ESP-102, a standardized combined extract of Angelica gigas, Saururus chinensis and Schizandra chinensis, significantly improved scopolamine-induced memory impairment in mice

Angelica gigas: Signature Compounds, In Vivo Anticancer, Analgesic, Neuroprotective and Other Activities, and the Clinical Translation Challenges

Angelica gigas Nakai (AGN) root is a medicinal herbal widely used in traditional medicine in Korea. AGN root ethanolic extract dietary supplements are marketed in the United States for memory health and pain management. We comprehensively reviewed the anticancer, analgesic, pro-memory and other bio-activities of AGN extract and its signature phytochemicals decursin, decursinol angelate, and decursinol a decade ago in 2012 and updated their anticancer activities in 2015. In the last decade, significant progress has been made for understanding the pharmacokinetics (PK) and metabolism of these compounds in animal models and single dose human PK studies have been published by us and others. In addition to increased knowledge of the known bioactivities, new bioactivities with potential novel health benefits have been reported in animal models of cerebral ischemia/stroke, anxiety, sleep disorder, epilepsy, inflammatory bowel disease, sepsis, metabolic disorders, osteoporosis, osteoarthritis, and even male infertility. Herein, we will update PK and metabolism of pyranocoumarins, review in vivo bioactivities from animal models and human studies, and critically appraise the relevant active compounds, the cellular and molecular pharmacodynamic targets, and pertinent mechanisms of action. Knowledge gaps include whether human pyranocoumarin PK metrics are AGN dose dependent and subjected to metabolic ceiling, or metabolic adaptation after repeated use. Critical clinical translation challenges include sourcing of AGN extracts, product consistency and quality control, and AGN dose optimization for different health conditions and disease indications. Future research directions are articulated to fill knowledge gaps and address these challenges.

Synergistic Neuroprotective Effects of Mature Silkworm and Angelica gigas Against Scopolamine-Induced Mild Cognitive Impairment in Mice and H2O2-Induced Cell Death in HT22 Mouse Hippocampal Neuronal Cells

We previously reported that mature Bombyx mori silkworm (SW) ameliorated scopolamine (Sco)-induced amnesia, and Angelica gigas (AG) prevented cognitive impairment. SW is known for its gastroprotective effects such as improving liver function and alleviating the effects of Parkinson's disease. AG is known for its neuroprotective effects and for lowering the effects of low-density lipoprotein cholesterol. However, the neuroprotective effect of combined SW and AG (SWA-1) treatment and the underlying molecular mechanism by which SWA-1 regulates neurodegenerative diseases remains unclear. We evaluated the neuroprotective effect of SWA-1 against Sco-induced mild cognitive impairment in mice and H₂O₂-induced cell death in HT22 mouse hippocampal neuronal cells and elucidated the underlying molecular mechanism. Morris water maze and Y-maze tests were performed to examine the learning and memory abilities of mice. The underlying molecular mechanism was investigated by using western blotting. We demonstrated that SWA-1 significantly protects against H₂O₂-induced cell death in HT22 mouse hippocampal neuronal cells. SWA-1 also significantly reversed Sco-induced spatial learning and memory impairment. Specifically, SWA-1 upregulates the protein levels of phosphorylated extracellular signal-related kinase (Erk1/2) and phosphorylated p38 MAP kinase (p38). SWA-1 remarkably decreased the apoptotic index Bax/Bcl2 expression in the hippocampus of Sco-treated mice. Our results suggest that SWA-1 may be administered as alternative therapy for cognitive impairment and neurodegenerative diseases and should be studied further in human trials.

Bioactive Compounds and Traditional Herbal Medicine: Promising Approaches for the Treatment of Dementia

Dementia is a term that encompasses a group of clinical symptoms affecting memory, thinking and social abilities, characterized by progressive impairment of memory performance and cognitive functions. There are several factors involved in the pathogenesis and progression of dementia, such as old age, brain ischemia, toxin exposure, and oxidative stress. There are extensive similarities between dementia and Alzheimer's disease (AD) either in clinical manifestations or experimental animal models. AD is the most dominant form of dementia, characterized by the accumulation of beta-amyloid protein and cholinergic neurotransmission deficits in the brain. Currently available medications for the treatment of dementia, such as choline esterase inhibitors, N-methyl-D-aspartate (NMDA) antagonists (memantine), have short-term efficacy and only relieve symptoms rather than targeting the main underlying pathogenesis. Several animal studies and clinical trials are being conducted to provide a rational approach to these medicinal plants in the prevention or treatment of memory deficits. This review highlights the potential effects of medicinal plants and their derived lead molecules, and explains the related mechanisms and effects reviewed from published literature as major thrust aspects and hopeful strategies in the prevention or treatment of dementia.

Chinese Herbal Medicine Interventions in Neurological Disorder Therapeutics by Regulating Glutamate Signaling

Glutamate is the major excitatory neurotransmitter in the central nervous system, and its signaling is critical for excitatory synaptic transmission. The well-established glutamate system involves glutamate synthesis, presynaptic glutamate release, glutamate actions on the ionotropic glutamate receptors (NMDA, AMPA, and kainate receptors) and metabotropic glutamate receptors, and glutamate uptake by glutamate transporters. When the glutamate system becomes dysfunctional, it contributes to the pathogenesis of neurodegenerative and neuropsychiatric diseases such as Alzheimer's disease, Parkinson's disease, depression, epilepsy, and ischemic stroke. In this review, based on regulating glutamate signaling, we summarize the effects and underlying mechanisms of natural constituents from Chinese herbal medicines on neurological disorders. Natural constituents from Chinese herbal medicine can prevent the glutamate-mediated excitotoxicity via suppressing presynaptic glutamate release, decreasing ionotropic and metabotropic glutamate receptors expression in the excitatory synapse, and promoting astroglial glutamate transporter expression to increase glutamate clearance from the synaptic cleft. However, some natural constituents from Chinese herbal medicine have the ability to restore the collapse of excitatory synapses by promoting presynaptic glutamate release and increasing ionotropic and metabotropic glutamate receptors expression. These regulatory processes involve various signaling pathways, which lead to different mechanistic routes of protection against neurological disorders. Hence, our review addresses the underlying mechanisms of natural constituents from Chinese herbal medicines that regulate glutamate systems and serve as promising agents for the treatment of the above-mentioned neurological disorders.

Schisandrin A and B enhance the dentate gyrus neurogenesis in mouse hippocampus

Schisandrin A and B (Sch A and B) are the main effective components of Schisandra chinensis (S. chinensis), which is traditionally used to enhance mental and intellectual functions in eastern Asia. Previously, we reported Sch A and B remarkably affect adult neurogenesis in the subventricular zone of mouse lateral ventricle. Since the neurogenesis in the hippocampal dentate gyrus (DG) is more important to learning, memory and cognition, here we further examined their effects on the adult DG neurogenesis. Phosphohistone H3 (PHH3) immunostaining showed that Sch B significantly enhanced the cell proliferation in the DG. Glial fibrillary acidic protein (GFAP, mostly labels astrocytes and some stem cells) staining was used to further identify the proliferating cell type. Dramatically, increases of GFAP⁺ cells in both Sch A and B treated groups were observed. What's more, the total numbers of the mature neurons labeled by neuron-specific nuclear protein (NeuN) were also increased in both Sch A and B treated groups compared with the controls. Together, Sch A and B enhance the adult DG neurogenesis by increasing astrocytes/stem cells and improving the survival and maturation of DG neurons. Our study shed a new light on the neuropharmacological functions of the herbal medicine S. chinensis.

In Vivo Pharmacological Comparison of TAK-071, a Positive Allosteric Modulator of Muscarinic M1 Receptor, and Xanomeline, an Agonist of Muscarinic M1/M4 Receptor, in Rodents

Activation of the M₁ muscarinic acetylcholine receptor (M₁R) may be an effective therapeutic approach for Alzheimer's disease (AD), dementia with Lewy bodies, and schizophrenia. Previously, the M₁R/M₄R agonist xanomeline was shown to improve cognitive function and exert antipsychotic effects in patients with AD and schizophrenia. However, its clinical development was discontinued because of its cholinomimetic side effects. We compared in vivo pharmacological profiles of a novel M₁R-selective positive allosteric modulator, TAK-071, and xanomeline in rodents. Xanomeline suppressed both methamphetamine- and MK-801-induced hyperlocomotion in mice, whereas TAK-071 suppressed only MK-801-induced hyperlocomotion. In a previous study, we showed that TAK-071 improved scopolamine-induced cognitive deficits in a rat novel object recognition task (NORT) with 33-fold margins versus cholinergic side effects (diarrhea). Xanomeline also improved scopolamine-induced cognitive impairments in a NORT; however, it had no margin versus cholinergic side effects (e.g., diarrhea, salivation, and hypoactivity) in rats. These side effects were observed even in M₁R knockout mice. Evaluation of c-Fos expression as a marker of neural activation revealed that xanomeline increased the number of c-Fos-positive cells in several cortical areas, the hippocampal formation, amygdala, and nucleus accumbens. Other than in the orbital cortex and claustrum, TAK-071 induced similar c-Fos expression patterns. When donepezil was co-administered to increase the levels of acetylcholine, the number of TAK-071-induced c-Fos-positive cells in these brain regions was increased. TAK-071, through induction of similar neural activation as that seen with xanomeline, may produce procognitive and antipsychotic effects with improved cholinergic side effects.

Pharmacodynamic and urinary metabolomics studies on the mechanism of Schisandra polysaccharide in the treatment of Alzheimer's disease

This study was designed to investigate the antagonism of SCP in Aβ25–35-induced AD rats by intervening in neurotransmitters and metabolites.

Effect of Salacia reticulata W. and Clitoria ternatea L. on the cognitive and behavioral changes in the streptozotocin-induced young diabetic rats

BACKGROUND

Diabetes mellitus (DM) of juvenile onset affects both the peripheral and central nervous systems (CNS). However, central effects are less documented and studied than peripheral deficits. Currently, the only feasible treatment available for type 1 DM (T1DM) is insulin which has its own limitations. Hence, an alternative therapy, especially a newer herbal formulation is very much the need of the time. The present study aimed to determine the effects of the alcoholic extracts of roots of the Salacia reticulata W. (SR) and Clitoria ternatea L. (CT) on cognitive and behavioral changes in juvenile diabetic rats.

METHODS

Diabetes was induced in 25-day-old Wistar rats by streptozotocin (50 mg/kg bw, IP). Animals were divided into seven groups (n=6). Rats were treated with root extracts of SR and CT (100 mg/kg BW each) for 30 days, from day 1 and day 20 of diabetes confirmation. Then, rats were tested in elevated plus maze (EPM) and Morris water maze (MWM).

RESULTS

A statistically significant (p<0.05) difference was observed between the SRCT group and diabetic groups of rats. Apart from decreasing FBS, the combined therapy also proved beneficial as nootropic agent in rats with early-onset diabetes. However, significant improvement is observed only in the learning and memory among preventive group, but not in the curative group.

CONCLUSIONS

SRCT, a herbal formula, when used in combination, has a more potent effect in preventing the deleterious effects of juvenile diabetes on cognitive and behavioral changes.

Neuroprotective and Cognitive Enhancement Potentials of Angelica gigas Nakai Root: A Review

Angelica gigas Nakai is an important medicinal plant with health promoting properties that is used to treat many disorders. In traditional herbal medicine, the root of this plant is used to promote blood flow, to treat anemia, and is used as sedative or tonic agent. The root contains various bioactive metabolites; in particular, decursin and decursinol (pyranocoumarin type components) have been reported to possess various pharmacological properties. Recently, several in vitro and in vivo studies have reported that the crude extracts and isolated components from the root of A. gigas exhibited neuroprotective and cognitive enhancement effects. Neuronal damage or death is the most important factor for many neurodegenerative diseases. In addition, recent studies have clearly demonstrated the possible mechanisms behind the neuroprotective action of extracts/compounds from the root of A. gigas. In the present review, we summarized the neuroprotective and cognitive enhancement effects of extracts and individual compounds from A. gigas root.

ESP-102, a Combined Herbal Extract of Angelica gigas, Saururus chinensis, and Schisandra chinensis, Changes Synaptic Plasticity and Attenuates Scopolamine-Induced Memory Impairment in Rat Hippocampus Tissue

ESP-102, an extract from Angelica gigas, Saururus chinensis, and Schisandra chinensis, has been used as herbal medicine and dietary supplement in Korea. Despite the numerous bioactivities in vitro and in vivo studies, its effects on neuronal networks remain elusive. To address the neuronal effect, we examined synaptic plasticity in organotypic hippocampal slice culture with multielectrode array. Our results showed an increase in excitatory postsynaptic potential (EPSP), indicating the induction of long-term potentiation (LTP), in the presence of ESP-102. In addition, the neuroprotective effect of ESP-102 was also tested by application of scopolamine to the hippocampal slice. Interestingly, ESP-102 competitively antagonized the preventative LTP effect induced by scopolamine. The scopolamine-induced reduction in brain-derived neurotrophic factor (BDNF) and GluR-2 expression was also rescued by ESP-102. In terms of mode of action, ESP-102 appears to act on the presynaptic region independent of AMPA/NMDA receptors. Based on these findings, ESP-102 can be suggested as a novel herbal ingredient with memory enhancing as well as neuroprotective effects.

Angelica sinensis reduced Aβ-induced memory impairment in rats

BACKGROUND

Studies have shown that Angelica sinensis (JiLin AoDong Medicine Industry Groups Co., Ltd., Jilin, China) root (AS) ameliorates various diseases, although its effects in Alzheimer's disease (AD) have not been elucidated.

PURPOSE

The present study examined the effects of AS in a rat model of AD.

METHODS

Positional Aβ injections were administered to rats. The behavioral effects of AS administration were examined using the Morris water maze, and the molecular effects on gene and protein expression, and apoptosis, were determined.

RESULTS

AS reversed the social behavioral impairments observed in this rat model of Aβ-induced memory impairment. Western blot analysis also revealed lower hippocampal levels of Aβ and β-site amyloid precursor protein-cleaving enzyme. Terminal deoxynucleotidyl transferased UTP nick end labeling indicated that AS significantly inhibited apoptosis via effects on nuclear factor kappa B (NF-κB) signaling. Real-time PCR, enzyme-linked immunosorbent assay, and immunohistochemical staining indicated that AS effectively inhibited inflammation and upregulated expression of glial cell line-derived neurotrophic factor (GDNF) and brain-derived neurotrophic factor (BDNF) in the hippocampus of this rat AD model.

DISCUSSION

AS effectively rescued the symptoms of AD in a rat model by inhibiting inflammation, apoptosis, and NF-κB signaling pathway.

CONCLUSION

These findings suggested that AS could provide a potential drug for the treatment of AD.

Effect of nigranoic acid on Ca²⁺ influx and its downstream signal mechanism in NGF-differentiated PC12 cells

ETHNOPHARMACOLOGICAL RELEVANCE

Schisandra chinensis has a long history of use as a famous traditional Chinese medicine. The plants of genus Schisandra, especially Schisandra neglecta, Schisandra rubriflora, and Schisandra sphaerandra are used in the same way as Schisandra chinensis in the folk medicine to treat insomnia, fatigue, increasing intelligence, and tranquilizing. Many studies showed that lignans were the major active components of Schisandra genus, whereas the bioactivity of abundant triterpenoids in Schisandra genus, such as nigranoic acid (SBB1, 3,4-secocycloartene triterpenoid), has not been examined yet in neuropathology.

MATERIALS AND METHODS

After treating with SBB1, intracellular Ca(2+) concentration was analyzed by Ca(2+) fluorescent indicator (Fluo-4 AM) in NGF-differentiated PC12 cells. Intracellular nitric oxide (NO) level was analyzed using NO fluorescent indicator (DAF-FM). The expression of extracellular signal regulated kinase 1 and 2 (ERK1/2) was analyzed by western blotting, and the temporal mRNA for BDNF and c-fos was analyzed using reverse transcription quantitative PCR.

RESULT

We found that SBB1 induced Ca(2+) influx in a time- and concentration-dependent manner, which was significantly attenuated in Ca(2+) free media. SBB1 promoted the intracellular NO production which depended on increasing cytoplasmic Ca(2+) level. Moreover, SBB1 stimulated activation of ERK1/2 through Ca(2+)-CaMKII pathway. In addition, we found that SBB1 increased the expression of BDNF and c-fos mRNA.

CONCLUSION

These results suggest that SBB1 is able to promote NO production and stimulate phosphorylation of ERK1/2 through Ca(2+) influx, further impact expression of BDNF and c-fos, which provides evidence for the effects of SBB1 that may be benefit to enhance mental and intellectual functions.

Schisantherin A recovers Aβ-induced neurodegeneration with cognitive decline in mice

Schisantherin A (STA) is a main bioactive lignan isolated from Schisandra chinensis (Turcz.) Baill., which has been widely used as a tonic in traditional Chinese medicine for many years. Lots of studies have reported that STA exhibited anti-inflammatory and antioxidant effects. This paper was designed to investigate the effects of STA on cognitive function and neurodegeneration in the mouse control of Alzheimer's disease (AD) induced by Aβ1-42. It was found that successive intracerebroventricular (ICV) administration of STA (0.01 and 0.1mg/kg) for 5days significantly attenuated Aβ1-42-induced learning and memory impairment as measured by the Y-maze test, shuttle-box test and Morris water maze test. Furthermore, STA at a dose of 0.1mg/kg restored the activities of superoxide dismutase (SOD) and glutathione peroxidase (GSH-Px) as well as the levels of Aβ1-42, malondialdehyde (MDA) and glutathione (GSH) to some extent in the hippocampus and cerebral cortex. It also noticeably improved the histopathological changes in the hippocampus. The results suggested that STA might protect against cognitive deficits, oxidative stress and neurodegeneration induced by Aβ1-42, and serve as a potential agent in treatment of AD.

Traditional Korean East Asian medicines and herbal formulations for cognitive impairment

Hanbang, the Traditional Korean Medicine (TKM), is an inseparable component of Korean culture both within the country, and further afield. Korean traditional herbs have been used medicinally to treat sickness and injury for thousands of years. Oriental medicine reflects our ancestor’s wisdom and experience, and as the elderly population in Korea is rapidly increasing, so is the importance of their health problems. The proportion of the population who are over 65 years of age is expected to increase to 24.3% by 2031. Cognitive impairment is common with increasing age, and efforts are made to retain and restore the cognition ability of the elderly. Herbal materials have been considered for this purpose because of their low adverse effects and their cognitive-enhancing or anti-dementia activities. Herbal materials are reported to contain several active compounds that have effects on cognitive function. Here, we enumerate evidence linking TKMs which have shown benefits in memory improvements. Moreover, we have also listed Korean herbal formulations which have been the subject of scientific reports relating to memory improvement.

The memory ameliorating effects of INM-176, an ethanolic extract of Angelica gigas, against scopolamine- or Aβ(1-42)-induced cognitive dysfunction in mice

ETHNOPHARMACOLOGICAL RELEVANCE

Alzheimer's disease is a neurodegenerative disorder associated with cognitive impairment and cholinergic neuronal death. INM-176 is a standardized ethanolic extract of Angelica gigas Nakai that has been traditionally used in herbal medicine in China, Japan, and Korea to treat anemia or as a sedative. We investigated whether INM-176 exhibits anti-amnesic effects.

MATERIALS AND METHODS

Memory impairment was induced by scopolamine, a cholinergic muscarinic receptor antagonist, or amyloid β(1-42) (Aβ(1-42)) protein. Anti-amnesic effects of INM-176 were measured by the passive avoidance and the Morris water maze tasks in mice. We also examined the effect of INM-176 on the acetylcholinesterase activity, as well as Aβ(1-42) protein-induced astrogliosis or cholinergic neuronal loss in the brain.

RESULTS

Scopolamine-induced cognitive dysfunction was significantly attenuated by a single or sub-chronic administration of INM-176 in the passive avoidance and the Morris water maze tasks. A single or sub-chronic administration of INM-176 also ameliorated memory impairments induced by Aβ(1-42) protein. INM-176 inhibited acetylcholinesterase activity in the hippocampal tissue in vitro and ex vivo. In addition, INM-176 attenuated the Aβ(1-42) protein-induced astrocyte activation in the hippocampus as well as cholinergic neuronal damage in the CA3 region of the hippocampus and the nucleus basalis of Meynert.

CONCLUSION

These results suggest that the memory ameliorating effects of INM-176 on scopolamine- or Aβ(1-42) protein-induced memory impairment are mediated, in part, via acetylcholinesterase inhibition and neuroprotective activities.

Cognitive enhancing and antioxidant activity of ethyl acetate soluble fraction of the methanol extract of Hibiscus rosa sinensis in scopolamine-induced amnesia

Objective:

The objective of the present study was to evaluate the cognitive enhancing and antioxidant activity of Hibiscus rosa sinensis.

Materials and Methods:

The learning and memory was impaired by administration of scopolamine (1 mg/kg, i.p.) in mice which is associated with altered brain oxidative status. The object recognition test (ORT) and passive avoidance test (PAT) were used to assess cognitive enhancing activity. Animals were treated with an ethyl acetate soluble fraction of the methanol extract of H. sinensis (25, 50 and 100 mg/kg, p.o).

Results:

The ethyl acetate soluble fraction of the methanol extract of H. sinensis (EASF) attenuated amnesia induced by scopolamine and aging. The discrimination index (DI) was significantly decreased in the aged and scopolamine group in ORT. Pretreatment with EASF significantly increased the DI. In PAT, scopolamine-treated mice exhibited significantly shorter step-down latencies (SDL). EASF treatment showed a significant increase in SDL in young, aged as well as in scopolamine-treated animals. The biochemical analysis of brain revealed that scopolamine treatment increased lipid peroxidation and decreased levels of superoxide dismutase (SOD) and glutathione reductase (GSH). Administration of extract significantly reduced LPO and reversed the decrease in brain SOD and GSH levels. The administration of H. sinensis improved memory in amnesic mice and prevented the oxidative stress associated with scopolamine. The mechanism of such protection of H. sinensis may be due to augmentation of cellular antioxidants.

Conclusion:

The results of the present study suggested that H. sinensis had a protective role against age and scopolamine-induced amnesia, indicating its utility in management of cognitive disorders.

Prevention of scopolamine-induced memory deficits by schisandrin B, an antioxidant lignan from Schisandra chinensis in mice

The preventive effect of schisandrin B (Sch B), an antioxidant ingredient of Schisandra chinensis, was studied on scopolamine-induced dementia in mouse. Scopolamine developed oxidative stress in the brain with the decreased levels of antioxidant enzymes and increased nitrite level. At the same time, a significant impairment of learning and memory occurred when evaluated by passive avoidance task (PAT) and Morris water maze (MWM) with concomitant increase of acetylcholinesterase (AChE) activity and decreased acetylcholine levels. Pre-treatment by Sch B (10, 25, 50 mg/kg) effectively prevented scopolamine-induced oxidative stress and improved behavioural tasks. Further, the scopolamine-induced increase in AChE activity was significantly suppressed and the level of acetylcholine was maintained as normal by Sch B treatment. These results suggest that Sch B have protective function against cerebral functional defects such as dementia not only by antioxidant prevention but also exerting its potent cognitive-enhancing activity through modulation of acetylcholine level.

Schisandrin enhances dendrite outgrowth and synaptogenesis in primary cultured hippocampal neurons

BACKGROUND

Schisandra chinensis, commonly used in Asia for tea material and traditional Chinese medicine, is presumed to enhance mental and intellectual functions. In this study, the effects and signalling mechanisms of a purified compound schisandrin, one of the lignan of Schisandra chinensis, on primary cultured hippocampal neurons were investigated.

RESULTS

Schisandrin treatment enhanced total dendritic length and branching complexity, both of which were significantly suppressed in the presence of specific blockers for calmodulin-dependent kinase II (CaMKII), protein kinase C epsilon (PKCε), and mitogen activated protein kinase kinase (MEK). Moreover, schisandrin induced calcium influx, and phosphorylation of CaMKII, PKCε, and MEK. Inhibition of CAMKII and PKCε attenuated the schisandrin-induced phosphorylation of PKCε and MEK, and the phosphorylation of MEK, respectively. Moreover, schisandrin also stimulated the phosphorylation of cyclic AMP responsive-element binding protein (CREB) at Ser-133, an effect that was blocked by KN93. In addition to its neuritogenic effects, schisandrin increased the numbers of postsynaptic density-95-positive and FM1-43-positive puncta in dendrites and synaptic boutons, respectively.

CONCLUSION

In hippocampal neurons, schisandrin exhibits neurotrophic properties that are mediated by the CaMKII-PKCε-MEK pathway.

Effect of wild ginseng on scopolamine-induced acetylcholine depletion in the rat hippocampus

Objectives

The ameliorating effects of wild ginseng on learning and memory deficits were investigated in rats.

Methods

Rats were treated daily with wild ginseng or cultivated ginseng for 7 days at 30 min before scopolamine injection (2 mg/kg, i.p.). After inducing cognitive impairment by the administration of scopolamine, behavioural assessment using the Morris water maze was performed. Changes in cholinergic system reactivity were also examined by measuring the immunoreactive neurons of choline acetyltransferase and the reactivity of acetylcholinesterase in the hippocampus.

Key findings

Scopolamine injection induced impaired performance in the water maze test and severe cell losses in hippocampal cholinergic neurons, as indicated by decreased choline acetyltransferase immunoreactivity and increased acetylcholinesterase reactivity. Daily administration of wild ginseng produced a significant improvement in the escape latency for finding the platform in the Morris water maze and reduced the loss of cholinergic immunoreactivity in the hippocampus. The reduced expression of brain-derived neurotrophic factor mRNA due to the scopolamine injection was recovered to normal levels by the administration of wild ginseng.

Conclusions

Wild ginseng demonstrates a significant neuroprotective effect against scopolamine-induced neuronal and cognitive impairment.

Free and Easy Wanderer Plus (FEWP), a polyherbal preparation, ameliorates PTSD-like behavior and cognitive impairments in stressed rats

Free and Easy Wanderer Plus (FEWP) is a well-known traditional Chinese medicine that has been shown to be effective in treating various mood disorders. The purpose of the present study was to determine whether FEWP could ameliorate stress-associated behavior in rats. Following the exposure to enhanced single prolonged stress (ESPS) paradigm, consisting of 2-hr constraint, 20-min forced swimming, ether-induced loss of consciousness, and an electric foot shock, animals were administered orally with FEWP (2.5, 5, or 10mg/kg daily) or vehicle for 2 weeks. Animals were then tested in the open field, elevated plus-maze, and Morris water maze. ESPS exposure resulted in pronounced anxiety-like behavior, without impairing locomotor activity, as indicated by significant decreases of time spent and number of entries into open arms in the elevated plus-maze test, and unaltered distance traveled in the open field test compared to unexposed animals. ESPS-exposed animals also displayed marked cognitive impairments, with significant increases of distance traveled and the escape latency to the underwater platform, and a striking decrease of time spent in the target quadrant with and without the removal of the platform in the water maze test. However, repeated treatment with FEWP, particularly at higher doses, reversed the aforementioned behavioral values in the elevated plus-maze and water maze tests to the levels similar to unexposed animals. These results indicate that FEWP possesses anxiolytic and cognition-improving effects and may be an effective herbal preparation for the treatment of stress-associated conditions, such as posttraumatic stress disorder (PTSD).

Loganin improves learning and memory impairments induced by scopolamine in mice

Loganin is an iridoid glycoside found in the Flos lonicerae, Fruit cornus, and Strychonos nux vomica. We investigated the effect of loganin on learning and memory impairments induced by scopolamine (0.5mg/kg, i.p.), a muscarinic antagonist, using the Y-maze, passive avoidance, and the Morris water maze tests in mice. In the Y-maze test, loganin (40 mg/kg, p.o.) significantly improved the scopolamine-induced memory impairment. In addition, loganin (20 and 40 mg/kg, p.o.) significantly reversed scopolamine-induced impairments measured by the passive avoidance and the Morris water maze tests. A day after the last trial session of the Morris water maze test (probe trial session), loganin (20 and 40 mg/kg) dose-dependently increased the latency time in the target quadrant. Furthermore, loganin significantly inhibited acetylcholinesterase activity in the hippocampus and frontal cortex. Loganin may have anti-amnesic activity that may hold significant therapeutic value in alleviating certain memory impairments observed in Alzheimer's disease.

Protective effect of the ethanol extract of Magnolia officinalis and 4-O-methylhonokiol on scopolamine-induced memory impairment and the inhibition of acetylcholinesterase activity

Magnolol, honokiol, and obovatol are well-known bioactive constituents of the bark of Magnolia officinalis and have been used as traditional Chinese medicines for the treatment of neurosis, anxiety, and stroke. We recently isolated novel active compound (named 4-O-methylhonokiol) from the ethanol extract of Magnolia officinalis. The present study aimed to test two different doses of ethanol extracts of Magnolia officinalis (5 and 10 mg/kg/mouse, p.o., 1 week) and 4-O-methylhonokiol (0.75 and 1.5 mg/kg/mouse, p.o., 1 week) administered for 7 days on memory impairment induced by scopolamine (1 mg/kg body weight i.p.) in mice. Memory and learning were evaluated using the Morris water maze and the step-down avoidance test. Both the ethanol extract of Magnolia officinalis and 4-O-methylhonokiol prevented memory impairment induced by scopolamine in a dose-dependent manner. The ethanol extract of Magnolia officinalis and 4-O-methylhonokiol also dose-dependently attenuated the scopolamine-induced increase of acetylcholinesterase (AChE) activity in the cortex and hippocampus of mice, and inhibited AChE activity in vitro with IC₅₀ (12 nM). This study, therefore, suggests that the ethanol extract of Magnolia officinalis and its major ingredient, 4-O-methylhonokiol, may be useful for the prevention of the development or progression of AD.

Neuroprotective effects of Dioscorea opposita on scopolamine-induced memory impairment in in vivo behavioral tests and in vitro assays

ETHNOPHARMACOLOGICAL RELEVANCE

Plants belong to the genus Dioscorea have long been used as edible tuber crops in many tropical and subtropical areas and as a traditional herbal medicine in oriental countries including China, Japan and Korea.

AIM OF THE STUDY

In this study, in vivo and in vitro tests were carried out to evaluate the cognitive enhancing effects of CHCl(3)-soluble extract from Dioscorea opposita against scopolamine-induced amnesic mice and glutamate- and H(2)O(2)-treated cortical neurons of rats.

MATERIALS, METHODS AND RESULTS

Acute treatment (200 mg/kg body weight, p.o.) and 10 days' daily administration (50 mg/kg body weight, p.o.) of CHCl(3)-soluble extract showed significant spatial learning and memory improvement on mice. Furthermore, the neuroprotective effects on glutamate- and H(2)O(2)-induced neurotoxicity in primary cultured cortical neurons of rats were assessed. Pretreatment with the extract was found to impart significant protection against neurotoxicity.

CONCLUSIONS

These in vivo and in vitro results suggest that the Dioscorea opposita has neuroprotective effects on memory impairment related neurodegenerative diseases.

Wuweizisu C from Schisandra chinensis decreases membrane potential in C6 glioma cells

AIM

To study the effects of dibenzocyclooctadiene lignans isolated from Schisandra chinensis, such as wuweizisu C, gomisin N, gomisin A, and schisandrin, on the membrane potential in C6 glioma cells.

METHODS

The membrane potential was estimated by measuring the fluorescence change in DiBAC-loaded glioma cells.

RESULTS

Wuweizisu C decreased the membrane potential in a concentration-dependent manner. Gomisin N and gomisin A, however, showed differential modulation and no change was induced by schisandrin or dimethyl- 4,4'-dimethoxy-5,6,5',6'-dimethylene dioxybiphenyl-2,2'-dicarboxylate, a synthetic drug derived from dibenzocyclooctadiene lignans. We found no involvement of G(i/o ) proteins, phospholipase C, and extracellular Na(+) on the wuweizisu C-induced decrease of the membrane potential. Wuweizisu C by itself did not change the intracellular Ca(2+)[Ca(2+)](i) concentration, but decreased the ATP-induced Ca(2+) increase in C6 glioma cells. The 4 lignans at all concentrations used in this study did not induce any effect on cell viability. Furthermore, we found a similar decrease of the membrane potential by wuweizisu C in PC12 neuronal cells.

CONCLUSION

Our results suggest that the decrease in the membrane potential and the modulation of [Ca(2+)](i) concentration by wuweizisu C could be important action mechanisms of wuweizisu C.

Water-soluble derivative of propolis mitigates scopolamine-induced learning and memory impairment in mice

The water-soluble derivative of propolis (WSDP) was prepared from fresh Chinese propolis. Its major constituents were identified by high performance liquid chromatography (HPLC) analysis. It has been reported that propolis possessed a broad spectrum of biological activities but including few studies on learning and memory by now. Thus, this study was aimed to investigate the effect of WSDP on scopolamine-induced learning and memory impairment in mice. WSDP (50 mg/kg, 100 mg/kg) was given by intragastric administration (i.g.) 40 min prior to the intraperitoneal (i.p.) injection of scopolamine (1 mg/kg). The effect on amnesia was investigated with both hidden-platform acquisition training and probe trial testing in Morris water maze test. The results from 100 mg/kg WSDP group showed significant mitigation scopolamine-induced amnesia in mice. Furthermore, WSDP's effect on the acetylcholinesterase (AChE) activity in the cerebral cortex and hippocampus was also assayed. As a result, WSDP (100 mg/kg) significantly inhibited AChE activity in the hippocampus of scopolamine-treated mice. These results indicated that WSDP may mitigate amnesia in vivo through inhibition of AChE activity in the hippocampus, which suggested propolis may have potential as a pharmaceutical of brain protection with elderly population for preventing Alzheimer's disease (AD) and other neurodegenerative diseases.

Aqueous and hydroalcoholic extracts of Black Maca (Lepidium meyenii) improve scopolamine-induced memory impairment in mice

Lepidium meyenii Walp. (Brassicaceae), known as Maca, is a Peruvian hypocotyl growing exclusively between 4,000 and 4,500 m altitude in the central Peruvian Andes, particularly in Junin plateau. Previously, Black variety of Maca showed to be more beneficial than other varieties of Maca on learning and memory in ovariectomized mice on the water finding test. The present study aimed to test two different doses of aqueous (0.50 and 2.00 g/kg) and hydroalcoholic (0.25 and 1.00 g/kg) extracts of Black Maca administered for 35 days on memory impairment induced by scopolamine (1mg/kg body weight i.p.) in male mice. Memory and learning were evaluated using the water Morris maze and the step-down avoidance test. Brain acetylcholinesterase (AChE) and monoamine oxidase (MAO) activities in brain were also determined. Both extracts of Black Maca significantly ameliorated the scopolamine-induced memory impairment as measured in both the water Morris maze and the step-down avoidance tests. Black Maca extracts inhibited AChE activity, whereas MAO activity was not affected. These results indicate that Black Maca improves scopolamine-induced memory deficits.

Acetylcholinesterase inhibitory effect of lignans isolated fromSchizandra chinensis

The hexane extract of the fruit of Schizandra chinensis (Schisandraceae) was found to show significant inhibition of the activity of acetylcholinesterase enzyme (AChE). In further studies, fourteen lignans were isolated, and evaluated for their inhibitory effect on AChE. The compounds having both aromatic methylenedioxy and hydroxyl groups on their cyclooctadiene ring, such as gomisin C (6), gomisin G (7), gomisin D (8), schisandrol B (11) and gomisin A (13), entirely inhibited AChE in dose dependent manners, with IC50 values of 6.71 +/- 0.53, 6.55 +/- 0.31, 7.84 +/- 0.62, 12.57 +/- 1.07 and 13.28 +/- 1.68 microM, respectively. These results indicate that the lignans could potentially be a potent class of AChE inhibitors.

Effect of Tremella fuciformis on the neurite outgrowth of PC12h cells and the improvement of memory in rats

We investigated the neuritogenic effects of Tremella fuciformis (TF), which has been valued in traditional Chinese medicine as a remedy with nutritive and tonic actions, on PC12h cells. The cognitive improving effects of TF on scopolamine-induced (2 mg/kg, s.c.) amnesia in rats were also evaluated with using the Morris water maze task and by performing choline acetyltransferase (ChAT) immunohistochemistry. The water extract of TF (0.01-1 microg/ml) promoted neurite outgrowth of the PC12h cells in a dose dependent manner. TF was highly efficient at the concentration range of 0.1-1 microg/ml. Oral daily treatment with TF (100 or 400 mg/kg) for 14 consecutive days significantly reversed the scopolamine-induced deficit in learning and memory, and it alleviated decrease in cholinergic immunoreactivity induced by scopolamine in the medial septum and hippocampus. The results demonstrate that the promotion of neuritogenesis in neuronal culture cells by TF water extract is related with its activity for improving the performance of rats on a spatial learning and memory task. Moreover, the impairments of spatial learning and memory may be attributable to the decrease in activation of the septohippocampal cholinergic system and that TF ameliorated learning and memory deficits partly through its increasing the central cholinergic activity. Therefore, TF could represent a potentially useful agent that is able to improve the function of impaired cognitive processes.

Alzheimer's Disease Drug Discovery from Herbs: Neuroprotectivity from β-Amyloid (1-42) Insult

OBJECTIVE

To comparatively evaluate selected herbs for their ability to protect neuronal cells from direct betaA(1-42) insult.

DESIGN

Twenty-seven (27) herbs were selected, extracted with aqueous methanol (90%) and chloroform, and the extracts were evaluated for their ability to protect PC12 rat pheochromocytoma and primary neuronal cells from betaA(1-42) insult using both 3-[4,5-dimethylthiazol-2-yl]-2,5-diphenyltetrazolium bromide reduction assay and lactate dehydrogenase efflux assay.

RESULTS

Curcuma aromatia (ul-keum) and Zingiber officinale (ginger) extracts effectively protected cells from betaA(1-42) insult, followed by Ginkgo biloba (ginkgo), Polygonatum sp. (King Solomon's seal), Cinnamum cassia (Chinese cinnamon), Rheum coreanum (Korean rhubarb), Gastrodia elata (gastrodia), and Scutellaria baicalensis (skullcap). Several extracts showed cytotoxicity at high concentration (approximately 150 microg/mL), whereas other extracts did not at all protect cells from betaA(1-42) insult.

CONCLUSION

Selective herbs may be potentially important resources to discover drug candidates against the onset of Alzheimer's disease.

Natural drug extracts for a nutritive-tonic drink, promotes the induction of long-term potentiation in rat hippocampal dentate gyrus in vivo

We have shown previously that oral administration of a nutritive-tonic drink (NTD) improves scopolamine-induced memory impairment in the passive avoidance task and Morris water-maze in mice and that this action is attributable to the natural drug extracts, rather than synthetic drugs such as taurine and caffeine, in the NTD. In order to investigate the mechanism underlying the antiamnesic effects of the natural drug extracts, the effects of the extracts on the induction of long-term potentiation (LTP) was investigated in the dentate gyrus (DG) of normal and scopolamine-treated rats. Oral administration of natural drug extracts enhanced the induction of population spike amplitude induced by weak tetanic stimulation (30 pulses at 60 Hz). Scopolamine (0.3 mg/kg, i.p.) completely inhibited the induction of LTP induced by both weak and strong tetanic stimulation (100 pulses at 100 Hz). Natural drug extracts enhanced partially but significantly the induction of LTP by strong tetanus, but had a very weak effect on that induced by weak tetanus. These results suggest that LTP induced by strong tetanus is sensitive to natural drug extracts, and that the antiamnesic effect of the NTD is at least partly attributable to the LTP-improving effect of the natural drug extracts in the DG.

Gomisin A improves scopolamine-induced memory impairment in mice

Gomisin A is a component of the fruits of Schizandra chinesis which are widely used as a tonic in traditional Chinese medicine. In the present study, we assessed the effect of gomisin A on the learning and memory impairments induced by scopolamine. The cognition-enhancing effect of gomisin A was investigated using a passive avoidance test, the Y-maze test, and the Morris water maze test in mice. Drug-induced amnesia was induced by treating animals with scopolamine (1 mg/kg, i.p.). Gomisin A (5 mg/kg, p.o.) administration significantly reversed scopolamine-induced cognitive impairments in mice by the passive avoidance test and the Y-maze test (P<0.05), and also improved escape latency in the Morris water maze test at 5 mg/kg (P<0.05). Moreover, in an in vitro study, gomisin A was found to inhibit acetylcholinesterase activity in a dose-dependent manner (IC50 value; 15.5 microM). These results suggest that gomisin A may be a useful cognitive impairment treatment, and its beneficial effects are mediated, in part, via enhancing the cholinergic nervous system.

The Effects of BR003 on Memory and Cell Proliferation in the Dentate Gyrus of Rat Hippocampus

BR003 is a multi-herbal formula that contains twelve medicinal herbs. We investigated the effects of oral administration of BR003 to Wistar rats on (a) learning and memory using a passive avoidance test and (b) cell proliferation in the dentate gyrus (DG) of the hippocampus using immunohistochemical analysis of 5-bromo-2-deoxyuridine (BrdU) expression. In the passive avoidance test, the retention time of the BR003-treated group was significantly longer than that of the control group (182.64+/-39.88 vs. 73.08+/-29.30 s, respectively; n=11; p<0.05). There were significantly more BrdU-immunoreactive cells in the DG in the BR003-treated group than in the control group (1281.07+/-151.16 vs. 818.01+/-132.98 cells per DG, respectively; n=11; p<0.05). These results suggest that the administration of BR003 not only improves learning and memory but also increases cell proliferation in the DG of the rat hippocampus.

Can herbs provide a new generation of drugs for treating Alzheimer's disease?

The overall aim of this review is to discuss cellular mechanisms at work in the progression of AD and current therapeutic strategies for treating AD, with a focus on the potential efficacy of herbal treatments. Recent advances in molecular, cellular, and animal model studies have revealed that formation of the 4-kDa amyloid beta peptide is a key factor in the development and progression of AD. Several cellular changes have been identified that are related to amyloid beta plaques and neurofibrillary tangles found in the autopsied brains of AD patients and in AD animal models. Several therapeutic strategies have been developed to treat AD, including anti-inflammatory, anti-oxidant, and anti-amyloid approaches. Recently, herbal treatments have been tested in animal and cellular models of AD and in clinical trials with AD subjects. In AD animal models and cell models, herbal extracts appear to have fewer adverse effects than beneficial effects on A beta and cognitive functions. These extracts have multi-functional properties (pro-cholinergic, anti-oxidant, anti-amyloid, and anti-inflammatory), and their use in the treatment of AD patients looks promising. The chemical compositions of herbs and their potential for alleviating or reducing symptoms of AD or for affecting the disease mechanism need to be further studied.