Activation of CREB by St. John’s wort may diminish deletorious effects of aging on spatial memory

St. John’s wort (Hypericum perforatum) is one of the leading psychotherapeutic phytomedicines. Beneficial effects of this herb in the treatment of mild to moderate depression are well known. In this study we tested a hypothesis that St. John’s wort alleviates age-related memory impairments by increasing the levels of cyclic adenosine 3′, 5′-monophosphate response element binding protein (CREB) and phosphorylated CREB (pCREB) in hippocampus. Middleaged rats (18 month-old) displayed a decline in the acquisition of spatial working memory (p < 0.001) in the Morris water maze (MWM). Chronic administration of Hypericum perforatum (HP) (350 mg/kg for 21 days), potently and significantly improved the processing of spatial information in the aged rats (p < 0.001). Also the herb increased the levels of pCREB in the aged rat’s hippocampus (p < 0.01) as measured by western immunoblotting. Aging caused significant locomotor impairments as tested in the open field (p < 0.001) but not in the MWM test. However, these were unaffected by treatment with HP. Thus, this study indicates that St. John’s wort effectively prevents aging-induced deterioration of spatial memory in 18 month-old rats, possibly by the activation of CREB regulated genes associated with memory formation. It appears that mechanism is probably inactive in young rats.     

Effect of St. John’s wort supplementation on the pharmacokinetics of bupropion in healthy male Chinese volunteers

1. The objective of this study was to investigate the effects of continuous St. John’s wort administration on single-dose pharmacokinetics of bupropion, a substrate of cytochrome P450 (CYP) 2B6, in healthy Chinese volunteers.

2. Eighteen unrelated healthy male subjects participated in this study. The single-dose pharmacokinetics of bupropion and hydroxybupropion were determined before (control) and after a long-term period of St. John’s wort intake (325?mg, three times a day for 14 days). Plasma concentrations of bupropion and hydroxybupropion were determined before and at 0.5, 1, 2, 3, 4, 5, 6, 8, 10, 12, 24, 36, 48, 60 and 72?h after dosing.

3. St. John’s wort treatment decreased the area under the concentration versus time curve extrapolated to infinity of bupropion in healthy volunteers from 1.4 μg·h ml^?1 (95% confidence interval [CI]?=?1.2–1.6 μg·h ml^?1) after bupropion alone to 1.2 μg·h ml^?1 (95% CI?=?1.1–1.3 μg·h ml^?1) during St. John’s wort treatment. St. John’s wort treatment increased the oral clearance of bupropion from 108.3 l h^?1 (95% CI?=?95.4–123.0 l h^?1) to 130.0 l h^?1 (95% CI?=?118.4–142.7 l h^?1). No change in the time to peak concentration (t_max) and the blood elimination half-life (t_1/2) of bupropion was observed between the control and St. John’s wort-treated phases. However, the half-life of hydroxybupropion between two phases had a significant difference by a Student’s t test after logarithmic transformation. St. John’s wort treatment decreased the half-life of hydroxybupropion from 26.7?h (95% CI?=?23.8–29.9?h) to 24.4?h (95% CI?=?21.9–27.3?h).

4. St. John’s wort decreased, to a statistically significant extent, the plasma concentrations of bupropion, probably mainly by increasing the clearance of bupropion.

     

Inhibitory effect of the herbal antidepressant St. John’s wort (Hypericum perforatum) on rat gastric motility

St. John’s wort (Hypericum perforatum) is a highly popular and effective herbal antidepressant that clinically interacts with a number of conventional drugs. Because alterations in gastric emptying can cause pharmacokinetic interactions, in the present study we evaluated the effect of a standardized extract prepared from the flowering tops of Hypericum perforatum (SJW extract) on rat gastric motility. Orally administered SJW extract delayed gastric emptying in vivo. In vitro studies showed that SJW extract was significantly more active in inhibiting acetylcholine (or prostaglandin E₂)-induced contractions than electrical field stimulation (EFS)-induced contractions. The effect of SJW extract on EFS-induced contractions was unaffected by drugs that inhibit intrinsic inhibitory nerves or by tachykinin antagonists, but it was reduced by the 5-hydroxytryptamine antagonist methysergide. The inhibitory effect of SJW extract on acetylcholine-induced contractions was reduced by the sarcoplasmic reticulum Ca²⁺-ATPase inhibitor cyclopiazonic acid, but not by the L-type Ca²⁺ channel blocker nifedipine or by methysergide. Among the chemical constituents of SJW extract tested, hyperforin and, to a lesser extent, the flavonoids kaempferol and quercitrin, inhibited acetylcholine-induced contractions. It is concluded that SJW has a direct inhibitory effect on smooth muscle and could also possibly modulate gastric neurotransmission. If extended to humans, the inhibitory effect of SJW extract on gastric emptying in vivo could contribute, at least in part, to the clinical pharmacokinetic interactions between conventional medicines and this herbal antidepressant.     

Evaluation of oxidative stress via protein expression of glutathione S-transferase and cytochrome p450 (CYP450) ısoenzymes in psoriasis vulgaris patients treated with methotrexate

Introduction: Oxidative stress is the imbalance between oxidant-antioxidant systems and may play a major role in the psoriasis pathogenesis. Cytochrome (CYP) is a family of enzymes that are responsible for the metabolism of various endogenous and exogenous substances such as drug metabolism. Most importantly, the antioxidant system is the glutathione S-transferases (GST), which decrease oxidative stress by reducing oxidative products.

Aim: We aimed to evaluate the expressions of isoenzymes of GST and CYP families and the beneficial role of metotrexate (MTX) in this process.

Material and methods: This study included 21 patients with psoriasis and 22 healthy subjects. We treated all the patients with 10–15?mg/week of MTX for minimum 12?weeks. Expressions of GST and CYP enzymes were assessed by immunohistochemical staining.

Results: GSTK1, GSTM1 and GSTT1 expressions were significantly higher in the psoriasis tissues than in the control tissues (p?p?p?p?p?p?p?Conclusion: We found a significant increase in the tissue levels of, either expression of GST, or CYP, which has important role in drug metabolism and oxidative stress. MTX treatment resulted in marked clinical improvement, yet we found that MTX did not have any significant effect on these parameters. CYP2E1 is especially the most important enzyme for MTX metabolism since it is the primarily responsible of the toxic metabolism of various drugs. The other experimental studies involving greater number of patients and other different drug are needed to enlighten the role of oxidant and antioxidant systems and the other possible mechanisms for the pathogenesis of psoriasis.     

Interaction between a commercially available St. John’s wort product (Movina) and atorvastatin in patients with hypercholesterolemia

Objective The aim of this study was to assess the effect of treatment with a St. John’s wort product (Movina) on cholesterol [total cholesterol, low-density lipoprotein (LDL) cholesterol and high-density lipoprotein (HDL) cholesterol] and triglyceride levels in patients with hypercholesterolemia on treatment with a stable dose of atorvastatin in a controlled, randomised, open, crossover interaction study. Methods Sixteen patients with hypercholesterolemia treated with a stable dose of atorvastatin (10–40 mg/daily) for at least 3 months were treated with Movina one tablet (containing 300 mg of hypericum perforatum) twice daily and control (a commercially available multivitamin tablet Vitamineral). After a run-in period of 4 weeks, patients were randomised to treatment with either Movina or control for 4 weeks in a crossover design. The atorvastatin dose was kept unchanged during the study period (12 weeks), and assessments of total cholesterol, HDL cholesterol, LDL cholesterol and triglycerides were performed in the morning with the patients in the fasting condition. The difference between control and active treatment in LDL cholesterol after 4 weeks of treatment was the primary endpoint. Results All patients completed the study. The St. John’s wort product significantly increased the serum level of LDL cholesterol compared with control (2.66 mmol/l compared with 2.34 mmol/l, p = 0.004). A significant increase in total cholesterol was also observed (5,10 mmol/l compared with 4.78 mmol/l, p = 0.02). No statistically significant change was observed in HDL cholesterol (1.59 mmol/l and 1.56 mmol/l, p = 0.49) or in triglycerides (1.87 mmol/l and 1.94 mmol/l, p = 0.60). No product-related side effects were reported Conclusion An interaction was observed between the studied St.-John’s-wort-containing product and atorvastatin. Physicians and patients should be aware of this interaction and if treatment with a St. John’s wort product is considered necessary, then there may be a need for increasing the dose of atorvastatin.     

Inhibition of cytochrome P450 and uridine 5′-diphospho-glucuronosyltransferases by MAM-2201 in human liver microsomes

MAM-2201, a synthetic cannabinoid, is a potent agonist of the cannabinoid receptors and is increasingly used as an illicit recreational drug. The inhibitory effects of MAM-2201 on major drug-metabolizing enzymes such as cytochrome P450s (CYPs) and uridine 5′-diphospho-glucuronosyltransferases (UGTs) have not yet been investigated although it is widely abused, sometimes in combination with other drugs. We evaluated the inhibitory effects of MAM-2201 on eight major human CYPs (CYPs 1A2, 2A6, 2B6, 2C8, 2C9, 2C19, 2D6, and 3A4) and six UGTs (UGTs 1A1, 1A3, 1A4, 1A6, 1A9, and 2B7) of pooled human liver microsomes; we thus explored potential MAM-2201-induced drug interactions. MAM-2201 potently inhibited CYP2C9-catalyzed diclofenac 4′-hydroxylation, CYP3A4-catalyzed midazolam 1′-hydroxylation, and UGT1A3-catalyzed chenodeoxycholic acid 24-acyl-glucuronidation, with K _i values of 5.6, 5.4 and 5.0 µM, respectively. MAM-2201 exhibited mechanism-based inhibition of CYP2C8-catalyzed amodiaquine N-de-ethylation with K _i and k _inact values of 1.0 µM and 0.0738 min^?1, respectively. In human liver microsomes, MAM-2201 (50 µM) negligibly inhibited CYP1A2, CYP2A6, CYP2B6, CYP2C19, CYP2D6, UGT1A1, UGT1A4, UGT1A6, UGT1A9, and UGT2B7. Based on these in vitro results, we conclude that MAM-2201 has the potential to trigger in vivo pharmacokinetic drug interactions when co-administered with substrates of CYP2C8, CYP2C9, CYP3A4, and UGT1A3.     

Increased vulnerability to β-cell destruction and diabetes in mice lacking NAD(P)H:quinone oxidoreductase 1

NAD(P)H:quinone oxidoreductase 1 (NQO1) has been known to protect cells against stressors, including the diabetogenic reagent streptozotocin (STZ). The present study demonstrated that NQO1 deficiency resulted in increased pancreatic β-cell death induced by multiple low dose of STZ (MLDS) injections. NQO1 knockout (KO) mice showed hyperglycemia, body weight loss, impaired glucose clearance rate and a lower plasma insulin level after MLDS treatment. Moreover, β-cell mass and pancreatic insulin content were significantly lower in KO mice than in wild-type (WT) mice after MLDS treatment. Five days after the first STZ treatment, the islets of KO mice had substantially more TUNEL-positive β-cells than those of WT mice, but there was no difference in the regeneration of β-cells between KO mice and WT mice. At the same time, MLDS-treated KO mice showed significantly increased apoptotic markers in β-cells, including cleaved caspase 3, Smac/DIABLO and AIF (apoptosis inducing factor) in the cytoplasm. These results suggest that mice deficient in NQO1 are vulnerable to MLDS-induced β-cell destruction and diabetes, caused by increase of β-cell apoptosis in pancreas.     

Variability in PXR-mediated induction of CYP3A4 by commercial preparations and dry extracts of St. John’s wort

St. John’s wort (SJW, Hypericum perforatum) is a well-tolerated herbal medicine widely used for the treatment of mild and moderate depressions. In the last 5 years, SJW has been implicated in drug interactions, which are largely mediated by the induction of the drug metabolizing enzymes, especially CYP3A4. There is still some controversy regarding the exact mechanism of induction and the identity of the SJW constituents involved. We investigated in LS174T cells the induction of CYP3A4 by ten SJW extracts, six commercial preparations, and the purified SJW constituent hyperforin. The content of hyperforin among the commercial preparations of SJW varied 62-fold (range 0.49–30.57 mg/dose). The CYP3A4 induction was mediated by PXR, but not by CAR. The magnitude of the induction correlated statistically significantly with the content of hyperforin in commercial SJW preparations (R = 0.87, p = 0.004) and in dry extracts (R = 0.65, p = 0.03), but not with their content of flavonoids or hypericin. Most of the CYP3A4 induction response occurred in the hyperforin range encountered in the blood of patients treated with SJW preparations. A temperature-induced decrease in the hyperforin content of a selected dry SJW extract abolished the induction of CYP3A4. In conclusion, commercial SJW preparations still exhibit an enormous variability in CYP3A4 induction, which is mediated by hyperforin and PXR. SJW preparations with lower hyperforin content should reduce the frequency of clinical interactions involving this herbal drug. This work was partly funded by the Deutsche Forschungsgemeinschaft (DFG) grant WO505/2-2.     

St John’s wort extract (Ze 117) does not alter the pharmacokinetics of a low-dose oral contraceptive

Purpose

St John’s wort (Hypericum perforatum) is an herbal remedy that is widely used in the treatment of depression. Recent clinical data have demonstrated that St John’s wort extracts interfere with the action of various drugs and possibly also with combined oral contraceptives. Therefore, we investigated the effects of a St John’s wort extract (Ze 117) with low hyperforin content on the pharmacokinetics of ethinylestradiol and 3-ketodesogestrel.

Method

Sixteen healthy female volunteers, who had taken a low-dose oral contraceptive (Lovelle contains 0.02 mg ethinylestradiol + 0.15 mg desogestrel) for at least 3 months, participated in the study. Pharmacokinetic data (AUC, C_max, t_max) were determined the day before (reference) and after (test) a 14-day period of Ze 117 intake (250 mg twice daily).

Results

Before the co-administration of Ze 117 on day 7, the geometric mean (geometric coefficient of variation) for the AUC_0–24 of ethinylestradiol was 152.53 pg·h/ml (87.39%) and after co-administration on day 21 it was 196.57 pg·h/ml (78.14%). The respective values for ketodesogestrel were 36.37 pg·h/ml (34.18%) and 41.12 pg·h/ml (34.36%). The mean of individual ratios (reference-to-test) of log-transformed AUC values (90% confidence interval) were 0.951 (0.915–0.986) for ethinylestradiol and 0.968 (0.944–0.992) for ketodesogestrel indicating a small loss in bioavilability, but bioequivalence nevertheless.

Conclusion

These results indicate that the recommended dose of the hypericum extract Ze117, which has a low hyperforin content, does not interact with the pharmacokinetics of the hormonal components of the low-dose oral contraceptive.

     

The extent of induction of CYP3A by St. John’s wort varies among products and is linked to hyperforin dose

Objective Induction of CYP3A by St. John’s wort (SJW) extracts with high hyperforin (HYF) content is well described. Since SJW products vary in the amount of HYF and other main constituents, the aim of the study was to evaluate the effect on CYP3A function of SJW preparations with a range from very low to high HYF content. Methods Forty-two male, healthy volunteers were randomized into six parallel SJW medication groups with varying composition especially with regard to HYF content. Midazolam plasma concentration profiles were characterized after a single oral dose of 7.5 mg midazolam on the day before and on the 14th day of SJW medication. Results All SJW preparations tested resulted in a decrease in midazolam AUC, although the extent of the effect differed. The extract LI 160 (HYF 41 mg/day) decreased midazolam AUC_0–12h by 79.4% (95% CI −88.6; −70.1), which was significantly greater than the effect by any other medication (p<0.05). SJW powder tablets 2.7 g/day (HYF 12 mg/day) resulted in a midazolam AUC_0–12h decrease of 47.9% (95% CI −59.7;−36.2), while 2.7 g/day SJW powder tablets that were almost devoid of HYF (0.13 mg/day) reduced midazolam AUC_0–12h by only 21.1% (95% CI −33.9; −8.3). Considering all six SJW medications tested, the extent of midazolam AUC decrease correlated significantly with increasing HYF dose (r=−0.765, p<0.001), but not with hypericin dose (r=−0.067; p=0.673). Conclusion The extent of induction of CYP3A varies among St. John’s wort products and depends on hyperforin dose. The study was presented in part at the 2005 Annual Meeting of the American Society for Clinical Pharmacology and Therapeutics, Orlando, Florida, 2–6 March 2005. The study was started after approval by the ethics committee of the University of Rostock and was performed according to the national laws of Germany.     

Clinical risks of St John’s Wort (Hypericum perforatum) co-administration

Introduction: St. John’s wort (SJW) is a common medicinal herb used for the treatment of mild to moderate depression. Hyperforin, one of the chief components of SJW, plays an important role in the induction of cytochrome P450 enzymes (CYP) and P-glycoprotein transporter (P-gp), and therefore, affects the pharmacokinetics of various drugs. There are several clinical studies demonstrating the interaction of SJW with the metabolism of conventional drugs which may cause life-threatening events.

Areas covered: This review focuses on human studies that have evaluated pharmacokinetic alterations of conventional drugs in concomitant use with different SJW preparations.

Expert opinion: SJW preparations have demonstrated clinically important interactions with several classes of conventional drugs such as immunosuppressants, anticancer agents, cardiovascular drugs, oral contraceptives, and lipid lowering agents that caused life-threatening events in several cases. The patient information label on the SJW products should provide enough information regarding the possible risk of interaction. Hyperforin seems to be the major ingredient responsible for CYP and P-gp inducing activity of SJW; thus, hyperforin-free products may be future candidates to decrease SJW’s drug interactions.     

St. John’s Wort Modulates the Toxicities and Pharmacokinetics of CPT-11 (Irinotecan) in Rats

CPT-11 is a DNA topoisomerase I inhibitor for the therapy of colorectal cancer, whereas St. Johns Wort (Hypericum perforatum, SJW) is a widely used herbal anti-depressant. This study aimed to investigate the effects of co-administered SJW on the toxicities and pharmacokinetics of CPT-11 and the underlying mechanisms. The body weight loss, gastrointestinal and hematological toxicities induced by CPT-11, and the pharmacokinetic parameters of CPT-11 were evaluated in rats pretreated with SJW or vehicle. Rats treated with CPT-11 alone experienced rapid decrease in body weight, whereas co-administration of SJW with CPT-11 resulted in lesser body weight loss. The gastrointestinal and hematological toxicities following CPT-11 injection were both alleviated in the presence of SJW. The rat pharmacokinetics of both CPT-11 and its metabolite SN-38 were significantly altered in presence of SJW. In conclusion, co-administered SJW significantly ameliorated the toxicities induced by CPT-11. The protective effect of SJW may be partially due to pharmacokinetic interaction between CPT-11 and SJW.     

Comparison between recombinant P450s and human liver microsomes in the determination of cytochrome P450 Michaelis–Menten constants

1. Non-linear dose–exposure (supra-proportionality) occurs when plasma drug concentrations increase in a non-linear fashion with increasing dose. To predict the likelihood of this, an understanding is required of the K_M, which reflects a drug ability to saturate a specific enzyme involved in its metabolism.

2. This study assessed the accuracy of K_M and V_max determinations for compounds using a substrate-depletion approach with those determined using the product-formation approach, using both recombinant human cytochrome P450 (CYP) enzymes and human liver microsomes.

3. For the vast majority of the compounds studied, the K_M’s using recombinant CYPs and human liver microsomes in the two approaches predicted within two-fold. Further comparisons between the K_M and V_max-values were made between those measured using the product-formation approach and those estimated following simultaneous fitting of the Michaelis–Menten equation to all substrate depletion plots. In each case values were comparable.

4. In conclusion, the current study showed the substrate-depletion approach can be used to estimate K_M and V_max using both human liver microsomes and recombinant P450s. Estimation of these parameters during early discovery will aid in the understanding of dosages at which non-linearity may occur, but potentially aid predictions of likely clinical drug–drug interactions.

     

PKC-Mediated Potentiation of Morphine Analgesia by St. John’s Wort in Rodents and Humans

Our purpose was to combine the use of morphine with clinically available inhibitors of protein kinase C (PKC), finally potentiating morphine analgesia in humans. Thermal tests were performed in rodents and humans previously administered with acute or chronic morphine combined or not with increasing doses of the PKC-blocker St. John’s Wort (SJW) or its main component hypericin. Phosphorylation of the γ subunit of PKC enzyme was assayed by western blotting in the periaqueductal grey matter (PAG) from rodents co-administered with morphine and hypericin and was prevented in rodent PAG by SJW or hypericin co-administration with morphine, inducing a potentiation of morphine analgesia in thermal pain. The score of pain assessment in healthy volunteers were decreased by 40% when morphine was co-administered with SJW at a dose largely below those used to obtain an antidepressant or analgesic effect in both rodents and humans. The SJW/hypericin potentiating effect lasted in time and preserved morphine analgesia in tolerant mice. Our findings indicate that, in clinical practice, SJW could reduce the dose of morphine obtaining the same analgesic effect. Therefore, SJW and one of its main components, hypericin, appear ideal to potentiate morphine-induced analgesia.     

The effect of interferon-α on the expression of cytochrome P450 3A4 in human hepatoma cells

Esculetin (6,7-dihydroxy coumarin), is a potent antioxidant that is present in several plant species. The aim of this study was to investigate the mechanism of protection of esculetin in human hepatoma HepG2 cells against reactive oxygen species (ROS) induced by hydrogen peroxide. Cell viability, cell integrity, intracellular glutathione levels, generation of reactive oxygen species and expression of antioxidant enzymes were used as markers to measure cellular oxidative stress and response to ROS. The protective effect of esculetin was compared to a well-characterized chemoprotective compound quercetin. Pre-treatment of HepG2 cells with sub-lethal (10-25 μM) esculetin for 8 h prevented cell death and maintained cell integrity following exposure to 0.9 mM hydrogen peroxide. An increase in the generation of ROS following hydrogen peroxide treatment was significantly attenuated by 8 h pre-treatment with esculetin. In addition, esculetin ameliorated the decrease in intracellular glutathione caused by hydrogen peroxide exposure. Moreover, treatment with 25 μM esculetin for 8 h increased the expression of NAD(P)H: quinone oxidoreductase (NQO1) at both protein and mRNA levels significantly, by 12-fold and 15-fold, respectively. Esculetin treatment also increased nuclear accumulation of Nrf2 by 8-fold indicating that increased NQO1 expression is Nrf2-mediated. These results indicate that esculetin protects human hepatoma HepG2 cells from hydrogen peroxide induced oxidative injury and that this protection is provided through the induction of protective enzymes as part of an adaptive response mediated by Nrf2 nuclear accumulation.     

Effects of Ganoderma sterols （GS） on hepatic cytochrome P450 in BCG-induced immunological hepatic injury in BALB／c mice

AIM: To investigate effects of Ganoderma sterols (GS) isolated from Ganoderma lucidum (Leyss ex fr) Karst on hepatic cytochrome P450 in BCG-induced immunological hepatic injury in BALB/c mice and its possible mechanism. METHODS: Immunological liver injury was induced by one intravenous injection of BCG (125 mg/kg) in BALB/c mice. One week later, successiveintragastric administration of GS (20, 40, 80 mg/kg, per day) and     

Profiling of hypothalamic and hippocampal gene expression in chronically stressed rats treated with St. John’s wort extract (STW 3-VI) and fluoxetine

Rationale  

Hypericum perforatum L., known as St. John’s wort (SJW), is used as a phytotherapeutic agent for the treatment of mild to moderate forms of depression.     

The effects of sigma (σ1) receptor-selective ligands on muscarinic receptor antagonist-induced cognitive deficits in mice

Background and Purpose

Cognitive deficits in patients with Alzheimer''s disease, Parkinson''s disease, traumatic brain injury and stroke often involve alterations in cholinergic signalling. Currently available therapeutic drugs provide only symptomatic relief. Therefore, novel therapeutic strategies are needed to retard and/or arrest the progressive loss of memory.

Experimental Approach

Scopolamine-induced memory impairment provides a rapid and reversible phenotypic screening paradigm for cognition enhancement drug discovery. Male C57BL/6J mice given scopolamine (1 mg·kg⁻¹) were used to evaluate the ability of LS-1–137, a novel sigma (σ1) receptor-selective agonist, to improve the cognitive deficits associated with muscarinic antagonist administration.

Key Results

LS-1–137 is a high-affinity (K_i = 3.2 nM) σ1 receptor agonist that is 80-fold selective for σ1, compared with σ2 receptors. LS-1–137 binds with low affinity at D2-like (D2, D3 and D4) dopamine and muscarinic receptors. LS-1–137 was found to partially reverse the learning deficits associated with scopolamine administration using a water maze test and an active avoidance task. LS-1–137 treatment was also found to trigger the release of brain-derived neurotrophic factor from rat astrocytes.

Conclusions and Implications

The σ1 receptor-selective compound LS-1–137 may represent a novel candidate cognitive enhancer for the treatment of muscarinic receptor-dependent cognitive deficits.