Application of an efficient strategy based on liquid-liquid extraction, high-speed counter-current chromatography, and preparative HPLC for the rapid enrichment, separation, and purification of four anthraquinones fromRheum tanguticum

Rhei Radix et Rhizoma and its anthraquinone derivatives: Potential candidates for pancreatitis treatment

BACKGROUND

Pancreatitis is a common exocrine inflammatory disease of the pancreas and lacks specific medication currently. Rhei Radix et Rhizoma (RR) and its anthraquinone derivatives (AQs) have been successively reported for their pharmacological effects and molecular mechanisms in experimental and clinical pancreatitis. However, an overview of the anti-pancreatitis potential of RR and its AQs is limited.

PURPOSE

To summarize and analyze the pharmacological effects of RR and its AQs on pancreatitis and the underlying mechanisms, and discuss their drug-like properties and future perspectives.

METHODS

The articles related to RR and its AQs were collected from the Chinese National Knowledge Infrastructure, Wanfang data, PubMed, and the Web of Science using relevant keywords from the study's inception until April first, 2024. Studies involving RR or its AQs in cell or animal pancreatitis models as well as structure-activity relationship, pharmacokinetics, toxicology, and clinical trials were included.

RESULTS

Most experimental studies are based on severe acute pancreatitis rat models and a few on chronic pancreatitis. Several bioactive anthraquinone derivatives of Rhei Radix et Rhizoma (RRAQs) exert local protective effects on the pancreas by maintaining pancreatic acinar cell homeostasis, inhibiting inflammatory signaling, and anti-fibrosis, and they improve systemic organ function by alleviating intestinal and lung injury. Pharmacokinetic and toxicity studies have revealed the low bioavailability and wide distribution of RRAQs, as well as hepatotoxicity and nephrotoxicity. However, there is insufficient research on the clinical application of RRAQs in pancreatitis. Furthermore, we propose effective strategies for subsequent improvement in terms of balancing effectiveness and safety.

CONCLUSION

RRAQs can be developed as either candidate drugs or novel lead structures for pancreatitis treatment. The comprehensive review of RR and its AQs provides references for optimizing drugs, developing therapies, and conducting future studies on pancreatitis.

Preparative Fractionation of Brazilian Red Propolis Extract Using Step-Gradient Counter-Current Chromatography

Propolis is a resinous bee product with a very complex composition, which is dependent upon the plant sources that bees visit. Due to the promising antimicrobial activities of red Brazilian propolis, it is paramount to identify the compounds responsible for it, which, in most of the cases, are not commercially available. The aim of this study was to develop a quick and clean preparative-scale methodology for preparing fractions of red propolis directly from a complex crude ethanol extract by combining the extractive capacity of counter-current chromatography (CCC) with preparative HPLC. The CCC method development included step gradient elution for the removal of waxes (which can bind to and block HPLC columns), sample injection in a single solvent to improve stationary phase stability, and a change in the mobile phase flow pattern, resulting in the loading of 2.5 g of the Brazilian red propolis crude extract on a 912.5 mL Midi CCC column. Three compounds were subsequently isolated from the concentrated fractions by preparative HPLC and identified by NMR and high-resolution MS: red pigment, retusapurpurin A; the isoflavan 3(R)-7-O-methylvestitol; and the prenylated benzophenone isomers xanthochymol/isoxanthochymol. These compounds are markers of red propolis that contribute to its therapeutic properties, and the amount isolated allows for further biological activities testing and for their use as chromatographic standards.

High-speed counter-current chromatography assisted preparative isolation of phenolic compounds from the flowers of Chrysanthemum morifolium cv. Fubaiju

Chrysanthemum morifolium cv. Fubaiju is rich in phenolic compounds with various benefits such as anti-inflammatory, antioxidant, and cardiovascular protection. In this study, 12 phenolic compounds, including five flavonoid glycosides and seven quinic acid derivatives, were successfully separated from the flowers of Chrysanthemum morifolium cv. Fubaiju by high-speed counter-current chromatography and preparative high-performance liquid chromatography. Ethyl acetate-n-butanol-acetonitrile-water-acetic acid (5:0.5:2.5:5:0.25, v/v/v/v/v) was selected as solvent system to separate six fractions from the flowers of Chrysanthemum morifolium cv. Fubaiju, and 20% aqueous acetonitrile (containing 0.1% formic acid) was chosen to be the elution solvent in preparative high-performance liquid chromatography for purifying the fractions above. Luteolin-7-O-β-D-glucoside (1), luteolin-7-O-β-D-glucuronide (2), apigenin-7-O-β-D-glucoside (3), luteolin-7-O-β-D-rutinoside (4), diosmetin-7-O-β-D-glucoside (5), chlorogenic acid (6), 1,5-dicaffeoylquinic acid (7), 1,4-dicaffeoylquinic acid (8), 3,4-dicaffeoylquinic acid (9), 3,4-dicaffeoyl-epi-quinic acid (10), 3,5-dicaffeoylquinic acid (11), and 4,5-dicaffeoylquinic acid (12) were isolated with purities all above 95%, respectively. In addition, all isolates were evaluated for their protective effects on H2 O2 -induced oxidative damage in adult retinal pigment epithelial cells.

Facile and selective separation of anthraquinones by alizarin-modified iron oxide magnetic nanoparticles

Anthraquinones are widely distributed in higher plants and possess broad biological activities. The conventional separation procedures for isolating anthraquinones from the plant crude extracts require multiple extraction, concentration, and column chromatography steps. In this study, we synthesized three alizarin (AZ)-modified Fe₃O₄ nanoparticles (Fe₃O₄@AZ, Fe₃O₄@SiO₂-AZ, and Fe₃O₄@SiO₂-PEI-AZ) by thermal solubilization method. Fe₃O₄@SiO₂-PEI-AZ showed strong magnetic responsiveness, high methanol/water dispersion, good recyclability, and high loading capacity for anthraquinones. To evaluate the feasibility of using Fe₃O₄@SiO₂-PEI-AZ for separating various aromatic compounds, we employed molecular dynamics simulations to predict the adsorption/desorption effects of PEI-AZ for various aromatic compounds in different methanol concentrations. The results showed that the anthraquinones could be efficiently separated from the monocyclic and bicyclic aromatic compounds by adjusting the methanol/water ratio. The Fe₃O₄@SiO₂-PEI-AZ nanoparticles were then used to separate the anthraquinones from the rhubarb extract. At 5% methanol, all the anthraquinones were adsorbed by the nanoparticles, thus allowing their separation from other components in the crude extract. Compared with the conventional separation methods, this adsorption method has the advantages of high adsorption specificity, simple operation, and solvent saving. This method sheds light on the future application of functionalized Fe₃O₄ magnetic nanoparticles to selectively separate desired components from complex plant and microbial crude extracts.

Preparation of magnetic metal-organic framework MIL-101(Fe) and its application in the extraction of anthraquinones in rhubarb

In this work, a magnetic octahedral metal organic framework (Fe₃ O₄ @NH₂ -MIL-101(Fe)) was synthesized for the magnetic solid phase extraction of three anthraquinones, including aloe-emodin, emodin, and physcion, in rhubarb. The Fe₃ O₄ @NH₂ -MIL-101(Fe) exhibited a high specific surface area of 259.2 m² /g with an average pore size of 6.0 nm and a high magnetic responsivity of 23.4 emu/g, which may be used as an adsorbent for rapid preconcentration and separation of target analytes. The main parameters for magnetic solid phase extraction of anthraquinones, including the amount of adsorbent, extraction time, extraction temperature, extraction pH, elution solvent, and elution time, were systematically optimized. The whole extraction process required a very low amount of adsorbent and a small volume of the sample. Besides, under the optimized conditions, the method showed satisfactory spiked recovery for anthraquinones in the range of 93.3%-109.1%, and the LODs were 1.7-3.4 ng/mL. The RSDs for intra- and inter- day precision were 0.2%-1.3% and 0.2%-0.6%, respectively. The experimental results indicate that the developed method is feasible for the analysis of anthraquinones in rhubarb. This article is protected by copyright. All rights reserved.

Review of ultrasound combinations with hybrid and innovative techniques for extraction and processing of food and natural products

Ultrasound has a significant effect on the rate of various processes in food, perfume, cosmetic, pharmaceutical, bio-fuel, materials, or fine chemical industries, despite some shortcomings. Combination with other conventional or innovative techniques can overcome these limitations, enhance energy, momentum and mass transfer, and has been successfully demonstrated in many recent studies. Various ultrasound combined hybrid and innovative techniques are systematically summarized in this review for the first time. Ultrasound can be combined with diverse conventional techniques including Soxhlet, Clevenger, enzyme, hydrotropes, ionic liquids, Deep Eutectic Solvents (DES) or Natural Deep Eutectic Solvents (NADES), to enhance mixing and micro-mixing, reduced thermal and concentration gradients, and selective extraction. Moreover, combinations of ultrasound with other innovative techniques such as microwave, extrusion, supercritical fluid, subcritical and pressure liquids, Instant controlled pressure drop (DIC), Pulsed Electric Field (PEF), Ultra-Violet (UV) or Infra-Red (IR) radiations, Counter-current chromatography (CCC), or centrifugal partition chromatographs (CPC) can enable reduced equipment size, faster response to process control, faster start-up, increased production, and elimination of process steps. The theories and applications of these ultrasound combined hybrid and innovative techniques as well as their advantages and limitations are compared, and further perspectives are proposed. This review provides new insights into advances in ultrasound combined techniques and their application at research, educational, and industrial level in modern food and plant-based chemistry.

Separation of the Glycosylated Carotenoid Myxoxanthophyll from Synechocystis Salina by HPCCC and Evaluation of Its Antioxidant, Tyrosinase Inhibitory and Immune-Stimulating Properties

Global demand for natural pigments has increased in the past few years. Myxoxanthophyll, a glycosylated monocyclic carotenoid, is a pigment that occurs naturally in cyanobacteria but no scalable isolation process has been developed to obtain it from its natural source to date. In this study, myxoxanthophyll was isolated from unicellular cyanobacterium Synechocystis salina (S. salina) using high-performance countercurrent chromatography (HPCCC), where the lower phase of the biphasic solvent system composed of n-heptane–ethanol–water (2:4:4, v/v/v) was used as a mobile phase, whereas its upper phase was the stationary phase. For the HPCCC isolation, a multi-injection method was developed, and four consecutive sample injections (70 mg each) were performed, obtaining, in total, 20 mg of myxoxanthophyll, which was finally purified with high-performance liquid chromatography (HPLC). Overall, a final myxoxanthophyll yield of 15 mg (98% purity) was obtained. The target pigment showed a weak antioxidant and tyrosinase inhibitory effect, and exhibited immune-stimulating properties by activating human granulocytes. The results presented here form a basis for the large-scale production of myxoxanthophyll, and show the potential benefits of this pigment for human health.

Isolation and Purification of Kudinosides from Kuding Tea by Semi-Preparative HPLC Combined with MCI-GEL Resin

Background:

Kuding tea, a Traditional Chinese drink, has a history of thousands of years in China. Triterpenoid saponins in Kuding tea are regarded as one of the major functional ingredients.

Objective:

The aim of this paper was to establish separation progress for the isolation and purification of five triterpenoid saponins (kudinoside A, C, D, F, G) from Kuding tea.

Methods:

Nine types of resins, including seven macroporous resins and two MCI-GEL resins, were firstly used for purifying triterpenoid saponins by the adsorption and desorption tests. Further dynamic adsorption/desorption experiments were carried out to obtain the optimal parameters for the five targeted saponins. Then the purification of five triterpenoid saponins (kudinoside A, C, D, F, G) was completed by semi-preparative high-performance liquid chromatography (semi-pHPLC).

Results:

As of optimized results, the HP20SS MCI-GEL was selected as the optimal one. The data also showed that 65.24 mg of refined extract including 7.04 mg kudinoside A, 3.52 mg kudinoside C, 4.04 mg kudinoside D, 4.13 mg kudinoside F, and 34.45 mg kudinoside G, could be isolated and purified from 645.90 mg of crude extract in which the content of five saponins was 81.51% and the average recovery reached 69.76%. The final contents of five saponins increased 6.91-fold as compared to the crude extract.

Conclusion:

The established separation progress was highly efficient, making it a potential approach for the large-scale production in the laboratory and providing several markers of triterpenoid saponins for quality control of Kuding tea or its processing products.

Isolation of six anthraquinone diglucosides from cascara sagrada bark by high-performance countercurrent chromatography

In this study, high-performance countercurrent chromatography was employed to isolate six anthraquinone diglucosides, namely, cascarosides A-F, from cascara sagrada (Rhamnus purshiana DC [Rhamnaceae]) bark. The n-butanol-soluble extract of cascara sagrada was separated by off-line two-dimensional high-performance countercurrent chromatography. The first-dimensional high-performance countercurrent chromatography resolved the n-butanol-soluble extract (510 mg) of cascara sagrada using the flow-rate gradient method with a chloroform-methanol-isopropanol-water (6:6:1:4, v/v/v/v, normal-phase mode) system to afford four anthraquinone diglucoside fractions (groups I [cascarosides C-D, 71 mg], II [cascarosides E-F, 56 mg], III [cascaroside A, 53 mg], and IV [cascaroside B, 31 mg]). Groups I and II were separated by the second-dimensional high-performance countercurrent chromatography using an ethyl acetate-n-butanol-water (7:3:10, v/v/v, normal-phase mode) system to yield cascarosides C (34 mg), D (26 mg), E (19 mg), and F (15 mg). Additionally, one-step preparative-scale high-performance countercurrent chromatography method was developed to isolate large amounts of cascarosides A (389 mg) and B (187 mg) from the water-soluble extract (2.1 g) of cascara sagrada using an ethyl acetate-n-butanol-water (2:8:10, v/v/v, normal-phase mode) system. The current study demonstrated that high-performance countercurrent chromatography is a powerful technique for the isolation of marker compounds from herbal materials.

Identification of Transient Receptor Potential Vanilloid 3 Antagonists from Achillea alpina L. and Separation by Liquid-Liquid-Refining Extraction and High-Speed Counter-Current Chromatography

Bioassay-guided fractionation of the ethanol extract of whole herbs of Achilleaalpina led to the isolation of isochlorogenic acids A and B as transient receptor potential vanilloid 3 (TRPV3) channel antagonists by using a calcium fluorescent assay. The structures were identified by spectroscopic analysis and the inhibitory activities of isochlorogenic acids A and B were confirmed by whole-cell patch clamp recordings of human embryonic kidney 293 (HEK293) cells expressing human TRPV3. Molecular docking results revealed that these two compounds reside in the same active pocket of human TRPV3 channel protein with lower binding energy than the agonist 2-aminoethoxydiphenyl borate (2-APB). High-speed counter-current chromatography (HSCCC) coupled with a liquid-liquid extraction approach was successfully established for the separation of isochlorogenic acids A and B from the whole herbs of A. alpina. Ethyl acetate and n-hexane-ethyl acetate-water (3:3:4 and 1:5:4, v/v/v) were selected as liquid-liquid extraction solvent systems to remove high- and low-polarity impurities in the mixture. Sixty g of ethanol extract was refined by solvent partition to yield 1.7 g of the enriched fraction, of which 480 mg in turn obtained 52.5 mg of isochlorogenic acid B (purity 98.3%) and 37.6 mg isochlorogenic acid A (purity 96.2%) after HSCCC with n-hexane-ethyl acetate-water containing 1% acetic acid (1:4:8, v/v/v).

Rapid identification of Streptomyces tetracycline producers by MALDI-TOF mass spectrometry

The main objective of this study was using matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS) for assembling of DSM (German Collection of Microorganisms) Streptomyces spectral database and identification of wild Streptomyces cultures, which were clustered by MALDI-TOF Biotyper OC software as well as for teracycline detection by observing of obtained spectra using flexAnalysis software. Production of tetracycline was confirmed by thin-layer chromatography. Presence of tetracycline mass spectrum was verified by several tetracycline producers (Streptomyces aureofaciens LMG 5968, S. aureofaciens 84/25, and S. aureofaciens BMK) and by pure tetracycline mass. Our results showed that it is possible to use MALDI-TOF MS for identification of tetracycline producers within Streptomyces genera by several easy steps. The purpose of this study was to establish cheap and quick detection of tetracycline producers.

Identification and Quantification of Four Anthraquinones in Rhubarb and its Preparations by Gas Chromatography-Mass Spectrometry

A gas chromatographic-mass spectrometric (GC-MS) method was developed for the determination of four anthraquinones found in rhubarb. Chrysophanol, physcion, aloe-emodin and emodin were confirmed by GC-MS and the possible main cleavage pathways of fragment ions are discussed in this study. Rhubarb is a traditional Chinese medicinal herb which required an effective evaluation method to quantitate the four major active anthraquinone compounds described. The determinations of analytes were accomplished by GC-MS using osthole as an internal standard. MS detection was performed in selected ion monitoring mode to increase the sensitivity. The method was evaluated by a number of validation characteristics (precision, limit of detection, calibration range and recovery). The calibration ranges were all 3.2-30.0 μg/mL. This method was fully validated and showed good performances in terms of recovery (96.9-102.9%) and precision (1.4-2.9%). Finally, the method was applied to the analysis of four anthraquinones in rhubarb and its preparations in the first time.

Isolation and purification of two antioxidant isomers of resveratrol dimer from the wine grape by counter-current chromatography

Resveratrol dimers belong to a group of compounds called stilbenes, which along with proanthocyanidins, anthocyanins, catechins, and flavonols are natural phenolic compounds found in grapes and red wine. Stilbenes have a variety of structural isomers, all of which exhibit various biological properties. Counter-current chromatography with a two-phase solvent system composed of n-hexane/ethyl acetate/methanol/water (2:5:4:5, v/v/v/v) was applied to isolate and purify stilbene from the stems of wine grape. Two isomers of resveratrol dimers trans-ε-viniferin and trans-δ-viniferin were obtained from the crude sample in a one-step separation, with purities of 93.2 and 97.5%, respectively, as determined by high-performance liquid chromatography. The structures of these two compounds were identified by (1) H and (13) C NMR spectroscopy. In addition, their antioxidant activities were assessed by 1,1-diphenyl-2-picrylhydrazyl (DPPH) assay. The antioxidant activities of trans-δ-viniferin were higher than that of trans-ε-viniferin in this model. This work demonstrated that counter-current chromatography is a powerful and effective method for the isolation and purification of polyphenols from wine grape. Additionally, the DPPH radical assay showed that the isolated component trans-δ-viniferin exhibited stronger antioxidant activities than trans-ε-viniferin and a little bit weaker than vitamin E at the same concentration.

SPE-UHPLC-FLD Method for the Simultaneous Determination of Five Anthraquinones in Human Urine Using Mixed-Mode Bis(tetraoxacalix[2]arene[2]triazine) Modified Silica as Sorbent

The five anthraquinones compounds (including aloe-emodin, emodin, physcion, chrysophanol, and rhein) are regarded as the main effective ingredients in rhubarb (Dahuang in Chinese, one of the commonly used Chinese herbal medicines). In this work, a simple and effective solid phase extraction (SPE) method based on bis(tetraoxacalix[2]arene[2]triazine) modified silica gel as adsorbent was developed. Coupled with UHPLC-FLD, the developed method was successfully applied for the measuring of main anthraquinones in human urine after oral administration of the extracts of rhubarb. To obtain the highest recoveries of the five anthraquinones in the SPE process, the main parameters which may affect extraction efficiency were optimized. The optimized sorbent amount, sample loading pH, sample loading rate, washing solution, and eluent condition were obtained. The developed method showed good linearity in 0.012-1.800 μg mL-1 for the five anthraquinones with correlation coefficients more than 0.9993. The investigated LOD values ranged from 3.9 to 5.7 ng mL-1, while the LOQs were between 12.0 and 18.2 ng mL-1. The recoveries of the method were also investigated, which were in the range of 94.8-106.6%. The application of the mixed-mode SPE materials in the proposed method was feasible and simple, and suitable for the enrichment of anthraquinones in urine samples.

Antibacterial activity of isolated phenolic compounds from cranberry (Vaccinium macrocarpon) against Escherichia coli

Phenolic compounds from a cranberry extract were isolated in order to assess their contribution to the antibacterial activity against uropathogenic strains of Escherichia coli (UPEC). With this purpose, a total of 25 fractions from a cranberry extract were isolated using semipreparative high performance liquid chromatography (HPLC) and characterized based on the results obtained by reversed-phase HPLC coupled to mass spectrometry detection. Then, the effects on UPEC surface hydrophobicity and biofilm formation of the cranberry extract as well as the purest fractions (a total of 13) were tested. As expected, the whole extract presented a powerful antibacterial activity against UPEC while the selected fractions presented a different behavior. Myricetin and quercitrin significantly decreased (p < 0.05) E. coli biofilm formation compared with the control, while dihydroferulic acid glucuronide, procyanidin A dimer, quercetin glucoside, myricetin and prodelphinidin B led to a significant decrease of the surface hydrophobicity compared with the control. The results suggest that apart from proanthocyanidins, other compounds, mainly flavonoids, can act against E. coli biofilm formation and also modify UPEC surface hydrophobicity in vitro, one of the first steps of adhesion.

Separation of three anthraquinone glycosides including two isomers by preparative high-performance liquid chromatography and high-speed countercurrent chromatography from Rheum tanguticum Maxim. ex Balf

Anthraquinone glycosides, such as chrysophanol 1-O-β-d-glucoside, chrysophanol 8-O-β-d-glucoside, and physion 8-O-β-d-glucoside, are the accepted important active components of Rheum tanguticum Maxim. ex Balf. due to their pharmacological properties: antifungal, antimicrobial, cytotoxic, and antioxidant activities. However, an effective method for the separation of the above-mentioned anthraquinone glycosides from this herb is not currently available. Especially, greater difficulty existed in the separation of the two isomers chrysophanol 1-O-β-d-glucoside and chrysophanol 8-O-β-d-glucoside. This study demonstrated an efficient strategy based on preparative high-performance liquid chromatography and high-speed countercurrent chromatography for the separation of the above-mentioned anthraquinone glycosides from Rheum tanguticum Maxim.ex Balf.

Development of "ultrasound-assisted dynamic extraction" and its combination with CCC and CPC for simultaneous extraction and isolation of phytochemicals

A new method for the extraction of medicinal herbs termed ultrasonic-assisted dynamic extraction (UADE) was designed and evaluated. This technique was coupled with counter-current chromatography (CCC) and centrifugal partition chromatography (CPC) and then applied to the continuous extraction and online isolation of chemical constituents from Paeonia lactiflora Pall (white peony) roots. The mechanical parameters, including the pitch and diameter of the shaft, were optimized by means of mathematical modeling. Furthermore, the configuration and mechanism of online UADE coupled with CCC and CPC were elaborated. The stationary phases of the two-phase solvent systems from CCC and CPC were utilized as the UADE solution. The extraction solution was pumped into the sample loop and then introduced into the CCC column; the target compounds were eluted with the lower aqueous phase of the two-phase solvent system. During the CCC separation, the extraction solution was continuously fed in the sample loop by turning the ten-port valve; the extraction solution was then pumped into the CPC column and eluted by the mobile phase of the two-phase solvent system mentioned above. When the first cycle of the UADE/CCC/CPC was completed, the second cycle experiment could be carried out, and so on. Four target compounds (albiflorin, benzoylpaeoniflorin, paeoniflorin, and galloylpaeoniflorin) with purities above 94.96% were successfully extracted and isolated online using the two-phase solvent system comprising ethyl acetate-n-butanol-ethanol-water (1:3.5:2:4.5, v/v/v/v). Compared with conventional extraction methods, the instrumental setup of the present method offers the advantages of automation and systematic extraction and isolation of natural products.

Development of a method to screen and isolate potential α-glucosidase inhibitors from Panax japonicus C.A. Meyer by ultrafiltration, liquid chromatography, and counter-current chromatography

A new assay based on ultrafiltration, liquid chromatography and mass spectrometry was developed for the rapid screening and identification of the ligands for α-glucosidase from the extract of Panax japonicus. Six saponins were identified as α-glucosidase inhibitors. Subsequently, the specific binding ligands, namely, notoginsenoside R1 , ginsenoside Rb1 , chikusetsusaponin V, chikusetsusaponin IV, chikusetsusaponin IVa, and ginsenoside Rd (the purities were 94.18, 95.43, 96.09, 93.26, 94.50, 93.86%, respectively) were separated by counter-current chromatography using two-phase solvent systems composed of tert-butyl methyl ether, acetonitrile, 0.1% aqueous formic acid (3.8:1.0:4.4, v/v/v) and the solvent system composed of methylene chloride, isopropanol, methanol, 0.1% aqueous formic acid (5.8:1.0:6.0:2.2, v/v/v). The results demonstrate that ultrafiltration, liquid chromatography and mass spectrometry combined with high-speed counter-current chromatography might provide not only a powerful tool for screening and isolating α-glucosidase inhibitors in complex samples but also a useful platform for discovering bioactive compounds for the prevention and treatment of diabetes mellitus.

Separation of flavonoids from Millettia griffithii with high-performance counter-current chromatography guided by anti-inflammatory activity

Millettia griffithii is a unique Chinese plant located in the southern part of Yunnan Province. Up to now, there is no report about its phytochemical or related bioactivity research. In our previous study, the n-hexane crude extract of Millettia griffithii revealed significant anti-inflammatory activity at 100 μg/mL, inspiring us to explore the anti-inflammatory constituents. Four fractions (I, II, III, and A) were fractionated from n-hexane crude extract by high-performance counter-current chromatography with solvent system composed of n-hexane/ethyl acetate/methanol/water (8:9:8:9, v/v) and then were investigated for the potent anti-inflammatory activity. Fraction A, with the most potent inhibitory activity was further separated to give another four fractions (IV, V, VI, and B) with solvent system composed of n-hexane/ethyl acetate/methanol/water (8:4:8:4, v/v). Compound V and fraction B exhibited remarkable anti-inflammatory activity with nitric oxide inhibitory rate of 80 and 65%, which was worth further fractionation. Then, three fractions (VII, VIII, and IX) were separated from fraction B with a solvent system composed of n-hexane/ethyl acetate/methanol/water (8:1:8:1, v/v), with compound VIII demonstrating the most potent inhibitory activity (80%). Finally, the IC50 values of compound V and VIII were tested as 38.2 and 14.9 μM. The structures were identified by electrospray ionization mass spectrometry and(1)H and (13)C NMR spectroscopy.

Isolation and purification of diastereoisomeric flavonolignans from silymarin by binary-column recycling preparative high-performance liquid chromatography

Silymarin extracted from Silybum marianum (L.) Gaertn consists of a large number of flavonolignans, of which diastereoisomeric flavonolignans including silybin A and silybin B, and isosilybin A and isosilybin B are the main bioactive components, whose preparation from the crude extracts is still a difficult task. In this work, binary-column recycling preparative high-performance liquid chromatography systems without sample loop trapping, where two columns were switched alternately via one or two six-port switching valves, were established and successfully applied to the isolation and purification of the four diastereoisomeric flavonolignans from silymarin. The proposed system showed significant advantages over conventional preparative high-performance liquid chromatography with a single column in increasing efficiency and reducing the cost. To obtain the same amounts of products, the proposed system spends only one tenth of the time that the conventional system spends, and needs only one eleventh of the solvent that the conventional system consumes. Using the proposed system, the four diastereoisomers were successfully isolated from silymarin with purities over 98%.

Development of a method to extract and purify target compounds from medicinal plants in a single step: online hyphenation of expanded bed adsorption chromatography and countercurrent chromatography

Pure compounds extracted and purified from natural sources are crucial to lead discovery and drug screening. This study presents a novel two-dimensional hyphenation of expanded bed adsorption chromatography (EBAC) and high-speed countercurrent chromatography (HSCCC) for extraction and purification of target compounds from medicinal plants in a single step. The EBAC and HSCCC were hyphenated via a six-port injection valve as an interface. Fractionation of ingredients of Salvia miltiorrhiza and Rhizoma coptidis was performed on the hyphenated system to verify its efficacy. Two compounds were harvested from Salvia miltiorrhiza, one was 52.9 mg of salvianolic acid B with an over 95% purity and the other was 2.1 mg of rosmarinic acid with a 74% purity. Another two components were purified from Rhizoma coptidis, one was 4.6 mg of coptisine with a 98% purity and one was 4.1 mg of berberine with a 82% purity. The processing time was nearly 50% that of the multistep method. The results indicate that the present method is a rapid and green way to harvest targets from medicinal plants in a single step.