High performance liquid chromatography/electrospray mass spectrometry of Hypericum perforatum extracts

Hyperforin: A natural lead compound with multiple pharmacological activities

Hypericum perforatum L. (Clusiaceae), commonly known as St. John's wort, has a rich historical background as one of the oldest and most widely studied herbal medicines. Hyperforin is the main antidepressant active ingredient of St. John's wort. In recent years, hyperforin has attached increasing attention due to its multiple pharmacological activities. In this review, the information on hyperforin was systematically summarized. Hyperforin is considered to be a lead compound with diverse pharmacological activities including anti-depression, anti-tumor, anti-dementia, anti-diabetes and others. It can be obtained by extraction and synthesis. Further pharmacological studies and more precise detection methods will help develop a value for hyperforin. In addition, structural modification and pharmaceutical preparation technology will be beneficial to promoting the research progress of hyperforin based innovative drugs. Although these works are full of known and unknown challenges, researchers are still expected to make hyperforin play a greater value.

Micro-nano particulate compositions of Hypericum perforatum L in ultra high diluted succussed solution medicinal products

The fact that many patients all over the world use homeopathic ultra high diluted succussed medicinal products, makes very interesting an explanation about the structure of them since until now only unconfirmed hypotheses are made. The present study focuses on the still unanswered questions about what happens with the chemical composition and the physicochemical properties of these products using Hypericum Perforatum L as a representative paradigm. All samples were prepared according to manufacturing procedures described mainly in S. Hahnemann's “Organon” and were examined by SEM, XRD, FTIR, DLS micro Mastersizer, DLS nano Zetasizer, UV-Vis and TEM. Measurements of electrical conductivity and pH were effectuated by the appropriate devices. During trituration of source material in alpha-lactose monohydrate some functional chemical groups present in source material disappeared and some others new ones came in view at the end of the process. A differentiation upon physicochemical properties between the source material and final triturating product was viewed, as well as micro-nanoparticles in colloidal form in all potencies derived trituration or extraction origin were present. The findings showed that the whole preparation process leads to the creation of micro nanoparticles something that for solid origin these products are created by trituration and for extract origin products these nanoparticles exist from the beginning.

An Investigation on the In Vitro Wound Healing Activity and Phytochemical Composition of Hypericum pseudolaeve N. Robson Growing in Turkey

Objectives

The aim of this study was to investigate the in vitro wound healing effects of the methanolic and aqueous extracts of Hypericum pseudolaeve N. Robson obtained by two different methods as well as its cytotoxicity, antioxidant activity, and selected phytochemical constituents.

Materials and Methods

Total phenolic and flavonoid contents were measured using spectrophotometry-based methods. The cytotoxic effects of the extracts on L929 mouse fibroblast cells were evaluated by and 2h-tetrazolium,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assay. Moreover, migration and spreading of the treated fibroblast cells were assessed by cell scratch assay as an in vitro wound healing model. In addition, the chemical content of the species was determined by high pressure liquid chromatography (HPLC).

Results

The results of the cytotoxicity assay indicated that the methanolic and aqueous extract did not have any cytotoxic effect on fibroblast cells at concentrations up to 500 μg/mL. Fibroblast migration was significantly increased by 62 μg/mL concentration of the aqueous extracts compared to the negative control. The extracts showed good antioxidant activity and 16 phytochemical compounds were detected by HPLC, with the highest amount for epicatechin.

Conclusion

The results showed that Hypericum pseudolaeve extracts have wound healing potential and contain several important antioxidant phenolic compounds. This species deserves further investigation aiming to isolate and identify the active compounds.

Aromaticity and Electron Density of Hypericin

The influence of the substituents on the geometry of the central ring system of hypericin has been analyzed. Substitution that causes flattening of the hypericin central rings is connected with introducing the aromatic character of the empty rings. All the hypericin rings have an aromatic character illustrated by the Harmonic Oscillator Measure of Aromaticity (HOMA), Nucleus Independent Chemical Shift (NICS), Fluctuation Index (FLU), and Ellipticity Index (EL) indices. Quantum Theory of Atoms in Molecules (QTAIM) and Natural Bond Orbital (NBO) analyses performed on 7,14-dihydrophenanthro[1,10,9,8-opqra]perylene, its substituted analogues, and hypericin show an influence of this substitution on electron density of the central rings.

Highly efficient green synthesis and photodynamic therapeutic study of hypericin and its derivatives

A highly efficient synthetic pathway for hypericin (7a) was achieved under mild conditions with an overall yield over two steps of 92% using emodinanthrone as a starting material, where protohypericin, a key precursor of hypericin, was synthesized in water with microwave assistance, which was then photocyclized to hypericin with a high yield via 1 h irradiation in a visible light reactor equipped with 575 nm monochromatic lamps. In addition, the method could be used to synthesize hypericin derivatives (7b–d) with similar overall yields. Furthermore, their effects of photodynamic therapy (PDT) were evaluated on A431, HepG-2, and MCF-7 cell lines. The PDT of 7b was better than that of 7a, whereas 7c and 7d were worse. Unlike other cell lines, MCF-7 was not sensitive to any of 7a–d at the same concentrations.

A highly efficient synthetic pathway for hypericin as well as its derivatives was achieved under mild and green conditions with high yields.

Quality control of Hypericum perforatum L. analytical challenges and recent progress

Objectives

The most widely applied qualitative and quantitative analytical methods in the quality control of Hypericum perforatum extracts will be reviewed, including routine analytical tools and most modern approaches.

Key findings

Biologically active components of H. perforatum are chemically diverse; therefore, different chromatographic and detection methods are required for the comprehensive analysis of St. John's wort extracts. Naphthodianthrones, phloroglucinols and flavonoids are the most widely analysed metabolites of this plant. For routine quality control, detection of major compounds belonging to these groups seems to be sufficient; however, closer characterization requires the detection of minor compounds as well.

Conclusions

TLC and HPTLC are basic methods in the routine analysis, whereas HPLC-DAD is the most widely applied method for quantitative analysis due to its versatility. LC-MS is gaining importance in pharmacokinetic studies due to its sensitivity. Modern approaches, such as DNA barcoding, NIRS and NMR metabolomics, may offer new possibilities for the more detailed characterization of secondary metabolite profile of H. perforatum extracts.

HPLC-UV-ESI-MS analysis of phenolic compounds and antioxidant properties of Hypericum undulatum shoot cultures and wild-growing plants

LC-UV and LC-MS analysis were used to study the phenolic composition of water extracts of Hypericum undulatum (HU) shoot cultures and wild-growing (WG) plants. Total phenolic content (TPC), determined using the Folin-Ciocalteu assay, and the antioxidant activity measured by two complementary methods were also performed for each sample. Mass spectrometry revealed several phenolics acids with quinic acid moieties, flavonols, mostly quercetin, luteolin and apigenin glycosides, flavan-3-ols (catechin and epicatechin) and the xanthonoid mangiferin. Differences in phenolic composition profile and TPC were found between the samples. The major phenolic in HU culture-growing (CG) samples is chlorogenic acid, followed by epicatechin, quercitrin and isoquercitrin. The WG plants presents hyperoside as the main phenolic, followed by isoquercitrin, chlorogenic acid and quercetin. The TPC and antioxidant activity were higher in samples from WG plants.

Antioxidant activity relationship of phenolic compounds in Hypericum perforatum L

BACKGROUND

The St John's Wort (Hypericum perforatum; Clusiaceae) has been used in traditional and modern medicine for a long time due to its high content of biologically active phenolics. The purpose of this work was to develop a method for their fractionation and identification, and to determine the most active antioxidant compounds in plant extract.

RESULTS

An LC-MS method which enables fast qualitative and semiquantitative analysis was developed. The composition determined is in agreement with the previous results, where 6 flavonoids, 4 naphthodianthrones and 4 phloroglucinols have been identified. Significant antioxidant activity was determined for most of the fractions by DPPH assay (the lowest IC50 of 0.52 μg/ml), NO scavenging (6.11 μg/ml), superoxide scavenging (1.86 μg/ml), lipid peroxidation (0.0079 μg/ml) and FRAP (the highest reduction capacity of 104 mg Fe equivalents/g) assays.

CONCLUSION

LC-MS technique has been successfully applied for a quick separation and identification of the major components of H. perforatum fractions. Majority of the fractions analyzed have expressed a very high antioxidative activity when compared to synthetic antioxidants. The antioxidant activity could be attributed to flavonoids and phenolic acids, while phloroglucinols and naphthodianthrones showed no significant activity. It is demonstrated that it is possible to obtain, by fractionation, H. perforatum preparations with significantly increased phloroglucinols-to-naphthodianthrones ratio (up to 95:5).

A Semiquantitative FIA-ESI-MS Method for the Rapid Screening of Hypericum perforatum Crude Extracts

A method based on FIA-ESI-MS has been developed to profile the major constituents of Hypericum perforatum extracts. The objective was to obtain simultaneous semi-quantitative data on hypericin, chlorogenic acid, rutin, quercitrin, quercetin and hyperforin contents for a high-throughput screening of the raw plant material. The principal drawback of FIA-ESI analysis of complex mixtures involves ion suppression effects: the ionization of some components of the mixture can be severely suppressed by ionization of others. The results show that this problem can be alleviated using a new approach to generate calibration curves.

Quantitative analysis of the major constituents of St John's wort with HPLC-ESI-MS

A method was developed to profile the major constituents of St John's wort extracts using highperformance liquid chromatography-electrospray mass spectrometry (HPLC-ESI-MS). The objective was to simultaneously separate, identify and quantify hyperforin, hypericin, pseudohypericin, rutin, hyperoside, isoquercetrin, quercitrin and chlorogenic acid using HPLC-MS. Quantification was performed using an external standardisation method with reference standards. The method consisted of two protocols: one for the analysis of flavonoids and glycosides and the other for the analysis of the more lipophilic hypericins and hyperforin. Both protocols used a reverse phase Luna phenyl hexyl column. The separation of the flavonoids and glycosides was achieved within 35 min and that of the hypericins and hyperforin within 9 min. The linear response range in ESI-MS was established for each compound and all had linear regression coefficient values greater than 0.97. Both protocols proved to be very specific for the constituents analysed. MS analysis showed no other signals within the analyte peaks. The method was robust and applicable to alcoholic tinctures, tablet/capsule extracts in various solvents and herb extracts. The method was applied to evaluate the phytopharmaceutical quality of St John's wort preparations available in the UK in order to test the method and investigate if they contain at least the main constituents and at what concentrations.

Hypericins as potential leads for new therapeutics

70 years have passed since the first isolation of the naphthodianthrones hypericin and pseudohypericin from Hypericum perforatum L. Today, they continue to be one of the most promising group of polyphenols, as they fascinate with their physical, chemical and important biological properties which derive from their unique chemical structure. Hypericins and their derivatives have been extensively studied mainly for their antitumor, antiviral and antidepressant properties. Notably, hypericin is one of the most potent naturally occurring photodynamic agents. It is able to generate the superoxide anion and a high quantum yield of singlet oxygen that are considered to be primarily responsible for its biological effects. The prooxidant photodynamic properties of hypericin have been exploited for the photodynamic therapy of cancer (PDT), as hypericin, in combination with light, very effectively induces apoptosis and/or necrosis of cancer cells. The mechanism by which these activities are expressed continues to be a main topic of discussion, but according to scientific data, different modes of action (generation of ROS & singlet oxygen species, antiangiogenesis, immune responces) and multiple molecular pathways (intrinsic/extrinsic apoptotic pathway, ERK inhibition) possibly interrelating are implicated. The aim of this review is to analyse the most recent advances (from 2005 and thereof) in the chemistry and biological activities (in vitro and in vivo) of the pure naphthodianthrones, hypericin and pseudohypericin from H. perforatum. Extracts from H. perforatum were not considered, nor pharmakokinetic or clinical data. Computerised literature searches were performed using the Medline (PubMed), ChemSciFinder and Scirus Library databases. No language restrictions were imposed.

Dereplication of bioactive constituents of the genus hypericum using LC-(+,-)-ESI-MS and LC-PDA techniques: Hypericum triquterifolium as a case study

Utilizing liquid chromatography-electro spray ionization-mass spectrometry (LC-(+,-)-ESI-MS) and liquid chromatography-photodiode array detection (LC-PDA) techniques, a dereplication strategy for the analysis of the secondary metabolites constituents of the genus Hypericum has been developed. From the crude methanolic extract of the aerial parts of H. triquetrifolium (leaves, stems, and flowers) and on the basis of their UV-profiles, chromatographic retention times and (+,-)-ESI-MS (TIC and SIM) mass spectral data, seven known (1-7) compounds were dereplicated fairly rapidly. The compounds were classified into three structural classes: phloroglucinols: hyperfirin and adhyperfirin; naphthodianthrones: hypericin, pseudo-hypericin, proto-hypericin, and protopseudo-hypericin; and the flavonoid rutin.

Identification of the major constituents of Hypericum perforatum by LC/SPE/NMR and/or LC/MS

The newly established hyphenated instrumentation of LC/DAD/SPE/NMR and LC/UV/(ESI)MS techniques have been applied for separation and structure verification of the major known constituents present in Greek Hypericum perforatum extracts. The chromatographic separation was performed on a C18 column. Acetonitrile-water was used as a mobile phase. For the on-line NMR detection, the analytes eluted from column were trapped one by one onto separate SPE cartridges, and hereafter transported into the NMR flow-cell. LC/DAD/SPE/NMR and LC/UV/MS allowed the characterization of constituents of Greek H. perforatum, mainly naphtodianthrones (hypericin, pseudohypericin, protohypericin, protopseudohypericin), phloroglucinols (hyperforin, adhyperforin), flavonoids (quercetin, quercitrin, isoquercitrin, hyperoside, astilbin, miquelianin, I3,II8-biapigenin) and phenolic acids (chlorogenic acid, 3-O-coumaroylquinic acid). Two phloroglucinols (hyperfirin and adhyperfirin) were detected for the first time, which have been previously reported to be precursors in the biosynthesis of hyperforin and adhyperforin.

Simultaneous determination of benzophenones and gentisein in Hypericum annulatum Moris by high-performance liquid chromatography

The content of the benzophenones, hypericophenonoside, neoannulatophenonoside, annulatophenonoside, annulatophenone, acetylannulatophenonoside and the xanthone derivative gentisein have been determined in aerial parts, leaves, flowers and stems of Hypericum annulatum Moris. Extraction of samples with methanol by magnetic stirring at room temperature allowed a good recovery of analytes (from 90.70% for gentisein to 103.81% for annulatophenonoside) and the precision of the entire procedure was < 6.05%. The subsequent HPLC separation and quantification was achieved using a Hypersil ODS C18 column and UV detection at 290 nm. The mobile phase comprised methanol and 20 mm potassium dihydrogen phosphate (adjusted to a pH of 3.19 with o-phosphoric acid), and gradient elution mode was applied. The detection limits were 0.03, 0.02 and 0.001 microg/mL for hypericophenonoside, acetylannulatophenonoside and gentisein, respectively. The total amounts of the phenolic compounds assayed ranged from 10.92 mg/g in stems to 82.86 mg/g in leaves. Hypericophenonoside was the dominant benzophenone present in the majority of the plant samples, being present in amounts between 7.54 +/- 0.25 mg/g in stems and 64.22 +/- 2.44 mg/g in leaves. Hypericophenonoside accounted for up to 77.50% of the components found in the leaves, whereas annulatophenonoside (6.29 +/- 0.15 mg/g) and acetylannulatophenonoside (8.95 +/- 0.09 mg/g) were detected in much lower quantities. In contrast to leaves, flowers showed a tendency towards higher contents of gentisein (9.35 +/- 0.07 mg/g) and neoannulatophenonoside (4.72 +/- 0.04 mg/g) than the other parts assayed.

Analysis of selected constituents in methanolic extracts ofHypericum perforatum collected in different localities by capillary ITP-CZE

The on-line combination of CZE with capillary ITP (ITP-CZE) was used for the separation and quantification of selected flavonoids and phenolic acids in Hypericum perforatum leaves and flowers collected in six different localities in Slovakia. The leading electrolyte in the ITP preseparation step was 10 mM HCl with Tris as counterion (pH* 7.2). The terminating electrolyte was 50 mM boric acid of pH* 8.2 (adjusted with barium hydroxide). The BGE in the electrophoretic step contained 25 mM beta-hydroxy-4-morpholinopropanesulfonic acid (MOPSO), 50 mM Tris, 65 mM boric acid, pH* 8.3. The content of methanol in all electrolytes was 20% v/v. The total time of the analysis (including the preseparation step) was approximately 35 min. The rectilinear calibration ranges were between 0.125 and 5.0 microg/mL with kaempferol as internal standard. The correlation coefficients ranged between 0.9912 (for quercitrin and chlorogenic acid) and 0.9988 (for isoquercitrin). The RSD values are between 0.86 and 7.78% (n = 6) when determining rutin and quercetin (4 microg/mL). The optimized method was employed for the assay of flavonoids in medicinal plant extract of different collections of Hypericum perforatum haulm. The variability of the content of the active components depending on the place of collection was confirmed.

A high-performance liquid chromatography with electrochemical detection for the determination of total hypericin in extracts of St. John's Wort

An HPLC method for the quantitation of hypericin using a new and sensitive amperometric detection is presented. Hypericin was eluted isocratically using a mobile phase consisting of ammonium acetate, methanol and acetonitrile. The oxidation was carried out with a glassy carbon electrode at a potential of + 1.1 V vs. an Ag-AgCl-KCl reference electrode. Under the conditions described, hypericin was separated at a retention time (Rt) of 12 min. Linearity was obtained over the range 0.035-1.30 microg/mL (r = 0.9994). The limit of detection was determined to be 0.010 ng on-column for hypericin. The method was applied to the determination of total hypericin (hypericin, pseudohypericin, protohypericin and protopseudohypericin) in extracts of St. John's wort using hypericin as an external standard. The protoforms were converted into hypericin and pseudohypericin by subjecting the sample to artificial light prior to chromatographic analysis. For the evaluation of total hypericin, the peak areas of pseudohypericin (Rt 3.7 min) and hypericin (Rt 12.0 min) were combined. The relative standard deviation in analysing samples containing Hypericum ranged from 2.5 to 5.4%.

Herbal remedies: effects on clinical laboratory tests

CONTEXT

Complementary and alternative medicine (herbal medicines) can affect laboratory test results by several mechanisms.

OBJECTIVE

In this review, published reports on effects of herbal remedies on abnormal laboratory test results are summarized and commented on.

DATA SOURCES

All published reports between 1980 and 2005 with the key words herbal remedies or alternative medicine and clinical laboratory test, clinical chemistry test, or drug-herb interaction were searched through Medline. The authors' own publications were also included. Important results were then synthesized.

DATA SYNTHESIS

Falsely elevated or falsely lowered digoxin levels may be encountered in a patient taking digoxin and the Chinese medicine Chan Su or Dan Shen, owing to direct interference of a component of Chinese medicine with the antibody used in an immunoassay. St John's wort, a popular herbal antidepressant, increases clearance of many drugs, and abnormally low cyclosporine, digoxin, theophylline, or protease inhibitor concentrations may be observed in a patient taking any of these drugs in combination with St John's wort. Abnormal laboratory results may also be encountered owing to altered pathophysiology. Kava-kava, chaparral, and germander cause liver toxicity, and elevated alanine aminotransferase, aspartate aminotransferase, and bilirubin concentrations may be observed in a healthy individual taking such herbal products. An herbal product may be contaminated with a Western drug, and an unexpected drug level (such as phenytoin in a patient who never took phenytoin but took a Chinese herb) may confuse the laboratory staff and the clinician.

CONCLUSIONS

Use of alternative medicines may significantly alter laboratory results, and communication among pathologists, clinical laboratory scientists, and physicians providing care to the patient is important in interpreting these results.

Development and evaluation of methods for determination of naphthodianthrones and flavonoids in St. John's wort

Several major constituents in St. John's wort were determined for a homogenized plant sample. Three extraction techniques were evaluated: Soxhlet extraction, pressurized-fluid extraction (PFE), and sonication extraction. Levels of nine constituents (chlorogenic acid, rutin, hyperoside, isoquercitrin, quercitrin, quercetin, amentoflavone, pseudohypericin, and hypericin) were measured using liquid chromatography with ultraviolet/visible absorbance, mass spectrometric, and fluorescence detection. Levels of total naphthodianthrones determined by liquid chromatography (LC) with absorbance detection at 590 nm were compared with levels determined by direct spectrophotometry at the same wavelength. Additionally, the methods described in this paper were applied to several brands of St. John's wort finished products.

Mass spectral characterization of phloroglucinol derivatives hyperforin and adhyperforin

Active phloroglucinol constituents of Hypericum perforatum (St. John's wort) extracts, hyperforin and adhyperforin, have been studied following ion activation using tandem mass spectrometry (MS/MS) and complemented by accurate mass measurements. These two compounds were readily analyzed as protonated and deprotonated molecules with electrospray ionization. MS/MS and MS3 data from a quadrupole-linear ion trap tandem mass spectrometer were employed to elucidate fragmentation pathways. Fourier transform ion cyclotron resonance measurements afforded excellent mass accuracies for the confirmation of elemental formulae of product ions formed via infrared multiphoton dissociation and sustained off-resonance irradiation collision-induced dissociation. Fragmentation schemes have been devised for the dissociation of hyperforin and adhyperforin in negative and positive ion modes. This information is expected to be especially valuable for the characterization of related compounds, such as degradation products, metabolites and novel synthetic analogs of hyperforin.

Chromatographic performance of a new polar poly(ethylene glycol) bonded phase for the phytochemical analysis of Hypericum perforatum L

The aim of this study was to evaluate the chromatographic performance of a poly(ethylene glycol) (PEG) stationary phase for the HPLC analysis of the secondary metabolites (chlorogenic acid, flavonoids, phloroglucinols and naphthodianthrones) in methanolic extracts of Hypericum perforatum L. (St. John's Wort) flowering tops, herbal medicinal products and dietary supplements. A fast and reliable method was developed. The analyses were carried out on a Supelco Discovery HS PEG column (150 mm x 4.6 mm i.d., 5 microm). A gradient mobile phase, composed of 0.1 M aqueous acetic acid solution (pH 2.8) and methanol-acetonitrile (5:4, v/v), was used. The flow rate was 1 mL/min. The photodiode array detector monitored the eluent at 270 (for chlorogenic acid, flavonoids and phloroglucinols) and 590 nm (for naphthodianthrones). The column was maintained at room temperature. The total running time was 40 min. The method was validated and showed good linearity, precision, accuracy, sensitivity and specificity. Through the above described phytochemical markers, this technique allowed the unequivocal identification and standardization of H. perforatum plant material and phytoproducts. The quantification data highlighted the fact that the products on sale, in particular those labeled as dietary supplements, varied widely in the quantitative composition of the active constituents. The developed method could be considered suitable for the quality control of H. perforatum herb and derivatives.

Liquid chromatography/electrospray ionization mass spectrometry for the characterization of twenty-three flavonoids in the extract of Dalbergia odorifera

A method incorporating high-performance liquid chromatography (HPLC) with electrospray ionization and tandem mass spectrometry, with parallel analysis by HPLC with UV detection using a diode-array detector, was developed for the qualitative characterization of flavonoids in D. odorifera. Twenty-three flavonoids, including six isoflavones, six neoflavones, four isoflavanones, three flavanones, two chalcones, one isoflavanonol and one pterocarpan, were unambiguously identified by comparing their retention times, UV and MS spectra with those of authentic compounds. Furthermore, the collision-induced dissociations of the [M-H]- ions were studied to clarify the MS behavior of the different types of flavonoids. In negative ion ESI-MS all the flavonoids yielded prominent [M-H]- ions in the first order mass spectra. Fragments involving losses of CH3*, H2O, CO, C2H2O, and CO2 were observed in the MS/MS spectra. Each of the seven types of flavonoid showed characteristic MS/MS fragmentation patterns. The isoflavanones, flavanones and chalcones were observed to undergo retro-Diels-Alder fragmentations. The spectra of almost all the neoflavonoids unexpectedly exhibited only [M-H-CH3]-* radical anions as base peaks without any further fragmentation. Substitution positions also remarkably influenced the fragmentation behavior, which could assist in distinction among the flavonoid isomers. The fragmentation rules deduced here could aid in the characterization of other flavonoids of these types.

Development of a high-performance liquid chromatographic method with electrochemical detection for the determination of hyperforin

An HPLC method with electrochemical detection for the determination of hyperforin extracts without using additional sample precleaning has been developed and validated. The hyperforin solutions were separated isocratically using a mobile phase consisting of 10% ammonium acetate buffer (0.5 M, pH 3.7)-MeOH-acetonitrile (10:40:50, v/v) at a flow rate of 0.8 mL/min. Hyperforin was detected amperometrically with a glassy carbon electrode at a potential of +1.1 V versus Ag/AgCl/3 M potassium chloride reference electrode. Under these conditions, a plot of integrated peak area versus concentration of hyperforin was found to be linear over the range of 0.054-5.4 microg/mL, with a relative standard deviation of 2.2-8.6%. The limit of detection was 0.050 ng on column. The determination of the hyperforin content in a commercially available St. John's Wort preparation exhibited a mean content of 1.56 mg. Recovery experiments led to a mean recovery rate of 97 +/- 5.8%. The proposed method is not time-consuming, sensitive and reproducible and is therefore suitable for routine analysis of hyperforin in herbal medicinal products.

Determination of Hyperforin in Mouse Brain by High-Performance Liquid Chromatography/Tandem Mass Spectrometry

Hyperforin is one of the essential active ingredients of St. John's wort extract, which is used as an antidepressant for mild to moderately severe depressions. In vitro and in vivo data as well as several clinical studies and meta analyses have confirmed the pharmacological effect of treatment with hyperforin-containing preparations. However, little is known about the brain availability of hyperforin until now. Accordingly, a highly sensitive and selective LC/MS method for this purpose was developed and validated. This method proved suitable for the determination of hyperforin in mouse brain, after oral administration of hyperforin sodium salt and St. John's wort extract. This method involves liquid-liquid extraction of hyperforin with ethyl acetate followed by separation with rapid reversed-phase high-performance liquid chromatography and tandem mass spectrometry detection using electrospray ionization. Excellent linearity was obtained for the entire calibration range from 0.25 to 10 ng/mL (corresponding to 2.5-100 ng/g brain tissue concentration, calculated with the factor derived from sample processing) with an average coefficient of correlation of 0.9992. The recovery of hyperforin from mouse brain homogenates was between 71.4 and 75.3% with a relative standard deviation of less than 3%. Validation assays for the lower limit of quantitation yielded an accuracy of 5.8%. Intraday accuracy and precision for the developed method were between 4.6 and 10.6% and 4.3-8.4%, respectively, while the interday parameters varied between 6.7 and 12.2% for accuracy and 2.0-5.0% for precision. After the method validation, hyperforin brain levels in mice, treated with 15 mg/kg hyperforin (either as the sodium salt or as 5% St. John's wort extract), were investigated. The average concentration of hyperforin found for the sodium salt group was 28.8+/-10.1 ng/g of brain (n = 8), which was somewhat higher than the hyperforin concentration of 15.8+/-10.9 ng/g of brain (n = 8), determined in the extract-treated group. This method is robust, selective, and highly sensitive and represents an appropriate tool to further prove the occurrence and distribution of hyperforin in mouse brain.

Fast high-performance liquid chromatographic analysis of naphthodianthrones and phloroglucinols from Hypericum perforatum extracts

Hypericum perforatum L. (St. John's Wort) has been used in modern medicine for treatments of depression and neuralgic disorders. An HPLC method with photodiode array detection for the rapid determination of the major active compounds, naphthodianthrones and phloroglucinols, has been developed. The method permits the determination of hypericin, protohypericin, pseudohypericin, protopseudohypericin, hyperforin and adhyperforin in an extract in less than 5 min. Good linearity over the range 0.5-200 microg/mL for hyperforin and 0.02-100 microg/mL for hypericin was observed. Intra-assay accuracy and precision varied from 0.1 to 17% within these ranges. Lower levels of quantitative determination were 2 microg/mL for hyperforin and 0.5 microg/mL for hypericin, while detection limits were 0.1 and 0.02 microg/mL, respectively.

The in vitro effects of Hypericum species on human leukocyte myeloperoxidase activity

Myeloperoxidase (MPO) is a major component of the antimicrobial system of polymorphonuclear neutrophils. The heme enzyme MPO catalyzes the conversion of hydrogen peroxide and chloride to hypochlorous acid. Hypochlorous acid is the major strong oxidant produced by neutrophils and may contribute to inflammatory tissue damage. It was reported that certain antiinflammatory drugs are capable of inhibiting MPO activity and this inhibition may account for their antiinflammatory effect. Hypericum L. is a genus of about 400 species, widespread throughout the world. Some species of genus exhibit a significant antiinflammatory activity beside their several pharmacological properties such as antidepressant, diuretic, antihelmintic, and antibacterial. In this study, we investigated the in vitro effects of three Hypericum species, which exhibit antiinflammatory activity, on human polymorphonuclear leukocyte MPO activity. We found that each extract of Hypericum species reduced the peroxidative and chlorinating activity of human leukocyte MPO in concentration-dependent manner. The antiinflammatory activity of these species may be related with inhibition of MPO activity.

Use of an on-line, precolumn photochemical reactor in high-performance liquid chromatography of naphthodianthrones in Hypericum perforatum preparations

A method has been developed for the determination of naphthodianthrones in Hypericum perforatum L. extracts and phytopharmaceutical preparations by high-performance liquid chromatography combined with on-line, precolumn photochemical conversion followed by photodiode-array detection. The chromatographic separation was performed on a C18 column under isocratic reversed-phase conditions. An on-line, precolumn photochemical reactor equipped with a knitted PTFE reaction coil around a visible light source was used in order to transform the light sensitive naphthodianthrones, protohypericin and protopseudohypericin, very easily into the non-protoforms, hypericin and pseudohypericin, respectively. Two UV chromatograms (photochemical reactor "on" and "off") were compared and were quite useful in characterizing the sample. Validation studies demonstrated that this HPLC method is simple, rapid, reliable and reproducible. The time-consumptive manual irradiation of the samples is omitted by this automated on-line irradiation step. The developed method was successfully applied to the quality control of Hypericum perforatum L. extracts and its phytopharmaceutical preparations.

Determination of hyperforin in human plasma using solid-phase extraction and high-performance liquid chromatography with ultraviolet detection

Hyperforin is one of the most important active components in St. John's wort (Hypericum perforatum), a botanical dietary supplement used as an alternative treatment modality for mild to moderate depression. A solid-phase extraction (SPE) and an isocratic high-performance liquid chromatography (HPLC) analysis with ultraviolet (UV) detection were developed to determine hyperforin in human plasma samples. Benzo[k]fluoranthene was used as an internal standard. The absolute recovery for hyperforin was more than 89% for plasma concentrations ranging from 25 to 500 ng/ml. The linearity of calibration curves, inter-day and intra-day relative standard deviations were investigated. The limit of detection (LOD) of hyperforin was 4 ng/ml in plasma and the limit of quantitation (LOQ) was 10 ng/ml. Hyperforin concentrations in human plasma following St. John's wort administration were analyzed. The result suggests that this method is rapid, sensitive, reproducible and capable of quantitative analysis of hyperforin plasma concentrations.

Analytical methods for quality control of propolis

Propolis is a resinous substance collected by honeybees from leaf buds and cracks in the bark of various plants, and it is composed of 50% resin (composed of flavonoids and related phenolic acids), 30% wax, 10% essential oils, 5% pollen and 5% various organic compounds. Propolis cannot be used as raw material, and it must be purified by extraction with solvents. This process should remove the inert material and preserve the polyphenolic fraction, which is considered to contribute more to the observed healing effects than the other propolis constituents. Therefore, the assay of propolis polyphenols is of interest, and this paper describes the results obtained in the analysis of propolis by means of a gradient HPLC or mass spectrometry. HPLC in the gradient mode and coupled with photodiode array detection remains the method of choice for the assay of most relevant components of propolis. Direct analysis by APCI-IT-MS represents a valuable alternative to obtain typical fingerprints of propolis and a reliable identification of a large number of propolis components.

On-line coupling of capillary isotachophoresis and capillary zone electrophoresis for the determination of flavonoids in methanolic extracts of Hypericum perforatum leaves or flowers

Five flavonoids (hyperoside, isoquercitrin, quercitrin, quercetin and rutin) were separated and determined in extracts of Hypericum perforatum leaves or flowers by capillary zone electrophoresis (CZE) with isotachophoretic (ITP) sample pre-treatment using on-line column coupling configuration. The background electrolyte (BGE) used in the CZE step was different from the leading and terminating ITP electrolytes but all the electrolytes contained 20% (v/v) of methanol. The optimal leading electrolyte was 10 mM HCl of pH* approximately 7.2 (adjusted with Tris) and the terminating electrolyte was 50 mM H3BO3 of pH* approximately 8.2 (adjusted with barium hydroxide). This operational system allowed to concentrate and pre-separate selectively the flavonoid fraction from other plant constituents before the introduction of the flavonoids into the CZE capillary. The BGE for the CZE step was 50 mM Tris buffer of pH* approximately 8.75 containing 25 mM N-[tris(hydroxymethyl)methyl]-3-aminopropanesulfonic acid as co-ion and 55 mM H3BO3 as complex-forming agent. The ITP-CZE method with spectrophotometric detection at 254 nm was suitable for the quantitation of the flavonoids in real natural samples; kaempferol was used as internal standard. The limit of detection for quercetin-3-O-glycosides was 100 ng ml(-1) and calibration curves were rectilinear in the range 1-10 microg ml (-1) for most of the analytes. The RSD values ranged between 0.9 and 2.7% (n=3) when determining approximately 0.07-1.2% of the individual flavonoids in dried medicinal plants.

Supercritical fluid extraction and high-performance liquid chromatographic determination of phloroglucinols in St. John's Wort (Hypericum perforatum L.)

A small-scale supercritical fluid extraction (SFE) method was developed for the selective extraction of phloroglucinols from St. John's wort (SJW) leaf/flower mixtures using supercritical carbon dioxide (CO(2)). The extraction efficiency was investigated as influenced by pressure, temperature, time, and modifier. The optimized condition of SFE was carried out at 3.80 x 10(4) kpa (5500 psi) and 50 degrees C. Samples were held in static extraction for 10 min, followed by a dynamic extraction for 90 min at the flow rate of 1 mL/min. A simple and sensitive HPLC method was developed for the analysis of hyperforin and adhyperforin, the major phloroglucinols, in the SFE extract of SJW.

Determination of naphthodianthrones and phloroglucinols from Hypericum perforatum extracts by liquid chromatography/tandem mass spectrometry

Hypericum perforatum L. (St. John's Wort) has long been known as a medicinal plant, and has been used for the treatment of depression and neuralgic disorders. Its main active constituents are believed to be a naphthodianthrone, hypericin, and a phloroglucinol, hyperforin. A sensitive high performance liquid chromatography (HPLC)/electrospray tandem mass spectrometric method for fast simultaneous determination of six major naphthodianthrones and phloroglucinols of Hypericum perforatum extract has been developed. The method, based on multiple dissociation reaction monitoring (MRM), allows the analysis of hypericin, protohypericin, pseudohypericin, protopseudo-hypericin, hyperforin and adhyperforin from the extract in less than 5 min. Good linearity over the range 0.1-1000 ng/mL for hyperforin and 2-500 ng/mL for hypericin was observed. Intra-assay accuracy and precision varied from 2 to 19% within these ranges. Lower levels of quantitation for hyperforin were 0.5 ng/mL and 2 ng/mL for hypericin.

Development of a simple, rapid and reproducible HPLC assay for the simultaneous determination of hypericins and stabilized hyperforin in commercial St. John's wort preparations

A reversed-phase HPLC method was developed and validated for the simultaneous determination of hypericins and stabilized hyperforin in St. John's wort extract. The sample solution was prepared by extraction of the finely powdered extract with methanol-water (80:20, v/v) containing 5% HP-beta-cyclodextrin, and adjusted to pH 2.5 with orthophosphoric acid. Diluted extract solutions, maintained at 0 degrees C, were injected into a C18 column. The samples were eluted isocratically using a mobile phase consisting of acetonitrile and 0.3% v/v phosphoric acid (90:10, v/v) at a 1.5 ml/min flow rate with simultaneous fluorescence (315/590 nm, excitation/emission) and UV (273 nm) detection. Quantification of the marker compounds (hypericin, pseudohypericin, hyperforin) was achieved by use of standard curves generated by plotting peak heights versus concentrations. Validation studies demonstrated that this HPLC method is simple, rapid, reliable, and reproducible. The standard curves were linear over the concentration ranges, 0.5-2.5 microg/ml (hypericin), 0.35-1.6 microg/ml (pseudohypericin) and 5-50 microg/ml (hyperforin). The intra-day coefficients of variation obtained for hypericin, pseudohypericin and hyperforin were < or = 4.4%, < or = 5.4%, and < or = 2.8%, respectively; inter-day CVs were < or = 5.8%, < or = 4.9%, and < or = 2.5%, respectively. This method may be applied for the routine standardization of St. John's wort products against hyperforin and the hypericins, the putative antidepressant principles in the herbal.

Structure characterization of flavonoid O-diglycosides by positive and negative nano-electrospray ionization ion trap mass spectrometry

Isomeric flavonoid O-diglycosides were analyzed by positive and negative nano-electrospray ionization (ESI) ion trap mass spectrometry (ITMS) in order to evaluate whether the two most common interglycosidic linkage types, i.e. 1 --> 2 and 1 --> 6, found for glycosides containing a rhamnosylglucose glycan part can be differentiated. In the positive ion mode the degree of internal glucose residue loss was found to be strongly dependent on the aglycone type and was very pronounced for aglycones of the flavanone type. The relative abundance of the Y-type ions formed by fragmentation at glycosidic bonds only allows one to infer the interglycosidic linkage types in the case of flavone O-diglycosides. In contrast, the negative ion mode makes a clear differentiation between a rutinoside (1 --> 6) and a neohesperidoside (1 --> 2) glycan residue possible for all aglycone types. The neohesperidose-containing compounds could be characterized by additional product ions. When the compounds were dissolved in pure methanol a molecular radical ion was found to be the base peak in nano-ESI.

Tumor-specific and photodependent cytotoxicity of hypericin in the human LNCaP prostate tumor model

Hypericin (HYP) has been reported to have photodependent cytotoxic activity in a variety of cancer cell lines. However, this activity has yet to be rigorously tested in vivo in tumor models. In this study LNCaP, PC-3 and DU-145 cells were used to test the cytotoxic effects of HYP in vitro, precursory to an in vivo study designed to investigate the effects of HYP in an established murine model for prostate cancer. Specifically, the model used employs immunocompromised nude mice bearing the LNCaP solid tumor xenograft. In vitro cytotoxicity experiments indicated that the dose causing 50% lethality for HYP in LNCaP, PC-3 and DU-145 cells were 2.07, 2.15 and 2.23 microM, respectively, following irradiation with red light (590 nm) for 30 min at a fluence rate of 0.1 J/cm2/s. Cells treated with HYP in the absence of photoirradiation showed no signs of cytotoxicity. A tissue distribution study was also carried out using the LNCaP solid tumor model to determine whether or not HYP is distributed to the target tissue. HYP was broadly distributed in tissues studied, including LNCaP tumor xenograft tissue. Furthermore, tumor tissue eliminated HYP at a slower rate than any of the other tissues examined. Interestingly, HYP levels were maintained in serum 24 h after oral administration (5 mg/kg dose). A pilot study designed to examine the efficacy of HYP treatment in nude mice bearing LNCaP tumors conducted over 28 days suggested that HYP, in combination with photoirradiation, inhibits both tumor growth and the elevation of prostate-specific antigen levels. Although the results reported for the current studies are preliminary they do provide evidence for an application of HYP PDT to prostate cancer which warrants further investigation.

Seasonal variation in hypericin content of Hypericum perforatum L. (St. John's Wort)

Hypericin and pseudohypericin, bioactive constituents in St. John's Wort (Hypericum perforatum), have been determined in the soft tops of the plant that are most likely to be browsed by foraging livestock. In two consecutive seasons, the hypericin/pseudohypericin concentration in a broad leaf biotype varied from a winter minimum of less than 100 ppm to a summer maximum approaching 3000 ppm. In contrast the narrow leaf biotype increased from similar winter values to summer maxima approaching 5000 ppm. The latter biotype was slower in returning to low levels of hypericin/pseudohypericin.

Liquid chromatography/atmospheric pressure chemical ionization mass spectrometry of terpene lactones in plasma of volunteers dosed with Ginkgo biloba L. extracts

Liquid chromatography/atmospheric pressure chemical ionization mass spectrometry (LC/APCI-ITMS) was applied to evaluate the levels of ginkgolides A and B and bilobalide in plasma of volunteers after administration of Ginkgo biloba extracts in free (Ginkgoselect) or phospholipid complex (Ginkgoselect Phytosome) forms, providing 9.6 mg of total terpene lactones. The maximum plasma concentrations, C(max), of total ginkgolides A, B and bilobalide were 85.0 and 181.8 microg/mL for Ginkgoselect and Ginkgoselect Phytosome, respectively. The C(max) values were reached at 120 min for the free form and at 180--240 min for the phospholipid complex form. In both cases, the mean elimination half-life of each terpene lactone was in the range 120--180 min. Due to its sensitivity (about 1 ng/mL) and specificity, LC/APCI-ITMS proved to be a very powerful tool for pharmacokinetic studies of these phytochemicals.