Polygalae Radix: review of metabolites, pharmacological activities and toxicology

Polygalae Radix: is the dried root of Polygala tenuifolia Willd. or Polygala sibirica L., which has the effect of improving memory and cognitive function in traditional Chinese medicine. Modern pharmacological studies indicated that Polygalae Radix has rich pharmacological activities in vitro and in vivo, including protective effects on the nervous system, immune system, cardiovascular system and respiratory system, as well as antioxidant and antiepileptic pharmacological activities. Up to now, more than 160 metabolites from Polygalae Radix were identified, including triterpenoid saponins, xanthones, oligosaccharide esters and et al. The clinical practice of traditional Chinese medicine has proved that Polygalae Radix has a certain irritation to the throat, and a large or long-term use will stimulate the digestive tract, and the main toxic metabolite is saponins. Therefore, Polygalae Radix should be pr ocessed or used in combination with other Chinese herbal medicines to reduce the irritation to the throat and reduce gastrointestinal irritation. This article provides a review of the metabolites, pharmacological activity, and toxicology of Polygalae Radix. It also discusses the future research prospects and existing problems of Polygalae Radix, providing reference for further research on Polygalae Radix.

Acupuncture activates IRE1/XBP1 endoplasmic reticulum stress pathway in Parkinson's disease model rats

Acupuncture has demonstrated its efficacy as a treatment for Parkinson's disease (PD). Thus, the objective of this study was to investigate the potential mechanisms underlying acupuncture's effects on PD treatment. Our approach involved several steps. Firstly, we assessed the behavioral changes in PD rats, the modulation of dopamine (DA) and 5-hydroxytryptamine (5-HT) levels in the striatum, as well as the alteration in α-synuclein (α-syn) levels in the midbrain, aiming to evaluate the efficacy of acupuncture in PD treatment. Secondly, we selected endoplasmic reticulum (ER) stress inhibitors and activators to assess the impact of ER stress on PD rats. Lastly, we utilized an IRE1 inhibitor to observe the influence of acupuncture on the IRE1/XBP1 pathway in PD rats. The findings of this study revealed that acupuncture improved the autonomous motor function, balance ability, coordination, and sensory motor integration function in the PD model rats. Additionally, it increased the levels of DA and 5-HT in the striatum while decreasing the levels of α-syn in the midbrain. Acupuncture also activated the expression of ER stress in the midbrain and upregulated the expression of IRE1/XBP1 in the striatum of PD model rats. Based on these results, we concluded that acupuncture may enhance the behavior of PD rats by activating the IRE1/XBP1 ER stress pathway, associated with the reduction of midbrain α-syn expression and the increase in striatal DA and 5-HT levels in unilateral 6-OHDA lesioned rats.

Elucidating the promising role of traditional Chinese medicine in neuroprotection against oxidative stress encompassing Alzheimer's disease

Medicinal plants are being used from time immemorial for their therapeutic benefits and have immense value in the therapy of neurodegenerative disorders. One of the most important neurological disorders is Alzheimer's disease (AD) which is a major contributor to dementia and is accompanied by abundant oxidative stress in the brain tissue. A critical pathway to target the increased oxidative stress is to administer agents with antioxidant potential. Despite currently available clinical treatments to treat AD such as cholinesterase inhibitors or NMDA antagonists which address only the symptoms and cannot hamper disease progression, no efficient available clinical treatment can break the vicious cycle of oxidative stress and neurodegeneration till date. The main objective of presenting this review is that traditional Chinese medicine (TCM) acts as a promising candidate in breaking this vicious cycle and improves the quality of life of the debilitating patients. The active constituents of various herbs in TCM including Angelica sinensis, Radix polygalae, Polygala tenuifolia, and members of the Lamiaceae family have acquired experience of managing oxidative stress as indicated in the review for more than a thousand years now, and the preclinical and clinical evidence of their therapeutic potential has been highlighted in the review. Most importantly, Chinese herbs provide a multiple-target approach rather than a single-target approach and thus can target multiple pathways involved in AD at once. The Chinese herbs can definitely untangle the issues in the current therapy regimen of AD.

Efficacy of Ninjin'yoeito in treating severe coronavirus disease 2019 in patients in an intensive care unit

Coronavirus Disease-2019 (COVID-19), an infectious disease associated with severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2), is a global emergency with high mortality. There are few effective treatments, and many severe patients are treated in an intensive care unit (ICU). The purpose of this study was to evaluate whether the Japanese Kampo medicine ninjin'yoeito (NYT) is effective in treating ICU patients with COVID-19. Nine patients with confirmed SARS-CoV-2 infection admitted to the ICU were enrolled in this study. All patients underwent respiratory management with invasive mechanical ventilation (IMV) and enteral nutrition. Four patients received NYT (7.5 g daily) from an elemental diet tube. We retrospectively examined the prognostic nutritional index (PNI), length of IMV, length of ICU stay, length of hospital stay, rate of tracheostomy, and mortality rate. The median age of the enrolled participants was 60.0 years (4 men and 5 women). The median body mass index was 27.6. The most common comorbidity was diabetes (4 patients, 44%), followed by hypertension (3 patients, 33%) and chronic kidney disease (2 patients, 22%). The median length of IMV, ICU stay, and hospital stay were all shorter in the NYT group than in the non-NYT group (IMV; 4.0 days vs 14.3 days, ICU; 5.3 days vs 14.5 days, hospital stay; 19.9 days vs 28.2 days). In the NYT and non-NYT groups, the median PNI at admission was 29.0 and 31.2, respectively. One week after admission, the PNI was 30.7 in the NYT group and 24.4 in non-NYT group. PNI was significantly (p = 0.032) increased in the NYT group (+13.6%) than in the non-NYT group (-22.0%). The Japanese Kampo medicine NYT might be useful for treating patients with severe COVID-19 in ICU. This study was conducted in a small number of cases, and further large clinical trials are necessary.

Study on the safety of Polygala tenuifolia Willdenow root extract powder (BT-11) in young person aged from 9 to 19 years old

ETHNOPHARMACOLOGICAL RELEVANCE

Polygala tenuifolia Willdenow root extract (BT-11) has beneficial effects on central nervous system disorders in human. The safety of BT-11 should be elucidated in younger person further.

AIM OF THE STUDY

To evaluate the safety of BT-11 in human aged from 9 to 19 years old.

MATERIAL AND METHODS

The safety was evaluated in randomly assigned subjects who received the test products (61 subjects in BT-11 300 mg daily or 60 subjects in matching placebo) for 12 weeks. Adverse reactions were analyzed by the incidence rate, type, and severity. The clinical examination included hematology and blood chemistry tests, urinalysis, vital signs, body weight, and electrocardiogram (ECG).

RESULTS

Eleven adverse reactions were observed in ten subjects receiving BT-11 while seven adverse reactions in six subjects receiving placebo. There were no statistical differences in the incidence of adverse reactions between the two groups. Serious adverse reactions such as acute appendicitis and acute viral gastroenteritis were observed in the BT-11 group4 and the placebo group, respectively. However, it was confirmed that they were not associated with the test product. All other adverse reactions observed during the test period were resolved completely without special treatment. No statistical difference was also observed in safety laboratory tests, vital signs, and ECG between two groups.

CONCLUSIONS

This study demonstrates the safety of BT-11 in the adolescent by showing no apparent adverse reactions related to it.

The Protective Effects of PSM-04 Against Beta Amyloid-Induced Neurotoxicity in Primary Cortical Neurons and an Animal Model of Alzheimer's Disease

Polygala tenuifolia Willdenow is a herb known for its therapeutic effects in insomnia, depression, disorientation, and memory impairment. In Alzheimer's disease (AD) animal model, there has been no report on the effects of memory and cognitive impairment. PSM-04, an extract from the root of P. tenuifolia Willdenow, was developed with improved bioabsorption. The present study aimed to investigate the neuroprotective effects of PSM-04 on AD and reveal the possible molecular mechanism. The neuroprotective effect of PSM-04 in primary cortical neurons treated with L-glutamate, oligomeric Aβ, or H2O2. PSM-04 exhibited significant neuroprotective effects against neurotoxicity induced by L-glutamate or oligomeric Aβ was studied. PSM-04 exhibited significant neuroprotective effects against neurotoxicity induced by L-glutamate or oligomeric Aβ. Oxidative stress induced by ROS was monitored using the DCF-DA assay, and apoptosis was assessed using the TUNEL assay in primary cortical neurons treated with H2O2 or oligomeric Aβ. PSM-04 also decreased oxidative stress induced by H2O2 and apoptotic cell death induced by oligomeric Aβ. We evaluated the therapeutic effect of PSM-04 in 5xFAD (Tg) mice, an animal model for AD. PSM-04 was orally administered to 4-month-old 5xFAD mice for 2 months. To confirm the degree of cognitive impairment, a novel object recognition task was performed. The treatment with PSM-04 significantly alleviated cognitive impairments in Tg mice. In addition, amyloid plaques and gliosis decreased significantly in the brains of PSM-04-administered Tg mice compared with Tg-vehicle mice. Furthermore, the administration of PSM-04 increased the superoxide dismutase-2 (SOD-2) protein level in hippocampal brain tissues. Our results indicated that PSM-04 showed therapeutic effects by alleviating cognitive impairment and decreasing amyloid plaque deposition in Tg mice. Therefore, PSM-04 was considered as a potential pharmacological agent for neuroprotective effects in neurodegenerative diseases, including AD.

1,3,7-Trihydroxyxanthone, derived from Polygalae Radix, a herbal medicine, stimulates the expression of neurotrophic factors in rat astrocyte primary cultures via cAMP- and ERK-dependent pathways

1,3,7-Trihydroxyxanthone is a compound isolated from Polygalae Radix, a medicinal herb frequently applied for treatment of psychiatric disordres with symptoms of forgetfulness and depression in ancient China. In current research, this compound was applied onto rat astrocyte primary cultures in exploring the action mechanisms of 1,3,7-trihydroxyxanthone on regulating synthesis of neurotrophic factors. It was found that 1,3,7-trihydroxyxanthone could significantly stimulate the expression of NGF and BDNF in dose-dependent manners: the stimulation was both in mRNA and protein levels. Furthermore, 1,3,7-trihydroxyxanthone might fulfill this effect by regulating critical enzymes, such as plasminogen, tissue plasminogen activator, neuroserpin and tissue inhibitor of metalloproteinases in metabolic pathway of neurotrophic factors. Besides, inhibitors of cAMP- and ERK-dependent pathways, which implied the possible signaling pathway, could reverse this inducing effect. These results might support the potentiality of 1,3,7-trihydroxyxanthone in drug development in treating psychiatric disorders.

Polygalae Radix Extract Prevents Axonal Degeneration and Memory Deficits in a Transgenic Mouse Model of Alzheimer's Disease

Memory impairments in Alzheimer's disease (AD) occur due to degenerated axons and disrupted neural networks. Since only limited recovery is possible after the destruction of neural networks, preventing axonal degeneration during the early stages of disease progression is necessary to prevent AD. Polygalae Radix (roots of Polygala tenuifolia; PR) is a traditional herbal medicine used for sedation and amnesia. In this study, we aimed to clarify and analyze the preventive effects of PR against memory deficits in a transgenic AD mouse model, 5XFAD. 5XFAD mice demonstrated memory deficits at the age of 5 months. Thus, the water extract of Polygalae Radix (PR extract) was orally administered to 4-month-old 5XFAD mice that did not show signs of memory impairment. After consecutive administrations for 56 days, the PR extract prevented cognitive deficit and axon degeneration associated with the accumulation of amyloid β (Aβ) plaques in the perirhinal cortex of the 5XFAD mice. PR extract did not influence the formation of Aβ plaques in the brain of the 5XFAD mice. In cultured neurons, the PR extract prevented axonal growth cone collapse and axonal atrophy induced by Aβ. Additionally, it prevented Aβ-induced endocytosis at the growth cone of cultured neurons. Our previous study reported that endocytosis inhibition was enough to prevent Aβ-induced growth cone collapse, axonal degeneration, and memory impairments. Therefore, the PR extract possibly prevented axonal degeneration and memory impairment by inhibiting endocytosis. PR is the first preventive drug candidate for AD that inhibits endocytosis in neurons.

3,4,5-Trimethoxycinnamic acid, one of the constituents of Polygalae Radix exerts anti-seizure effects by modulating GABAAergic systems in mice

Polygalae Radix is an important medicinal plant that is widely used in most of Africa. 3,4,5-Trimethoxycinnamic acid (TMCA) is one of the constituents of Polygalae Radix. Until now, the mechanisms involved in the anti-seizure property of TMCA are still unclear. We examined the anti-seizure effect of TMCA. TMCA administered at doses of 5, 10 and 20 mg/kg and evaluated anti-seizure effects by maximal electroshock (MES) and pentylenetetrazol (PTZ) models in mice. TMCA administered at doses of 10 and 20 mg/kg significantly reduced the incidence of MES-induced tonic hindlimb extension (THE). TMCA significantly delayed the onset of myoclonic jerks (MJ), and decreased the seizure severity and mortality compared with the vehicle-treated animals in PTZ seizure model. TMCA 10 and 20 mg/kg treated groups also did not determined generalized clonic seizures (GCS). Pretreatment with a GABAA/benzodiazepine (BZ) receptor antagonist flumazenil blocked the anti-seizure effects of TMCA. These data support the further investigation of TMCA as a GABAA/BZ receptor agonist for anti-seizure therapy.

Preclinical Safety of the Root Extract of Polygala tenuifolia Willdenow in Sprague-Dawley Rats and Beagle Dogs

The root of Polygala tenuifolia Willdenow has been used for the treatment of insomnia, depression, and amnesia. However, the toxicological properties of the herb have been overlooked, because it has been used for a long time for various purposes. In this study, we evaluated the preclinical safety of the root extract in rats and beagle dogs. First, the acute oral toxicity was tested in both rats and dogs. In the rats, only one female of 2 g/kg died, but no treatment-related death or clinical and gross findings were observed after the administration. No toxicological changes or mortalities related to the test substance were also observed after the administration in the dogs. Although vomiting, discoloration, or hemorrhage was found in some dogs, there were no serious abnormalities. Second, the subchronic toxicity was investigated in the rats. Two animals were found dead in the female group of 1,000 mg/kg/day, but there were no abnormal findings associated with the test substance. There also were no adverse effects on the clinical signs, body weight, and hematological and biochemical findings. Therefore, our results showed that the acute or subchronic toxicity of the root extract of Polygala tenuifolia might not be toxic to rats and dogs.

Dehydroevodiamine·HCl Improves Stress-Induced Memory Impairments and Depression Like Behavior in Rats

Dehydroevodiamine·HCl (DHED) has been reported to prevent memory impairment and neuronal cell loss in a rat model with cognitive disturbance. We investigated the effect of DHED on memory impairment and behavioral abnormality caused by stress. We demonstrated that DHED can improve stress-induced memory impairments and depression-like behaviors by using open-field test, Y-maze test and forced swimming test. DHED treatment significantly recovered the decreases in the levels of neural cell adhesion molecule (NCAM) proteins caused by stress and the decreases in cell viability. Our results suggested that DHED is a potential drug candidate for neuronal death, memory impairment and depression induced by stress.

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.

Tenuigenin attenuates α-synuclein-induced cytotoxicity by down-regulating polo-like kinase 3

BACKGROUND AND AIMS

Tenuigenin (Ten) is a Chinese herbal extract with antioxidative and antiinflammatory effects on toxin-induced cell models of Parkinson's disease (PD); however, its effects on α-synuclein toxicity-based PD models remain unknown. α-synuclein hyperphosphorylation is a key event in PD pathogenesis and potential target of therapeutic interventions. We tested whether Ten alleviates α-synuclein-induced cytotoxicity via reducing kinases that phosphorylate α-synuclein.

METHODS

SH-SY5Y cells transiently transfected with wild-type or A53T mutant α-synuclein were used to evaluate the effect of Ten on the levels of α-synuclein phosphorylation-related kinases. Cells treated with 10 μM Ten for 24 h were measured for viability (proliferation and apoptosis assays) and cellular proteins harvested and fractioned. The levels of total and phosphorylated α-synuclein and five associated kinases (polo-like kinase [PLK] 1-3, casein kinase [CK] 1-2) were evaluated by Western blotting.

RESULTS

Overexpression of either wild-type or A53T mutant α-synuclein decreased cell viability and increased α-synuclein phosphorylation. Ten treatment-protected cells from this α-synuclein-induced toxicity and dramatically reduced α-synuclein phosphorylation and PLK3 (but not other kinase) levels.

CONCLUSION

In α-synuclein cell model of PD, Ten is effective in attenuating α-synuclein-induced toxicity and α-synuclein phosphorylation probably via targeting PLK3, suggesting it could be an efficient therapeutic drug to treat α-synuclein-related neurodegeneration.

Tenuigenin protects dopaminergic neurons from inflammation-mediated damage induced by the lipopolysaccharide

BACKGROUND

Parkinson's disease (PD) is a neurodegenerative disorder characterized by progressive death of dopaminergic neurons in the substantia nigra pars compacta (SNpc).

AIMS

To study if tenuigenin (TEN), the main active component of Polygala tenuifolia, can protect dopaminergic neurons from inflammation-mediated damage in vivo.

METHODS

We observed the effects of TEN on lipopolysaccharide (LPS) induced PD model by behavioral analysis, high-performance liquid chromatography, immunohistochemistry and enzyme-linked immunoadsorbent assay, etc.

RESULTS

We showed that a single intranigral dose of LPSs (10 μg) induced microglial activation, reduced the survival ratio of tyrosine hydroxylase-immunoreactive (TH-ir) neurons in the SNpc and reduced dopamine (DA) content in the striatum. Treatment with 300 mg/kg TEN once per day over 14 weeks improved the survival rate of TH-ir neurons in the SNpc to 75%, on the non-injected side. Treatment with 200 or 300 mg/kg TEN once per day over 14 weeks significantly improved DA levels in the striatum to 73% and 81% on the non-injected side, respectively. The excessive production of cytokines, such as tumor necrosis factor (TNF)-α and interleukin (IL)-1β, was abolished by TEN administration.

CONCLUSION

Our results suggest that TEN may play a role in protecting dopaminergic neurons against inflammatory challenge.

Tenuigenin ameliorates learning and memory impairments induced by ovariectomy

Estrogen deficiency is associated with cognitive impairment. Hormone replacement therapy (HRT) has proven to be effective in preventing and reversing the memory and learning deficiencies. However, conventional estrogenic treatment could increase the risks of breast cancer and venous thromboembolism. Tenuigenin (TEN) is putatively believed as the active component extracted from a Chinese herb Polygala tenuifolia root. Although TEN has been shown to enhance learning and memory in healthy mice, it remains unknown whether or not TEN could ameliorate learning and memory impairments. In the present study, mice were divided into four groups: sham-operated (sham), ovariectomized (OVX), OVX+estradiol benzoate (EB) and OVX+TEN groups. Step-through passive avoidance and Y-maze tests were used to assess learning and memory abilities, and the number of nitric oxide synthase (NOS) positive neurons and the synaptic measurement of hippocampal CA1 area were examined. The results showed that TEN was given orally to OVX mice, leading to the improvement of learning and memory in step-through passive avoidance and Y-maze tests. TEN could reduce the loss of NOS positive neurons and prevent the synaptic morphological changes induced by ovariectomy. Our results suggest that TEN may exert a potential therapeutic value for menopause cognitive dysfunction.

Tenuigenin treatment improves behavioral Y-maze learning by enhancing synaptic plasticity in mice

Polygala tenuifolia root has been used to improve memory and cognitive function in Traditional Chinese Medicine for more than 2000 years. Since tenuigenin (TEN) is one of the most utilized P. tenuifolia root extracts, it is surprising there is no evidence for the effects of TEN on learning and memory so far. In the present study, we investigated the effects of TEN on learning and memory with Y-maze test in mice. We found that oral administration of 4mg/kg TEN significantly improved learning and memory in Y-maze task. Treatment with 4mg/kg TEN markedly reduced the acetylcholinesterase (AChE) activity and malondialdehyde (MDA) level, and increased superoxide dismutase (SOD) activity in hippocampus. In the electrophysiological test of hippocampal brain slice, 2μg/ml TEN perfusion substantially enhanced field excitatory postsynaptic potential (fEPSP) amplitude both in basic synaptic transmission and after high frequency stimulation (HFS) in Schaffer to CA1 pathway (Scha-CA1). These results indicate that TEN enhancing learning and memory may result from inhibiting AChE activity, improving antioxidation and enhancing synaptic plasticity in mice. Therefore, TEN shows promise as a potential nootropic product in improving learning and memory.

Promising therapeutics with natural bioactive compounds for improving learning and memory--a review of randomized trials

Cognitive disorders can be associated with brain trauma, neurodegenerative disease or as a part of physiological aging. Aging in humans is generally associated with deterioration of cognitive performance and, in particular, learning and memory. Different therapeutic approaches are available to treat cognitive impairment during physiological aging and neurodegenerative or psychiatric disorders. Traditional herbal medicine and numerous plants, either directly as supplements or indirectly in the form of food, improve brain functions including memory and attention. More than a hundred herbal medicinal plants have been traditionally used for learning and memory improvement, but only a few have been tested in randomized clinical trials. Here, we will enumerate those medicinal plants that show positive effects on various cognitive functions in learning and memory clinical trials. Moreover, besides natural products that show promising effects in clinical trials, we briefly discuss medicinal plants that have promising experimental data or initial clinical data and might have potential to reach a clinical trial in the near future.

Vulnerability of conditional NCAM-deficient mice to develop stress-induced behavioral alterations

Previous studies in rodents showed that chronic stress induces structural and functional alterations in several brain regions, including shrinkage of the hippocampus and the prefrontal cortex, which are accompanied by cognitive and emotional disturbances. Reduced expression of the neural cell adhesion molecule (NCAM) following chronic stress has been proposed to be crucially involved in neuronal retraction and behavioral alterations. Since NCAM gene polymorphisms and altered expression of alternatively spliced NCAM isoforms have been associated with bipolar depression and schizophrenia in humans, we hypothesized that reduced expression of NCAM renders individuals more vulnerable to the deleterious effects of stress on behavior. Here, we specifically questioned whether mice in which the NCAM gene is inactivated in the forebrain by cre-recombinase under the control of the calcium-calmodulin-dependent kinase II promoter (conditional NCAM-deficient mice), display increased vulnerability to stress. We assessed the evolving of depressive-like behaviors and spatial learning and memory impairments following a subchronic stress protocol (2 weeks) that does not result in behavioral dysfunction, nor in altered NCAM expression, in wild-type mice. Indeed, while no behavioral alterations were detected in wild-type littermates after subchronic stress, conditional NCAM-deficient mice showed increased immobility in the tail suspension test and deficits in reversal spatial learning in the water maze. These findings indicate that diminished NCAM expression might be a critical vulnerability factor for the development of behavioral alterations by stress and further support a functional involvement of NCAM in stress-induced cognitive and emotional disturbances.

Traditional chinese medicine for senile dementia

Traditional Chinese Medicine (TCM) has a 3000 years' history of human use. A literature survey addressing traditional evidence from human studies was done, with key result that top 10 TCM herb ingredients including Poria cocos, Radix polygalae, Radix glycyrrhizae, Radix angelica sinensis, and Radix rehmanniae were prioritized for highest potential benefit to dementia intervention, related to the highest frequency of use in 236 formulae collected from 29 ancient Pharmacopoeias, ancient formula books, or historical archives on ancient renowned TCM doctors, over the past 10 centuries. Based on the history of use, there was strong clinical support that Radix polygalae is memory improving. Pharmacological investigation also indicated that all the five ingredients mentioned above can elicit memory-improving effects in vivo and in vitro via multiple mechanisms of action, covering estrogen-like, cholinergic, antioxidant, anti-inflammatory, antiapoptotic, neurogenetic, and anti-Aβ activities. Furthermore, 11 active principles were identified, including sinapic acid, tenuifolin, isoliquiritigenin, liquiritigenin, glabridin, ferulic acid, Z-ligustilide, N-methyl-beta-carboline-3-carboxamide, coniferyl ferulate and 11-angeloylsenkyunolide F, and catalpol. It can be concluded that TCM has a potential for complementary and alternative role in treating senile dementia. The scientific evidence is being continuously mined to back up the traditional medical wisdom.

Polygalae radix inhibits toxin-induced neuronal death in the Parkinson's disease models

AIM OF THE STUDY

Polygalae radix, the root of Polygala tenuifolia Willd, has commonly been used for the treatment of amnesia and anxiety in traditional Korean medicine. The aim of this study was to investigate its neuroprotective effects and possible mechanisms of action in models of Parkinson's disease.

MATERIALS AND METHODS

This study utilized a 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assay, a reactive oxygen species (ROS) assay, a nitric oxide (NO) production assay, and a caspase-3 activity test as measures of cell viability in PC12 cells damaged by 6-hydroxydopamine (6-OHDA). The protective effects of PRE against 1-methyl-4-phenylpyridium (MPP(+))-induced neurotoxicity were assessed in rat primary dopaminergic neurons and in a mouse PD model in which PRE was administered (100mg/kg/day, 3 days, p.o.) before acute 1-mehtyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) toxicity. Finally, TH immunohistochemistry tests were conducted in the substantia nigra pars compacta (SNpc) and striatum (ST).

RESULTS AND CONCLUSIONS

PRE significantly inhibited 6-OHDA-induced cell damage at doses of 0.05-1μg/ml with a maximal effect at 0.1μg/ml. Caspase-3 activity and the production of ROS and NO were alleviated at 0.1μg/ml. Also at this dose, PRE protected mesencephalic dopaminergic neurons from MPP(+)-induced toxicity. In an in vivo mouse model of PD, PRE protected dopaminergic neurons and fibers from MPTP-induced toxicity in the SNpc and ST. These results demonstrate that PRE has protective effects on dopaminergic neurons via its anti-oxidant and anti-apoptotic activity.

Cognitive-enhancing effects of polygalasaponin hydrolysate in aβ(25-35)-induced amnesic mice

Polygalasaponins are the major active constituents of Polygala tenuifolia exhibiting antiamnesic activity, but their applications are limited due to their toxicities. Evidence showed that the toxicities can be attenuated by hydrolysis. Herein, effects of a hydrolysate of polygalasaponins (HPS) on cognitive impairment induced by Aβ₂₅₋₃₅ were assessed by Morris water maze and step-through passive avoidance tests. The impaired spatial reference memory was improved by HPS (50 and 100 mg/kg). In the acquisition trial of step-through test, HPS (50 and 100 mg/kg) increased the latency into the dark chamber and decreased the error frequency significantly (P < .05). However, no significant change was observed during the retention trial. Additionally, HPS increased the corresponding SOD activities (62.34%, 22.09%) and decreased MDA levels (28.21%, 32.35%) in both cortex and hippocampus as compared to model animals. These results show that HPS may be a useful treatment against amnesia probably via its antioxidant properties.

Tenuigenin protects cultured hippocampal neurons against methylglyoxal-induced neurotoxicity

Methylglyoxal is a metabolite of glucose. Since serum methylglyoxal level is increased in diabetic patients, methylglyoxal is implicated in diabetic complications such as cognitive impairment. This study aimed to evaluate the effects of tenuigenin, an active component of roots of Polygala tenuifolia Willdenow, on methylglyoxal-induced cell injury in a primary culture of rat hippocampal neurons. MTT and Hoechst 33342 staining, together with flow cytometric analysis using annexin-V and propidium (PI) label, indicated that tenuigenin pretreatment attenuated methylglyoxal -induced apoptotic cell death in primary cultured hippocampal neurons, showing a dose-dependent pattern. Furthermore, 2, 7-dichlorodihydrofluorescein diacetate was used to detect the level of intracellular reactive oxygen species. Tenuigenin decreased the elevated reactive oxygen species induced by methylglyoxal. In addition, tenuigenin inhibited activation of caspase-3 and reversed down-regulation of the ratio of Bcl-2/Bax, both of which were induced by methylglyoxal stimulation. The results suggest that tenuigenin displays antiapoptotic and antioxidative activity in hippocampal neurons due to scavenging of intracellular reactive oxygen species, regulating Bcl-2 family and suppressing caspase-3 activity induced by methylglyoxal, which might explain at least in part the beneficial effects of tenuigenin against degenerative disorders involving diabetic cognitive impairment.