Aqueous Two-phase Extraction Research Articles

The role of the bile salt surfactant sodium deoxycholate in aqueous two-phase separation of single-wall carbon nanotubes revealed by systematic parameter variations

Aqueous two-phase (ATP) extraction has been demonstrated as a fast, scalable, and effective separation technique to sort single-wall carbon nanotubes (SWCNTs) according to their diameter and chiral structure. The exact mechanism behind the chirality-dependent migration of SWCNTs between the two phases is however not completely understood, and depends on many parameters (e.g., choice of surfactants and their concentration, pH, temperature, …), making it difficult to optimize the multivariable parameter space. In this work, we present a systematic study of the choice and concentration of specific surfactants on the ATP sorting, by performing a series of single-step ATP separations in which each time only one parameter is systematically varied, while monitoring the structure-specific migration of every SWCNT chirality between both phases with detailed wavelength-dependent spectroscopy. These systematic studies reveal that the diameter-dependent stacking of a discrete number of sodium deoxycholate molecules fitting around the SWCNT circumference determines the separation order in the form of a periodically modulated pattern as a function of SWCNT diameter. Addition of cosurfactants can be used to compete with the bile salt surfactant to enhance the separation yields, but does not affect the sorting order. The results are afterwards directly applied to predict the parameters required to separate specific chiral structures in just two ATP steps.

Study on Aqueous Two-Phase Extraction of Teapolypheols from in Green Tea

Tea polyphenols are the general name of polyphenols in tea, which are widely used in food, oil, health care, medicine, daily chemical, fine chemical and other fields. In this paper, ethanol / ammonium sulfate aqueous two-phase extraction of tea polyphenols as the main research object, by changing the single factor method, the distribution coefficient, extraction rate, yield of tea polyphenols in tea were studied. The purpose is to explore the effects of C2H5OH dosage, (NH4) 2SO4 dosage, salt dosage, extraction temperature, extraction time on the content of tea polyphenols, The results showed that the optimal distribution system was as follows: C2H5OH dosage 4.5mL, (NH4) 2SO4 dosage 2.9g, salt dosage 0.05g, water bath temperature 40°C, extraction time 20min, the extraction rate was 4.30%, and the yield was 98.80%. A new method for extracting tea polyphenols from tea was established.

A review on chemistry, therapeutic applications, extraction & purification of bromelain

This review focused on the usage of bromelain in numerous applications, as well as the most recent literature on the chemistry, extraction, and purification of bromelain from pineapple (Ananas comosus). Bromelain is a crude, aqueous extract obtained from the stems and fruits of pineapple, leading edible member of the family Bromeliaceae. Bromelain contains a mixture of different thiol endopeptidases as well as phosphatases, glucosidases, peroxidases, cellulases, & glycoproteins. It exerts its enzymatic activity over a PH range 4.5 – 9.5. The isolation & purification of bromelain has been done by various methods includes aqueous two-phase extraction, reverse micellar extraction, ultrafiltration & precipitation & chromatographic techniques. Bromelain, a cysteine protease, has found commercial use in a variety of industries including food, beverage, tenderization, cosmetic, pharmaceutical, and textile. Bromelain act as an immunomodulatory, anti-inflammatory agent, anti-oedematous, anti-thrombotic & anti-metastatic. Although the precise mechanism of action of bromelain has not been established, bromelain has received widespread acceptance as a phytotherapeutic agent due to its long history of safety and absence of adverse effects

Ultrasound assisted aqueous two-phase extraction of polysaccharides from Cornus officinalis fruit: Modeling, optimization, purification, and characterization

Ultrasound assisted aqueous two-phase extraction of polysaccharides from Cornus officinalis fruit was modeled by response surface methodology (RSM) and artificial neural network (ANN), and optimized using genetic algorithm coupled with ANN (GA-ANN). Statistical analysis showed that the models obtained by RSM and ANN could accurately predict the Cornus officinalis polysaccharides (COPs) yield. However, ANN prediction was more accurate than RSM. The optimum extraction parameters to achieve the highest COPs yield (7.85 ± 0.09)% was obtained at the ultrasound power of 350 W, extraction temperature of 51 ℃, liquid-to-solid ratio of 17 mL/g, and extraction time of 38 min. Subsequently, the crude COPs were further purified via DEAE-52 and Sephadex G-100 chromatography to obtain a homogenous fraction (COPs-4-SG, 33.64 kDa) that contained galacturonic acid, arabinose, mannose, glucose, and galactose in a molar ratio of 34.82:14.19:6.75:13.48:12.26. The structure of COPs-4-SG was also characterized with UV–vis, fourier-transform infrared spectroscopy (FT–IR), atomic force microscopy (AFM), scanning electron microscopy (SEM), Congo-red test, and circular dichroism (CD). The findings provide a feasible way for the extraction, purification, and optimization of polysaccharides from plant resources

Aqueous Two-Phase Extraction, Antioxidant and Renal Protective Effects of Polysaccharides from Spores of Cordyceps cicadae

The aim of this study was to investigate the aqueous two-phase extraction (ATPE), in vitro antioxidant, and in vivo renal protective effects of polysaccharides from spores of Cordyceps cicadae (CCSPs). The optimal ATPE parameters were as follows: an extraction temperature of 61 °C, an ammonium sulfate concentration of 18%, an ethanol concentration of 40%, a liquid-to-material ratio of 33 mL/g, and an extraction time of 60 min. Under these parameters, the CCSPs yield was 6.96 ± 0.11% (n = 3), which was consistent with the predicted yield (6.92%). Among the three purified polysaccharide fractions, CCSP-2 displayed stronger scavenging activities against DPPH radicals and hydroxyl radicals, reducing power and ferrous-ion-chelating ability to a greater extent than CCSP-1 and CCSP-3. CCSP-2 exhibited its protective effect in lipopolysaccharide (LPS)-induced septic acute kidney injury (AKI) mice by significantly alleviating renal edema; reducing 24 h urine protein, blood urea nitrogen (BUN), and serum creatinine (SCr); inhibiting the release of serum proinflammatory cytokines; boosting the activities of antioxidant enzymes; and reducing the levels of oxidative damage products. These results suggest that CCSP-2 exerted its protective effect against LPS-induced septic AKI in mice through anti-inflammatory and antioxidant pathways.

A correlative algorithmic optimization study for an integrated soft computing technique in aqueous two-phase protein extraction from Litopenaeus vannamei waste

A correlative algorithmic optimization study for an integrated soft computing technique in aqueous two-phase protein extraction from Litopenaeus vannamei waste

Ultrasound-assisted aqueous two-phase extraction of total flavonoids from Tremella fuciformis and antioxidant activity of extracted flavonoids

Here, the extraction of total flavonoids from Tremella fuciformis (TF) by aqueous two-phase extraction combined with ultrasound is presented. The extraction was optimized via a single-variable approach using the variables of mass fraction of ethanol and NaH2PO4, ultrasonication time, and TF sample amount. Response surface methodology (RSM) was then applied to determine the best conditions for extraction using the following three key parameters: ultrasonication time, ethanol mass fraction, and NaH2PO4 mass fraction. The optimum conditions were as follows: an aqueous two-phase system of ethanol/NaH2PO4, an ethanol mass fraction of 23%, a NaH2PO4 mass fraction of 27.18%, and an extraction time of 8.25 min. Under these conditions, the maximum extraction rate of total flavonoids was 0.158 mg/g. The scavenging rates for superoxide anion and hydroxyl radical, as well as the antioxidant activity of total flavonoids in TF, were studied. Total flavonoids from TF showed some scavenging ability, but the scavenging effects were lower than those of vitamin C (Vc) at the same concentrations. Nevertheless, ultrasound-assisted two-phase extraction was considered an efficient and rapid method that can be used to extract total flavonoids from TF.

Effect of Microwave-Assisted Aqueous Two-Phase Extraction of α-Solanine from S. retroflexum and Analysis on UHPLC-qTOF-MS

Abstract A new, fast and efficient method, hyphenated microwave-assisted aqueous two-phase extraction (MA-ATPE) was applied in the extraction of α-solanine from Solanum retroflexum. This environmentally friendly extraction method applied water and ethanol as extraction solvents. Central composite design (CCD) was performed which included numerical parameters such as time, mass of plant powder and microwave power. The categorical factors included the chaotrope — NaCl or the kosmotrope — Na2CO3. Fitting the central composite design response surface model to the data generated a quadratic model with a good fit (R2 = 0.920). The statistically significant (p < 0.05) parameters such as time and mass of plant powder were influential in the extraction of α-solanine. Quantification of α-solanine was achieved using a robust and sensitive feature of the ultra-high performance quadrupole time of flight mass spectrometer (UHPLC-qTOF-MS), multiple reaction monitoring (MRM). The optimized condition for the extraction of α-solanine in the presence of NaCl and Na2CO3 was a period of 1 min at a mass of 1.2 g using a microwave power of 40%. Maximal extraction of α-solanine was 93.50 mg kg−1 and 72.16 mg kg−1 for Na2CO3 and NaCl, respectively. The synergistic effect of salting-out and microwave extraction was influential in extraction of α-solanine. Furthermore, the higher negative charge density of the kosmotrope (Na2CO3) was responsible for its greater extraction of α-solanine than chaotrope (NaCl). The shorter optimal extraction times of MA-ATPE make it a potential technique that could meet market demand as it is a quick, green and efficient method for removal of toxic metabolites in nutraceuticals.

Variations in bile salt surfactant structure allow tuning of the sorting of single-wall carbon nanotubes by aqueous two-phase extraction.

Being some of the most efficient agents to individually solubilize single-wall carbon nanotubes (SWCNTs), bile salt surfactants (BSS) represent the foundation for the surfactant-based structure sorting and spectroscopic characterization of SWCNTs. In this work, we investigate three BSS in their ability to separate different SWCNT chiral structures by aqueous two-phase extraction (ATPE): sodium deoxycholate (DOC), sodium cholate (SC) and sodium chenodeoxycholate (CDOC). The small difference in their chemical structure (just one hydroxyl group) leads to significant differences in their stacking behavior on SWCNT walls with different diameter and chiral structure that, in turn, has direct consequences for the chiral sorting of SWCNTs using these BSS. By performing several series of systematic ATPE experiments, we reveal that, in general, the stacking of DOC and CDOC is more enantioselective than the stacking of SC on the SWCNT walls, while SC has a clear diameter preference for efficiently solubilizing the SWCNTs in comparison to DOC and CDOC. Moreover, combining sodium dodecylsulfate with SC allows for resolving the ATPE sorting transitions of empty and water-filled SWCNTs for a number of SWCNT chiralities. We also show that addition of SC to combinations of DOC and sodium dodecylbenzenesulfonate can enhance separations of particular chiralities.

Enrichment of high-purity large-diameter semiconducting single-walled carbon nanotubes.

Semiconducting single-walled carbon nanotubes SWCNTs (s-SWCNTs) are considered one of the most promising alternatives to traditional silicon-based semiconductors. In particular, large-diameter s-SWCNTs (>1.2 nm) exhibit more advantages over small-diameter ones in high-performance electronic applications because of their higher charge carrier mobility and reduced Schottky barrier height. Great efforts have been made to enriching large-diameter s-SWCNTs from mass-produced raw CNTs that contain both metallic SWCNTs and s-SWCNTs. Among separation technologies, the effective and scalable ones are conjugated polymer wrapping (CPW), gel permeation chromatography (GC), aqueous two-phase extraction (ATPE), and density gradient ultracentrifugation (DGU). In this review, we survey recent progress on enriching large-diameter s-SWCNTs using those methods and outline the strategies and challenges in the separation according to the electronic type and chirality of SWCNTs. Finally, we highlight some applications of the enriched large-diameter s-SWCNTs and outlook for the future of SWCNT-based electronic devices.

A novel electrochemical sensing platform based on the esterase extracted from kidney bean for high-sensitivity determination of organophosphorus pesticides.

Similar to acetylcholinesterase, the activity of plant-derived esterase can also be inhibited by organophosphorus pesticides. Therefore, an electrochemical sensing platform using kidney bean esterase as a new detection enzyme was proposed for the highly sensitive determination of organophosphorus pesticides. Purified kidney bean esterase was obtained by an efficient and economical aqueous two-phase extraction method. Carboxylated graphene/carbon nanotube composites (cCNTs–cGR) and Au nanoparticles were used to provide a biocompatible environment to immobilize kidney bean esterase and also accelerate electron transport between the analyte and the electrode surface. Due to the good synergistic electrocatalytic effects of these nanomaterials, the biosensor exhibited an amplified electrocatalytic response to the oxidation of α-naphthalenol, which makes the sensor more sensitive. Based on the inhibitory effect of trichlorfon on kidney bean esterase activity, high sensitivity and low-cost detection of trichlorfon was achieved. Under optimum conditions, the inhibition of trichlorfon is proportional to its concentration in the range of 5 to 150 ng L−1 and 150 ng L−1 to 700 ng L−1 with an ultra-low detection limit of 3 ng L−1. Moreover, the validity of the prepared biosensor was verified by analyzing several actual agricultural products (cabbage and rice) with satisfactory recoveries ranging from 94.05% to 106.76%, indicating that kidney bean esterase is a promising enzyme source for the analysis of organophosphorus pesticides in food samples.

The effect of ultrasonic extraction methods on extract quality from Strobilanthes crispus L.

Strobilanthes crispus L. leaves are known to have many health benefits that have been proven both traditionally and in scientific research. To achieve more benefits from the leaves of Strobilanthes crispus L., the ultrasonic extraction (53 kHz) method was carried out using various ways. The variations of the ultrasonic method being carried out are UAE (Ultrasound-Assisted Extraction), UAEE (Ultrasound-Assisted Enzymatic Extraction), UAE-ATPE (Ultrasound-Assisted Enzymatic Aqueous Two-Phase Extraction) sequence and simultaneously. Extraction was carried out at 27 °C for 1hour, enzymatic hydrolysis reaction for 2 hours with a cellulose concentration of 7% w/w dry leaves, and the ATP (Aqueous Two-Phase) system of ethanol-ammonium sulfate of 33-14% w/w. The extract parameters measured were the yield, TPC (Total Phenolic Content), and TFC (Total Flavonoid Content) values. The highest yield was obtained by the Hydrolysis/UAE-ATPE method simultaneously, namely 80.94% w/w dry biomass. The highest TPC and TFC values were obtained from the extraction using the Hydrolysis/UAE-ATPS method simultaneously, i.e. 5.517 and 3.332 mg/g dry biomass respectively. Thus, it can be concluded that the simultaneous use of hydrolysis enzymatic with the cellulase enzyme and the ATP system in the ultrasonic extraction method can increase the quantity and quality of Strobilanthes crispus L. leaves extract.

Microwave-assisted polyethylene glycol-based aqueous two-phase extraction of gallic acid and ellagic acid from Euonymus alatus: Process optimization, quantification analysis and antioxidant activity

A novel method of extraction and separation of gallic acid and ellagic acid from Euonymus alatus was developed by microwave-assisted extraction (MAE) coupled with aqueous surfactant two-phase extraction (ASTPE). Using PEG-400/(NH4)2SO4 system as the extractant, the effects of key factors on the extraction yields of the phenolic acids were investigated by response surface methodology. The optimized extraction conditions were as follows: (NH4)2SO4 concentration 17.74% (w/w), PEG-400 concentration 25.94% (w/w), extraction temperature 95.40 °C and liquid-to-material ratio of 59.99:1. The results of validation experiments were close to the predictedvalues of the model. The extraction yields of the phenolic acids for MAE-ASTPE were superior to that of conventional methods. The proposed approach coupled to high-performance liquid chromatography was successfully applied for extraction and determination of the phenolic acids in three batches of Euonymus alatus. The extraction yields of gallic acid and ellagic acid were 0.4532 ± 0.0031, 0.5864 ± 0.0061, 0.4966 ± 0.0056 mg/g and 0.1713 ± 0.0043, 0.3072 ± 0.0030, 0.1374 ± 0.0015 mg/g, respectively. The extract obtained by MAE-ASTPE had stronger antioxidant activity, and EC50 values of scavenging DPPH (2,2-diphenyl-1-picrylhydrazyl), hydroxyl, superoxide and ABTS (2,2′-azinobis-3-ethylbenzothiazoline-6-sulfonic acid) radicals were respectively 198.5 ± 1.2, 358.0 ± 2.8, 776.3 ± 3.3 and 333.6 ± 1.8 μg/mL. MAE integrated with ASTPE could improve not only extraction efficiency but also extraction selectivity, and facilitated to develop natural antioxidant from Euonymus alatus.

Hyphenation of aqueous two-phase and microwave extraction of solasonine and solamargine from leaves of Solanum mauritianum characterized by UHPLC-qTOF-MS

The biomass Solanum mauritianum (S. mauritianum) is an invasive weed specie; however, it is a source of medicinally important metabolites, as reported in literature, such as solasonine and solamargine. The study was directed at the optimization of microwave and aqueous two-phase-based extraction techniques which involved microwave-assisted extraction (MAE), aqueous two-phase extraction followed by microwave-assisted extraction (ATPE + MAE), and the “one-pot” microwave-assisted aqueous two-phase extraction (MA-ATPE) for extraction of solasonine and solamargine from leaves of S. mauritianum which was evaluated. The microwave-assisted extraction of solasonine and solamargine yielded optimums at 5.00 min, microwave power of 270 W, and solid/liquid of 0.1 g L−1 at an ethanol concentration of 60%. Application of a two-stage extraction (MAE + ATPE) in CaO-dried alcohol resulted in decreased amounts of solasonine and solamargine extracted. The best yields of solasonine and solamargine were achieved in the MA-ATPE method. Extraction of solamargine and solasonine using Na2CO3 in CaO-dried ethanol during MA-ATPE was approximately threefold and twofold greater than that of MAE + ATPE, respectively. Furthermore, extraction of solamargine and solasonine using NaCl in CaO-dried ethanol during MA-ATPE was approximately twofold greater than that of MAE + ATPE. The synergy of microwaves and salting-out in the “one-pot” MA-ATPE technique was shown to be a contributing factor for enhanced extraction of solamargine and solasonine from leaves of S. mauritianum. Application of this time- and energy-efficient extraction method could potentially be expanded for enrichment of medicinally important compounds from biomass of other medicinal plants.

Remediation of diesel-contaminated soil by alkoxyethanol aqueous two-phase system.

The increasing diesel pollution accidents pose a serious threat to the ecological environment and human health. Remediation of diesel-contaminated soil (DCS) has attracted widespread attention during the past few decades. This work proposed an approach for the remediation of DCS by alkoxyethanol aqueous two-phase extraction (ATPE), which was an application of this small molecule aqueous two-phase system (ATPS). In addition, the influence of temperature, stirring speed, stirring time, and solid-liquid ratio on the removal of diesel was explored respectively. The removal efficiency of diesel could reach more than 97.18% in 18min. Meanwhile, ATPS had high reusability, and the removal efficiency remained above 85.17% in the reuse process. Alkoxyethanol ATPE could effectively remove diesel hydrocarbons with different carbon chain lengths and the remediation process hardly caused residual organic solvents on the soil surface according to the analysis of gas chromatography-mass spectrometry (GC-MS) and Fourier transforms infrared (FT-IR), which could be regarded as the distinct advantage compared to the traditional surfactant washing method and organic solvent extraction method. The study of soil physicochemical properties and wheat germination proved that the soil structure and properties changed little after ATPE remediation. And finally, the mechanism of alkoxyethanol ATPE was intensively discussed according to the remediation characteristic. This work provided an efficient method for the remediation of DCS and widened the application fields of alkoxyethanol ATPS as well.

Probing Liquid-Liquid Phase Separation in Secondary Organic Aerosol Mimicking Solutions Using Articulated Straws.

The presence or absence of liquid–liquid phase separation (LLPS) in aerosol particles containing oxidized organic species and inorganic salts affects particle morphology and influences uptake into, diffusion through, and reactivity within those particles. We report here an accessible method, similar to ice core analyses, using solutions that are relevant for both aerosol chemical systems and aqueous two-phase extraction systems and contain ammonium sulfate and one of eight alcohols (methanol, ethanol, 1-propanol, 2-propanol, 2-butaonol, 3-methyl-2-butanol, 1,2-propanediol, or 1,3-propanediol) frozen in articulated (bendable) straws to probe LLPS. For alcohols with negative octanol–water partitioning coefficient (KOW) values and O/C ratios ≥0.5, no LLPS occurs, while for alcohols with positive KOW values and O/C ratios ≤0.33, phase separation always occurs, both findings consistent with observations using different experimental techniques. When a third species, glyoxal, is added, the glyoxal stays in the aqueous phase, regardless of whether LLPS occurs. When phase separation occurs, the glyoxal forms a strong intermolecular interaction with the sulfate ion, red-shifting the ν3(SO42–) peak by 15 cm–1. These results provide evidence of chemical interactions within phase-separated systems that have implications for understanding chemical reactivity within those, and related, systems.

Aqueous two-phase extraction of single-walled carbon nanotubes using nonionic surfactant Tween 60

<p indent="0mm">Due to its excellent electronic and optical properties, single-walled carbon nanotubes (SWNTs) have attracted extensive attention. Since the property of SWNTs is determined by their structures, applications like high-performance devices require SWNTs with identical structures and uniform properties. Therefore, the sorting of SWNTs is of great significance. Aqueous two-phase (ATP) extraction is an emerging method that can be utilized to realize the structure sorting of SWNTs. ATP extraction is a repeatable and reliable technique that does not require state-of-the-art equipment. It is efficient and easy to scale up. In this article, by adjusting the concentration of sodium deoxycholate (DOC) and nonionic surfactant Tween 60, the diameter sorting of SWNTs and the separation of high purity (6,5) tubes were achieved. The sorting can be carried out at a higher DOC concentration, which could improve the competitive coating between DOC and Tween 60 on the surface of SWNTs, and further improve the sorting efficiency of the co-surfactant system. The comparison of the separation results between the Tween 60-DOC surfactant system and the SDS-DOC surfactant system shows that the introduction of nonionic surfactant Tween 60 is beneficial to the separation of higher purity (6,5) tubes.

Optimization of an ultrasonic-assisted aqueous two-phase extraction method for four flavonoids from Lysionotus pauciflorus

An effective approach to extracting four flavonoids (lysioside C, nevadensin-7-sambubioside, ikarisoside B, and nevadensin) from Lysionotus pauciflorus using ultrasonic-assisted aqueous two-phase extraction (UAATPE) technology was studied. Ethanol/K2HPO4 system was selected and the influence of several important parameters, including composition of the aqueous two-phase system (ATPS), extraction temperature and time, particle size, and solvent to material ratio, were investigated by single factor experimentss. Then three key parameters (ethanol concentration, solvent to material ratio and extraction temperature) were further optimized by response surface methodology (RSM). The optimal process was that 1 g 120 mesh herb powders were extracted with 45 g ATPS (made of 30% ethanol/18% K2HPO4) in 43 °C for 30 min, and yields of four flavonoids could reach 2.56, 2.06, 3.62, and 6.28 mg/g, respectively. Compared with ultrasonic-assisted extraction (UAE) in three conventional solvents (water, ethanol and 60% ethanol), the UAATPE displayed comparatively higher extraction capability. Therefore, UAATPE in ethanol/K2HPO4 system could be an alternative technology for integrated extraction of the flavonoids from L. pauciflorus.

Subcritical Ethanol-Water and ionic liquid extraction systems coupled with multi-frequency ultrasound in the extraction and purification of polysaccharides

ABSTRACT This study obtained crude sorghum leaf sheath polysaccharide (39.99% wet matter (wm)) by subcritical ethanol-water (40% v/v) extraction (180°C, 40 min). The subcritical extraction solution was transformed into an ionic liquid aqueous two-phase extraction system and subsequently coupled with ultrasound extraction to obtain partially purified polysaccharides (PPP). PPP yields of 20.89%, 27.38%, and 36.49% (wm) were obtained using 60 kHz, 20/60 kHz, and 20/40/60 kHz ultrasound frequencies, respectively. Polysaccharide functional groups such as hydroxyl, aldehyde, and amide were detected using Fourier Transform Infrared Spectroscopy (FT-IR). Amylose contents of 15%, 18%, and 25% were obtained for PPP under single, dual, and tri-frequencies, respectively. Amylose contents were associated with aggregation of PPP particles sizes after heat exposure (70°C for 1 h 50 min). Triple-frequency extracted polysaccharides with the highest uronic acid (1.51%) and polyphenolic (27.79%) contents had an IC50 of 1.37 mg/mL in an in-vitro hydroxyl scavenging activity assay. Three interesting co-extracted bioactive phytochemicals; 2-amino-5[(2-carboxy)vinyl]-Imidazole, N-[4-bromo-n butyl]-2-Piperidinone, and 3-Trifluoroacetyl Pentadecane were detected. The PPP extract showed antioxidant activity and contained phytochemicals with potential antimicrobial and antiviral activities, and thus may be useful in food, nutraceutical, and pharmaceutical applications.

Ultrasonic-Assisted Aqueous Two-Phase Extraction Combined with Macroporous Resin Enrichment of Lignans from Flaxseed Meal and Their Antioxidant Activities.

Secoisolariciresinol diglucoside (SDG) is a natural antioxidant generally extracted from flaxseed, which is one of the most important oil crops in China, the by-product of the flaxseed oil, i.e., flaxseed meal still contains a lot of lignans. However, flaxseed meal is generally treated as waste, resulting in a huge waste of resources. To establish an efficient and convenient method for extraction and purification of lignans from flaxseed meal. First, we used response surface methodology (RSM) to optimize the extraction conditions of the ultrasonic-assisted (UA) aqueous two-phase system (ATPS), and we obtained the purified extracts by macroporous resin purification (MRP). Second, the antioxidant ability of the extracts was studied in vitro. The best extraction conditions obtained were as follows: 9.0% (w/w) sodium hydroxide; 30.0% (w/w) isopropanol; extraction time, 39 min; liquid-to-solid ratio, 52.0 mL/g; ultrasonic wave, 560 W; and extraction temperature, 40°C. Under the optimal conditions, the purity of crude extracts (SDG-APTS-C) reached 21.5%. The desorption conditions of MRP were as follows: eluting 3 BV with ultrapure water, and then eluting with 25% ethanol at 2 BV (bed volume)/h to collect eluents. The purified extracts (SDG-ATPS-P) had a purity quotient of 73.9%, which was 52.4% higher than that of SDG-ATPS-C. Additionally, experiments conducted revealed that SDG-ATPS-C and SDG-ATPS-P could effectively remove DPPH (2,2-Diphenyl-1-picrylhydrazyl), ABTS （2,-Azinobis-3-ethylbenzthiazoline-6-sulphonate）, and hydroxyl free radicals in vitro. The method was validated for extracting SDG from flaxseed meal, thus achieving the reuse of flaxseed meal. This research provides some references for the application of UAATPS combined with MRP in natural products.