St. John's wort extract with a high hyperforin content does not induce P-glycoprotein activity at the human blood-brain barrier.

St. John's wort (SJW) extract, a herbal medicine with antidepressant effects, is a potent inducer of intestinal and/or hepatic cytochrome P450 (CYP) enzymes and P-glycoprotein (P-gp), which can cause clinically relevant drug interactions. It is currently not known whether SJW can also induce P-gp activity at the human blood-brain barrier (BBB), which may potentially lead to decreased brain exposure and efficacy of certain central nervous system (CNS)-targeted P-gp substrate drugs. In this study, we used a combination of positron emission tomography (PET) imaging and cocktail phenotyping to gain a comprehensive picture on the effect of SJW on central and peripheral P-gp and CYP activities. Before and after treatment of healthy volunteers (n = 10) with SJW extract with a high hyperforin content (3-6%) for 12-19 days (1800 mg/day), the activity of P-gp at the BBB was assessed by means of PET imaging with the P-gp substrate [11C]metoclopramide and the activity of peripheral P-gp and CYPs was assessed by administering a low-dose phenotyping cocktail (caffeine, omeprazole, dextromethorphan, and midazolam or fexofenadine). SJW significantly increased peripheral P-gp, CYP3A, and CYP2C19 activity. Conversely, no significant changes in the peripheral metabolism, brain distribution, and P-gp-mediated efflux of [11C]metoclopramide across the BBB were observed following the treatment with SJW extract. Our data suggest that SJW does not lead to significant P-gp induction at the human BBB despite its ability to induce peripheral P-gp and CYPs. Simultaneous intake of SJW with CNS-targeted P-gp substrate drugs is not expected to lead to P-gp-mediated drug interactions at the BBB.

Characterization of application scenario-dependent pharmacokinetics and pharmacodynamic properties of permethrin and hyperforin in a dynamic skin and liver multi-organ-chip model.

Microphysiological systems (MPS) aim to mimic the dynamic microenvironment and the interaction between tissues. While MPS exist for investigating pharmaceuticals, the applicability of MPS for cosmetics ingredients is yet to be evaluated. The HUMIMIC Chip2 ("Chip2″), is the first multi-organ chip technology to incorporate skin models, allowing for the topical route to be tested. Therefore, we have used this model to analyze the impact of different exposure scenarios on the pharmacokinetics and pharmacodynamics of two topically exposed chemicals, hyperforin and permethrin. The Chip2 incorporated reconstructed human epidermis models (EpiDerm™) and HepaRG-stellate spheroids. Initial experiments using static incubations of single organoids helped determine the optimal dose. In the Chip2 studies, parent and metabolites were analyzed in the circuit over 5 days after application of single and repeated topical or systemic doses. The gene expression of relevant xenobiotic metabolizing enzymes in liver spheroids was measured to reflect toxicodynamics effects of the compounds in liver. The results show that 1) metabolic capacities of EpiDerm™ and liver spheroids were maintained over five days; 2) EpiDerm™ model barrier function remained intact; 3) repeated application of compounds resulted in higher concentrations of parent chemicals and most metabolites compared to single application; 4) compound-specific gene induction e.g. induction of CYP3A4 by hyperforin depended on the application route and frequency; 5) different routes of application influenced the systemic concentrations of both parents and metabolites in the chip over the course of the experiment; 6) there was excellent intra- and inter-lab reproducibility. For permethrin, a process similar to the excretion in a human in vivo study could be simulated which was remarkably comparable to the in vivo situation. These results support the use of the Chip2 model to provide information on parent and metabolite disposition that may be relevant to risk assessment of topically applied cosmetics ingredients.

Pharmacokinetics and Metabolism of Liposome-Encapsulated 2,4,6-Trihydroxygeranylacetophenone in Rats Using High-Resolution Orbitrap Liquid Chromatography Mass Spectrometry.

2,4,6-trihydroxy-3-geranylacetophenone (tHGA) is a bioactive compound that shows excellent anti-inflammatory properties. However, its pharmacokinetics and metabolism have yet to be evaluated. In this study, a sensitive LC-HRMS method was developed and validated to quantify tHGA in rat plasma. The method showed good linearity (0.5-80 ng/mL). The accuracy and precision were within 10%. Pharmacokinetic investigations were performed on three groups of six rats. The first two groups were given oral administrations of unformulated and liposome-encapsulated tHGA, respectively, while the third group received intraperitoneal administration of liposome-encapsulated tHGA. The maximum concentration (Cmax), the time required to reach Cmax (tmax), elimination half-life (t1/2) and area under curve (AUC0-24) values for intraperitoneal administration were 54.6 ng/mL, 1.5 h, 6.7 h, and 193.9 ng/mL·h, respectively. For the oral administration of unformulated and formulated tHGA, Cmax values were 5.4 and 14.5 ng/mL, tmax values were 0.25 h for both, t1/2 values were 6.9 and 6.6 h, and AUC0-24 values were 17.6 and 40.7 ng/mL·h, respectively. The liposomal formulation improved the relative oral bioavailability of tHGA from 9.1% to 21.0% which was a 2.3-fold increment. Further, a total of 12 metabolites were detected and structurally characterized. The metabolites were mainly products of oxidation and glucuronide conjugation.

Pharmacokinetics and tissue distribution of Ebracteolatain A, a potential anti-cancer compound, as determined by an optimized ultra-performance liquid chromatography tandem mass spectrometry method.

Ebracteolatain A is a phloroglucinol derivative from the root of Euphorbia ebracteolata Hayata, a Traditional Chinese Medicine also known as Langdu. It has been shown to have good inhibitory effects in breast cancer cells. In this study, a simple, rapid, sensitive, and specific ultra-performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS) method was developed and validated to study the pharmacokinetics (PKs) and tissue distribution of Ebracteolatain A in rats. Ebracteolatain A and Magnolol (internal standard) were extracted by the simple protein precipitation extraction technique using methanol as the precipitating solvent. Chromatographic separation was performed using the Agilent Poroshell 120 EC-C18 column with a mobile phase of acetonitrile:0.1% formic acid (70:30, v/v). The protonated analyte was quantitated in negative ionization by MS/MS via multiple reaction monitoring mode. The assay exhibited a linear dynamic range of 2-2000 ng/mL for Ebracteolatain A in biological samples. The lower limit of quantitation was 2 ng/mL. Non-compartmental PK parameters indicated that Ebracteolatain A was well absorbed into the systemic circulation. The absolute bioavailability of Ebracteolatain A was greater when administered by intraperitoneal administration than by oral administration. The tissue distribution study showed that Ebracteolatain A was distributed in the heart, liver, spleen, lung, kidney, brain, stomach, intestine, uterus, ovary, and breast after intravenous injection. The results of this study further our understanding of the in vivo anti-cancer activity of Ebracteolatain A, and shed light on pharmacological strategies that may be useful for the development of novel breast cancer therapeutics.

No Clinically Relevant Interactions of St. John's Wort Extract Ze 117 Low in Hyperforin With Cytochrome P450 Enzymes and P-glycoprotein.

Hypericum perforatum L. (St. John's wort) is used to treat mild-to-moderate depression. Its potential safety risks are pharmacokinetic drug interactions via cytochrome P450 (CYP) enzymes and P-glycoprotein, presumably caused by hyperforin. In a phase I, open-label, nonrandomized, single-sequence study, the low-hyperforin Hypericum extract Ze 117 was investigated using a drug cocktail in 20 healthy volunteers. No pharmacokinetic interactions of Ze 117 were observed for CYP1A2, CYP2B6, CYP2C9, CYP2C19, CYP3A4, and P-glycoprotein. Area under the curve (AUC) and peak plasma concentration (Cmax ) of the used probe drugs showed 90% confidence intervals (CIs) of the geometric mean ratios of the drugs taken together with Ze 117 vs. probe drug alone, well within the predefined bioequivalence range of 80-125%. Though Ze 117 did not induce dextromethorphan metabolism by CYP2D6, it weakly increased dextromethorphan AUC ratio (mean 147.99, 95% CI 126.32-173.39) but not the corresponding metabolic ratio. Ze 117 does not show clinically relevant pharmacokinetic interactions with important CYPs and P-glycoprotein.

Physiologically Based Pharmacokinetic Modelling of Hyperforin to Predict Drug Interactions with St John's Wort.

BACKGROUND AND OBJECTIVES: Herb-drug interactions with St John's wort (SJW) have been widely studied in numerous clinical studies. The objective of this study was to develop and evaluate a physiologically based pharmacokinetic (PBPK) model for hyperforin (the constituent of SJW responsible for interactions), which has the potential to provide unique insights into SJW interactions and allow prediction of the likely extent of interactions with SJW compared to published interaction reports. METHODS: A PBPK model of hyperforin accounting for the induction of cytochrome P450 (CYP) 3A, CYP2C9 and CYP2C19 was developed in the Simcyp® Simulator (version 17) and verified using published, clinically observed pharmacokinetic data. The predictive performance of this model based on the prediction fold-difference (expressed as the ratio of predicted and clinically observed change in systemic exposure of drug) was evaluated across a range of CYP substrates. RESULTS: The verified PBPK model predicted the change in victim drug exposure due to the induction by SJW (expressed as area under the plasma concentration-time curve (AUC) ratio) within 1.25-fold (0.80-1.25) of that reported in clinical studies. The PBPK simulation indicated that the unbound concentration of hyperforin in the liver was far lower than in the gut (enterocytes). Simulations revealed that induction of intestinal CYP enzymes by hyperforin was found to be more pronounced than the corresponding increase in liver CYP activity (15.5- vs. 1.1-fold, respectively, at a hyperforin dose of 45 mg/day). CONCLUSION: In the current study, a PBPK model for hyperforin was successfully developed, with a predictive capability for the interactions of SJW with different CYP3A, CYP2C9 and CYP2C19 substrates. This PBPK model is valuable to predict the extent of herb-drug interactions with SJW and help design the clinical interaction studies, particularly for new drugs and previously unstudied clinical scenarios.

Determination of phloroglucinol by HPLC-MS/MS and its application to a bioequivalence study in healthy volunteers.

OBJECTIVE: The aim of this study was to compare the pharmacokinetic characteristics of phloroglucinol between an orally disintegrating tablet and an orally lyophilized tablet of phloroglucinol in healthy volunteers under fasting condition. PATIENTS AND METHODS: A rapid and simple method based on high-performance liquid chromatography-tandem mass spectrometry (HPLC-MS/MS) method has been developed and validated for the determination of phloroglucinol in human plasma. The plasma sample was prepared by liquid-liquid extraction, and paracetamol was chosen as the internal standard. Phloroglucinol and IS were separated on a C18 column with a mobile phase consisted of methanol/water (80:20 v/v) with 0.02% formic acid. HPLC-MS/MS analyses were performed on a triple- quadruple tandem mass spectrometer by monitoring protonated parent→daughter ion pairs at m/z 125.0→56.9 for phloroglucinol, and m/z 150.2→107.0 for paracetamol (IS). The method was the high sensitivity with a lower limit of quantification (LLOQ) of 1.976 ng/mL. RESULTS: Drug and IS were detected by HPLC/MS/MS with negative electrospray ionization (ESI). Accuracy and precision for the assay were determined by calculating the intra- and inter-batch variation of quality control (QC) samples at three concentration levels. The relative standard deviation (RSD) was less than 15.0%. The detection and quantitation of drug and IS within 4.5 min make this method suitable for high-throughput analyses. In this study, the Cmax of phloroglucinol were calculated to 515.6 ± 134.4 ng/mL and 536.0 ± 144.8 ng/mL for the test drug and the reference drug, respectively. The AUC0-t values were 459.5 ± 81.03 ng·mL-1·h and 491.8 ± 95.17 ng·mL-1·h for the test drug and the reference drug; 24 subjects completed the study, respectively. The geometric mean ratio (GMR) and the 90% confidence intervals (CIs) of Cmax and AUC0-t of phloroglucinol were 97.1 (90.2-103.9) and 93.8 (88.7-99.2), respectively. CONCLUSIONS: The method was employed for the first time during pharmacokinetic studies of phloroglucinol in human plasma following a single dose of phloroglucinol 160 mg tablets. There was no significant difference in pharmacokinetic profiles between the two treatments.

Gastrointestinal modifications and bioavailability of brown seaweed phlorotannins and effects on inflammatory markers.

Brown seaweeds such as Ascophyllum nodosum are a rich source of phlorotannins (oligomers and polymers of phloroglucinol units), a class of polyphenols that are unique to Phaeophyceae. At present, there is no information on the bioavailability of seaweed polyphenols and limited evidence on their bioactivity in vivo. Consequently, we investigated the gastrointestinal modifications in vitro of seaweed phlorotannins from A. nodosum and their bioavailability and effect on inflammatory markers in healthy participants. In vitro, some phlorotannin oligomers were identified after digestion and colonic fermentation. In addition, seven metabolites corresponding to in vitro-absorbed metabolites were identified. Urine and plasma samples contained a variety of metabolites attributed to both unconjugated and conjugated metabolites (glucuronides and/or sulphates). In both urine and plasma, the majority of the metabolites were found in samples collected at late time points (6-24 h), suggesting colonic metabolism of high-molecular-weight phlorotannins, with three phlorotannin oligomers (hydroxytrifuhalol A, 7-hydroxyeckol, C-O-C dimer of phloroglucinol) identified in urine samples. A significant increase of the cytokine IL-8 was also observed. Our study shows for the first time that seaweed phlorotannins are metabolised and absorbed, predominantly in the large intestine, and there is a large inter-individual variation in their metabolic profile. Three phlorotannin oligomers present in the capsule are excreted in urine. Our study is the first investigation of the metabolism and bioavailability of seaweed phlorotannins and the role of colonic biotransformation. In addition, IL-8 is a possible target for phlorotannin bioactivity.

Brain Uptake of Tetrahydrohyperforin and Potential Metabolites after Repeated Dosing in Mice.

Tetrahydrohyperforin (IDN-5706) is a semisynthetic derivative of hyperforin, one of the main active components of Hypericum perforatum extracts. It showed remarkable positive effects on memory and cognitive performances in wild-type mice and in a transgenic mouse model of Alzheimer's disease, but little was known about the concentrations it can reach in the brain. The investigations reported herein show that repeated treatment of mice with tetrahydrohyperforin (20 mg/kg intraperitoneally, twice daily for 4 days and once on the fifth day) results in measurable concentrations in the brain, up to 367 ng/g brain (∼700 nM) 6 h after the last dose; these concentrations have significant effects on synaptic function in hippocampal slices. The other main finding was the identification and semiquantitative analysis of tetrahydrohyperforin metabolites. In plasma, three hydroxylated/dehydrogenated metabolites were the largest (M1-3) and were also formed in vitro on incubation of tetrahydrohyperforin with mouse liver microsomes; the fourth metabolite in abundance was a hydroxylated/deisopropylated derivative (M13), which was not predicted in vitro. These metabolites were all detected in the brain, with peak areas from 10% (M1) to ∼1.5% (M2, M3, and M13) of the parent compound. In summary, repeated treatment of mice with tetrahydrohyperforin gave brain concentrations that might well underlie its central pharmacological effects. We also provide the first metabolic profile of this compound.

Hypericum perforatum: pharmacokinetic, mechanism of action, tolerability, and clinical drug-drug interactions.

Hypericum perforatum (HP) belongs to the Hypericaceae family and is one of the oldest used and most extensively investigated medicinal herbs. The medicinal form comprises the leaves and flowering tops of which the primary ingredients of interest are naphthodianthrones, xanthones, flavonoids, phloroglucinols (e.g. hyperforin), and hypericin. Although several constituents elicit pharmacological effects that are consistent with HP's antidepressant activity, no single mechanism of action underlying these effects has thus far been found. Various clinical trials have shown that HP has a comparable antidepressant efficacy as some currently used antidepressant drugs in the treatment of mild/moderate depression. Interestingly, low-hyperforin-content preparations are effective in the treatment of depression. Moreover, HP is also used to treat certain forms of anxiety. However, HP can induce various cytochrome P450s isozymes and/or P-glycoprotein, of which many drugs are substrates and which are the main origin of HP-drug interactions. Here, we analyse the existing evidence describing the clinical consequence of HP-drug interactions. Although some of the reported interactions are based on findings from in vitro studies, the clinical importance of which remain to be demonstrated, others are based on case reports where causality can, in some cases, be determined to reveal clinically significant interactions that suggest caution, consideration, and disclosure of potential interactions prior to informed use of HP.

Changes in GABAergic inputs in the paraventricular nucleus maintain sympathetic vasomotor tone in chronic heart failure.

The paraventricular nucleus (PVN) of the hypothalamus is an important region of the brain involved in the regulation of sympathetic vasomotor tone. Accumulating evidence supports the idea that a change in hypothalamic γ-aminobutyric acid (GABA)-ergic inhibitory and glutamatergic excitatory inputs contribute to the exacerbated sympathetic drive in chronic heart failure (HF). The purpose of this study was to determine whether a possible imbalance between glutamatergic and GABAergic inputs to the PVN contributes to increased sympathetic outflow in HF in two different sympathetic territories. Renal (RSNA) and splanchnic sympathetic nerve activity (SSNA), mean arterial blood pressure (MAP) and heart rate were recorded from urethane-anesthetized HF or sham rats. The NMDA-glutamate and GABA-A receptor densities within the PVN were quantified in HF and sham rats by autoradiography. Bilateral microinjection of kynurenic acid (4nmol) into the PVN decreased MAP and RSNA and SSNA in HF but not in sham rats. Furthermore, in response to GABA-A blockade in the PVN by bicuculline (400 pmol), hypertension and SSNA were reduced in HF compared to sham. The quantification of ionotropic NMDA receptors and GABA-A receptors in the PVN showed a significant reduction of GABA-A in HF rats; however, the NMDA density in the PVN did not differ between groups. Thus, this study provides evidence that the sympathoexcitation is maintained by an imbalance between GABAergic and glutamatergic inputs in the PVN in HF. The reduced GABAergic input results in relatively augmented glutamatergic actions in the PVN of HF rats.

Myrtucommulone from Myrtus communis: metabolism, permeability, and systemic exposure in rats.

Nonsteroidal anti-inflammatory drug intake is associated with a high prevalence of gastrointestinal side effects, and severe cardiovascular adverse reactions challenged the initial enthusiasm in cyclooxygenase-2 inhibitors. Recently, it was shown that myrtucommulone, the active ingredient of the Mediterranean shrub Myrtus communis, dually and potently inhibits microsomal prostaglandin E2 synthase-1 and 5-lipoxygenase, suggesting a substantial anti-inflammatory potential. However, one of the most important prerequisites for the anti-inflammatory effects in vivo is sufficient bioavailability of myrtucommulone. Therefore, the present study was aimed to determine the permeability and metabolic stability in vitro as well as the systemic exposure of myrtucommulone in rats. Permeation studies in the Caco-2 model revealed apparent permeability coefficient values of 35.9 ·â€Š10⁻6 cm/s at 37 °C in the apical to basolateral direction, indicating a high absorption of myrtucommulone. In a pilot rat study, average plasma levels of 258.67 ng/mL were reached 1 h after oral administration of 4 mg/kg myrtucommulone. We found that myrtucommulone undergoes extensive phase I metabolism in human and rat liver microsomes, yielding hydroxylated and bihydroxylated as well as demethylated metabolites. Physiologically-based pharmacokinetic modeling of myrtucommulone in the rat revealed rapid and extensive distribution of myrtucommulone in target tissues including plasma, skin, muscle, and brain. As the development of selective microsomal prostaglandin E2 synthase-1 inhibitors represents an interesting alternative strategy to traditional nonsteroidal anti-inflammatory drugs and cyclooxygenase-2 inhibitors for the treatment of chronic inflammation, the present study encourages further detailed pharmacokinetic investigations on myrtucommulone.

Protective role of arzanol against lipid peroxidation in biological systems.

This study examines the protective effect of arzanol, a pyrone-phloroglucinol etherodimer from Helichrysum italicum subsp. microphyllum, against the oxidative modification of lipid components induced by Cu(2+) ions in human low density lipoprotein (LDL) and by tert-butyl hydroperoxide (TBH) in cell membranes. LDL pre-treatment with arzanol significantly preserved lipoproteins from oxidative damage at 2h of oxidation, and showed a remarkable protective effect on the reduction of polyunsaturated fatty acids and cholesterol levels, inhibiting the increase of oxidative products (conjugated dienes fatty acids hydroperoxides, 7ß-hydroxycholesterol, and 7-ketocholesterol). Arzanol, at non-cytotoxic concentrations, exerted a noteworthy protection on TBH-induced oxidative damage in a line of fibroblasts derived from monkey kidney (Vero cells) and in human intestinal epithelial cells (Caco-2), decreasing, in both cell lines, the formation of oxidative products (hydroperoxides and 7-ketocholesterol) from the degradation of unsaturated fatty acids and cholesterol. The cellular uptake and transepithelial transport of the compound were also investigated in Caco-2 cell monolayers. Arzanol appeared to accumulate in Caco-2 epithelial cells. This phenol was able to pass through the intestinal Caco-2 monolayers, the apparent permeability coefficients (P(app)) in the apical-to-basolateral and basolateral-to-apical direction at 2h were 1.93±0.36×10(-5) and 2.20±0.004×10(-5)cm/s, respectively, suggesting a passive diffusion pathway. The results of the work qualify arzanol as a potent natural antioxidant with a protective effect against lipid oxidation in biological systems.

Metabolism of hyperforin, the active constituent of St. John's wort, in human liver microsomes.

The metabolism of hyperforin, one of the pharmacologically most active components of St. John's wort (Hypericum perforatum), was characterized in vitro using human liver microsomes and recombinant heterologously expressed P450 enzymes. A total of 57 hyperforin metabolites were detected. Of those, six were identified as monohydroxylations (M1-M6), while the others were formed via two or more hydroxylation reactions, via dehydrogenation, or by combinations of these reactions. A combined approach of cDNA-expressed recombinant CYPs, CYP-selective chemical inhibitors and correlation with CYP-specific marker activities indicated a central role of the CYP2C and CYP3A families in the metabolism of hyperforin. In addition, hyperforin was found to inhibit CYP2D6 and CYP3A4 model activities quite potently.

Evaluation of cynomolgus monkey pregnane X receptor, primary hepatocyte, and in vivo pharmacokinetic changes in predicting human CYP3A4 induction.

Monkeys have been proposed as an animal model to predict the magnitude of human clinical drug-drug interactions caused by CYP3A4 enzyme induction. To evaluate whether the cynomolgus monkey can be an effective in vivo model, human CYP3A4 inducers were evaluated both in vitro and in vivo. First, a full-length pregnane X receptor (PXR) was cloned from the cynomolgus monkey, and the sequence was compared with those of rhesus monkey and human PXR. Cynomolgus and rhesus monkey PXR differed by only one amino acid (A68V), and both were highly homologous to human PXR (approximately 96%). When the transactivation profiles of 30 compounds, including known inducers of CYP3A4, were compared between cynomolgus and human PXR, a high degree of correlation with EC(50) values was observed. These results suggest that cynomolgus and human PXR respond in a similar fashion to these ligands. Second, two known human CYP3A4 inducers, rifampicin and hyperforin, were tested in monkey and human primary hepatocytes for induction of CYP3A enzymes. Both monkey and human hepatocytes responded similarly to the inducers and resulted in increased RNA and enzyme activity changes of CYP3A8 and CYP3A4, respectively. Lastly, in vivo induction of CYP3A8 by rifampicin and hyperforin was shown by significant reductions of midazolam exposure that were comparable with those in humans. These results show that the cynomolgus monkey can be a predictive in vivo animal model of PXR-mediated induction of human CYP3A4 and can provide a useful assessment of the resulting pharmacokinetic changes of affected drugs.

St. John's wort components and the brain: uptake, concentrations reached and the mechanisms underlying pharmacological effects.

Hypericum perforatum L. (St. John's wort) extracts have gained popularity as an alternative to conventional antidepressant drugs for mild to moderate forms of depressive disorders. New potential psychiatric uses for extracts in obsessive-compulsive disorder, generalised anxiety disorder and alcohol dependence have also been suggested on the basis of animal studies. The neurochemical mechanisms of these central actions are still debated but several components have antidepressant-like and anxiolytic-like effects in animals, or interact with neurotransmitter systems believed to be causally involved in depression, anxiety and in psychiatric illness generally. However, these data should interpreted taking account of the pharmacokinetic data on the main components, particularly those of their brain distribution and concentrations and the relationships with blood concentrations; the (scant) data so far suggest that the acylphloroglucinol hyperforin, the flavonol quercetin and its glycosylated forms and their metabolites, the biflavones amentoflavone and its I3,II8-analog biapigenin and the naphthodianthrones hypericin and pseudohypericin pass the blood-brain barrier poorly in animals. The brain concentrations of all these high-molecular weight, poorly water-soluble compounds after pharmacologically effective doses of the extracts are therefore far below those effective on neurotransmitter receptors and the mechanisms which are obviously important in the central effects of conventional, pharmacologically related drugs. Additional pharmacokinetic data on the brain concentrations of these and other constituents and their metabolites are therefore required for a more meaningful interpretation of the central effects of St. John's Wort extracts.

Intestinal permeability of antivirus constituents from the fruits of Eucalyptus globulus Labill. in Caco-2 Cell Model.

The uptake and transepithelial transport of the three main constituents macrocarpal A (M-A), macrocarpal B (M-B), and cypellocarpa C (Cy-C) from the fruits of Eucalyptus globulus Labill. were investigated. Monolayers of the human intestinal epithelial cancer cell line Caco-2 were incubated with M-A, M-B, and Cy-C to model its intestinal absorption and transport, respectively. The determination of compounds was performed by HPLC. The apparent permeability coefficients (P(app)) for M-A, M-B, and Cy-C in the apical-to-basolateral direction of a Caco-2 monolayer were (1.70+/-0.06)x10(-6), (1.99+/-0.10)x10(-6), and (6.08+/-0.41)x10(-6)cm/s, respectively. In the presence of iodoacetamide, the P(app) of Cy-C were both reducted in apical-to-basolateral and basolateral-to-apical directions. M-A and M-B appear to accumulate in the epithelial cells. The intestinal absorption of M-A, M-B, and Cy-C was passive diffusion as the dominating process and Cy-C was partly ATP-dependent.

Hypericum perforatum: a 'modern' herbal antidepressant: pharmacokinetics of active ingredients.

Hypericum perforatum (St John's Wort [SJW]) counts among the most favourite herbal drugs, and is the only herbal alternative to classic synthetic antidepressants in the therapy of mild to moderate depression. Several clinical studies have been conducted to verify the effectiveness of ethanolic or methanolic extracts of SJW. Alcoholic SJW extracts are a mixture of substances with widely varying physical and chemical properties and activities. Hyperforin, a phloroglucinol derivative, is the main source of pharmacological effects caused by the consumption of alcoholic extracts of SJW in the therapy of depression. However, several studies indicate that flavone derivatives, e.g. rutin, and also the naphthodianthrones hypericin and pseudohypericin, take part in the antidepressant efficacy. In contrast to the amount of documentation concerning clinical efficacy, oral bioavailability and pharmacokinetic data about the active components are rather scarce. The hyperforin plasma concentration in humans was investigated in a small number of studies. The results of these studies indicate a relevant plasma concentration, comparable with that used in in vitro tests. Furthermore, hyperforin is the only ingredient of H. perforatum that could be determined in the brain of rodents after oral administration of alcoholic extracts. The plasma concentrations of the hypericins were, compared with hyperforin, only one-tenth and, until now, the hypericins could not be found in the brain after oral administration of alcoholic H. perforatum extracts or pure hypericin. Until now, the pharmacokinetic profile of the flavonoids in humans after oral administration of an alcoholic H. perforatum extract has been investigated in only one study. More data are available for rutin and the aglycone quercetin after administration of pure substances or other flavonoid sources.

St. John's wort (Hypericum perforatum) and breastfeeding: plasma and breast milk concentrations of hyperforin for 5 mothers and 2 infants.

BACKGROUND: Herbal preparations for depression, such as St. John's wort, are often preferred over pharmaceutical preparations by mothers and midwives after childbirth because these preparations are available to patients as over-the-counter "natural" treatments and are popularly assumed to be safe. The only existing report on St. John's wort excretion into human milk showed that only 1 active component (hyperforin) was detectable in breast milk, but was not detectable in the infants' plasma. Another report found more cases of minor problems in infants breast-fed by women taking St. John's wort. However, significance was reached only in comparison with disease-matched women (p<.01), not healthy controls (p=.20). METHOD: Five mothers who were taking 300 mg of St. John's wort 3 times daily (LI 160 [Jarsin], Lichtwer Pharma GmbH; Berlin, Germany) and their breastfed infants were assessed. Thirty-six breast milk samples (foremilk and hindmilk collected during an 18-hour period) and 5 mothers' and 2 infants' plasma samples were analyzed for hyperforin levels by tandem mass spectrometry (LC/MS/MS; limit of quantification=0.1 ng/mL). Data were gathered from January 2001 to February 2002. RESULTS: Hyperforin is excreted into breast milk at low levels. However, the compound was at the limit of quantification in the 2 infants' plasma samples (0.1 ng/mL). Milk/plasma ratios ranged from 0.04 to 0.13. The relative infant doses of 0.9% to 2.5% indicate that infant exposure to hyperforin through milk is comparable to levels reported in most studies assessing anti-depressants or neuroleptics. No side effects were seen in the mothers or infants. CONCLUSION: These results add to the evidence of the relative safety of St. John's wort while breast-feeding found in previous observational studies.

Investigation of pharmacokinetic data of hypericin, pseudohypericin, hyperforin and the flavonoids quercetin and isorhamnetin revealed from single and multiple oral dose studies with a hypericum extract containing tablet in healthy male volunteers.

Hypericins, hyperforin and flavonoids are discussed as the main components contributing to the antidepressant action of St. John's wort (Hypericum perforatum). Therefore, the objective of the two open phase I clinical trials was to obtain pharmacokinetic data of these constituents from a hypericum extract containing tablet: hypericin, pseudohypericin, hyperforin, the flavonoid aglycone quercetin, and its methylated form isorhamnetin. Each trial included 18 healthy male volunteers who received the test preparation, containing 900 mg dry extract of St John's wort (STW 3-VI, Laif 900), either as a single oral dose or as a multiple once daily dose over a period of 14 days. Concentration/time curves were determined for the five constituents, for 48 h after single dosing and for 24 h on day 14 at the end of 2 weeks of continuous daily dosing. After single dose intake, the key pharmacokinetic parameters were determined as follows: Hypericin: Area under the curve (AUC(0-infinity)) = 78.33 h x ng/ml, maximum plasma concentration (Cmax) = 3.8 ng/ml, time to reach Cmax (tmax) = 7.9 h, and elimination half-life (t1/2) = 18.71 h; pseudohypericin: AUC(0-infinity) = 97.28 h x ng/ml, Cmax = 10.2 ng/ml, tmax = 2.7 h, t1/2 = 17.19 h; hyperforin: AUC(0-infinity) = 1550.4 h x ng/ml, Cmax = 122.0 ng/ml, tmax = 4.5 h, t1/2 = 17.47 h. Quercetin and isorhamnetin showed two peaks of maximum plasma concentration separated by about 3-3.5 h. Quercetin: AUC(0-infinity) = 417.38 h x ng/ml, Cmax (1) = 89.5 ng/ml, tmax (1) = 1.0 h, Cma (2) = 79.1 ng/ml, tmax (2) = 4.4 h, t1/2 = 2.6 h; isorhamnetin: AUC(0-infinity) = 155.72 h x ng/ml, Cmax (1) = 12.5 ng/ml, tmax (1) = 1.4 h, Cmax (2) = 14.6 ng/ml, tmax (2) = 4.5 h, t1/2 = 5.61 h. Under steady state conditions reached during multiple dose administration similar results were obtained. Further pharmacokinetic characteristics calculated from the obtained data were the mean residence time (MRT), the lag-time, the peak-trough fluctuation (PTF), the lowest observed plasma concentration (Cmin), and the average plasma concentration (Cav). The data obtained for the five consitituents generally corresponded well with values previously published. The trial preparation was well tolerated.