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At least 991 records · Page 55Linked to original sources
PubMed2002

Rapid quantification of constituents in St. John's wort extracts by NIR spectroscopy.

A quantitative near-infrared reflectance spectroscopy (NIRS) method was established for the determination of two major constituents (hyperforin and I3,II8-biapigenin) in St. John's wort extracts. Hyperforin was chosen due to the fact that it is found in a concentration range from 1 to 5%, a common one for NIRS determinations. I3,II8-Biapigenin on the other hand was selected as a constituent with very low concentrations (0.1-0.7%) but an extensive chromophore that allows very precise measurements in the ultraviolet (UV) and thus exact reference values that are vital for proper NIRS calibrations. Reference measurements were performed by reversed-phase high performance liquid chromatography (HPLC), determining the constituents' content in 35 pharmaceutical dry extracts of different origins. The reference method was validated according to the ICH guideline Q2B. Using partial-least squares (PLS) regression a multivariate calibration was done for the two ingredients each (PLS1). Satisfactory calibration statistics were obtained for hyperforin with a root mean square error of calibration (RMSEC) of 0.17 and a root mean square error of prediction (RMSEP) of 0.22 at a concentration range from 1 to 6% in the dry extracts. Due to the very low concentrations of I3,II8-biapigenin the accuracy of prediction is somewhat lower. However, it is possible to obtain very good results and reliable prediction by dividing the concentration range at 0.35%. The study emphasizes the potential of NIRS as a rapid and highly effective alternative method to conventional quantitative analysis of plant extracts.

Apigenin↗
PubMed2003

Disposable electrochemical sensor for rapid determination of heavy metals in herbal drugs.

Analysis of herbal drugs and extracts need rapid and affordable methods to assure the quality of products. The application of the electrochemical sensors in the field of quality control of herbal drugs, herbal drug preparations and herbal medicinal products appears very promising, advantageous and alternative to conventional methods due to their inherent specificity, simplicity and for the fast response obtained. This paper presents a proposal about the application of disposable electrochemical sensors associated with electroanalytical instrumentation for the detection of heavy metal analysis in herbal drugs. In particular samples of St. John's wort were analysed applying anodic stripping voltammetry. The content of Cd and Pb were evaluated. The ICP spectroscopy was used as reference method.

Electrochemistry↗
PubMed2003

Development of a high-performance-liquid-chromatographic method for the determination of biapigenin in biorelevant media.

A new precise, rapid and selective high-performance-liquid-chromatographic (HPLC) method has been developed to quantify biapigenin in St. John's Wort (SJW) preparations and to investigate its release characteristics in the dissolution test using both compendial and biorelevant media. Experiments were carried out on a LiChroCart 125-4, RP-18 (5 microm) column, using gradient elution at a flow rate of 1 ml/min. The binary mobile phase consisted of solvent A (acetic acid, 5:100, w:w) and B (a mixture of acetonitrile and methanol (3:1, v:v)). Detection was performed at a wavelength of 270 nm using a photodiodearray detector. The limit of detection was 0.05 microg/ml, the injection volume 20 microl. Five SJW preparations were chosen to determine the amount of biapigenin in the dosage form and to investigate their release characteristics. Best results in terms of release as well as discriminating the tested products were obtained, using fed state simulated intestinal fluid (FeSSIF), where over 80% of biapigenin was dissolved after 20 min comparing to 70% using simulated gastric fluid sine pepsin (SGF(sp)) as compendial medium. Experiments in fasted state simulated intestinal fluid (FaSSIF) show 80% release of biapigenin within 80 min.

Apigenin↗
PubMed2001

Complementary and alternative therapies for advanced prostate cancer.

This article reviews complementary and alternative therapies for advanced prostate cancer. This is not a comprehensive survey of nontraditional therapies for prostate cancer. Rather, this review focuses on alternative and complementary therapies with published studies to evaluate efficacy and safety. Three areas are addressed: alternative forms of hormonal therapy, management of side effects of hormonal therapy, and management of skeletal complications.

Acupuncture↗
PubMed2000

Inhibition of synaptosomal uptake of 3H-L-glutamate and 3H-GABA by hyperforin, a major constituent of St. John's Wort: the role of amiloride sensitive sodium conductive pathways.

Extracts of St. John's Wort are widely used for the treatment of depressive disorders. The active principles have not yet been finally elucidated. We have recently shown that hyperforin, a major active constituent of St. John's Wort, not only inhibits the neuronal uptake of serotonin, norepinephrine and dopamine, but also that of L-glutamate and GABA. No other antidepressant compound exhibits a similar broad uptake inhibiting profile. To investigate this unique kind of property, kinetic analyses were performed regarding the uptake of 3H-L-glutamate and 3H-GABA into synaptosomal preparations of mouse brain. Michaelis-Menten kinetics revealed a reduction of Vmax (8.27 to 1.80 pmol/mg/min for 3H-L-glutamate, 2.76 to 0.77 pmol/mg/min for 3H-GABA) while Km was nearly unchanged in both cases, suggesting non-competitive inhibition. The unselective uptake inhibition by hyperforin could be mimicked by the Na+-ionophore monensin and by the Na+-K+-ATPase inhibitor ouabain. However, both mechanisms can be discarded for hyperforin. Several amiloride derivatives known to affect sodium conductance significantly enhance 3H-GABA and 3H-L-glutamate uptake and inhibit the uptake inhibition by hyperforin, while monensin or ouabain inhibition were not influenced. Selective concentrations of benzamil for amiloride sensitive Na+-channels and selective concentrations of 5'-ethylisopropylamiloride (EIPA) for the Na+-H+-exchangers both had an attenuating effect on the hyperforin inhibition of L-glutamate uptake, suggesting a possible role of amiloride sensitive Na+-channels and Na+-H+-exchangers in the mechanism of action of hyperforin.

Animals↗
PubMed2001

Effects of standardized extracts of St. John's wort on the single-unit activity of serotonergic dorsal Raphe neurons in awake cats: comparisons with fluoxetine and sertraline.

St. John's wort is widely used as an herbal remedy for depression. Although its mechanism of action remains unknown, some evidence suggests that St. John's wort might act via brain serotonin (e.g., as a serotonin reuptake inhibitor). To determine whether St. John's wort affects the central serotonergic system, we monitored the discharge rate of serotonin-containing neurons in the dorsal raphe nucleus of awake cats following systemic administration of two clinical preparations of St. John's wort, Jarsin 300 (15-600 mg/kg, p.o.) and Hyperforat (0.5-4.0 ml, i.v.). Both preparations were found to have no effect on neuronal activity. This contrasts sharply with the action of fluoxetine and sertraline (2 mg/kg, p.o.), two selective serotonin reuptake inhibitors (SSRIs), which markedly depressed neuronal activity by increasing the synaptic availability of serotonin at inhibitory somatodendritic 5-HT(1A) autoreceptors. The failure of St. John's wort to depress neuronal activity cannot be attributed to an impairment of the 5-HT(1A) autoreceptor mechanism, since pretreatment with Jarsin 300 (300 mg/kg, p.o.) did not alter the responsiveness of serotonergic neurons to the 5-HT(1A) agonist 8-hydroxy-2-(di-n-propylamino)tetralin (8-OH-DPAT) (10 microg/kg, i.v.). Overall, these findings indicate that the mode of action of St. John's wort is different from that of conventional antidepressant drugs, which elevate brain serotonin and evoke negative feedback control of serotonergic neurons.

8-Hydroxy-2-(di-n-propylamino)tetralin↗
PubMed2003

Current St John's wort research from mode of action to clinical efficacy.

Preparations from St. John's wort extracts are used in the treatment of depression in many countries and represent an accepted alternative to synthetic antidepressants or behavioural therapy. St. John's wort extracts are therefore used in a therapeutic area which extends well beyond the traditional field of herbal medicine. The current status of preclinical and clinical research is summarised. St. John's wort extract has a clear inhibitory effect on the neuronal uptake not only of serotonin, noradrenaline, and dopamine but also of gamma-aminobutyric acid (GABA) and L-glutamate. No other antidepressant shows an approximately equally broad inhibitory profile. In good agreement with the effects in various biochemical models of antidepressant action, many effects in a number of behavioural pharmacology models of antidepressant efficacy could also be demonstrated for St. John's wort extract. Similar doses of John's wort also cause changes in the above-mentioned neurotransmitter systems in the brain. Out of all individual substances of St. John's wort only hyperforin and its structural analogue adhyperforin inhibit the re-uptake of the investigated neurotransmitters. However, hyperforin does not act as a competitive inhibitor at the transmitter binding sites of the transporter proteins but it affects the sodium gradient which then leads to an inhibition of uptake. The broad spectrum of action which characterises St. John's wort extracts has only been described for the pure substance hyperforin. Over the past year a number of good clinical studies have been carried out which confirm the efficacy and tolerability of St. John's wort extracts in mild depressive disorders, even if the therapeutic efficacy has recently been questioned by an American study. All studies have confirmed the good tolerability of St. John's wort extract and the very low frequency of adverse events. However, some drug interactions have been found to occur with St. John's wort extract, a number of which are of clinical relevance. In summary, pharmacological activity and therapeutic efficacy of St. John's wort extract as an antidepressant are supported by a large number of scientific publications. Within the wide range of components in St. John's wort extract, hyperforin plays an important, if not an outstanding role.

Animals↗
PubMedDate not supplied

Comparison of German St. John's wort products according to hyperforin and total hypericin content.

OBJECTIVES: To compare the hyperforin and hypericin content of currently available St. John's wort products and to determine their batch-to-batch reproducibility. DESIGN: Representative products were obtained either directly from the manufacturer or purchased from pharmacies in and around Frankfurt, Germany. For five batches from each of the eight manufacturers, 10 individual dosage forms (tablets or capsules) were analyzed for both hyperforin and hypericin content. SETTING: Laboratories of the Institute of Pharmaceutical Chemistry at Johann Wolfgang Goethe University, Frankfurt, Germany. PRODUCTS: Eight German St. John's wort products containing from 250 mg to 612 mg dry extract were studied. Three of these products are capsules, four are film-coated tablets, and one is a sugar-coated tablet. Two of the products (Jarsin 300 and Neuroplant 300) are also available in the United States. METHODS: Hyperforin concentrations were analyzed by high-performance liquid chromatography. Total hypericin concentrations were determined by polarography, an electrochemical method. Concentrations were compared among different batches of the same product and among products from different manufacturers. RESULTS: The products contained widely differing amounts of hypericin and hyperforin, even after correcting for differences in the amount of extract per dose. Some products demonstrated consistent concentrations of hyperforin and hypericin from batch to batch, others exhibited pronounced interbatch variability. CONCLUSION: The St. John's wort preparations studied exhibited large differences in hypericin and hyperforin content and are not interchangeable for the treatment of mild-to-moderate depression. Pharmacists should take this variability into account when counseling patients on the use of St. John's wort products.

Anti-Bacterial Agents↗
PubMed2002

Simultaneous determination of hypericin and hyperforin in human plasma and serum using liquid-liquid extraction, high-performance liquid chromatography and liquid chromatography-tandem mass spectrometry.

A method for the simultaneous extraction of hypericin and hyperforin from a St. John's Wort extract, which is used in case of moderate depressions and skin injuries, from human plasma and serum by liquid-liquid extraction (LLE) with n-hexane-ethylacetate (70:30, w/w) was developed. A reversed-phase high-performance liquid chromatographic (RP-HPLC) method with UV, fluorescence (FLD) and mass spectrometric (MS) detection using electrospray ionization (ESI) was used to identify and quantify hypericin and hyperforin in the extracts from blood samples. Linearity was obtained in the ranges 8.4-28.7 ng/ml (hypericin) and 21.6-242.6 ng/ml (hyperforin). Recoveries were between 32.2 and 35.6% for hypericin and 100.1 and 89.9% for hyperforin. Intra-day accuracy and precision for this method ranged between 3.2 and 4.3% and 2.6 and 2.8%, respectively. After validation of the LLE, the method was tested on real plasma samples which were obtained by ingestion of St. John's Wort extract capsules. Blood samples were taken 2, 4, and 6 h after ingestion. Finally, this method proved to be highly suitable for clinical and pharmacologically relevant studies.

Anthracenes↗
PubMed2003

2.1 A crystal structure of human PXR in complex with the St. John's wort compound hyperforin.

The nuclear xenobiotic receptor PXR is activated by a wide variety of clinically used drugs and serves as a master regulator of drug metabolism and excretion gene expression in mammals. St. John's wort is used widely in Europe and the United States to treat depression. This unregulated herbal remedy leads to dangerous drug-drug interactions, however, in patients taking oral contraceptives, antivirals, or immunosuppressants. Such interactions are caused by the activation of the human PXR by hyperforin, the psychoactive agent in St. John's wort. In this study, we show that hyperforin induces the expression of numerous drug metabolism and excretion genes in primary human hepatocytes. We present the 2.1 A crystal structure of hyperforin in complex with the ligand binding domain of human PXR. Hyperforin induces conformational changes in PXR's ligand binding pocket relative to structures of human PXR elucidated previously and increases the size of the pocket by 250 A(3). We find that the mutation of individual aromatic residues within the ligand binding cavity changes PXR's response to particular ligands. Taken together, these results demonstrate that PXR employs structural flexibility to expand the chemical space it samples and that the mutation of specific residues within the ligand binding pocket of PXR tunes the receptor's response to ligands.

Animals↗
PubMed2001

Analysis of plant complex matrices by use of nuclear magnetic resonance spectroscopy: St. John's wort extract.

The efficiency of two-dimensional homonuclear (1)H--(1)H correlated spectroscopy and two-dimensional reverse heteronuclear shift correlation spectroscopy (i.e., heteronuclear multiple quantum correlation) in characterizing and evaluating the relative content of herbal extract constituents is demonstrated. These experiments are able to fully assign the proton and carbon resonances of all three classes of constituents present in dried commercial extract of St. John's wort, that is, flavonols, phloroglucinols, and naphthodianthrones, with particular regard to the very unstable phloroglucinols. In addition, shikimic and chlorogenic acids, sucrose, lipids, polyphenols, and traces of solvents of the extractive process (methanol) were also identified. These experiments can be considered to be a very simple and fast analytical method for determining the quality and stability of the titled commercial extract. They represent a generally applicable technique for a rapid screening and a specific measurement of other commercial phytochemicals or, in selected cases, an alternative to the classical analytical techniques such as high-performance thin-layer chromatography, high-performance liquid chromatography, capillary gas chromatography, and electrophoresis.

Drug Stability↗
PubMed2004

Modulation of chemoselectivity by protein additives. Remarkable effects in the oxidation of hyperforin.

Protein additives have a dramatic effect on the H(2)O(2) oxidation of hyperforin, either protecting the enolized phloroglucinol core from oxidation (human albumin) or promoting (HRP and ovalbumin) reaction pathways derived from the intermediacy of the enollactone 4, a minor component of the oxidation mixture in the absence of protein additives. To rationalize the exquisite specificity of several steps and their mechanistic oddity, an organocatalytic effect is postulated. The use of protein additives allows a straightforward and multigram preparation of the enollactone 6, an interesting multifunctionalized scaffold for bioactivity induction and/or modulation.

Bridged Bicyclo Compounds↗
PubMed2002

Synthesis and biological evaluation of hyperforin analogues. Part I. Modification of the enolized cyclohexanedione moiety.

Modification of the St. John's wort acylphloroglucinol constituent, hyperforin (1), by acylation, alkylation, and oxidation resulted in detrimental effects on the inhibition of the synaptosomal accumulation of serotonin, showing the existence of definite structure-activity relationships in this in vitro test system and highlighting the role of the enolized cyclohexanedione moiety for activity on neurotransmitter reuptake.

Animals↗