Estrogenic and serotonergic butenolides from the leaves of Piper hispidum Swingle (Piperaceae)

Ethnopharmacological relevance

Our previous work has demonstrated that several plants in the Piperaceae family are commonly used by the Q’eqchi Maya of Livingston, Guatemala to treat amenorrhea, dysmenorrhea, and pain. Extracts of Piper hispidum Swingle (Piperaceae), bound to the estrogen (ER) and serotonin (5-HT7) receptors.

Aim of the study

To investigate the estrogenic and serotonergic activities of Piper hispidum extracts in functionalized assays, identify the active chemical constituents in the leaf extract, and test these compounds as agonists or antagonists of ER and 5-HT7.

Materials and methods

The effects of the Piper hispidum leaf extracts were investigated in estrogen reporter gene and endogenous gene assays in MCF-7 cells to determine if the extracts acted as an estrogen agonist or antagonist. In addition, the active compounds were isolated using ER- and 5-HT7 receptor bioassay-guided fractionation. The structures of the purified compounds were identified using high-resolution LC–MS and NMR spectroscopic methods. The ER- and 5-HT7-agonist effects of the purified chemical constituents were tested in a 2ERE-reporter gene assay in MCF-7 cells and in serotonin binding and functionalized assays.

Results

Three butenolides including one new compound (1) were isolated from the leaves of Piper hispidum, and their structures were determined. Compound 1 bound to the serotonin receptor 5-HT₇ with IC₅₀ values of 16.1 and 8.3 μM, respectively, and using GTP shift assays, Compound 1 was found to be a partial agonist of the 5-HT₇ receptor. The Piper hispidum leaf extracts, as well as Compounds 2 and 3 enhanced the expression of estrogen responsive reporter and endogenous genes in MCF-7 cells, demonstrating estrogen agonist effects.

Conclusions

Extracts of Piper hispidum act as agonists of the ER and 5-HT₇ receptors. Compound 1, a new natural product, identified as 9,10-methylenedioxy-5,6-Z-fadyenolide, was isolated as the 5-HT₇ agonist. Compounds 2 and 3 are reported for the first time in Piper hispidum, and identified as the estrogen agonists. No inhibition of CYP450 was observed for any of these compounds in concentrations up to 1 μM. These activities are consistent with the Q’eqchi traditional use of the plant for the treatment of disorders associated with the female reproductive cycle.     

Decreased GABA receptor in the striatum and spatial recognition memory deficit in epileptic rats: Effect of Bacopa monnieri and bacoside-A

Aim of the study

Gamma-aminobutyric acid A receptors are the principal mediators of synaptic inhibition in striatal neurons and play an important role in preventing the spreading of seizures through the striatum. In the present study, effect of Bacopa monnieri (L.) Pennel and its active component bacoside-A on spatial recognition memory deficit and alterations of GABA receptor in the striatum of epileptic rats were investigated.

Materials and methods

Total GABA and GABA_A receptor numbers in the control and epileptic rats were evaluated using [³H]GABA and [³H]bicuculline binding. GABA_Aα1, GABA_Aα5, GABA_Aγ3 and GABA_Aδ gene expressions were studied. Behavioral performance was assed using Y-maze.

Results

Scatchard analysis of [³H]GABA and [³H]bicuculline in the striatum of epileptic rats showed significant decrease in B_max compared to control. Real-Time PCR amplification of GABA_A receptor subunits such as GABA_Aα1, GABA_Aα5 and GABA_Aδ, were down regulated (p < 0.001) in the striatum of epileptic rats compared to control. Epileptic rats have deficit in Y-maze performance. Bacopa monnieri and bacoside-A treatment reversed these changes to near control.

Conclusion

Our results suggest that decreased GABA receptors in the striatum have an important role in epilepsy associated motor learning deficits and Bacopa monnieri and bacoside-A has a beneficial effect in the management of epilepsy.     

An aqueous extract of Poncirus fructus activates the prokinetic activity of 5-HT receptor subtype 4 without hERG interaction

Aim of the study

Poncirus fructus (PF) - also known as the dried, immature fruit of Poncirus trifoliata (L.) Raf. (Rutaceae) - is a natural substance that has long been used for various gastrointestinal disorders in eastern Asia. An aqueous extract of PF (PF-W) has particularly potent gastroprokinetic effects, but its molecular mechanism was not well understood. Identification of the underlying prokinetic mechanism of PF-W was pursued in the present study.

Materials and methods

Changes in in vitro cAMP levels and in vivo intestinal transit rate (ITR) caused by PF-W were measured after pretreatment with GR125487, an antagonist for serotonin receptor subtype 4 (5-HT4R). An [³H] astemizole binding assay and electrophysiology experiments were performed to determine if PF-W has any interaction with the human ether-à-go-go related gene (hERG) potassium channel.

Results

PF-W induced an increase in intracellular cAMP in 5-HT4R-expressing HEK293T cells, indicating that PF-W does activate 5-HT4R. Moreover, pretreatment with GR125487 successfully blocked the increase, suggesting that the response was 5-HT4R-specific. More importantly, pretreatment of GR125487 in rats inhibited the elevation of ITR by PF-W, indicating that the prokinetic effect of PF-W was indeed exerted via 5-HT4R. On the other hand, both [³H]-astemizole binding assay and electrophysiological experiments revealed that PF-W did not interfere at all with the hERG channel.

Conclusion

It was found that PF-W exerts its prokinetic activity through a 5-HT4R-mediated pathway, with no interaction with hERG channels. Therefore, PF-W is a good candidate that might be developed as a prokinetic agent with fewer expected cardiac side effects.     

Anxiolytic effect of a herbal medicine, yokukansan, in aged rats: Involvement of serotonergic and dopaminergic transmissions in the prefrontal cortex

Aim of the study

Aging is thought to affect emotions including anxiety, and a herbal medicine, yokukansan (YKS), is used to treat emotional disturbances associated with age-related neurodegenerative disorders such as Alzheimer's disease, but its pharmacological properties have not been fully understood. The present study was designed to examine whether YKS improves age-related anxiety using F344/N aged rats. Moreover, the effects of YKS on liver function were examined.

Materials and methods

YKS was administered to 21-month-old aged rats for 3 months. Locomotor activity of young control (4 months old), aged control (24 months old), and YKS-treated aged rats was examined, and the anxiety-related responses of these animals were evaluated by counting the number of excrements during locomotor activity measurement and in the elevated plus-maze test. The extracellular concentrations of serotonin and dopamine in the prefrontal cortex (PFC) were also measured using a microdialysis technique. Moreover, concentrations of aspartate aminotransferase (AST), alanine aminotransferase (ALT), and ammonia (NH₃) in plasma were measured.

Results

Although locomotor activity did not change among any experimental groups, the number of excrements was significantly increased in aged rats compared to young rats, and this increase was significantly improved by YKS treatment. Aged rats also showed significant decreases in time and frequency in the open arm of the elevated plus-maze, and these decreases were significantly improved by YKS treatment. Extracellular concentrations of serotonin and dopamine in the aged PFC were significantly decreased; serotonin was increased over the level of young rats and dopamine was partially improved by YKS treatment, respectively. In addition, YKS improved age-related increase in NH₃ concentration, but did not affect AST and ALT.

Conclusions

YKS has improving activity for age-related increased anxiety and enhances serotonergic and dopaminergic transmissions in the aged PFC. These mechanisms provide information important for the treatment of anxiety in the elderly. Furthermore, the present data confirm partially the Kampo concept “liver disease”.     

Pharmacological screening of Malian medicinal plants used against epilepsy and convulsions

Ethnopharmacological relevance

Several medicinal plants are used in Mali to treat epilepsy and convulsions. So far, no studies have investigated the pharmacological effect of these plants.

Aims

The aim of this study was to investigate the in vitro and in vivo antiepileptic potential of the ethanolic extracts of 11 Malian medicinal plants.

Materials and methods

The extracts were screened for antiepileptic properties in the mouse cortical wedge preparation and in the [³H]-flumazenil binding assay. Two of the plant extracts were investigated for anticonvulsive properties in the pentylenetetrazol (PTZ) kindling model in mice. Possible side effects on motor impairment were evaluated using the rota-rod test.

Results

Extracts of 10 of the 11 medicinal plants showed affinity to the benzodiazepine binding site on the GABA_A receptor. Seven of the 11 extracts inhibited the spontaneous discharges (SEDs) in the mouse cortical wedge preparation, with the extracts of Flueggea virosa and Psorospermum senegalense being the most potent. However, when tested for in vivo anticonvulsive properties these two extracts failed to show any effect on PTZ-induced seizures in mice.

Conclusions

The pharmacological screening of the ethanolic extracts of 11 Malian medicinal plants in vitro lead to the identification of several extracts with potential anticonvulsant properties.     

Effects of South African traditional medicine in animal models for depression

Ethnopharmacological relevance

The four South African medicinal plants Agapanthus campanulatus (AC), Boophone distica (BD), Mondia whitei (MW) and Xysmalobium undulatum (XU) are used in traditional medicine to treat depression.

Aim

To evaluate the effect of ethanolic extracts of the plants in models for depression.

Materials and methods

The extracts were screened for affinity for the serotonin transporter (SERT) in the [³H]-citalopram-binding assay. The inhibitory potency of the extracts towards the SERT, the noradrenalin transporter (NAT) and the dopamine transporter (DAT) were determined in a functional uptake inhibition assay. Antidepressant-like effects of the extracts were investigated using the tail suspension test (TST) and the forced swim test in both rats (rFST) and mice (mFST).

Results

All four plants showed affinity for SERT in the binding assay. AC and BD showed functional inhibition of SERT, NAT and DAT, MW affected SERT while XU showed no effect. BD showed significant effect in the TST and in the mFST/rFST, AC showed significant effect in mFST, MW showed significant effect in the rFST and XU showed significant effect in the mFST.

Conclusion

In this study we have demonstrated the antidepressant activity of four South African medicinal plants in vitro and in vivo, supporting their rational use in traditional medicine.     

Effects of the hook of Uncaria rhynchophylla on neurotoxicity in the 6-hydroxydopamine model of Parkinson's disease

Ethnopharmacological relevance

While the hook of Uncaria rhynchophylla (URH) is a traditional herb used in northeast Asia for the treatment of Parkinson's disease (PD)-like symptoms such as tremor, it has not been experimentally evaluated in a PD model.

Aim of the study

We investigated the effects of URH on 6-hydroxydapamine (6-OHDA)-induced neurotoxicity in in vitro and in vivo models of PD.

Materials and methods

The cell viability, anti-oxidative activity, and anti-apoptotic activity of a water extract of URH (URE) were assessed using 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl-tetrazolium bromide, reactive oxygen species (ROS), total glutathione (GSH), and caspase-3 assays in PC12 cells stressed by 6-OHDA. We also investigated the behavioral recovery and dopaminergic neuron protection of URE using an apomorphine-induced rotation test and tyrosine hydroxylase immunohistochemistry in the hemi-parkinsonian rat model of the unilateral 6-OHDA lesion of the medial forebrain bundle.

Results

In PC12 cells, URE significantly reduced cell death and the generation of ROS, increased GSH levels, and inhibited caspase-3 activity induced by 6-OHDA. In 6-OHDA-lesioned rats, posttreatment with URE (5 mg/kg/day for 14 days) significantly reduced apomorphine-induced rotation, and it lowered dopaminergic neuronal loss in substantia nigra pars compacta.

Conclusions

URE possesses neuroprotective activity against 6-OHDA-induced toxicity through anti-oxidative and anti-apoptotic activities in PD models.     

Antidepressant-like effect of the ethanolic extract from Suanzaorenhehuan Formula in mice models of depression

Ethnopharmacological relevance

Suanzaorenhehuan Formula (SHF) is a Chinese herbal formula for the treatment of depression-like disorders. It contains four herbs: Semen Ziziphi spinosae, Cortex Albiziae, Radix Paeoniae Alba and Semen Platycladi. The present study is to investigate the antidepressant-like effect of the ethanolic extract of SHF and its possible mechanisms.

Materials and methods

Mouse models of depression including the tail suspension test (TST), forced swimming test (FST) and chronic unpredicted mild stress (CUMS) were used to evaluate the effects of SHF extract. The mechanisms were examined by measuring monoamine neurotransmitters in mice hippocampus and frontal cortex, testing monoamine oxidase enzyme (MAO) activities in brain of CUMS-exposed mice.

Results

After one-week treatment, SHF extract (50, 100 and 200 mg/kg) induced a significant decrease on immobility time in TST. After two-week treatment, SHF extract (50, 100 and 200 mg/kg) led to a reduction in the immobility period in TST and FST. The 5-HT levels in mice hippocampus were increased only after 200 mg/kg SHF extract treatment. The noradrenaline (NE) levels were increased after 200 mg/kg SHF extract treatment in mice hippocampus and frontal cortex. SHF extract (50, 100 and 200 mg/kg) significantly inhibited monoamine oxidase-A (MAO-A) and monoamine oxidase-B (MAO-B) after 21-day CUMS exposure.

Conclusion

These findings demonstrated that ethanolic SHF extract produced an antidepressant-like effect and the mechanism of action involves the serotonergic, noradrenergic and monoamine oxidase enzyme systems although underlying mechanism still remains to be further elucidated.     

Anxiolytic-like effects of acute and chronic treatment with Achillea millefolium L. extract

Ethnopharmacological relevance

Achillea millefolium L. (Asteraceae), known as yarrow (“mil folhas”), has been used as folk medicine for gastrointestinal disorders, inflammation, anxiety, and insomnia.

Aim

To evaluate the potential anxiolytic-like effect of hydroalcoholic extract of Achillea millefolium L. in animal models.

Methods

The present study evaluated the effects of the hydroalcoholic extract from the aerial parts of Achillea millefolium L. in mice subjected to the elevated plus-maze, marble-burying, and open-field tests. Additionally, the GABA_A/benzodiazepine (BDZ) mediation of the effects of Achillea millefolium was evaluated by pretreatment with the noncompetitive GABA_A receptor antagonist picrotoxin and the BDZ antagonist flumazenil and by [³H]-flunitrazepam binding to the BDZ site on the GABA_A receptor.

Results

Achillea millefolium exerted anxiolytic-like effects in the elevated plus-maze and marble-burying test after acute and chronic (25 days) administration at doses that did not alter locomotor activity. This behavioral profile was similar to diazepam. The effects of Achillea millefolium in the elevated plus-maze were not altered by picrotoxin pretreatment but were partially blocked by flumazenil. Furthermore, Achillea millefolium did not induce any changes in [³H]-flunitrazepam binding.

Conclusion

The results indicate that the orally administered hydroalcoholic extract of Achillea millefolium L. exerted anxiolytic-like effects that likely were not mediated by GABA_A/BDZ neurotransmission and did not present tolerance after short-term, repeated administration.     

Interactions of Magnolia and Ziziphus extracts with selected central nervous system receptors

Ethnopharmacological relevance

Magnolia officinalis Rehder and Wilson [Magnoliaceae] bark and Ziziphus spinosa (Buhge) Hu ex. Chen. [Fam. Rhamnaceae] seed have a history of use in traditional Asian medicine for mild anxiety, nervousness and sleep-related problems.

Aim of the study

To identify pharmacological targets, extracts of Magnolia officinalis (ME), Ziziphus spinosa (ZE), and a proprietary fixed combination (MZE) were tested for affinity with central nervous system receptors associated with relaxation and sleep.

Methods

In vitro radioligand binding and cellular functional assays were conducted on: adenosine A₁, dopamine (transporter, D₁, D_2S, D₃, D_4.4 and D₅), serotonin (transporter, 5-HT_1A, 5-HT_1B, 5-HT_4e, 5-HT₆ and 5-HT₇) and the GABA benzodiazepine receptor.

Results

Interactions were demonstrated with the adenosine A₁ receptor, dopamine transporter and dopamine D₅ receptor (antagonist activity), serotonin receptors (5-HT_1B and 5-HT₆ antagonist activity) and the GABA benzodiazepine receptor at a concentration of 100 μg/ml or lower. ME had an affinity with adenosine A₁ (K_i of 9.2 ± 1.1 μg/ml) and potentiated the GABA activated chloride current at the benzodiazepine subunits of the GABA receptor (maximum effect at 50 μg/ml). ME had a modest antagonist action with 5-HT₆ and ZE with the 5-HT_1B receptor.

Conclusion

The interactions in the receptor binding models are consistent with the traditional anxiolytic and sleep-inducing activities of Magnolia officinalis bark and Ziziphus spinosa seed.     

Glycyrrhiza and Uncaria Hook contribute to protective effect of traditional Japanese medicine yokukansan against amyloid β oligomer-induced neuronal death

Ethnopharmacological relevance

Yokukansan, a traditional Japanese (Kampo) medicine, composed of seven medicinal herbs has been traditionally used to treat neurosis, insomnia, and night crying and irritability in children. Recently, this medicine has been reported to improve the behavioral and psychological symptoms of dementia (BPSD) that often become problematic in patients with Alzheimer's disease (AD).

Aim of the study

Amyloid β (Aβ) oligomers, which are extremely toxic to neurons, are involved in neurodegeneration in AD. In animals, yokukansan has been proven to improve memory impairments and BPSD-like behavior in transgenic mice overexpressing amyloid precursor protein and mice intracerebroventricularly injected with Aβ oligomers. These results suggest that yokukansan is potentially able to reduce the neurotoxicity of Aβ oligomers. Therefore, the present study aimed to explore the improving effects brought by yokukansan that consists of seven herbs for Aβ oligomer-induced neurotoxicity in vitro and to identify the candidate herbs in yokukansan's action.

Materials and methods

Primary cultured rat cortical neurons were used. Neurotoxicity induced by Aβ oligomers (3 µM) and improving effects of yokukansan (300–1000 µg/mL) and its constituent herbs were evaluated in MTT assay, DNA fragmentation analysis, and electron microscopic analysis at 48 h after treatment with Aβ oligomers and drugs. Moreover, changes in expression of genes related to endoplasmic reticulum (ER) stress and in caspase-3 activity that is the enzyme closely related to apoptosis were analyzed to investigate the underlying mechanisms.

Results

Yokukansan ameliorated Aβ oligomer-induced neuronal damage in a dose-dependent manner in the MTT assay. This drug also suppressed DNA fragmentation caused by Aβ oligomers. Electron microscopic analysis suggested that yokukansan reduced karyopyknosis and the expansion of rough ER caused by Aβ oligomers. However, neither Aβ oligomers nor yokukansan affected the mRNA expression of any ER stress-related genes, including CHOP and GRP78. On the other hand, yokukansan dose-dependently suppressed Aβ oligomer-induced activation of caspase-3. Among the seven constituents of yokukansan, Glycyrrhiza and Uncaria Hook (60–200 µg/mL) suppressed Aβ oligomer-induced neuronal damage, DNA fragmentation, karyopyknosis, and caspase-3 activation to almost the same extent as yokukansan.

Conclusions

The present results suggest that yokukansan possesses an ameliorative effect against Aβ oligomer-induced neuronal apoptosis through the suppression of caspase-3 activation. Glycyrrhiza and Uncaria Hook may, at least in part, contribute to the neuroprotective effect of yokukansan. These mechanisms may underlie the improving effects of yokukansan on memory impairment and BPSD-like behaviors induced by Aβ oligomers.     

Effect of tonifying liver and kidney-essence herbs on expression of Nogo-A and p75NTR in cerebral ischemic stroke rats model

Objective

To observe the effect of tonifying liver and kidney-essence herbs on expression of a nerve regeneration inhibitor, Nogo for neuron A (Nogo-A), and its associated signaling molecule, low-affinity neurotrophin receptor p75 (p75^NTR), in rats with cerebral ischemic stroke (CIS), with the aim of exploring the possible mechanism of tonifying liver and kidney-essence herbs in recovery following injury to the central nervous system.

Methods

A cerebral ischemic stroke model in SD rats was established with the suture-occlusion method. Successful model rats were divided into placebo and herb groups at random; sham-operated and control groups were set up simultaneously. Each of these groups was divided into six subgroups at random. Expression of Nogo-A and p75^NTR was evaluated with immunofluorescence microscopy at days 3, and weeks1, 2, 3, 4 and 8 after administration.

Results

Tonifying liver and kidney-essence herbs suppressed the expression of Nogo-A and p75^NTR (P<0.05 and P<0.01, respectively).

Conclusion

Suppressing the expression of Nogo-A and p75^NTR is possibly one of the mechanisms underlying the ability of tonifying liver and kidney-essence herbs to promote recovery of the injured central nervous system.     

Inhibitory effects of Geijigajakyak-Tang on trinitrobenzene sulfonic acid-induced colitis

Aim of the study

Water extract of Geijigajakyak-Tang (GJT) consisting of five crude drugs [dried root of P. lactiflora Peony (Paeoniaceae), dried trunk bark of C. cassia Blume (Lauraceae), seed of Z. jujube var. inermis Mill (Rhamnaceae), fresh root of Z. officinale Rocoe (Zingiberaceae) and dried trunk bark of G. uralensis Fish (Leguminosae)] is a folk medicine used for the treatment of chronic colitis. This study was designed to further elucidate the effect of GJT on 2,4,6-trinitrobenzene sulfonic acid (TNBS)-induced colitis in rats.

Materials and methods

GJT orally given to mice before and after TNBS intoxication, and their clinical and morphological changes, myeloperoxidase (MPO) activity and malondialdehyde (MDA) levels in colon tissues, were evaluated on Day 8 post-TNBS. Furthermore, the effect of six major constituents of individual herbs on ileum smooth muscle contraction and neutrophil chemotaxis was studied.

Results

GJT had a significant anti-inflammatory effect based on clinical and morphologic changes, MPO activity and MDA levels in colon tissues as compared with sham control. GJT and 5 major active constituents of individual herbs, paeoniflorin, cinnamaldehyde, jujuboside A, jujubogenin, and diammonium glycyrhhizinate significantly inhibited neutrophil chemotaxis. GJT significantly inhibited muscle contraction (IC₅₀; 2.10 ± 0.11 mg/ml), and 1,8-cineol has the most spasmolytic activity (IC₅₀; 0.10 ± 0.03 mg/ml).

Conclusion

GJT has significant anti-inflammatory effects on TNBS-induced colitis via inhibitions of smooth muscle contraction and neutrophil chemotaxis.     

Water extract of Rheum officinale Baill. induces apoptosis in human lung adenocarcinoma A549 and human breast cancer MCF-7 cell lines

Ethnopharmacological relevance

Rheum officinale Baill. (Da Huang) is one of the herbs commonly used in traditional Chinese medicine formulae against cancer. The traditional decoction is similar to the water extract used in the present study.

Aim of the study

The water extract of Da Huang was investigated to see if it possesses anticancer effects through apoptotic pathways.

Materials and methods

Human lung adenocarcinoma A549 and human breast cancer MCF-7 cell lines were treated with different concentrations of Da Huang water extract at different time intervals. Growth inhibition was detected by MTS [3-(4,5-dimethylthiazol-2-yl)-5-(3-carboxymethoxyphenyl)-2-(4-sulfophenyl)-2H-tetrazolium] and colony formation assays; apoptosis was detected by cell morphologic analysis, DNA fragmentation analysis and COMET assay.

Results

Da Huang water extract was found to have significant growth inhibitory effects on both A549 and MCF-7 cell lines with IC₅₀ values 620 ± 12.7 and 515 ± 10.1 μg/ml, respectively. Growth inhibitory effects were dose- and time-dependent. A significant decrease in cell number, DNA fragmentation and single DNA strand breakages were observed in the Da Huang water extract treated A549 and MCF-7 cells.

Conclusions

This suggests that the water extract of Da Huang exerts potential anticancer activity through growth inhibition and apoptosis on MCF-7 and A549 cells lines.     

Effect of Alkaloid-Free and Alkaloid-Rich preparations from Uncaria tomentosa bark on mitotic activity and chromosome morphology evaluated by Allium Test

Ethnopharmacological revelance

Uncaria tomentosa (Willd.) DC. is the most popular Peruvian plant, used in folk medicine for different purposes. It contains thousands of active compounds with great content of alkaloids.

Aim of study

Two different fractions of Alkaloid-Rich and Alkaloid-Free were researched on chromosome morphology, mitotic activity and phases indexes.

Materials and methods

Cells of Allium Test (meristematic cells of root tips) were incubated up to 24 h in different concentrations of Alkaloid-Free and Alkaloid-Rich fraction obtained from Uncaria tomentosa bark followed by 48 h of postincubation in water. The chromosome morphology was analyzed and the content of mitotic and phase indexes were done. Individual compounds, oxindole alkaloids, phenolic compounds and sugars were determined.

Results

In Alkaloid-Rich and Alkaloid-Free fractions (different in chemical composition) we observed condensation and contraction of chromosomes (more in Alkaloid-Rich) with retardation and/or inhibition of mitoses and changed mitotic phases. Postincubation reversed results in the highest concentration which was lethal (in mostly Alkaloid-Rich fraction).

Conclusions

Our studies indicate that different action can depend on different groups of active compounds in a preparation either containing alkaloids or not. Other fraction analysis may be useful in the future.     

Poncirus trifoliate fruit modulates pacemaker activity in interstitial cells of Cajal from the murine small intestine

Ethnopharmacological relevance

Poncirus fructus (PF) has been widely used as a traditional medicine in Eastern Asia, especially to ameliorate the symptoms of gastrointestinal (GI) disorders related to abnormal GI motility.

Aim of the study

Poncirus fructus (PF), also known as Poncirus trifoliata (L.) Raf. (Rutaceae), is widely used as a traditional medicine in Eastern Asia mainly to ameliorate the symptoms of gastrointestinal (GI) disorders related to abnormal GI motility. In a previous study, a methanol extract of PF was found to have particularly potent gastroprokinetic effects. Interstitial cells of Cajal (ICCs) are pacemaker cells in the gastrointestinal tract, but the action mechanisms of PF extract in mouse small intestinal ICCs have not been investigated. Therefore, in the present study, we investigated the effects of a methanol extract of PF (MPF) in mouse small intestinal ICCs. In addition, we sought to identify the receptors involved.

Materials and Methods

Enzymatic digestions were used to dissociate ICCs from small intestines. The whole-cell patch-clamp configuration was used to record potentials (current clamp) from cultured ICCs. In addition, we analyzed intracellular Ca²⁺ concentrations ([Ca²⁺]_i).

Results

MPF decreased the amplitudes of pacemaker potentials in ICCs, and depolarized resting membrane potentials in a concentration dependent manner. Y25130 (a 5-HT₃ receptor antagonist) and RS39604 (a 5-HT₄ receptor antagonist) blocked MPF-induced membrane depolarizations, whereas SB269970 (a 5-HT₇ receptor antagonist) did not. Pretreatment with Na⁺ or Ca²⁺-free solution or thapsigargin (a Ca²⁺-ATPase inhibitor in endoplasmic reticulum) abolished the generation of pacemaker potentials and suppressed MPF-induced activity. [Ca²⁺]_i analysis showed that MPF increased [Ca²⁺]_i. Furthermore, treatments with PD 98059, SB203580, or JNK II inhibitor blocked MPF-induced membrane depolarizations in ICCs.

Conclusion

These results suggest that MPF modulates pacemaker potentials through 5-HT₃ and 5-HT₄ receptor-mediated pathways via external Na⁺ and Ca²⁺ influx, and via Ca²⁺ release from internal stores in a mitogen-activated protein kinase dependent manner. The study shows MPF is a good candidate for the development of a gastroprokinetic agent. In view of the effects of MPF on ICCs, further research is required, particularly to identify the active compound(s) involved and to determine their action mechanisms.     

Vasodilatory effects of ethanol extract of Radix Paeoniae Rubra and its mechanism of action in the rat aorta

Ethnopharmacological relevance

Radix Paeoniae Rubra (RPR) is an important traditional Chinese medicine (TCM) commonly used in clinic for a long history in China. RPR is the radix of either Paeonia lactiflora Pall. or Paeonia veitchii Lynch. RPR has a wide variety of pharmacological actions such as anti-thrombus, anti-coagulation, and anti-atherosclerotic properties, protecting heart and liver. However, the mechanisms involved are to be defined.

Aim of the study

The aim of the present study was to define the effect of Paeonia lactiflora Pall. extracts on vascular tension and responsible mechanisms in rat thoracic aortic rings.

Materials and methods

Ethanol extract of Paeonia lactiflora Pall. (EPL) was examined for their vascular relaxant effects in isolated phenylephrine-precontracted rat thoracic aorta.

Results

EPL induced relaxation of the phenylephrine-precontracted aortic rings in a concentration-dependent manner. Vascular relaxation induced by EPL was significantly inhibited by removal of the endothelium or pretreatment of the rings with N^G-nitro-l-arginine methylester (l-NAME) or 1H-[1,2,4]-oxadiazolo-[4,3-α]-quinoxalin-1-one (ODQ). Extracellular Ca²⁺ depletion or diltiazem significantly attenuated EPL-induced vasorelaxation. Modulators of the store-operated Ca²⁺ entry (SOCE), thapsigargin, 2-aminoethyl diphenylborinate and Gd³⁺, and an inhibitor of Akt, wortmannin, markedly attenuated the EPL-induced vasorelaxation. Further, the EPL-induced vasorelaxation was significantly attenuated by pretreatment with tetraethylammonium, a non-selective K_Ca channels blocker, or glibenclamide, an ATP-sensitive K⁺ channels inhibitor, respectively. Inhibition of cyclooxygenases with indomethacin, and adrenergic and muscarinic receptors blockade had no effects on the EPL-induced vasorelaxation.

Conclusions

The present study suggests that EPL relaxes vascular smooth muscle via endothelium-dependent and Akt- and SOCE-eNOS-cGMP-mediated pathways through activation of both K_Ca and K_ATP channels and inhibition of L-type Ca²⁺ channels.     

Yokukansan, a kampo medicine, protects against glutamate cytotoxicity due to oxidative stress in PC12 cells

Aim of the study

Yokukansan is a traditional Japanese medicine consisted of seven medicinal herbs and has been used for treatment of neurosis, insomnia, and behavioral and psychological symptoms of dementia in Japan. The aim of the present study is to clarify the active compounds responsible for the protective effect of yokukansan against glutamate-induced cytotoxicity in PC12 cells.

Materials and methods

PC12 cells which is a tool for selective evaluation of test substances against oxidative stress was used in the present study. The cell survival rates or glutathione (GSH) levels were evaluated by a MTT reduction assay or GSH assay based on the GSH reductase enzymatic recycling method, respectively.

Results

Glutamate (1-17.5 mM) induced cell death of PC12 cells in a concentration- dependent manner. Yokukansan (125-500 μg/ml) inhibited the glutamate-induced PC12 cell death. When the effects of extracts of the seven constituent herbs in yokukansan on the cell death were examined, Uncaria thorn was found to have the highest potency in the protection. To clarify the active compounds in Uncaria thorn, the effects of seven alkaloids (rhynchophylline, isorhynchophylline, corynoxeine, isocorynoxeine, hirsutine, hirsuteine, and geissoschizine methyl ether) on the cell death were further examined. The protective effects were found in hirsutine, hirsuteine, and geissoschizine methyl ether, which also ameliorated the glutamate-induced decrease in GSH levels.

Conclusion

These results suggest that yokukansan protects against PC12 cell death induced by glutamate-mediated oxidative stress, i.e., reduction of intracellular GSH level, and the effect may be mainly attributed to a synergistic effect of the hirsutine, hirsuteine, and geissoschizine methyl ether in Uncaria thorn.     

Effect of Chinese herbs on CYP3A4 activity and expression in vitro

Ethnopharmacological relevance

Traditional Chinese Medicine (TCM) has become more popular among cancer patients in the Western world, who often use Chinese herbs as adjuvant therapy to reduce the adverse effects of conventional chemotherapy. However, pharmacokinetic (PK) interactions between Chinese herbs and anticancer drugs can occur and have dramatic consequences for these patients. Currently, only a few possible PK interactions between Chinese herbs and conventional Western drugs have been documented.

Aim of the study

Since the drug-metabolizing enzyme cytochrome P450 3A4 (CYP3A4) contributes to most of the PK interactions with (anticancer) drugs, the effect of four Chinese herbs (Oldenlandia diffusa, Codonopsis tangshen, Rehmannia glutinosa and Astragalus propinquus) on the activity and expression of CYP3A4 was investigated in vitro.

Materials and methods

Ethanol and water–ethanol extracts of the four Chinese herbs were prepared from raw material. CYP3A4 inhibition was assessed by the use of Supersomes^™ in a fluorescence assay. Furthermore, CYP3A4 induction was evaluated in a human pregnane X receptor (hPXR)-mediated CYP3A4 reporter gene assay and a quantitative real time PCR assay, both in human colon adenocarcinoma-derived LS180 cells (LS180).

Results

Extracts of Oldenlandia diffusa, Codonopsis tangshen, Rehmannia glutinosa and Astragalus propinquus inhibited CYP3A4 in human CYP3A4 Supersomes^™ (IC₅₀ values: 17–83 µg/mL). Oldenlandia diffusa and Rehmannia glutinosa significantly induced PXR-mediated CYP3A4 (p<0.001). Oldenlandia diffusa also significantly induced CYP3A4 mRNA levels (p<0.001 at 250 µg/mL).

Conclusions

Concomitant use of Oldenlandia diffusa and Rehmannia glutinosa could result in induction of CYP3A4, leading to a reduced efficacy of drugs that are CYP3A4 substrates and have a narrow therapeutic window. Because of the possible enhanced toxicity caused by CYP3A4 inhibition, clinical effects of CYP3A4 inhibition by Astragalus propinquus and Codonopsis tangshen must also be taken into account. In conclusion, herb–drug interactions between Chinese herbs and various CYP3A4 substrates can occur. Further research to investigate the clinical relevance of the interactions caused by Oldenlandia diffusa, Codonopsis tangshen, Rehmannia glutinosa and Astragalus propinquus is required.