Porous phenolic resin regulated by alcohol-based deep eutectic solvent for selective extraction and separation of tanshinones from Salvia miltiorrhiza.

Deep eutectic solvents (DES), regarded as promising green solvents, have gained attention due to their distinctive properties, particularly in analytical chemistry. While the use of DES in solvent extraction and separation has been extensively studied, its application in the synthesis of adsorbents has just begun. Phenolic resin, with its polyhydroxy structure and stable spherical morphology, could serve as an effective as adsorbents for enrichment of active ingredients in herbal medicine. Designing adsorbents with high selectivity and adsorption capacity presents a critical challenge in the enrichment of active ingredients in herbal medicine. In this study, alcohol-based DESs were employed as regulators of morphology and structure instead of organic solvents, facilitating the creation of polyhydroxy structure, adjustable pores and high specific surface areas. The resulting DES-regulated porous phenolic resin demonstrated enhanced extraction and separation capacity for active ingredients compared to conventional spherical phenolic resin owing to the alcohol-based DES offering more interaction modes with the analytes.

Imidazole-modified C6 -chitosan derivatives used to extract ß-sitosterol from edible oil samples with a microwave-assisted solid phase extraction method.

ß-Sitosterol is a major bioactive constituent in plants with potent anticancer effects against many human cancer cells, but its bioavailability and therapeutic efficacy are limited by its poor solubility in water. In this study, C6 -imidazole chitosan, C6 -1-methylimidazole chitosan, C6 -1-ethylimidazole chitosan, C6 -1-vinylimidazole chitosan, C6 -1-allylimidazole chitosan, and C6 -1-butylimidazole chitosan were prepared to extract ß-sitosterol from edible oil samples via ultrasonic-assisted solid liquid extraction. The structures and properties of the newly synthesized products were characterized by Fourier transform infrared spectroscopy, scanning electron microscopy, and elemental analysis. The extraction abilities of the derivatives were tested in the experiment with high-performance liquid chromatography (limit of detection 0.21 µg/g and limit of quantification 0.67 µg/g), and the % relative standard deviation (<3.25%) and recovery values of the prepared chitosan derivatives toward ß-sitosterol (average: 100.20%) were acceptable. The spiked interday and intraday recoveries of ß-sitosterol were 102.60 ± 2.78 and 103.90 ± 3.04%, respectively. The actual amounts of ß-sitosterol extracted from three real samples using C6 -imidazole chitosan according to the solid phase extraction method were 3302.40, 901.70, and 2045.60 mg/kg for corn oil, olive oil, and pea oil, respectively.

Solid-Phase Extraction of Catechins from Green Tea with Deep Eutectic Solvent Immobilized Magnetic Molybdenum Disulfide Molecularly Imprinted Polymer.

A type of molecular-imprinted polymer with magnetic molybdenum disulfide as a base and deep eutectic solvent as a functional monomer (Fe3O4@MoS2@DES-MIP) was prepared with surface molecular imprinting method. It was applied as the adsorbent for the selective recognition and separation of (+)-catechin, (-)-epicatechin, (-)-epigallocatechin, (-)-epicatechin gallate, and (-)-epigallocatechin gallate in green tea in the process of magnetic solid-phase extraction (MSPE) combined with high-performance liquid chromatography (HPLC). The structure of Fe3O4@MoS2@DES-MIP was characterized by Fourier transform infrared spectroscopy and field emission scanning electron microscopy. The adsorption properties and selective recognition ability on (-)-epigallocatechin gallate and the other four structural analogues were examined and compared. The results show that the polymer has excellent selective recognition ability for (-)-epigallocatechin gallate, and its adsorption capacity was much higher than that of structural analogues. The Fe3O4@MoS2@DES-MIP not only has the special recognition ability to template a molecule, but also can be separated by magnets with high separation efficiency and can be used in MSPE.

Multi-phase extraction of ephedrine from Pinellia ternata and herbal medicine using molecular imprinted polymer coated ionic liquid-based silica.

INTRODUCTION: Ephedrine is a typical compound found in lots of plant species that is used in several medicines for the treatment of asthma and bronchitis. However, excess amounts are harmful to humans, so it needs to be removed. OBJECTIVE: This study developed a multi-phase extraction (MPE) method with a molecular imprinted polymer (MIP) coated ionic liquid (IL)-based silica (SiO2 @IL@MIP) to simultaneously extract and separate ephedrine from Pinellia ternata, 10 medicines, and urine samples. METHODS: IL was immobilized on silica. Subsequently, the IL was combined with the functional monomer, followed by the addition of the crosslinker and template. The resulting sorbent was applied to the MPE, and the extraction, washing and elution solvents were evaluated. RESULTS: Fourier-transform infrared (FTIR) spectroscopy and scanning electron microscopy (SEM) confirmed the synthesis of SiO2 @IL@MIP. A maximum adsorption amount of 5.76 mg/g was obtained at 30°C at a neutral pH. In MPE, 10.00 mL of methanol could extract all the ephedrine from Pinellia ternata. The interference was removed by washing with 4.00 mL of water, ethanol, and acetonitrile. Finally, 8.00 mL of methanol/acetic acid (99:1, v/v) was applied as the elution solvent. The following were extracted: 5.50 µg/g of ephedrine from Pinellia ternata, 0.00-46.50 µg/g from the 10 herbal medicines, and 68.70-102.80 µg/mL in the urine samples. CONCLUSION: The proposed method was applied successfully to the simultaneously extraction and separation of ephedrine from plants and medicines. These results are expected to provide important data for the development of new methods for the separation and purification of bioactive compounds.

Isolation of aristolochic acid I from herbal plant using molecular imprinted polymer composited ionic liquid-based zeolitic imidazolate framework-67.

Aristolochic acid I is a toxic compound found in the genus of Aristolochia plants, which are commonly used as herbal cough treatment medicines. To remove the aristolochic acid I in extract efficiently and selectively, a molecularly imprinted polymer composed of ethylimidazole ionic liquid-based zeolitic imidazolate framework-67 was synthesized and used as the adsorbent. Under the conditions optimized by the software design expert, the sorbent showed highest adsorption amount of 34.25 mg/g in methanol/water (95:5, v/v) at 39°C for 138 min. The sorbent was then applied to solid phase extraction to isolate aristolochic acid I from the extract of the herbal plant Fibraurea Recisa Pierre. 0.043 mg/g of aristolochic acid I was obtained after the loading, washing, and elution processes. The limit of detection of 2.41 × 10-5  mg/mL and good recoveries provided evidence for the accuracy of this method.

Application of Natural Deep Eutectic Solvents in the Extraction of Quercetin from Vegetables.

Quercetin is a phytochemical with disease prevention and health promotion activities that has attracted significant research attention. In this study, choline chloride and betaine-based natural deep eutectic solvents were prepared using a heating method. Their physical and chemical properties were also tested. Then, they were applied to extract quercetin from onion and broccoli with ultrasonic-assisted solid liquid method coupled with HPLC. Three factors (temperature, amount, and time) were considered for the optimization of the extraction assays. In the optimal conditions, the extraction recoveries were 88.91-98.99%, 88.45-99.01%, and 89.56-98.74% for quercetin, isorhamnetin, and kaempferol. Tailor-made natural deep eutectic solvents could be applied as sustainable and safe extraction media for biochemical applications.

Application of amino-based chitosan cyclodextrin derivatives for the extraction of catechins in green tea with high-performance liquid chromatography.

Chitosan derivatives have been studied widely, but poor solubility in water restricts their applications. In this study, four types of amine-based chitosan derivatives were prepared and modified further with beta-cyclodextrin. The sequential microextraction of catechins ((+)-catechin and (-)-epigallocatechin gallate) from green tea powder by an optimized solid-phase extraction method using these four derivatives was investigated. The optimal conditions for the extraction of catechins were 60°C for a 40 min extraction period. The purity and amount of each catechin were determined by high-performance liquid chromatography. The different amines strengthened the extraction capacity of chitosan. Among the four types of amines, ethylene diamine grafted chitosan beta-cyclodextrin had the highest extraction capacity to catechins. Therefore, this material was used in the extraction assay, and the standard curves of (+)-catechin and (-)-epigallocatechin gallate were linear over the concentration range, 0.25-500 µg/mL, after assaying five data points in duplicate. Solid-phase extraction with the amino-based chitosan beta-cyclodextrin system is a new application of chitosan, which has potential applications in the extraction of bioactive compounds from plant materials or the removal of different impurities from specific extracts.

Dual ionic liquid-immobilized silicas for multi-phase extraction of aristolochic acid from plants and herbal medicines.

A convenient, and efficient multi-phase extraction method was used to isolate aristolochic acid from real samples. To increase the efficiency, a new dual ionic liquid-immobilized silica was used as a sorbent and the effects of the adsorption conditions were investigated. IM-BIM@Sil in a methanol/water (60:40, v/v) solution at 60 °C extracted the highest amount of aristolochic acid (16.69 mg/g) compared to the other sorbents examined. The sorbent was then applied to the multi-phase extraction of aristolochic acid. After extraction eight times, 2.4-70.9 × 10-3 mg/g of aristolochic acid was isolated from nine real samples after several washing and elution steps. The recoveries of aristolochic acid ranged from 70.0% to 110.6% with relative standard deviations of 3.5%-9.1%, highlighting the accuracy of this method.

Selective extraction of 3,4-dihydroxybenzoic acid in Ilex chinensis Sims by meticulous mini-solid-phase microextraction using ternary deep eutectic solvent-based molecularly imprinted polymers.

A ternary deep eutectic solvent (TDES) was used as both template and functional monomer in the synthesis of TDES-based molecularly imprinted polymers (TDES-MIPs). A meticulous miniaturized solid-phase microextraction (mini-SPME) method followed by high-performance liquid chromatography (HPLC) were used for the optimal speciation of 3,4-dihydroxybenzoic acid (3,4-DHBA) in the needle of a syringe system with response surface methodology (RSM). Under the optimal conditions for the determination of 3,4-DHBA (amount of adsorbent (2 mg), sample volume (1 mL), cycles for adsorption and desorption (6)), the actual extraction amount was 8.46 µg g-1. The limits of detection (LODs, S/N = 3) for 3,4-DHBA in Ilex chinensis Sims were 0.26-0.31 µg mL-1, and the intra-day and inter-day precision (relative standard deviations, n = 4) after spiking with 5 µg mL-1, 100 µg mL-1, and 200 µg mL-1 were both less than 4.21%. The meticulous method (TDES-MIP-mini-SPME) combined with RSM offers a significant advance over existing methods, because of the meticulous operation and excellent selectivity of 3,4-DHBA from complex samples. Graphical abstract ᅟ.

Ternary deep eutectic solvent magnetic molecularly imprinted polymers for the dispersive magnetic solid-phase microextraction of green tea.

Ternary deep eutectic solvent magnetic molecularly imprinted polymers grafted on silica were developed for the selective recognition and separation of theophylline, theobromine, (+)-catechin hydrate, and caffeic acid from green tea through dispersive magnetic solid-phase microextraction. A new ternary deep eutectic solvent was adopted as a functional monomer. The materials obtained were characterized by FTIR spectroscopy, field emission scanning electron microscopy, transmission electron microscopy, NMR spectroscopy, and powder X-ray diffraction. The practical recovery of the theophylline, theobromine, (+)-catechin hydrate, and caffeic acid isolated with ternary deep eutectic solvent magnetic molecularly imprinted polymers in green tea were 91.82, 92.13, 89.96, and 90.73%, respectively, and the actual amounts extracted were 5.82, 4.32, 18.36, and 3.69 mg/g, respectively. The new method involving the novel material coupled with dispersive magnetic solid-phase microextraction showed outstanding recognition, selectivity and excellent magnetism, providing a new perspective for the separation of bioactive compounds.

Magnetic molecularly imprinted polymers based on silica modified by deep eutectic solvents for the rapid simultaneous magnetic-based solid-phase extraction of Salvia miltiorrhiza bunge, Glycine max (Linn.) Merr and green tea.

Novel magnetic molecularly imprinted polymers (MMIPs) with multiple-template based on silica were modified by four types of deep eutectic solvents (DESs) for the rapid simultaneous magnetic solid-phase extraction (MSPE) of tanshinone Ⅰ, tanshinone ⅡA, and cryptotanshinone from Salvia miltiorrhiza bunge; glycitein, genistein, and daidzein from Glycine max (Linn.) Merr; and epicatechin, epigallocatechin gallate, and epicatechin gallate from green tea, respectively. The synthesized materials were characterized by Fourier transform infrared spectroscopy and field emission scanning electron microscopy. Single factor experiments were to explore the relationship between the extraction efficiency and four factors (the sample solution pH, amount of DESs for modification, amount of adsorbent, and extraction time). It was showed that the DES4-MMIPs have better extraction ability than the MMIPs without DESs and the other three DESs-modified MMIPs. The best extraction recoveries with DES4-MMIP were tanshinone Ⅰ (85.57%), tanshinone ⅡA (80.58%), cryptotanshinone (92.12%), glycitein (81.65%), genistein (87.72%), daidzein (92.24%), epicatechin (86.43%), epigallocatechin gallate (80.92%), and epicatechin gallate (93.64%), respectively. The novel multiple-template MMIPs materials modified by DES for the rapid simultaneous MSPE of active compounds were proved to reduce the experimental steps than single-template technique, and increase the extraction efficiency.

Magnetic Solid-phase Extraction with Fe3O4/Molecularly Imprinted Polymers Modified by Deep Eutectic Solvents and Ionic Liquids for the Rapid Purification of Alkaloid Isomers (Theobromine and Theophylline) from Green Tea.

Different kinds of deep eutectic solvents (DES) based on choline chloride (ChCl) and ionic liquids (ILs) based on 1-methylimidazole were used to modify Fe3O4/molecularly imprinted polymers (Fe3O4/MIPs), and the resulting materials were applied for the rapid purification of alkaloid isomers (theobromine and theophylline) from green tea with magnetic solid-phase extraction (M-SPE). The M-SPE procedure was optimized using the response surface methodology (RSM) to analyze the maximum conditions. The materials were characterized by Fourier transform infrared spectroscopy (FI-IR) and field emission scanning electron microscopy (FE-SEM). Compared to the ILs-Fe3O4/MIPs, the DESs-Fe3O4/MIPs were developed for the stronger recognition and higher recoveries of the isomers (theophylline and theobromine) from green tea, particularly DES-7-Fe3O4/MIPs. With RSM, the optimal recovery condition for theobromine and theophylline in the M-SPE were observed with ratio of methanol (80%) as the washing solution, methanol/acetic acid (HAc) (8:2) as the eluent at pH 3, and an eluent volume of 4 mL. The practical recoveries of theobromine and theophylline in green tea were 92.27% and 87.51%, respectively, with a corresponding actual extraction amount of 4.87 mg•g-1 and 5.07 mg•g-1. Overall, the proposed approach with the high affinity of Fe3O4/MIPs might offer a novel method for the purification of complex isomer samples.

Exploration of a ternary deep eutectic solvent of methyltriphenylphosphonium bromide/chalcone/formic acid for the selective recognition of rutin and quercetin in Herba Artemisiae Scopariae.

Methyltriphenylphosphonium bromide/chalcone/formic acid, a green ternary deep eutectic solvent, was applied as a functional monomer and dummy template simultaneously in the synthesis of a new molecularly imprinted polymer. Ternary deep eutectic solvent based molecularly imprinted polymers are used as a solid-phase extraction sorbent in the separation and purification of rutin and quercetin from Herba Artemisiae Scopariae combined with high-performance liquid chromatography. Fourier transform infrared spectroscopy and field-emission scanning electron microscopy were applied to characterize the deep eutectic solvent based molecularly imprinted polymers synthesized using different molar ratios of chalcone. The static and competitive adsorption tests were performed to examine the recognition ability of the molecularly imprinted polymers to rutin and quercetin. The ternary deep eutectic solvent consisting of formic acid/chalcone/methyltriphenylphosphonium bromide (1:0.05:0.5) had the best molecular recognition effect. After optimization of the washing solvents (methanol/water, 1:9) and eluting solvents (acetonitrile/acetic acid, 9:1), a reliable analytical method was developed for strong recognition towards rutin and quercetin in Herba Artemisiae Scopariae with satisfactory extraction recoveries (rutin: 92.48%, quercetin: 94.23%). Overall, the chalcone ternary deep eutectic solvent-based molecularly imprinted polymer coupled with solid-phase extraction is an effective method for the selective purification of multiple bioactive compounds in complex samples.

Application of Deep Eutectic Solvents in Hybrid Molecularly Imprinted Polymers and Mesoporous Siliceous Material for Solid-Phase Extraction of Levofloxacin from Green Bean Extract.

Deep eutectic solvents (DES) are potential ecofriendly surfactants for the preparation of materials. In this study, both molecularly imprinted polymers (MIPs) and mesoporous siliceous materials (MSMs) were modified by betaine-based DES. Six materials were employed as solid phase extraction (SPE) adsorbents for the rapid purification of levofloxacin. The DES-based materials showed better selective adsorption than the conventional materials. The adsorption curves of DES-MIP showed superior molecular recognition ability and binding capability for levofloxacin compared to the other materials. The limit of detection and limit of quantitation of the method were 0.01 and 0.03 µg/mL for levofloxacin, respectively. The method recoveries at three spiked levels were 97.2 - 100.2% for DES-MIP, with an RSD <1.8%. DES-MIP showed the highest selective recovery (95.2%) for levofloxacin from the green bean extract, and could remove the interferent effectively.

Hybrid molecularly imprinted polymers modified by deep eutectic solvents and ionic liquids with three templates for the rapid simultaneous purification of rutin, scoparone, and quercetin from Herba Artemisiae Scopariae.

Different kinds of deep eutectic solvents based on choline chloride and ionic liquids based on 1-methylimidazole were used to modify hybrid molecularly imprinted polymers with the monomer γ-aminopropyltriethoxysilane-methacrylic and three templates (rutin, scoparone, and quercetin). The materials were adopted as solid-phase extraction packing agents, and were characterized by FTIR spectroscopy and field emission scanning electron microscopy. The hybrid molecularly imprinted polymers modified by deep eutectic solvents had high recoveries and a strong recognition of rutin, scoparone, and quercetin in Herba Artemisiae Scopariae than those modified by ionic liquids. In the procedure of solid-phase extraction, deep eutectic solvents-2-hybrid molecularly imprinted polymers were obtained with the best recoveries with rutin (92.27%), scoparone (87.51%), and quercetin (80.02%), and the actual extraction yields of rutin (5.6 mg/g), scoparone (2.3 mg/g), and quercetin (3.4 mg/g). Overall, the proposed approach with the high affinity of hybrid molecularly imprinted polymers might offer a novel method for the purification of complex samples.

Preparation of hybrid molecularly imprinted polymer with double-templates for rapid simultaneous purification of theophylline and chlorogenic acid in green tea.

A novel double-templates technique was adopted for solid-phase extraction packing agent, and the obtained hybrid molecularly imprinted polymers with double-templates (theophylline and chlorogenic acid) were characterized by fourier transform infrared and field emission scanning electron microscope. The molecular recognition ability and binding capability for theophylline and chlorogenic acid of polymers was evaluated by static absorption and dynamic adsorption curves. A rapid and accurate approach was established for simultaneous purification of theophylline and chlorogenic acid in green tea by coupling hybrid molecularly imprinted solid-phase extraction with high performance liquid chromatography. With optimization of SPE procedure, a reliable analytical method was developed for highly recognition towards theophylline and chlorogenic acid in green tea with satisfactory extraction recoveries (theophylline: 96.7% and chlorogenic acid: 95.8%). The limit of detection and limit of quantity of the method were 0.01 µg/mL and 0.03 µg/mL for theophylline, 0.05 µg/mL and 0.17 µg/mL for chlorogenic acid, respectively. The recoveries of proposed method at three spiked levels analysis were 98.7-100.8% and 98.3-100.2%, respectively, with the relative standard deviation less than 1.9%. Hybrid molecularly imprinted polymers with double-templates showed good performance for two kinds of targets, and the proposed approach with high affinity of hybrid molecularly imprinted polymers might offer a novel method for the purification of complex samples.

Extraction and separation of polysaccharides from Laminaria japonica by size-exclusion chromatography.

A large number of studies have suggested that polysaccharides, such as fucoidan and laminarin, in various seaweeds have significant biological properties. A different distribution of molecular weights is a prominent sign of many polysaccharides. Therefore, a simple, fast and reliable high-performance size-exclusion chromatography (HPSEC) method was proposed to separate fucoidan and laminarin from Laminaria japonica. After evaluating the different separation conditions for HPSEC, such as the type of mobile phase and flow rate, an acid extraction method was established and optimized by a systematic investigation of the influencing factors. Under the optimal conditions, 169.2 and 383.8 mg g(-1) of fucoidan and laminarin, respectively, were extracted. This method is suitable for the extraction and separation of polysaccharides with good reproducibility of the retention time, acceptable linearity, small relative standard deviation and low detection limits.

Examination of 1-methylimidazole series ionic liquids in the extraction of flavonoids from Chamaecyparis obtuse leaves using a response surface methodology.

Ionic liquids (ILs) are a new type of reagent that has accelerated research in extraction technology. On the other hand, few studies have systematically applied 1-methylimidazole ([MIM]) series ILs to the extraction of bioactive compounds from plants. In this study, [MIM] series ILs were used to extract four bioactive flavonoids, such as dihydrokaempferol, quercitrin, amentoflavone and myricetin, from Chamaecyparis obtuse (CO) leaves. First, a screen of the extraction method and solvent revealed the [MIM] series ILs to be suitable as additives in methanol in Soxhlet extraction. Second, an examination of a range of cations and anions of [MIM] series ILs for extraction revealed 1-decyl-3-methylimidazolium bromide ([DMIM][Br]) to be the best selection as an additive in methanol for the Soxhlet extraction of flavonoids from (CO) leaves. Finally, some factors of extraction, such as temperature, time and amount of samples, were examined systematically using a response surface methodology (RSM). Based on the above optimization, 2.41, 3.47, 0.76 and 3.15mg/g of dihydrokaempferol, quercitrin, amentoflavone and myricetin, respectively, were extracted from 15g of CO leaves by 2.5mgmL(-1) of [DMIM][Br] as additives in 200mL of methanol in Soxhlet extraction at 200°C for 8h. This study highlights the potential of [MIM] series ILs as promising reagents for the extraction of bioactive compounds from plants.

Evaluation of alcohol-based deep eutectic solvent in extraction and determination of flavonoids with response surface methodology optimization.

Deep eutectic solvents (DESs) are emerging rapidly as a new type of green solvent instead of an ionic liquid (IL), and are typically formed by mixing choline chloride with hydrogen bond donors. Few studies have applied DESs to the extraction and determination of bioactive compounds. Therefore, in the present study, DESs were used to extract flavonoids (myricetin and amentoflavone), which are well known and widely used antioxidants, to extend their applications. A range of alcohol-based DESs with different alcohols to choline chloride (ChCl) mixing ratios were used for extraction using several extraction methods. Other factors, such as temperature, time, water addition and solid/liquid ratio, were examined systematically using a response surface methodology (RSM). A total of 0.031 and 0.518 mg g(-1) of myricetin and amentoflavone were extracted under the optimized conditions: 35 vol% of water in ChCl/1,4-butanediol (1/5) at 70.0 °C for 40.0 min and a solid/liquid ratio of 1/1 (g 10 mL(-1)). Good linearity was obtained from 0.1 × 10(-3) to 0.1 mg mL(-1) (r(2)>0.999). The excellent properties of DESs highlight their potential as promising green solvents for the extraction and determination of a range of bioactive compounds or drugs.

Determination of organic acids in Salicornia herbacea by solid-phase extraction combined with liquid chromatography.

A solid-phase extraction (SPE) method for the determination of procatechuic acid, ferulic acid and caffeic acid in Salicornia herbacea L. (Hamcho) has been developed. The optimal conditions were obtained by using a C18 SPE cartridge. By using ethanol and acetonitrile /water/ trifluoracetic acid as washing and eluting solvents, most interfering compounds originating from the hamcho matrix were eliminated. The extracts were sufficiently clean to be directly injected into the HPLC for further chromatographic analysis. Good linearity was obtained from 0.1 to 200 microg/mL (r > 0.999) for procatechuic acid, 0.2 to 400 microg/mL (r > 0.999) for caffeic acid and 0.3 to 600 microg/mL (r > 0.999) for ferulic acid, with the relative standard deviations being less than 3.6%. The mean recoveries of procatechuic acid, ferulic acid and caffeic acid from hamcho were more than 79.2% and the detection limit (S/N = 3:1) was 0.02 microg/mL for procatechuic acid, 0.01 microg/mL for caffeic acid and 0.04 microg/mL for ferulic acid. This method is a viable alternative to the existing HPLC methods for analyzing the content of procatechuic acid, ferulic acid and caffeic acid in hamcho.