Hexane extract from Polygonum multiflorum attenuates glutamate-induced apoptosis in primary cultured cortical neurons

Kaempferol as a potential neuroprotector in Alzheimer's disease

Alzheimer's disease (AD), the most prevalent neurodegenerative disorder, is largely associated with cognitive disability, amnesia, and abnormal behavior, which accounts for about two third of people with dementia worldwide. A growing body of research demonstrates that AD is connected to several factors, such as aberrant accumulation of amyloid-beta (Aβ), increase in the hyperphosphorylation of Tau protein, and the formation of neurofibrillary tangles, mitochondrial dysfunction, and inordinate production of reactive oxygen species (ROS). Despite remarkable efforts to realize the etiology and pathophysiology of AD, until now, scientists have not developed and introduced medications that can permanently cease the progression of AD. Thus, nowadays, research on the role of natural products in the treatment and prevention of AD has attracted great attention. Kaempferol (KMP), one of the prominent members of flavonols, exerts its ameliorative actions via attenuating oxidative stress and inflammation, reducing Aβ-induced neurotoxicity, and regulating the cholinergic system. Therefore, in this review article, we outlined the possible effects of KMP in the prevention and treatment of AD. PRACTICAL APPLICATIONS: Kaempferol (KMP) exerts its ameliorative actions against AD via attenuating oxidative stress and inflammation, reducing Aβ-induced neurotoxicity, and regulating the cholinergic system. The beneficial effects of KMP were addressed in both in vitro and in vivo studies; however, conducting further research can warrant its long-term effects as a safe agent. Therefore, after confirming its favorable functions in the prevention and treatment of AD, it could be used as a safe and effective agent.

A comprehensive review of traditional uses, phytochemistry and pharmacology of Reynoutria genus

Objectives

The genus Reynoutria belonging to the family Polygonaceae is widely distributed in the north temperate zone and used in folk medicine. It is administered as a sedative, tonic and digestive, also as a treatment for canities and alopecia. Herein, we reported a review on traditional uses, phytochemistry and pharmacology reported from 1985 up to early 2022. All the information and studies concerning Reynoutria plants were summarized from the library and digital databases (e.g. ScienceDirect, SciFinder, Medline PubMed, Google Scholar, and CNKI).

Key findings

A total of 185 articles on the genus Reynoutria have been collected. The phytochemical investigations of Reynoutria species revealed the presence of more than 277 chemical components, including stilbenoids, quinones, flavonoids, phenylpropanoids, phospholipids, lactones, phenolics and phenolic acids. Moreover, the compounds isolated from the genus Reynoutria possess a wide spectrum of pharmacology such as anti-atherosclerosis, anti-inflammatory, antioxidative, anticancer, neuroprotective, anti-virus and heart protection.

Summary

In this paper, the traditional uses, phytochemistry and pharmacology of genus Reynoutria were reviewed. As a source of traditional folk medicine, the Reynoutria genus have high medicinal value and they are widely used in medicine. Therefore, we hope our review can help genus Reynoutria get better development and utilization.

2,3,5,4′-Tetrahydroxystilbene-2-O-β-glucoside Attenuates Reactive Oxygen Species-Dependent Inflammation and Apoptosis in Porphyromonas gingivalis-Infected Brain Endothelial Cells

We recently reported that the periodontopathic bacteria Porphyromonas gingivalis (P. gingivalis) initiates an inflammatory cascade that disrupts the balance of reactive oxygen species (ROS), resulting in apoptotic cell death in brain endothelial cells. An extract from Polygonum multiflorum Thunb., 2,3,5,4′-Tetrahydroxystilbene-2-O-β-glucoside (THSG) has been well-reported to diminish the inflammation in many disease models. However, the effects of THSG in the area of the brain–oral axis is unknown. In this study, we examined the effects of THSG in P. gingivalis-stimulated inflammatory response and apoptotic cell death in brain endothelial cells. THSG treatment remarkably lessened the upregulation of IL-1β and TNF-α proteins in bEnd.3 cells infected with P. gingivalis. Treatment of THSG further ameliorated brain endothelial cell death, including apoptosis caused by P. gingivalis. Moreover, the present study showed that the inhibitory effects on NF-κB p65 and antiapoptotic properties of THSG is through inhibiting the ROS pathway. Importantly, the ROS inhibitory potency of THSG is similar to a ROS scavenger N-Acetyl-L-Cysteine (NAC) and NADPH oxidase inhibitor apocynin. Furthermore, the protective effect of THSG from P. gingivalis infection was further confirmed in primary mouse brain endothelial cells. Taken together, this study indicates that THSG attenuates an ROS-dependent inflammatory response and cell apoptosis in P. gingivalis-infected brain endothelial cells. Our results also suggest that THSG could be a potential herbal medicine to prevent the risk of developing cerebrovascular diseases from infection of periodontal bacteria.

Scalp Acupuncture and Treadmill Training Inhibits Neuronal Apoptosis through Activating cIAP1 in Cerebral Ischemia Rats

Stroke is the leading cause of long-term disability in developed countries. Multitudinous evidence suggests that treadmill training treatment is beneficial for balance and stroke rehabilitation; however, the need for stroke therapy remains unmet. In the present study, a cerebral ischemia rat model was established by permanent middle cerebral artery occlusion (pMCAO) to explore the therapeutic effect and mechanism of scalp acupuncture combined with treadmill training on ischemic stroke. Terminal deoxynucleotidyl transferase-mediated dUTP nick-end labeling and neuronal nuclear protein (NeuN) double staining and cellular inhibitor of apoptosis protein-1 (cIAP1) and NeuN immunofluorescence double staining were used to detect the short-term and long-term neuroprotective effects of scalp acupuncture combined with treadmill training on pMCAO rats. In addition, the antiapoptotic effect of the combined treatment was evaluated in pMCAO rats transfected with cIAP1 shRNA. Western blotting was used to detect the relative protein expression in the caspase-8/-9/-3 activation pathway downstream of cIAP1 to further clarify its regulatory mechanism. Our results showed that scalp acupuncture combined with treadmill training successfully achieved short-term and long-term functional improvement within 14 days after stroke, significantly inhibited neuronal apoptosis, and upregulated the expression of cIAP1 protein in the ischemic penumbra area of the ischemic brain. However, no significant functional improvement and antiapoptotic effect were found in pMCAO rats transfected with cIAP1 shRNA. Western blotting results showed that the combined therapy markedly inhibited the activation of the caspase-8/-9/-3 pathway. These findings indicate that scalp acupuncture combined with treadmill training therapy may serve as a more effective alternative modality in the treatment of ischemic stroke, playing an antiapoptotic role by upregulating the expression of cIAP1 and inhibiting the activation of the caspase-8/-9/-3 pathway.

Recent progress regarding kaempferol for the treatment of various diseases

Kaempferol, also known as kaempferol-3 or kaempferide, is a flavonoid compound that naturally occurs in tea, as well as numerous common vegetables and fruits, including beans, broccoli, cabbage, gooseberries, grapes, kale, strawberries, tomatoes, citrus fruits, brussel sprouts, apples and grapefruit. The present review mainly summarizes the application of kaempferol in treating diseases and the underlying mechanisms that are currently being studied. Due to its anti-inflammatory properties, it may be used to treat numerous acute and chronic inflammation-induced diseases, including intervertebral disc degeneration and colitis, as well as post-menopausal bone loss and acute lung injury. In addition, it has beneficial effects against cancer, liver injury, obesity and diabetes, inhibits vascular endothelial inflammation, protects the cranial nerve and heart function, and may be used for treating fibroproliferative disorders, including hypertrophic scar.

DR-region of Na+/K+ ATPase is a target to treat excitotoxicity and stroke

Na⁺/K⁺ ATPase (NKA) is important in maintaining cellular functions. We found that loss of NKA activities in NKAα1^+/− mice is associated with increased susceptibility to ischemic injuries following transient middle cerebral artery occlusion (tMCAO). This is corroborated by the neuroprotective effects of an antibody raised against an extracellular DR region (⁸⁹⁷DVEDSYGQQWTYEQR⁹¹¹, sequence number as in rat) of NKAα subunit (DR-Ab) in both preventive and therapeutic settings. DR-Ab protects cortical neurons against glutamate-induced toxicity by stimulating activities of NKA and Na⁺/Ca²⁺ exchanger (NCX), which resulted in accelerated Ca²⁺ extrusion. DR-Ab also enhanced the association between NKA and GluR2 and therefore reduced the internalization of both proteins from membrane induced by glutamate toxicity. The mechanism appears to involve suppression of GluR2 phosphorylation through PKCα/PICK pathway. Our data indicate that DR-region of NKA may be a novel therapeutic target for drug development for the treatment of ischemic stroke.

Polygonum multiflorum Extract Exerts Antioxidative Effects and Increases Life Span and Stress Resistance in the Model Organism Caenorhabditis elegans via DAF-16 and SIR-2.1

Extracts of the Chinese plant Polygonum multiflorum (PME) are used for medicinal purposes as well as food supplement due to anti-aging effects. Despite of the common use of these food supplements, experimental data on physiological effects of PME and its underlying molecular mechanisms in vivo are limited. We used the model organism Caenorhabditis elegans to analyze anti-aging-effects of PME in vivo (life span, lipofuscin accumulation, oxidative stress resistance, thermal stress resistance) as well as the molecular signaling pathways involved. The effects of PME were examined in wildtype animals and mutants defective in the sirtuin-homologue SIR-2.1 (VC199) and the FOXO-homologue DAF-16 (CF1038). PME possesses antioxidative effects in vivo and increases oxidative stress resistance of the nematodes. While the accumulation of lipofuscin is only slightly decreased, PME causes a significant elongation (18.6%) of mean life span. DAF-16 is essential for the reduction of thermally induced ROS accumulation, while the resistance against paraquat-induced oxidative stress is dependent on SIR-2.1. For the extension of the life span, both DAF-16 and SIR-2.1 are needed. We demonstrate that PME exerts protective effects in C. elegans via modulation of distinct intracellular pathways.

Natural products against Alzheimer's disease: Pharmaco-therapeutics and biotechnological interventions

Alzheimer's disease (AD) is a severe, chronic and progressive neurodegenerative disease associated with memory and cognition impairment ultimately leading to death. It is the commonest reason of dementia in elderly populations mostly affecting beyond the age of 65. The pathogenesis is indicated by accumulation of the amyloid-beta (Aβ) plaques and neurofibrillary tangles (NFT) in brain tissues and hyperphosphorylation of tau protein in neurons. The main cause is considered to be the formation of reactive oxygen species (ROS) due to oxidative stress. The current treatment provides only symptomatic relief by offering temporary palliative therapy which declines the rate of cognitive impairment associated with AD. Inhibition of the enzyme acetylcholinesterase (AChE) is considered as one of the major therapeutic strategies offering only symptomatic relief and moderate disease-modifying effect. Other non-cholinergic therapeutic approaches include antioxidant and vitamin therapy, stem cell therapy, hormonal therapy, use of antihypertensive or lipid-lowering medications and selective phosphodiesterase (PDE) inhibitors, inhibition of β-secretase and γ-secretase and Aβ aggregation, inhibition of tau hyperphosphorylation and intracellular NFT, use of nonsteroidal anti-inflammatory drugs (NSAIDs), transition metal chelators, insulin resistance drugs, etanercept, brain-derived neurotrophic factor (BDNF) etc. Medicinal plants have been reported for possible anti-AD activity in a number of preclinical and clinical trials. Ethnobotany, being popular in China and in the Far East and possibly less emphasized in Europe, plays a substantial role in the discovery of anti-AD agents from botanicals. Chinese Material Medica (CMM) involving Chinese medicinal plants has been used traditionally in China in the treatment of AD. Ayurveda has already provided numerous lead compounds in drug discovery and many of these are also undergoing clinical investigations. A number of medicinal plants either in their crude forms or as isolated compounds have exhibited to reduce the pathological features associated with AD. In this present review, an attempt has been made to elucidate the molecular mode of action of various plant extracts, phytochemicals and traditional herbal formulations investigated against AD as reported in various preclinical and clinical tests. Herbal synergism often found in polyherbal formulations were found effective to combat disease heterogeneity as found in complex pathogenesis of AD. Finally a note has been added to describe biotechnological improvement, genetic and genomic resources and mathematical and statistical techniques for empirical model building associated with anti-AD plant secondary metabolites and their source botanicals.

Urine metabolomics study on the liver injury in rats induced by raw and processed Polygonum multiflorum integrated with pattern recognition and pathways analysis

ETHNOPHARMACOLOGICAL RELEVANCE

Polygonum multiflorum L. is a famous traditional Chinese medicine that has always been perceived to be safe. Recently, the increasing case reports on hepatotoxicity induced by Raw P. multiflorum (RP) have attracted particular attention. However, the diagnosis and identification of RP-induced hepatotoxicity are still very difficult for its unknown mechanism and the lack of specific biomarkers.

AIM OF THE STUDY

To further explore the toxicity and metabolic mechanisms involved in the hepatotoxicity induced by RP.

MATERIALS AND METHODS

The hepatotoxicity induced by RP and its processed products (PP) (dosed at 20g/kg for 4 weeks) on rats were investigated using conventional approaches including the biochemical analysis and histopathological observations. Further, a urinary metabolomic approach was developed to study the metabolic disturbances caused by RP and PP, followed by the pattern recognition approach and pathways analysis.

RESULTS

RP showed obvious hepatotoxity whereas PP did not. 16 potential biomarkers (pyridoxamine, 4-pyridoxic acid, citrate et al.) differentially expressed in RP group were identified compared with the control and PP-treated groups. The pathways analysis showed that vitamin B6 metabolism, tryptophan metabolism and citrate cycle might be the major enriched pathways involved in the hepatotoxicity of the herb.

CONCLUSION

16 differentially expressed metabolites were identified to be involved in the RP-induced hepatotoxicity. Vitamin B6 metabolism might be mostly related to the hepatotoxicity induced by RP. This finding may provide a potential therapeutic target or option to treat hepatotoxicity induced by RP.

Emodin from Polygonum multiflorum ameliorates oxidative toxicity in HT22 cells and deficits in photothrombotic ischemia

ETHNOPHARMACOLOGICAL RELEVANCE

Polygonum multiflorum Thunb. has been used widely in East Asia in treatment of diseases associated with aging. Emodin, an active component from Polygonum multiflorum Thunb., provides benefits for brain disturbances induced by severe cerebral injury.

AIM OF THE STUDY

We investigated the neuroprotective effect of emodin from Polygonum multiflorum Thunb. against glutamate-induced oxidative toxicity and cerebral ischemia.

MATERIALS AND METHODS

For examination of neuroprotective effects of emodin, cell viability, cytotoxicity, flow cytometry, and Western blot were performed in HT22 cells and infarct volume, behavioral tests and Western blot in a mouse model of photothrombotic ischemic stroke.

RESULTS

Pretreatment with emodin resulted in significantly reduced glutamate-induced apoptotic cell death in HT22 cells. However, blocking of phosphatidylinositol-3 kinase (PI3K) activity with LY294002 resulted in significantly inhibited cell survival by emodin. Exposure of glutamate-treated cells to emodin induced an increase in the level of Bcl-2 expression, whereas the expression of Bax and active caspase-3 proteins was significantly reduced. In addition, treatment with emodin resulted in increased phosphorylation of Akt and cAMP response element binding protein (CREB), and expression of mature brain-derived neurotrophic factor (BDNF). This expression by emodin was also significantly inhibited by blocking of PI3K activity. In a photothrombotic ischemic stroke model, treatment with emodin resulted in significantly reduced infarct volume and improved motor function. We confirmed the critical role of the expression levels of Bcl-2/Bax, active caspase-3, phosphorylated (p)Akt, p-CREB, and mature BDNF for potent neuroprotective effects of emodin in cerebral ischemia.

CONCLUSIONS

These results suggest that emodin may afford a significant neuroprotective effect against glutamate-induced apoptosis through activation of the PI3K/Akt signaling pathway, and subsequently enhance behavioral function in cerebral ischemia.

Huannao Yicong Decoction () extract reduces inflammation and cell apoptosis in Aβ1-42-induced Alzheimer's disease model of rats

OBJECTIVE

Huannao Yicong Decoction (, HYD), an effective herbal formula against Alzheimer's disease (AD), has been proven to have neuroprotective action in amyloid β-protein_1-42 (Aβ_1-42)-induced rat model. This study was designed to characterize mechanisms by which HYD leads to suppression of inflflammation and apoptosis in the brains of Aβ_1-42-induced rat.

METHODS

A total of 72 rats were divided into 6 groups, which were referred to as: sham operation group, model group, donepezil-treated group, HYD low-dose group (HYDL), HYD middle-dose group (HYDM) and HYD high-dose group (HYDH). Rats in HYDL, HYDM and HYDH were injected with Aβ_1-42 at the CA1 region of hippocampus to form AD model and were fed the HYD extract at different dose of 3.78, 7.56 and 18.90 g crude drug/kg. The behavioral changes of rats were evaluated by Morris water maze (MWM) before sacrififice. Pathological changes of the brain tissue were evaluated using hematoxylin eosin (HE) staining. The levels of interleukin-1 (IL-1) and tumor necrosis factor-α (TNF-α) were measured by radioimmunoassay. The levels of Aβ and proteins that are associated with apoptosis such as B-cell lymphoma-2 protein (Bcl-2), Bcl-2-associated X protein (Bax), cysteine-aspartic protease (caspase)-3, -8, -9 and -12 in serum were measured by immunohistochemistry.

RESULTS

Compared with the sham operation group, the spatial learning and memory abilities of AD rats were signifificantly decreased (P<0.05 or P<0.01; Expressions of IL-1, TNF-α, Aβ and apoptosis-signaling proteins caspase-3, -8, -9, -12 were signifificantly up-regulated (P<0.05 or P<0.01). The ratio of Bcl-2 to Bax were signifificantly decreased in the model group (P<0.01). When treated with HYD extract, the spatial learning and memory abilities of AD-model rats were significantly increased (P<0.05 or P<0.01), IL-1, TNF-α, Aβ, caspase-3, -8, -9 and -12 were down-regulated (P<0.05 or P<0.01), and the ratio of Bcl-2 to Bax were reduced (P<0.05 or P<0.01).

CONCLUSIONS

HYD extract can improve the learning and memory ability defificits, alleviate the inflflammatory response and pathological manifestations induced by Aβ_1-42 injection in the rat model of AD. HYD down-regulates the levels of IL-1, TNF-α and Aβ, and decreases the rate of apoptosis by modulating apoptosis-signaling-related proteins such as caspase-3, -8, -9, and -12.

Beneficial Effects of Polygonum multiflorum on Hippocampal Neuronal Cells and Mouse Focal Cerebral Ischemia

Beneficial effects of the water extract of Polygonum multiflorum (WEPM) and their mechanisms were investigated in HT22 hippocampal cells and hippocampus of middle cerebral artery occlusion (MCAO) mice. In HT22 cells against glutamate-induced oxidative stress, pretreatment with WEPM resulted in significantly reduced apoptotic neuronal death. Pretreatment with WEPM resulted in the suppression of ROS accumulation in connection with cellular Ca 2+ level after exposure to glutamate. Treatment with glutamate alone led to suppressed protein level of mature brain-derived neurotrophic factor (BDNF) and phosphorylated cAMP response element binding protein (CREB); however, pretreatment with either WEPM or anti-oxidant N-acetyl-ʟ-cysteine (NAC) resulted in the significant enhancement of levels of these proteins. In addition, levels of mature BDNF expression and CREB phosphorylation were increased by combined treatment with WEPM, NAC, and intracellular Ca 2+ inhibitor BAPTA compared to other treatment groups. In MCAO mice, we confirmed the critical role of mature BDNF expression and CREB phosphorylation by WEPM in the neurons of the hippocampus. Our results suggest that WEPM mainly exerted beneficial effects on hippocampal neurons through the suppression of ROS accumulation and up-regulation of mature BDNF expression and CREB phosphorylation.

Neuroprotection and spatial memory enhancement of four herbal mixture extract in HT22 hippocampal cells and a mouse model of focal cerebral ischemia

BACKGROUND

Four traditional Korean medicinal herbs which act in retarding the aging process, Polygonum multiflorum Thunb., Rehmannia glutinosa (Gaertn) Libosch., Polygala tenuifolia Willd., and Acorus gramineus Soland., were prepared by systematic investigation of Dongeuibogam (Treasured Mirror of Eastern Medicine), published in the early 17th century in Korea. This study was performed to evaluate beneficial effects of four herbal mixture extract (PMC-12) on hippocampal neuron and spatial memory.

METHODS

High performance liquid chromatography (HPLC) analysis was performed for standardization of PMC-12. Cell viability, lactate dehydrogenase, flow cytometry, reactive oxygen species (ROS), and Western blot assays were performed in HT22 hippocampal cells and immunohistochemistry and behavioral tests were performed in a mouse model of focal cerebral ischemia in order to observe alterations of hippocampal cell survival and subsequent memory function.

RESULTS

In the HPLC analysis, PMC-12 was standardized to contain 3.09% 2,3,5,4'-tetrahydroxystilbene-2-O-β-D-glucoside, 0.35% 3',6-disinapoyl sucrose, and 0.79% catalpol. In HT22 cells, pretreatment with PMC-12 resulted in significantly reduced glutamate-induced apoptotic cell death. Pretreatment with PMC-12 also resulted in suppression of ROS accumulation in connection with cellular Ca(2+) level after exposure to glutamate. Expression levels of phosphorylated p38 mitogen-activated protein kinases (MAPK) and dephosphorylated phosphatidylinositol-3 kinase (PI3K) by glutamate exposure were recovered by pretreatment with either PMC-12 or anti-oxidant N-acetyl-L-cysteine (NAC). Expression levels of mature brain-derived neurotrophic factor (BDNF) and phosphorylated cAMP response element binding protein (CREB) were significantly enhanced by treatment with either PMC-12 or NAC. Combination treatment with PMC-12, NAC, and intracellular Ca(2+) inhibitor BAPTA showed similar expression levels. In a mouse model of focal cerebral ischemia, we observed higher expression of mature BDNF and phosphorylation of CREB in the hippocampus and further confirmed improved spatial memory by treatment with PMC-12.

CONCLUSIONS

Our results suggest that PMC-12 mainly exerted protective effects on hippocampal neurons through suppression of Ca(2+)-related ROS accumulation and regulation of signaling pathways of p38 MAPK and PI3K associated with mature BDNF expression and CREB phosphorylation and subsequently enhanced spatial memory.

TSG (2,3,5,4'-Tetrahydroxystilbene-2-O- β -D-glucoside) from the Chinese Herb Polygonum multiflorum Increases Life Span and Stress Resistance of Caenorhabditis elegans

2,3,5,4'-Tetrahydroxystilbene-2-O-β-D-glucoside (TSG) was isolated from Polygonum multiflorum, a plant which is traditionally used as an anti-ageing drug. We have analysed ageing-related effects of TSG in the model organism C. elegans in comparison to resveratrol. TSG exerted a high antioxidative capacity both in a cell-free assay and in the nematode. The antioxidative capacity was even higher compared to resveratrol. Presumably due to its antioxidative effects, treatment with TSG decreased the juglone-mediated induction of the antioxidative enzyme SOD-3; the induction of the GST-4 by juglone was diminished slightly. TSG increased the resistance of C. elegans against lethal thermal stress more prominently than resveratrol (50 μM TSG increased mean survival by 22.2%). The level of the ageing pigment lipofuscin was decreased after incubation with the compound. TSG prolongs the mean, median, and maximum adult life span of C. elegans by 23.5%, 29.4%, and 7.2%, respectively, comparable to the effects of resveratrol. TSG-mediated extension of life span was not abolished in a DAF-16 loss-of-function mutant strain showing that this ageing-related transcription factor is not involved in the effects of TSG. Our data show that TSG possesses a potent antioxidative capacity, enhances the stress resistance, and increases the life span of the nematode C. elegans.

PMC-12, a Prescription of Traditional Korean Medicine, Improves Amyloid β-Induced Cognitive Deficits through Modulation of Neuroinflammation

PMC-12 is a prescription used in traditional Korean medicine that consists of a mixture of four herbal medicines, Polygonum multiflorum, Rehmannia glutinosa, Polygala tenuifolia, and Acorus gramineus, which have been reported to have various pharmacological effects on age-related neurological diseases. In the present study, we investigated whether PMC-12 improves cognitive deficits associated with decreased neuroinflammation in an amyloid-β-(Aβ-) induced mouse model and exerts the antineuroinflammatory effects in lipopolysaccharide-(LPS-) stimulated murine BV2 microglia. Intracerebroventricular injection of Aβ₂₅₋₃₅ in mice resulted in impairment in learning and spatial memory, whereas this was reversed by oral administration of PMC-12 (100 and 500 mg/kg/day) in dose-dependent manners. Moreover, PMC-12 reduced the increase of Aβ expression and activation of microglia and astrocytes in the Aβ₂₅₋₃₅-injected brain. Furthermore, quantitative PCR data showed that inflammatory mediators were significantly decreased by administration of PMC-12 in Aβ-injected brains. Consistent with the in vivo data, PMC-12 significantly reduced the inflammatory mediators in LPS-stimulated BV2 cells without cell toxicity. Moreover, PMC-12 exhibited anti-inflammatory properties via downregulation of ERK, JNK, and p38 MAPK pathways. These findings suggest that the protective effects of PMC-12 may be mediated by its antineuroinflammatory activities, resulting in the attenuation of memory impairment; accordingly, PMC-12 may be useful in the prevention and treatment of AD.

Establishment of a comprehensive list of candidate antiaging medicinal herb used in korean medicine by text mining of the classical korean medical literature, "dongeuibogam," and preliminary evaluation of the antiaging effects of these herbs

The major objectives of this study were to provide a list of candidate antiaging medicinal herbs that have been widely utilized in Korean medicine and to organize preliminary data for the benefit of experimental and clinical researchers to develop new drug therapies by analyzing previous studies. "Dongeuibogam," a representative source of the Korean medicine literature, was selected to investigate candidate antiaging medicinal herbs and to identify appropriate terms that describe the specific antiaging effects that these herbs are predicted to elicit. In addition, we aimed to review previous studies that referenced the selected candidate antiaging medicinal herbs. From our chosen source, "Dongeuibogam," we were able to screen 102 terms describing antiaging effects, which were further classified into 11 subtypes. Ninety-seven candidate antiaging medicinal herbs were selected using the criterion that their antiaging effects were described using the same terms as those employed in "Dongeuibogam." These candidates were classified into 11 subtypes. Of the 97 candidate antiaging medicinal herbs selected, 47 are widely used by Korean medical doctors in Korea and were selected for further analysis of their antiaging effects. Overall, we found an average of 7.7 previous studies per candidate herb that described their antiaging effects.

Traditional usages, botany, phytochemistry, pharmacology and toxicology of Polygonum multiflorum Thunb.: a review

ETHNOPHARMACOLOGICAL RELEVANCE

Polygonum multiflorum Thunb., which is known as Heshouwu ( in Chinese) in China. It is traditionally valued and reported for hair-blacking, liver and kidney-tonifying and anti-aging effects as well as low toxicity. The aim of this review is to provide comprehensive information on the botany, traditional uses, phytochemistry, pharmacological research and toxicology of Polygonum multiflorum, based on the scientific literature. Moreover, trends and perspectives for future investigation of this plant are discussed. It will build up a new foundation for further study on Polygonum multiflorum.

MATERIALS AND METHODS

A systematic review of the literature on Polygonum multiflorum was performed using several resources, including classic books on Chinese herbal medicine and various scientific databases, such as PubMed, SciFinder, the Web of Science, Science Direct, China Knowledge Resource Integrated (CNKI).

RESULTS

Polygonum multiflorum is widely distributed throughout the world and has been used as a traditional medicine for centuries in China. The ethnomedical uses of Polygonum multiflorum have been recorded in many provinces of China and Japan for nine species of adulterants in six families. More than 100 chemical compounds have been isolated from this plant, and the major components have been determined to be stilbenes, quinones, flavonoids and others. Crude extracts and pure compounds of this plant are used as effective agents in pre-clinical and clinical practice due to their anti-aging, anti-hyperlipidaemia, anti-cancer and anti-inflammatory effects and to promote immunomodulation, neuroprotection, and the curing of other diseases. However, these extracts can also lead to hepatotoxicity, nephrotoxicity and embryonic toxicity. Pharmacokinetic studies have demonstrated that the main components of Polygonum multiflorum, such as 2,3,5,4'-tetrahydroxystilbene-2-O-β-d-glucopyranoside and emodin are distributed among many organs and tissues.

CONCLUSION

Therapeutic potential of Polygonum multiflorum has been demonstrated in the conditions like Alzheimer׳s disease, Parkinson׳s disease, hyperlipidaemia, inflammation and cancer, which is attributed to the presence of various stilbenes, quinones, flavonoids, phospholipids and other compounds in the drug. On the other hand, the adverse effects (hepatotoxicity, nephrotoxicity, and embryonic toxicity) of this plant were caused by the quinones, such as emodin and rhein. Thus more pharmacological and toxicological mechanisms on main active compounds are necessary to be explored, especially the combined anthraquinones (Emodin-8-O-β-d-glucopyranoside, Physcion-8-O-β-d-glucopyranoside, etc.) and the variety of stilbenes.

The Protective Effect of Radix Polygoni Multiflori on Diabetic Encephalopathy via Regulating Myosin Light Chain Kinase Expression

Currently there has been no effective treatment of diabetic encephalopathy. Radix Polygoni Multiflori, a famous traditional Chinese medicine, is widely used in antiaging treatment, especially in prevention and treatment of Alzheimer's diseases. In this study we tried to explore the effect of Radix Polygoni Multiflori on cognitive function among diabetic rats with demonstrated cognitive impairment. SD rats were divided into group A (control group), group B (diabetes), group C (treated with Radix Polygoni Multiflori at the dose of 2 g/kg/d), and group D (treated with same drug at the dose of 1 g/kg/d). The results showed that 8 weeks of Radix Polygoni Multiflori treatment could improve the cognitive dysfunction of diabetic rats (P < 0.01), recover the ultrastructure of hippocampal neurons, and increase the number of synapses in a dose-dependent manner. Further experiment also suggested that the neuroprotective effect of Radix Polygoni Multiflori was partly achieved by downregulating MLCK expression in hippocampus via ERK signaling.

ERKs and mitochondria-related pathways are essential for glycyrrhizic acid-mediated neuroprotection against glutamate-induced toxicity in differentiated PC12 cells

The present study focuses on the neuroprotective effect of glycyrrhizic acid (GA, a major compound separated from Glycyrrhiza Radix, which is a crude Chinese traditional drug) against glutamate-induced cytotoxicity in differentiated PC12 (DPC12) cells. The results showed that GA treatment improved cell viability and ameliorated abnormal glutamate-induced alterations in mitochondria in DPC12 cells. GA reversed glutamate-suppressed B-cell lymphoma 2 levels, inhibited glutamate-enhanced expressions of Bax and cleaved caspase 3, and reduced cytochrome C (Cyto C) release. Exposure to glutamate strongly inhibited phosphorylation of AKT (protein kinase B) and extracellular signal-regulated kinases (ERKs); however, GA pretreatment enhanced activation of ERKs but not AKT. The presence of PD98059 (a mitogen-activated protein/extracellular signal-regulated kinase kinase [MEK] inhibitor) but not LY294002 (a phosphoinositide 3-kinase [PI3K] inhibitor) diminished the potency of GA for improving viability of glutamate-exposed DPC12 cells. These results indicated that ERKs and mitochondria-related pathways are essential for the neuroprotective effect of GA against glutamate-induced toxicity in DPC12 cells. The present study provides experimental evidence supporting GA as a potential therapeutic agent for use in the treatment of neurodegenerative diseases.

Kaempferol attenuates the glutamate-induced oxidative stress in mouse-derived hippocampal neuronal HT22 cells

It is thought that the neuronal cell loss caused by oxidative stress is the primary mechanism underlying the pathogenesis of several neurodegenerative disorders. Glutamate is an endogenous neurotransmitter, but at high concentrations it can act as a neurotoxicant by increasing the intracellular levels of reactive oxygen species (ROS). Therefore, the development of factors that can attenuate glutamate-induced oxidative stress in neuronal cells is a good strategy by which new drugs could be discovered that may treat or prevent neurodegenerative diseases. Here, the neuroprotective effects of kaempferol (KF) isolated from the stems of butterbur (Petasites japonicus) were examined in glutamate-treated hippocampal neuronal cells (HT22). The administration of KF (25 μM) resulted in a significant increase in cell viability (105.18 ± 7.48%) compared with the control (100.00 ± 3.05%), while glutamate (5 mM) reduced cell viability by 39.94 ± 1.61%. The glutamate-induced calcium (Ca(2+)) influx (1.93 ± 0.08-fold) was significantly reduced by 0.89 ± 0.02-fold following the administration of 25 μM KF. Additionally, when HT22 cells were stressed with excessive glutamate, there was a 3.70 ± 0.01-fold increase in intracellular ROS generation, even though this was effectively attenuated by KF (25 μM, 0.72 ± 0.01-fold). The protective effects of KF in HT22 cells were later confirmed using a lactate dehydrogenase (LDH) assay and a FITC-annexin V/propidium iodide double staining procedure. These findings also revealed that the neuroprotective effects of KF are a result of the regulation of the expression levels of proteins, such as Bcl-2, Bid, apoptosis-inducing factor (AIF), and mitogen-activated protein kinase (MAPK). This is the first report to investigate the neuroprotective influence of KF in glutamate-treated HT22 cells. These data demonstrate that KF may be a useful candidate for pharmacological therapies that can prevent and treat neurodegenerative diseases such as Alzheimer's disease (AD).

Transcriptome profiling and digital gene expression analysis of Fallopia multiflora to discover putative genes involved in the biosynthesis of 2,3,5,4'-tetrahydroxy stilbene-2-O-β-D-glucoside

The compound 2,3,5,4'-tetrahydroxy stilbene-2-O-ß-d-glucoside (THSG) synthesized by Fallopia multiflora (F. multiflora) exhibits pharmacological potency. However, the mechanistic details of its biosynthesis pathway are still vague. To clear this ambiguity, we performed de novo transcriptome assembly and digital gene expression (DGE) profiling analyses of F. multiflora using the Illumina RNA-seq system. RNA-seq generated approximately 70 million high-quality reads that were assembled into 65,653 unigenes (mean length=750 bp), including 26,670 clusters and 38,983 singletons. A total of 48,173 (73.4%) unigenes were annotated using public protein databases with a cut-off e-value above 10(-5). Furthermore, we investigated the transcriptome difference of four different F. multiflora tissues using DGE profiling. Variations in gene expression were identified based on comparisons of transcriptomes from various parts of a high-level THSG- and a low-level THSG-producing F. multiflora plant. Clusters with similar differential expression patterns and enriched metabolic pathways with regard to the differentially expressed genes putatively involved in THSG biosynthesis were revealed for the first time. Our data provides the most comprehensive sequence resource regarding F. multiflora so far. Taken together, the results of this study considerably extend the knowledge on THSG production.

Liquiritin modulates ERK‑ and AKT/GSK‑3β‑dependent pathways to protect against glutamate‑induced cell damage in differentiated PC12 cells

Glutamate has a key role in the neuronal cell damage associated with Alzheimer's and Parkinson's diseases. Liquiritin (LQ), a major constituent of Glycyrrhiza Radix, possesses various pharmacological activities. The present study investigated the neuroprotective effect of LQ against glutamate‑induced cell damage in the differentiated PC12 (DPC12) rat pheochromocytoma cell line. Pretreatment with 25 and 50 µM LQ for 3 h resulted in a significant increase in cell viability and inhibited excessive lactate dehydrogenase release in glutamate‑exposed DPC12 cells. LQ also ameliorated glutamate‑induced nuclear and mitochondrial apoptotic alterations, intracellular calcium overload and the abnormal expression of apoptosis‑related proteins, including cytochrome c, B‑cell lymphoma (Bcl)‑2 and Bcl2‑associated X protein. Treatment with LQ alone or in combination with glutamate was found to enhance the phosphoactivation of extracellular signal‑regulated kinases (ERKs), AKT and its downstream element glycogen synthase kinase‑3β (GSK3β), in a time‑dependent manner. However, no effect was observed on the expression of total‑ERKs, ‑AKT and ‑GSK3β. Furthermore, pre‑incubation with 10 µM PD98059 or LY94002, inhibitors of ERK and phosphatidylinositide 3‑kinase, respectively, for 30 min significantly suppressed the LQ‑induced increase in glutamate‑exposed DPC12 cell viability. To the best of our knowledge, the present study provides the first experimental evidence that LQ has a neuroprotective effect against glutamate toxicity in DPC12 cells, predominantly through the ERK and AKT/GSK‑3β pathways. Therefore, LQ may have potential for the treatment of neurodegenerative diseases.

Hexane extracts of Polygonum multiflorum improve tissue and functional outcome following focal cerebral ischemia in mice

Polygonum multiflorum is a traditional Korean medicine that has been utilized widely in East Asian countries as a longevity agent. Clinical studies have demonstrated that Polygonum multiflorum improves hypercholesterolemia, coronary heart disease, neurosis and other diseases commonly associated with aging. However, scientific evidence defining the protective effects and mechanisms of Polygonum multiflorum against ischemic stroke is incomplete. In the present study, we investigated the cerebrovascular protective effects of Polygonum multiflorum against ischemic brain injury using an in vivo photothrombotic mouse model. To examine the underlying mechanism of action, we utilized an in vitro human brain microvascular endothelial cell (HBMEC) culture system. Hexane extracts (HEPM), ethyl acetate extracts (EAEPM) and methanol extracts (MEPM) of Polygonum multiflorum (100 mg/kg) were administered intraperitoneally 30 min prior to ischemic insult. Focal cerebral ischemia was induced in C57BL/6J mice and endothelial nitric oxide synthase knockout (eNOS KO) mice by photothrombotic cortical occlusion. We evaluated the infarct volume, as well as neurological and motor function, 24 h after ischemic brain injury. Following ischemic insult, HEPM induced a significant reduction in infarct volume and subsequent neurological deficits, compared with EAEPM and MEPM. HEPM significantly decreased infarct size and improved neurological and motor function, which was not observed in eNOS KO mice, suggesting that this cerebroprotective effect is primarily an eNOS-dependent mechanism. In vitro, HEPM effectively promoted NO production, however these effects were inhibited by the NOS inhibitor, L-NAME and the PI3K/Akt inhibitor, LY-294002. Furthermore, HEPM treatment resulted in increased phosphorylation-dependent activation of Akt and eNOS in HBMEC, suggesting that HEPM increased NO production via phosphorylation-dependent activation of Akt and eNOS. In conclusion, HEPM prevents cerebral ischemic damage through an eNOS-dependent mechanism, and thus may have clinical applications as a protective agent against neurological injury in stroke.

Neuroprotective effects of Polygonum multiflorum extract against glutamate-induced oxidative toxicity in HT22 hippocampal cells

ETHNOPHARMACOLOGICAL RELEVANCE

Dried roots of Polygonum multiflorum have traditionally been used in the retarding of aging process in East Asian countries and its extracts exhibit anti-oxidative activities.

MATERIALS AND METHODS

Neuroprotective effects of ethyl acetate extract from Polygonum multiflorum (EEPM) were investigated against glutamate-induced oxidative cell death in HT22 hippocampal cells. Cell viability, cytotoxicity, morphological, flow cytometry, and Western blot assays were performed in order to observe alterations of neuronal cell survival or death related pathways.

RESULTS

Pretreatment with EEPM resulted in significantly decreased glutamate-induced neurotoxicity and also resulted in drastically inhibited glutamate-induced apoptotic and necrotic neuronal death. To elucidate possible pathways of neuroprotection by EEPM, we explored the activation of mitogen activated protein kinases (MAPKs), phosphatidylinositol-3-kinase, and cAMP responsive element binding protein (CREB). Treatment with glutamate alone led to activation of extracellular regulated kinase (ERK), Jun N-terminal kinase, and p38 during the late phase after glutamate exposure, but pretreatment with EEPM resulted in significantly attenuated activation of these proteins. Pretreatment with EEPM resulted in increased activation of CREB. The specific inhibitors of ERK and p38, PD98059 and SB203580, abrogated the neuroprotective effects of EEPM. When we evaluated calpain I and striatal-enriched protein tyrosine phosphatase (STEP), active form of calpain I was significantly increased after glutamate exposure, and, along with this, active form of STEP showed a decrease. Pretreatment with EEPM resulted in significant recovery of pro-calpain I and active form of STEP caused by glutamate. Co-treatment with calpain inhibitor ALLN and EEPM had a synergistic effect on neuronal death and contributed to blockade of activation of both ERK and p38 with increased activation of CREB.

CONCLUSIONS

These results suggest that Polygonum multiflorum extract may have neuroprotective effects through both alleviation of ERK and p38 activation with increased activation of CREB under oxidative stress and has potential as a therapeutic intervention for treatment of oxidative neuronal death.

Neuroprotective effects of paeoniflorin, but not the isomer albiflorin, are associated with the suppression of intracellular calcium and calcium/calmodulin protein kinase II in PC12 cells

The root of Paeonia lactiflora Pall (family Ranunculaceae) or peony root, a herbal medicine, possesses therapeutic potential for neurodegenerative diseases. The isomers paeoniflorin (PF) and albiflorin (AF) are major constituents contained in peony root. Our previous study has shown notable neuroprotective effects of PF. In the present study, we further compared the effects of AF and PF against glutamate (Glu)-induced cell damage and the underlying mechanisms in differentiated PC12 cells. Both AF and PF significantly ameliorated Glu-induced reduction of cell viability, nuclear and mitochondrial apoptotic alteration, reactive oxygen species accumulation, and B-cell lymphoma 2 (Bcl-2)/Bax ratio. The two isomers also enhanced phosphorylation of AKT and its downstream element glycogen synthase kinase-3β, and this effect was abrogated by the AKT inhibitor LY294002. PF, but not AF, however, suppressed intracellular Ca(2+) overload and the expression of calcium/calmodulin protein kinase II (CaMKII). The improvement of cell damage by the CaMKII inhibitor KN93 further confirms the role of CaMKII in PF-mediated neuroprotection. These results suggest that both AF and PF possess robust effects in protecting neuronal cells against Glu toxicity. PF further displayed remarkable effects in preventing intracellular Ca(2+) overload and suppressing overexpression of CaMKII. Differential mechanisms may be involved in neuroprotective action of the two isomers.