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At least 127 records · Page 7Linked to original sources
PubMed2004

Hypericum perforatum L (St John's wort) preferentially increases extracellular dopamine levels in the rat prefrontal cortex.

The effects of hydro-alcoholic extracts of Hypericum perforatum L on extracellular serotonin (5-HT), noradrenaline (NA) and dopamine (DA) levels and the acidic metabolites (3,4-dihydroxyphenylacetic acid (DOPAC), homovanillic acid (HVA) and 5-hydroxy-3-indoleacetic acid (5-HIAA)) were examined by in vivo microdialysis in the prefrontal cortex of awake rats. Thus, a single dose (60 mg kg(-1) i.p. or 300 mg kg(-1) p.o.) of H. perforatum increased DA concentrations to 165 and 140% of control values, respectively, and increased locomotor activity in nonhabituated rats. DOPAC and HVA levels were markedly reduced. 5-HT concentrations were elevated only moderately, while the NA levels were not affected by any treatment. The whole-tissue analysis revealed that hypericum increased, whereas the monoamine oxidase (MAO) A/B inhibitor phenelzine decreased DA and 5-HT turnover. The present data indicate that the mechanism of action of hypericum extract in vivo is more complex than the inhibition of monoamine reuptake or metabolism observed in vitro. The finding of preferential enhancement of DA transmission is in agreement with human studies measuring DA-mediated neuroendocrine responses.

Animals↗
PubMed2001

Comparative evaluation of Melissa officinalis L., Tilia europaea L., Passiflora edulis Sims. and Hypericum perforatum L. in the elevated plus maze anxiety test.

There are numerous plants that have been used for their 'tranquillising' properties in Portuguese folk medicine. This report will describe a comparative analysis of the effects of Melissa officinalis L., Tilia europaea L., Passiflora edulis Sims. and Hypericum perforatum L. on the performance of mice in the elevated plus maze, open-field, and horizontal-wire tests. We have tested lyophilised aqueous extracts with doses ranging from 5-100 mg/kg prepared according to traditional folk medicine. The results indicate that Hypericum perforatum L. and Tilia europaea L. induced significant raise in immobility time, diminution of rearing and other parameters, suggesting a clear sedative effect at doses ranging from 10-100 mg/kg. Below these doses, Tilia europaea L. did not induce any significant change in the tests mentioned, while Hypericum perforatum L. (5 mg/kg) increased the time spent in the open areas of the elevated plus maze and the percentage of unprotected head-dips and stretch-approach postures, thus indicating an anxiolytic effect. For this dose, there were no significant changes in motor activity as measured by classical parameters for the tests used. As the infused H. perforatum L. tested was devoid of hyperforin, it can be stated that the observed effects cannot be attributed to this substance.

Animals↗
PubMed2001

Modulation of ion channels in rat neurons by the constituents of Hypericum perforatum.

Despite almost forty years of widespread use of antidepressant drugs, their mode of action is still unknown. Hyperforin, a phloroglucinol derivative, is a major pharmacologically and therapeutically active constituent of Hypericum perforatum extract that is widely used as an herbal antidepressant drug. However, the mechanism or mechanisms of action of these naturally abundant, non-toxic extracts remain unclear. Enzymatically isolated patch-clamped rat central and peripheral neurons exposed to rapid changes in the composition of external medium (concentration clamp) were used in our experiments to investigate the modulation of the various voltage- and ligand-gated channels by hyperforin, as well as by other constituents of Hypericum perforatum. At nanomolar concentrations, hyperforin induced significant inhibition of various ion channels. In the case of P-type Ca2+ channels, we established that hyperforin acts via interaction with calmodulin or through calmodulin-activated pathways involving at least one second messenger. The results presented here indicate that multiple mechanisms and extract constituents may be involved in the antidepressant action of Hypericum extracts, and that they could also possess neuroprotective and analgesic effects.

Animals↗
PubMed2001

Effects of Hypericum perforatum L. on evoked potentials in guinea pig hippocampal slices.

Therapeutic uses of Hypericum extracts have been demonstrated as safe and effective in treating mild to moderate depression in numerous clinical trials. To date, however, no definitive statements on their mode of action can be made, and little information on their electrophysiological effects is available. The present communication summarises the results of our efforts directed towards clarifying the effects of an ethanolic Hypericum extract (HYP) and its hydrosoluble fraction (HYPWS), and two of its constituents hypericin and hyperforin on electrically evoked population spikes in guinea pig hippocampal slices. In higher concentrations (>10 microM), the two extract constituents tested revealed inhibitory effects only, whereas concentration-dependent (between 10(-6) to 10(-4) g/l) excitatory effects were observed for HYP and HYPWS. The excitatory effects were strongly amplified by the GABA(B) antagonist phaclofen, whereas the effects of bicucullin, a GABA(A) antagonist, were marginal. The excitations were completely blocked by the AMPA antagonist CNQX, but not by the NMDA antagonists APV and MK801 or the L-type calcium-channel blocker verapamil. This kind of excitatory effect on the hippocampus is unknown in other antidepressants and; indeed, many of the latter reduce neuronal excitability. We conclude, therefore, that the mechanisms involved in the antidepressant activity of Hypericum extracts are different from those of conventional antidepressants, and that identifying their excitatory components may facilitate their more rational standardisation.

2-Amino-5-phosphonovalerate↗
PubMed2005

The lipophilic extract of Hypericum perforatum exerts significant cytotoxic activity against T24 and NBT-II urinary bladder tumor cells.

Hypericum perforatum L. (St. John's wort) is a medicinal plant used for many pathologies, especially for the treatment of mild to moderate depression. In the present study we have investigated the cytotoxic activity of the locally collected (Epirus region) Hypericum perforatum L. against cultured T24 and NBT-II bladder cancer cell lines. The lipophilic extract of the herb, prepared using petroleum ether, induced apoptosis displaying LC(50) values at concentrations as low as 4 and 5 microg/mL. A fraction of this extract displayed 60 % cell growth inhibition at a concentration of 0.95 microg/mL. Evaluating the importance of various biologically active components of the extract, it was found that hypericins (hypericin, pseudohypericin, etc.) were identified only in the methanolic (lipophobic) extract of the herb, and not in the active lipophilic extract. In addition, hyperforin concentrations in the lipophilic extract and its most active fraction, were 0.94 microg/mL, and 0.17 microg/mL, respectively, while the active cytotoxic concentration of pure hyperforin appeared in the range of 1.8 microg/mL - 5.0 microg/mL. Therefore, pure hyperforin does not seem to contribute significantly to the cytotoxicity activity. Chlorophylls were identified in low, not significantly different, concentrations in all extracts and fractions and were not correlated to the biological activity. Owing to the combination of significant cytotoxic activity, natural abundance and low toxicity, the lipophilic extract of Hypericum perforatum holds the promise of being an interesting, new, antiproliferative agent against bladder cancer that deserves further investigation.

Animals↗
PubMed1998

Hyperforin represents the neurotransmitter reuptake inhibiting constituent of hypericum extract.

Hydroalcoholic hypericum extract inhibits the synaptosomal uptake of serotonin, norepinephrine, and dopamine with about similar affinities and leads to a significant down-regulation of cortical beta-adrenoceptors and 5-HT2-receptors after subchronic treatment of rats. While neither hypericine nor kaempferol did show any reuptake inhibiting properties, hyperforin was identified as the unspecific reuptake inhibitor of hypericum extracts with half-maximal inhibitory concentrations for the three synaptosomal uptake systems mentioned above between 80 and 200 nmol/l. Moreover, a hyperforin-enriched (38%) CO2 extract also leads to a significant beta-receptor down-regulation after subchronic treatment. The data suggest hyperforin as the active principle of hypericum extracts in biochemical models of antidepressant activity.

Animals↗
PubMed1998

Activity profiles of two hyperforin-containing hypericum extracts in behavioral models.

The behavioral activity profile of a therapeutically used alcoholic hypericum extract containing hyperforin (4.5%) in rodent models was compared with that of an experimental CO2 extract devoid of hypericines but highly enriched in hyperforin (38.8%). The antidepressant activities of 50, 150 and 300 mg/ kg/day of the alcoholic extract were similar to those of 5, 15 and 30 mg/kg/day respectively of the CO2 extract. The ethanol extract in the same dose range potentiated dopaminergic behavioral responses, whereas these effects were either absent or less pronounced in the CO2 extract treated groups. By contrast, serotoninergic effects of the CO2 extract were more pronounced than those of the alcoholic extract. These and various other observations made during the study confirm that although the antidepressant action of hypericum extracts depends on their hyperforin contents, their spectrums of central activity are due to other component(s). Our working hypothesis that hyperforin and serotoninergic mechanisms are involved in the therapeutically observed antidepressant activities of hypericum extracts is in agreement with these observations.

Animals↗
PubMed1998

Effects of a methanolic extract and a hyperforin-enriched CO2 extract of St. John's Wort (Hypericum perforatum) on intracerebral field potentials in the freely moving rat (Tele-Stereo-EEG).

Two extracts of St. John's Wort (Hypericum perforatum) were investigated in the animal model "Tele-Stereo-EEG" which consisted of continuous recording of intracerebral field potentials in the freely moving rat. One was a CO2 extract for research purposes containing 30.14% hyperforin, a phloroglucine derivative known to occur within the reproductive parts of the plant, and lacking other major constituents like naphtodianthrones and flavonoids according to HPLC fingerprint. The other extract was the methanolic extract LI 160S (4.67% hyperforin). The dosage schedule was elaborated for the application of identical amounts of hyperforin in both extracts in each dosing group. Both extracts produced nearly identical patterns of electrical power changes during the first two hours of recording. These changes mainly consisted of reproducible power increases within the alpha1 band of the striatum. Comparison with earlier data obtained by identical protocols revealed that the early action was very similar to that following the application of serotonin reuptake inhibitors, thus matching biochemical in vitro data previously reported. These changes might be due to the presence of hyperforin. Only LI 160S developed a late action not seen with the CO2 extract, consisting in increases in delta activity. This late action of LI 160S matched data obtained by analysis of the action of NMDA-antagonists like MK 801 or memantine. Again, these results support previously reported biochemical findings of the interaction of hypericum extract with the glutamatergic system. In all probability, this action stems from substances only present in LI 160S, not in the CO2 extract. Which of the components contained within hypericum extracts are responsible for the clinical efficacy of St. John's wort in depression remains to be determined.

Animals↗
PubMed1998

Pharmacodynamic effects of two different hypericum extracts in healthy volunteers measured by quantitative EEG.

A double-blind, randomized, placebo-controlled parallel-group trial (phase I) was performed to evaluate the central pharmacodynamic effects of two hypericum extracts with different contents of hyperforin (0.5% and 5.0%) but identical hypericin content. Three groups of 18 volunteers between 18 and 35 years of age participated in the trial. The volunteers receiving verum took 900 mg of the extract once a day for 8 consecutive days. The primary aim of this study was to observe the frequency bands, i.e., delta (1.25-4.5 Hz), theta (4.75-6.75 Hz), alpha-1 (7.0-9.5 Hz), alpha-2 (9.75-12.5 Hz), beta-1 (12.75-18.5 Hz), and beta-2 (18.75-35 Hz). This was the first study of its kind testing hypericum controlled on the basis of its hyperforin contents. A quantitative topographic EEG (qEEG) was performed on days 1 and 8 as an indicator of drug-induced pharmacological action. The volunteers' electrophysiological data were obtained prior to application and 2, 4, 6, 8, and 10 hours post administration. Plasma samples for evaluation of the pharmacokinetics of hyperforin were also obtained. The qEEG results of the placebo group on days 1 and 8 showed no significant changes with regard to their physiological daily rhythm. In both verum groups (0.5% and 5.0% hyperforin content), reproducible central pharmacodynamic effects were apparent in comparison to placebo, in particular with the extract containing 5.0% of hyperforin. A peak pharmacodynamic efficacy was observed between 4 and 8 hours post administration. These results were confirmed on day 8 of the trial. The extract containing 5.0% hyperforin showed a marked tendency to produce higher increases in qEEG baseline power performances than the one containing 0.5% hyperforin. These higher baseline outputs on day 8 were seen at the delta, theta, and alpha-1 frequency values. Compared to placebo there was a significant increase in qEEG power performance in the delta and beta-1 frequency values exclusively for the extract containing 5.0% hyperforin. The theta and alpha-1 frequency values showed a noticeable tendency more emphasized on day 8 than on day 1. Preclinical trials in rats have been observed with similar changes in the frequency bands mentioned above, especially in the cholinergic (delta), noradrenergic (theta) and serotonergic (alpha) neurotransmitter systems. These experimental findings suggest that hypericum extracts with a high hyperforin content have a shielding effect on the central nervous system.

Adult↗
PubMed2003

Treatment with Hypericum perforatum L. does not trigger decreased resistance in Staphylococcus aureus against antibiotics and hyperforin.

Most scientific investigations of Hypericum perforatum L. (Saint John's wort) concentrated on its antidepressant activity. Only recently, its antibacterial activity against multiresistant Staphylococcus aureus led to speculations regarding the use of hyperforin, an antibacterial principle of hypericum, as an antibiotic. In the present investigation, we show that Staphylococcus aureus is able to acquire a resistance against hyperforin which did not lead to a cross resistance against clinically used antibiotics. Resistance development does not take place, however, at concentrations as low as they are found in human blood plasma during antidepressant treatment with 900 mg Hypericum extract/day.

Bridged Bicyclo Compounds↗
PubMed2001

Hypericum perforatum (St John's Wort): a non-selective reuptake inhibitor? A review of the recent advances in its pharmacology.

Hypericum possesses a unique pharmacology in that it displays the pharmacology of many classes of antidepressants and new mechanisms not typical of standard antidepressants. The most potent of all its action is the moderate to high potency for inhibition of the reuptake of monoamines, serotonin, dopamine and noradrenaline and the amino-acid neurotransmitters GABA and glutamate. Unlike standard reuptake inhibitors, hypericum exerts this reuptake inhibition non-competitively by enhancing intracellular Na+ ion concentrations. At a receptor level, chronic treatment with hypericum downregulates beta1-adrenoceptor, upregulates post-synaptic 5-HT1A receptors and 5-HT2 receptors. Although the major constituent responsible for the antidepressant effect is thought to be hyperforin, other constituents such as hypericin, pseudohypericin, flavonoids and oligomeric procyanidines may also play a direct or indirect role. While reuptake inhibition may more than likely be responsible for most of the antidepressant effect, other mechanisms may also contribute alone or in combination to exert the overall antidepressant action.

Animals↗
PubMed2005

Reduction of ethanol intake by chronic treatment with Hypericum perforatum, alone or combined with naltrexone in rats.

Acute treatment with extracts of Hypericum perforatum, the common plant usually called St. John's Wort, reduces voluntary ethanol intake in Marchigian Sardinian alcohol-preferring (msP) rats and acts synergistically with opioid receptor antagonists to further attenuate ethanol consumption. The present study evaluated the effect of chronic (once a day for 12 days) intragastric administration of a CO2 Hypericum perforatum extract (HPCO2), given alone or combined with naltrexone (NTX), on ethanol intake offered 2h/day in msP rats. Chronic treatment with HPCO2 markedly reduced ethanol intake at the dose of 125, but not at 7 mg/kg; the effect of 125 mg/kg was observed since the first day of treatment and remained constant across the 12 days. The same dose of HPCO2 slightly reduced the simultaneous intake of food only on day 3 and day 11 of treatment. Treated rats promptly recovered baseline ethanol intake when treatment did not precede access to ethanol (on day 8) or after the end of treatment (day 13 and day 14), suggesting that HPCO2 administrations did not induce conditioned aversion to alcohol. Chronic intraperitoneal treatment with NTX reduced ethanol intake at 3, but not at 0.5mg/kg. The synergistic effect on ethanol intake of HPCO2 and NTX was evident also in conditions of chronic treatment. HPCO2, 7 mg/kg, and NTX, 0.5mg/kg, evoked a pronounced and statistically significant reduction of ethanol intake, while being inactive. The effect on ethanol intake of the combined treatment remained stable over the 12 days of treatment; food intake was slightly reduced only on day 3 and on day 7 in response to 125 mg/kg of HPCO2 combined with NTX 0.5mg/kg, but no difference in body weight between controls and treated rats was observed at the end of treatment. Following 12-day treatment with 125 mg/kg of HPCO2, no difference was observed in the responsivity of msP rats to the effect on ethanol intake of several doses of the extract. In conclusion, the present results provide evidence for a selective and pronounced effect of HPCO2, alone or combined with naltrexone, on ethanol intake in conditions of chronic treatment, without development of tolerance. These findings further support the view that clinical trials for extracts of Hypericum perforatum in the treatment of alcoholism should be considered.

Administration, Oral↗
PubMed1994

Effectiveness and tolerance of the hypericum extract LI 160 compared to maprotiline: a multicenter double-blind study.

A randomized, double-blind study examining the effectiveness and tolerance of a standardized hypericum preparation when compared to maprotiline was performed in a group of 102 patients with depression, in accordance with ICD-10, F 32.1. The study was conducted in the offices of neurology and psychiatry specialists. The patients received, over a period of 4 weeks, either 3 x 300 mg of the hypericum extract or 3 x 25 mg maprotiline pills of identical appearance. Effectiveness was determined using the Hamilton Depression Scale (HAMD), the Depression Scale according to von Zerssen (D-S), and the Clinical Global Impression Scale (CGI). The total score of the HAMD scale dropped during the 4 weeks of therapy in both treatment groups by about 50%. The mean values of the D-S scale and the CGI scale showed similar results, and after 4 weeks of therapy, no significant differences in either treatment group were noticed. The onset of the effects occurred up to the second week of treatment, but were observed earlier with maprotiline than with the hypericum extract. On the other hand, maprotiline treatment resulted in more cases of tiredness, mouth dryness, and heart complaints.

Adult↗
PubMed1994

Hypericum in the treatment of seasonal affective disorders.

Seasonal affective disorder (SAD) represents a subgroup of major depression with a regular occurrence of symptoms in autumn/winter and full remission in spring/summer. Light therapy (LT) has become the standard treatment of this type of depression. Apart from this, pharmacotherapy with antidepressants also seems to provide an improvement of SAD symptoms. The aim of this controlled, single-blind study was to evaluate if hypericum, a plant extract, could be beneficial in treating SAD patients and whether the combination with LT would be additionally advantageous. Patients who fulfilled DSM-III-R criteria for major depression with seasonal pattern were randomized in a 4-week treatment study with 900 mg of hypericum per day combined with either bright (3000 lux, n = 10) or dim (< 300 lux, n = 10) light condition. Light therapy was applied for 2 hours daily. We found a significant (MANOVA, P < .001) reduction of the Hamilton Depression Scale score in both groups but no significant difference between the two groups. Our data suggest that pharmacologic treatment with hypericum may be an efficient therapy in patients with seasonal affective disorder.

Adult↗
PubMed1994

Modulation of cytokine expression by hypericum extract.

The effect of hypericum extract LI 160 on the stimulated cytokine expression was investigated in vitro in a whole blood culture system. Blood samples were taken from five healthy volunteers and four depressive patients. The release of interleukin-6 (IL-6), interleukin-1 beta (IL-1 beta) and tumor necrosis factor-alpha (TNF-alpha) was measured quantitatively after an incubation time of 24 hours on microtiter plates. A massive suppression of the interleukin-6 release was found for PHA-stimulated hypericum extract. Possible relations to the antidepressive effects of hypericum extract are discussed.

Antidepressive Agents↗
PubMed2002

In-vivo and in-vitro anti-inflammatory effect of Echinacea purpurea and Hypericum perforatum.

Echinacea purpurea (L.) Moench and Hypericum perforatum (L.) were evaluated for their anti-inflammatory activity against carrageenan-induced paw oedema in mice. Each drug was administered orally to mice at 30 and 100 mg kg(-1), twice daily. Only the higher dose significantly inhibited, time dependently, the formation of oedema, evaluated as area under the curve (echinacea P < 0.01; hypericum P < 0.05). Western blot analysis showed that in-vivo treatment with these extracts could modulate lipopolysaccharide (LPS) and interferon-gamma induced cyclooxygenase-2 (COX-2) and inducible nitric oxide synthase (iNOS) expression in peritoneal macrophages. In particular, treatment with 100 mg kg(-1) hypericum inhibited both iNOS and COX-2 expression, whereas treatment with 100 mg kg(-1) echinacea down-regulated only COX-2 expression. The present study suggests that the anti-inflammatory effect of these extracts could be in part related to their modulation of COX-2 expression.

Animals↗
PubMed2002

Long term administration of Hypericum perforatum improves spatial learning and memory in the water maze.

The aim of the present study is to investigate the effects of long-term Hypericum perforatum treatment on spatial learning and memory in rats. Hypericum preparation (HP) standardized to 0.3% hypericin content was administered orally for 9 weeks in doses of 4.3 and 13 microg/kg corresponding to therapeutic dosages in humans of 0.3 and 0.9 mg of total hypericins daily. A Morris water maze paradigm was used. The mean escape latency over 4 d for the Control group (21.9 s) and HP 4.3 group (21.7 s) was significantly greater than the latency of the HP 13 group (15.8s). In the probe trial on day 5, the HP 13 group crossed the correct annulus in the SE quadrant more often (4.5) than the other groups: Con (2.4) and HP 4.3 (3.1). After completion of the behavioral experiment, the regional brain concentrations of monoamines and metabolites were estimated in selected brain regions, i.e. prefrontal cortex, hippocampus and hypothalamus. Analysis of variance (ANOVA) demonstrated significant differences in the content of monoamines and metabolites between the treatment groups compared to the Control. The increased 5-hydroxytryptamine (5-HT) levels in the prefrontal cortex correlated positively with the retention of spatial memory. These findings show that the long-term administration of Hypericum perforatum can improve learning and spatial memory with significant changes in the content of monoamines in several brain regions.

Animals↗
PubMed2004

[Discussion on clinical efficacy of Hypericum perforatum for depression abroad].

The development of molecular pharmacology and neuropharmacology accelerated the studies on molecular mechanism of Hypericum perforatum for depression. The clinical trials indicated that this galenical was superior to the traditional synthetic drugs for antidepression. This preparation had good tolerability and safety. Clinical pharmacokinetics and pharmacodynamics provided further evidence for clinical application of Hypericum. The clinical efficacy of Hypericum for depression was notable and credible.

Clinical Trials as Topic↗