Markus Ganzera | University of Innsbruck (original) (raw)

Papers by Markus Ganzera

Planta medica, 2012

The therapy of type-2 diabetes mellitus is one of the major challenges of our age. A possible str... more The therapy of type-2 diabetes mellitus is one of the major challenges of our age. A possible strategy to prevent the progression of this disease is the inhibition of protein tyrosine phosphatase 1B (PTP1B), a major negative regulator in the insulin and leptin signalling pathway. Phellodendri amurensis cortex is a well-known Asian herbal drug traditionally used as antiphlogistic, antibacterial, and anti-inflammatory agent, and its efficacy against diabetes-related symptoms is reported as well. However, information regarding active principle(s) or the molecular mode of action was scarce. By bioguided isolation using an IN VITRO enzyme assay with human recombinant PTP1B, (9 Z)-octadec-9-enoic acid (oleic acid) could be identified as a major PTP1B inhibitor in the bark of Phellodendron amurENSE Rupr. (Rutaceae); it showed an IC₅₀ value of 6.2 µM. Consistent with this inhibition of PTP1B, oleic acid was capable of enhancing insulin signalling in wild-type, but not PTP1B knockout fibrobl...

Phytochemistry, 2001

The C-8-(S) isomer of deoxyloganic acid (7-deoxyloganic acid), together with b-sitosteryl glucosi... more The C-8-(S) isomer of deoxyloganic acid (7-deoxyloganic acid), together with b-sitosteryl glucoside, five known stereoisomeric pentacyclic oxindole alkaloids and the tetracyclic oxindole isorhyncophylline, were isolated from the inner bark of Uncaria tomentosa. Structures of the isolated compounds were based on 1 H and 13 C NMR data, mainly 2D NMR experiments, including 1 H-13 C HMBC and 1 H-1 H NOESY correlation. Furthermore, the hitherto unreported 15 N chemical shifts of the isomeric oxindole alkaloids, using 1 H-15 N HMBC experiments, were utilized to facilitate their characterization. Uncarine D showed weak cytotoxic activity against SK-MEL, KB, BT-549 and SK-OV-3 cell lines with IC 50 values between 30 and 40 mg/ml, while uncarine C exhibited weak cytotoxicity only against ovarian carcinoma (IC 50 at 37 mg/ml). #

Analytica Chimica Acta, 2012

A capillary zone electrophoresis (CZE) method for separation of adenosine and N(6)-isopentenylade... more A capillary zone electrophoresis (CZE) method for separation of adenosine and N(6)-isopentenyladenosine (cytokinin) nucleotides was developed, optimized and validated. Aqueous solutions of several amino acids were evaluated as the background electrolyte constituents. Separation of six nucleotides in less than 20 min with high theoretical plate number (up to 400000 for isopentenyladenosine triphosphate) was achieved using a 100 mM sarcosine/ammonia buffer at pH 10.0. The detection limits of the CZE-UV method are in the low micromolar range (0.69-1.27 μmol L(-1)). Good repeatability of migration times (within 1.3%), peak areas (within 1.8%) and linearity (R(2)>0.999) was achieved over the concentration range 5-1000 μmol L(-1). The method was used to assay the activity of the recombinant Arabidopsis thaliana isopentenyltransferase 1 (AtIPT1). Baseline separation of isopentenylated nucleotides by CE-ESI-MS using a volatile buffer (30 mM ammonium formate; pH 10.0) was accomplished. The identities of the reaction products - isopentenyladenosine di- and triphosphate were confirmed by HPLC-QqTOF-MS. Dephosphorylation of ATP was observed as a parallel reaction.

BMC complementary and alternative medicine, 2014

Lavender remedies have been used in traditional medicine because of antimicrobial, anti-inflammat... more Lavender remedies have been used in traditional medicine because of antimicrobial, anti-inflammatory and mood alleviating effects, but underlying molecular mechanisms are not yet fully elucidated. Recently, studies investigating the effects of lavender oil in the context of psychiatric disorders have indicated potent pharmacological properties. Metabolism of tryptophan by indoleamine 2,3-dioxygenase (IDO) was found to provide a biochemical link between immunology and neuroendocrinology and to be a frequent target of natural products. In this in vitro study, interferences of lavender oil and constituents (-)-linalool, (+)-α-pinene and (+)-limonene with tryptophan catabolism by IDO and formation of neopterin via guanosine triphosphate (GTP)-cyclohydrolase-I and of interferon-γ have been investigated using unstimulated and phytohemagglutinin (PHA)-stimulated human peripheral blood mononuclear cells (PBMC). Treatment with lavender oil dose-dependently suppressed PHA-induced tryptophan b...

Journal of Separation Science, 2011

This manuscript reports on the use of capillary electrochromatography for the determination of ty... more This manuscript reports on the use of capillary electrochromatography for the determination of tyramine, (7) synephrine, and (7) octopamine, the major alkaloids in bitter orange peel. A novel methacrylate-based monolithic stationary phase was prepared by UVphotopolymerization in 100 mm id fused-silica capillaries. It facilitated the quantitative assessment of alkaloids with a mobile phase comprising aqueous 10 mM ammonium acetate in ACN and isopropanol. Applied voltage and temperature were 25 kV and 251C, and samples were injected in electrokinetic mode. The method reported herein revealed adequate sensitivity (LOD r0.6 mg/mL), repeatability (s rel r4.1%), accuracy (recovery rates between 95.2 and 102.2%), and precision (intra-day variation r5.7%, inter-day variation r4.1%). The application of the CEC assay on C. aurantium var. amara plant material and dietary supplements, which usually are advertised for slimming properties, indicated that synephrine (0.17-0.82%) is the dominant alkaloid.

BioMetals, 2011

Despite indications that S. granulatus and S. luteus release iron-chelating compounds, the exact ... more Despite indications that S. granulatus and S. luteus release iron-chelating compounds, the exact spectrum of ferric hydroxamates synthesized by these two Suillus species remained unclear. Hence the aim of this study was to identify all of the main siderophores produced by these two ectomycorrhizal fungal species under pure culture conditions. By means of HPLC and LC-MS analyses we show that S. granulatus releases cyclic and linear fusigen, ferrichrome, coprogen and triacetylfusarinine C into the nutrient medium, while S. luteus culture filtrates contain cyclic and linear fusigen, ferricrocin and coprogen. All of the different siderophores were identified on basis of reference compounds and their specific MS spectra which were recorded on a high resolution MS in positive electrospray ionisation mode. Initial HPLC separations were performed on a C-18 stationary phase, using an acidic eluent (0.1% formic acid in water and acetonitrile) in gradient mode. The potential of these two ectomycorrhizal fungal species to produce siderophores representing three different groups of hydroxamates is discussed in relation to its ecological significance.

Chromatographia, 1997

MECC separation of 11 coumarins has been achieved by use of a running electrolyte at pH 10.4 prep... more MECC separation of 11 coumarins has been achieved by use of a running electrolyte at pH 10.4 prepared from 50 mM boric acid, 10 mM sodium tetraborate and 100 mM sodium hydroxide. The buffer solution contained 50 mM SDS and, as organic modifier, 1% n-propanol. The applied voltage was 25 kV and the temperature of the capillary was kept constant at 20 ~ HPLC baseline separation of the coumarin mixture was obtained by use of a reversed-phase column and an acetonitrile-water solvent gradient. UV detection was performed at 205 nm. Peak assignment and purity control were achieved by HPLC-mass spectrometry with either an electrospray interface or an atmospheric-pressure chemical-ionization interface. Compounds were detected in either negative-or positive-ion modes. These MECC and HPLC-MS methods are suitable for 'fingerprint' analysis of a number of coumarin-containing plants, e.g. Fr. Ammi visnagae, Rd. Scopoliae and Rd. Imperatoriae.

Fitoterapia, 2003

One of the most widely used herbs in Ayurvedic medicine is Ashwaghanda, Withania somnifera, a shr... more One of the most widely used herbs in Ayurvedic medicine is Ashwaghanda, Withania somnifera, a shrub commonly found on the Indian subcontinent. As this plant is increasingly becoming a popular adaptogenic in the western world, analytical methods for its identification and ...

Journal of Pharmaceutical and Biomedical Analysis, 2011

With gaining popularity of herbal remedies worldwide, the need of assuring safety and efficacy of... more With gaining popularity of herbal remedies worldwide, the need of assuring safety and efficacy of these products increases as well. By nature they are complex matrices, comprising a multitude of compounds, which are prone to variation due to environmental factors and manufacturing conditions. Furthermore, many traditional preparations compose of multiple herbs, so that only highly selective, sensitive and versatile analytical techniques will be suitable for quality control purposes. By hyphenating high performance liquid chromatography and mass spectrometry (LC-MS) these high demands are fulfilled, providing the user with a multitude of technical options and applications. This review intends to reflect the impact of LC-MS for medicinal plant analysis focusing on most relevant reports published within the last five years. Commenced by introductory remarks to the different MS approaches most commonly used (e.g. ion trap and time of flight mass analyzers, fragmentation and ionization modes), respective LC-MS applications on the analysis of natural products in medicinal plants, commercial products and biological samples are presented. Methodological aspects like stationary and mobile phase selection or MS settings are discussed, and advantages or limitations of the described techniques are highlighted.

ELECTROPHORESIS, 2008

Herbal preparations, particularly those from traditional Chinese or Indian medicine, are becoming... more Herbal preparations, particularly those from traditional Chinese or Indian medicine, are becoming increasingly popular in Europe and the USA. Their application is often based on long-term historic use rather than on scientific evidences; thus, analytical tools to assure their efficacy, safety and consistency are in great demand. This review evaluates the importance of CE for quality control of herbal medicinal products during the last five years. After briefly describing the general characteristics of natural products analysis by CE, numerous applications on medicinal plants or herbal products are summarized. These examples not only reflect the enormous variability of CE with respect to buffer systems and detection modes employed, but also indicate an increasing importance of this separation technique for quality control purposes compared with more established ones such as HPLC.

Journal of Pharmaceutical and Biomedical Analysis, 2012

Flavonoids are bioactive constituents in Oroxylum indicum seeds, an Asian traditional remedy used... more Flavonoids are bioactive constituents in Oroxylum indicum seeds, an Asian traditional remedy used for the treatment of respiratory infections. In this study the first capillary electrophoretic method for their determination is presented. By using a 25 mM borax buffer at pH 9.2 containing 10 mM SDS as detergent, the determination of seven flavonoids was feasible in only 13 min. Method validation confirmed that the assay is in accordance with ICH requirements in respect to linearity, selectivity, sensitivity, accuracy and precision. Quantitative results revealed that baicalein-7-O-gentiobioside is the most abundant flavonoid in the drug (1.19 to 5.33%), followed by other baicalein derivatives (7-O-glucoside, 7-O-glucuronide). These observations were in good qualitative and quantitative agreement with LC-MS results.

Biomedical Chromatography, 2013

The optical antipodes alkannin/shikonin (A/S) and their esters are potent pharmaceutical substanc... more The optical antipodes alkannin/shikonin (A/S) and their esters are potent pharmaceutical substances found in the roots of 150 Boraginaceous species. This study estimated and compared total and free A/S content and A/S enantiomeric ratio in roots of 11 Alkanna species (A. corcyrensis, A. tinctoria, A. pindicola, A. orientalis, A. methanaea, A. calliensis, A. graeca, A. primuliflora, A. stribrnyi, A. sieberi and A. noneiformis) growing wild in various Greek regions, to compare with cultivated species. It also re-characterized the chirality of A/S commercial samples, since most of them were misnamed by the providers. Several Alkanna species were collected (groups 1 and 3) and botanically identified, whereas some Alkanna species were cultivated from collected seeds (group 2). Free A/S and derivatives were extracted from the dried roots of Alkanna species and analyzed by high performance liquid chromatography-diode array detection (HPLC-DAD). For total A/S content the hexane extracts of Alkanna roots were hydrolyzed and analyzed by HPLC-DAD. Chirality determination and A/S enantiomeric ratio estimation was performed for several commercial samples by polarimetry,chiral LC-DAD and circular dichroism studies. Quantitative analysis revealed that A/S content varied from one region to another even within the same species. Most of the cultivated samples contained greater amounts of free and total A/S compared with the wild ones, wheras no difference was observed in A/S enantiomeric ratio. All the Alkanna samples tested contain mainly alkannin derivatives. Some of the examined Alkanna species of the Greek flora that are endemic to the Mediterranean area could serve as alternative sources for medicinally valuable A/S derivatives. Most of the commercial A/S samples tested were misnamed in terms of chirality and re-characterized.

Journal of Pharmaceutical and Biomedical Analysis, 2010

This manuscript reports on the first analytical procedure for the determination of flavonoids in ... more This manuscript reports on the first analytical procedure for the determination of flavonoids in Celtis australis. The capillary electrophoretic separation of 8 compounds, most of them flavone C-glycosides, was possible using a borax buffer with pH 9.0, which contained 25mM SDS as detergent and 7.5% of n-butanol as organic modifier. Method validation revealed that the developed assay is repeatable (sigma(rel)<or=4.0%), precise (inter-day sigma(rel)<or=6.7%, intra-day sigma(rel)</=3.9%), accurate (recovery rates from 96.8 to 102.3%), sensitive (LOD: 2.2-1.6microg/ml) and linear (R(2)>or=0.9996) within the tested concentration range. The quantitative analysis of several C. australis samples showed that isovitexin is the most abundant representative (0.06-0.09%), at a rather uniform content of total flavonoids of approx. 0.3% in all specimens.

Journal of Agricultural and Food Chemistry, 2015

Blockage of the human ether-à-go-go related gene (hERG) channel can result in life-threatening ve... more Blockage of the human ether-à-go-go related gene (hERG) channel can result in life-threatening ventricular tachyarrhythmia. In an in vitro screening of herbal materials for hERG blockers using an automated two-microelectrode voltage clamp assay on Xenopus oocytes, an alkaloid fraction of Nelumbo nucifera Gaertn. (lotus) leaves induced ∼50% of hERG current inhibition at 100 μg/mL. Chromatographic separation resulted in the isolation and identification of (-)-asimilobine, 1, nuciferine, 2, O-nornuciferine, 3, N-nornuciferine, 4, and liensinine, 5. In agreement with in silico predicted ligand-target interactions, 2, 3, and 4 revealed distinct in vitro hERG blockages measured in HEK293 cells with IC50 values of 2.89, 7.91, and 9.75 μM, respectively. Because lotus leaf dietary weight loss supplements are becoming increasingly popular, the identified hERG-blocking alkaloids were quantitated in five commercially available products. Results showed pronounced differences in the content of hERG-blocking alkaloids ranging up to 992 μg (2) in the daily recommended dose.

Planta medica, Jan 23, 2015

The use of supercritical fluid chromatography for natural product analysis as well as underlying ... more The use of supercritical fluid chromatography for natural product analysis as well as underlying theoretical mechanisms and instrumental requirements are summarized in this review. A short introduction focusing on the historical development of this interesting separation technique is followed by remarks on the current instrumental design, also describing possible detection modes and useable stationary phases. The overview on relevant applications is grouped based on their basic intention, may it be (semi)preparative or purely analytical. They indicate that supercritical fluid chromatography is still primarily considered for the analysis of nonpolar analytes like carotenoids, fatty acids, or terpenes. The low polarity of supercritical carbon dioxide, which is used with modifiers almost exclusively as a mobile phase today, combined with high efficiency and fast separations might explain the popularity of supercritical fluid chromatography for the analysis of these compounds. Yet, it h...

Talanta, Jan 15, 2005

Ephedra sinica (Ma Huang) preparations have recently gained a lot of attention because of serious... more Ephedra sinica (Ma Huang) preparations have recently gained a lot of attention because of serious side effects associated with their prolonged consumption. Citrus aurantium var. amara is now used as an alternative, despite the fact that similar side effects are suspected. We have developed and validated the first analytical procedure for the simultaneous determination of all major alkaloids from both species. Using the ion-pairing reagent SDS, a C-18 stationary phase (3mum material) and a pH-gradient for elution enabled the baseline separation of six alkaloids ((+/-)-octopamine, (+/-)-synephrine, tyramine, (-)-norephedrine, (+)-pseudoephedrine and (-)-ephedrine) within less than 30min. The method is sensitive (LOD</=4.6ng and LOQ</=16.2ng on-column), selective (l-tyrosine and l-phenylalanine, two closely related amino acids did not interfere), accurate (recovery rates of spiked samples were between 97.5 and 102.0%), repeatable (sigma(rel)</=4.6%) and precise (intra-day vari...

Chemical & pharmaceutical bulletin, 2002

Lepidium meyenii (Maca) is one of the few plants that can be cultivated in the harsh climate of t... more Lepidium meyenii (Maca) is one of the few plants that can be cultivated in the harsh climate of the Andes. Its nutritious hypocotyl is traditionally used as food and medicine, and Maca products are increasingly becoming popular in the western world as tonics. This paper describes the first analytical method allowing the determination of the main macamides and macaenes, the marker compounds of L. meyenii. A separation within 35 min was possible by using a C-12 stationary phase, an acidic mobile phase comprising of acetonitrile and water, and raising the column temperature to 40 degrees C. By monitoring the separation at 210 and 280 nm, the markers were detectable as low as 0.40 microg/ml. In order to validate the method, accuracy, precision, linearity, limit of detection and intra/inter day repeatability were determined. The analysis of several commercially available Maca products showed a similar qualitative pattern but significant differences in the quantitative composition. The pe...

The first analytical procedure permitting the analysis of individual bioactive saponins (bacoside... more The first analytical procedure permitting the analysis of individual bioactive saponins (bacosides) in Bacopa monnieri is described. By using 3 m C-8 column material (Luna C-8) and a mobile phase comprising of water and methanol the developed HPLC method enabled the baseline separation of seven major saponins within <30 min. Flow-rate, detection wavelength, and temperature were adjusted to 0.5 ml/min, 205 nm, and 40 • C, respectively. Identity of the analytes was confirmed in an LC-MS experiment, with all compounds being clearly assignable in negative ESI mode. Furthermore, the method was validated for limit of detection, linearity, precision, accuracy inter-day variation. Several B. monnieri samples (extract, plant material, commercial products) were successfully analyzed, each of them containing at least four of the seven reference compounds. Main components were either bacoside A 3 or bacopaside II, least dominant showed to be bacopasides IV and V. The total saponin content in the samples varied from 1.1 to 13.0%.

Planta medica, 2012

The therapy of type-2 diabetes mellitus is one of the major challenges of our age. A possible str... more The therapy of type-2 diabetes mellitus is one of the major challenges of our age. A possible strategy to prevent the progression of this disease is the inhibition of protein tyrosine phosphatase 1B (PTP1B), a major negative regulator in the insulin and leptin signalling pathway. Phellodendri amurensis cortex is a well-known Asian herbal drug traditionally used as antiphlogistic, antibacterial, and anti-inflammatory agent, and its efficacy against diabetes-related symptoms is reported as well. However, information regarding active principle(s) or the molecular mode of action was scarce. By bioguided isolation using an IN VITRO enzyme assay with human recombinant PTP1B, (9 Z)-octadec-9-enoic acid (oleic acid) could be identified as a major PTP1B inhibitor in the bark of Phellodendron amurENSE Rupr. (Rutaceae); it showed an IC₅₀ value of 6.2 µM. Consistent with this inhibition of PTP1B, oleic acid was capable of enhancing insulin signalling in wild-type, but not PTP1B knockout fibrobl...

Phytochemistry, 2001

The C-8-(S) isomer of deoxyloganic acid (7-deoxyloganic acid), together with b-sitosteryl glucosi... more The C-8-(S) isomer of deoxyloganic acid (7-deoxyloganic acid), together with b-sitosteryl glucoside, five known stereoisomeric pentacyclic oxindole alkaloids and the tetracyclic oxindole isorhyncophylline, were isolated from the inner bark of Uncaria tomentosa. Structures of the isolated compounds were based on 1 H and 13 C NMR data, mainly 2D NMR experiments, including 1 H-13 C HMBC and 1 H-1 H NOESY correlation. Furthermore, the hitherto unreported 15 N chemical shifts of the isomeric oxindole alkaloids, using 1 H-15 N HMBC experiments, were utilized to facilitate their characterization. Uncarine D showed weak cytotoxic activity against SK-MEL, KB, BT-549 and SK-OV-3 cell lines with IC 50 values between 30 and 40 mg/ml, while uncarine C exhibited weak cytotoxicity only against ovarian carcinoma (IC 50 at 37 mg/ml). #

Analytica Chimica Acta, 2012

A capillary zone electrophoresis (CZE) method for separation of adenosine and N(6)-isopentenylade... more A capillary zone electrophoresis (CZE) method for separation of adenosine and N(6)-isopentenyladenosine (cytokinin) nucleotides was developed, optimized and validated. Aqueous solutions of several amino acids were evaluated as the background electrolyte constituents. Separation of six nucleotides in less than 20 min with high theoretical plate number (up to 400000 for isopentenyladenosine triphosphate) was achieved using a 100 mM sarcosine/ammonia buffer at pH 10.0. The detection limits of the CZE-UV method are in the low micromolar range (0.69-1.27 μmol L(-1)). Good repeatability of migration times (within 1.3%), peak areas (within 1.8%) and linearity (R(2)&amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;gt;0.999) was achieved over the concentration range 5-1000 μmol L(-1). The method was used to assay the activity of the recombinant Arabidopsis thaliana isopentenyltransferase 1 (AtIPT1). Baseline separation of isopentenylated nucleotides by CE-ESI-MS using a volatile buffer (30 mM ammonium formate; pH 10.0) was accomplished. The identities of the reaction products - isopentenyladenosine di- and triphosphate were confirmed by HPLC-QqTOF-MS. Dephosphorylation of ATP was observed as a parallel reaction.

BMC complementary and alternative medicine, 2014

Lavender remedies have been used in traditional medicine because of antimicrobial, anti-inflammat... more Lavender remedies have been used in traditional medicine because of antimicrobial, anti-inflammatory and mood alleviating effects, but underlying molecular mechanisms are not yet fully elucidated. Recently, studies investigating the effects of lavender oil in the context of psychiatric disorders have indicated potent pharmacological properties. Metabolism of tryptophan by indoleamine 2,3-dioxygenase (IDO) was found to provide a biochemical link between immunology and neuroendocrinology and to be a frequent target of natural products. In this in vitro study, interferences of lavender oil and constituents (-)-linalool, (+)-α-pinene and (+)-limonene with tryptophan catabolism by IDO and formation of neopterin via guanosine triphosphate (GTP)-cyclohydrolase-I and of interferon-γ have been investigated using unstimulated and phytohemagglutinin (PHA)-stimulated human peripheral blood mononuclear cells (PBMC). Treatment with lavender oil dose-dependently suppressed PHA-induced tryptophan b...

Journal of Separation Science, 2011

This manuscript reports on the use of capillary electrochromatography for the determination of ty... more This manuscript reports on the use of capillary electrochromatography for the determination of tyramine, (7) synephrine, and (7) octopamine, the major alkaloids in bitter orange peel. A novel methacrylate-based monolithic stationary phase was prepared by UVphotopolymerization in 100 mm id fused-silica capillaries. It facilitated the quantitative assessment of alkaloids with a mobile phase comprising aqueous 10 mM ammonium acetate in ACN and isopropanol. Applied voltage and temperature were 25 kV and 251C, and samples were injected in electrokinetic mode. The method reported herein revealed adequate sensitivity (LOD r0.6 mg/mL), repeatability (s rel r4.1%), accuracy (recovery rates between 95.2 and 102.2%), and precision (intra-day variation r5.7%, inter-day variation r4.1%). The application of the CEC assay on C. aurantium var. amara plant material and dietary supplements, which usually are advertised for slimming properties, indicated that synephrine (0.17-0.82%) is the dominant alkaloid.

BioMetals, 2011

Despite indications that S. granulatus and S. luteus release iron-chelating compounds, the exact ... more Despite indications that S. granulatus and S. luteus release iron-chelating compounds, the exact spectrum of ferric hydroxamates synthesized by these two Suillus species remained unclear. Hence the aim of this study was to identify all of the main siderophores produced by these two ectomycorrhizal fungal species under pure culture conditions. By means of HPLC and LC-MS analyses we show that S. granulatus releases cyclic and linear fusigen, ferrichrome, coprogen and triacetylfusarinine C into the nutrient medium, while S. luteus culture filtrates contain cyclic and linear fusigen, ferricrocin and coprogen. All of the different siderophores were identified on basis of reference compounds and their specific MS spectra which were recorded on a high resolution MS in positive electrospray ionisation mode. Initial HPLC separations were performed on a C-18 stationary phase, using an acidic eluent (0.1% formic acid in water and acetonitrile) in gradient mode. The potential of these two ectomycorrhizal fungal species to produce siderophores representing three different groups of hydroxamates is discussed in relation to its ecological significance.

Chromatographia, 1997

MECC separation of 11 coumarins has been achieved by use of a running electrolyte at pH 10.4 prep... more MECC separation of 11 coumarins has been achieved by use of a running electrolyte at pH 10.4 prepared from 50 mM boric acid, 10 mM sodium tetraborate and 100 mM sodium hydroxide. The buffer solution contained 50 mM SDS and, as organic modifier, 1% n-propanol. The applied voltage was 25 kV and the temperature of the capillary was kept constant at 20 ~ HPLC baseline separation of the coumarin mixture was obtained by use of a reversed-phase column and an acetonitrile-water solvent gradient. UV detection was performed at 205 nm. Peak assignment and purity control were achieved by HPLC-mass spectrometry with either an electrospray interface or an atmospheric-pressure chemical-ionization interface. Compounds were detected in either negative-or positive-ion modes. These MECC and HPLC-MS methods are suitable for 'fingerprint' analysis of a number of coumarin-containing plants, e.g. Fr. Ammi visnagae, Rd. Scopoliae and Rd. Imperatoriae.

Fitoterapia, 2003

One of the most widely used herbs in Ayurvedic medicine is Ashwaghanda, Withania somnifera, a shr... more One of the most widely used herbs in Ayurvedic medicine is Ashwaghanda, Withania somnifera, a shrub commonly found on the Indian subcontinent. As this plant is increasingly becoming a popular adaptogenic in the western world, analytical methods for its identification and ...

Journal of Pharmaceutical and Biomedical Analysis, 2011

With gaining popularity of herbal remedies worldwide, the need of assuring safety and efficacy of... more With gaining popularity of herbal remedies worldwide, the need of assuring safety and efficacy of these products increases as well. By nature they are complex matrices, comprising a multitude of compounds, which are prone to variation due to environmental factors and manufacturing conditions. Furthermore, many traditional preparations compose of multiple herbs, so that only highly selective, sensitive and versatile analytical techniques will be suitable for quality control purposes. By hyphenating high performance liquid chromatography and mass spectrometry (LC-MS) these high demands are fulfilled, providing the user with a multitude of technical options and applications. This review intends to reflect the impact of LC-MS for medicinal plant analysis focusing on most relevant reports published within the last five years. Commenced by introductory remarks to the different MS approaches most commonly used (e.g. ion trap and time of flight mass analyzers, fragmentation and ionization modes), respective LC-MS applications on the analysis of natural products in medicinal plants, commercial products and biological samples are presented. Methodological aspects like stationary and mobile phase selection or MS settings are discussed, and advantages or limitations of the described techniques are highlighted.

ELECTROPHORESIS, 2008

Herbal preparations, particularly those from traditional Chinese or Indian medicine, are becoming... more Herbal preparations, particularly those from traditional Chinese or Indian medicine, are becoming increasingly popular in Europe and the USA. Their application is often based on long-term historic use rather than on scientific evidences; thus, analytical tools to assure their efficacy, safety and consistency are in great demand. This review evaluates the importance of CE for quality control of herbal medicinal products during the last five years. After briefly describing the general characteristics of natural products analysis by CE, numerous applications on medicinal plants or herbal products are summarized. These examples not only reflect the enormous variability of CE with respect to buffer systems and detection modes employed, but also indicate an increasing importance of this separation technique for quality control purposes compared with more established ones such as HPLC.

Journal of Pharmaceutical and Biomedical Analysis, 2012

Flavonoids are bioactive constituents in Oroxylum indicum seeds, an Asian traditional remedy used... more Flavonoids are bioactive constituents in Oroxylum indicum seeds, an Asian traditional remedy used for the treatment of respiratory infections. In this study the first capillary electrophoretic method for their determination is presented. By using a 25 mM borax buffer at pH 9.2 containing 10 mM SDS as detergent, the determination of seven flavonoids was feasible in only 13 min. Method validation confirmed that the assay is in accordance with ICH requirements in respect to linearity, selectivity, sensitivity, accuracy and precision. Quantitative results revealed that baicalein-7-O-gentiobioside is the most abundant flavonoid in the drug (1.19 to 5.33%), followed by other baicalein derivatives (7-O-glucoside, 7-O-glucuronide). These observations were in good qualitative and quantitative agreement with LC-MS results.

Biomedical Chromatography, 2013

The optical antipodes alkannin/shikonin (A/S) and their esters are potent pharmaceutical substanc... more The optical antipodes alkannin/shikonin (A/S) and their esters are potent pharmaceutical substances found in the roots of 150 Boraginaceous species. This study estimated and compared total and free A/S content and A/S enantiomeric ratio in roots of 11 Alkanna species (A. corcyrensis, A. tinctoria, A. pindicola, A. orientalis, A. methanaea, A. calliensis, A. graeca, A. primuliflora, A. stribrnyi, A. sieberi and A. noneiformis) growing wild in various Greek regions, to compare with cultivated species. It also re-characterized the chirality of A/S commercial samples, since most of them were misnamed by the providers. Several Alkanna species were collected (groups 1 and 3) and botanically identified, whereas some Alkanna species were cultivated from collected seeds (group 2). Free A/S and derivatives were extracted from the dried roots of Alkanna species and analyzed by high performance liquid chromatography-diode array detection (HPLC-DAD). For total A/S content the hexane extracts of Alkanna roots were hydrolyzed and analyzed by HPLC-DAD. Chirality determination and A/S enantiomeric ratio estimation was performed for several commercial samples by polarimetry,chiral LC-DAD and circular dichroism studies. Quantitative analysis revealed that A/S content varied from one region to another even within the same species. Most of the cultivated samples contained greater amounts of free and total A/S compared with the wild ones, wheras no difference was observed in A/S enantiomeric ratio. All the Alkanna samples tested contain mainly alkannin derivatives. Some of the examined Alkanna species of the Greek flora that are endemic to the Mediterranean area could serve as alternative sources for medicinally valuable A/S derivatives. Most of the commercial A/S samples tested were misnamed in terms of chirality and re-characterized.

Journal of Pharmaceutical and Biomedical Analysis, 2010

This manuscript reports on the first analytical procedure for the determination of flavonoids in ... more This manuscript reports on the first analytical procedure for the determination of flavonoids in Celtis australis. The capillary electrophoretic separation of 8 compounds, most of them flavone C-glycosides, was possible using a borax buffer with pH 9.0, which contained 25mM SDS as detergent and 7.5% of n-butanol as organic modifier. Method validation revealed that the developed assay is repeatable (sigma(rel)&amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;lt;or=4.0%), precise (inter-day sigma(rel)&amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;lt;or=6.7%, intra-day sigma(rel)&amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;lt;/=3.9%), accurate (recovery rates from 96.8 to 102.3%), sensitive (LOD: 2.2-1.6microg/ml) and linear (R(2)&amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;gt;or=0.9996) within the tested concentration range. The quantitative analysis of several C. australis samples showed that isovitexin is the most abundant representative (0.06-0.09%), at a rather uniform content of total flavonoids of approx. 0.3% in all specimens.

Journal of Agricultural and Food Chemistry, 2015

Blockage of the human ether-à-go-go related gene (hERG) channel can result in life-threatening ve... more Blockage of the human ether-à-go-go related gene (hERG) channel can result in life-threatening ventricular tachyarrhythmia. In an in vitro screening of herbal materials for hERG blockers using an automated two-microelectrode voltage clamp assay on Xenopus oocytes, an alkaloid fraction of Nelumbo nucifera Gaertn. (lotus) leaves induced ∼50% of hERG current inhibition at 100 μg/mL. Chromatographic separation resulted in the isolation and identification of (-)-asimilobine, 1, nuciferine, 2, O-nornuciferine, 3, N-nornuciferine, 4, and liensinine, 5. In agreement with in silico predicted ligand-target interactions, 2, 3, and 4 revealed distinct in vitro hERG blockages measured in HEK293 cells with IC50 values of 2.89, 7.91, and 9.75 μM, respectively. Because lotus leaf dietary weight loss supplements are becoming increasingly popular, the identified hERG-blocking alkaloids were quantitated in five commercially available products. Results showed pronounced differences in the content of hERG-blocking alkaloids ranging up to 992 μg (2) in the daily recommended dose.

Planta medica, Jan 23, 2015

The use of supercritical fluid chromatography for natural product analysis as well as underlying ... more The use of supercritical fluid chromatography for natural product analysis as well as underlying theoretical mechanisms and instrumental requirements are summarized in this review. A short introduction focusing on the historical development of this interesting separation technique is followed by remarks on the current instrumental design, also describing possible detection modes and useable stationary phases. The overview on relevant applications is grouped based on their basic intention, may it be (semi)preparative or purely analytical. They indicate that supercritical fluid chromatography is still primarily considered for the analysis of nonpolar analytes like carotenoids, fatty acids, or terpenes. The low polarity of supercritical carbon dioxide, which is used with modifiers almost exclusively as a mobile phase today, combined with high efficiency and fast separations might explain the popularity of supercritical fluid chromatography for the analysis of these compounds. Yet, it h...

Talanta, Jan 15, 2005

Ephedra sinica (Ma Huang) preparations have recently gained a lot of attention because of serious... more Ephedra sinica (Ma Huang) preparations have recently gained a lot of attention because of serious side effects associated with their prolonged consumption. Citrus aurantium var. amara is now used as an alternative, despite the fact that similar side effects are suspected. We have developed and validated the first analytical procedure for the simultaneous determination of all major alkaloids from both species. Using the ion-pairing reagent SDS, a C-18 stationary phase (3mum material) and a pH-gradient for elution enabled the baseline separation of six alkaloids ((+/-)-octopamine, (+/-)-synephrine, tyramine, (-)-norephedrine, (+)-pseudoephedrine and (-)-ephedrine) within less than 30min. The method is sensitive (LOD</=4.6ng and LOQ</=16.2ng on-column), selective (l-tyrosine and l-phenylalanine, two closely related amino acids did not interfere), accurate (recovery rates of spiked samples were between 97.5 and 102.0%), repeatable (sigma(rel)</=4.6%) and precise (intra-day vari...

Chemical & pharmaceutical bulletin, 2002

Lepidium meyenii (Maca) is one of the few plants that can be cultivated in the harsh climate of t... more Lepidium meyenii (Maca) is one of the few plants that can be cultivated in the harsh climate of the Andes. Its nutritious hypocotyl is traditionally used as food and medicine, and Maca products are increasingly becoming popular in the western world as tonics. This paper describes the first analytical method allowing the determination of the main macamides and macaenes, the marker compounds of L. meyenii. A separation within 35 min was possible by using a C-12 stationary phase, an acidic mobile phase comprising of acetonitrile and water, and raising the column temperature to 40 degrees C. By monitoring the separation at 210 and 280 nm, the markers were detectable as low as 0.40 microg/ml. In order to validate the method, accuracy, precision, linearity, limit of detection and intra/inter day repeatability were determined. The analysis of several commercially available Maca products showed a similar qualitative pattern but significant differences in the quantitative composition. The pe...

The first analytical procedure permitting the analysis of individual bioactive saponins (bacoside... more The first analytical procedure permitting the analysis of individual bioactive saponins (bacosides) in Bacopa monnieri is described. By using 3 m C-8 column material (Luna C-8) and a mobile phase comprising of water and methanol the developed HPLC method enabled the baseline separation of seven major saponins within <30 min. Flow-rate, detection wavelength, and temperature were adjusted to 0.5 ml/min, 205 nm, and 40 • C, respectively. Identity of the analytes was confirmed in an LC-MS experiment, with all compounds being clearly assignable in negative ESI mode. Furthermore, the method was validated for limit of detection, linearity, precision, accuracy inter-day variation. Several B. monnieri samples (extract, plant material, commercial products) were successfully analyzed, each of them containing at least four of the seven reference compounds. Main components were either bacoside A 3 or bacopaside II, least dominant showed to be bacopasides IV and V. The total saponin content in the samples varied from 1.1 to 13.0%.