Preparative Medium-pressure Liquid Research Articles

Isolation, Formulation, and Efficacy Enhancement of Morin Emulsified Carriers Against Lung Toxicity in Rats.

The present study demonstrates a preparative medium-pressure liquid chromatography (MPLC) method for isolation of Morin besides evaluating its efficacy in comparison with its self-nanoemulsifying drug delivery (SNEDD) and nanoemulsion (NE) systems against in-vivo HgCl2-induced lung toxicity in rats. Morin was isolated from hydroalcoholic (70%) extract of Psidium guajava leaves by MPLC. The purity (> 90%) was done using HPLC. Screening of Morin solubility was studied to identify the components of each system. The prepared formulae were assessed for their thermodynamic stability, rheological properties, emulsification time, size, zeta potential beside its dissolution. The selected formulae according to the smallest size, highest zeta potential, and release at Q10min were assessed for their morphology by transmission electron microscopy (TEM) and protective potential against in-vivo HgCl2-induced lung toxicity in rats. All formulae were stable with Newtonian flow, emulsification time was (< 134 ± 10s), size (< 40nm) with zeta potential (> - 10.36 ± 0.99mV). The extent of free Morin dissolved from capsule showed significantly the lowest percent released (22.21 ± 1.45%) while in case of SNEDDs and NEs (> 55% dissolved). The morphology of the selected Morin formulae showed spherical shape within the nano-range. Supplementation of Morin and its formulae to rats caused significant decrease in C-reactive protein, hepatoglobin, hydroproxide, lung nitric oxide, tumor necrosis factor-α, immunoglobulin (E and G), histamine, malondialdehyde, and interleukin-6 gene expression while significant increase in immunoglobulin A, caspase-3, catalase, and glutathione peroxidase compared to HgCl2. SNEDD and NE formulae could ameliorate lung toxicity in a mechanism related to their antioxidant and anti-inflammatory potential.

Targeted Isolation of Indolopyridoquinazoline Alkaloids from Conchocarpus fontanesianus Based on Molecular Networks.

A dichloromethane-soluble fraction of the stem bark of Conchocarpus fontanesianus showed antifungal activity against Candida albicans in a bioautography assay. Off-line high-pressure liquid chromatography activity-based profiling of this extract enabled a precise localization of the compounds responsible for the antifungal activity that were isolated and identified as the known compounds flindersine (17) and 8-methoxyflindersine (18). As well as the identification of the bioactive principles, the ultra-high-pressure liquid chromatography-high-resolution mass spectrometry metabolite profiling of the dichloromethane stem bark fraction allowed the detection of more than 1000 components. Some of these could be assigned putatively to secondary metabolites previously isolated from the family Rutaceae. Generation of a molecular network based on MS(2) spectra indicated the presence of indolopyridoquinazoline alkaloids and related scaffolds. Efficient targeted isolation of these compounds was performed by geometric transfer of the analytical high-pressure liquid chromatography profiling conditions to preparative medium-pressure liquid chromatography. This yielded six new indolopyridoquinazoline alkaloids (5, 16, 19-22) that were assigned structurally. The medium-pressure liquid chromatography separations afforded additionally 16 other compounds. This work has demonstrated the usefulness of molecular networks to target the isolation of new natural products and the value of this approach for dereplication. A detailed analysis of the constituents of the stem bark of C. fontanesianus was conducted.

Enrichment and identification of cyclized hopanoids from Shengli lignite

Fourteen cyclized hopanoids, including hydrobenzohopanes, benzohopanes, and rearranged benzohopanes, were enriched from Shengli lignite via fractional extraction and preparative medium-pressure liquid chromatography. Their structures were tentatively identified by gas chromatography/mass spectrometry. Rearranged benzohopanes, which were unreported before, are probably produced from the corresponding benzohopanes via methyl rearrangement reaction.

RECOVERY OF BIOACTIVE PHENOLIC COMPOUNDS FROM OLIVE MILL WASTE WATER, POMEGRANATE PEEL, AND EUROPEAN CRANBERRYBUSH (VIBURNUM OPULUS L.) JUICE BY PREPARATIVE MPLC

□ In this study, preparative medium pressure liquid chromatography (MPLC) was used for the purification of some phenolic compounds including hydroxytyrosol, chlorogenic acid, and punicalagin from olive mill waste water (OMWW), European cranberrybush (Viburnum opulus L.) juice, and pomegranate peel, respectively. While the polyphenols of OMWW and European cranberrybush juice were extracted with ethyl acetate (EtOAc), methanol was used for pomegranate peel extraction. At the end of the extraction process, the solvents were removed by rotary evaporator and the residue passed into the water phase. After the centrifugation and microfiltration procedure, the injection of samples was carried out by MPLC. The outflow of the colon was collected at specific periods and the predetermined polyphenols for purification were identified with High-Pressure Liquid Chromatography with UV Detector (HPLC-UV). After the collection of defined fractions, chlorogenic acid, and punicalagin were concentrated with a rotary evaporator and transformed into particle form by freeze drying. Hydroxytyrosol was produced as concentrated liquid by using a rotary evaporator. The purities of the obtained compounds were determined as 90.2%for hydroxytyrosol, 92.5%for chlorogenic acid, and 97.1%for punicalagin. Moreover, the inhibition percentages of these compounds on 2,2-diphenyl-1-picrylhydrazyl (DPPH) were established, respectively, as 76.01, 84.90, and 94.64.

Chemical Composition of the Bark of Tetrapterys mucronata and Identification of Acetylcholinesterase Inhibitory Constituents

The secondary metabolite content of Tetrapterys mucronata, a poorly studied plant that is used occasionally in Brazil for the preparation of a psychotropic plant decoction called "Ayahuasca", was determined to establish its chemical composition and to search for acetylcholinesterase (AChE) inhibitors. The ethanolic extract of the bark of T. mucronata exhibited in vitro AChE inhibition in a TLC bioautography assay. To localize the active compounds, biological profiling for AChE inhibition was performed using at-line HPLC-microfractionation in 96-well plates and subsequent AChE inhibition bioautography. The analytical HPLC-PDA conditions were transferred geometrically to a preparative medium-pressure liquid chromatography column using chromatographic calculations for the efficient isolation of the active compounds at the milligram scale. Twenty-two compounds were isolated, of which six are new natural products. The structures of the new compounds (9, 10, 16-18, and 20) were elucidated by spectroscopic data interpretation. Compounds 1, 5, 6, 9, and 10 inhibited AChE with IC50 values below 15 μM.

Phytochemical Analysis of an Exotic Brasilian Fruit, Spondias tuberosa, Using 2D MPLC X UHPLC/TOF/MS Monitoring

The Northeast Region of Brazil is a place known for its great variety of edible fruits, some of them being endemic, and used as food by the local population. In most cases, these fruits have only been poorly studied for their chemical constituents and biological activities. The biological screening of several fruit extracts led to the chemical investigation of the methanolic pulp extract of Umbú (Spondias tuberosa, Anacardiaceae) followed by the analysis of cancer chemopreventive and acetylcholinesterase activities. The extract presented high antioxidant activities in the DPPH (89%), ABTS (97%) and ORAC (64%) assays at 40 µg mL-1, as well as 61% inhibition of acetylcholinesterase activity at the same concentration. The analytical HPLC-UV conditions were geometrically transferred to a preparative medium pressure liquid chromatography (MPLC-UV) by chromatographic calculations. All of the 250 MPLC fractions were monitored by UHPLC/TOF/MS. Six compounds were isolated for the first time in this plant in a single step. The structures of the isolated compounds were elucidated by classical spectroscopic methods including 2D NMR and HR-MS. Such type of studies may lead to the development of functional foods with valuable health benefits.

Antistaphylococcal activity of Inula helenium L. root essential oil: eudesmane sesquiterpene lactones induce cell membrane damage

The purpose of this study was to investigate the inhibitory/bactericidal activity and cell membrane effects of the hydrodistilled essential oil of Inula helenium L. roots against Staphylococcus aureus. Additionally, detailed chemical investigation was done in order to pinpoint the most active oil constituents and also the parts of these molecules responsible for their antimicrobial effect. The minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) were determined using the broth microdilution method. The membrane-active nature of this oil was investigated by measuring the culture turbidity, leakage of phosphates, and 260-nm-absorbing material, together with lysis of the exposed cells. Finally, the effect of the oil on the cells was visualized using scanning electron microscopy (SEM). The chemical composition of the essential oil was analyzed using gas chromatography-mass spectrometry (GC-MS) and preparative medium-pressure liquid chromatography (MPLC). Chemical modification of the oil was performed using catalytic hydrogenation (H(2), Pd/C) and reduction with NaBH(4). The MIC and MBC values were 0.01 μl mL(-1) and 0.02 μl mL(-1), respectively. Membrane damage was demonstrated through increased permeability (phosphates and nucleic acid leakage), followed by lysis of the exposed cells, captured on SEM images. The most active constituents were alantolactone, isoalantolactone, and diplophyllin. The essential oil showed very potent antistaphylococcal activity, with obvious membrane-damaging effects. Sesquiterpene lactones were found to be the most active principles of the oil, whose eudesmane core olefinic bonds, along with the α,β-methylene-lactone ring, are essential structural parts responsible for the exhibited antimicrobial activity.

Reassessing the melatonin pharmacophore—Enantiomeric resolution, pharmacological activity, structure analysis, and molecular modeling of a constrained chiral melatonin analogue

3-(Acetylaminomethyl)-2-(ethoxycarbonyl)-6-methoxy-1,3,4,5-tetrahydrobenzo[ cd]indole ( 2) is a rigid melatonin analogue that as a racemate displays about the same affinity and intrinsic activity of melatonin ( 1) in in vitro experiments. We report here the resolution of the racemate by preparative medium pressure liquid chromatography (MPLC) and the X-ray determination of the R absolute configuration of the (−)-enantiomer. The two enantiomers were separately tested as MT 1 and MT 2 ligands, and the (+)-( S)- 2 showed a potency comparable to that of melatonin and about three orders of magnitude greater than that of its enantiomer. The information obtained by crystallographic analysis and NMR studies about the conformational preference for 2 and by the pharmacological characterization of ( R)- 2 and ( S)- 2 was employed in a molecular modeling study, aimed at reassessing the melatonin receptor pharmacophore model for agonist compounds. Chiral enantioselective agonists reported in the literature were also included in the study.

97/03614 Benzene recovery: a plant preserving ecology and saving resources

Fourteen cyclized hopanoids, including hydrobenzohopanes, benzohopanes, and rearranged benzohopanes, were enriched from Shengli lignite via fractional extraction and preparative medium-pressure liquid chromatography. Their structures were tentatively identified by gas chromatography/mass spectrometry. Rearranged benzohopanes, which were unreported before, are probably produced from the corresponding benzohopanes via methyl rearrangement reaction.

Synthese, Struktur und Reaktionen Phenylethinyl‐substituierter Bicyclo[3.3.0]octane

Syntheses, Structures, and Reactions of Phenylethynyl-Substituted Bicyclo[3.3.0]octanes[1] The bicyclo[3.3.0]octane-3,7-dione 5 adds phenylethynyl-cerium(III) dichloride to afford an almost quantitative yield of the 3,7-diols exo,exo-, exo,endo-, and endo,endo-6 (1:2:2) which are separated by flash chromatography. While both exo,endo- and endo,endo-6 are dehydrated by sulfuric acid in acetic acid to furnish the isomeric dienes C2- and Cs-7, exo,exo-6 rearranges to a bicyclic ketone (8), two tricyclic ketones (10a, b), and a tetracyclic ketone (12) as a consequence of the proximity of the endo-phenylethynyl groups. The rearrangements of exo,exo-6 are avoided when chlorotrimethylsilane is used as the dehydrating agent. Thus, a 90% yield of C2- and Cs-7 is realized from the mixture of the 3,7-diols 6. – The 2,6-dione 13 reacts with phenylethynylcerium(III) dichloride to yield the hydroxyketone endo-14 and the 2,6-diols exo,endo- and endo,endo-16 (1:1:3) which are separated by cyclic medium-pressure liquid chromatography. Dehydration of endo-14 furnishes the enone 15 which adds phenylethynylcerium(III) dichloride to afford the endo alcohol 17. Eventually, this is dehydrated to the diene 18. Formation of 18 from exo,endo-16, and endo,endo-16 as well, is accompanied by dehydrating cyclization to the oxanortwistane 19 (20%) readily separated from 18 by chromatography. – The encumbered diphenyldione 20 is converted into the highly substituted bicyclo[3.3.0]octa-2,6-diene 24 in 68% overall yield in a four-step sequence involving additions of phenylethinyl-cerium(III) dichloride (20→21 and 22→23) followed by dehydration of the endo alcohols 21 (→22) and 23 (→24). – In contrast to 20, the dicyanodiketone 25 adds phenylethynylcerium(III) dichloride at both carbonyl groups and, surprisingly, from the endo face, thus affording the exo,exo-diol 26. At 150°C, 26 undergoes quantitatively an intramolecular dehydro Diels-Alder reaction to yield the 1-phenylnaphthalene derivative. 30. The lack of incorporation of deuterium from deuterated solvents attests to the intramolecular nature of the 1,5-hydrogen shift converting the intermediate six-membered cyclic cumulene 29 to the final product 30. – Dehydration of 26 produces the highly substituted bicyclo[3.3.0]octadiene-2,6-dicarbonitrile 27 which rearranges into an equilibrium mixture of the diastereomeric bisallenes exo,exo-, exo,endo-, and endo,endo-28 on treatment with a strong base. In the same way, the identical mixture of diastereomers is obtained from each of the bisallenes 28 which had been separated by preparative medium-pressure liquid chromatography. – The gross structures of all new compounds are based on spectroscopic evidence including IR, NMR, and mass spectra. The structures of endo,endo-6, 12, exo-14, endo,endo-16 (α- and β-form), 19, 24, 26 · 2 Me2SO, 27, exo,exo-28, and endo,endo-28 are established by X-ray diffraction analyses. The preferred conformations of exo-14, endo,endo-16 (α- and β-form), and 26 · 2 Me2SO in the crystalline state, as well as the stereochemistry of the nucleophilic attack to bicyclo[3.3.0]octanediones, and the mechanisms of the intramolecular reactions between the phenylethynyl groups are discussed.

Strategies of mobile phase transfer from thin-layer to medium-pressure liquid chromatography with silica is the stationary phase

The location of the fronts in thin-layer chromatography (TLC) with multicomponent mobile phases is discussed with reference to the possibilities of mobile phase transfer via analytical overpressured-layer chromatography (OPLC) to preparative medium-pressure liquid chromatography (MPLC). The advantage of this procedure is that the mobile phase of the TLC separation where the substance zones are distributed over the whole R F range can be transferred to preparative column chromatography without limitations. Because OPLC may be used as equilibrated or non-equilibrated planar column systems and all mobile-phase fronts may be seen, it can be applied as a pilot method for preparative MPLC. Depending on the results of the analytical OPLC separation, four possibilities exist for mobile phase transfer to MPLC; these are discussed. The generally useful method is to equilibrate the dry-filled column (silica of TLC quality with an average particle size of 15 μm) with a solvent in which the substances to be separated do not migrate and which was used for the prerun in analytical OPLC. The separation is then started with the optimized TLC mobile phase where the substances are distributed over the whole R F range. Transfer of the optimized TLC mobile phase via OPLC to MPLC is demonstrated by the separation of furocoumarin isomers from the roots of Heracleum sphondylium and the ginsenosides from Panax ginseng C. A. Meyer. The separation of anthraquinone aglycones from Rhamnus frangula is an example of the direct transfer of the mobile phase from TLC to MPLC.

Preparative medium pressure liquid chromatographic (MPLC) and semipreparative HPLC separation of furocoumarin isomers

Preparative medium pressure liquid chromatography and semi-preparative high performance liquid chromatography on silica were employed for the isolation of eight furocoumarin isomers (iso-bergapten, angelicin, psoralen, bergapten, pimpinellin, sphondin, xanthotoxin and isopimpinellin). The conditions were transposed from analytical on-line overpressured layer chromatography and analytical high performance liquid chromatography, respectively. The retention data of the analytical on-line overpressured layer chromatographic separation and the preparative medium pressure liquid chromatographic isolation show a linear relationship. Using 15 μm TLC silica 60 as stationary phase a dry-packing procedure aas developed for labomatic medium pressure liquid chromatographic glass columns. The efficiency of the preparative separation techniques was demonstrated by the isolation of the investigated furocoumarins from Heraclei mantegazziani radix and from Pimpinellae radix (Balkan quality).

Strategy for the analysis of steryl esters from plant and animal tissues

Methods are described for the analysis of intact steryl esters present in complex mixtures isolated from plant or animal tissues. A preliminary examination by analytical thin-layer chromatography (TLC) and capillary column gas chromatography—mass spectrometry (GCMS) under electron impact (EI) ionisation reveals the complexity of the mixture and the nature of the steryl moieties. Preparative TLC is then utilised to separate the steryl esters into two broad groups, containing fatty acyl moieties of shorter (C 2C 8) or longer chain length (C 10C 22). The shorter-chain fatty acyl steryl esters are separated by adsorption high-performance liquid chromatography (HPLC) on a LiChrosorb Silica-60 column. The steryl esters with longer-chain fatty acyl moieties are analysed by reversed-phase HPLC on either an Ultrasphere ODS, 5-μm, or a S3 Spherisorb ODS, 3-μm, column. Steryl esters with unsaturated fatty acyl moieties are eluted with the shorter-chain fatty acyl steryl esters. The presence of the unsaturated fatty acyl esters can be monitored by analytical argentation TLC, which will also reveal the degree of unsaturation. The steryl esters are fractionated into the saturated, mono-, di-, tri- and polyene acyl types by preparative medium-pressure liquid chromatography on a column of 10% AgNO 3-silica gel. Each of these steryl ester types can then be resubmitted to reversed-phase HPLC or analysed by GCMS on a short fused-silica capillary column with abonded phase of the OV-1 type. GCMS on a magnetic-sector instrument under negative-ion chemical ionisation conditions with ammonia as the reagent gas produces fragment ions for both the steryl and fatty acyl moieties, thus permitting identification of the individual intact steryl esters. These various methods are illustrated by analyses of the steryl ester mixtures obtained from human plasma, barley seedlings, palm oil and rape seed oil.

Präparative mitteldruck-flüssigkeitschromatographie

An efficient preparative medium-pressure liquid chromatography system is described. The unit offers rapid and economic separation of lipophilic compounds on preparative glass columns filled with silica gel by a tamping method. Details for the construction of the chromatograph unit and its operation are given and various types of components such as pumps, pulse dampers, columns, detectors and fraction collectors are discussed.

Preparative High-Performance Liquid Chromatography Isolation of the True Proazulenes from Artemisia Arborescens L

Abstract The use of the preparative medium-pressure liquid chromatography (prep-MPLC) and the preparative high-pressure liquid chromatography (prep-HPLC) techniques for the separation of the main true proazulenes from a purified extract of Artemisia arborescens L. are reported and discussed.

Separation of diastereomers using a low cost preparative medium-pressure liquid chromatograph

ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTSeparation of diastereomers using a low cost preparative medium-pressure liquid chromatographA. I. Meyers, Joel Slade, R. Keith Smith, and E. D. MihelichCite this: J. Org. Chem. 1979, 44, 13, 2247–2249Publication Date (Print):June 1, 1979Publication History Published online1 May 2002Published inissue 1 June 1979https://doi.org/10.1021/jo01327a045RIGHTS & PERMISSIONSArticle Views377Altmetric-Citations47LEARN ABOUT THESE METRICSArticle Views are the COUNTER-compliant sum of full text article downloads since November 2008 (both PDF and HTML) across all institutions and individuals. These metrics are regularly updated to reflect usage leading up to the last few days.Citations are the number of other articles citing this article, calculated by Crossref and updated daily. Find more information about Crossref citation counts.The Altmetric Attention Score is a quantitative measure of the attention that a research article has received online. Clicking on the donut icon will load a page at altmetric.com with additional details about the score and the social media presence for the given article. Find more information on the Altmetric Attention Score and how the score is calculated. Share Add toView InAdd Full Text with ReferenceAdd Description ExportRISCitationCitation and abstractCitation and referencesMore Options Share onFacebookTwitterWechatLinked InReddit PDF (368 KB) Get e-AlertsSupporting Info (1)»Supporting Information Supporting Information Get e-Alerts