Evaluation of the protective effects of alkaloids isolated from the hooks and stems of Uncaria sinensis on glutamate-induced neuronal death in cultured cerebellar granule cells from rats

Anti-inflammatory effects of rhynchophylline and isorhynchophylline in mouse N9 microglial cells and the molecular mechanism

Excessive production of nitric oxide (NO) and proinflammatory cytokines from activated microglia contributes to human neurodegenerative disorders. Our previous study demonstrated the potent inhibition of lipopolysaccharide (LPS)-induced NO production in rat primary microglial cells by rhynchophylline (RIN) and isorhynchophylline (IRN), a pair of isomeric alkaloids of Uncaria rhynchophylla (Miq.) Jacks. that has been used in China for centuries as a "cognitive enhancer" as well as to treat strokes. We further investigated whether RIN and IRN effectively suppress release of proinflammatory cytokines in LPS-activated microglial cells and the underling molecular mechanism for the inhibition of microglial activation. RIN and IRN concentration-dependently attenuated LPS-induced production of proinflammatory cytokines such as TNF-alpha and IL-1beta as well as NO in mouse N9 microglial cells, with IRN showing more potent inhibition of microglial activation. The western blotting analysis indicated that the potential molecular mechanism for RIN or IRN-mediated attenuation was implicated in suppressions of iNOS protein level, phosphorylation of ERK and p38 MAPKs, and degradation of IkappaBalpha. In addition, the differential regulation of the three signaling pathways by two isomers was shown. Our results suggest that RIN and IRN may be effective therapeutic candidates for use in the treatment of neurodegenerative diseases accompanied by microglial activation.

Yi-gan san as adjunctive therapy for treatment-resistant schizophrenia: an open-label study

BACKGROUND

Recent studies indicate that the traditional Japanese herbal medicine yi-gan san (YGS; yokukan-san in Japanese) may be safe and useful in treating behavioral and psychological symptoms in patients with dementia and borderline personality disorder. We aimed at evaluating both the efficacy and safety of YGS in patients with treatment-resistant schizophrenia.

METHODS

Thirty-four patients diagnosed with schizophrenia according to Diagnostic and Statistical Manual of Mental Disorders, Fourth Edition, (YGS-free) group (n = 25) and treated in a 4-week open-label study with YGS at an average daily dosage of 6.7 +/- 2.5 g (range, 2.5-7.5 g). Psychometric instruments used to assess efficacy included the Positive and Negative Syndrome Scale for Schizophrenia and the Drug-Induced Extrapyramidal Symptom Scale.

RESULTS

A significant decrease was observed at 2 weeks and at 4 weeks in each Positive and Negative Syndrome Scale for Schizophrenia subscale score in the YGS group, but this was not observed in the control group. However, the Drug-Induced Extrapyramidal Symptom Scale total score did not change in both groups.

CONCLUSIONS

In this open-label pilot study, patients treated with YGS showed a statistically significant reduction on clinician-rated scales. The present findings suggest that an adjunction of YGS might be effective for treatment-resistant schizophrenia.

Evidence for a role of 5-HT(1A) receptor on antinociceptive action from Geissospermum vellosii

ETHNOPHARMACOLOGICAL RELEVANCE

Geissospermum vellosii is a tree widely found throughout the Amazonic forest and frequently used by the native population for painful disorders.

AIM OF THE STUDY

The present study examined the antinociceptive effects of Geissospermum vellosii in behavioral models of nociception.

MATERIALS, METHODS AND RESULTS

Oral administration of crude extract of Geissospermum vellosii or its dichloromethane fraction (1-100 mg/kg) inhibited formalin-induced inflammatory nociception and acetic acid-induced visceral nociception. The antinociceptive effect of Geissospermum vellosii was unrelated with motor dysfunctions. Furthermore, the alkaloid 12-metoxy-1-methyl-aspidospermidine (0.001-1 mg/kg), isolated from the dichloromethane fraction, also produced antinociception. The antinociception caused by the dichloromethane fraction was significantly attenuated by pre-treatment of mice with p-chlorophenylalanine methyl ester (PCPA, an inhibitor of serotonin synthesis, 100 mg/kg once a day for 4 consecutive days) and WAY-100635 (a 5-HT(1A) receptor antagonist, 0.3 mg/kg). In contrast, dichloromethane fraction antinociception was not affected by pre-treatment of animals with ketanserin (a 5-HT(2) receptor antagonist, 0.3 mg/kg) or ondansetron (a 5-HT(3) receptor antagonist, 0.5 mg/kg).

CONCLUSIONS

Together, these results indicate that Geissospermum vellosii produces antinociception through an interaction with 5-HT(1A) receptors. Furthermore, the alkaloid 12-metoxy-1-methyl-aspidospermidine contributes to the antinociceptive properties reported for Geissospermum vellosii.

Traditional Chinese medicine on four patients with Huntington's disease

Four Huntington's disease (HD) patients were treated with traditional Chinese medicines Yi-Gan San (YGS) and Chaihu-Jia-Longgu-Muli Tan (CLMT) in a cross-over manner. Two patients took YGS for 8 weeks first, and after 4 weeks of washing out, they took CLMT for 8 weeks. Two other patients took these medicines in reverse order. All patients showed a decrease in the Unified Huntington's Disease Rating Scale-motor assessment (from 106.3 +/- 4.7 to 89.6 +/- 5.8 as mean +/- SD, P = 0.0004) by YGS treatment with no extrapiramidal symptoms or changes of cognition or ADL. Our study suggests a possibility of a new treatment for involuntary movements.

Rhynchophylline from Uncaria rhynchophylla functionally turns delayed rectifiers into A-Type K+ channels

Rhynchophylline (1), a neuroprotective agent isolated from the traditional Chinese medicinal herb Uncaria rhynchophylla, was shown to affect voltage-gated K(+) (Kv) channel slow inactivation in mouse neuroblastoma N2A cells. Extracellular 1 (30 microM) accelerated the slow decay of Kv currents and shifted the steady-state inactivation curve to the left. Intracellular dialysis of 1 did not accelerate the slow current decay, suggesting that this compound acts extracellularly. In addition, the percent blockage of Kv currents by this substance was independent of the degree of depolarization and the intracellular K(+) concentration. Therefore, 1 did not appear to directly block the outer channel pore, with the results obtained suggesting that it drastically accelerated Kv channel slow inactivation. Interestingly, 1 also shifted the activation curve to the left. This alkaloid also strongly accelerated slow inactivation and caused a left shift of the activation curve of Kv1.2 channels heterologously expressed in HEK293 cells. Thus, this compound functionally turned delayed rectifiers into A-type K(+) channels.

Neuroprotective effects of yokukansan, a traditional Japanese medicine, on glutamate-mediated excitotoxicity in cultured cells

To clarify the mechanism of yokukansan (TJ-54), a traditional Japanese medicine, against glutamate-mediated excitotoxicity, the effects of TJ-54 on glutamate uptake function were first examined using cultured rat cortical astrocytes. Under thiamine-deficient conditions, the uptake of glutamate into astrocytes, and the levels of proteins and mRNA expressions of glutamate aspartate transporter of astrocytes significantly decreased. These decreases were ameliorated in a dose-dependent manner by treatment with TJ-54 (100-700 microg/ml). The improvement of glutamate uptake with TJ-54 was completely blocked by the glutamate transporter inhibitor DL-threo-beta-hydroxyaspartic acid. Effects of TJ-54 on glutamate-induced neuronal death were next examined by using cultured PC12 cells as a model for neurons. Addition of 17.5 mM glutamate to the culture medium induced an approximately 50% cell death, as evaluated by the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assay. TJ-54 (1-1000 microg/ml) inhibited the cell death in a dose-dependent manner. Furthermore, competitive binding assays to glutamate receptors showed that TJ-54 bound potently to N-methyl-D-aspartate receptors, in particular, to its glutamate and glycine recognition sites. These results suggest that TJ-54 may exert a neuroprotective effect against glutamate-induced excitotoxicity not only by amelioration of dysfunction of astrocytes but also by direct protection of neuronal cells.

Neuroprotective effects of Yi-Gan San against beta amyloid-induced cytotoxicity on rat cortical neurons

INTRODUCTION

Recent clinical studies have demonstrated that Yi-Gan San (YGS, Yokukan-San in Japanese), a Chinese herbal medicine, alleviates various dementia-related symptoms. However, Chinese herbal medicines have rarely been investigated scientifically and the underlying mechanism of YGS remains uncertain. In this study, we investigated the effect of YGS on beta amyloid protein (Abeta)-induced cytotoxicity in a primary culture of rat cortical neurons.

METHODS

Cortical neurons prepared from rat embryos were exposed to Abeta in the presence or absence of YGS. The protective effect of YGS was measured as the % of control (unexposed neurons) by using MTT assay and LDH assay.

RESULTS

Abeta significantly decreased the number of surviving cortical neurons at a dose of 20 microM and higher. In the presence of 20 microM Abeta, YGS concentrations of 10(-5) g/L (W/V) and higher significantly increased the number of viable neurons.

CONCLUSION

Our study demonstrated a neuroprotective effect of Yi-Gan San against Abeta-induced cytotoxicity. Since according to traditional herbal medicine beliefs, YGS most likely exerts its clinical effects not through a single constituent but as a mixture of several herbal ingredients, the true mechanism of this neuroprotective action remains unclear. However, our results suggest that this Chinese herbal medicine might be a valuable treatment for clinical symptoms associated with dementia having fewer side effects and possible additional neuroprotective effects in the elderly.

Alkaloids from the leaves of Uncaria rhynchophylla and their inhibitory activity on NO production in lipopolysaccharide-activated microglia

Two new isomeric alkaloids, 18,19-dehydrocorynoxinic acid B (1) and 18,19-dehydrocorynoxinic acid (2), were isolated from the CHCl3 extract of the leaves of Uncaria rhynchophylla, together with four known rhynchophylline-type alkaloids, corynoxeine (3), isocorynoxeine (4), rhynchophylline (5), and isorhynchophylline (6), and an indole alkaloid glucoside, vincoside lactam (7). The structures of compounds 1 and 2 were elucidated by spectroscopic methods including UV, IR, HREIMS, 1D and 2D NMR, and CD experiments. The activity assay showed that compounds 3-6, with a C-16 carboxylic ester group, and 7 exhibited inhibitory activity on lipopolysaccharide (LPS)-induced NO release in primary cultured rat cortical microglia (IC 50: 13.7-19.0 microM). However, only weak inhibitory activity was observed for compounds 1 and 2, with a C-16 carboxylic acid group (IC 50: >100 microM).

Yi-gan san for the treatment of neuroleptic-induced tardive dyskinesia: an open-label study

BACKGROUND

Recent studies indicate that the traditional Japanese herbal medicine yi-gan san (YGS, yokukan-san in Japanese), a serotonin modulator, may be safe and useful in treating behavioral and psychological symptoms in dementia and borderline personality disorder patients. The authors examined the efficacy, tolerability, and safety of YGS in patients with tardive dyskinesia.

METHODS

Twenty-two patients with schizophrenia who had neuroleptic-induced tardive dyskinesia were given 7.5 g/day of YGS for 12 weeks in an open-label study.

RESULTS

Administration of YGS resulted in a statistically significant improvement in tardive dyskinesia and psychotic symptoms.

CONCLUSIONS

YGS may be an effective and safe therapy to control tardive dyskinesia and psychosis in patients with schizophrenia, that should be further tested in double-blind, placebo-controlled trials.

Yi-gan san for the treatment of borderline personality disorder: an open-label study

BACKGROUND

Numerous medications have been tested on patients with borderline personality disorder (BPD). Although many of these medications have been demonstrated to be useful, no clear main treatment for BPD has emerged. Despite the efficacy of some of the medicines, acceptability and side effects have proven to be barriers to their use. Recent studies indicate that the traditional Chinese herbal medicine yi-gan san (YGS, yokukan-san in Japanese) may be safe and useful in treating behavioral and psychological symptoms in dementia patients. We aimed at evaluating both efficacy and safety of yi-gan san in patients with well-defined BPD.

METHODS

Twenty female outpatients diagnosed with BPD according to DSM-IV criteria and the revised Diagnostic Interview for Borderlines completed a 12-week open-label study with yi-gan san at an average daily dosage of 6.4+/-1.9 g (2.5-7.5 g). Psychometric instruments to assess efficacy included the Brief Psychiatric Rating Scale (BPRS), Hamilton Rating Scales for Depression (HAM-D), Global Assessment of Functioning (GAF), Clinical Global Impression Scale (CGI), and Aggression Questionnaire (AQ).

RESULTS

Most psychometric scale scores exhibited a highly significant improvement (total BPRS; BPRS somatic concern, anxiety, tension, depressive mood, hostility, suspiciousness, motor retardation, uncooperativeness, and excitement subscale; CGI; GAF; AQ) over time.

CONCLUSIONS

In this open-label pilot study, patients treated with YGS showed statistically significant reduction on self-rated and clinician-rated scales. The present findings suggest that yi-gan san might be effective for the treatment of a number of BPD symptoms, including low mood, impulsivity, and aggression.

Anxiolytic effects of the aqueous extract of Uncaria rhynchophylla

The purpose of this study was to characterize the putative anxiolytic-like effects of the aqueous extract of hooks with stem of Uncaria rhynchophylla using the elevated plus maze (EPM) and the hole-board apparatus in rats and mice. Control rats were treated with an equal volume of saline, and positive control rats with buspirone (1 mg/kg). Single or repeated treatments of the aqueous extract of Uncaria rhynchophylla (200 mg/kg/day, p.o.) for 7 days significantly increased the time-spent and entries into open arms of the EPM, and reduced the time-spent and entries into the closed arms versus saline controls (P<0.05). However, no changes in spontaneous locomotor activity or myorelaxant effects were observed versus saline controls. In the hole-board test, repeated treatment with the aqueous extract of Uncaria rhynchophylla (100 or 200 mg/kg/day, p.o.) significantly increased the number of head-dips (P<0.05). In addition, the anxiolytic-like effects of Uncaria rhynchophylla extract as assessed using the EPM test were abolished by WAY 100635 (0.3 mg/kg, i.p.), a 5-HT(1A) receptor antagonist. These results suggest that Uncaria rhynchophylla is an effective anxiolytic agent, and acts via the serotonergic nervous system.

General Strategy for the Syntheses of Corynanthe, Tacaman, and Oxindole Alkaloids

We report herein the total synthesis of the corynanthe alkaloid dihydrocorynantheol and the formal syntheses of the indole alkaloids tacamonine, rhynchophylline, and hirsutine. The strategies for assembling the corynanthe and tacaman skeletal frameworks comprised of both the classical ABD --> ABCD and ABC --> ABCD approaches wherein the variously substituted piperidinone D-rings were formed via ring-closing metathesis (RCM) followed by a 1,4-addition to introduce the requisite side chain at C(15). Since 1,4-additions to alpha,beta-unsaturated lactams represent an underdeveloped field, we conducted a series of studies with two unsaturated lactams employing organocuprates and metal enolates as the nucleophiles. These studies revealed that organocuprates derived from Grignard reagents and either stoichiometric amounts of CuCN or catalytic amounts of CuBr.DMS complex are excellent nucleophiles for such additions; TMSCl was a crucial additive for optimizing these reactions. The anion derived from ethyl 1,3-dithiolane-2-carboxylate was also an excellent nucleophile in these 1,4-additions, although the stereochemistry of such 1,4-additions to carboline-derived, unsaturated lactams was sensitive to substitution on the indole nitrogen atom. The ABD --> ABCD approach to these alkaloids featured a novel one-pot sequence of an RCM reaction and a zirconocene-catalyzed carbomagnesation followed by a second RCM to generate the D-ring.

Insights from molecular investigations of traditional Chinese herbal stroke medicines: implications for neuroprotective epilepsy therapy

Traditional Chinese herbal medicine is the most widely practiced form of herbalism worldwide. It is based on a sophisticated system of medical theory and practice that is distinctly different from orthodox Western scientific medicine. Most traditional therapeutic formulations consist of a combination of several drugs. The combination of multiple drugs is thought to maximize therapeutic efficacy by facilitating synergistic actions and ameliorating or preventing potential adverse effects while at the same time aiming at multiple targets. Orthodox drug therapy has been subject to critical analysis by the "evidence-based medicine" movement, and demands have been made that herbal medicine should be subject to the same kind of scrutiny. However, evaluation of the effectiveness of herbal medicines can be challenging, as their active components are often not known. Accordingly, it may be difficult to ensure that an herbal preparation used in clinical trials contains the components underlying its purported therapeutic effect. We reasoned that the identification of actions of herbal medicines at well-defined molecular targets and subsequent identification of chemical compounds underlying these molecular effects might serve as surrogate markers in the hypothesis-guided evaluation of their therapeutic efficacy. A research program was initiated to characterize in vitro molecular actions of a collection of 58 traditional Chinese drugs that are often used for the treatment of stroke. The results indicate that these drugs possess activity at disparate molecular targets in the signaling pathways involved in N-methyl-d-aspartate (NMDA) receptor-mediated neuronal injury and death. Each herbal drug contains diverse families of chemical compounds, where each family comprises structurally related members that act with low affinity at multiple molecular targets. The data appear to support the multicomponent, multitarget approach of traditional Chinese medicine. Glutamate release and excessive stimulation of NMDA receptors cause status epilepticus-induced neuronal death and are involved in epileptogenesis. Therefore, these results are also relevant to the development of antiepileptogenic and neuroprotective therapy for seizures. The combination of principles of modern molecular medicine with certain ideas of traditional empirical Chinese medicine may be beneficial in translational medicine in general.

Preventive effect of chotosan, a Kampo medicine, on transient ischemia-induced learning deficit is mediated by stimulation of muscarinic M1 but not nicotinic receptor

We have previously shown using a water maze task that transient 2 vessel occlusion (T2VO) induced learning deficit in mice and that the deficit was prevented by pre-treatment of mice with chotosan, a Kampo prescription. In this study, we investigated the mechanism underlying the preventive effect of chotosan on T2VO-induced learning deficit. Chotosan administration 1 h before T2VO operation prevented learning impairment. The extract of Uncaria, a major constituent of chotosan, also had a protective effect on learning impairment in T2VO mice, whereas Uncaria-free chotosan had no beneficial effect on maze performance of T2VO mice. The ameliorative effect of chotosan was blocked by pirenzepine, a muscarinic M1 antagonist, but not by mecamylamine, a nicotinic receptor antagonist. Acetylcholine (ACh) content in the hippocampus of T2VO mice was significantly lower than that in the hippocampus of sham-operated control mice. Chotosan and Uncaria administration attenuated T2VO-induced reduction of ACh levels in the brain. These results suggest that the preventive effect of chotosan on transient ischemia-induced learning impairment is mainly attributable to the effect of Uncaria and that the ameliorative effect is mediated by stimulation of muscarinic M1 receptor.

Uncaria rhynchophylla, a Chinese medicinal herb, has potent antiaggregation effects on Alzheimer's β-amyloid proteins

Because the deposition of beta-amyloid protein (Abeta) is a consistent pathological hallmark of Alzheimer's disease (AD) brains, inhibition of Abeta generation, prevention of Abeta fibril formation, or destabilization of preformed Abeta fibrils would be attractive therapeutic strategies for the treatment of AD. We examined the effects of several medicinal herbs used in traditional Chinese medical formulae on the formation and destabilization of Abeta fibrils by using the thioflavin T binding assay, atomic force microscopic imaging, and electrophoresis. Our study demonstrates that several of these herbs have potent inhibitory effects on fibril formation of both Abeta(1-40) and Abeta(1-42) in concentration-dependent manners; in particular, Uncaria rhynchophylla inhibited Abeta aggregation most intensively. Significant destabilization of preformed Abeta(1-40) and Abeta(1-42) fibrils was also induced by Uncaria rhynchophylla as well as some other herb extracts. Three-dimensional HPLC analysis indicated that the water extract of this herb contains several different chemical compounds, including oxindole and indol alkaloids, which have been regarded as neuroprotective. Our results suggest that Uncaria rhynchophylla has remarkably inhibitory effects on the regulation of Abeta fibrils, and we conclude that this medicinal herb could have the potency to be a novel therapeutic agent to prevent and/or cure AD.

Metabolites of Hirsuteine and Hirsutine, the Major Indole Alkaloids of Uncaria rhynchophylla, in Rats

The metabolic fate of hirsuteine (HT) and hirsutine (HS), the major indole alkaloids of Uncaria rhynchophylla, was investigated using rats. On HPLC analysis, urine from rats orally administered HT were found to contain two metabolites (HT1 and HT2) together with unchanged HT. Similarly HS also was metabolized to two compounds (HS1 and HS2). Metabolite structures were determined to be 11-hydroxyhirsuteine-11-O-beta-D-glucuronide (HT1), 11-hydroxyhirsuteine (HT2), 11-hydroxyhirsutine-11-O-beta-D-glucuronide (HS1) and 11-hydroxyhirsutine (HS2), based on spectroscopic and chemical data. HT1 and HS1 were also detected in bile from rats administered HT and HS, respectively. Total cumulative urinary excretion within 72 h of oral administration was approximately 14% and 26% of the HT and HS doses, respectively, while total cumulative biliary excretion was 35% and 46%, respectively. HT and HS 11-hydroxylation were catalyzed by rat liver microsomes. This 11-hydroxylation activity was inhibited by addition of SKF-525A (a nonselective CYP inhibitor) or cimetidine (a CYP2C inhibitor). These results indicate that orally administered HT and HS are converted to 11-hydroxy metabolites in rats, and that the metabolites are predominantly excreted in bile rather than urine following glucuronidation. Furthermore, the results suggest that CYP2C enzymes are involved, at least in part, in the specific 11-hydroxylation of HT and HS.

Effects of Choto-san and hooks and stems of Uncaria sinensis on antioxidant enzyme activities in the gerbil brain after transient forebrain ischemia

Previously, we revealed that oral administrations of Choto-san, a Kampo formula, and the hooks and stems of Uncaria sinensis Haviland (Rubiaceae), a medicinal plant comprising Choto-san, enhanced superoxide anion and hydroxyl radical scavenging activities in the hippocampus, and prevented delayed neuronal death of pyramidal cells in the hippocampal CA1 region in a transient forebrain ischemia gerbil model. In the present study, for the purpose of clarifying whether the endogenous antioxidant enzymes contribute to these mechanisms, we investigated the effects of Choto-san extract (CSE) and Uncaria sinensis extract (USE) on superoxide dismutase (SOD), catalase (CAT) and glutathione peroxidase (GSH-Px) activities in the brain by using the same experimental model. 1.0% CSE or 3.0% USE were dissolved in water and provided to gerbils ad libitum from 7 days prior to ischemia/reperfusion (i/rp). Seven days of continuous administrations of CSE or USE without i/rp procedure enhanced CAT activity but not SOD and GSH-Px activities in both the hippocampus and cortex. CSE elevated CAT activity in the hippocampus at 7 days and in the cortex at 3h after i/rp. USE raised CAT activity in both the hippocampus and cortex at 3 h and 7 days after i/rp. These results suggest that one of the mechanisms of the protective effects of CSE and USE against transient brain ischemia-induced neuronal damage may be their enhancing effect on CAT activity in the brain.

Protective effect of rhynchophylline and isorhynchophylline on in vitro ischemia-induced neuronal damage in the hippocampus: putative neurotransmitter receptors involved in their action

Rhynchophylline and isorhynchophylline are major tetracyclic oxindole alkaloid components of Uncaira species, which have been long used as medicinal plants. In this study we examined the protective effects of rhynchophylline and isorhynchophylline on in vitro ischemia-induced neuronal damage in the hippocampus and interaction of these alkaloids with neurotransmitter receptors in a receptor expression model of Xenopus oocytes. In vitro ischemia was induced by exposing the hippocampal slices to oxygen- and D-glucose-deprived medium over 8 min. The resultant neuronal damage was elucidated as deterioration of population spike (PS) amplitudes evoked trans-synaptically by electrical stimulation of Schaffer collaterals and recorded in the CA1 area. Rhynchophylline and isorhynchophylline, as well as the N-methyl-D-aspartate (NMDA) antagonist (+/-)-2-amino-5-phosphono-valeric acid (APV), the muscarinic M1 receptor antagonist pirenzepine, and the 5-HT2 receptor antagonist ketanserin, attenuated the in vitro ischemia-induced neuronal damage in a concentration-dependent manner. There was no difference in the extent of protection against the neuronal damage between rhynchophylline and isorhynchophylline treatment. In Xenopus oocytes expressing the rat brain receptors encoded by total RNA, both rhynchophylline and isorhynchophylline reduced muscarinic receptor- and 5-HT2 receptor-mediated current responses in a competitive manner. Together with our previous findings that rhynchophylline and isorhynchophylline have a non-competitive antagonistic effect on the NMDA-type ionotropic glutamate receptors, the present results suggest that these alkaloids exert their protective action against ischemia-induced neuronal damage by preventing NMDA, muscarinic M1, and 5-HT2 receptors-mediated neurotoxicity during ischemia.

Cytoprotective effect on oxidative stress and inhibitory effect on cellular aging of Uncaria sinensis Havil

The ethanol extract from the hooks and stems of Uncaria sinensis Havil (Rubiaceae) exhibited significant inhibitory activity on oxidative stress and the age-dependent shortening of the telomeric DNA length. In the peroxidation model using t-BuOOH, the Uncaria sinensis extract showed a notable cytoprotective effect on the HEK-N/F cells with 65.0 +/- 3.0% of cell viability when compared with control cells at a concentration of 50 microg/ml. In addition, the Uncaria sinensis extract exhibited a significant cytoprotective effect against UVB-induced oxidative damage. The life-span of the HEK-N/F cells was elongated by 201% as a result of the continuous administration of 3 microg/ml of the Uncaria sinensis extract compared to that of the control. These observations were attributed to the inhibitory effect of the Uncaria sinensis extract on the age-dependent shortening of the telomere length as shown by the Southern blots of the terminal restriction fragments (TRFs) of DNA extracted from subculture passages.

Protective effects of Choto-san and hooks and stems of Uncaria sinensis against delayed neuronal death after transient forebrain ischemia in gerbil

Previously, we revealed that Choto-san (Diao-teng-san in Chinese), a Kampo formula, is effective on vascular dementia clinically, and the hooks and stems of Uncaria sinensis (Oliv.) Havil., a medicinal plant comprising Chotosan, has a neuroprotective effect in vitro. In the present study, for the purpose of clarifying their effects in vivo, we investigated whether the oral administration of Choto-san extract (CSE) or U. sinensis extract (USE) reduces delayed neuronal death following ischemia/reperfusion (i/rp) in gerbils. Transient forebrain ischemia was induced by bilateral carotid artery occlusion for 4 min, and two doses (1.0% and 3.0%) of CSE or USE were dissolved in drinking water and provided to the gerbils ad libitum from 7 days prior to i/rp until 7 days after i/rp. It was found that 1.0% and 3.0% CSE treatments significantly reduced pyramidal cell death in the hippocampal CA1 region at 7 days post i/rp. Three percent USE treatment also inhibited pyramidal cell death significantly at 7 days after i/rp. Superoxide anion and hydroxyl radical scavenging activities of the homogenized hippocampus at 7 days after i/rp in the 1.0% CSE- and 3.0% USE-treated groups were significantly enhanced compared to those of control. Further, lipid peroxide and NO2-/NO3- levels of the homogenized hippocampus at 48h after i/rp in the 1.0% CSE- and 3.0% USE-treated groups were significantly lower than those of control. These results suggest that the oral administration of CSE or USE provides a protective effect against transient ischemia-induced delayed neuronal death by reducing oxidative damage to neurons.

Effects of Methanol Extract of Uncariae Ramulus et Uncus on Ibotenic Acid-Induced Amnesia in the Rat

In the present study, we investigated the effects of Uncariae Ramulus et Uncus (UR) on learning and memory in the Morris water maze task and the central cholinergic system of rats with excitotoxic medial septum (MS) lesion. In the water maze test, the animals were trained to find a platform in a fixed position during 6 days and then received a 60-s probe trial in which the platform was removed from the pool on the 7th day. Ibotenic lesion of the MS showed impaired performance of the maze test and severe cell losses in the septohippocampal cholinergic system (SHC), as indicated by decreased choline acetyltransferase-immunoreactivity and acetylcholinesterase-reactivity in the hippocampus. Daily administrations of UR (100 mg/kg, i.p.) for 21 consecutive days produced significant reversals of ibotenic acid-induced deficit in learning and memory. These treatments also reduced the loss of cholinergic immunoreactivity in the hippocampus induced by ibotenic acid. These results demonstrated that impairments of spatial learning and memory may be attributable to degeneration of SHC neurons and that UR ameliorated learning and memory deficits partly through neuroprotective effects on the central acetylcholine system. Our studies suggest that UR may be useful in the treatment of Alzheimer's disease.

Methanol Extracts of Hamelia patens Containing Oxindole Alkaloids Relax KCl-Induced Contraction in Rat Myometrium

Hamelia patens JAQC. (Rubiaceae) is a medicinal bush widely distributed in tropical areas of the American continent. It is used in Mexican Traditional Medicine for the treatment of menstrual disorders, therefore suggesting that its chemical constituents may have some effect on myometrium contractility. Physiological effects might differ due to quantitative variations in the content of alkaloids arising from its wide geographical distribution. To test this hypothesis, the content of oxindole alkaloids in methanol extracts of five different samples collected in Mexico was quantified by GC-MS. Each extract was assayed on contractility of estrogen-primed rat myometrium. Variations in the content of alkaloids were observed among the different samples. All samples relaxed in a concentration-dependent manner the high KCl-induced contraction in rat myometrium. Those which lack rumberine and/or maruquine displayed a higher relaxant effect than samples containing them, suggesting that these alkaloids might counteract the effects of isopteropodine. However, in contrast with verapamil, Hamelia patens metanol extracts are poor relaxants.

In vitro vasodilator mechanisms of the indole alkaloids rhynchophylline and isorhynchophylline, isolated from the hook of Uncaria rhynchophylla (Miquel)

Rhynchophylline (Rhy) and isorhynchophylline (Isorhy), indole alkaloids from Uncaria hooks, reportedly exert hypotensive and vasodilatory effects, but the mechanism of action is unclear. We therefore investigated the relaxant effects of these two isomeric alkaloids in rat arteries in vitro, in particular in respect of the various functional Ca2+ pathways. Both Rhy and Isorhy relaxed aortic rings precontracted with phenylephrine (PE, 1 microM) in a dose-dependent manner (3-300 microM). Removal of endothelium and preincubation with L-NAME (300 microM) slightly inhibited but did not prevent the relaxant response. These results indicate that Rhy and Isorhy act largely in an endothelium-independent manner. Unlike nicardipine, both alkaloids not only inhibited the contraction induced by 60 mM KCl (IC50 20-30 microM), but also that induced by PE and U46619, albeit to a lesser extent (IC50 100 and 200 microM, respectively). These results suggest that Rhy and Isorhy may act via multiple Ca2+ pathways. In contrast to their inhibitory effects on KCl-induced and receptor-mediated contractions, where both isomers were comparably potent, Rhy was more potent than Isorhy at higher concentrations (>100 microM) in inhibiting both caffeine (25 mM)- and cyclopiazonic acid (CPA, 30 microM)-induced contractions. Similar results observed with caffeine in Ca2+-containing medium were also observed in Ca2+-free medium. However, 0.1-0.3 microM nicardipine (which completely inhibited KCl-induced contraction) had no significant inhibitory effect on CPA-induced contractions. Taken together, these results indicate discrimination between these two isomers with respect to Ca2+-induced Ca2+ release and non-L-type Ca2+ channel, but not for IP3-induced Ca2+ release and L-type Ca2+ channels. Similar relaxant responses to KCl- and caffeine-induced contractions were seen when these two alkaloids were tested on the smaller mesenteric and renal arteries. In conclusion, the vasodilatory effects of Rhy and Isorhy are largely endothelium independent and are mediated by L-type Ca2+ channels. At higher concentrations, they also affect other Ca2+-handling pathways, although to a lesser extent. While there is no discrimination between the two isomers with respect to the contraction induced by KCl or agonists (PE and U46619), differential effects between Rhy and Isorhy were seen on caffeine- and CPA-induced contractions.

Protective effects of methanol extract of Acori graminei rhizoma and Uncariae Ramulus et Uncus on ischemia-induced neuronal death and cognitive impairments in the rat

Acori graminei rhizoma (AGR) and Uncariae Ramulus et Uncus (URE) have been widely used as herbal medicine against ischemia. In order to investigate whether AGR and URE influenced cerebral ischemia-induced neuronal and cognitive impairments, we examined the effect of AGR and URE on ischemia-induced cell death in the striatum, cortex and hippocampus, and on the impaired learning and memory in the Morris water maze and radial eight-arm maze in rats. After middle cerebral artery occlusion (MCAO) for 2 h, rats were administered saline, AGR or URE (100 mg/kg, p.o.) daily for three weeks, followed by their training to the tasks. In the water maze test, the animals were trained to find a platform in a fixed position during 6 days and then received a 60-s probe trial in which the platform was removed from the pool on the 7th day. In the radial eight-arm maze, animals were tested six times per week for 1 week. Rats with ischemic insults showed impaired learning and memory on the tasks. Pretreatment with AGR and URE produced a significant improvement in escape latency to find the platform in the Morris water maze and in the number of choice errors in the radial arm maze test. Consistent with behavioral data, pretreatments with AGR and URE significantly reduced ischemia-induced cell death in the hippocampal CA1 area. These results demonstrated that AGR and URE have a protective effect against ischemia-induced neuronal loss and learning and memory damage. Our studies suggest that AGR and URE may be useful in the treatment of vascular dementia.

Choto-san prevents occurrence of stroke and prolongs life span in stroke-prone spontaneously hypertensive rats

The effects of long-term oral administration of choto-san (diao-teng-san in Chinese) extract on the occurrence of stroke and life span were investigated in stroke-prone spontaneously hypertensive rats (SHR-SPs). Twenty-four rats were ramdomized into three groups. From 8 weeks of age, 0.1% and 0.3% choto-san groups were given water containing 0.1% (150 mg/kg/day) and 0.3% (450 mg/kg/day) choto-san extract, respectively. A control group was given only water. The mean survival times of the control group, 0.1% and 0.3% choto-san groups were 122.1, 159.8 and 176.8 days, respectively. The percent survivals of both the 0.1% and 0.3% choto-san groups were significantly enhanced compared to the control (Kaplan-Meier analysis followed by log-rank test; 0.1% choto-san: p < 0.05; 0.3% choto-san: p < 0.05). Furthermore, the cumulative percent occurrence of neurological and behavioral signs accompying stroke in the 0.3% choto-san group was significantly inhibited compared to the control (p < 0.05). These results suggested that choto-san prevents the occurrence of stroke and prolongs the life span of SHR-SPs.

Alkaloid fraction of Uncaria rhynchophylla protects against N-methyl-D-aspartate-induced apoptosis in rat hippocampal slices

Uncaria rhynchophylla is a medicinal herb which has sedative and anticonvulsive effects and has been applied in the treatment of epilepsy in Oriental medicine. In this study, the effect of alkaloid fraction of U. rhynchophylla against N-methyl-D-aspartate (NMDA)-induced neuronal cell death was investigated. Pretreatment with an alkaloid fraction of U. rhynchophylla for 1 h decreased the degree of neuronal damage induced by NMDA exposure in cultured hippocampal slices and also inhibited NMDA-induced enhanced expressions of apoptosis-related genes such as c-jun, p53, and bax. In the present study, the alkaloid fraction of U. rhynchophylla was shown to have a protective property against NMDA-induced cytotoxicity by suppressing the NMDA-induced apoptosis in rat hippocampal slices.

Pharmacological evidence for antidementia effect of Choto-san (Gouteng-san), a traditional Kampo medicine

To clarify the clinical efficacy of one of the traditional medicines in the treatment of patients with vascular dementia, we investigated the pharmacological activities of Choto-san in animal models. Pretreatment with Choto-san (0.75-6.0 g/kg po), a component herb, Chotoko (75-600 mg/kg po), and indole alkaloids and phenolic fractions of Chotoko prevented ischemia-induced impairment of spatial learning behaviour in water maze performance of mice. A single administration of Choto-san (0.5 to 6.0 g/kg po) or Chotoko (Uncaria genus) produced a dose-dependent antihypertensive effect in spontaneously hypertensive rats (SHR) and partly inhibited the induction of the apoplexy in stroke-prone SHR (SHR-SP). Choto-san, Chotoko, and its phenolic constituents, (-)epicatechin and caffeic acid, significantly protected NG108-15 cells from injury induced by H(2)O(2) exposure in vitro and also inhibited lipid peroxidation in the brain homogenate. Indole alkaloids, rhynchophylline and isorhynchophylline (1-100 microM), reversibly reduced N-methyl-D-aspartate (NMDA)-induced current concentration dependently in NMDA receptor-expressed Xenopus oocytes. These results suggest that antidementia effects of Choto-san are due to antihypertensive, free radical scavenging and antiexcitotoxic effects, which are attributed at least partly to phenolic compounds and indole alkaloids contained in Chotoko.

Rhynchophylline and isorhynchophylline inhibit NMDA receptors expressed in Xenopus oocytes

Rhynchophylline and isorhynchophylline are major tetracyclic oxindole alkaloid components of Uncaira species, which have been long used as medicinal plants. In this study, the effects of rhynchophylline and isorhynchophylline on the ionotropic and metabotropic glutamate receptor-mediated current responses were examined using Xenopus oocytes injected with total RNA prepared from rat cortices or cerebelli. Rhynchophylline and isorhynchophylline (1-100 microM) per se failed to induce membrane current, but these alkaloids reversibly reduced N-methyl-D-aspartate (NMDA)-induced current in a concentration-dependent but voltage-independent manner. The IC(50) values of rhynchophylline and isorhynchophylline were 43.2 and 48.3 microM, respectively. Substitution of Ba(2+) for Ca(2+) in the recording medium did not alter the extent of rhynchophylline- and isorhynchophylline-induced suppression of NMDA currents. In contrast, neither alkaloid had an effect on the currents mediated by ionotropic kainic acid-type and (+/-)-alpha-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid (AMPA)-type glutamate receptors or by the metabotropic glutamate receptor(1 and 5) (mGlu(1/5)). Rhynchophylline and isorhynchophylline (30 microM) significantly reduced the maximal current responses evoked by NMDA and glycine (a co-agonist of NMDA receptor), but had no effect on the EC(50) values and Hill coefficients of NMDA and glycine for inducing currents. These alkaloids showed no interaction with the polyamine binding site, the Zn(2+) site, proton site or redox modulatory site on the NMDA receptor. These results suggest that rhynchophylline and isorhynchophylline act as noncompetitive antagonists of the NMDA receptor and that this property may contribute to the neuroprotective and anticonvulsant activity of the Uncaira species plant extracts.

Neuroprotection by methanol extract of Uncaria rhynchophylla against global cerebral ischemia in rats

In traditional Oriental medicine, Uncaria rhynchophylla has been used to lower blood pressure and to relieve various neurological symptoms. However, scientific evidence related to its effectiveness or precise modes of action has not been available. Thus, in the current study, we evaluated neuroprotective effects of U. rhynchophylla after transient global ischemia using 4-vessel occlusion model in rats. Methanol extract of U. rhynchophylla administered intraperitoneally (100-1000 mg/kg at 0 and 90 min after reperfusion) significantly protected hippocampal CA1 neurons against 10 min transient forebrain ischemia. Measurement of neuronal cell density in CA1 region at 7 days after ischemia by Nissl staining revealed more than 70% protection in U. rhynchophylla-treated rats compared to saline-treated animals. In U. rhynchophylla-treated animals, induction of cyclooxygenase-2 in hippocampus at 24 hr after ischemia was significantly inhibited at both mRNA and protein levels. Furthermore, U. rhynchophylla extract inhibited TNF-alpha and nitric oxide production in BV-2 mouse microglial cells in vitro. These anti-inflammatory actions of U. rhynchophylla extract may contribute to its neuroprotective effects.

Protective effect of phenolic compounds isolated from the hooks and stems of Uncaria sinensis on glutamate-induced neuronal death

We isolated the phenolic compounds epicatechin, catechin, procyanidin B-1, procyanidin B-2, hyperin and caffeic acid from the hooks and stems of Uncaria sinensis (HSUS), and studied their protective effects against glutamate-induced neuronal death in cultured rat cerebellar granule cells. Cell viability evaluated by MTT assay was significantly increased by application of epicatechin (100-300 microM), catechin (300 microM), procyanidin B-1 (30-300 microM) and procyanidin B-2 (100-300 microM) compared with exposure to glutamate only. 45Ca2+ influx into cells induced by glutamate was also significantly inhibited by administration ofepicatechin (300 microM), catechin (300 microM), procyanidin B-1 (100-300 microM) and procyanidin B-2 (100-300 microM). These results suggest that epicatechin, catechin, procyanidin B-1 and procyanidin B-2 are the active components of HSUS that protect against glutamate-induced neuronal death in cultured cerebellar granule cells by inhibition of Ca2+ influx.