mechanism of OPPs on DES was explored by adsorption kinetic studies. These results have demonstrated that the present method has offered an effective, accurate, and sensitive methodology for OPP pesticides in honeysuckle dew samples, and this method provides a reference for the detection of pesticide residues in traditional Chinese medicine.

Determination of chiral prothioconazole and its chiral metabolite in water, juice, tea, and vinegar using emulsive liquid-liquid microextraction combined with ultra-high performance liquid chromatography

Emulsive liquid-liquid microextraction (ELLME), a simple, rapid, and environmentally friendly technique, was established to identify chiral prothioconazole and its chiral metabolite in water, juice, tea, and vinegar using ultra-high-performance liquid chromatography (UPLC). Environmentally friendly extractant was mixed with pure water to prepare a high-concentration emulsion, which was added to samples to complete the emulsification and extraction in 1 s. Afterward, an electrolyte solution was added to complete the demulsification without centrifugation. ELLME did not use dispersants compared to the familiar dispersive liquid-liquid microextraction (DLLME), thus reducing the use of toxic solvents and avoiding the effect of dispersants on the partition coefficient. The linear range was from 0.01 to 1 mg/L. The limit of detection was 0.003 mg/L. The extraction recoveries ranged from 82.4 % to 101.6 %, with relative standard deviations of 0.7-5.2 %. The ELLME method developed has the potential to serve as an alternative to DLLME.

Development of magnetic dispersive micro-solid phase extraction of four phenolic compounds from food samples based on magnetic chitosan nanoparticles and a deep eutectic supramolecular solvent

A magnetic dispersive micro-solid phase extraction technique (CS@Fe₃O₄-MD-μSPE-DESP) based on magnetic chitosan nanoparticles and a deep eutectic supramolecular solvent was developed and applied to determinations of four phenolic compounds in food samples. To prevent environmental pollution and the introduction of toxic substances, deep eutectic supramolecular solvents (DESPs), which exhibited greater desorption capacities than conventional organic solvents and deep eutectic solvents, were used as novel green eluents for the first time. Some important parameters were screened by the Plackett-Burman method and then further optimized with response surface methodology (RSM). Under the optimal conditions, the proposed method showed excellent methodological indices with linearity over the range 0.1-200.0 µg·mL^-1, R² > 0.9988, extraction recoveries above 94.8 %, and precision (RSD%) below 2.9 %. The established method finishes the process of adsorption and desorption in approximately 3 min and enhances the efficiency for determination of phenolic compounds.

Magnetic deep eutectic solvent-based dispersive liquid-liquid microextraction for enantioselectively determining chiral mefentrifluconazole in cereal samples via ultra-high-performance liquid chromatography

A simple, rapid, and efficient pretreatment method of mefentrifluconazole enantiomers in cereal samples was established by dispersive liquid-liquid microextraction coupled with ultra-high-performance liquid chromatography-diode array detector (UHPLC-DAD). In this study, a novel ternary magnetic deep eutectic solvent (MDES) [octyltrimethylammonium bromide][cobalt chloride][acetic acid] was synthesized as the extractant. Acetic acid was used as the dispersant to promote the in situ dispersion of binary MDES [octyltrimethylammonium bromide][cobalt chloride]. The microdroplets of binary MDES containing mefentrifluconazole were separated by an external magnet. Device-assisted dispersion and time-consuming centrifugation steps were eliminated to ensure simplicity and rapidity of the pretreatment. Good linearity ranging from 0.01 μg g^-1 to 2 μg g^-1 was obtained. The extraction recovery varied from 82.9 to 95.0%. The limit of detection was 0.003 μg g^-1. Finally, this established approach has been applied for the enantioselective detection of chiral mefentrifluconazole in corn, rice, wheat, millet, and sorghum samples.

Kapok fiber-supported liquid extraction for convenient oil samples preparations: A feasibility and proof-of-concept study

In this study, a novel kapok fiber-supported liquid extraction (KF-SLE) method was developed for conveniently extracting analytes from oil samples. Natural kapok fiber without any pretreatment was directly used as an oil support medium. The extraction device was conveniently constructed by directly packing some kapok fibers into a syringe tube. Due to the fibrous property of the kapok fiber, no filter plate was needed. The cost of a KF-SLE device was as low as 0.5 CNY. The KF-SLE process was conveniently conducted using a simple three-step protocol: (1) the oil sample without any pretreatment including dilution was added directedly; (2) then, the oil-immiscible extractant was added; (3) after waiting a certain time for static extraction, the extractant was eluted out by pressing the kapok fibers with the syringe plunger. The extractant could be directly transferred for subsequent instrumental detection. For the feasibility and proof-of-concept study, the method was applied to quantify four synthetic flavor chemicals in edible oils. Satisfied quantification results were obtained with the correlation coefficient (R²) being greater than 0.996, the relative recoveries ranging from 92.90% to 107.53% and intra- and inter-day RSDs being less than 7.56%. All in all, for the first time, the SLE technique was expanded to process oil samples and the method has the characteristics of low cost, environmental friendliness, high sample processing throughput and ease of automation, offering a promising approach for edible oil sample preparations.

Deep Eutectic Liquids as Tailorable Extraction Solvents: A Review of Opportunities and Challenges

Deep Eutectic Liquids (DELs) fall among the rapidly evolving discoveries of the 21st century, and these liquids are considered as alternative solvents to toxic and volatile organic liquids. Nevertheless, the emerging trend regarding the use of DELs in every field of physical and biological sciences, a lot of ambiguities and misconceptions exist about their formation, mechanism, and efficiencies observed or projected. A review of available technical data makes it obvious that these liquids have the potential to revolutionize the underdeveloped areas of analytical chemistry particularly the extraction/enrichment of analytes. To ensure the green and sustainable use of DELs, the researchers need to have a thorough understanding of DELs, their classification, chemistry, the nature and strength of molecular entanglements, and their tailorable features. Many researchers have declared these liquids recyclable but more attentive trials are needed to develop an authentic and straightforward DELs recycling methodology. The present review covers sound background knowledge and expert opinions about the technical definition of DELs, their classification, formation, recyclability, and tailorable features for their application as extraction solvent/sorbent in analytical chemistry.

The Potential of Microextraction Techniques for the Analysis of Bioactive Compounds in Food

For a long time, the importance of sample preparation and extraction in the analytical performance of the most diverse methodologies have been neglected. Cumbersome techniques, involving high sample and solvent volumes have been gradually miniaturized from solid-phase and liquid-liquid extractions formats and microextractions approaches are becoming the standard in different fields of research. In this context, this review is devoted to the analysis of bioactive compounds in foods using different microextraction approaches reported in the literature since 2015. But microextraction also represents an opportunity to mitigate the environmental impact of organic solvents usage, as well as lab equipment. For this reason, in the recent literature, phenolics and alkaloids extraction from fruits, medicinal herbs, juices, and coffee using different miniaturized formats of solid-phase extraction and liquid-liquid microextraction are the most popular applications. However, more ambitious analytical limits are continuously being reported and emergent sorbents based on carbon nanotubes and magnetic nanoparticles will certainly contribute to this trend. Additionally, ionic liquids and deep eutectic solvents constitute already the most recent forefront of innovation, substituting organic solvents and further improving the current microextraction approaches.

Hydrophobicity-switchable deep eutectic solvent-based effervescence-assisted dispersive liquid-liquid microextraction with solidification of floating droplets for HPLC determination of anthraquinones in fried Cassiae semen tea infusions

In this paper, a hydrophobicity-switchable deep eutectic solvent was evaluated for the first time as an efficient extractant in the effervescence-assisted dispersive liquid-liquid microextraction method combined with the solidification of floating droplets for HPLC determination of anthraquinones in fried Cassiae semen tea infusions. Prepared from choline chloride and octanoic acid, the deep eutectic solvent could be switched between hydrophobic and hydrophilic forms by pH adjustment. The dispersion of the extractant was assisted by in situ CO₂ produced from the effervescence reaction between H₂SO₄ and Na₂CO₃ without using any organic solvent or auxiliary equipment. Owing to the low melting/freezing point and low density compared with water, the extractant was solidified in an ice bath for the convenience of complete separation with the sample matrix. Some important parameters, such as species, molar ratio and volume of deep eutectic solvent, species and volume of effervescent agents were optimized to achieve the best extraction efficiency. Under the optimal conditions, extraction recoveries were obtained for four anthraquinones in the range of 91.1% to 111.9%. Relative standard deviations for intraday and interday precision were less than 3.3% and 4.0%, respectively. Greenness assessment demonstrated that the proposed method was greener than other reported methods for the determination of anthraquinones.

Use of green alternative solvents in dispersive liquid-liquid microextraction: A review

Dispersive liquid-liquid microextraction is one of the most widely used microextraction techniques currently in the analytical chemistry field, mainly due to its simplicity and rapidity. The operational mode of this approach has been constantly changing since its introduction, adapting to new trends and applications. Most of these changes are related to the nature of the solvent employed for the microextraction. From the classical halogenated solvents (e.g., chloroform or dichloromethane), different alternatives have been proposed in order to obtain safer and non-pollutants microextraction applications. In this sense, low-density solvents, such as alkanols, switchable hydrophobicity solvents, and ionic liquids were the first and most popular replacements for halogenated solvents, which provided similar or better results than these classical dispersive liquid-liquid microextraction solvents. However, despite the good performances obtained with low-density solvents and ionic liquids, researchers have continued investigating in order to obtain even greener solvents for dispersive liquid-liquid microextraction. For that reason, in this review, the evolution over the last five years of the three types of solvents already mentioned and two of the most promising solvent alternatives (i.e., deep eutectic solvents and supramolecular solvents), have been studied in detail with the purpose of discussing which one provides the greenest alternative.

Oxyprenylated Secondary Metabolites as Modulators of Lipid and Sugar Metabolism

O-Prenylcoumarins (3,3-dimethylallyl, geranyl-, farnesyl- and related biosynthetic derivatives) represent a class of rarely occurring natural compounds. The most part of these secondary metabolites have been obtained from plant species belonging to the Rutaceae, Apiaceae, andFabaceae families, and from fungi, and bacteria. In the last two decades prenyloxycoumarinshave been found to possess a great potential in terms of pharmacological activities. The aim of this comprehensive review is to make a survey of the in so far reported literature citations about these valuable phytochemicals and structurally related compounds about their modulatory properties of lipid and sugar metabolism. Literature data have been acquired from the main Internet database. Several oxyprenylated secondary metabolites have been surveyed. Among these prenyloxycoumarins represented the main group exerting displayed valuable effects as modulators of lipid and sugar metabolism. The title phytochemicals have been found in common edible and fruits vegetables already known to have beneficial effects to this concern, thus enforcing the nutraceutical role of these food plants. All compounds outlined in the present review article have a great potential for the next future for the prevention and management of acute and chronic metabolic disorders.

Development of a surfactant-assisted dispersive solid phase extraction using deep eutectic solvent to extract four tetracycline antibiotics residues in milk samples

In this study, a new floating dispersive solid phase extraction method based on deep eutectic solvents has been developed in a home-made extraction device for the extraction of four tetracycline antibiotics from milk samples. In this approach, the sorbent (activated carbon) was dispersed in whole parts of solution with the aid of air stream and floated on top of the solution with the aid of the surfactant (lauryl betaine) and air bubbles. After collection of the sorbent, the adsorbed analytes were eluted with tetrabutyl ammonium chloride-propionic acid deep eutectic solvent under sonication. In this method, there was no need of organic dispersive and extraction solvents and the used sorbent was collected on top of the solution and collected without centrifugation. The validation parameters showed that low limits of detection (0.1-0.3 μg/kg) and quantification (0.6-1.0 μg/kg), acceptable enrichment factors (52-60), efficient extraction recoveries (80-91%), and satisfactory relative standard deviations (≤9.8%) were obtained. Eventually, the method was successfully applied on different milk samples and tetracycline was determined in them.

A comprehensive review on different classes of polyphenolic compounds present in edible oils

Edible oils are used as a frying medium and in the preparation of several food products. They are mainly constituting triacylglycerols as major components, while other compounds are classified as minor constituents, which include polyphenols. This class of compounds plays an important role in the thermal stability and quality attributes of the finished industrial food products. In addition to other antioxidants, the desired thermal stability of edible is achieved by either fortification or mixing of edible oils. This comprehensive review was therefore aimed to review the different classes of polyphenolic compounds present in commonly consumed edible oils. The edible oils reviewed include soybean, olive, rapeseed, canola, sunflower, flaxseed, sesame, cottonseed, palm, almond, peanut, chestnut, coconut, and hazelnut oils. The identified classes of polyphenolic compounds such as simple phenols, hydroxybenzoic acids, phenylethanoids, hydroxycinnamic acid, esters of hydroxycinnamic acids, coumarins & chromans, stilbenes, flavonoids, anthocyanins, and lignans were discussed. It was observed that a single edible from different origins showed the varied composition of the different classes of phenolic compounds. Among the oils, soybean, sunflower, olive, and brassica oils received higher attention in terms of polyphenol composition. Some classes of phenolic compounds were either not reported or absent in one edible oil, while present in others. Among the different classes of phenolics, hydroxybenzoic acids, hydroxycinnamic acid and flavonoids were the most widely present compounds. Phenolic compounds in edible oils possess several health benefits such as antioxidant, antibacterial, anti-viral, anti-inflammatory, anti-tumour, antioxidants, cardioprotective, neuroprotective, anti-diabetic properties and anti-obesity.

Phenolic compounds from virgin olive oil obtained by natural deep eutectic solvent (NADES): effect of the extraction and recovery conditions

Environmentally friendly natural deep eutectic solvents (NADES) have been shown to efficiently extract a wide range of phenolic compounds from virgin olive oil (VOO). The objective of this work was to optimize the yield of olive oil phenols extracted by NADES based on xylitol/choline choride (Xyl/ChCl). Different extraction and recovery conditions were investigated, including the effect of different extraction operating parameters (temperature, time, VOO:NADES ratio) and subsequent recovery conditions (XAD resin height, wash-water and eluent volume and pH). The highest concentration of phenols (555.36 mg/kg VOO) was obtained from extraction at 40 °C for 1 h, with a 1:1 ratio, using an adsorption resin XAD-16 with bed height of 10 cm, 250 mL acidified wash-water and 300 mL EtOH 100% as eluent. No statistically significant loss of the sum of phenolic compounds was observed when compared with the concentration values obtained by direct analysis in HPLC without the elimination of NADES. Additionally, a sequential desorption with different concentration of ethanol was used to determine the effect of the solvent concentration on polyphenol yield. Polar compounds, such as hydroxytyrosol and tyrosol, were recovered at 81.7% and 83.6%, respectively with 50 and 80% ethanol; however, 100% ethanol was required for the complete elution of oleacein (3,4-DHPEA-EDA) and oleocanthal (p-HPEA-EDA). In this paper we present an effective process for the extraction of polyphenols from VOO by NADES for direct analysis in HPLC and for the recovery and concentration of polyphenols by removing the solvent (NADES) with no losses of yield and solvent recycling.

Prenylated Trans-Cinnamic Esters and Ethers against Clinical Fusarium spp.: Repositioning of Natural Compounds in Antimicrobial Discovery

Onychomycosis is a common nail infection mainly caused by species belonging to the F. oxysporum, F. solani, and F. fujikuroi species complexes. The aim of this study was to evaluate the in vitro susceptibility of six representative strains of clinically relevant Fusarium spp. toward a set of natural-occurring hydroxycinnamic acids and their derivatives with the purpose to develop naturally occurring products in order to cope with emerging resistance phenomena. By introducing a prenylated chain at one of the hydroxy groups of trans-cinnamic acids 1–3, ten prenylated derivatives (coded 4–13) were preliminarily investigated in solid Fusarium minimal medium (FMM). Minimal inhibitory concentration (MIC) and lethal dose 50 (LD₅₀) values were then determined in liquid FMM for the most active selected antifungal p-coumaric acid 3,3′-dimethyl allyl ester 13, in comparison with the conventional fungicides terbinafine (TRB) and amphotericin B (AmB), through the quantification of the fungal growth. Significant growth inhibition was observed for prenylated derivatives 4–13, evidencing ester 13 as the most active. This compound presented MIC and LD₅₀ values (62–250 µM and 7.8–125 µM, respectively) comparable to those determined for TRB and AmB in the majority of the tested pathogenic strains. The position and size of the prenylated chain and the presence of a free phenol OH group appear crucial for the antifungal activity. This work represents the first report on the activity of prenylated cinnamic esters and ethers against clinical Fusarium spp. and opens new avenues in the development of alternative antifungal compounds based on a drug repositioning strategy.

Dispersive liquid-liquid microextraction based on a new hydrophobic deep eutectic solvent for the determination of phenolic compounds in environmental water samples

Dispersive liquid-liquid microextraction has garnered increasing attention in sample preparation due to its rapid and efficient extraction process. In this study, a new terpineol-based hydrophobic deep eutectic solvent was firstly synthesized by mixing α-terpineol with 1-octanoic acid, and then applied to analysis of phenols from water samples by dispersive liquid-liquid microextraction combined with high-performance liquid chromatography and diode array detection. Infrared spectroscopy indicated that hydrogen bonding was responsible for the formation of deep eutectic solvent between α-terpineol and 1-octanoic acid. After optimization of several parameters, such as the type and volume of deep eutectic solvent and the disperser, pH and ionic strength of sample solution, the developed method exhibited excellent extraction performance to the phenols with the enrichment factors from 27 to 32. Good linearity was acquired ranging from 5 to 5000 μg/L, and detection of limits of the proposed method for the phenols ranged from 0.15 to 0.38 μg/L. The recoveries measured by spiked samples at three concentration levels ranged from 81.6 to 99.3%, and precision was found with intra- and inter-day relative standard deviations less than 8.7 and 9.2%, respectively. Finally, the proposed method was successfully applied to the determination of the phenols in environmental water samples.

7-Isopentenyloxycoumarin: What Is New across the Last Decade

7-Isopentenyloxycoumarin is among the most widespread naturally occurring prenyloxy umbelliferone derivatives. This secondary metabolite of mixed biosynthetic origin has been typically isolated from plants belonging to several genera of the Rutaceae and Apiaceae families, comprising widely used medicinal plants and in general plants with beneficial effects on human welfare, as well as edible fruits and vegetables. Although known for quite a long time (more than 50 years), only in the last two decades has this natural compound been revealed to exert powerful and promising pharmacological properties, such as active cancer chemopreventive, antibacterial, antiprotozoal, antifungal, anti-inflammatory, neuroprotective, and antioxidant properties, among the activities best outlined in the recent literature. The aim of this comprehensive miniature review article is to detail the novel natural sources and the effects described during the last decade for 7-isopentenyloxycoumarin and what has been reported on the mechanisms of action underlying the observed biological activities of this oxyprenylated secondary metabolite. In view of the herein described data, suggestions on how to address future research on the abovementioned natural product and structurally related derivatives in the best ways according to the authors will be also provided.

Review: Microextraction Technique Based New Trends in Food Analysis

Food chemistry is the study and classification of the quality and origin of foods. The identification of definite biomarkers and the determination of residue contaminants such as toxins, pesticides, metals, human and veterinary drugs, which are a very common source of food-borne diseases. The food analysis is continuously demanding the improvement of more robust, sensitive, highly efficient, and economically beneficial analytical approaches to promise the traceability, safety, and quality of foods in the acquiescence with the consumers and legislation demands. The traditional methods have been used at the starting of the 20th century based on wet chemical methods. Now it existing the powerful analytical techniques used in food analysis and safety. This development has led to substantial enhancements in the analytical accuracy, precision, sensitivity, selectivity, thereby mounting the applied range of food applications. In the present decade, microextraction (micro-scale extraction) pays more attention due to its futures such as low consumption of solvent and sample, throughput analysis easy to operate, greener, robotics, and miniaturization, different adsorbents have been used in the microextraction process with unique nature recognized with wide range applications.

Deep eutectic solvent-based liquid-phase microextraction coupled with reversed-phase high-performance liquid chromatography for determination of α-, β-, γ-, and δ-tocopherol in edible oils

For simultaneous analysis of four fat-soluble tocopherols (α-, β-, γ-, and δ-) in edible oils, an efficient and green method using deep eutectic solvent-based liquid-phase microextraction (DES-LPME) coupled with reversed-phase high-performance liquid chromatography (RP-HPLC) was developed. The DESs formed by different quaternary ammonium salts and ethanol were used as the extractants. Tetrabutylammonium chloride (TBAC)-ethanol DES at a molar ratio of 1:2 achieved the best extraction efficiency. Under the optimized conditions, the detection limits were in the range of 2.1-3.0 ng mL^-1. The intra-day and inter-day repeatability were in the ranges of 3.9-5.3% and 4.8-7.1%, respectively, and the recoveries for the real samples varied from 80.7% to 105.4%. The developed method was successfully employed for the determination of all four tocopherol homologues with an RP-HPLC system containing a COSMOSIL π-NAP column in five edible oils collected locally. Graphical abstract.

A Review of the Use of Eutectic Solvents, Terpenes and Terpenoids in Liquid–liquid Extraction Processes

Diverse and abundant applications of the eutectic solvents have appeared in the last years. Their promising tunable properties, eco-friendly character and the possibility of being prepared from numerous compounds have led to the publication of numerous papers addressing their use in different areas. Terpenes and terpenoids have been employed in the formulation of eutectic solvents, though they also have been applied as solvents in extraction processes. For their hydrophobic nature, renewable character, low environmental impact, cost and being non-hazardous, they have also been proposed as possible substitutes of conventional solvents in the separation of organic compounds from aqueous streams, similarly to hydrophobic eutectic solvents. The present work reviews the application of eutectic solvents in liquid–liquid extraction and terpenes and terpenoids in extraction processes. It has been made a research in the current state-of-the-art in these fields, describing the proposed applications of the solvents. It has been highlighted the scale-up feasibility, solvent regeneration and reuse procedures and the comparison of the performance of eutectic solvents, terpenes and terpenoids in extraction with conventional organic solvents or ionic liquids. Ultimately, it has been also discussed the employ of predictive methods in extraction, the reliability of thermodynamic models in correlation of liquid–liquid equilibria and simulation of liquid–liquid extraction processes.

Weighted multiscale support vector regression for fast quantification of vegetable oils in edible blend oil by ultraviolet-visible spectroscopy

Weighted multiscale support vector regression combined with ultraviolet-visible (UV-Vis) spectra for quantitative analysis of edible blend oil is proposed. In the approach, UV-Vis spectra of the training set are decomposed into a certain number of intrinsic mode functions (IMFs) and a residue by empirical mode decomposition (EMD) at first. Then support vector regression (SVR) sub-models are built on each IMF and residue. For prediction set, the spectra are decomposed as done on the training set and the final predictions are obtained by integrating SVR sub-model predictions by weighted average. The weight of the sub-model is the reciprocal of the fourth power of the root mean square error of cross-validation (RMSECV). For predicting peanut oil in binary blend oil and sesame oil in ternary blend oil, the proposed method has superiority in root mean square error of prediction (RMSEP) and correlation coefficient (R) compared with SVR and partial least squares (PLS).

Green, fast and simple dispersive liquid-liquid microextraction method by using hydrophobic deep eutectic solvent for analysis of folic acid in fortified flour samples before liquid chromatography determination

A fast, simple, sensitive, and efficient vortex-assisted dispersive liquid-liquid microextraction method (VA-DES-DLME) was developed based on hydrophobic deep eutectic solvent for extraction of folic acid from flour samples followed by HPLC determination. Hydrophobic DES was prepared by mixing amylalcohol as a hydrogen bond donor and methyltriocthylammonium chloride as a hydrogen bond acceptor. Factors affecting DLLME were considered and optimized. In optimal conditions, the calibration curve was linear in the range 5.0-500 ng g^-1 with a correlation coefficient higher than 0.99. The limit of detection (LOD) and the limit of quantification (LOQ) were 1.0 and 3.0 ng g^-1, respectively. The intra-day and inter-day precision at concentrations of 10 and 100 ng g^-1 were less than 8%. Finally, application of the proposed procedure was investigated by folic acid analysis in flour samples and the relative recoveries obtained were acceptable (Recovery ≥ 90%).

Quantification of phenolic compounds in vegetable oils by mixed-mode solid-phase extraction isotope chemical labeling coupled with UHPLC-MS/MS

In the present work, a rapid, accurate and cost-effective method has been developed for the simultaneous quantification of phenolic compounds in oil using mixed-mode solid-phase extraction (SPE) coupled with chemical labeling UHPLC-MS/MS. Mix-mode SPE weak cation cartridges were selected to enrich and purify phenolic compounds in oil, and hydroxyl moiety was dansylation as stable-isotope internal standard. The major parameters that affected the extraction and chemical labeling efficiency were investigated, and the method was fully validated. The limit of quantifications and the limit of detections were 0.002 µg kg^-1 ~ 0.10 µg kg^-1 and 0.006 µg kg^-1 ~ 0.30 µg kg^-1, respectively. The recoveries were 61.2% ~ 129.3% with intra-day and inter-day precision less than 12%. The results for 38 rapeseed oils revealed that 14 phenolic compounds, including canolol, phenolic acids, phenolic alcohols, tyrosol and vanillin from trace levels to relatively high content.

Hydrophobic borneol-based natural deep eutectic solvents as a green extraction media for air-assisted liquid-liquid micro-extraction of warfarin in biological samples

In the present study, a new generation of water-immiscible natural deep eutectic solvents (DESs) was synthesized using borneol as a hydrogen-bonding acceptor and decanoic acid, oleic acid, and thymol as a hydrogen-bonding donor in different molar ratios. These green hydrophobic solvents which are chemically stable in aqueous solutions were used as extraction solvents for isolation and pre-concentration of warfarin in biological samples. In this method, fine droplets of DESs were dispersed into the sample solution by using the air-assisted liquid-liquid micro-extraction method to accelerate the cloudy emulsion system formation and increase the mass transfer of the analyte to the DES-rich phase. The borneol based deep eutectic solvent is a worthy generation of the extraction solvents in the ALLME method due to low-cost and less toxicity. A Plackett-Burman design was utilized for screening the experimental parameters. The effective parameters were then optimized by Box-Behnken design (BBD). Optimized extraction conditions were pH of sample solution of 3.9, number of aspiration/dispersion cycles of 15, the volume of DES of 60 μL, and rate and time of centrifuge of 6000 rpm and 10 min, respectively. Under the optimized conditions, the developed NADES-ALLME method exhibited a wide linear range of 5-500 µg L ^- 1 for plasma and urine samples with satisfactory recoveries above 88.80%. Limit of detections (LODs) and Limit of quantifications (LOQs) of warfarin were in the ranges of 0.5-2.7 and 1.65-8.91, respectively. The enrichment factors were obtained in the range of 148-164 and precisions were lower than 5.87%. Finally, the proposed method was successfully employed for the analysis of warfarin in human urine and plasma samples.

A novel and efficient subcritical butane extraction method and UHPLC analysis of oxyprenylated phenylpropanoids from grapefruits peels

Biologically active prenyoxyphenylpropanoids are well known to be biosynthesized by Citrus species, for which they have been found most abundantly in fruit peels. Although several extraction methodologies have been described, the development of novel and alternative extraction processes is a field of research of current interest. In this preliminary communication, we studied the performance of the subcritical butane promoted extraction of selected oxyprenylated phenylpropanoids from grapefruit peels under a counter-current mode using a handmade extraction apparatus coupled to UHPLC analysis. The application of such a method yielded 7-isopentenyloxycoumarin, auraptene, and boropinic acid in quantities higher than those recorded for other extraction methodologies like the ultrasound- and microwave-assisted macerations (0.234, 1.035, and 0.211 mg/g of dry extract respectively). The use of subcritical butane as the extraction solvent for oxyprenylated phenylpropanoids is reported herein for the first time and can be easily adopted for several other food matrices.

Dispersive liquid-liquid microextraction based on the solidification of floating organic droplets for HPLC determination of three strobilurin fungicides in cereals

In this paper, a dispersive liquid-liquid microextraction method based on the solidification of floating organic droplets, combined with high-performance liquid chromatography (DLLME-SFOD-HPLC), was developed for the detection of strobilurin fungicides (azoxystrobin, pyraclostrobin, and trifloxystrobin) in cereals. Natural fatty acids were used as an extractant and have low toxicity, density, and freezing point. The extractant nonanoic acid was evenly dispersed as droplets in sample solution and was then solidified in the upper layer of sample solution after centrifugation and ice bath, which improved the extraction and collection efficiency. The dispersive liquid-liquid microextraction procedure was optimised by univariate analysis and the Box-Behnken response surface methodology. Optimum conditions were as follows: the volume of nonanoic acid was 82 μL, the volume of acetonitrile was 620 μL, and the amount of salt was 256 mg. Under optimised conditions, the method had good linearity with a correlation coefficient higher than 0.997, and the limit of detection was 2.57-4.87 μg kg^-1. The recoveries of azoxystrobin, pyraclostrobin, and trifloxystrobin in rice, corn, and wheat were 82.0%-93.2%, and the relative standard deviations were 1.6%-7.4%. Therefore, the method was successfully applied to detect target fungicides in cereals.

Coumarins in Food and Methods of Their Determination

Coumarin is a natural product with aromatic and fragrant characteristics, widespread in the entire plant kingdom. It is found in different plant sources such as vegetables, spices, fruits, and medicinal plants including all parts of the plants-fruits, roots, stems and leaves. Coumarin is found in high concentrations in certain types of cinnamon, which is one of the most frequent sources for human exposure to this substance. However, human exposure to coumarin has not been strictly determined, since there are no systematic measurements of consumption of cinnamon-containing foods. The addition of pure coumarin to foods is not allowed, since large amounts of coumarin can be hepatotoxic. However, according to the new European aroma law, coumarin may be present in foods only naturally or as a flavoring obtained from natural raw materials (as is the case with cinnamon). In this paper, the overview of the current European regulations on coumarin levels in food is presented, along with the most common coumarin food sources, with a special emphasis on cinnamon-containing food. Human exposure to coumarins in food is also reviewed, as well as the methods for determination and separation of coumarin and its derivatives in food.

Investigation of Total Phenolic Content and Antioxidant Activities of Spruce Bark Extracts Isolated by Deep Eutectic Solvents

Extracts from spruce bark obtained using different deep eutectic solvents were screened for their total phenolic content (TPC) and antioxidant activities. Water containing choline chloride-based deep eutectic solvents (DESs) with lactic acid and 1,3-propanediol, 1,3-butanediol, 1,4-butanediol, and 1,5-pentanediol, with different molar ratios, were used as extractants. Basic characteristics of the DESs (density, viscosity, conductivity, and refractive index) were determined. All the DESs used behave as Newtonian liquids. The extractions were performed for 2 h at 60 °C under continuous stirring. TPC was determined spectrophotometrically, using the Folin-Ciocalteu reagent, and expressed as gallic acid equivalent (GAE). The antioxidant activity was determined spectrophotometrically by 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical scavenging assay. The TPC varied from 233.6 to 596.2 mg GAE/100 g dry bark; radical scavenging activity (RSA) ranged between 81.4% and 95%. This study demonstrated that deep eutectic solvents are suitable solvents for extracting phenolic compounds from spruce bark.

Synthesis and characterization of phosphocholine chloride-based three-component deep eutectic solvent: application in dispersive liquid-liquid microextraction for determination of organothiophosphate pesticides

BACKGROUND

A new type of deep eutectic solvent based on three components using phosphate salts has been synthesized, characterized, and applied in the extraction of eight organothiophosphate pesticides from honey samples. In this study, the deep eutectic solvent was prepared from phosphocholine choline chloride as a hydrogen bond acceptor and dichloroacetic acid and decanoic acid as hydrogen bond donors. The method consisted of two steps in which initially the analytes were extracted from the samples into a water-miscible organic solvent. In the second step, the extracted phase was mixed with the prepared deep eutectic solvent and the mixture was used in the following dispersive liquid-liquid microextraction method.

RESULTS

The method was validated under optimal conditions, and it was found that it has low limits of detection (0.05-0.10 ng g^-1 ) and quantification (0.19-0.36 ng g^-1 ), good linearity (r²  ≥ 0.994), broad linearity (0.36-1000 ng g^-1 ), and satisfactory repeatability (relative standard deviation ≤10% for intra- (n = 6) and inter-day (n = 4) precisions at a concentration of 2 ng g^-1 of each analyte).

CONCLUSION

The proposed method was applied in different honey samples, and malathion was found at a concentration of 29 ng g^-1 in one sample. © 2019 Society of Chemical Industry.

Deep eutectic solvents (DES) as green extraction media for antioxidants electrochemical quantification in extra-virgin olive oils

A new electroanalytical method has been developed for the determination of polar antioxidant compounds in extra virgin olive oils. This method is based on the extraction of polar antioxidant compounds from extra-virgin olive oils by means of a deep eutectic solvent and their determination by a modified screen-printed electrode platform. The platform sensitivity was increased by modifying the working electrode with MWCNT and TiO₂ nanoparticles as modifiers and Nafion as a binder. The platform showed very good sensitivity in detecting polar antioxidant compounds in extra-virgin olive oils in a fairly wide range of concentrations. The measurements were performed by using square wave voltammetry. The extraction was performed without using organic solvents, making the method environmentally friendly. The proposed method has been compared with a common spectrophotometric one, the results appeared in good agreement. The method is sufficiently easy and quick to be used for screening analyses of polar antioxidant compounds in extra-virgin olive oils on the field.