Differential cytotoxic properties of Helleborus niger L. on tumour and immunocompetent cells.

ETHNOPHARMACOLOGICAL RELEVANCE: In Romanian folk medicine, Helleborus niger L. is used for the treatment of rheumatoid arthritis or viral infections and in complementary therapy, especially in anthroposophic medicine (AM), where the plant is administered as an adjuvant to treat malignant diseases. In the present study, we investigated the differential cytotoxic effects of H. niger on human tumour and healthy cells of the human immune system in vitro. MATERIAL AND METHODS: Protoanemonin and saponins, as significant constituents of H. niger extracts, were quantified in five individual batches using validated HPLC methods. Further, the impact of H. niger on proliferation capacity (MTT assay) as well as on apoptosis and necrosis induction in a panel of tumour cell lines and human lymphocytes (combined annexin V and propidium iodide staining) was monitored. In addition, NK cell function (degranulation-CD107a assay and IFN-gamma secretion) was also investigated since these immunocompetent cells are important for the control of malignancies within the human body. RESULTS: Extracts of H. niger induced proliferation inhibition not only of lymphoblastic leukaemia cells (MOLT4; IC50: 171 µg/mL) but also of myosarcoma (SK-UT-1b; IC50: 304 µg/mL) and melanoma cells (HT-144; IC50: 569 µg/mL) due to the induction of apoptosis. Purified T cells or NK cells were significantly affected through the presence of high H. niger concentrations while bulk lymphocytes were not affected. NK cells' anti-tumour functions expressed by degranulation capacity as well as IFN-y production were unaffected by the presence of the H. niger extract. Since protoanemonin and saponins have been reported in the literature to exert cytotoxic effects, their content was also determined. CONCLUSIONS: H. niger extracts exhibit differential cytotoxicity towards tumour cell lines and healthy human T- and NK-cells.

LC-MS(n) characterization of steroidal saponins in Helleborus niger L. roots and their conversion products during fermentation.

Steroidal saponins comprise a substantial part of the secondary metabolite spectrum in the medicinal plant Helleborus niger L. (black hellebore). The saponin fraction from the roots was investigated by LC-MS(n) resulting in 38 saponins and ß-ecdysone. Nine diosgenyl-type glycosides, mainly furostanols consisting of the aglycones diosgenin, macranthogenin, sceptrumgenin, and sarsasapogenin were accompanied by 5 diosgenyl-type saponins exhibiting an aglycone with an additional OH group. However, the most relevant compounds were 24 acetylated polyhydroxy saponins including hellebosaponins A and D. The enzymes glucuronidase, ß-glucosidase, and pectinase were used to obtain an idea on potential fermentative transformation reactions by incubation of the isolated model saponins macranthosid I and hellebosaponin A. In a second step, aqueous H. niger extracts containing a much greater range of saponins were monitored during fermentation and 12months of storage. The metabolites were examined and assigned by LC-MS(n) and targeted extracted ion current (EIC) scan analyses. Good agreement was found among the results from the model compounds and the whole aqueous fermented extracts. The native diosgenyl-type furostanol saponins were converted to spirostanols under scission of hexoses. Alteration of the acetylated polyhydroxy saponins, exclusively spirostanols, took place following cleavage of acetyl groups and terminal deoxyhexoses. Most interestingly, the pentoses of the sugar chain at C(1) were not affected. Conversion of acetylated polyhydroxy saponins resulted in a final structure type which was stable and detectable, even after 12months of fermentation and storage.

Comprehensive study of the phenolics and saponins from Helleborus niger L. Leaves and stems by liquid chromatography/tandem mass spectrometry.

The aerial parts of the medicinal plant Helleborus niger L. comprise a substantial number of constituents with only few of them identified so far. To expand the knowledge of its secondary metabolite profile, extracts from H. niger leaves and stems were investigated by liquid chromatography/tandem mass spectrometry (LC/MS(n) ). Specific identification strategies using LC/MS are established and discussed in detail. The leaves turned out to contain acylated and non-acylated quercetin and kaempferol oligoglycosides, protoanemonin and its precursor ranunculin, ß-ecdysone, and a variety of steroidal saponins, mainly in the furostanol form. The sapogenins were elucidated as of sarsasapogenyl, diosgenyl, and macranthogenyl structures, and confirmed by comparison with the respective reference compounds. The secondary metabolite profiles were almost identical in both plant parts except that the stems lacked kaempferol derivatives and some saponins. The ranunculin derivatives and ß-ecdysone were found in both plant parts. Correlations between the location of the compound groups and the plant's defense strategies are proposed. Additionally, the role of the detected secondary metabolites as protective substances against exogenic stress and as a defense against herbivores is discussed.

Neuroprotective potential of Laurus nobilis antioxidant polyphenol-enriched leaf extracts.

Oxidative stress has been proposed to be an important factor in the pathogenesis of Alzheimer's disease (AD), playing a central role in amyloid ß-protein (Aß) generation and neuronal apoptosis. Oxidative damage directly correlates with the presence of Aß deposits. Aß and oxidative stress jointly induce neuronal death, Aß deposits, gliosis, and memory impairment in AD. In order to counteract AD neurodegeneration, the inhibition of the vicious cycle of Aß generation and oxidation is an attractive therapeutic strategy, and antiamyloidogenic and antioxidant herbal drugs could represent an alternative and valid approach. In this context, an alcoholic extract from Laurus nobilis leaves (LnM) and seven fractions obtained therefrom were of interest. All extracts prepared through extractive and chromatographic techniques were phytochemically studied by chromatographic techniques including gas chromatography-mass spectrometry (GC-MS) and liquid chromatography-tandem mass spectrometry (LC-MS(n)). The potential antioxidant efficacy of the obtained fractions was screened by DPPH(•) and ABTS(•+) assays, as well as specific assay media characterized from the presence of highly reactive ROS and RNS species (ROO(•), OH(•), O2(•-), and NO). In order to evaluate the preparation of safe and nontoxic extracts, MTT, SRB, and LDH assays toward SH-5YSY and SK-N-BE(2)-C human neuronal cell lines, as well as on C6 mouse glial cell line, were performed. The apoptosis-inducing properties by spectroscopic evaluation of the extracts' ability to activate caspase-3 and by a DNA fragmentation assay were also investigated. Data thus obtained allowed us to state the absence of toxic effects induced by phenolic-rich fractions (LnM, LnM-1, LnM-1a, LnM-1b, and LnM-2c), which at the same time exerted significant cytoprotective and antioxidant responses in hydrogen peroxide and Aß(25-35)-fragment-oxidized cell systems. The potential antiamyloidogenic efficacy of Laurus nobilis leaf polar extracts in the Aß(25-35) fragment oxidized cell systems was further analyzed by Congo red staining.

Tandem mass spectrometric characterization of acetylated polyhydroxy hellebosaponins, the principal steroid saponins in Helleborus niger L. roots(#).

RATIONALE: Isolation and extensive nuclear magnetic resonance (NMR) analyses revealed polyhydroxy steroid saponins to be characteristic constituents in Helleborus niger L. roots. A comprehensive study including various multi-stage mass spectrometry (MS(n) ) experiments provided first solid chromatographic and mass spectrometric information facilitating future analysis and structural assessment of polyhydroxy saponins by LC/MS(n) techniques without isolation and NMR analyses. METHODS: The polyhydroxy saponins were analyzed by direct syringe injection or chromatographically separated on a capillary high-performance liquid chromatography (HPLC) system coupled to an electrospray ionization (ESI) source. MS(n) spectra were recorded on an ion trap mass spectrometer including up to four fragmentation stages (LC/ESI-MS/MS). Additionally, high-resolution mass spectra were recorded on an Orbitrap Fourier transform (FT) mass spectrometer equipped with a nanospray-ESI interface. RESULTS: The polyhydroxy hellebosaponins A and D were discovered to be significant constituents from H. niger roots. Extensive study of their MS(n) data revealed that they readily fragmented in the positive ion mode providing diagnostic fragments for elucidation of the steroidal character and number of OH groups. The negative ion mode yielded valuable information on the [M-H](-) ion, number and location of acetyl groups and sugar units. Additionally, fragmentation pathways for positive and negative ion modes were proposed. CONCLUSIONS: These results not only extend the knowledge about H. niger saponins, but also provide a facilitated approach to the analysis of polyhydroxy saponins by LC/MS(n) without prior isolation and extensive NMR identification. Additionally, proposed fragmentation pathways for positive and negative ionization modes provide a solid complementary database for further, more detailed MS(n) studies.

Phenolic constituents from Alchemilla vulgaris L. and Alchemilla mollis (Buser) Rothm. at different dates of harvest.

Acetone/water extracts from the leaves, including stalks, of Alchemilla vulgaris L. and A. mollis (Buser) Rothm. were investigated for their phenolic composition by liquid chromatography-tandem mass spectrometry (LC-MS/MS). A total of 24 and 27 compounds were detected for A. vulgaris and A. mollis, respectively. Pedunculagin and agrimoniin, as described in earlier reports for A. vulgaris, as well as other monomeric and oligomeric ellagitannins such as sanguiin H-10, castalagin/vescalagin, and galloyl-bis-hexahydroxydiphenoyl (HHDP) hexose constituted the major phenolic fraction of both plant species. Also, gallic and chlorogenic acids were found in both extracts. Interestingly, catechin and a procyanidin trimer were detected only in A. mollis. The flavonoid fraction comprised quercetin glucuronide as major compound in addition to several other quercetin glycosides. Most interestingly, a tentatively identified kaempferol glucuronide and a methylated quercetin glucuronide were exclusively found in A. mollis. Finally, the overall phenolic fingerprints of both Alchemilla species, harvested in May and August, i.e. at the beginning and the end of the flowering period, were compared. A general accumulation of phenolic constituents was observed later in the year, especially with regard to the ellagitannins.

Conversion of phenolic constituents in aqueous Hamamelis virginiana leaf extracts during fermentation.

INTRODUCTION: Hamamelis virginiana, known for its high level of tannins and other phenolics is widely used for treatment of dermatological disorders. Although reports on hydroalcoholic and aqueous extracts from Hamamelis leaf and bark exist, knowledge on fermented leaf preparations and the underlying conversion processes are still scant. OBJECTIVE: Aqueous Hamamelis leaf extracts were monitored during fermentation and maturation in order to obtain an insight into the bioconversion of tannins and other phenolics. METHODOLOGY: Aliquots taken during the production period were investigated by HPLC-DAD-MS/MS as well as GC-MS after derivatisation into the corresponding trimethylsilyl compounds. RESULTS: In Hamamelis leaf extracts, the main constituents exhibited changes during the observational period of 6 months. By successive depside bond cleavage, the gallotannins were completely transformed into gallic acid after 1 month. Although not completely, kaempferol and quercetin glycosides were also converted during 6 months to yield their corresponding aglycones. Following C-ring fission, phloroglucinol was formed from the A-ring of both flavonols. The B-ring afforded 3-hydroxybenzoic acid from quercetin and 3,4-dihydroxybenzoic acid as well as 2-(4-hydroxyphenyl)-ethanol from kaempferol. Interestingly, hydroxycinnamic acids remained almost stable in the same time range. CONCLUSION: The present study broadens the knowledge on conversion processes in aqueous fermented extracts containing tannins, flavonol glycosides and hydroxycinnamic acids. In particular, the analogy between the microbial metabolism of phenolics from fermented Hamamelis extracts, fermented sourdough by heterofermentative lactic acid bacteria or conversion of phenolics by the human microbial flora is indicated.

An approach to the chemotaxonomic differentiation of two European dog's mercury species: Mercurialis annua L. and M. perennis L.

Mercurialis annua and M. perennis are medicinal plants used in complementary medicine. In the present work, analytical methods to allow a chemotaxonomic differentiation of M. annua and M. perennis by means of chemical marker compounds were established. In addition to previously published compounds, the exclusive presence of pyridine-3-carbonitrile and nicotinamide in CH(2) Cl(2) extracts obtained from the herbal parts of M. annua was demonstrated by GC/MS. Notably, pyridine-3-carbonitrile was identified for the first time as a natural product. Further chromatographic separation of the CH(2) Cl(2) extracts via polyamide yielded a MeOH fraction exhibiting a broad spectrum of side-chain saturated n-alkylresorcinols. While the n-alkylresorcinol pattern was similar for both plant species, some specific differences were observed for particular n-alkylresorcinol homologs. Finally, the investigation of H(2) O extracts by LC/MS/MS revealed the presence of depside constituents. Whereas, in M. perennis, a mixture of mercurialis acid (=(2R)-[(E)-caffeoyl]-2-oxoglutarate) and phaselic acid (=(E)-caffeoyl-2-malate) could be detected, in M. annua solely phaselic acid was found. By comparison with synthesized enantiomerically pure (2R)- and (2S)-phaselic acids, the configuration of the depside could be determined as (2S) in M. annua and as (2R) in M. perennis.

Phenolic constituents from Alchemilla vulgaris L. and Alchemilla mollis (Buser) Rothm. at different dates of harvest.

Acetone/water extracts from the leaves, including stalks, of Alchemilla vulgaris L. and A. mollis (Buser) Rothm. were investigated for their phenolic composition by liquid chromatography-tandem mass spectrometry (LC-MS/MS). A total of 24 and 27 compounds were detected for A. vulgaris and A. mollis, respectively. Pedunculagin and agrimoniin, as described in earlier reports for A. vulgaris, as well as other monomeric and oligomeric ellagitannins such as sanguiin H-10, castalagin/vescalagin, and galloyl-bis-hexahydroxydiphenoyl (HHDP) hexose constituted the major phenolic fraction of both plant species. Also, gallic and chlorogenic acids were found in both extracts. Interestingly, catechin and a procyanidin trimer were detected only in A. mollis. The flavonoid fraction comprised quercetin glucuronide as major compound in addition to several other quercetin glycosides. Most interestingly, a tentatively identified kaempferol glucuronide and a methylated quercetin glucuronide were exclusively found in A. mollis. Finally, the overall phenolic fingerprints of both Alchemilla species, harvested in May and August, i.e. at the beginning and the end of the flowering period, were compared. A general accumulation of phenolic constituents was observed later in the year, especially with regard to the ellagitannins.

Investigations into the phenolic constituents of dog's mercury (Mercurialis perennis L.) by LC-MS/MS and GC-MS analyses.

INTRODUCTION: Dog's mercury (Mercurialis perennis L.) is a traditional European medicinal plant considered as a rich source of bioactive natural products. Yet phytochemical data of the plant are scant. OBJECTIVE: This study aimed to identify the hydrophilic phenolic constituents from M. perennis by aqueous and hydroalcoholic extraction. METHODOLOGY: Extracts of herbal parts were investigated in-depth by HPLC(DAD)-MS/MS and GC/MS analyses. In addition, a novel compound was isolated and fully characterised by 1- and 2D-NMR experiments. RESULTS: Several conjugates of caffeic, p-coumaric and ferulic acids together with glucaric or 2-hydroxyglutaric acids (depsides) were detected in the aqueous extracts from aerial plant parts by use of LC-MS/MS techniques as well UV-spectral data. By implementation of preparative chromatography on polyamide pretreated with formic acid followed by vacuum liquid chromatography on reversed-phase C(18) -silica, one of the predominant depsides was isolated as a pure compound. The NMR spectra ((1) H and (13) C NMR) together with 2D-hetereonuclear multiple bond correlation NMR experiments (gHMBC and gHSQC) and chiral GC investigation, allowed identification of this compound as (-)-(E)-caffeoyl-2-(R)-oxoglutarate. This structure was additionally supported by GC/MS data after silylation and methylation reactions. The hydroalcoholic extract from aerial parts was separated by solvent partition between ethyl acetate and n-butanol. The latter fraction (n-butanol) yielded a mixture of mono- and oligo-glycosides of kaempferol and quercetin, all of them being assigned by LC-MS/MS. CONCLUSIONS: The present investigation constitutes the first comprehensive report on the hydrophilic constituents of the rarely studied plant Mercurialis and thus completes the phytochemical knowledge on M. perennis.

Investigation on the phenolic constituents in Hamamelis virginiana leaves by HPLC-DAD and LC-MS/MS.

Aqueous and acetone/water extracts from Hamamelis virginiana leaves were investigated to obtain a thorough insight into their phenolic composition. To secure compound integrity, a gentle extraction method including the exclusion of light was used. Liquid chromatography tandem mass spectrometry (LC-MS/MS) analyses yielded a fingerprint including 27 phenolic constituents. Quantification of the key compounds on an equivalent basis by high-performance liquid chromatography diode-array detection (HPLC-DAD) showed that gallotannins consisting of six to 11 galloyl units constitute the main fraction, whereas procyanidins and catechin represented only a minor part. Closer inspection revealed that both extracts possess virtually the same galloyl hexose distribution, and the octagalloyl hexose represents the major tannin constituent. Additionally, eight flavonol glycosides and their corresponding aglycones quercetin and kaempferol, as well as three chlorogenic acid isomers and other hydroxycinnamic acids, were identified. Moreover, stability studies on the aqueous extract (5 °C, dark; room temperature, dark; room temperature, light) revealed that the phenolic profile underwent changes when exposed to light. Especially the gallotannins proved to be considerably unstable which may result in phytochemically altered Hamamelis leaf extracts upon transport and storage.