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

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.

Isolation and characterization of antioxidant phenolic compounds from the aerial parts of Hypericum hyssopifolium L. by activity-guided fractionation

Dried methanol extract of Hypericum hyssopifolium subsp. elongatum var. elongatum was dissolved in distilled water, and then fractioned by re-extracting with petroleum ether, chloroform, and ethyl acetate, subsequently. Antioxidant and 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical-scavenging activities of these fractions were determined, in vitro. The amounts of total phenolic compounds were also determined. None of these fractions showed antioxidant activity, in contrast water and ethyl acetate fractions acted as prooxidant. However, the ethyl acetate fraction exhibited the highest DPPH radical-scavenging activity and the amount of its total phenolic compound was highest, too. Therefore, ethyl acetate fraction was subjected to further separation by chromatographic methods. Thus, five flavonoids (I3,II8-biapigenin, quercetin, quercetin-3-O-alpha-L-arabinofuranoside, quercetin-3-O-beta-D-galactopyranoside, quercetin-3-O-beta-D-galactopyranoside-7-O-beta-D-glucopyranoside) and a napthodianthrone (hypericin) were isolated, and their structures were determined by UV, IR, NMR, and MS spectroscopic methods. All isolated compounds showed antioxidant and DPPH radical-scavenging activities. Although, I3,II8-biapigenin and hypericin were able to show highest antioxidant activity, they had the lowest DPPH radical-scavenging activities. From these results, it can be suggested that these compounds may be used as potential antioxidants. In addition, the petroleum ether fraction was subjected to silica gel column chromatography (CC). Then, n-dotriacontanyl hexadecanoate, bis(2-methylheptyl) phthalate, and beta-sitosterol were isolated from it. It is of interest to present the spectral data of bis(2-methylheptyl) phthalate first time in the present study.

Step by step removal of hyperforin and hypericin: activity profile of different Hypericum preparations in behavioral models

Herbal extracts of Hypericum perforatum L. (St. John's wort, SJW) are now successfully competing for status as a standard antidepressant therapy. Because of this, great effort has been devoted to identifying the antidepressive active compounds. In the present study we used the following strategy to evaluate the relative pharmacological importance of various extract components: 1. preparation of an hydroalcoholic SJW extract containing both hyperforin (3.2%) and hypericin (0.15%) (extract A); 2. step by step removal of hyperforin and hypericin led to the following extracts: Extract B, devoid of hyperforin but still containing hypericin (0.14%) and Extract C, free of hypericin and hyperforin but enriched in flavonoids ( approximately 12%). We characterized the in vivo activity profile of all three preparations using the tail suspension test (TST) in mice and the forced swimming test (FST) in rats as screening models. We further investigated the activity of pure hyperforin. Extract B and C (500 mg/kg each) as well as pure hyperforin (8 mg/kg) significantly shortened immobility time in the TST after acute pre-treatment whereas extract A was inactive. In the FST all three extracts decreased immobility time in a dosage of 500 mg/kg after acute as well as after repeated treatment. The present results clearly show that an SJW extract free of hyperforin and hypericin exerts antidepressant activity in behavioral models, supporting our working hypothesis that flavonoids are part of the constituents responsible for the therapeutic efficacy of SJW extracts. We also could show that hyperforin contributes to the beneficial properties of SJW extract, confirming the hypothesis that the crude SJW extract contains several constituents with antidepressant activity.

Quercetin attenuates oxygen-glucose deprivation- and excitotoxin-induced neurotoxicity in primary cortical cell cultures

The possible role of quercetin, a naturally occurring plant flavonoid, in protecting against oxygen-glucose deprivation (OGD)-, excitotoxins-, and free radical-induced neuronal injury in mouse cortical cell cultures was investigated. Pre- and co-treatment with quercetin (100 microM) inhibited 50 min OGD-, 20 microM N-methyl-D-aspartate (NMDA)-, and 50 microM kainate-induced neurotoxicity by 36, 22, and 61%, respectively. Quercetin significantly ameliorated free radical-induced neuronal injury caused by buthionine sulfoximine, sodium nitroprusside, ZnCl(2), and FeCl(2). These results suggest that quercetin may contribute a neuroprotective action against ischemic neural injury, partially via antioxidant actions.

Pharmacological activity of hyperforin acetate in rats

Hyperforin, the main antidepressant component of Hypericum extract, is not stable with regard to heat and light. Therefore, we investigated a newly synthetized derivative, hyperforin acetate. Herein we demonstrate its efficacy in animal models sensitive to antidepressant and anxiolytic drugs. In the forced swimming test, triple administration of hyperforin (5-20 mg/kg) significantly reduced the immobility time of rats, while in the learned helplessness test a daily treatment of 10 mg/kg for seven consecutive days was necessary to elicit an antidepressant effect. In the elevated plus-maze and in the light-dark test, the acute administration of hyperforin acetate (3-5 mg/kg) exerted an anxiolytic activity, which, however, was smaller than that of diazepam. The effect was inhibited by the pretreatment of rats with metergoline, a serotoninergic antagonist, but not with CGS-8216, a benzodiazepine receptor antagonist. Hyperforin acetate (3-10 mg/kg) was also able to reduce locomotion in rats without eliciting myorelaxant activity. As Hypericum extract was claimed to exert a potential influence on the liver drug metabolizing system, we showed that neither acute nor repeated oral doses of hyperforin acetate altered pentobarbital sleeping time in rats. Taken together, the present results show that hyperforin acetate is a pharmacologically active derivative of hyperforin and may be a starting point from which to develop new compounds for therapeutic purposes.

Biorelevant dissolution testing of St John's wort products

In contrast to chemically defined drugs, most herbal medicinal products (HMPs) are poorly characterized in terms of their pharmaceutical properties. In many cases it is assumed that the plant extract as a whole is the active moiety, since it is often difficult to identify the individual components responsible for the pharmacological activity and even more difficult to assess synergies among the various components. However, where the active components have been identified, it should be possible to compare products with respect not only to content uniformity but also to their biopharmaceutical properties. The aim of this study was to investigate and compare the dissolution characteristics of several St John's wort products under biorelevant conditions. Components of St John's wort known, or suspected, to play a role in its antidepressant activity include phloroglucines, naphthodianthrones and the flavonoids. Since these groups have a broad spectrum of polarity and solubility, dissolution was studied for representative compounds from each group. Although the labelling indicates that several of the products studied should be pharmaceutically equivalent, dissolution under biorelevant conditions revealed that they have quite different release profiles and cannot be considered switchable. It was concluded that biorelevant dissolution testing can be a powerful tool for comparing HMPs as well as synthetically produced drug products.

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.

Antimicrobial studies on three species of Hypericum from the Canary Islands

The antimicrobial activity of several extracts and fractions of the aerial parts of Hypericum canariense, Hypericum glandulosum and Hypericum grandifolium was investigated using the disc diffusion and broth microdilution methods against twelve reference microorganisms (eight bacterial and four fungal strains). The methanol extract and chloroform fraction of H. canariense, as well as the methanol extracts, butanol and chloroform fractions of both H. glandulosum and H. grandifolium exhibited a good antibacterial activity against four Gram-positive bacteria (Bacillus cereus var. mycoides, Micrococcus luteus, Staphylococcus aureus and Staphylococcus epidermidis) and the Gram-negative bacterium Bordetella bronchiseptica with the diameters of growth inhibition area in the range 10-25 mm and MICs values between 0.03 and 0.29 mg/ml. Neither the infusions and aqueous fractions of the species studied nor the butanol fraction of H. canariense showed any antibacterial activity against the tested microorganisms. Amongst the active extracts, the minimum inhibitory concentration (MIC) determination showed that the H. canariense chloroform fraction was the most active against M. luteus, S. aureus and S. epidermidis. No antifungal activity was seen with any of the extracts or fractions tested. The results of this study support the use of these species in Canarian traditional medicine to treat skin infections.

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.

St. John's wort and depression: efficacy, safety and tolerability-an update

St. John's wort (Hypericum perforatum L.) is a medicinal plant traditionally used, both externally and internally, in all Europe for many pathologies. Paracelsus named it "arnica of the nerves" because of its empirical use in nervous diseases. In the last two decades many studies have proved the efficacy of some St. John's wort extracts in mild to moderate depression and it has been successful as an antidepressant both in Europe and the US. Its high efficacy and tolerability is unquestionable and from the clinical studies the activity is comparable to other antidepressants while lacking major side effects, making it a safe antidepressant.However, recently its potential to induce the metabolism of co-administered medications has been reported because it may potentate certain enzymes of the cytochrome P450 enzyme system. This resulted in a lowering of serum concentration of a number of concomitant drugs, including warfarin, digoxin, theophylline, cyclosporin, and indinavir. Many drugs and also several common foods and drinks can influence this enzyme system. So, even if its safety has been well established, physicians should be aware that St. John's wort administration might significantly affect other prescribed medicines.

Quantitative analysis of the active components and the by-products of eight dry extracts of Hypericum perforatum L. (St John's Wort)

The major components of eight different batches of commercially available dry extracts of Hypericum perforatum L. were quantified. Hyperforin (1), hypericin (2) and flavonoids, which are considered to play key roles in the treatment of mild and moderate depressive disorders, were determined by HPLC methods. The contents of 1, 2 and flavonoids were found to be in the range of 1.3-3.9%, 0.19-0.30%, and 4.8-11.4%, respectively. Generally extracts contained, besides the so-called active components, a wide variety of by-products which may act partially as co-effectors and affect the technological properties of the extracts. Water-soluble sugars form one of the main groups of these by-products, and a procedure for the purification and quantification of such sugars in H. perforatum using HPLC with refractive index detection has been established. Native fructose, glucose and sucrose, as well as lactose added during the processing of the extracts, were determined. The total sugar content in the dry herbal extracts varied from 19 to 25% by weight. Further, citric acid (0.9-2.3%) and malic acid (2.3-3.1%) were determined by HPLC, tannins (6.2-9.0%) and total ash (4.9-8.4%) were quantified according to the methods described in the European Pharmacopoeia, and the content of the total protein (3.9-8.3%) was estimated by elemental analysis. Thus, 60-70% of the compounds of the H. perforatum dry extracts have been quantified.

Biological activity of astilbin from Dimorphandra mollis against Anticarsia gemmatalis and Spodoptera frugiperda

Astilbin was isolated in high yield from Dimorphandra mollis, and its insecticidal and growth inhibiting activity by stomach ingestion were evaluated against Anticarsia gemmatalis and Spodoptera frugiperda. The insecticidal activity of astilbin, the weight reduction of the larval phase and the prolongation of the larval and pupal phases were verified for both species. Astilbin was identified on the base of its NMR, MS and physical data.

Excipient compatibility study of Hypericum perforatum extract (St. John's wort) using similarity metrics to track phytochemical profile changes

The formulation of botanical dietary supplements is challenging due to their complex activity-composition relationship, as well as physical and chemical stability issues. As excipient compatibility testing is a major component of sound formulation development, the objectives of this work were: (1) explore excipient compatibility storage paradigms; (2) determine interactions between phytochemicals of interest in Saint John's Wort (SJW) with several excipients; and (3) explore the application of similarity metrics to the data. Modifications to conventional isothermal stress testing paradigms included additional storage conditions of heat and moisture (5, 50 degrees C, 5 and 0% added water), as well as more rigorous controls. Binary blends of SJW and ten commonly used excipients were prepared and neat SJW was used as control. After 3 weeks, the percentage remaining of each phytochemical was determined by HPLC. Several similarity metrics were applied to the data. Common storage paradigms were suitable for excipient compatibility testing when controls of neat material are stored under similar conditions and the percentage of phytochemicals remaining in excipient:SJW blends and neat SJW are compared. Excipient incompatibilities were determined for SJW phytochemicals of interest. Similarity metrics applied to the phytochemical profiles conveniently summarized the data. This work allows logical decisions to be made regarding the formulation of SJW.

Long-term effects of St. John's wort and hypericin on monoamine levels in rat hypothalamus and hippocampus

Hypericum perforatum L. (St. John's wort) is one of the leading psychotherapeutic phytomedicines and, because of this, great effort has been devoted to clarifying its mechanism of action. Chronic effects of St. John's wort and hypericin, one of its major active compounds, on regional brain amine metabolism have not been reported yet. We used a high-performance liquid chromatography system to examine the effects of short-term (2 weeks) and long-term (8 weeks) administration of imipramine, Hypericum extract or hypericin on regional levels of serotonin (5-HT), norepinephrine, dopamine and their metabolites in the rat brain. We focused our interest on the hypothalamus and hippocampus, as these brain regions are thought to be involved in antidepressant drug action. Imipramine (15 mg/kg, p.o.), Hypericum extract (500 mg/kg, p.o.), and hypericin (0.2 mg/kg, p.o.) given daily for 8 weeks significantly increased 5-HT levels in the hypothalamus (P<0.05). The 5-HT turnover was significantly lowered in both brain regions after 8 weeks of daily treatment with the Hypericum extract (both P<0.05). Consistent changes in catecholamine levels were only detected in hypothalamic tissues after long-term treatment. Comparable to imipramine, Hypericum extract as well as hypericin significantly decreased 3,4-dihydroxyphenylacetic acid and homovanillic acid levels in the hypothalamus (P<0.01). Our data clearly show that long-term, but not short-term administration of St. John's wort and its active constituent hypericin modify levels of neurotransmitters in brain regions involved in the pathophysiology of depression.

Hypericum perforatum--chemical profiling and quantitative results of St. John's Wort products by an improved high-performance liquid chromatography method

The analysis of flavonoids, naphthodianthrones, and the phloroglucinol derivative hyperforin in H. perforatum is described in this article. In a 35-min HPLC run nine major compounds could be identified and baseline separated in the methanolic plant extracts. For an optimum separation the mobile phase consisted of 10 mM ammonium acetate buffer (pH 5.0) and an acetonitrile/methanol mixture; a Synergi MAX-RP 80 A column (C-12 material) was used as stationary phase. Detection was performed at 270 nm, and the identity of the compounds was confirmed in an LC-MS experiment. Commercial St. John's Wort products were analyzed and qualitative and quantitative results are discussed.

Antidepressant effects of the methanol extract of several Hypericum species from the Canary Islands

The aim of the present study was to investigate several neuropharmacological effects of the methanol extract of the aerial parts in blossom of Hypericum canariense, H. glandulosum, H. grandifolium and H. reflexum (Hypericaceae). These extracts did not alter significantly the locomotor activity, body temperature or the pentobarbital-induced sleeping time, with the exception of H. reflexum which significantly potentiated pentobarbital-induced sleeping time at both doses assayed (500 and 1000 mg/kg p.o.). Additionally, neither muscle relaxant nor anticholinergic activity was observed. These extracts antagonized the ptosis and/or motor depression induced by tetrabenazine and also shortened the immobility time in the forced swimming test. Moreover, the H. glandulosum and H. grandifolium extracts at 1000 mg/kg p.o. potentiated the head twitches induced by 5-HTP. These observations suggest that the methanol extract of the Hypericum species in doses of 500-1000 mg/kg p.o. possess antidepressant activity in mice, without inducing significant muscle relaxation, anticholinergic and sedative properties.

High performance liquid chromatographic analysis of St. John's wort with photodiode array detection

An RP-HPLC method with photodiode array detection was established for the determination of major constituents (rutin, hyperoside, isoquercitrin, quercitrin, quercetin, pseudohypericin, hyperforin and hypericin) in St. John's Wort dietary supplements. The samples were extracted with methanol by means of sonication in low temperature. The extraction was rapid, with two steps of sonication (30 min each) recovering more than 99% of the major constituents in St. John's Wort samples. The major components were separated by RP-18 chromatography column using a 60-min water-acetonitrile-methanol-trifluoroacetic acid gradient. The quantification was performed by using external standards. Sample preparation and stability of methanolic extract of St. John's Wort were extensively explored. It is worth noting that the major constituents in the methanolic extract of St John's Wort, especially hypericin and pseudohypericin, might be retained by some filter cartridges during the filtration. The current method may serve as a valuable tool for the QA/QC of St. John's Wort dietary supplements.

Attractive and defensive functions of the ultraviolet pigments of a flower (Hypericum calycinum)

The flower of Hypericum calycinum, which appears uniformly yellow to humans, bears a UV pattern, presumably visible to insects. Two categories of pigments, flavonoids and dearomatized isoprenylated phloroglucinols (DIPs), are responsible for the UV demarcations of this flower. Flavonoids had been shown previously to function as floral UV pigments, but DIPs had not been demonstrated to serve in that capacity. We found the DIPs to be present in high concentration in the anthers and ovarian wall of the flower, suggesting that the compounds also serve in defense. Indeed, feeding tests done with one of the DIPs (hypercalin A) showed the compound to be deterrent and toxic to a caterpillar (Utetheisa ornatrix). The possibility that floral UV pigments fulfill both a visual and a defensive function had not previously been contemplated. DIPs may also serve for protection of female reproductive structures in other plants, for example in hops (Humulus lupulus). The DIPs of hops are put to human use as bitter flavoring agents and preservatives in beer.

Selected physical and chemical properties of commercial Hypericum perforatum extracts relevant for formulated product quality and performance

OBJECTIVE

The complex composition-activity relationship of botanicals such as St John's Wort (SJW) presents a major challenge to product development, manufacture, and establishment of appropriate quality and performance standards for the formulated products. As part of a larger study aimed at addressing that challenge, the goals of the present study are to (1) determine and compare the phytochemical profiles of 3 commercial SJW extracts; (2) assess the possible impact of humidity, temperature, and light on their stability; and (3) evaluate several physical properties important to the development of solid dosage forms for these extracts.

METHODS

An adapted analytical method was developed and validated to determine phytochemical profiles and assess their stability. The extract physical properties measured were particle size (Malvern Mastersizer), flow (Carr's compressibility index; minimum orifice diameter), hygroscopicity (method of Callahan et al), and low-pressure compression physics (method of Heda et al).

RESULTS

The phytochemical properties differed greatly among the extracts and were extremely sensitive to changes in storage conditions, with marked instability under conditions of elevated humidity. All extracts exhibited moderate to free-flow properties and were very hygroscopic. Compression properties varied among the extracts and differed from a common use excipient, microcrystalline cellulose.

CONCLUSIONS

Three commercial sources of SJW extracts exhibited different physical and chemical properties. Standardization to 1 or 2 marker compounds does not ensure chemical equivalence nor necessarily equivalent pharmacological activity. Flow and compression properties appear suitable for automatic capsule-filling machines, but hygroscopicity and the moisture sensitivity of the phytochemical profile are concerns.

St John's wort (Hypericum perforatum L.): a review of its chemistry, pharmacology and clinical properties

The chemical composition of St. John's wort has been well-studied. Documented pharmacological activities, including antidepressant, antiviral, and antibacterial effects, provide supporting evidence for several of the traditional uses stated for St John's wort. Many pharmacological activities appear to be attributable to hypericin and to the flavonoid constituents; hypericin is also reported to be responsible for the photosensitive reactions that have been documented for St. John's wort. With regard to the antidepressant effects of St John's wort, hyperforin, rather than hypericin as originally thought, has emerged as one of the major constituents responsible for antidepressant activity. Further research is required to determine which other constituents contribute to the antidepressant effect. Evidence from randomised controlled trials has confirmed the efficacy of St John's wort extracts over placebo in the treatment of mild-to-moderately severe depression. Other randomised controlled studies have provided some evidence that St John's wort extracts are as effective as some standard antidepressants in mild-to-moderate depression. There is still a need for further trials to assess the efficacy of St John's wort extracts, compared with that of standard antidepressants, particularly newer antidepressant agents, such as the selective serotonin reuptake inhibitors (recent comparative studies with fluoxetine and sertraline have been conducted). Also, there is a need for further studies in well-defined groups of patients, in different types of depression, and conducted over longer periods in order to determine long-term safety. St John's wort does appear to have a more favourable short-term safety profile than do standard antidepressants, a factor that is likely to be important in patients continuing to take medication. Concerns have been raised over interactions between St John's wort and certain prescribed medicines (including warfarin, ciclosporin, theophylline, digoxin, HIV protease inhibitors, anticonvulsants, selective serotonin reuptake inhibitors, triptans, oral contraceptives); advice is that patients taking these medicines should stop taking St John's wort, generally after seeking professional advice as dose adjustment of conventional treatment may be necessary.

Monoamine oxidase inhibitory activity of some Hypericum species native to South Brazil

The total methanol crude extracts and petroleum ether, chloroform, and methanol fractions obtained from Hypericum species, H. caprifoliatum, H. carinatum, H. connatum, H. cordatum, H. myrianthum, H. piriai, H. polyanthemum and H. brasiliense, all native to South Brazil, were assayed for monoamine oxidase A (MAO A) and MAO B inhibitory activity in rat brain mitochondrial preparations at concentrations ranging from 1 to 20microg mL(-1). Three benzopyrans, HP1 (6-isobutyryl-5,7-dimethoxy-2,2-dimethylbenzopyran), HP2 (7-hydroxy-6-isobutyryl-5-methoxy-2,2-dimethylbenzopyran) and HP3 (5-hydroxy-6-isobutyryl-7-methoxy-2,2dimethylbenzopyran) isolated from H. polyanthemum were also tested at maximal concentrations of 150, 150 and 75/microM, respectively. The lipophilic extracts of H. polyanthemum, H. caprifoliatum and H. piriai displayed MAO A inhibitory activity greater than 50%. Among the benzopyrans, only HP3 showed significant activity, with an IC50 value of 22 microM. The total methanol crude extracts of aerial parts from H. carinatum, H. connatum, H. cordatum, H. polyanthemum and H. piriai were evaluated for antidepressant activity in the Porsolt's forced swimming test in Wistar rats (270 mg kg(-1) day(-1); i.p); however, none of them showed activity.

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.

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.

Determination of flavone, flavonol, and flavanone aglycones by negative ion liquid chromatography electrospray ion trap mass spectrometry

Eleven naturally occurring flavonoid aglycones, belonging to the representative flavone, flavonol, and flavanone types were separated by high performance liquid chromatography and analyzed on-line with negative ion electrospray ionization tandem mass spectrometry (ESI-MS/MS). In order to resolve the MS/MS spectra obtained, each compound was reinvestigated by direct loop injections using an ion trap mass spectrometer. The MSn spectra obtained allowed us to propose plausible schemes for their fragmentation supported by the analysis of five complementary synthetic flavonoid aglycones. The negative ion ESI-MS/MS behavior of the different aglycones investigated in this study revealed interesting differences when compared with the previously described patterns obtained using various ionization techniques in positive ion. Thus, concerning the retro Diels-Alder (RDA) fragmentation pathways, several structurally informative anions appeared highly specific of the negative ion mode. In addition, a new lactone-type structure, instead of a ketene, was proposed for a classic RDA diagnostic ion. We also observed unusual CO, CO2, and C3O2 losses which appear to be characteristic of the negative ion mode. All these results and these unusual neutral losses show that the negative ion mode was a powerful complementary tool of the positive ion mode for the structural characterization of flavonoid aglycones by ESI-MS/MS.

St John's wort: Prozac from the plant kingdom

Conventional antidepressants are associated with a range of adverse drug reactions. The herb Hypericum perforatum (St John's wort) might offer another approach to the treatment of depression. Biochemical and animal studies suggest that the phloroglucinol derivative hyperforin is the main active ingredient of St John's wort, and inhibits the synaptosomal uptake of 5-HT, noradrenaline, dopamine, glutamate and GABA. St John's wort has been shown to alleviate symptoms of mild to moderate depression, and seems to offer significant advantages over conventional antidepressants because it is associated with fewer adverse reactions. However, important herb--drug interactions have been described. In view of its efficacy and safety records, St John's wort should be considered for the first-line treatment of mild to moderate depression.

Anti-inflammatory and analgesic activity of Hypericum empetrifolium Willd. (Guttiferae)

A methanolic extract of Hypericum empetrifolium Willd. was evaluated for anti-inflammatory properties in rats (subplantar edema induced by carrageenan) and analgesic effects in mice (hot plate and writhing tests). Our results showed that the methanolic extract exhibits a significant anti-inflammatory activity and analgesic effects only in one of the experimental models (writhing test). Therefore, we may suppose that the methanolic extract of H. empetrifolium is active against inflammatory pain.

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.

Pharmacognosy in the 21st century

The term pharmacognosy as a constituent scientific discipline of pharmacy has been in use for nearly 200 years, and it refers to studies on natural product drugs. During the last half of the 20th century, pharmacognosy evolved from being a descriptive botanical subject to one having a more chemical and biological focus. At the beginning of the 21st century, pharmacognosy teaching in academic pharmacy institutions has been given new relevance, as a result of the explosive growth in the use of herbal remedies (phytomedicines) in modern pharmacy practice, particularly in western Europe and North America. In turn, pharmacognosy research areas are continuing to expand, and now include aspects of cell and molecular biology in relation to natural products, ethnobotany and phytotherapy, in addition to the more traditional analytical method development and phytochemistry. Examples are provided in this review of promising bioactive compounds obtained in two multidisciplinary natural product drug discovery projects, aimed at the elucidation of new plant-derived cancer chemotherapeutic agents and novel cancer chemopreventives, respectively. The systematic study of herbal remedies offers pharmacognosy groups an attractive new area of research, ranging from investigating the biologically active principles of phytomedicines and their mode of action and potential drug interactions, to quality control, and involvement in clinical trials.