Ginsenoside Rh2 promotes nonamyloidgenic cleavage of amyloid precursor protein via a cholesterol-dependent pathway

Mechanisms with network pharmacology approach of Ginsenosides in Alzheimer's disease

Alzheimer's disease (AD) is a progressive neurodegenerative disease characterized by memory loss, cognitive disorder, language dysfunction, and mental disability. The main neuropathological changes in AD mainly include amyloid plaque deposition, neurofibrillary tangles, synapse loss, and neuron reduction. However, the current anti-AD drugs do not demonstrate a favorable effect in altering the pathological course of AD. Moreover, long-term use of these drugs is usually accompanied with various side effects. Ginsenosides are the major active constituents of ginseng and have protective effects on AD through various mechanisms in both in vivo and in vitro studies. In this review, we focused on discussing the therapeutic potential effects and the mechanisms of pharmacological activities of ginsenosides in AD, to provide new insight for further research and clinical application of ginsenosides in the future. Recent studies on the pharmacological effects and mechanisms of ginsenosides were retrieved from Chinese National Knowledge Infrastructure, National Science and Technology Library, Wanfang Data, Elsevier, ScienceDirect, PubMed, SpringerLink, and the Web of Science database up to April 2023 using relevant keywords. Network pharmacology and bioinformatics analysis were used to predict the therapeutic effects and mechanisms of ginsenosides against AD. Ginsenosides presented a wide range of therapeutic and biological activities, including alleviating Aβ deposition, decreasing tau hyperphosphorylation, regulating the cholinergic system, resisting oxidative stress, modulating Ca2+ homeostasis, as well as anti-inflammation and anti-apoptosis in neurons, respectively. For further developing the therapeutic potential as well as clinical applications, the network pharmacology approach was combined with a summary of published studies.

American Ginseng for the Treatment of Alzheimer's Disease: A Review

Alzheimer's disease (AD) is a prevalent degenerative condition that is increasingly affecting populations globally. American ginseng (AG) has anti-AD bioactivity, and ginsenosides, as the main active components of AG, have shown strong anti-AD effects in both in vitro and in vivo studies. It has been reported that ginsenosides can inhibit amyloid β-protein (Aβ) production and deposition, tau phosphorylation, apoptosis and cytotoxicity, as well as possess anti-oxidant and anti-inflammatory properties, thus suppressing the progression of AD. In this review, we aim to provide a comprehensive overview of the pathogenesis of AD, the potential anti-AD effects of ginsenosides found in AG, and the underlying molecular mechanisms associated with these effects. Additionally, we will discuss the potential use of AG in the treatment of AD, and how ginsenosides in AG may exert more potent anti-AD effects in vivo may be a direction for further research.

Therapeutic Candidates for Alzheimer's Disease: Saponins

Drug development for Alzheimer's disease, the leading cause of dementia, has been a long-standing challenge. Saponins, which are steroid or triterpenoid glycosides with various pharmacological activities, have displayed therapeutic potential in treating Alzheimer's disease. In a comprehensive review of the literature from May 2007 to May 2023, we identified 63 references involving 40 different types of saponins that have been studied for their effects on Alzheimer's disease. These studies suggest that saponins have the potential to ameliorate Alzheimer's disease by reducing amyloid beta peptide deposition, inhibiting tau phosphorylation, modulating oxidative stress, reducing inflammation, and antiapoptosis. Most intriguingly, ginsenoside Rg1 and pseudoginsenoside-F11 possess these important pharmacological properties and show the best promise for the treatment of Alzheimer's disease. This review provides a summary and classification of common saponins that have been studied for their therapeutic potential in Alzheimer's disease, showcasing their underlying mechanisms. This highlights the promising potential of saponins for the treatment of Alzheimer's disease.

Ginsenoside Rk3 ameliorates Aβ-induced neurotoxicity in APP/PS1 model mice via AMPK signaling pathway

Alzheimer's disease (AD) has become a major public health problem affecting the elderly population, and there is currently no effective treatment. Although the pathogenesis of AD is unclear, neurotoxicity induced by oxidative stress plays an important role in the progression of AD. Ginseng, the root and rhizome of Panax ginseng C. A. Meyer, is used not only as an herbal medicine but also as a functional food to support bodily functions. Ginsenoside Rk3 (Rk3), the main bioactive component in ginseng, has a strong antioxidant effect and has not been reported in AD. In this study, we showed that Rk3 improved neuronal apoptosis, decreased intracellular reactive oxygen species (ROS) production and restored mitochondrial membrane potential in PC12 and primary neuronal cells. In vivo, we found that Rk3 improved spatial learning and memory deficit in precursor protein (APP)/presenilin 1 (PS1) double transgenic mouse model of AD. Additionally, Rk3 increases glutathione reductase (GSH) and superoxide dismutase (SOD) levels while inhibits malondialdehyde (MDA) production, apoptosis and activation of glial cells in APP/PS1 mice. Mechanistically, we found that the protective effect of Rk3 is in correlation with the activation of AMPK/Nrf2 signaling pathway. In conclusion, the findings of this study provide support for Rk3 as a new strategy for the treatment of AD.

Ginseng intake and Alzheimer disease-specific cognition in older adults according to apolipoprotein 4 allele status

Background

The probable association among ginseng intake, Alzheimer's disease (AD)-specific cognition, and apolipoprotein ε4 (APOE4) remains poorly investigated. Hence, we examined the association between ginseng intake and AD-specific cognition in older adults under the moderating effect of APOE4 status.

Methods

This study enrolled 160 adults aged 65-90 years without dementia. All participants underwent comprehensive dietary and clinical assessments including ginseng intake, AD-related cognition (i.e., delayed episodic memory, as the earliest cognitive change in AD), and non-memory cognition for comparative purposes.

Results

Ginseng intake was associated with higher delayed episodic memory, but not non-memory cognition, compared to no ginseng intake. The interaction between ginseng intake and APOE4 status had a significant effect on delayed episodic memory. Subgroup analyses showed that ginseng intake was associated with higher delayed episodic memory in the APOE4-negative but not the APOE4-positive subgroup. The benefits of ginseng intake on delayed episodic memory were prominent in the high duration (≥5 years) and midlife onset (<65 years) groups.

Conclusion

Our study of older adults with no dementia suggests that ginseng intake (with high duration and midlife onset) had a beneficial effect on AD-specific cognitive decline, i.e., the delayed episodic memory. In addition, APOE4 status moderates the association between ginseng intake status and AD-specific cognitive decline.

Potential of ginsenoside Rh2and its derivatives as anti-cancer agents

As a steroid skeleton-based saponin, ginsenoside Rh₂ (G-Rh₂) is one of the major bioactive ginsenosides from the plants of genus Panax L. Many studies have reported the notable pharmacological activities of G-Rh₂ such as anticancer, antiinflammatory, antiviral, antiallergic, antidiabetic, and anti-Alzheimer's activities. Numerous preclinical studies have demonstrated the great potential of G-Rh₂ in the treatment of a wide range of carcinomatous diseases in vitro and in vivo. G-Rh₂ is able to inhibit proliferation, induce apoptosis and cell cycle arrest, retard metastasis, promote differentiation, enhance chemotherapy and reverse multi-drug resistance against multiple tumor cells. The present review mainly summarizes the anticancer effects and related mechanisms of G-Rh₂ in various models as well as the recent advances in G-Rh₂ delivery systems and structural modification to ameliorate its anticancer activity and pharmacokinetics characteristics.

Botanicals and Oral Stem Cell Mediated Regeneration: A Paradigm Shift from Artificial to Biological Replacement

Stem cells are a well-known autologous pluripotent cell source, having excellent potential to develop into specialized cells, such as brain, skin, and bone marrow cells. The oral cavity is reported to be a rich source of multiple types of oral stem cells, including the dental pulp, mucosal soft tissues, periodontal ligament, and apical papilla. Oral stem cells were useful for both the regeneration of soft tissue components in the dental pulp and mineralized structure regeneration, such as bone or dentin, and can be a viable substitute for traditionally used bone marrow stem cells. In recent years, several studies have reported that plant extracts or compounds promoted the proliferation, differentiation, and survival of different oral stem cells. This review is carried out by following the PRISMA guidelines and focusing mainly on the effects of bioactive compounds on oral stem cell-mediated dental, bone, and neural regeneration. It is observed that in recent years studies were mainly focused on the utilization of oral stem cell-mediated regeneration of bone or dental mesenchymal cells, however, the utility of bioactive compounds on oral stem cell-mediated regeneration requires additional assessment beyond in vitro and in vivo studies, and requires more randomized clinical trials and case studies.

Medicine-Food Herbs against Alzheimer’s Disease: A Review of Their Traditional Functional Features, Substance Basis, Clinical Practices and Mechanisms of Action

Alzheimer’s disease (AD) is a progressive, neurodegenerative disorder that currently has reached epidemic proportions among elderly populations around the world. In China, available traditional Chinese medicines (TCMs) that organically combine functional foods with medicinal values are named “Medicine Food Homology (MFH)”. In this review, we focused on MFH varieties for their traditional functional features, substance bases, clinical uses, and mechanisms of action (MOAs) for AD prevention and treatment. We consider the antiAD active constituents from MFH species, their effects on in vitro/in vivo AD models, and their drug targets and signal pathways by summing up the literature via a systematic electronic search (SciFinder, PubMed, and Web of Science). In this paper, several MFH plant sources are discussed in detail from in vitro/in vivo models and methods, to MOAs. We found that most of the MFH varieties exert neuroprotective effects and ameliorate cognitive impairments by inhibiting neuropathological signs (Aβ-induced toxicity, amyloid precursor protein, and phosphorylated Tau immunoreactivity), including anti-inflammation, antioxidative stress, antiautophagy, and antiapoptosis, etc. Indeed, some MFH substances and their related phytochemicals have a broad spectrum of activities, so they are superior to simple single-target drugs in treating chronic diseases. This review can provide significant guidance for people’s healthy lifestyles and drug development for AD prevention and treatment.

Ginseng extract and ginsenosides improve neurological function and promote antioxidant effects in rats with spinal cord injury: A meta-analysis and systematic review

Spinal cord injury (SCI) is defined as damage to the spinal cord that temporarily or permanently changes its function. There is no definite treatment established for neurological complete injury patients. This study investigated the effect of ginseng extract and ginsenosides on neurological recovery and antioxidant efficacies in rat models following SCI and explore the appropriate dosage. Searches were done on PubMed, Embase, and Chinese databases, and animal studies matches the inclusion criteria were selected. Pair-wise meta-analysis and subgroup analysis were performed. Ten studies were included, and the overall methodological qualities were low quality. The result showed ginseng extract and ginsenosides significantly improve neurological function, through the Basso, Beattie, and Bresnahan (BBB) locomotor rating scale (pooled MD = 4.40; 95% CI = 3.92 to 4.88; p < 0.00001), significantly decrease malondialdehyde (MDA) (n = 290; pooled MD = −2.19; 95% CI = −3.16 to −1.22; p < 0.0001) and increase superoxide dismutase (SOD) levels (n = 290; pooled MD = 2.14; 95% CI = 1.45 to 2.83; p < 0.00001). Both low (<25 mg/kg) and high dosage (≥25 mg/kg) showed significant improvement in the motor function recovery in SCI rats. Collectively, this review suggests ginseng extract and ginsenosides has a protective effect on SCI, with good safety and a clear mechanism of action and may be suitable for future clinical trials and applications.

Leveraging hallmark Alzheimer's molecular targets using phytoconstituents: Current perspective and emerging trends

Alzheimer's disease (AD), a type of dementia, severely distresses different brain regions. Characterized by various neuropathologies, it interferes with cognitive functions and neuropsychiatrical controls. This progressive deterioration has negative impacts not only on an individual's daily activity but also on social and occupational life. The pharmacological approach has always remained in the limelight for the treatment of AD. However, this approach is condemned with several side effects. Henceforth, a change in treatment approach has become crucial. Plant-based natural products are garnering special attention due to lesser side effects associated with their use. The current review emphasizes the anti-AD properties of phytoconstituents, throws light on those under clinical trials, and compiles information on their specific mode of actions against AD-related different neuropathologies. The phytoconstituents alone or in combinations will surely help discover new potent drugs for the effective treatment of AD with lesser side effects than the currently available pharmacological treatment.

Lipid Membranes as Key Targets for the Pharmacological Actions of Ginsenosides

In this review, we will focus on the activity of ginsenosides on membranes and their related effects, from physicochemical, biophysical, and pharmacological viewpoints. Ginsenosides are a class of saponins with a large structural diversity and a wide range of pharmacological effects. These effects can at least partly be related to their activity on membranes which results from their amphiphilic character. Some ginsenosides are able to interact with membrane lipids and associate into nanostructures, making them possible adjuvants for vaccines. They are able to modulate membrane biophysical properties such as membrane fluidity, permeability or the formation of lateral domains with some degree of specificity towards certain cell types such as bacteria, fungi, or cancer cells. In addition, they have shown antioxidant properties which protect membranes from lipid oxidation. They further displayed some activity on membrane proteins either through direct or indirect interaction. We investigate the structure activity relationship of ginsenosides on membranes and discuss the implications and potential use as anticancer, antibacterial, and antifungal agents.

Therapeutic Effects of Natural Drugs on Alzheimer's Disease

Alzheimer disease (AD) is characterized as a chronic neurodegenerative disease associated with aging. The clinical manifestations of AD include latent episodes of memory and cognitive impairment, psychiatric symptoms and behavioral disorders, as well as limited activities in daily life. In developed countries, AD is now acknowledged as the third leading cause of death, following cardiovascular disease and cancer. The pathogenesis and mechanism of AD remain unclear, although some theories have been proposed to explain AD, such as the theory of β-amyloid, the theory of the abnormal metabolism of tau protein, the theory of free radical damage, the theory of the inflammatory response, the theory of cholinergic damage, etc. Effective methods to predict, prevent or reverse AD are unavailable, and thus the development of new, efficient therapeutic drugs has become a current research hot spot worldwide. The isolation and extraction of active components from natural drugs have great potential in treating AD. These drugs possess the advantages of multiple targets in multiple pathways, fewer side effects and a long duration of curative effects. This article summaries the latest research progress regarding the mechanisms of natural drugs in the treatment of AD, providing a review of the literature and a theoretical basis for improving the clinical treatment of AD.

Understanding the complexity of the matrix metalloproteinase system and its relevance to age-related diseases: Age-related macular degeneration and Alzheimer's disease

Extracellular matrices (ECMs) are maintained by tightly coupled processes of continuous synthesis and degradation. The degradative arm is mediated by a family of proteolytic enzymes called the matrix metalloproteinases (MMPs). These enzymes are released as latent proteins (pro-MMPs) and on activation are capable of degrading most components of an ECM. Activity of these enzymes is checked by the presence of tissue inhibitors of MMPs (TIMPs) and current opinion holds that the ratio of TIMPs/MMPs determines the relative rate of degradation. Thus, elevated ratios are thought to compromise degradation leading to the accumulation of abnormal ECM material, whilst diminished ratios are thought to lead to excessive ECM degradation (facilitating angiogenesis and the spread of cancer cells). Our recent work has shown this system to be far more complex. MMP species tend to undergo covalent modification leading to homo- and hetero-dimerization and aggregation resulting in the formation of very large macromolecular weight MMP complexes (LMMCs). In addition, the various MMP species also show a bound-free compartmentalisation. The net result of these changes is to reduce the availability of the latent forms of MMPs for the activation process. An assessment of the degradation potential of the MMP system in any tissue must therefore take into account the degree of sequestration of the latent MMP species, a protocol that has not previously been addressed. Taking into consideration the complexities already described, we will present an analysis of the MMP system in two common neurodegenerative disorders, namely age-related macular degeneration (AMD) and Alzheimer's disease (AD).

Panax ginseng components and the pathogenesis of Alzheimer's disease (Review)

Ginseng is one of the main representatives of traditional Chinese medicine and presents a wide range of pharmacological actions. Ginsenosides are the main class of active compounds found in ginseng. They demonstrate unique biological activity and medicinal value, namely anti-tumour, anti-inflammatory and antioxidant properties, as well as anti-apoptotic properties. Increasing levels of stress in life are responsible for the increased incidence of nervous system diseases. Neurological diseases create a huge burden on the lives and health of individuals. In recent years, studies have indicated that ginsenosides play a pronounced positive role in the prevention and treatment of neurological diseases. Nevertheless, research is still at an early stage of development, and the complex mechanisms of action involved remain largely unknown. This review aimed to shed light into what is currently known about the mechanisms of action of ginsenosides in relation to Alzheimer's disease. Scientific material and theoretical bases for the treatment of nervous system diseases with purified Panax ginseng extracts are also discussed.

Ginseng: A Qualitative Review of Benefits for Palliative Clinicians

Ginseng has been used for centuries to treat various diseases and has been commercially developed and cultivated in the past 300 years. Ginseng products may be fresh, dried (white), or dried and steamed (red). Extracts may be made using water or alcohol. There are over 50 different ginsenosides identified by chromatography. We did an informal systematic qualitative review that centered on fatigue, cancer, dementia, respiratory diseases, and heart failure, and we review 113 studies in 6 tables. There are multiple potential benefits to ginseng in cancer. Ginseng, in certain circumstances, has been shown to improve dementia, chronic obstructive pulmonary disease, and heart failure through randomized trials. Most trials had biases or unknown biases and so most evidence is of low quality. We review the gaps in the evidence and make some recommendations regarding future studies.

Panax ginseng as an adjuvant treatment for Alzheimer's disease

Longevity in medicine can be defined as a long life without mental or physical deficits. This can be prevented by Alzheimer's disease (AD). Current conventional AD treatments only alleviate the symptoms without reversing AD progression. Recent studies demonstrated that Panax ginseng extract improves AD symptoms in patients with AD, and the two main components of ginseng might contribute to AD amelioration. Ginsenosides show various AD-related neuroprotective effects. Gintonin is a newly identified ginseng constituent that contains lysophosphatidic acids and attenuates AD-related brain neuropathies. Ginsenosides decrease amyloid β-protein (Aβ) formation by inhibiting β- and γ-secretase activity or by activating the nonamyloidogenic pathway, inhibit acetylcholinesterase activity and Aβ-induced neurotoxicity, and decrease Aβ-induced production of reactive oxygen species and neuroinflammatory reactions. Oral administration of ginsenosides increases the expression levels of enzymes involved in acetylcholine synthesis in the brain and alleviates Aβ-induced cholinergic deficits in AD models. Similarly, gintonin inhibits Aβ-induced neurotoxicity and activates the nonamyloidogenic pathway to reduce Aβ formation and to increase acetylcholine and choline acetyltransferase expression in the brain through lysophosphatidic acid receptors. Oral administration of gintonin attenuates brain amyloid plaque deposits, boosting hippocampal cholinergic systems and neurogenesis, thereby ameliorating learning and memory impairments. It also improves cognitive functions in patients with AD. Ginsenosides and gintonin attenuate AD-related neuropathology through multiple routes. This review focuses research demonstrating that ginseng constituents could be a candidate as an adjuvant for AD treatment. However, clinical investigations including efficacy and tolerability analyses may be necessary for the clinical acceptance of ginseng components in combination with conventional AD drugs.

Ginsenosides: the need to move forward from bench to clinical trials

Panax ginseng, known as Koran ginseng, one of the most commonly used traditional plants, has been demonstrated to show a wide range of pharmacological applications. Ginsenosides are the major active ingredients found in ginseng and are responsible for the biological and pharmacological activities, such as antioxidation, antiinflammation, vasorelaxation, and anticancer actions. Existing studies have mostly focused on identifying and purifying single ginsenosides and investigating pharmacological activities and molecular mechanisms in cells and animal models. However, ginsenoside studies based on clinical trials have been very limited. Therefore, this review aimed to discuss the currently available clinical trials on ginsenosides and provide insights and future directions for developing ginsenosides as efficacious and safe drugs for human disease.

Ginsenoside Rh2 reverses sleep deprivation-induced cognitive deficit in mice

Sleep deprivation (SD) negatively caused cognitive deficit, which was associated with oxidative stress induced damage. Ginsenoside Rh2 had the ability to protect against damage caused by reactive oxygen species in vitro, showing antioxidant property. Therefore, it was hypothesized that Ginsenoside Rh2 could prevent SD-induced cognitive deficit via its antioxidant properties. In this study, the effect of Ginsenoside Rh2 on memory impairment induced by sleep deprivation was investigated. The mice were sleep deprived continuously for 14 days using our self-made Sleep Interruption Apparatus (SIA). Ginsenoside Rh2 was administered intraperitoneally at two doses (20 and 40 μmol/kg) for 20 days. Thereafter, behavioral studies were conducted to test the learning and memory ability using object location recognition (OLR) experiment and passive avoidance (PA) test. Additionally, the oxidative stress parameters in the serum and the brain tissues (cortex and hippocampus) were assessed, including the superoxide dismutase (SOD) enzyme activity, the total antioxidant reactivity (TAR), the malondialdehyde (MDA) level, the glutathione (GSH) level, and the lipid peroxidation (LPO) content. The results revealed that SD impaired both spatial and non-spatial memory (P < 0.05). Treatment with Ginsenoside Rh2 at both doses prevented memory impairment induced by SD. Moreover, Ginsenoside Rh2 normalized the reduction of SOD and TAR activities in the serum (P < 0.01) and the decrease of GSH content in both the cortex and hippocampus (P < 0.05) induced by SD. Furthermore, Ginsenoside Rh2 significantly decreased the MDA level in the serum (P < 0.05) and the LPO content in both the cortex and hippocampus (P < 0.05) compared to SD group. In conclusion, sleep deprivation impaired both spatial and non-spatial memory and Ginsenoside Rh2 reversed this impairment, probably by preventing the oxidative stress damage in the body, including the serum and brain during sleep deprivation.

Evaluation of structure–activity relationships of ginsenosides against amyloid β induced pathological behaviours in transgenic Caenorhabditis elegans

The systematic in vivo study comparing the effects of different ginsenosides on Aβ induced toxicity and cognitive impairment.

Ginsenoside Rg1 ameliorates hippocampal long-term potentiation and memory in an Alzheimer's disease model

The complex etiopathogenesis of Alzheimer's disease (AD) has limited progression in the identification of effective therapeutic agents. Amyloid precursor protein (APP) and presenilin‑1 (PS1) are always overexpressed in AD, and are considered to be the initiators of the formation of β‑amyloid plaques and the symptoms of AD. In the present study, a transgenic AD model, constructed via the overexpression of APP and PS1, was used to verify the protective effects of ginsenoside Rg1 on memory performance and synaptic plasticity. AD mice (6‑month‑old) were treated via intraperitoneal injection of 0.1‑10 mg/kg ginsenoside Rg1. Long‑term memory, synaptic plasticity, and the levels of AD‑associated and synaptic plasticity‑associated proteins were measured following treatment. Memory was measured using a fear conditioning task and protein expression levels were investigated using western blotting. All the data was analyzed by one-way analysis of variance or t‑test. Following 30 days of consecutive treatment, memory in the AD mouse model was ameliorated in the 10 mg/kg ginsenoside Rg1 treatment group. As demonstrated by biochemical experiments, ginsenoside Rg1 treatment reduced the accumulations of β‑amyloid 1‑42 and phosphorylated (p)‑Tau in the AD model. Additionally, brain-derived neurotrophic factor (BDNF) and p‑TrkB synaptic plasticity‑associated proteins were upregulated following ginsenoside Rg1 application. Correspondingly, long‑term potentiation (LTP) was restored following ginsenoside Rg1 application in the AD mice model. Taken together, ginsenoside Rg1 repaired hippocampal LTP and memory, likely through facilitating the clearance of AD‑associated proteins and through activation of the BDNF‑TrkB pathway. Therefore, ginsenoside Rg1 may be a candidate drug for the treatment of AD.

The impact of ginsenosides on cognitive deficits in experimental animal studies of Alzheimer's disease: a systematic review

Background

The efficacy of ginsenoside treatment on cognitive decline in individuals with Alzheimer’s disease (AD) has yet to be investigated. In this protocal, we conducted a systematic review to evaluate the effect of ginsenosides on cognitive deficits in experimental rodent AD models.

Methods

We identified eligible studies by searching seven electronic databases spanning from January 1980 to October 2014. We assessed the study quality, evaluated the efficacy of ginsenoside treatment, and performed a stratified meta-analysis and meta-regression analysis to assess the influence of the study design on ginsenoside efficacy.

Results

Twelve studies fulfilled our inclusion criteria from a total of 283 publications. The overall methodological quality of these studies was poor. The meta-analysis revealed that ginsenosides have a statistically significant positive effect on cognitive performance in experimental AD models. The stratified analysis revealed that ginsenoside Rg1 had the greatest effect on acquisition and retention memory in AD models. The effect size was significantly higher for both acquisition and retention memory in studies that used female animals compared with male animals.

Conclusions

We conclude that ginsenosides might reduce cognitive deficits in AD models. However, additional well-designed and well-reported animal studies are needed to inform further clinical investigations.

Protective effects of ginseng on neurological disorders

Ginseng (Order: Apiales, Family: Araliaceae, Genus: Panax) has been used as a traditional herbal medicine for over 2000 years, and is recorded to have antianxiety, antidepressant and cognition enhancing properties. The protective effects of ginseng on neurological disorders are discussed in this review. Ginseng species and ginsenosides, and their intestinal metabolism and bioavailability are briefly introduced. This is followed by molecular mechanisms of effects of ginseng on the brain, including glutamatergic transmission, monoamine transmission, estrogen signaling, nitric oxide (NO) production, the Keap1/Nrf2 adaptive cellular stress pathway, neuronal survival, apoptosis, neural stem cells and neuroregeneration, microglia, astrocytes, oligodendrocytes and cerebral microvessels. The molecular mechanisms of the neuroprotective effects of ginseng in Alzheimer’s disease (AD) including β-amyloid (Aβ) formation, tau hyperphosphorylation and oxidative stress, major depression, stroke, Parkinson’s disease and multiple sclerosis are presented. It is hoped that this discussion will stimulate more studies on the use of ginseng in neurological disorders.