Alkane effect in the Arizona liquid systems used in countercurrent chromatography

Preparative separation of ten flavonoids from Scutellaria baicalensis Georgi roots using two-dimensional countercurrent chromatography with an online-storage, dilution, and mixing interface

The process of counter-current chromatography (CCC) separation for natural products typically necessitates the use of multiple solvent systems to accommodate constituents with a wide range of polarities. However, the incompatibility between these different solvent systems often results in unsuccessful online 2D successive separations. In this study, a 2D CCC system was developed, featuring an interface for online-storage, dilution, and mixing. It facilitated the implementation of online 2D CCC using different solvent systems. The method was subsequently applied for the preparative isolation of flavonoids from Scutellaria baicalensis Georgi roots. For 1D CCC, n-heptane-ethyl acetate-methanol-water (HepEMWat, 5:5:4:6, v/v) was utilized, while for 2D CCC, ethyl acetate-n-butanol-water (EBuWat, 0:5:5, v/v) was employed. The eluent with low resolution in 1D CCC was stored online, diluted three times using the lower phase of EBuWat (0:5:5, v/v), and subsequently transferred into 2D CCC for further isolation utilizing the same EBuWat (0:5:5, v/v) system. As results, six lipophilic compounds were isolated in 1D CCC in a normal mode, while two major hydrophilic constituents were isolated in a pH-peak-focusing mode in 2D CCC. Additionally, two additional compounds were purified through subsequent semi-preparative HPLC separation in order to resolve co-elution in 2D CCC. The developed 2D CCC system with a multifunctional interface demonstrated to be an exceptionally efficient and promising approach for the high-throughput purification of complex natural products.

"Sweet space" strategy for solvent system selection in countercurrent chromatography: A case study on separation of polyunsaturated fatty acids from borage oil

This study presents a comprehensive strategy for the selection and optimization of solvent systems in countercurrent chromatography (CCC) for the effective separation of compounds. With a focus on traditional organic solvent systems, the research introduces a "sweet space" strategy that merges intuitive understanding with mathematical accuracy, addressing the significant challenges in solvent system selection, a critical bottleneck in the widespread application of CCC. By employing a combination of volume ratios and graphical representations, including both regular and trirectangular tetrahedron models, the proposed approach facilitates a more inclusive and user-friendly strategy for solvent system selection. This study demonstrates the potential of the proposed strategy through the successful separation of gamma-linolenic acid, oleic acid, and linoleic acid from borage oil, highlighting the strategy's effectiveness and practical applicability in CCC separations.

Exploration of the main active metabolites from Tinospora crispa (L.) Hook. f. & Thomson stem as insulin sensitizer in L6.C11 skeletal muscle cell by integrating in vitro, metabolomics, and molecular docking

ETHNOPHARMACOLOGICAL RELEVANCE

Tinospora crispa (L.) Hook. f. & Thomson stem (TCS) has long been used as folk medicine for the treatment of diabetes mellitus. Previous study revealed that TCS possesses multi-ingredients and multi-targets characteristic potential as insulin sensitizer activity. However, its mechanisms of action and molecular targets are still obscure.

AIM OF THE STUDY

In the present study, we investigated the effects of TCS against insulin resistance in muscle cells through integrating in vitro experiment and identifying its active biomarker using metabolomics and in molecular docking validation.

MATERIALS AND METHODS

We used centrifugal partition chromatography (CPC) to isolate 33 fractions from methanolic extract of TCS, and then used UHPLC-Orbitrap-HRMS to identify the detectable metabolites in each fraction. We assessed the insulin sensitization activity of each fraction using enzyme-linked immunosorbent assay (ELISA), and then used confocal immunocytochemistry microscopy to measure the translocation of glucose transporter 4 (GLUT4) to the cell membrane. The identified active metabolites were further simulated for its molecular docking interaction using Autodock Tools.

RESULTS

The polar fractions of TCS significantly increased insulin sensitivity, as measured by the inhibition of phosphorylated insulin receptor substrate-1 (pIRS1) at serine-312 residue (ser312) also the increasing number of translocated GLUT4 and glycogen content. We identified 58 metabolites of TCS, including glycosides, flavonoids, alkaloids, coumarins, and nucleotides groups. The metabolomics and molecular docking simulations showed the presence of minor metabolites consisting of tinoscorside D, higenamine, and tinoscorside A as the active compounds.

CONCLUSIONS

Our findings suggest that TCS is a promising new treatment for insulin resistance and the identification of the active metabolites in TCS could lead to the development of new drugs therapies for diabetes that target these pathways.

Isolation of Polyphenols from Aqueous Extract of the Halophyte Salicornia ramosissima

Polyphenols from residual non-food grade Salicornia ramosissima have health-promoting effects in feed, food, or nutraceutical applications. Therefore, the isolation of polyphenols is of interest from a series of environmentally friendly isolation methods with recyclable solvents. The isolation of polyphenols from non-food grade S. ramosissima was investigated using sequential membrane filtration with and without acid pretreatment, liquid-liquid extraction, resin adsorption, and centrifugal partition chromatography (CPC); analyzed by the Folin-Ciocalteu assay for total polyphenols; and finally analyzed using UPLC-TQMS in negative ion-spray mode for detection of 14 polyphenols. Sequential membrane filtration and acid hydrolysis indicated the polyphenols forming complexes with other compounds, retaining the polyphenols in the retentate fraction of large molecular weight cut-off membrane sizes. Conventional liquid-liquid extraction using sequential ethyl acetate and n-butanol showed most polyphenols were extracted, apart from chlorogenic acids, indicating a low isolation efficiency of higher polarity polyphenols. Analysis of the extract after resin adsorption by Amberlite XAD-4 resin showed high efficiency for separation, with 100% of polyphenols adsorbed to the resin after 13 bed volumes and 96.7% eluted from the resin using ethanol. CPC fractionations were performed to fractionate the concentrated extract after resin adsorption. CPC fractionations of the 14 polyphenols were performed using an organic or aqueous phase as a mobile phase. Depending on the mobile phase, different compounds were isolated in a high concentration. Using these easily scalable methods, it was possible to comprehensively study the polyphenols of interest from S. ramosissima and their isolation mechanics. This study will potentially lead the way for the large-scale isolation of polyphenols from S. ramosissima and other complex halophytes. The compounds of the highest concentration after CPC fractionation were isoquercitrin and hyperoside (155.27 mg/g), chlorogenic acid (85.54 mg/g), cryptochlorogenic acid (101.50 mg/g), and protocatechuic acid (398.67 mg/g), and further isolation using CPC could potentially yield novel polyphenol nutraceuticals.

Effective isolation of cannabidiol and cannabidiolic acid free of psychotropic phytocannabinoids from hemp extract by fast centrifugal partition chromatography

Cannabidiol (CBD), together with its precursor cannabidiolic acid (CBDA), is the major phytocannabinoid occurring in most hemp cultivars. To ensure the safe use of these compounds, their effective isolation from hemp extract is required, with special emphasis on the elimination of ∆⁹-tetrahydrocannabinol (∆⁹-THC) and ∆⁹-tetrahydrocannabinolic acid (∆⁹-THCA-A). In this study, we demonstrate the applicability of fast centrifugal partition chromatography (FCPC) as a challenging format of counter-current preparative chromatography for the isolation of CBD and CBDA free of psychotropic compounds that may occur in Cannabis sativa L. plant extracts. Thirty-eight solvent mixtures were tested to identify a suitable two-phase system for this purpose. Based on the measured partition coefficients (K_D) and separation factors (α), the two-phase system consisting of n-heptane:ethyl acetate:ethanol:water (1.5:0.5:1.5:0.5; v:v:v:v) was selected as an optimal solvent mixture. Employing UHPLC-HRMS/MS for target analysis of collected fractions, the elution profiles of 17 most common phytocannabinoids were determined. Under experimental conditions, the purity of isolated CBD and CBDA was 98.9 and 95.1% (w/w), respectively. Neither of ∆⁹-THC nor of ∆⁹-THCA-A were present; only trace amounts of other biologically active compounds contained in hemp extract were detected by screening against in-house spectral library using UHPLC-HRMS.

A Comparison between High-Performance Countercurrent Chromatography and Fast-Centrifugal Partition Chromatography for a One-Step Isolation of Flavonoids from Peanut Hulls Supported by a Conductor like Screening Model for Real Solvents

Peanut hulls (Arachis hypogaea, Leguminosae), which are a side stream of global peanut processing, are rich in bioactive flavonoids such as luteolin, eriodictyol, and 5,7-dihydroxychromone. This study aimed to isolate these flavonoid derivatives by liquid-liquid chromatography with as few steps as possible. To this end, luteolin, eriodictyol and 5,7-dihydroxychromone were isolated from peanut hulls using two different techniques, high-performance countercurrent chromatography (HPCCC) and fast-centrifugal partition chromatography (FCPC). The suitability of the biphasic solvent system composed of n-hexane/ethyl acetate/methanol/water (1.0/1.0/1.0/1.5; v/v/v/v) was determined by the Conductor like Screening Model for Real Solvents (COSMO-RS), which allowed the partition ratio K_D-values of the three main flavonoids to be calculated. After a one-step HPCCC separation of ~1000 mg of an ethanolic peanut hull extract, 15 mg of luteolin and 8 mg of eriodictyol were isolated with purities over 96%. Furthermore, 3 mg of 5,7-dihydroxychromone could be isolated after purification by semi-preparative reversed-phase liquid chromatography (semi-prep. HPLC) in purity of over 99%. The compounds were identified by electrospray ionization mass spectrometry (ESI-MS) and nuclear magnetic resonance spectroscopy (NMR).

Efficient Separation of the Methoxyfuranocoumarins Peucedanin, 8-Methoxypeucedanin, and Bergapten by Centrifugal Partition Chromatography (CPC)

Pure methoxyfuranocoumarins were isolated from a crude petroleum ether extract (CPE; Soxleth extraction efficiency 12.28%) from fruits of Peucedanum tauricum MB. (Apiaceae) by counter-current chromatography in a hydrostatic equilibrium system (centrifugal partition chromatography-CPC). The optimized biphasic solvent system composed of n-heptane-ethyl acetate-methanol-water (5:2:5:2; v/v/v/v) in the ascending mode of elution was used (3 mL/min, 1600 rpm). In the single run, peucedanin (P), 8-methoxypeucedanin (8MP), and bergapten (5MOP) were obtained as pure as 95.6%, 98.1%, and c.a. 100%, respectively. The carefully optimized and developed CPC was effectively transferred from the analytical to the semi-preparative scale (where 20 mg and 150 mg of CPE were loaded, respectively). Identification and quantitative analysis of methoxyfuranocoumarins was carried out in the plant material, in the CPE, and in individual CPC fractions by use of validated high-performance liquid chromatography with diode array detection and mass spectrometry (HPLC-DAD-ESI-MS). For the separation steps, the extraction/isolation recovery was calculated. In this case, CPC proved to be an effective tool for the simultaneous isolation and separation of P, 8MP, and 5MOP from a multicomponent plant matrix, without additional pre-purification steps. The high purity of the obtained plant metabolites makes it possible to consider their use in pharmacological or biological studies.

GUESS - A simple approach to accelerate optimization countercurrent separation

The generally useful estimate of solvent systems (GUESS) method, which is based on thin layer chromatography, is a simple and practical method for selecting solvent systems for countercurrent chromatography (CCC). However, it is rarely used for complex samples derived from natural products. In this study, GUESS was used for CCC solvent system selection and polarity-adjusted CCC separations of several fractions, which were obtained from a silica gel column containing complex compositions with a broad polarity from Salvia bowleyana Dunn. The GUESS method was performed on five fractions based on solvent systems in the n-hexane-ethyl acetate-methanol-water (HEMWat) family. Based on the GUESS results, the optimal solvent systems were selected for CCC separation. Twelve diterpenoids were obtained from the five silica gel column fractions of S. bowleyana Dunn using elution-extrusion countercurrent chromatography (EECCC). These demonstrate that GUESS guidance and the polarity adjustment of the solvent system accelerate the optimization of CCC separation conditions and simplify the process of accommodating a broad polarity of components in complicated mixture fractions. We therefore confirmed the feasibility and advantage of the GUESS method for complex natural chemical component separations.

A convenient separation strategy for fungal anthraquinones by centrifugal partition chromatography

As recently shown, some fungal pigments exhibit significant photoactivity turning them into promising agents for the photodynamic treatment of microbial infections or malignant diseases. In the present study, a separation strategy for fungal anthraquinones was developed based on centrifugal partition chromatography. A suitable method was explored employing a methanolic extract of the fruiting bodies of Cortinarius sanguineus (Agaricales, Basidiomycota). An excellent fractionation was achieved using a biphasic solvent system comprising chloroform/ethyl acetate/methanol/water/acetic acid (3:1:3:2:1, v/v/v/v/v) operating in ascending mode. Experiments on an analytical scale with extracts of closely related Cortinarius species exhibited broad applicability of the devised system. Up to six pigments could be purified directly from the crude extract. Preparative-scale fractionation of the methanol extracts of C. malicorius and C. sanguineus demonstrated that up-scaling was possible without compromising selectivity.

In vitro screening of plant extracts traditionally used as cancer remedies in Ghana - 15-Hydroxyangustilobine A as the active principle in Alstonia boonei leaves

ETHNOPHARMACOLOGICAL RELEVANCE

Cancer represents a major health burden and drain on the global healthcare systems. Traditional African medicine widely use a variety of plant species for treatment of different kinds of cancer. A previous systematic survey by traditional healers in the Ashanti region of Ghana revealed a good overview on the plant species and herbal materials used for the different types of cancer.

AIMS OF THE STUDY

The following study aimed to investigate 18 herbal materials from 10 plant species based on the cancer survey in Ghana regarding potential cytotoxicity against different cancer cell lines under in vitro conditions followed by subsequent bioassay-guided fractionation towards the active principle.

MATERIALS AND METHODS

Ethanol-water (1:1) extracts were tested (1-100 μg/mL) against a panel of cancer cell lines according to their respective traditional use. Selected extracts with relevant cytotoxicity in this screening were also tested against common pediatric malignancies (leukemias (HL-60, REH) and Ewing sarcoma (RD-ES and CADO-ES1)). Bioassay-guided fractionation of the hydroalcoholic extract from Alstonia boonei was performed by liquid-liquid chromatography and preparative HPLC. Preliminary mechanistic studies on the mode of action were performed by flow cytometric cell cycle analysis as well as apoptosis and necrosis staining.

RESULTS

Screening of plant extracts revealed relevant cytotoxicity against all tested cancer cell lines for Alstonia boonei leaves and stem of Paulinia pinnata. The A. boonei extract was additionally found to be active against common pediatric tumor types (leukemias and Ewing sarcoma). Bioassay-guided fractionation of the A. boonei extract revealed the presence of 15-hydroxyangustilobine A 1 as the active principle (IC₅₀ 26 μM against MCF-7 cells). This is the first report of this compound in A. boonei. 1 was shown to lead to cell cycle arrest in the G2/M-phase (MCF-7 cells), triggering cells at least partially into apoptosis.

CONCLUSION

In summary, an appreciable in vitro activity was revealed for the leaf extract from A. boonei and the isolated vallesamine type indole alkaloid 1, which has to be investigated in future studies towards a potential clinical use.

Magnoflorine-Isolation and the Anticancer Potential against NCI-H1299 Lung, MDA-MB-468 Breast, T98G Glioma, and TE671 Rhabdomyosarcoma Cancer Cells

Magnoflorine (MGN) is a quaternary aporphine alkaloid that exhibits numerous therapeutic properties, including neuropsychopharmacological, anti-anxiety, immunomodulatory, anti-inflammatory, antioxidant, or antifungal activities. The aim of the present study was an investigation of the influence of MGN on viability, proliferation, induction of apoptosis, and cell cycle arrest in NCI-H1299 lung, MDA-MB-468 breast, T98G glioma, and TE671 rhabdomyosarcoma cancer cells. MGN was isolated from the roots of Berberis cretica L. by counter-current partition chromatography (CPC). Cell viability and proliferation assessments were performed by means of MTT (3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide) and 5-bromo-2ʹ-deoxyuridine (BrDU) assays, respectively. The induction of apoptosis and cell cycle progression was measured using fluorescence-activated cell sorting analysis. MGN in high doses inhibits proliferation, induces apoptosis, and inhibits cell cycle in S/G2 phases in a dose-dependent manner. MGN seems to be a promising anti-cancer compound in therapy of some types of lung, breast, glioma, and rhabdomyosarcoma cancers, for which current standard therapies are limited or have severe strong side effects.

Correlating the phase settling behavior of aqueous-organic solvent systems in a centrifugal partition chromatograph

The prediction of the performance of a Centrifugal Partition Chromatography (CPC) is a difficult but desirable task. The partitioning of the sample, as well as the fluid dynamical phenomena dispersion, coalescence, and stationary phase retention have to be individually understood. Therefore, the phase settling behavior of different aqueous-organic solvent systems and with this, the dependency of the stationary phase retention in CPC was investigated in this study. On the one hand, batch settling experiments were performed, and the settling velocity of aqueous-organic solvent systems was investigated. With this it was possible to correlate the stationary phase retention in CPC in both operating modes. For descending mode operation a high settling velocity of the lower phase and for ascending mode a high settling velocity of the upper phase is needed for a stable operation and a high stationary phase retention. On the other hand, the dimensionless numbers Capillary number (Ca) and Morton number (Mo) were used to generate a universally applicable correlation for the stationary phase retention in ascending mode. It was shown, that a high stationary phase retention correlates with low values of Ca and Mo, whereas the influence of Mo is neglectable in the parameter space investigated. Within this correlation, the individual influence of each influencing parameter on the stationary phase retention was included. Moreover, this correlation was compared to descriptions for descending mode given in literature. With this it was shown that the minimal stationary phase retention is correlatable to the point of phase inversion.

Characterization and correlation of mobile phase dispersion of aqueous-organic solvent systems in centrifugal partition chromatography

To reach a high separation efficiency using Centrifugal Partition Chromatography (CPC), the fluid dynamical behavior of the liquid-liquid two-phase systems must be clearly understood. The fluid dynamics, namely the dispersion, the coalescence, and the stationary phase retention, have a high impact on a separation. Especially the mobile phase dispersion influences the mass transfer during a separation. In this study, the mobile phase dispersion of different aqueous-organic solvent systems was characterized for ascending and descending mode via video analysis. Thereby the influence of the physical properties of the solvent systems, the operating parameters, and the geometry of the chamber inlet was investigated systematically using dimensional analysis. With the help of the dimensionless numbers Ohnesorge number (Oh_CPC), Eötvös number (Eo_CPC), and Weber number (We_CPC) the impact of the solvent system, the plant parameters, and the operating parameters on the mobile phase dispersion could be described. Inside the three dimensional area, spanned by the dimensionless numbers, each state of mobile phase dispersion (undispersed, low dispersed, highly dispersed, and atomized) could be allocated to an individual region for both operating modes. Moreover, differences in mobile phase deflection depending on the operating mode and a possible reason for these were described.

Additive Analytics: Easy Transformation of Low-Cost Fused Deposition Modeling Three-Dimensional Printers for HPTLC Sample Application

Additive manufacturing, known as three-dimensional (3D) printing technologies, has revolutionized production in all domains of science and technology. Although 3D printing has a high impact on research and development, its capacity to implement low-cost, flexible, and robust sample handling automation has not been exploited in full. To this end, we have created a low-cost, robust, and easy-to-utilize kit to transform an off-the-shelf fused deposition modeling 3D printer to a thin layer chromatography (TLC) sample application device. Our technology solution improves TLC convenience when higher throughput of the established method is required. The developed dual-needle sprayer allows simple and exceptionally robust automatic sample application. The device is especially well-suited for high-performance TLC-assisted method selection in counter-current chromatography. A step-by-step guide and list of required parts, including 3D printable files with instruction, can be obtained from the Supporting Information for research usage and open development.

Isolation and purification of four phenolic glycoside isomers from the leaves of Idesia polycarpa Maxim. by high-speed counter-current chromatography and preparative high-performance liquid chromatography

We established an efficient method using high-speed counter-current chromatography (HSCCC) combined with preparative high-performance liquid chromatography (prep-HPLC) for isolating and purifying phenolic glycoside isomers. The method involves a rapid and sensitive ultra-performance liquid chromatography-under voltage(UPLC-UV) technique using a sub-2 μm core-shell particle column for qualitative and quantitative analysis of four phenolic glycoside isomers from Idesia polycarpa Maxim. leaves. The partially purified samples from ethyl acetate extraction of ethanol extracts of I. polycarpa Maxim. leaves were obtained by HSCCC with a two-phase solvent system composed of n-hexane-ethyl acetate-methanol-water solution (3:5:3:5, v/v/v/v) to obtain fractions I and II, which contain two phenolic glycoside isomers. The two fractions were further isolated by prep-HPLC to yield compounds 1, 2, 3, and 4 with purities of 98.29%, 98.71%, 98.49% and 98.52%, and total recoveries of 93.5%, 72.2%, 75.5% and 88.3%, respectively. Compound 1 was first isolated from I. polycarpa Maxim., while compound 2 was reported to be a new phenolic glycoside, which is 1-[(6'-O-(Z)-p-coumaroyl)-β-D-glucopyranosyl]-oxy-2-phenol. The chemical structures of the four phenolic glycoside isomers were analyzed and confirmed by UPLC, UV, electrospray ionization mass spectrometry (ESI-MS), fourier transform infra-red (FT-IR), 1H-nuclear magnetic resonance (1H NMR), 13C-nuclear magnetic resonance (13C NMR) and 2D nuclear magnetic resonance (2D NMR) spectra. This study opens prospects for broad industrial applications of HSCCC/prep-HPLC for the isolation and purification of isomers.

Classification of biphasic solvent systems according to Abraham descriptors for countercurrent chromatography

The method development of liquid-liquid chromatography, either countercurrent chromatography or centrifugal partition chromatography, is slowed down by the selection of the biphasic solvent system that constitutes its column. This paper introduces a classification of 19 solvent systems, including the most popular systems based on heptane/ethyl acetate/methanol/water, some non-aqueous systems and some greener systems. This classification is based on Abraham descriptors determined through the partition coefficients of 43 probes. Among 21 determined models, nine of them allow an accurate prediction of partition coefficients from solute descriptors and another ten provide a description of the chromatographic interactions at the 5% significance level. A graphical tool (spider diagram) is built for the comparison of the chromatographic columns previously characterized with the solvation parameter model. The position of a solvent system in this spider diagram relates to the interactions at stake, thus the selection of columns offering similar or orthogonal interactions is facilitated, with no previous knowledge of the solute required. This semi-empirical strategy cannot fully predict the retention behavior but can judiciously orientate the user towards a limited number of solvent systems to be experimentally tested.

Methanol linear gradient counter-current chromatography for the separation of natural products: Sinopodophyllum hexandrum as samples

Counter-current chromatography (CCC) is a unique, liquid-liquid partition chromatography process. Both the mobile and stationary phases are liquids, so no solid support matrix is used. CCC has gained wide acceptance as a preparative technique in a variety of fields. Because the mobile and stationary phases are both liquids, gradient elution is difficult to perform with CCC. Phase equilibrium must be maintained, so any change in the composition of one phase may induce a compositional change in the other. In this work, a new linear gradient elution method was developed for CCC. Biphasic solvent systems containing heptane, ethyl acetate, methanol, and water (HepEMWat) in various ratios were prepared and used to optimize both isocratic and linear gradient CCC separation with methanol. We first separated a test mixture of four standard compounds with partition coefficients ranging from 0.8 to 7.8. The separation resembled a reversed-phase process, and elution was performed while progressively decreasing the polarity of the mobile phase. Target molecules with small partition coefficients eluted first in the lower phase of the optimized HepEMWat solvent system. Elution of constituents with large partition coefficients was quite slow under isocratic conditions. Separation time was significantly reduced when elution was performed with a linear gradient using methanol and the optimal HepEMWat system. Elution with a 3:7:4:6 (v/v/v/v) HepEMWat system took approximately 200 min. This included an 80-min isocratic step, followed by gradient elution with methanol from 0% to 30%. The optimized methanol linear gradient CCC method was then used to separate a complex mixture of natural products isolated from Sinopodophyllum hexandrum (Royle) Ying roots. Twelve compounds with a wide range of polarities were well-resolved in a single separation. We have developed a convenient and cost-effective strategy for the separation of complex mixtures. No tedious mobile phase preparation step is required. The volume of unused mobile phase is minimal, so little solvent is wasted. The method is an important advance for the separation of mixtures that contain many compounds with a large range of polarities and partition coefficients, which are common features of natural products.

Superior anticancer activity is demonstrated by total extract of Curcuma longa L. as opposed to individual curcuminoids separated by centrifugal partition chromatography

Three curcuminoids: bisdemethoxycurcumin, demethoxycurcumin, and curcumin from turmeric were successfully separated by a high capacity solvent system composed of heptane: chloroform: methanol: water mixture (5: 6: 3: 2 v/v/v/v) tailored for centrifugal partition chromatographs at K-values of 0.504, 1.057, 1.644, respectively. These three ferulic acid derivatives obtained at a purity rate exceeding 95% were analysed by an HPLC-MS spectrometer. Turmeric extract inhibited the proliferation/viability of A549 human lung cancer, HT29 colon cancer, and T98G glioblastoma cell lines in (3-[4,5-dimethylthiazol-2-yl]-2,5-diphenyltetrazolium bromide) tetrazolium reduction assay (MTT). Single curcuminoids significantly decreased the viability/proliferation of lung cancer cells in a dose-dependent manner. However, total extract displayed the superior anticancer activity in the investigated cell lines. Crude extract in combination with cisplatin augmented the decrease in the viability of cancer cells compared with single compound treatment in A549 lung cancer cells. Total extract of Curcuma longa could be regarded as being more effective against lung cancer cells in vitro than its separated compounds.

The Evaluation of Pro-Cognitive and Antiamnestic Properties of Berberine and Magnoflorine Isolated from Barberry Species by Centrifugal Partition Chromatography (CPC), in Relation to QSAR Modelling

Civilization diseases associated with memory disorders are important health problems occurring due to a prolonged life span. The manuscript shows the results of an in vivo study targeting the emergence of two drug candidates with anti-amnestic properties. The preceding quantitative structure–activity relationship (QSAR) studies provided information on the ability of berberine and magnoflorine to cross the blood–brain barrier (BBB). In the light of these findings, both compounds were purified from crude plant extracts of barberries: berberine—from Berberis siberica using a method published earlier, and magnoflorine—from Berberis cretica by centrifugal partition chromatography (solvent system: ethyl acetate:butanol:water-0.6:1.5:3 v/v/v). Both the compounds were evaluated for their memory enhancing and scopolamine inhibitory properties in an in vivo passive avoidance (PA) test on mice towards short-term and long-term memory. Cognition enhancing properties were observed at the following doses: 5 mg/kg (i.p.) for berberine and 20 mg/kg (i.p.) for magnoflorine. In addition, both the tested isoquinolines with the co-administered scopolamine were found to block long-term but not short-term memory impairment. No influence on the locomotor activity was observed for the tested doses. The results confirmed a marked central activity of magnoflorine and showed the necessity to lower the dosage of berberine. Optimized purification conditions have been elaborated for magnoflorine.

Ionic Liquid-Liquid Chromatography: A New General Purpose Separation Methodology

Ionic liquids can form biphasic solvent systems with many organic solvents and water, and these solvent systems can be used in liquid-liquid separations and countercurrent chromatography. The wide range of ionic liquids that can by synthesised, with specifically tailored properties, represents a new philosophy for the separation of organic, inorganic and bio-based materials. A customised countercurrent chromatograph has been designed and constructed specifically to allow the more viscous character of ionic liquid-based solvent systems to be used in a wide variety of separations (including transition metal salts, arenes, alkenes, alkanes, bio-oils and sugars).

Antiproliferative and Antibacterial Activities of Cirsium scabrum from Tunisia

Several Cirsium species are known for their uses in traditional medicine and consequently are studied for their phytochemical content and their biological activities. In the framework of a previous study conducted on eight extremophile plants from Tunisia, we highlighted that the crude methanolic extract of C. scabrum, a not investigated thistle, showed moderate but quite selective cytotoxic activity against the cancerous cell line J774 compared to the noncancerous cell line WI38 (IC₅₀ = 11.53 μg/ml on J774, IC₅₀ = 29.89 µg/ml on WI38, and selectivity index = 2.6). In the current study, the partitions of the leaves of C. scabrum were analyzed for their antiproliferative activity on the same cell lines. From the most active petroleum ether partition, we isolated four triterpenoids including lupeol, taraxasterol acetate, and a (1 : 1) mixture of 25-hydroperoxycycloart-23-en-3β-ol and 24-hydroperoxycycloart-25-en-3β-ol. These two cycloartane-type triterpenoids are mostly responsible for this cytotoxic activity. On the other hand, the antimicrobial potential of this plant was also evaluated against 36 microorganisms. The moderate antibacterial activity against 6 Staphylococcus aureus and 2 Dermabacter hominis strains is mainly attributed to the butanol partition whose major compounds are glycosides of flavones.

An ecological approach to discover new bioactive extracts and products: the case of extremophile plants

OBJECTIVES

Eight extremophile plants from Tunisia were screened to find natural products with benefits in human health.

METHODS

These plants were collected in different areas in Tunisia. Their methanolic extracts were evaluated for their total phenolic content and for their antiradical (DPPH), antimicrobial (on 35 bacteria and one yeast), antiviral (hepatitis C virus, HCV) and cytotoxic activity (against WI38 and J774 cell lines). The most active species were subjected to a bioguided fractionation.

KEY FINDINGS

The screening revealed promising activity for four plants, but two species have both antiradical and antimicrobial activity: Juncus maritimus and Limonium virgatum. The rhizomes extract of J. maritimus showed the highest activity against HCV, a selective antibacterial activity against Streptococcus dysgalactiae, and a moderate antiradical activity which is due to luteolin isolated in one step by centrifugal partition chromatography. The stems' and leaves' extracts of L. virgatum were rich in polyphenols responsible for the antiradical activity. Also, Limonium extracts showed an antibacterial activity with a broad spectrum.

CONCLUSIONS

Extremophile plants have proven to be a promising source for bioactive metabolites. They have a powerful antioxidant system highly influenced by biotic and abiotic factors and the ability to produce secondary metabolites with antimicrobial activity.

Enhancing silymarin fractionation using the conductor-like screening model for real solvents

A significant hurdle for discovery of plant-derived products is the numerous trial-and-error experiments required to develop an effective purification strategy. To overcome the experimental burden, a quantum mechanics-based molecular modeling approach - known as the COnductor-like Screening Model for Real Solvents (COSMO-RS) - was used to predict a suitable two-phase solvent system to purify six silymarins from an aqueous mixture. Silymarins, a class of flavonolignans found in milk thistle (Silybum marianum L.), are well suited for assessing the use of a molecular modeling approach to predict partitioning in a countercurrent chromatography (CCC) separation because they are well characterized and previous studies report low purity fractionation in liquid-liquid solvent systems. They also present an opportunity to evaluate the use of COSMO-RS in predicting the partitioning of structurally similar isomeric compounds that are present together in an aqueous solution upon extraction from their native source. The COSMO-RS model results predicted the partition coefficients in: three traditional ARIZONA solvent systems (composed of heptane, ethyl acetate, methanol, and water), nine additional variations of this quaternary solvent system, and two chloroform, methanol, and water solvent systems. Predicted results were concise but not accurate when compared to experimental results determined by the shake flask method. The 1:4:3:5 n-heptane:ethyl acetate:methanol:water (v/v/v/v) system was identified to be an improvement on the 1:4:3:4 system previously reported. The present study verified the ability of COSMO-RS to hone in on one or two solvent systems that will yield the best fractionation using CCC.

Sugaring-out strategy for counter-current chromatography isolation: podophyllotoxins and flavones from Dysosma versipellis as examples

In this work, we introduced a sugaring-out strategy for optimizing two-phase solvent systems for counter-current chromatography by adding some sugars into the selected two-phase solvent system.

13C NMR and LC-MS Profiling of Stilbenes from Elicited Grapevine Hairy Root Cultures

Resveratrol and related oligostilbenes are defense molecules produced by grapevine in response to stresses including various elicitors or signal molecules. Together with their prominent role in planta, these compounds have been the center of much attention in recent decades due to their pharmacological properties. The cost-effective production of resveratrol derivatives such as viniferins or more structurally complex stilbene oligomers remains a challenging task. In this study, the chemical diversity of stilbenes produced by Vitis vinifera Pinot Noir hairy roots was investigated after elicitation for 4 days with a mixture of methyl jasmonate (100 μM) and cyclodextrins (50 mM). Two crude extracts obtained from the culture medium and from the hairy roots were fractionated by centrifugal partition chromatography. The fractions were chemically investigated by two complementary identification approaches involving a ¹³C NMR-based dereplication method and liquid chromatography coupled to mass spectrometry (LC-MS). In total, groups of 21 and 18 molecules, including flavonoids and stilbenes, were detected in the culture medium and root extracts, respectively. These included resveratrol monomers, dimers, trimers, and a tetramer, thus highlighting the ability of elicited hairy root culture systems to synthesize a wide diversity of secondary metabolites of pharmaceutical significance. The main compounds were unambiguously identified as trans-resveratrol, ε-viniferin, trans-piceatannol, pallidol, scirpusin A, eriodictyol, naringenin, vitisin B, and maackin.

Effect of operating parameters on a centrifugal partition chromatography separation

Centrifugal partition chromatography (CPC) is the branch of countercurrent chromatography (CCC) that works with single axis hydrostatic columns with rotary seals. The hydrodynamic of the liquid stationary phase-liquid mobile phase equilibrium in the CPC chambers has been studied theoretically and with specially designed CPC columns. In this work, we selected a simple analytical separation (no loading study) of three test solutes, coccine red, coumarin and carvone, with a commonly used heptane/ethyl acetate/methanol/water 1:1:1:1v/v biphasic liquid system and two different rotors: a commercially available 30-mL CPC instrument and a 80-mL prototype rotor designed for productivity. We fully studied this separation in many possible practical operating conditions of the two rotors, aiming at a generic column characterization. The rotor rotation was varied between 1000 and 2800rpm, the aqueous mobile phase flow rate was varied between 1 and 22mL/min with the 30-mL rotor and 10 and 55mL/min with the 80-mL rotor, the upper limits being mechanical constraints and some liquid stationary phase remaining in the rotor. The variations of Sf, the volume ratio of stationary phase in the rotor, were studied versus mobile phase flow rate and rotor rotation speed. A maximum mobile phase linear velocity was found to depend on the centrifugal field for the 30-mL rotor. This maximum velocity was not observed with the 80-mL rotor. Studying the changes in coumarin and carvone peak efficiencies, it is established that the number of cells required to make one theoretical plate, i.e. one chromatographic exchange, is minimized at maximal rotation speed and, to a lesser extent, at high mobile phase flow rate (or linear velocity). Considering the throughput, there is evidence of an optimal flow rate depending on the rotor rotation that is not necessarily the highest possible.

Cancer cell specific cytotoxic effect of Rhoeo discolor extracts and solvent fractions

ETHNOPHARMACOLOGICAL RELEVANCE

Traditional or folk medicine has led to the discovery of important bioactive substances used in several health-related areas. Phytochemicals in Rhoeo discolor (R. discolor) extracts have proven to have important cancer cell specific cytotoxic activity. In the present research, we determined the cytotoxic effect of extracts of R. discolor, a plant commonly used in Mexico for both medicinal and ornamental purposes.

AIM OF THE STUDY

We evaluated the cytotoxic effects against three representative human cancer cell lines: HT-29 colon cancer, Hep-G2 liver cancer and PC-3 prostate cancer cell lines, as well as a control fibroblast cell line NIH 3T3.

MATERIALS AND METHODS

Ten different crude extracts were tested along with fractions derived from the five most bioactive crude extracts. Analytical data, HPLC-MS-TOF, revealed a high content of phenolic compounds such as anthocyanins, ferulic, vanillic, chlorogenic and p-coumaric acid in the extracts. Phenolic compounds have previously been reported as health beneficial with antioxidant and potential cancer specific cytotoxic effects.

RESULTS

Studies revealed that low concentrations of these crude bioactive extracts (10µg/ml) and their fractions (50µg/ml) were effective as cancer specific cytotoxic agents, since they caused a significant proliferation inhibition on cancer cell lines (up to 94.2% in HT-29, 92.9% in Hep-G2 and 61.8% in PC-3 of apoptosis induction) with little harm to the control cell line (no higher than 28.3% apoptosis induction), and, importantly, the most effective extracts were mainly water, methanol and ethanol based.

CONCLUSIONS

These results suggest that a diet containing these compounds may function as a medical aid or chemoprotective.

Fragrant Sesquiterpene Ketones as Trace Constituents in Frankincense Volatile Oil of Boswellia sacra

In a previous study, two highly potent yet unidentified odorants were detected that were present at trace levels in the volatile fraction of Boswellia sacra gum resin. These two compounds were isolated semipreparatively from the volatile oil by a sensory-guided fractionation process involving microscale bulb-to-bulb distillation, countercurrent chromatography, and preparative gas chromatography. In this manner, the two oxygenated sesquiterpenes could be identified as rotundone (1) and mustakone (2). Compound 2 is described for the first time as a potent odorant with a very low odor threshold.

Cylindrofridins A-C, Linear Cylindrocyclophane-Related Alkylresorcinols from the Cyanobacterium Cylindrospermum stagnale

A rapid and exhaustive one-step biomass extraction as well as an enrichment and cleanup procedure has been developed for HPLC-UV detection and quantification of closely related [7.7]paracyclophanes and structural derivatives based on a two-phase solvent system. The procedure has been validated using the biomass of the carbamidocyclophane- and cylindrocyclophane-producing cyanobacterium Nostoc sp. CAVN2 and was utilized to perform a screening comprising 102 cyanobacterial strains. As a result, three new cylindrocyclophane-related alkylresorcinols, cylindrofridins A-C (1-3), and known cylindrocyclophanes (4-6) were detected and isolated from Cylindrospermum stagnale PCC 7417. Structures of 1-3 were elucidated by a combination of 1D and 2D NMR experiments, HRMS, and ECD spectroscopy. Cylindrofridin A (1) is the first naturally occurring [7.7]paracyclophane-related monomeric derivative. In contrast, cylindrofridins B (2) and C (3) represent dimers related to 1. Due to chlorination at the alkyl carbon atom in 1-3, the site of [7.7]paracyclophane macrocycle formation, the cylindrofridins represent linearized congeners of the cylindrocyclophanes. Compounds 1-3 were not toxic against nontumorigenic HaCaT cells (IC50 values >25 μM) compared to the respective cylindrocyclophanes, but 1 was the only cylindrofridin showing moderate activity against methicillin-resistant Staphylococcus aureus (MRSA) and Streptococcus pneumoniae with MIC values of 9 and 17 μM, respectively.

Isolation of Methoxyfuranocoumarins From Ammi majus by Centrifugal Partition Chromatography

Pure methoxyfuranocoumarins were isolated from Ammi majus L. by use of low-pressure column chromatography (LPCC) followed by centrifugal partition chromatography (CPC). The concentrated petroleum ether extract from fruits of A. majus was fractionated on a silica gel column using a gradient of ethyl acetate in dichloromethane (0-80%, v/v). Coumarin-rich fractions were analyzed by thin-layer chromatography (TLC) and high-performance liquid chromatography with diode array detection (HPLC/DAD). Xanthotoxin (8-MOP) and isopimpinellin (isoP), structurally similar compounds, were isolated in one fraction (FR6). To avoid multistep and long-lasting TLC preparation, optimization of CPC conditions has been performed. In one run, an effective separation of 8-MOP and isoP was achieved. The two-phase solvent system composed of n-hexane-ethyl acetate-methanol-water (10 : 8 : 10 : 9; v/v) in an ascending mode (the aqueous phase was a stationary phase, and the organic phase was a mobile phase), with flow rate 3 mL/min and rotation speed 1,600 r.p.m., was used. The identification and high purities of isolated 8-MOP (98.7%) and isoP (100%) were confirmed by HPLC/DAD assay, when compared with standards. The developed CPC method could be applied to the effective isolation of 8-MOP and isoP from plant extracts. The high purity of obtained compounds makes possible further exploitation of these components in biological studies.

Countercurrent Separation of Natural Products: An Update

This work assesses the current instrumentation, method development, and applications in countercurrent chromatography (CCC) and centrifugal partition chromatography (CPC), collectively referred to as countercurrent separation (CCS). The article provides a critical review of the CCS literature from 2007 since our last review (J. Nat. Prod. 2008, 71, 1489-1508), with a special emphasis on the applications of CCS in natural products research. The current state of CCS is reviewed in regard to three continuing topics (instrumentation, solvent system development, theory) and three new topics (optimization of parameters, workflow, bioactivity applications). The goals of this review are to deliver the necessary background with references for an up-to-date perspective of CCS, to point out its potential for the natural product scientist, and thereby to induce new applications in natural product chemistry, metabolome, and drug discovery research involving organisms from terrestrial and marine sources.