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PubMed2001

Hyperforin--antidepressant activity by a novel mechanism of action.

Hyperforin represents a major antidepressive constituent of St. John's wort (SJW) extract. It not only inhibits the neuronal uptake of serotonin, norepinephrine and dopamine like many other antidepressants, but also inhibits GABA and L-glutamate uptake. This broad-spectrum effect is obtained by an elevation of the intracellular Na+ concentration, probably due to activation of sodium conductive pathways not yet finally identified but most likely ionic channels. This makes hyperforin the first member of a new class of compounds with a preclinical antidepressant profile due to a completely novel mechanism of action.

Animals↗
PubMed2003

Methadone maintenance treatment and St. John's Wort - a case report.

St. John's wort, a popular over-the-counter drug for treatment of depression, might reduce concentrations of drugs such as cyclosporin and indinavir and lead to drug resistance and treatment failure. No studies as yet have examined its influence on methadone plasma levels. The trough methadone plasma levels were measured in four patients (2 males, median age: 31 years; range 19 - 40 years) in methadone maintenance treatment just before the introduction of St. John's wort (900 mg/d) and after a median period of 31-day treatment (range 14 - 47). The study was proposed to addict patients about to start an antidepressant therapy. Introduction of St. John's wort resulted in a strong reduction of (R,S)-methadone concentration-to-dose ratios in the four median patients included, with a median decrease to 47 % of the original concentration (range: 19 % - 60 % of the original concentration). Two patients reported symptoms that suggested a withdrawal syndrome. Thus, prescription of St. John's wort might decrease methadone blood levels and induce withdrawal symptoms which, if not correctly identified and handled (by changing the antidepressant or by increasing the methadone dose), might cause unnecessary discomfort to the patient, lead to resumption of illicit drug uses, or be a risk factor for discontinuation of the methadone or antidepressant treatment.

Adult↗
PubMed2003

Effect of acute drought stress and time of harvest on phytochemistry and dry weight of St. John's wort leaves and flowers.

The phytochemistry and dry weight of cultivated St. John's wort are significantly influenced by acute drought stress and time of harvest. In this study, plants subjected to brief drought stress during both flower and seed development periods exhibited increased concentrations in 8 of the 10 phytochemicals examined in this study, including hypericin, pseudohypericin, chlorogenic acid, rutin, hyperoside, isoquercitrin, quercitrin, and quercetin. Increases ranged from 5% to 36% (hyperoside and rutin, respectively). Conversely, the concentrations of hyperforin and adhyperforin in flowers were decreased by an average of 10% in drought-stressed plants as compared to well-watered control plants. Acute drought stress decreased flower dry weight significantly during both drydown periods, although vegetative parameters (height, leaf dry weight and stem dry weight) were not adversely affected. While acute drought stress significantly altered the chemical yield in the leaves and flowers (phytochemical content x harvested dry weight), the time of harvest was the predominant factor determining phytochemical concentration in the organs of H. perforatum.

Adaptation, Physiological↗
PubMed2004

[Meta-analysis of effectiveness and tolerability of treatment of mild to moderate depression with St. John's Wort].

After anxiety, depression is one of the most common psychiatric diseases, showing a lifetime prevalence of 4.4 - 18 %. St. John's Wort is a herbal antidepressant combining a long tradition of use with well-proven medical research. We conducted a meta-analysis to review St. John's Wort's place in the treatment of depression. A comprehensive literature search was conducted for studies comparing effectiveness and tolerability of St. John's Wort with either placebo or synthetic antidepressant. Thirty studies met the inclusion as well as the quality criteria and were included in the meta-analysis. Four studies consisted of all three arms and were thus included in both analyses. Our results demonstrated a significant advantage for St. John's Wort compared to placebo (n = 2129, RR = 0.66, 95 % CI 0.57 - 0.78, p < 0.00001, NNT = 4.2 95 % CI 3.0 - 6.6, mean response: 53.3 vs. 32.7 %). Compared to synthetic antidepressants St. John's Wort demonstrated similar effectiveness (n = 2231, RR = 0.96, 95 % CI 0.85 - 1.08, p = 0.5, mean response: 53.2 % vs. 51.3 %). In the sub-group of mild to moderate depression, corresponding with the indication for St. John's Wort assigned by the German health authority, the herbal antidepressant showed better results against the synthetic antidepressants (n = 1166, RR = 0.85, 95 % CI 0.75 - 0.97, p = 0.01, NNT = 14.3, 95 % CI 8.3 - 100, mean response 59.5 vs. 52.9 %). This result viewed together with St. John's Wort's favourable side-effects profile, leading to a lower rate of drop-outs, suggests treatment with St. John's Wort should be attempted for milder forms of depression. Funnel plot analysis suggested publication bias could exist for the comparison with placebo. To put this in a perspective the fail-safe-N-test calculated that 423 studies with no effect would be needed to negate the presented result for placebo studies.

Antidepressive Agents↗
PubMed2004

Flavonoids of St. John's Wort reduce HPA axis function in the rat.

A common biological alteration in patients with major depression is the activation of the hypothalamic-pituitary-adrenal (HPA) axis, manifested as hypersecretion of adrenocorticotropic hormone (ACTH) and cortisol. The hyperactivity of the HPA axis in depressed patients can be corrected during clinically effective therapy with standard antidepressant drugs such as imipramine, indicating that the HPA axis may be an important target for antidepressant action. We previously showed that a methanolic extract of St. John's Wort (SJW) and hypericin, one of its active constituents, both have delayed effects on the expression of genes that are involved in the regulation of the hypothalamic-pituitary-adrenal (HPA) axis , whereas the phloroglucinol derivative hyperforin was inactive in the same model . Since flavonoids of SJW are also discussed as active constituents it was of interest to determine whether these compounds can modulate HPA axis function. Imipramine (15 mg/kg), hypericin (0.2 mg/kg), hyperoside (0.6 mg/kg), isoquercitrin (0.6 mg/kg) and miquelianin (0.6 mg/kg) given daily by gavage for two weeks significantly down-regulated circulating plasma levels of ACTH and corticosterone by 40 - 70 %. However, none of the compounds tested had an effect on plasma ACTH and corticosterone levels after chronic treatment (daily gavage for 8 weeks). Our data suggest that besides hypericin, flavonoids of SJW play an important role in the modulation of HPA axis function. Furthermore, the results support the hypothesis that flavonoids are involved in the antidepressant effects of SJW.

Administration, Oral↗
PubMed2004

Behavioral pharmacology of sigma-ligands.

Sigma (sigma) receptors, first defined as a subclass of opioid receptors, later confounded with the high affinity phencyclidine (PCP) binding sites, now are regarded as unique binding sites, distinct from opiate and PCP receptors, and related to higher brain function. The investigation of functional significance of sigma receptors in the brain has been hampered for many years by relative lack of specific tool drugs and by the unavailability of their coherent classification into postulated agonists and antagonists. However, a potential involvement of sigma receptors in psychotic disorders was first suggested soon after their discovery. The sigma receptors are classified into two subtypes, sigma (1) and sigma (2) receptors, of which the first was recently cloned from rodent and human tissues while the second has not yet been fully characterized. Although the precise mechanism of the functional response of these receptors is still uncertain, it is accepted that sigma receptors can modulate a number of central neurotransmitter systems, including noradrenergic, glutamatergic and dopaminergic ones. The sigma receptors have been postulated to be involved in numerous pharmacological and physiological functions, including motor disorders, psychotic disorders, neuroprotective mechanisms. In the last years, a number of compounds with a high affinity and selectivity for sigma binding sites have been discovered and investigated for their therapeutic potential. In this review, we try to summarize the behavioral effects of sigma receptor ligands that have been described, and their activity in animal models related to some brain disorders, especially schizophrenia and affective disorders.

Amnesia↗
PubMed2004

Modulation of P-glycoprotein function by St John's wort extract and its major constituents.

INTRODUCTION: Recent data suggest some relevant drug interactions caused by St John's wort extract, which can be explained by interactions with the Cytochrome P450 system or P-Glycoprotein (Pgp). Interaction with Pgp, including activation, inhibition and induction, can lead to altered plasma or brain levels of Pgp substrates. The aim of the present study was to investigate the possible interactions of St John's wort extract and most relevant constituents with the transport activity of Pgp. METHODS: We characterized the modulatory potencies in two in vitro assays using calcein-AM, first in VLB cells (a human lymphocytic leukemia cell line expressing Pgp) and second in PBCEC cells (porcine brain capillary endothelial cells). RESULTS: The extract, as well as some of the tested constituents modulate the transport by Pgp in the micromolecular range. Quercetin and hyperforin seem to be most potent. CONCLUSIONS: These findings suggest the possibility of drug interactions at the level of the gastro-intestinal absorption of drugs. Plasma levels of the constituents of St John's wort are very likely too low to interfere with Pgp at the blood-brain-barrier with the possible exception of quercetin.

ATP Binding Cassette Transporter, Subfamily B, Mem↗
PubMed2005

No relevant interaction with alprazolam, caffeine, tolbutamide, and digoxin by treatment with a low-hyperforin St John's wort extract.

We evaluated the pharmacokinetic interaction between a low-hyperforin St John's wort (SJW) extract and alprazolam, caffeine, tolbutamide, and digoxin. Previous reports on other SJW products had shown remarkably decreased plasma concentrations of certain co-medicated drugs, which was attributed to an inducing effect of SJW on cytochrome P-450 (CYP) and p-glycoprotein (p-gp) activity. Two randomised, placebo-controlled studies were performed with 28 healthy volunteers (age 18 - 55 years) in each study. In study A, single doses of alprazolam (1 mg; substrate of CYP3A4) and caffeine (100 mg; CYP1A2) were given on days 1 and 11. In study B, single doses of tolbutamide (500 mg, days 1 and 11; CYP2C9) and multiple doses of digoxin (0.75 mg on days -2 and -1, 0.25 mg/die on days 1 to 11; p-gp) were given. The participants received SJW (Esbericum capsules; 240 mg/die of extract, 3.5 mg hyperforin) or placebo on days 2 to 11. Blood for pharmacokinetic analysis was drawn on days 1 and 11. No statistically significant differences were found in the primary kinetic parameter, AUC0 - 24, of alprazolam, caffeine (AUC0 - 12), paraxanthine, tolbutamide, 4-hydroxytolbutamide, and digoxin between the placebo group and the SJW group at the end of the study. The SJW-induced change in AUCs was less than 12 % of the initial median AUC of the participants in studies A and B, thus clinically irrelevant. On day 11, trough concentrations were 2.0 (range 0.6 - 4.1) microg/L and 1.0 (0.2 - 3.9) microg/L for hypericin and pseudohypericin, respectively, whereas hyperforin concentrations were below the quantification limit (< 1 microg/L). Kinetics of investigated probe drugs were only marginally influenced by concomitant treatment with Esbericum capsules. This may be due in particular to the low hyperforin plasma concentration as this SJW component has been shown to activate the PXR receptor which regulates expression of CYP3A4 and p-gp. Our findings corroborate the view that reports about interactions of other SJW extracts seem not to be predictive for the product we studied.

Adult↗
PubMed2006

[Acute hepatitis due to kava-kava and St John's Wort: an immune-mediated mechanism?].

HISTORY AND CLINICAL FINDINGS: In an otherwise healthy 48-year-old female patient, acute hepatitis with transaminase increase (GOT up to 613 U/l, GPT up to 752 U/l), inconspicuous hepatitis serology findings, negative autoantibody status and negative virus serology was observed after a 10-week long intake of kava-kava (1-3 x 200 mg/day) and St John's Wort (1 x 425 mg/day). Biopsy of the liver showed lobular and portal necroinflammatory activity without indication of cirrhosis. DIAGNOSIS: Due to these findings with proven T-cell activity (lymphocyte typing, neopterin determination) as well as the aetiopathology, this form of hepatitis with histological characteristics of a nutritive/medicinal toxic origin was classified as induced immunologic idiosyncratic hepatitis, possibly in terms of an antibody-negative autoimmune hepatitis. TREATMENT AND CLINICAL COURSE: Discontinuation of the existing medication and simultaneous onset of immunosuppressive combination therapy of cortisone, azathioprine and ursodeoxycholic acid resulted in normalisation of the liver parameters within a period of two months. CONCLUSION: On the one hand, it appears that simultaneous intake of St John's Wort possibly potentiates the toxicity of kavapyrones. On the other hand, an immune-mediated mechanism, induced by kava-kava, cannot be completely excluded in the present case. It must be stressed that in patients with autoimmune hepatitis, precise history of medication intake should also be available.

Alanine Transaminase↗
PubMed2006

Effects of St. John's wort extract and single constituents on stress-induced hyperthermia in mice.

Emotional or stress-induced hyperthermia (SIH) is the rise of body temperature following exposure to psychological stress and has been demonstrated across species. In the present experiments we used exposure to an open field (OF) as inescapable stressor. Exposure of male BL6/C57J mice to OF stress significantly increased body temperature (DeltaT = 1.8 +/- 0.13 degrees C, p < 0.05). SIH is calculated as the difference (DeltaT = T (2) - T (1)) between the basal temperature (T (1)) and the temperature after exposure to an OF for 10 min (T (2)). Using this experimental design, St. John's wort extract (SJW) as well as various single compounds of it were tested for their ability to affect DeltaT. Anxiolytic drugs (the benzodiazepine diazepam; 5 mg/kg, and the 5HT (1A) receptor agonist buspirone; 10 mg/kg) significantly reduced DeltaT, whereas antidepressants (imipramine and fluoxetine) had no effect on DeltaT. Oral administration of SJW extract significantly reduced DeltaT in doses of 250 and 500 mg/kg. Higher (750 and 1000 mg/kg) as well as a lower dose (125 mg/kg) did not affect DeltaT after stress, indicating a U-shaped dose-response curve. Hypericin (0.1 mg/kg, p. o.) administered 60 min prior to testing significantly decreased DeltaT (p < 0.05) whereas hyperforin (1 - 10 mg/kg, p. o.) had no effect in this test paradigm. The flavonoids hyperoside, isoquercitrin and quercitrin (all at 0.6 mg/kg, p. o.) and rutin (1 mg/kg, p. o.) only partially blocked OF-induced hyperthermia. If compared to all other flavonoids, the quercetin 3-O-glucuronide miquelianin (1.2 mg/kg, p. o.) was the most potent compound tested in this experimental design. From the biflavonoids in SJW, only amentoflavone decreased SIH-induced hyperthermia in a dosage of 0.1 mg/kg. In conclusion, using open field stress as a psychological stressor to induce hyperthermia in mice we were able to detect putative anxiolytic effects of SJW extract and single consituents.

Administration, Oral↗
PubMed2006

Vitamin E reduces antidepressant-related beta-adrenoceptor down-regulation in cultured cells. Comparable effects on St. John's wort and tricyclic antidepressant treatment.

The mode of action of antidepressants is still a matter of debate. Acute inhibition of neurotransmitter reuptake in central neuronal synapses, followed by a down-regulation of central postsynaptic beta-adrenoceptor (beta-AR) numbers were consistently observed in vivo, while a reduction in surface beta-AR density was found in cell cultures. Effects of the tricyclic antidepressant desipramine (DMI) were abolished by vitamin E (alpha-TOC) in vitro as well as in vivo. Alpha-TOC interfered with antidepressant-induced changes of cellular plasma membrane properties and with recycling of beta-AR. St. John's wort (SJW) extract reduced beta-AR numbers in cultured cells to a similar extent as DMI or the selective serotonin re-uptake inhibitor fluoxetine. We chronically co-exposed cell cultures to SJW extract and to alpha-TOC. Receptor down-regulation following exposure to the plant extract was inhibited in the presence of alpha-TOC suggesting a mode of action of SJW extract comparable to that of synthetic antidepressants. Inhibition of cell proliferation by the plant extract was also significantly reduced by alpha-TOC.

Animals↗
PubMed1997

LI 160, an extract of St. John's wort, versus amitriptyline in mildly to moderately depressed outpatients--a controlled 6-week clinical trial.

Up to now, the antidepressant efficacy of the extract of St. John's wort, LI 160, has been compared to imipramine and maprotiline, demonstrating similar antidepressant efficacy in mildly to moderately depressed patients, treated either with LI 160 or the respective synthetic comparator. In the study reported here, LI 160 (total daily dose: 900 mg) was compared with the sedating tricyclic amitriptyline (total daily dose: 75 mg) in a controlled, randomized, multicentre trial. At the end of the 6-week study, the major target variable, the Hamilton Depression Scale response rate, exhibited no statistically significant difference between the groups, although a tendency for a better response rate was seen in the amitriptyline group. The secondary efficacy parameters, decreases in the total Hamilton Depression and Montgomery-Asberg scores, showed a significant advantage for amitriptyline, but only at week 6. With regard to tolerability, LI 160 was clearly superior to amitriptyline, particularly in relation to anticholinergic and Central Nervous System adverse events. Thus, 37% of the LI 160 treated patients reported adverse events, compared to 64% in the amitriptyline group. This considerable superiority in tolerability for LI 160 in relation to amitriptyline, could confer an advantage in improving compliance for antidepressant pharmacotherapy.

Adult↗
PubMed1997

Efficacy and tolerability of St. John's wort extract LI 160 versus imipramine in patients with severe depressive episodes according to ICD-10.

The special extract of St. John's wort, LI 160, exhibited a superior antidepressant efficacy compared to placebo in several controlled trials. Two further trials demonstrated a similar reduction of depressive symptomatology under LI 160 compared to tricyclics. All these trials were performed in mildly to moderately depressed patients. The present investigation was a randomized, controlled, multicentre, 6-week trial comparing 1800 mg LI 160/die to 150 mg imipramine/die in severely depressed patients according to ICD-10. The main efficacy parameter, a reduction of the total score of the Hamilton Depression Scale, proved both treatment regimens very effective at the end of the 6 week treatment period (mean values 25.3 to 14.5 in the LI 160 group and 26.1 to 13.6 in the imipramine group), but not statistically equivalent within a a-priori defined 25% interval of deviation. The analysis of subgroups with more than a 33% and 50% reduction of the HAMD total score justified the assumption of equivalence within a 25% deviation interval. This view was also supported by the global efficacy ratings from patients and investigators. Regarding adverse events, the nonrejection of the nonequivalence hypothesis denotes a superiority of the herbal antidepressant. These main result indicate that LI 160 might be a treatment alternative to the synthetic tricyclic antidepressant imipramine in the majority of severe forms of depressions. However, more studies of this type must be performed before a stronger recommendation can be made.

Adult↗