Extraction, Preconcentration and Isolation of Flavonoids from Apocynum venetum L. Leaves Using Ionic Liquid-Based Ultrasonic-Assisted Extraction Coupled with an Aqueous Biphasic System

Economical one-pot synthesis of isoquercetin and D-allulose from quercetin and sucrose using whole-cell biocatalyst

Isoquercetin and D-allulose have diverse applications and significant value in antioxidant, antibacterial, antiviral, and lipid metabolism. Isoquercetin can be synthesized from quercetin, while D-allulose is converted from D-fructose. However, their production scale and overall quality are relatively low, leading to high production costs. In this study, we have devised a cost-effective one-pot method for biosynthesizing isoquercetin and D-allulose using a whole-cell biocatalyst derived from quercetin and sucrose. To achieve this, the optimized isoquercetin synthase and D-allulose-3-epimerase were initially identified through isofunctional gene screening. In order to reduce the cost of uridine diphosphate glucose (UDPG) during isoquercetin synthesis and ensure a continuous supply of UDPG, sucrose synthase is introduced to enable the self-circulation of UDPG. At the same time, the inclusion of sucrose permease was utilized to successfully facilitate the catalytic production of D-allulose in whole cells. Finally, the recombinant strain BL21/UGT-SUS+DAE-SUP, which overexpresses MiF3GTMUT, GmSUS, EcSUP, and DAEase, was obtained. This strain co-produced 41±2.4 mg/L of isoquercetin and 5.7±0.8 g/L of D-allulose using 120 mg/L of quercetin and 20 g/L of sucrose as substrates for 5 h after optimization. This is the first green synthesis method that can simultaneously produce flavonoid compounds and rare sugars. These findings provide valuable insights and potential for future industrial production, as well as practical applications in factories.

Advances of Imidazolium Ionic Liquids for the Extraction of Phytochemicals from Plants

In this review, we present the research from 2013 to 2022 about the character of ionic liquids, the categories of phytochemicals, and the reasons for selecting imidazolium ionic liquids for phytochemical extraction. Then we introduce the structural formulae of the imidazolium ionic liquids commonly used in the extraction of phytochemicals, the methods used to prepare imidazolium ionic liquids, and a comprehensive introduction of how imidazolium ionic liquids are applied to extract phytochemicals from plants. Importantly, we discuss the strategies for studying the extraction mechanisms of imidazolium ionic liquids to extract phytochemicals, and the recovery methods regarding imidazolium ionic liquids and their recyclability are analyzed. Then the toxicity in imidazolium ionic liquids is pointed out. Finally, the challenges and prospects of extracting phytochemicals by imidazolium ionic liquids are summarized, and they are expected to provide some references for researchers.

Simultaneous Extraction and Determination of Characteristic Steroidal Saponins and Homoisoflavonoids in Zhejiang Ophiopogon japonicus

Zhejiang Ophiopogonjaponicus (ZOJ) is a specific variety of Ophiopogon japonicus with characteristic steroidal saponins and homoisoflavonoids, which are also main pharmacodynamic constituents with clinical effects, including curing inflammation and cardiovascular diseases. However, few analysis methods were applied to simultaneously and quantitatively determine two kinds of its constituents, and hazardous organic solvents are mostly used for extraction. In this study, a new validated simultaneous extraction and determination method for four characteristic steroidal saponins and homoisoflavonoids in ZOJ was established by ionic liquid–ultrasonic extraction (IL-UAE) combined with HPLC-DAD-ELSD analysis, which can be used for the quality control of ZOJ. Chromatographic separation was performed with a DAD wavelength at 296 nm, and the ELSD parameters of the drift tube temperature (DTT), atomizer temperature (AT), and nitrogen gas pressure (NGP) were set at 20% heating power, 70 °C, and 25 psi, respectively. The optimal IL-UAE conditions were 1 mol/L [Bmim]CF₃SO₃ aqueous solution, a liquid–material ratio of 40 mL/g, and an ultrasonic time of 60 min. The proposed method is reliable, reproducible, and accurate, which were verified with real sample assays. Consequently, this work will be helpful for the quality control of ZOJ. It can also present a promising reference for the simultaneous extraction and determination of different kinds of constituents in other medicinal plants.

Structural characterization and immunoregulatory activity of a neutral polysaccharide from the roots of Apocynum venetum L

The structural characteristics and immunoregulatory activities of neutral heteropolysaccharide (AVRP-N) separated from the roots of Apocynum venetum L. were extensively investigated. The results showed that the weight average molecular mass (Mw) of AVRP-N was 6.430 × 10³ Da. Moreover, the backbone is composed of natural acetylated (1 → 4)-β-D-Man and (1 → 5)-α-L-Ara domains. The mannan is composed of →4)-β-D-Manp-(1→, →4)-β-D-Glcp-(1→, and the terminal group α-D-Galp-(1→ attached to →4,6)-β-D-Manp-(1→ at O-6. Araban is composed of →5)-α-L-Araf-(1→; the terminal group α-L-Araf-(1→attached to→2,3,5)-α-L-Araf-(1→ at O-2, O-3 and →3,5)-α-L-Araf-(1→ at O-3. In addition, the senior structure shows that AVRP-N has a triple-helix conformation. Furthermore, AVRP-N exhibited immunomodulatory effects, which could significantly regulate the proliferation of mouse splenic lymphocytes by enhancing the secretion of the cytokines (IFN-γ, IL-2, IL-4, and IL-10). Our results provide new structural and immunoregulatory information for natural polysaccharides derived from Apocynum venetum L.

Purified Saponins in Momordica charantia Treated with High Hydrostatic Pressure and Ionic Liquid-Based Aqueous Biphasic Systems

Momordica charantia L. (Cucurbitaceae) is rich in saponins, which have multiple biological effects. In this study, the total saponins of M. charantia were extracted by high hydrostatic pressure (HHP) technology. The optimal extraction process was determined (ethanol concentration 68%, pressure-holding time 8 min, ratio of material to solvent 1:35 and pressure 510 MPa), and the extraction amount of saponins reached 127.890 mg/g. On this basis, an ionic liquid-based aqueous biphasic system was constructed to purify the total saponins. Under the optimized conditions, the purity of M. charantia saponins was 76.06%. Liquid chromatography–mass spectrometry (LC/MS) was used to characterize the saponins in the purified extract of M. charantia. It was found that there were four kinds of saponins in the extract of M. charantia: kuguaglycoside A, momordicoside L, kuguacin B and kuguacin J, providing a basis for the study of the biological activity of saponins.

Up-To-Date Analysis of the Extraction Methods for Anthocyanins: Principles of the Techniques, Optimization, Technical Progress, and Industrial Application

Nowadays, food industries are concerned about satisfying legal requirements related to waste policy and environmental protection. In addition, they take steps to ensure food safety and quality products that have high nutritional properties. Anthocyanins are considered high added-value compounds due to their sensory qualities, colors, and nutritional properties; they are considered bioactive ingredients. They are found in high concentrations in many by-products across the food industry. Thus, the non-conventional extraction techniques presented here are useful in satisfying the current food industry requirements. However, selecting more convenient extraction techniques is not easy. Multiple factors are implicated in the decision. In this review, we compile the most recent applications (since 2015) used to extract anthocyanins from different natural matrices, via conventional and non-conventional extraction techniques. We analyze the main advantages and disadvantages of anthocyanin extraction techniques from different natural matrices and discuss the selection criteria for sustainability of the processes. We present an up-to-date analysis of the principles of the techniques and an optimization of the extraction conditions, technical progress, and industrial applications. Finally, we provide a critical comparison between these techniques and some recommendations, to select and optimize the techniques for industrial applications.

A targeted extraction with solvent-free pressurized method based on analyte-like oxonium salts: An example for simultaneous determination of bamboo-leaf flavonoids by ultra-performance liquid chromatography/ultraviolet detection

By using novel oxonium salts in "Sandwich" mode, an improved approach of targeted enrichment through a pressurized solvent-free extraction coupled with ultra-performance liquid chromatography/ultraviolet detection (UPLC-UV) analysis was developed for main bioactive flavonoids in bamboo leaves. As solid extractants, these salts have the same structural nucleus with analytes. By comparison, the yield of this new method was higher than that of reported ways, and the highest enrichment factor reached 394.22. The whole process was more consistent with pseudo-second order model (R²=0.9994) with the rate constant of 0.0537 (g/mg·min). Moreover, ideal selectivity, linearity, repeatability, limit of detection, limit of quantification, and recovery were all achieved.

An Efficient Ionic Liquid-Mediated Extraction and Enrichment of Isoimperatorin from Ostericum koreanum (Max.) Kitagawa

Ionic liquids (ILs) have attracted significant interest because of their desirable properties. These characteristics have improved their application to overcome the shortcomings of conventional separation techniques for phytochemicals. In this study, several ILs were investigated for their capacity to extract isoimperatorin, a bioactive furanocoumarin, from the roots of Ostericum koreanum. Herein, 1-Butyl-3-methylimidazolium tetrafluoroborate ([Bmim][BF4]) was selected as a promising IL for separating isoimperatorin. A central composite design was applied to optimize the extraction conditions. Under the optimal conditions, the yield of isoimperatorin reached 97.17 ± 1.84%. Additionally, the recovery of isoimperatorin from the [Bmim][BF4] solution was successfully achieved (87.73 ± 2.37%) by crystallization using water as an antisolvent. The purity of the isoimperatorin was greatly enhanced, from 0.26 ± 0.28% in the raw material to 26.94 ± 1.26% in the product, in a one-step crystallization process. Namely, an enhancement of approximately 103-folds was reached. The developed approach overcomes the shortcomings of conventional separation methods applied for gaining isoimperatorin by significantly reducing the laboriousness of the process and the consumption of volatile organic solvents. Moreover, the simplicity and effectiveness of the method are assumed to be valuable for producing isoimperatorin-enriched products and for promoting its purification. This work also confirms the efficiency of ILs as a promising material for the separation of phytochemicals.

Facile and Rapid Isolation of Oxypeucedanin Hydrate and Byakangelicin from Angelica dahurica by Using [Bmim]Tf2N Ionic Liquid

Ionic liquids (ILs) have sparked much interest as alternative solvents for plant materials as they provide distinctive properties. Therefore, in this study, the capacity of ILs to extract oxypeucedanin hydrate and byakangelicin from the roots of Angelica dahurica (A. dahurica) was investigated. The back-extraction method was examined to recover target components from the IL solution as well. Herein, [Bmim]Tf2N demonstrated outstanding performance for extracting oxypeucedanin hydrate and byakangelicin. Moreover, factors including solvent/solid ratio, extraction temperature and time were investigated and optimized using a statistical approach. Under optimum extraction conditions (solvent/solid ratio 8:1, temperature 60 °C and time 180 min), the yields of oxypeucedanin hydrate and byakangelicin were 98.06% and 99.52%, respectively. In addition, 0.01 N HCl showed the most significant ability to back-extract target components from the [Bmim]Tf2N solution. The total content of both oxypeucedanin hydrate (36.99%) and byakangelicin (45.12%) in the final product exceeded 80%. Based on the data, the proposed approach demonstrated satisfactory extraction ability, recovery and enrichment of target compounds in record time. Therefore, the developed approach is assumed essential to considerably reduce drawbacks encountered during the separation of oxypeucedanin hydrate and byakangelicin from the roots of A. dahurica.

Efficient Extraction of Anti-Inflammatory Active Ingredients from Schefflera octophylla Leaves Using Ionic Liquid-Based Ultrasonic-Assisted Extraction Coupled with HPLC

Schefflera octophylla (Lour.) Harms, a kind of traditional Chinese medicine (TCM), is commonly used for anti-inflammatory, analgesic, rheumatism, fever, and hemostasis therapy. In our previous studies, two major triterpenoids were isolated and identified from leaves of S. octophylla, and evaluated for their inhibitory effects on lipopolysaccharide (LPS)-induced nitric oxide production in RAW264.7 cells; both of them displayed significant anti-inflammatory activities at their noncytotoxic concentrations. Therefore, it is very useful to establish an efficient and green extraction method to isolated the two major triterpenoids from leaves of S. octophylla. In this paper, ionic liquid based ultrasonic-assisted extraction (ILUAE) was successfully applied to extract the two major triterpenoids from leaves of S. octophylla. Four single factors (ionic liquids (ILs) concentration, solid–liquid ratio, centrifugal speed, mesh number), with a greater impact on extraction rate, were selected from a variety of influencing factors, and the optimal conditions were obtained by Box–Behnken response surface methodology (RSM). Under optimal conditions, the total extraction yield and extraction rate of two triterpenoids were 288.03 mg/g and 28.80%, respectively, which was 6.80% higher than that of 70% Ethanol (220 mg/g and 22%, respectively).

Rapid and Efficient Separation of Decursin and Decursinol Angelate from Angelica gigas Nakai using Ionic Liquid, (BMIm)BF4, Combined with Crystallization

Ionic liquids (ILs) have gained much attention as alternative solvents to volatile organic solvents due to their attractive properties. This study aimed to develop an efficient method for the selective separation of decursin (D) and decursinol angelate (DA) from Angelica gigas Nakai (A. gigas) using ILs and crystallization. The IL 1-butyl-3-methylimidazolium tetrafluoroborate ((BMIm)BF₄) was the most efficient at extracting D and DA. Parameters including solid-to-liquid ratio, time, and temperature were optimized by response surface methodology (RSM). Under optimal extraction conditions (1 g/6.5 mL solid-to-liquid ratio, 60 °C temperature, and 120 min time), the extraction yields of D and DA were 43.32 mg/g (97.06%) and 17.87 mg/g (97.12%), respectively. Moreover, drowning out crystallization using deionized water (DW) as an anti-solvent offered an excellent ability to recover D and DA from the A. gigas–(BMIm)BF₄ extraction solution. The rates of recovery and the total purity of D and DA were found to be greater than 97%. Therefore, a rapid and efficient method of combining ILs with crystallization was effectively achieved for the selective separation of D and DA. This approach is assumed to be beneficial in the pharmaceutical industry for the effective obtention of D- and DA-enriched products.

Ionic Liquid Solutions as a Green Tool for the Extraction and Isolation of Natural Products

In the past few years, the application of ionic liquids (ILs) had attracted more attention of the researchers. Many studies focused on extracting active components from traditional herbals using ILs as alternative solvents so as to address the issue caused by the traditional methods for extraction of natural products (NPs) with organic chemical reagents. Through the summary of reported research work, an overview was presented for the application of ILs or IL-based materials in the extraction of NPs, including flavonoids, alkaloids, terpenoids, phenylpropanoids and so on. Here, we mainly describe the application of ILs to rich the extraction of critical bioactive constituents that were reported possessing multiple therapeutic effects or pharmacological activities, from medicinal plants. This review could shed some light on the wide use of ILs in the field of natural products chemistry to further reduce the environmental damage caused by large quantity of organic chemical reagents.

Quality Evaluation of Apocyni Veneti Folium from Different Habitats and Commercial Herbs Based on Simultaneous Determination of Multiple Bioactive Constituents Combined with Multivariate Statistical Analysis

Apocyni Veneti Folium (AVF) is a kind of staple traditional Chinese medicine with vast clinical consumption because of its positive effects. However, due to the habitats and adulterants, its quality is uneven. To control the quality of this medicinal herb, in this study, the quality of AVF was evaluated based on simultaneous determination of multiple bioactive constituents combined with multivariate statistical analysis. A reliable method based on ultra-fast liquid chromatography tandem triple quadrupole mass spectrometry (UFLC-QTRAP-MS/MS) was developed for the simultaneous determination of a total of 43 constituents, including 15 flavonoids, 6 organic acids, 13 amino acids, and 9 nucleosides in 41 Luobumaye samples from different habitats and commercial herbs. Furthermore, according to the contents of these 43 constituents, principal component analysis (PCA) was employed to classify and distinguish between AVF and its adulterants, leaves of Poacynum hendersonii (PHF), and gray relational analysis (GRA) was performed to evaluate the quality of the samples. The proposed method was successfully applied to the comprehensive quality evaluation of AVF, and all results demonstrated that the quality of AVF was higher than the PHF. This study will provide comprehensive information necessary for the quality control of AVF.

Ionic-Liquid-Mediated Extraction and Separation Processes for Bioactive Compounds: Past, Present, and Future Trends

Ionic liquids (ILs) have been proposed as promising media for the extraction and separation of bioactive compounds from the most diverse origins. This critical review offers a compilation on the main results achieved by the use of ionic-liquid-based processes in the extraction and separation/purification of a large range of bioactive compounds (including small organic extractable compounds from biomass, lipids, and other hydrophobic compounds, proteins, amino acids, nucleic acids, and pharmaceuticals). ILs have been studied as solvents, cosolvents, cosurfactants, electrolytes, and adjuvants, as well as used in the creation of IL-supported materials for separation purposes. The IL-based processes hitherto reported, such as IL-based solid-liquid extractions, IL-based liquid-liquid extractions, IL-modified materials, and IL-based crystallization approaches, are here reviewed and compared in terms of extraction and separation performance. The key accomplishments and future challenges to the field are discussed, with particular emphasis on the major lacunas found within the IL community dedicated to separation processes and by suggesting some steps to overcome the current limitations.

Optimization of Ionic Liquid-Assisted Extraction of Biflavonoids from Selaginella doederleinii and Evaluation of Its Antioxidant and Antitumor Activity

As new green solvents, ionic liquids (ILs) have been generally applied in the extraction and separation of natural product. In this study, microwave assisted extraction based on IL (IL-MAE) was firstly employed to extract total biflavonoids from Selaginella doederleinii. Based on single-factor experiment, microwave power (300–700 W), extract time (30–50 min) and extract temperature (40–60 °C) on total bioflavonoids and antioxidant activities of the extracts were further investigated by a Box-Behnken design of response surface methodology (RSM) selecting total bioflavonoids yields and IC₅₀ of radical scavenging as index. Besides antioxidant activity of the extract was evaluated by a 2,2-diphenyl-1-picrylhydarzyl (DPPH) and 2,2′-azinobis-(3-ethylbenzthiazoline-6-sulphonate (ABTS) radical scavenging assay, ferric reducing power assay and chelation of ferrous ions assay, and then anticaner activity was also researched against A549 cell line and 7721 cell line. The results illustrated that three factors and their interactions could be well suited for second-order polynomial models (p < 0.05). Through process parameters, optimization of the extract (460 W, 40 min, and 45 °C) and detection of bioactivity, the yield of total bioflavonoids was 16.83 mg/g and IC₅₀ value was 56.24 μg/mL, respectively, indicating the extract has better anti-oxidation effect and antitumor activity. Furthermore, IL-MAE was the most efficient extracting method compared with MAE and Soxhlet extraction, which could improve extraction efficiency in a shorter time and at a lower temperature. In general, ILs-MAE was first adopted to establish a novel and green extraction process on the yields of total biflavonoids from S. doederleinii. In addition, the extract of containing biflavones showed potent antioxidant and anticancer capacity as a utilized valuable bioactive source for natural medicine.

Natural Antioxidants in Foods and Medicinal Plants: Extraction, Assessment and Resources

Natural antioxidants are widely distributed in food and medicinal plants. These natural antioxidants, especially polyphenols and carotenoids, exhibit a wide range of biological effects, including anti-inflammatory, anti-aging, anti-atherosclerosis and anticancer. The effective extraction and proper assessment of antioxidants from food and medicinal plants are crucial to explore the potential antioxidant sources and promote the application in functional foods, pharmaceuticals and food additives. The present paper provides comprehensive information on the green extraction technologies of natural antioxidants, assessment of antioxidant activity at chemical and cellular based levels and their main resources from food and medicinal plants.