Anxiolytic effects of fractions obtained from Passiflora incarnata L. in the elevated plus maze in mice.

The purpose of this study was to characterize the putative anxiolytic-like activity of fractions prepared from a hydroethanol extract of Passiflora incarnata L. using the elevated plus-maze (EPM) in mice. The fractions were prepared as published recently, yielding a butanol, petroleum ether and chloroform fraction. From the tested fractions, the butanol fraction showed significant increases in the number of open arm entries in the EPM in concentrations of 2.1 mg/kg and 4.2 mg/kg corresponding to 150 and 300 mg/kg of the original extract. The highest activity was found for the chloroform fraction in doses of 0.17 mg/kg (10.0 ± 1.9, p < 0.001) and 0.34 mg/kg (6.6 ± 0.86; p < 0.05) which corresponds to a total extract dose of 150 and 300 mg/kg, respectively. Interestingly, the petroleum ether fraction did not show any effects in the elevated plus maze. A sedative or stimulatory effect of each of the fractions could be excluded, since none of the compounds had an influence on the total distance that the animals covered during the observation period. The results suggest that the active principle of passion flower seems to be in the chloroform fraction and to a lower extent in the butanol fraction.

An aqueous extract of Ammi visnaga fruits and its constituents khellin and visnagin prevent cell damage caused by oxalate in renal epithelial cells.

Teas prepared from the fruits of Ammi visnaga L. (syn. "Khella") have been traditionally used in Egypt as a remedy to treat kidney stones. It was the aim of our study to evaluate the effect of a Khella extract (KE) as well as the two major constituents khellin and visnagin on renal epithelial injury using LLC-PK1 and Madin-Darby-canine kidney (MDCK) cells. Both cell lines provide suitable model systems to study cellular processes that are possibly involved in the development of a renal stone. LLC-PK1 and MDCK cell lines were exposed to 300 microM oxalate (Ox) or 133 microg/cm(2) calcium oxalate monohydrate (COM) in presence or absence of 10, 50, 100 or 200 microg/mL KE. To evaluate cell damage, cell viability was assessed by determining the release of lactate dehydrogenase (LDH). KE (e.g. 100 microg/ml) significantly decreased LDH release from LLC-PK1 (Ox: 8.46+0.76%; Ox + 100 microg/ml KE: 5.41+0.94%, p<0.001) as well as MDCK cells (Ox: 30.9+6.58%; Ox+100 microg/ml KE: 17.5+2.50%, p<0.001), which indicated a prevention of cell damage. Similar effects for KE were observed in both cell lines when COM crystals were added. In LLC-PK1 cells khellin and visnagin both decreased the % LDH release significantly in cells that were pretreated with Ox or COM crystals. However, khellin and visnagin exhibited different responses in MDCK cells. Whereas khellin slightly reduced the % LDH release after exposure of the cells to Ox and COM crystals, visnagin significantly decreased % LDH release only after COM crystal exposure. Overall both compounds were more active in LLC-PK1 than in MDCK cells. In summary, exposure of renal epithelial cells to Ox or COM crystals was associated with a significant release of LDH indicating cell injury. Our data demonstrate that KE as well as khellin and visnagin could prevent renal epithelial cell damage caused by Ox and COM and could therefore play a potential role in the prevention of stone formation associated with hyperoxaluria.

Mechanism of St. John's wort extract (STW3-VI) during chronic restraint stress is mediated by the interrelationship of the immune, oxidative defense, and neuroendocrine system.

Chronic stress is a contributing risk factor for the development of psychiatric illnesses such as anxiety and depression disorders. The aim of the present study was to evaluate the mechanisms of action of the standardized St. John's wort extract (STW3-VI; SJW) in a chronic restraint stress model. Markers of antioxidant capacity such as superoxide dismutase (SOD), glutathione peroxidase (GPx), and catalase (CAT) in the hippocampus and hypothalamus, and plasma levels of ACTH and corticosterone as well as the inflammatory markers IL-6 and TNF-alpha were determined in rats exposed to chronic restraint stress for 21 consecutive days. In addition, total body and relative organ weights as well as behavioral changes in the open field test were evaluated on the last day. The results show that stressed animals decreased in open field activity compared to unstressed animals, which could be reversed by fluoxetine (10mg/kg, p.o.) and SJW (125-750mg/kg, p.o.) treatment. In addition, chronic restraint stress significantly decreased thymus and spleen indices in the stressed control group. However, treating stressed rats with fluoxetine or STW3-VI produced a significant and dose dependent increase in both thymus and spleen indices compared to stressed controls. Additionally, SJW and fluoxetine significantly reduced stress-induced increases in plasma ACTH and corticosterone levels. Furthermore, the administration of SJW significantly reduced the stress-induced increase in TNF-alpha levels. Our data provide new evidence for the hypothesis that the mechanism of action of STW3-VI is mediated by the interrelationship between the immune, oxidative defense and neuroendocrine system.

Anxiolytic effects of a passion flower (Passiflora incarnata L.) extract in the elevated plus maze in mice.

The purpose of this study was to characterize the putative anxiolytic-like activity of an ethanolic extract prepared from passion flower (PF) (Passiflora incarnata L.) using the elevated plus maze (EPM) in mice. The mice were either treated orally with three different concentrations of the PF extract or the positive control diazepam. The number of entries in the open arms was significantly increased after administration of diazepam compared to the control. PF extract showed a significant increase in number of open arm entries at a concentration of 375 mg/kg, whereas no activity was observed in 150 and 600 mg/kg, respectively, indicating an U-shaped dose response curve. In conclusion, using the EPM we were able to detect putative anxiolytic effects of a Passiflora incarnata extract in mice.

Grapefruit-drug interactions: can interactions with drugs be avoided?

Grapefruit is rich in flavonoids, which have been demonstrated to have a preventive influence on many chronic diseases, such as cancer and cardiovascular disease. However, since the early 1990s, the potential health benefits of grapefruit have been overshadowed by the possible risk of interactions between drugs and grapefruit and grapefruit juice. Several drugs interacting with grapefruit are known in different drug classes, such as HMG-CoA reductase inhibitors, calcium antagonists, and immunosuppressives. Currently known mechanisms of interaction include the inhibition of cytochrome P450 as a major mechanism, but potential interactions with P-glycoprotein and organic anion transporters have also been reported. This review is designed to provide a comprehensive summary of underlying mechanisms of interaction and human clinical trials performed in the area of grapefruit drug interactions and to point out possible replacements for drugs with a high potential for interactions.

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.

Extracts of St. John's wort and various constituents affect beta-adrenergic binding in rat frontal cortex.

The present study was designed to get further insight into the mode of antidepressant action of extracts prepared from St. John's wort (SJW) and relevant active constituents. Down-regulation of central beta-adrenergic receptors (beta-AR's) has been widely considered a common biochemical marker of antidepressant efficacy. Although previous studies have reported a beta-AR down-regulation for SJW extracts, in vivo studies that compare the effects of SJW extracts with those of relevant active constituents on beta-AR density have not been done yet. We used quantitative radioligand receptor-binding-studies to examine in rats the effects of short-term (2 wks) and long-term (8 wks) administration of different SJW extracts and constituents on beta-AR binding in rat frontal cortex. The effects were compared to those of the standard antidepressants imipramine and fluoxetine. [125I]CYP binding to beta-AR was found to be decreased after short as well as after long-term treatment with imipramine (36%, 40%). Short-term treatment with fluoxetine decreased the number of beta-adrenergic receptors (17%) while long-term treatment with fluoxetine elicited an increase (14%) in beta-AR-binding. This effect was comparable to that of the lipophilic CO2 extract which decreased beta-AR-binding (13%) after two weeks and slightly increased the number of beta-AR's after 8 weeks (9%). Short-term treatment with the methanolic SJW extract decreased beta-AR-binding (14%), no effects for this extract were observed after 8 weeks. Treatment with hypericin led to a significant down-regulation (13%) of beta-AR's in the frontal cortex after 8-weeks, but not after 2 weeks, while hyperforin (used as trimethoxybenzoate, TMB), and hyperoside were ineffective in both treatment paradigms. Compared to the SJW extracts and single compounds the effect of imipramine on beta-AR-binding was more pronounced in both treatment paradigms.

Plasma levels of hypericin in presence of procyanidin B2 and hyperoside: a pharmacokinetic study in rats.

The biological evaluation of hypericin in various test models is hampered by its poor water solubility. In former studies we have shown that the water solubility of hypericin was remarkably enhanced in the presence of the procyanidins or flavonol glycosides of Hypericum extract. The present pharmacokinetic study was designed to find out whether the improved water solubility in the presence of procyanidin B2 or hyperoside is correlated to increased plasma levels of hypericin. Plasma levels of hypericin in rats in the presence and absence of procyanidin B2 or hyperoside were determined by reversed phase HPLC using fluorimetric detection. Both compounds increased the oral bioavailability of hypericin by ca. 58 % (B2) and 34 % (hyperoside). Procyanidin B2 and hyperoside had a different influence on the plasma kinetics of hypericin; median maximal plasma levels of hypericin were detected after 360 min (C max : 8.6 ng/mL) for B2, and after 150 min (C max : 8.8 ng/mL) for hyperoside. It can be speculated that, when administered together with these compounds, a significant accumulation of hypericin in rat plasma in the presence of both polyphenols might be responsible for the observed increased in vivo activity.

[Pharmacologic and clinical studies using Cimicifuga racemosa in climacteric complaints]. / Pharmakologische und klinische Untersuchungen zum Einsatz von Cimicifuga racemosa bei klimakterischen Beschwerden.

Climacteric complaints are caused by a decrease in estrogen production and are characterized by neurovegetative and psychic complaints. Hot flushes represent the leading symptom, in addition excitability, irritability and sleep disturbances are reported. These complaints are usually treated with estrogens, but extracts of Cimicifuga racemosa are used for this indication, too. Clinical studies gave evidence for the efficacy of Cimicifuga extracts in patients with climacteric symptoms. In pharmacological experiments Cimicifuga extracts exhibited organ specific estrogenic effects and were characterised as selective estrogen-receptor-modulators. In addition pronounced effects on the central nervous system were shown. Taking these relevant therapeutic properties into account further experimental and clinical studies seem to be necessary and promising.

St John's wort, hypericin, and imipramine: a comparative analysis of mRNA levels in brain areas involved in HPA axis control following short-term and long-term administration in normal and stressed rats.

Clinical studies demonstrate that the antidepressant efficacy of St John's wort (Hypericum) is comparable to that of tricyclic antidepressants such as imipramine. Onset of efficacy of these drugs occurs after several weeks of treatment. Therefore, we used in situhybridization histochemistry to examine in rats the effects of short-term (2 weeks) and long-term (8 weeks) administration of imipramine, Hypericum extract, and hypericin (an active constituent of St John's wort) on the expression of genes that may be involved in the regulation of the hypothalamic-pituitary-adrenal (HPA) axis. Imipramine (15 mg kg(-1)), Hypericum (500 mg kg(-1)), and hypericin (0.2 mg kg(-1)) given daily by gavage for 8 weeks but not for 2 weeks significantly decreased levels of corticotropin-releasing hormone (CRH) mRNA by 16-22% in the hypothalamic paraventricular nucleus (PVN) and serotonin 5-HT(1A) receptor mRNA by 11-17% in the hippocampus. Only imipramine decreased tyrosine hydroxylase (TH) mRNA levels in the locus coeruleus (by 23%), and only at 8 weeks. The similar delayed effects of the three compounds on gene transcription suggests a shared action on the centers that control HPA axis activity. A second study was performed to assess the effects of long-term imipramine and Hypericum administration on stress-induced changes in gene transcription in stress-responsive circuits. Repeated immobilization stress (2 h daily for 7 days) increased mRNA levels of CRH in the PVN, proopiomelanocortin (POMC) in the anterior pituitary, glutamic acid decarboxylase (GAD 65/67) in the bed nucleus of the stria terminalis (BST), cyclic AMP response element binding protein (CREB) in the hippocampus, and TH in the locus coeruleus. It decreased mRNA levels of 5-HT(1A) and brain-derived neurotrophic factor (BDNF) in the hippocampus. Long-term pre-treatment with either imipramine or Hypericum reduced to control levels the stress-induced increases in gene transcription of GAD in the BST, CREB in the hippocampus, and POMC in the pituitary. The stress-induced increases in mRNA levels of CRH in the PVN and TH in the locus coeruleus were reduced by imipramine but not by Hypericum. The stress-induced decreases in BDNF and 5-HT(1A)mRNA levels were not prevented by either drug. Taken together, these data show: (1) that Hypericum and hypericin have delayed effects on HPA axis control centers similar to those of imipramine; and (2) that select stress-induced changes in gene transcription in particular brain areas can be prevented by long-term treatment with either the prototypic tricyclic antidepressant imipramine or the herbiceutical St John's wort. However, imipramine appears to be more effective in blocking stress effects on the HPA axis than the plant extract.

Pharmacological and endocrine effects of Hypericum perforatum and hypericin after repeated treatment.

Clinical studies have demonstrated the antidepressant efficacy of Hypericum (St. John's wort) extracts comparable to tricyclic antidepressants such as imipramine. We examined the effects of Hypericum extract and hypericin, one active constituent, in the forced swimming test (FST) after treatment repeated for 14 days. It has recently been shown that hypericin was inactive in the FST after acute treatment, but remarkably active when solubilized by subfraction IIIc1 containing mainly procyanidin B2. Therefore, we investigated the cooperative effects of hypericin and procyanidin B2 after repeated treatment. Imipramine (15 mg/kg), Hypericum extract (500 mg/kg) and hypericin (0.1 mg/kg) given daily for 2 weeks significantly reduced immobility time in the FST. No differences were observed between animals receiving pure hypericin and those receiving hypericin in combination with procyanidin B2. As several antidepressants act on the neuroendocrine axis resulting in altered hormone concentrations, selected endocrine parameters were investigated after repeated treatment. Daily treatment with either imipramine, Hypericum extract or hypericin alone or in combination with procyanidin B2 for 14 days significantly decreased plasma ACTH and corticosterone levels. None of the substances had pronounced effects on plasma prolactin or LH levels. From our present data, we propose that cooperative effects of hypericin and procyanidin B2 are of important relevance for the acute, but not for the chronic effects of this polycylic quinone.

Antidepressant effects of apocynum venetum leaves in a forced swimming test.

An extract of the leaves of Apocynum venetum L. (Apocynaceae) markedly shortened the immobility time of male rats in a forced swimming test (FST) in a dose range of 30-125 mg/kg, indicating a possible antidepressant activity. This effect was comparable to that of the tricyclic antidepressant imipramine (20 mg/kg). Neither imipramine (20 mg/kg) nor the Apocynum extract in various doses (30, 60, 125 mg/kg) produced any overt behavioural change or motor dysfunction in the open field test. This result confirms the assumption that the antidepressant effect of an Apocynum extract in the FST is specific. Further, it can be speculated that this effect might be related to hyperoside and isoquercitrin which are major flavonoids in the extract.

Flavonoids from Hypericum perforatum show antidepressant activity in the forced swimming test.

It has been shown recently that a flavonoid fraction (fraction II) obtained from a crude extract of Hypericum perforatum (St. John's Wort) was remarkably active in the forced swimming test (FST). Fraction II was further separated using MLCCC to give fractions IIa and IIb. Both fractions proved to be active in the FST at different dosages. Further separation of fraction IIa by preparative HPLC yielded fraction IIa1 which mainly was composed of hyperoside, isoquercitrin, miquelianin and quercitrin, and fraction IIa2 which contained small amounts of hyperoside and astilbin, while most compounds were not known. Both fractions were active after acute treatment in the FST. Isolates obtained from these fractions including hyperoside, isoquercitrin, quercitrin, miquelianin, the aglycone quercetin and astilbin, were tested for activity in the FST. Except for quercetin, quercitrin and astilbin all compounds were active. To exclude false positive results in the FST the validity was checked in open field experiments and in the FST after 12 days of daily treatment.

Solubilized hypericin and pseudohypericin from Hypericum perforatum exert antidepressant activity in the forced swimming test.

It has been shown recently that the fraction IIIc of a crude extract of Hypericum perforatum, (St. John's wort) that contained both hypericin (1) and pseudohypericin (2), was remarkably active in the rats forced swimming test (FST) after Porsolt. However, neither of the naphthodianthrones isolated from this fraction were sufficiently effective when administered suspended in water. The solubility of 1 and 2 is remarkably increased in the presence of a fraction containing procyanidins, especially procyanidin B2, which is present also in the active Hypericum fraction IIIc. The cooperative effect of procyanidins significantly increased the in vivo effects of 1 and 2, which exhibited inverted U-shaped dose response curves, in the FST. The anti-immobility effect of solubilized 1 and 2 was antagonized by the dopamine antagonist sulpiride. These data indicate that naphthodianthrones are antidepressant constituents of H. perforatum and suggest that the dopaminergic system is involved in their action.

Effects of the total extract and fractions of Hypericum perforatum in animal assays for antidepressant activity.

A commercially available extract of the aerial parts of Hypericum perforatum, LI 160, showed pronounced activity in selected animal bioassays. These include the forced swimming test (FST) and the tail suspension test, used to determine antidepressant activity, and tests indicating activity on the central nervous system, such as body temperature and ketamine induced sleeping time. The counteracting effects of drugs known to interfere with the central dopaminergic system strongly suggested that dopamine mediated activity is important for the activity of the extract. Dose-response experiments of the total extract and of fractions rich in flavonoids and napthodianthrones produced inverted U-shaped dose response curves.

Biologically active and other chemical constituents of the herb of Hypericum perforatum L.

Phenylpropanes, flavonol derivatives, biflavones, proanthocyanidins, xanthones, phloroglucinols, some amino acids, naphthodianthrones and essential oil constituents are the natural plant products known from the crude drug of Hypericum perforatum, Hyperici herba. These compounds are discussed with respect to structural features, their concentration, biological activities and their possible contribution to the clinically demonstrated antidepressant efficacy of extracts obtained from Hyperici herba.