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Medicinal plants grown under stress conditions reveal higher concentrations of relevant specialized metabolites than well-watered plants, putatively due to an enhanced biosynthesis. Yet, stress also reduced the biomass gain. Accordingly, the concentration increase in comparison to control plants could also be due to lesser biomass employed as the reference value, whereas the rate of biosynthesis may remain unchanged. For an unequivocal proof that stress indeed enhances the biosynthesis, the total amount of the substances per plant has to be determined. In this study, we investigated the stress-induced impact on the alkaloids accumulated in Catharanthus roseus and quantified both, the changes in concentration and in the entire amount of alkaloids. At any time, all Catharanthus roseus plants grown under drought stress exhibited a markedly higher alkaloid concentration compared to the well-watered controls. However, by calculating the entire alkaloid content per plant, a corresponding increment occurred only within the first two weeks of drought stress. Thereafter, no significant differences among drought treatments and control were detected. Finally, within the last week, the alkaloid content per plant decreased markedly, although there was a meaningfully higher concentration of alkaloids in the drought-stressed plants. In contrast, when plants had been exposed to high salt concentrations, the alkaloid concentrations were quite the same in stressed and control plants. The related total contents were significantly lower in plants exposed to salt stress. These results display that both phenomena, an increased rate of biosynthesis and lesser reference values, i.e., the biomass, contribute to the stress-related increase in the concentration of natural product. Moreover, it has to be considered that the enhancement of biosynthesis could be due to either an "active" up-regulation of biosynthetic capacity or a "passive" shift caused by the over-reduced status as a result of the stress-induced stomatal closure., (Copyright © 2021 Elsevier Ltd. All rights reserved.)

Nectandra leucantha (Lauraceae) is a tree indigenous to the tropical Atlantic forests of Brazil, one of the most biodiverse flora hotspots worldwide. This plant species contains high concentrations of neolignan and dehydrodieugenol derivatives that express significant in-vitro activities against various parasite strains. These activities are however responsible for severe tropical human infections, such as Leishmaniasis (Leishmania spp.) and Chagas disease (Trypanosoma cruzi), which have been classified by the World Health Organization (WHO) as Neglected Tropical Diseases (NTDs). In order to optimize the isolation process for these target metabolites, n-hexane extract of the leaves was separated by means of semi-preparative high performance countercurrent chromatography (HPCCC) and scale-up spiral-coil countercurrent chromatography (sp-CCC) systems. Several biphasic solvent mixtures were evaluated for their partitioning effects on neolignans, resulting in the selection of an optimized system n-hexane - ethylacetate - methanol - water (7:3:7:3, v/v/v/v). The chromatographic experiments on the HPCCC and sp-CCC were run in the head-to-tail mode with 500 mg and 16 g injections, respectively. For specific and multiple metabolite detection, the recovered CCC-fractions were off-line injected, in the sequence of recovery, to an electrospray mass-spectrometry (ESI-MS/MS) device. A projection of the single ion traces of the target compounds, in the positive ionization mode at a scan range of m/z 100-1500, located chromatographic areas where the co-elution effects occurred and pure target metabolites were present. Five major target neolignans were specifically detected, which enabled the accurate pooling of CCC-fractions for an optimum recovery of the metabolites. The direct comparison of the performance characteristics of the two CCC-devices, with very different mechanical designs was achieved by the conversion of the time axis into a partition ratio (K D ) separation scale. As a result, the compound specific K D -elution values of the target neolignan were determined in high precision, while the comparison of the calculated separation factor (α) and resolution factor (R S ) values revealed a superior separation performance for the HPCCC system. Also, the reproducibility of detected metabolites in the two CCC experiments was confirmed by small variations (ΔK D  ±0.1). Neolignan target compounds with anti-parasite activities were successfully isolated in the 100 mg to 4 g range in a single lab-scale countercurrent chromatographic process step., (Copyright © 2019. Published by Elsevier B.V.)

Electrospray mass spectrometry-profiling guided the metabolome investigation of a C18 reversed phase adsorbate of Opuntia stricta var. dillenii fruits following analytical, and semi-preparative high-performance countercurrent chromatography (HPCCC) fractionation, and visualization of molecular weight elution profiles based on selected single ion-traces. Experimental partition-ratio values K D , and peak widths for detected metabolites were determined. Structural characterization of metabolites, and co-elution effects were monitored in the scan range m/z 150-2200. The polar ion-pair activated solvent system tert.-butylmethylether - n-butanol - acetonitrile - water (0.7% trifluoroacetic acid) [2:2:1:5]) was used for partition-ratio K D improvement of ionic betalains. HPCCC operations were in the head-to-tail mode using the elution-extrusion approach. Selected ESI-MS ion traces visualized the elution of fourty-three metabolites, whereas twenty-one were identified as known betalain pigments, and their classic degradation products, and chlorinated betacyanin artefacts. Potentially, novel fruit metabolites of Opuntia were recognized by unknown molecular weights, and MS/MS fragmentations. Off-line ESI-MS fraction monitoring determined peak elution windows, and resulted in K D -based chromatographic scales. Detectable metabolites were compared by separation- α, and resolution-factors R S revealing a better performance of the analytical HPCCC experiment. Experimental metabolite K D -values from analytical and semi-preparative HPCCC runs were widely consistent, and confirmed the reproducibility of the technique based on the used sample material., (Copyright © 2019. Published by Elsevier B.V.)

Porcelia macrocarpa (Warm.) R. E. Fries (Annonaceae) is an endemic plant in Brazil where its tasty pulp has been eaten fresh. The hexane extract from its flowers was subjected to chromatographic procedures to afford four acetylene derivatives identified as octadec-9-ynoic (stearolic acid - 1), (11E)-octadec-11-en-9-ynoic (santalbic acid - 2), 8-hydroxyoctadec-9,11-diynoic (3) and 8-hydroxyoctadec-17-en-9,11-diynoic (isanolic acid - 4) acids by NMR and HRESIMS. Among tested compounds against trypomastigote forms of T. cruzi, octadec-9-ynoic acid (1) displayed higher potential with IC 50  = 27.6 µM and a selectivity index (SI) higher than 7. Compounds 2 and 3 showed IC 50 of approximately 60 µM while compound 4 was inactive. The lethal action of the compound 1 was investigated using spectrofluorometric techniques to detect ROS content, plasma membrane permeability and plasma membrane potential by flow cytometry. Compound 1 showed no alteration in the production of ROS of treated trypomastigotes and no alteration of the plasma membrane permeability was observed as detected by the fluorescent probe SYTOX-green after 120 min of incubation. However, by using the potential-sensitive fluorescent probe DiSBAC 2 (3), compound 1 caused depolarization of the plasma membrane potential when compared to untreated parasites. Our results demonstrated the anti-T. cruzi effects of compounds 1-3 isolated from flowers of P. macrocarpa and indicated that the lethal effect of compound 1 in T. cruzi could be associated to the plasma membrane disturbance of the parasite., (Copyright © 2018 Elsevier Inc. All rights reserved.)

Chagas disease is a neglected tropical disease, caused by the protozoan parasite Trypanosoma cruzi, which affects more than eight million people in Tropical and Subtropical countries especially in Latin America. Current treatment is limited to nifurtimox and benznidazole, both with reduced effectiveness and high toxicity. In this work, the n-hexane extract from leaves of Nectandra leucantha (Lauraceae) displayed in vitro antitrypanosomal activity against T. cruzi. Using several chromatographic steps, four related neolignans were isolated and chemically characterized as dehydrodieugenol B (1), 1-(8-propenyl)-3-[3'-methoxy-1'-(8-propenyl)-phenoxy]-4,5-dimethoxybenzene (2), 1-[(7S)-hydroxy-8-propenyl]-3-[3'-methoxy-1'-(8'-propenyl)-phenoxy]-4-hydroxy-5-methoxybenzene (3), and 1-[(7S)-hydroxy-8-propenyl]-3-[3'-methoxy-1'-(8'-propenyl)-phenoxy]-4,5-dimethoxybenzene (4). These compounds were tested against intracellular amastigotes and extracellular trypomastigotes of T. cruzi and for mammalian cytotoxicity. Neolignan 4 showed the higher selectivity index (SI) against trypomastigotes (>5) and amastigotes (>13) of T. cruzi. The investigation of the mechanism of action demonstrated that neolignan 4 caused substantial alteration of the plasma membrane permeability, together with mitochondrial dysfunctions in trypomastigote forms. In silico studies of pharmacokinetics and toxicity (ADMET) properties predicted that all compounds were non-mutagenic, non-carcinogenic, non-genotoxic, weak hERG blockers, with acceptable volume of distribution (1.66-3.32 L/kg), and low rodent oral toxicity (LD 50 810-2200 mg/kg). Considering some clinical events of cerebral Chagas disease, the compounds also demonstrated favorable properties, such as blood-brain barrier penetration. Unfavorable properties were also predicted as high promiscuity for P450 isoforms, high plasma protein binding affinity (>91%), and moderate-to-low oral bioavailability. Finally, none of the isolated neolignans was predicted as interference compounds (PAINS). Considering the promising chemical and biological properties of the isolated neolignans, these compounds could be used as starting points to develop new lead compounds for Chagas disease., (Copyright © 2017 Elsevier B.V. All rights reserved.)

Countercurrent chromatography (CCC) is being widely used across the world for purification of various materials, especially in natural product research. The predictability of CCC scale-up has been successfully demonstrated using specially designed instruments of the same manufacturer. The reality is that the most of CCC users do not have access to such instruments and do not have enough experience to transfer methods from one CCC column to another. This unique study of three international teams is based on innovative approach to simplify the scale-up between different CCC machines using fractionation of Schinus terebinthifolius berries dichloromethane extract as a case study. The optimized separation methodology, recently developed by the authors (Part I), was repeatedly performed on CCC columns of different design available at most research laboratories across the world. Hexane - ethyl acetate - methanol - water (6:1:6:1, v/v/v/v) was used as solvent system with masticadienonic and 3β-masticadienolic acids as target compounds to monitor stationary phase retention and calculate peak resolution. It has been demonstrated that volumetric, linear and length scale-up transfer factors based on column characteristics can be directly applied to different i.d., volume and length columns independently on instrument make in an intra-apparatus scale-up and inter-apparatus method transfer., (Copyright © 2016 Elsevier B.V. All rights reserved.)

Equisetum palustre L. is known for its toxicity for livestock. Several studies in the past addressed the isolation and identification of the responsible alkaloids. So far, palustrine (1) and N(5)-formylpalustrine (2) are known alkaloids of E. palustre. A HPLC-ESI-MS/MS method in combination with simple sample work-up was developed to identify and quantitate Equisetum alkaloids. Besides the two known alkaloids six related alkaloids were detected in different Equisetum samples. The structure of the alkaloid palustridiene (3) was derived by comprehensive 1D and 2D NMR experiments. N(5)-Acetylpalustrine (4) was also thoroughly characterized by NMR for the first time. The structure of N(5)-formylpalustridiene (5) is proposed based on mass spectrometry results. Twenty-two E. palustre samples were screened by a HPLC-ESI-MS/MS method after development of a simple sample work-up and in most cases the set of all eight alkaloids were detected in all parts of the plant. A high variability of the alkaloid content and distribution was found depending on plant organ, plant origin and season ranging from 88 to 597mg/kg dried weight. However, palustrine (1) and the alkaloid palustridiene (3) always represented the main alkaloids. For the first time, a comprehensive identification, quantitation and distribution of Equisetum alkaloids was achieved., (Copyright © 2015 Elsevier Ltd. All rights reserved.)

'Countercurrent chromatography' (CCC) is an ideal technique for the recovery, purification and isolation of bioactive natural products, due to the liquid nature of the stationary phase, process predictability and the possibility of scale-up from analytical to preparative scale. In this work, a method developed for the fractionation of Schinus terebinthifolius Raddi berries dichloromethane extract was thoroughly optimized to achieve maximal throughput with minimal solvent and time consumption per gram of processed crude extract, using analytical, semi-preparative and preparative 'high performance countercurrent chromatography' (HPCCC) instruments. The method using the biphasic solvent system composed of n-heptane-ethyl acetate-methanol-water (6:1:6:1, v/v/v/v) was volumetrically scaled up to increase sample throughput up to 120 times, while maintaining separation efficiency and time. As a fast and specific detection alternative, the fractions collected from the CCC-separations were injected to an 'atmospheric pressure chemical ionization mass-spectrometer' (APCI-MS/MS) and reconstituted molecular weight MS-chromatograms of the APCI-ionizable compounds from S. terebinthifolius were obtained. This procedure led to the direct isolation of tirucallane type triterpenes such as masticadienonic and 3β-masticadienolic acids. Also oleanonic and moronic acids have been identified for the first time in the species. In summary, this approach can be used for other CCC scale-up processes, enabling MS-target-guided isolation procedures., (Copyright © 2015 Elsevier B.V. All rights reserved.)

For the development of an efficient two-stage isolation process for high-speed countercurrent chromatography (HSCCC) with focus on principal metabolites from the ethyl acetate extract of the halophyte plant Salicornia gaudichaudiana, separation selectivities of two different biphasic solvent systems with similar polarities were evaluated using the elution and extrusion approach. Efficiency in isolation of target compounds is determined by the solvent system selectivity and their chronological use in multiple separation steps. The system n-hexane-ethyl acetate-methanol-water (0.5:6:0.5:6, v/v/v/v) resulted in a comprehensive separation of polyphenolic glycosides. The system n-hexane-n-butanol-water (1:1:2, v/v/v) was less universal but was highly efficient in the fractionation of positional isomers such as di-substituted cinnamic acid quinic acid derivatives. Multiple metabolite detection performed on recovered HSCCC tube fractions was done with rapid mass-spectrometry profiling by sequential off-line injections to electrospray mass-spectrometry (ESI-MS/MS). Selective ion traces of metabolites delivered reconstituted preparative HSCCC runs. Molecular weight distribution of target compounds in single HSCCC tube fractions and MS/MS fragment data were available. Chromatographic areas with strong co-elution effects and fractions of pure recoverable compounds were visualized. In total 11 metabolites have been identified and monitored. Result of this approach was a fast isolation protocol for S. gaudichaudiana metabolites using two solvent systems in a strategic sequence. The process could easily be scaled-up to larger lab-scale or industrial recovery., (Copyright © 2015 Elsevier B.V. All rights reserved.)

Propolis is a glue material collected by honeybees which is used to seal cracks in beehives and to protect the bee population from infections. Propolis resins have a long history in medicinal use as a natural remedy. The multiple biological properties are related to variations in their chemical compositions. Geographical settings and availability of plant sources are important factors for the occurrence of specific natural products in propolis. A propolis ethylacetate extract (800mg) from Saudi Arabia (Al-Baha region) was separated by preparative scale high-speed countercurrent chromatography (HSCCC) using a non-aqueous solvent system n-hexane-ACN (1:1, v/v). For multiple metabolite detection, the resulting HSCCC-fractions were sequentially injected off-line into an atmospheric pressure chemical ionization mass-spectrometry (APCI-MS/MS) device, and a reconstituted mass spectrometry profile of the preparative run was visualized by selected ion traces. Best ion-intensities for detected compounds were obtained in the negative APCI mode and monitored occurring co-elution effects. HSCCC and successive purification steps resulted in the isolation and characterization of various bioactive natural products such as (12E)- and (12Z)-communic acid, sandaracopimaric acid, (+)-ferruginol, (+)-totarol, and 3β-acetoxy-19(29)-taraxasten-20a-ol using EI-, APCI-MS and 1D/2D-NMR. Cycloartenol-derivatives and triterpene acetates were isolated in mixtures and elucidated by EI-MS and 1D-NMR. Free fatty acids, and two labdane fatty acid esters were identified by APCI-MS/MS. In total 19 metabolites have been identified. The novel combination of HSCCC fractionation, and APCI-MS-target-guided molecular mass profiling improve efficiency of lead-structure identification., (Copyright © 2014 Elsevier B.V. All rights reserved.)

Betacyanins, red-violet plant pigments, were fractionated by ion-pair high-speed countercurrent chromatography (IP-HSCCC) from leaves extract of Iresine lindenii Van Houtte, an ornamental plant of the family Amaranthaceae. An HSCCC solvent system consisting of TBME-1-BuOH-ACN-H2O (1:3:1:5, v/v/v/v) was applied using ion-pair forming heptafluorobutyric acid (HFBA). Significantly different elution profiles of betacyanin diastereomeric pairs (derivatives based on betanidin and isobetanidin) observed in the HSCCC in comparison to HPLC systems indicate a complementarity of both techniques' fractionation capabilities. The numerous diastereomeric pairs can be selectively separated from each other using the HSCCC system simplifying the pigment purification process. Apart from the three well known highly abundant pigments (amaranthine, betanin and iresinin I) together with their isoforms, three new acylated (feruloylated and sinapoylated) betacyanins as well as known pigment hylocerenin (previously isolated from cacti fruits) were characterized in the plant for the first time and they are new for the whole Amaranthaceae family., (Copyright © 2014 Elsevier B.V. All rights reserved.)

Saponaria officinalis L. (Caryophyllaceae), also known as fuller's herb or soapwort is a medicinal plant, which grows from Europe to Central Asia. Medicinal properties attributed to this plant include its antitussive and galactogogue properties. Recently, bisdesmodic saponins with very specific structural features from S. officinalis have been shown to strongly enhance the efficacy of specific targeted toxins (anti-tumor antibodies connected to protein toxins) in-vitro and in-vivo in a synergistic manner. In the presently reported novel approach we used preparative all-liquid high-speed countercurrent chromatography (HSCCC) to recover a total of 22 fractions using biphasic solvent system tert-butylmethylether/n-butanol/acetonitrile/water 1:3:1:5 (v/v/v/v) from a complex precipitated crude saponin mixture. Out of these 22 fractions, 3 fractions had the enhancer effect on anti-tumor toxins out of which one fraction (F7) was further tested elaborately in different cell lines. The molecular weight distribution and compound profiles of separated saponins were monitored by off-line injections of the sequentially collected fractions to an electrospray ion-trap mass-spectrometry system (ESI-IT-MS). The functional saponin fractions were mainly bisdesmosidc and contained saponin m/z 1861 amongst other. Using the bio-assay guided monitoring, the highly active fractions containing 2 to 3 bisdesmodic saponins (5μg/mL) were screened for their effectiveness in enhancing the anti-tumor activity of targeted toxin Sap3-EGF, which was determined using the impedance based real-time cell cytotoxicity evaluation. This novel combination of HSCCC fractionation, MS-target-guided profiling procedure and bio-assay guided fractionation yielded 100mg of functional saponins from a 60g crude drug powder in a rapid and convenient manner., (Copyright © 2014 Elsevier B.V. All rights reserved.)

In this study, preparative ion-pair high-speed countercurrent chromatography was directly coupled to an electrospray ionization mass-spectrometry device (IP-HSCCC/ESI-MS-MS) for target-guided fractionation of high molecular weight acyl-oligosaccharide linked betacyanins from purple bracts of Bougainvillea glabra (Nyctaginaceae). The direct identification of six principal acyl-oligosaccharide linked betacyanins in the mass range between m/z 859 and m/z 1359 was achieved by positive ESI-MS ionization and gave access to the genuine pigment profile already during the proceeding of the preparative separation. Inclusively, all MS/MS-fragmentation data were provided during the chromatographic run for a complete analysis of substitution pattern. On-line purity evaluation of the recovered fractions is of high value in target-guided screening procedures and for immediate decisions about suitable fractions used for further structural analysis. The applied preparative hyphenation was shown to be a versatile screening method for on-line monitoring of countercurrent chromatographic separations of polar crude pigment extracts and also traced some minor concentrated compounds. For the separation of 760mg crude pigment extract the biphasic solvent system tert.-butylmethylether/n-butanol/acetonitrile/water 2:2:1:5 (v/v/v/v) was used with addition of ion-pair forming reagent trifluoroacetic acid. The preparative HSCCC-eluate had to be modified by post-column addition of a make-up solvent stream containing formic acid to reduce ion-suppression caused by trifluoroacetic acid and later significantly maximized response of ESI-MS/MS detection of target substances. A variable low-pressure split-unit guided a micro-eluate to the ESI-MS-interface for sensitive and direct on-line detection, and the major volume of the effluent stream was directed to the fraction collector for preparative sample recovery. The applied make-up solvent mixture significantly improved smoothness of the continuously measured IP-HSCCC-ESI-MS base peak ion trace in the experimental range of m/z 50-2200 by masking stationary phase bleeding and generating a stable single solvent phase for ESI-MS/MS detection. Immediate structural data were retrieved throughout the countercurrent chromatography run containing complete MS/MS-fragmentation pattern of the separated acyl-substituted betanidin oligoglycosides. Single ion monitoring indicated clearly the base-line separation of higher concentrated acylated betacyanin components., (Copyright 2010 Elsevier B.V. All rights reserved.)

The natural pigment composition of purple bracts of Bougainvillea glabra (Nyctaginaceae) consists of a highly complex mixture of betacyanins solely differing by the substitution with a variety of acyl-oligoglycoside units. This study was focused on a two-dimensional chromatography approach, a combination of preparative high-speed countercurrent chromatography (HSCCC) and analytical C18-HPLC with ESI-DAD-MS/MS detection which finally enabled a more detailed view into the pigment profile and elucidated the existence of an overwhelming amount of varying betacyanin structures occurring in Bougainvillea bracts. The detected molecular weights of the pigments reached so far unknown high values and ranged up to maximum values of 1653 and 1683 Da for the largest molecules due to oligosaccharide linkage and multiple acyl substitutions. The preparative IP-HSCCC separation yielded 15 complex fractions containing betacyanins of enhanced polarity as well as structures with highly increased lipophilicity. Betacyanin structures extended by large oligosaccharide chains with bigger number of glycoside units and also carrying a reduced number of hydroxycinnamic acid substitutions were characteristic for polar pigments occurring mainly in the early eluting CCC fractions. IP-HSCCC was proven to be extremely effective for fractionating this complex crude betalain pigment extract into more defined 'polarity-windows'. Structural analysis by analytical LC-ESI-MS/MS in the positive ionization mode detected a total sum of 146 different betacyanin pigments in the CCC fractions of reduced complexity., (Copyright 2010 Elsevier B.V. All rights reserved.)

Polar betacyanin pigments together with betaxanthins from ripe cactus fruits of Hylocereus polyrhizus (Cactaceae) were fractionated by means of preparative ion-pair high-speed countercurrent chromatography (IP-HSCCC) also using the elution-extrusion (EE) approach for a complete pigment recovery. HSCCC separations were operated in the classical 'head-to-tail' mode with an aqueous mobile phase. Different CCC solvent systems were evaluated in respect of influence and effectiveness of fractionation capabilities to separate the occurring pigment profile of H. polyrhizus. For that reason, the additions of two different volatile ion-pair forming perfluorinated carboxylic acids (PFCA) were investigated. For a direct comparison, five samples of Hylocereus pigment extract were run on preparative scale (900 mg) in 1-butanol-acetonitrile-aqueous TFA 0.7% (5:1:6, v/v/v) and the modified systems tert.-butyl methyl ether-1-butanol-acetonitrile-aqueous PFCA (2:2:1:5, v/v/v/v) using 0.7% and 1.0% trifluoroacetic acid (TFA) or heptafluorobutyric acid (HFBA) in the aqueous phase, respectively. The chemical affinity to the organic stationary CCC solvent phases and in consequence the retention of these highly polar betalain pigments was significantly increased by the use of the more lipophilic fluorinated ion-pair reagent HFBA instead of TFA. The HFBA additions separated more effectively the typical cacti pigments phyllocactin and hylocerenin from betanin as well as their iso-forms. Unfortunately, similar K(D) ratios and selectivity factors alpha around 1.0-1.1 in all tested solvent systems proved that the corresponding diastereomers, 15S-type pigments cannot be resolved from the 15R-epimers (iso-forms). Surprisingly, additions of the stronger ion-pair reagent (HFBA) resulted in a partial separation of hylocerenin from phyllocactin which were not resolved in the other solvent systems. The pigments were detected by means of HPLC-DAD and HPLC-electrospray ionization-MS using also authentic reference materials.

Isomangiferin was isolated from Cyclopia subternata using a multi-step process including extraction, liquid-liquid partitioning, high-speed counter-current chromatography (HSCCC) and semi-preparative reversed-phase high-performance liquid chromatography (HPLC). Enrichment of phenolic compounds in a methanol extract of C. subternata leaves was conducted using liquid-liquid partitioning with ethyl acetate-methanol-water (1:1:2, v/v). The enriched fraction was further fractionated using HSCCC with a ternary solvent system consisting of tert-butyl methyl ether-n-butanol-acetonitrile-water (3:1:1:5, v/v). Isomangiferin was isolated by semi-preparative reversed-phase HPLC from a fraction containing mostly mangiferin and isomangiferin. The chemical structure of isomangiferin was confirmed by LC-high-resolution electrospray ionization MS, as well as one- and two-dimensional NMR spectroscopy.

The first preparative fractionation of betalain pigments by means of ion-pair high-speed counter-current chromatography (IP-HSCCC) from berry extracts of Phytolacca americana (Phytolaccaceae) is presented. A novel HSCCC solvent system consisting of 1-butanol-acetonitrile-water (5:1:6, v/v/v) was applied using ion-pair forming trifluoroacetic acid at low concentration (0.7%, v/v). Affinity of polar betacyanins and betaxanthins to the organic stationary phase of the biphasic HSCCC solvent mixture was considerably improved. Partitioning coefficient values and influence of increasing trifluoroacetic acid additions to the biphasic solvent mixture were measured for all identified betacyanins and betaxanthins. Gentle separation by IP-HSCCC of the injected pigment extract (900 mg) yielded sufficient amounts of the principal pigments 15S-betanin/15R-isobetanin. The pure epimers separated by C18-HPLC were immediately studied by one- and two-dimensional NMR. In the recovered fractions, minor concentrated betacyanins and betaxanthins were significantly enriched by IP-HSCCC and were detected for the first time in the extracts of P. americana. IP-HSCCC and C18-HPLC were shown to be complementary techniques in the isolation procedure of recovering minor concentrated, highly polar and chemically instable betacyanins and betaxanthin from complex plant matrices. Altogether, identification of 17 betalains was achieved by HPLC-diode array detection-electrospray ionization MS/MS in the HSCCC fractions with their respective isomers, also resulting in the tentative elucidation of betacyanins with novel salicylic acid substitution pattern in the berry extracts of P. americana.

This study presents the novel direct coupling of preparative high-speed counter-current chromatography with electrospray ionization mass spectrometry (HSCCC/ESI-MS-MS) for continuous MS data acquisition, and 'target'-guided fractionation of polyphenolic compounds from sea buckthorn juice concentrate (Hippophaë rhamnoides L. ssp. rhamnoides, Elaeagnaceae). It was demonstrated that a combination of HSCCC and ESI-MS-MS is a versatile tool for fast screening and sensitive detection of bioactive natural products in crude extracts. Sample fractionation will be simplified by knowing the continuous MS data of the complete HSCCC separation. Already during the separation, immediate structural information of the separated compounds is provided. Peak purity of HSCCC is assessable by complete ion traces and fractions can directly be evaporated for further one-/two-dimensional NMR analysis.

Phytochemical investigation of root and stem-bark of the West African medicinal plant Ongokea gore resulted in the isolation of four novel flavonoids with an unusual cyclohexyl substituent instead of the common aromatic ring B. The structures of the isolated compounds were elucidated by spectroscopic methods, mainly 1D and 2D NMR, and subsequently, the structures were corroborated by chemical conversion to (-)-(S)-sakuranetin. The absolute configurations, and preferred conformations were determined by NOE experiments and CD measurements.

Purification of astilbin from the rhizome extract of Smilax glabra was conducted using a high-speed counter-current chromatograph equipped with a 700 mL column. In a single operation, 1.5 g of crude sample was separated to yield 105 mg of component astilbin and 48 mg of isoastilbin while the upper phase of the two-phase solvent system composed of n-hexane-n-butanol-water (1:1:2, v/v/v) was used for stationary phase. The chemical structures of the two flavonoid glycosides were confirmed by electrospray ionization ion trap multiple mass spectrometry and nuclear magnetic resonance experiments.

Salicin in the bark extract of Salix alba and amygdalin in the fruit extract of Semen armeniacae were each separated by slow rotary counter-current chromatography (SRCCC). The apparatus was equipped with a 40-L column made of 17 mm i.d. convoluted Teflon tubing. A 500g amount of crude extract containing salicin at 13.5% was separated yielding 63.5 g of salicin at 95.3% purity in 20h using methyl tert-butyl ether-l-butanol (1:3) saturated by methanol-water (1:5) as a stationary phase and methanol-water (1:5) saturated by methyl tert-butyl ether-1-butanol (1:3) as a mobile phase. A 400g amount of crude extract containing amygdalin at 55.3% was isolated to yield 221.2g of amygdalin at 94.1% purity in 19h using ethyl acetate-1-butanol (1:2) saturated by water as a stationary phase and water saturated by ethyl acetate-1-butanol (1:2) as a mobile phase. The flow rate of the mobile phase was 50 ml/min. The results show that industrial SRCCC separation of salicin and amygdalin is feasible using a larger column at a higher flow rate of the mobile phase.

High-speed counter-current chromatography (HSCCC) was used for the separation of anthocyanins on a preparative scale from bilberry fruit crude extract (Vaccinium myrtillus, Ericaceae) with a biphasic solvent system composed of methyl tert-butyl ether-n-butanol-acetonitrile-water-trifluoroacetic acid (1:4:1:5:0.01, v/v). Each injection of 500 mg crude extract yielded 130 mg of pure delphinidin-3-O-sambubioside, and 77 mg of pure cyanidin-3-O-sambubioside. The two anthocyanin disaccharides with a glucose (2 --> 1) xylose unit are novel compounds for bilberry fruit, and were elucidated by means of electrospray ionization MS-MS, 1H, 13C, distortion less enhancement by polarization transfer NMR, and two-dimensional HC-correlation experiments (heteronuclear multiple bond correlation and heteronuclear multiple quantum correlation).

Preparative separation of flavonoid glycosides in leaves extract of Ampelopsis grossedentata was conducted using high-speed counter-current chromatograph (HSCCC) with a solvent system composed of n-hexane-ethyl acetate-methanol-water (1:6:1.5:7.5, v/v). In a single operation, 28 mg of 5,7-dihydroxy-3',4'-trihydroxyflavone-3-O-6''-rhamnose and 18 mg of 5,7-dihydroxy-3',4'-dihydroxyflavone-3-O-6''-rhamnose was obtained from 150 mg of the extract. The chemical structure of the two compounds was elucidated by electrospray ionization (EIS) MS and NMR.

Phytochemical investigation of avocado seed material (Persea americana Mill., Lauraceae) resulted in the isolation of two glucosylated abscisic acid derivates. One of these was not known as a natural product and can be regarded as a potential 'missing link' in abscisic acid metabolism in plants. After fractionation by high-speed countercurrent chromatography, and multiple steps of column chromatography, structures were elucidated by 1D-, 2D-NMR, electrospray-MS to be the novel beta-d-glucoside of (1'S,6'R)-8'-hydroxyabscisic acid, and (1'R,3'R,5'R,8'S)-epi-dihydrophaseic acid beta-d-glucoside. Absolute configuration was determined by circulardichroism, optical rotation, and by NOE experiments.

The Chinese phytomedicinal formulation Sanqi Zongdai Pian, traditionally prepared from crude extracts from roots of Panax notoginseng (Araliaceae), contains highly polar dammarane saponins which were separated at a preparative scale using high-speed counter-current chromatography (HSCCC). In each operation, 283 mg methanolic extract of five tablets was separated and yielded pure 157, 17, 13 and 56 mg of ginsenoside-Rb1, notoginsenoside-R1, ginsenoside-Re and ginsenoside-Rg1, respectively, n-hexane-n-butanol-water (3:4:7, v/v/v) was used for the two-phase solvent system of the HSCCC separation. The chemical structures of three ginsenosides and one notoginsenoside were elaborated by means of electrospray ionization MS-MS and NMR analysis.

The bioactive diterpenes andrographolide and neoandrographolide from the leaves of Andrographis paniculata NEES (Acanthaceae) were successfully separated by counter-current chromatography. A single 280-min separation yielded 189 mg of 99.9% andrographolide and 9.5 mg of 98.5% neoandrographolide applying water-methanol-ethyl acetate-n-hexane (2.5:2.5:4:1) solvent system. Structure confirmation was done by electrospray MS, one-dimensional NMR experiments, circular dichroism, optical rotation dispersion, and specific optical rotation [alpha]D.