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

Preclinical Evidence and Underlying Mechanisms of Polygonum multiflorum and Its Chemical Constituents Against Cognitive Impairments and Alzheimer's Disease

Objectives

Cognitive impairments, ranging from mild to severe, adversely affect daily functioning, quality of life, and work capacity. Despite significant efforts in the past decade, more than 200 promising drug candidates have failed in clinical trials. Herbal remedies are gaining interest as potential treatments for dementia due to their long history and safety, making them valuable for drug development. This review aimed to examine the mechanisms behind the effect of Polygonum multiflorum on cognitive function.

Methods

This study focused primarily on the effects of Polygonum multiflorum and its chemical constituents on cognitive behavioral outcomes including the Morris water maze, the passive avoidance test, and the Y maze, as well as pathogenic targets of cognitive impairment and Alzheimer's disease (AD) like amyloid deposition, amyloid precursor protein, tau hyperphosphorylation, and cognitive decline. Additionally, a thorough evaluation of the mechanisms behind Polygonum multiflorum's impact on cognitive function was conducted. We reviewed the most recent data from preclinical research done on experimental models, particularly looking at Polygonum multiflorum's effects on cognitive decline and AD.

Results

According to recent research, Poligonum multiflorum and its bioactive components, stilbene, and emodin, influence cognitive behavioral results and regulate the pathological target of cognitive impairment and AD. Their mechanisms of action include reducing oxidative and mitochondrial damage, regulating neuroinflammation, halting apoptosis, and promoting increased neurogenesis and synaptogenesis.

Conclusion

This review serves as a comprehensive compilation of current experiments on AD and other cognitive impairment models related to the therapeutic effects of Polygonum multiflorum. We believe that these findings can serve as a basis for future clinical trials and have potential applications in the treatment of human neurological disorders.

Cyclooxygenase-2 Inhibitors as a Therapeutic Target in Inflammatory Diseases

Inflammation plays a crucial role in the development of many complex diseases and disorders including autoimmune diseases, metabolic syndrome, neurodegenerative diseases, and cardiovascular pathologies. Prostaglandins play a regulatory role in inflammation. Cyclooxygenases are the main mediators of inflammation by catalyzing the initial step of arachidonic acid metabolism and prostaglandin synthesis. The differential expression of the constitutive isoform COX-1 and the inducible isoform COX-2, and the finding that COX-1 is the major form expressed in the gastrointestinal tract, lead to the search for COX-2-selective inhibitors as anti-inflammatory agents that might diminish the gastrointestinal side effects of traditional non-steroidal anti-inflammatory drugs (NSAIDs). COX-2 isoform is expressed predominantly in inflammatory cells and decidedly upregulated in chronic and acute inflammations, becoming a critical target for many pharmacological inhibitors. COX-2 selective inhibitors happen to show equivalent efficacy with that of conventional NSAIDs, but they have reduced gastrointestinal side effects. This review would elucidate the most recent findings on selective COX-2 inhibition and their relevance to human pathology, concretely in inflammatory pathologies characterized by a prolonged pro-inflammatory status, including autoimmune diseases, metabolic syndrome, obesity, atherosclerosis, neurodegenerative diseases, chronic obstructive pulmonary disease, arthritis, chronic inflammatory bowel disease and cardiovascular pathologies.

Pretreatment with Shuanghe-Tang Extract Attenuates Postischemic Brain Injury and Edema in a Mouse Model of Stroke: An Analysis of Medicinal Herbs Listed in Dongui Bogam

Aim

Although stroke is among the leading causes of death and long-term disability, there are few effective treatments for limiting the severity of neurological sequelae. We evaluated the effects of 29 medicinal herbs listed in the Pung chapter of the 17th century Korean medical text Dongui Bogam on stroke symptoms in a mouse model of cerebral ischemia.

Methods

Focal cerebral ischemia was induced via photothrombosis. Infarct volume, brain edema, and neurological deficits were evaluated. Immunofluorescence staining for tight junction proteins and aquaporin 4 (AQP4) was performed following ischemic injury.

Results

Based on our initial findings, we examined the effects of two prescriptions in which the candidate herbs comprised more than 60% of the total formula: Shuanghe-tang and Zengsunsiwu-tang. Pretreatment with Shuanghe-tang significantly reduced infarct volume, decreased blood-brain barrier (BBB) breakdown, attenuated edema, and improved neurological and motor functions in a dose-dependent manner (30, 100, and 300 mg/kg), while no such effects were observed in mice pretreated with Zengsunsiwu-tang. Immunohistochemical analysis revealed significant increases in ipsilateral occludin and zonula occludens 1 (ZO-1) expression in Shuanghe-tang-pretreated mice, as well as increased AQP4 immunofluorescence.

Conclusions

These results indicate that Shuanghe-tang may protect against brain injury and promote recovery of neurological function following ischemia.

Protective effects of Bushen Tiansui decoction on hippocampal synapses in a rat model of Alzheimer's disease

Bushen Tiansui decoction is composed of six traditional Chinese medicines: Herba Epimedii, Radix Polygoni multiflori, Plastrum testudinis, Fossilia Ossis Mastodi, Radix Polygalae, and Rhizoma Acorus tatarinowii. Because Bushen Tiansui decoction is effective against amyloid beta (Aβ) toxicity, we hypothesized that it would reduce hippocampal synaptic damage and improve cognitive function in Alzheimer's disease. To test this hypothesis, we used a previously established animal model of Alzheimer's disease, that is, microinjection of aggregated Aβ25-35 into the bilateral brain ventricles of Sprague-Dawley rats. We found that long-term (28 days) oral administration of Bushen Tiansui decoction (0.563, 1.688, and 3.375 g/mL; 4 mL/day) prevented synaptic loss in the hippocampus and increased the expression levels of synaptic proteins, including postsynaptic density protein 95, the N-methyl-D-aspartate receptor 2B subunit, and Shank1. These results suggested that Bushen Tiansui decoction can protect synapses by maintaining the expression of these synaptic proteins. Bushen Tiansui decoction also ameliorated measures reflecting spatial learning and memory deficits that were observed in the Morris water maze (i.e., increased the number of platform crossings and the amount of time spent in the target quadrant and decreased escape latency) following intraventricular injections of aggregated Aβ25-35 compared with those measures in untreated Aβ25-35-injected rats. Overall, these results provided evidence that further studies on the prevention and treatment of dementia with this traditional Chinese medicine are warranted.

Antineuroinflammatory Effects of Modified Wu-Zi-Yan-Zong Prescription in β-Amyloid-Stimulated BV2 Microglia via the NF-κB and ERK/p38 MAPK Signaling Pathways

Modified Wu-Zi-Yan-Zong prescription (MWP), a traditional Chinese medicinal decoction, has possessed the neuroprotective and anti-inflammatory properties. The mechanisms associated with these properties, however, are not completely understood. We designed the experiments to elucidate the antineuroinflammatory property of MWP in BV2 microglia activated by β-amyloid (Aβ), which is a characteristic feature of Alzheimer's disease (AD). The composition of MWP was studied using HPLC. BV2 microglia cells were then treated with Aβ in the presence or absence of MWP. The effects of MWP treatment on Aβ-activated neuroinflammation were determined using PCR, western blotting, and immunofluorescence staining. MWP significantly inhibited the mRNA expression of inflammatory mediators such as IL-1β, IL-6, TNF-α, and MCP-1, as well as the expression of inducible nitric oxide synthase (iNOS) in Aβ-activated BV2 microglia. MWP also inhibited the nuclear translocation and signaling pathway of nuclear factor kappa B (NF-κB) by suppressing inhibitor of nuclear factor-κB (IκB) degradation and downregulating IκB kinase β (IKKβ) phosphorylation. Moreover, MWP decreased extracellular regulated protein kinase (ERK)/p38 mitogen-activated protein kinase (MAPK) phosphorylation, which is an important signaling pathway for proinflammatory gene expression. We concluded that MWP could suppress neuroinflammatory responses in Aβ-activated BV2 microglia via the NF-κB and ERK/p38 MAPK signaling cascades and could prove an effective therapeutic agent for the prevention and treatment of neuroinflammatory diseases such as AD.

PMC-12, a traditional herbal medicine, enhances learning memory and hippocampal neurogenesis in mice

The beneficial effects of traditional Korean medicine are recognized during the treatment of neurodegenerative conditions, such as, Alzheimer's disease and neurocognitive dysfunction, and recently, hippocampal neurogenesis has been reported to be associated with memory function. In this study, the authors investigated the beneficial effects of polygonum multiflorum Thunberg complex composition-12 (PMC-12), which is a mixture of four medicinal herbs, that is, Polygonum multiflorum, Polygala tenuifolia, Rehmannia glutinosa, and Acorus gramineus, on hippocampal neurogenesis, learning, and memory in mice. PMC-12 was orally administered to male C57BL/6 mice (5 weeks old) at 100 or 500 mg/kg daily for 2 weeks. PMC-12 administration significantly was found to increase the proliferation of neural progenitor cells and the survival of newly-generated cells in the dentate gyrus. In the Morris water maze test, the latency times of PMC-12 treated mice (100 or 500 mg/kg) were shorter than those of vehicle-control mice. In addition, PMC-12 increased the levels of BDNF, p-CREB, and synaptophysin, which are known to be associated with neural plasticity and hippocampal neurogenesis. These findings suggest PMC-12 enhances hippocampal neurogenesis and neurocognitive function and imply that PMC-12 ameliorates memory impairment and cognitive deficits.

Studies on medicinal herbs for cognitive enhancement based on the text mining of Dongeuibogam and preliminary evaluation of its effects

ETHNOPHARMACOLOGICAL RELEVANCE

In literature on Korean medicine, Dongeuibogam (Treasured Mirror of Eastern Medicine), published in 1613, represents the overall results of the traditional medicines of North-East Asia based on prior medicinal literature of this region. We utilized this medicinal literature by text mining to establish a list of candidate herbs for cognitive enhancement in the elderly and then performed an evaluation of their effects.

MATERIALS AND METHODS

Text mining was performed for selection of candidate herbs. Cell viability was determined in HT22 hippocampal cells and immunohistochemistry and behavioral analysis was performed in a kainic acid (KA) mice model in order to observe alterations of hippocampal cells and cognition.

RESULTS

Twenty four herbs for cognitive enhancement in the elderly were selected by text mining of Dongeuibogam. In HT22 cells, pretreatment with 3 candidate herbs resulted in significantly reduced glutamate-induced cell death. Panax ginseng was the most neuroprotective herb against glutamate-induced cell death. In the hippocampus of a KA mice model, pretreatment with 11 candidate herbs resulted in suppression of caspase-3 expression. Treatment with 7 candidate herbs resulted in significantly enhanced expression levels of phosphorylated cAMP response element binding protein. Number of proliferated cells indicated by BrdU labeling was increased by treatment with 10 candidate herbs. Schisandra chinensis was the most effective herb against cell death and proliferation of progenitor cells and Rehmannia glutinosa in neuroprotection in the hippocampus of a KA mice model. In a KA mice model, we confirmed improved spatial and short memory by treatment with the 3 most effective candidate herbs and these recovered functions were involved in a higher number of newly formed neurons from progenitor cells in the hippocampus.

CONCLUSIONS

These established herbs and their combinations identified by text-mining technique and evaluation for effectiveness may have value in further experimental and clinical applications for cognitive enhancement in the elderly.