Ginsenoside Compound K Regulates Amyloid β via the Nrf2/Keap1 Signaling Pathway in Mice with Scopolamine Hydrobromide-Induced Memory Impairments

Ginsenoside Re Regulates Oxidative Stress through the PI3K/Akt/Nrf2 Signaling Pathway in Mice with Scopolamine-Induced Memory Impairments

While Ginsenoside Re has been shown to protect the central nervous system, reports of its effects on memory in the model of scopolamine-induced memory impairment are rare. The aim of this study was to investigate the effects of Ginsenoside Re on scopolamine (SCOP)-induced memory damage and the mechanism of action. Male ICR mice were treated with SCOP (3 mg/kg) for 7 days and with or without Ginsenoside Re for 14 days. As evidenced by behavioral studies (escape latency and cross platform position), brain tissue morphology, and oxidative stress indicators after Ginsenoside Re treatment, the memory damage caused by SCOP was significantly ameliorated. Further mechanism research indicated that Ginsenoside Re inhibited cell apoptosis by regulating the PI3K/Akt/Nrf2 pathway, thereby exerting a cognitive impairment improvement effect. This research suggests that Ginsenoside Re could protect against SCOP-induced memory defects possibly through inhibiting oxidative stress and cell apoptosis.

Structural Characters and Pharmacological Activity of Protopanaxadiol-Type Saponins and Protopanaxatriol-Type Saponins from Ginseng

Ginseng has a long history of drug application in China, which can treat various diseases and achieve significant efficacy. Ginsenosides have always been deemed important ingredients for pharmacological activities. Based on the structural characteristics of steroidal saponins, ginsenosides are mainly divided into protopanaxadiol-type saponins (PDS, mainly including Rb1, Rb2, Rd, Rc, Rh2, CK, and PPD) and protopanaxatriol-type saponins (PTS, mainly including Re, R1, Rg1, Rh1, Rf, and PPT). The structure differences between PDS and PTS result in the differences of pharmacological activities. This paper provides an overview of PDS and PTS, mainly focusing on their chemical profile, pharmacokinetics, hydrolytic metabolism, and pharmacological activities including antioxidant, antifatigue, antiaging, immunodulation, antitumor, cardiovascular protection, neuroprotection, and antidiabetes. It is intended to contribute to an in-depth study of the relationship between PDS and PTS.

Advancements in research on the effects of panax notoginseng saponin constituents in ameliorating learning and memory disorders

Learning and memory disorder is a cluster of symptoms caused by neuronal aging and other diseases of the central nervous system (CNS). Panax notoginseng saponins (PNS) are a series of saponins derived from the natural active ingredients of traditional Chinese medicine (TCM) that have neuroprotective effects on the central nervous system. In this paper, we review the ameliorative effects and mechanisms of Panax notoginseng saponin-like components on learning and memory disorders to provide valuable references and insights for the development of new drugs for the treatment of learning and memory disorders. Our summary results suggest that Panax ginseng saponins have significant effects on improving learning and memory disorders, and these effects and potential mechanisms are mediated by their anti-inflammatory, anti-apoptotic, antioxidant, β-amyloid lowering, mitochondrial homeostasis in vivo, neuronal structure and function improving, neurogenesis promoting, neurotransmitter release regulating, and probiotic homeostasis in vivo activities. These findings suggest the potential of Panax notoginseng saponin-like constituents as drug candidates for improving learning and memory disorders.

Structural Characters and Pharmacological Activity of Protopanaxadiol‐Type Saponins and Protopanaxatriol‐Type Saponins from Ginseng

Ginseng has a long history of drug application in China, which can treat various diseases and achieve significant efficacy. Ginsenosides have always been deemed important ingredients for pharmacological activities. Based on the structural characteristics of steroidal saponins, ginsenosides are mainly divided into protopanaxadiol‐type saponins (PDS, mainly including Rb1, Rb2, Rd, Rc, Rh2, CK, and PPD) and protopanaxatriol‐type saponins (PTS, mainly including Re, R1, Rg1, Rh1, Rf, and PPT). The structure differences between PDS and PTS result in the differences of pharmacological activities. This paper provides an overview of PDS and PTS, mainly focusing on their chemical profile, pharmacokinetics, hydrolytic metabolism, and pharmacological activities including antioxidant, antifatigue, antiaging, immunodulation, antitumor, cardiovascular protection, neuroprotection, and antidiabetes. It is intended to contribute to an in‐depth study of the relationship between PDS and PTS.

Active Compounds of Panax ginseng in the Improvement of Alzheimer's Disease and Application of Spatial Metabolomics

Panax ginseng C.A. Meyer (P. ginseng) is one of the more common traditional Chinese medicines (TCMs). It contains numerous chemical components and exhibits a range of pharmacological effects. An enormous burden is placed on people's health and life by Alzheimer's disease (AD), a neurodegenerative condition. Recent research has shown that P. ginseng's chemical constituents, particularly ginsenosides, have a significant beneficial impact on the prevention and management of neurological disorders. To understand the current status of research on P. ginseng to improve AD, this paper discusses the composition of P. ginseng, its mechanism of action, and its clinical application. The pathogenesis of AD includes amyloid beta protein (Aβ) generation and aggregation, tau protein hyperphosphorylation, oxidant stress, neuroinflammation, mitochondrial damage, and neurotransmitter and gut microbiota disorders. This review presents the key molecular mechanisms and signaling pathways of the active ingredients in P. ginseng involved in improving AD from the perspective of AD pathogenesis. A P. ginseng-related signaling pathway network was constructed to provide effective targets for the treatment of AD. In addition, the application of spatial metabolomics techniques in studying P. ginseng and AD is discussed. In summary, this paper discusses research perspectives for the study of P. ginseng in the treatment of AD, including a systematic and in-depth review of the mechanisms of action of the active substances in P. ginseng, and evaluates the feasibility of applying spatial metabolomics in the study of AD pathogenesis and pharmacological treatment.

Biotransformation of American Ginseng Stems and Leaves by an Endophytic Fungus Umbelopsis sp. and Its Effect on Alzheimer's Disease Control

BACKGROUND

Common ginsenosides can be transformed into rare ginsenosides through microbial fermentation, and some rare ginsenosides can prevent Alzheimer's disease (AD). This study aimed to transform common ginsenosides into rare ginsenosides through solid-state fermentation of American ginseng stems and leaves (AGSL) by an endophytic fungus and to explore whether fermented saponin extracts prevent AD.

METHODS

The powders of AGSL were fermented in a solid state by endophytic fungus. Total saponins were extracted from fermentation products using the methanol extraction method. The types of saponins were analyzed by liquid chromatography mass spectrometry (LC/MS). The Aβ42 concentration and β-secretase activity were measured by ELISA for the prevention of AD.

RESULTS

After AGSL was fermented by an endophytic fungus NSJG, the total saponin concentration of the fermented extract G-SL was higher than the unfermented CK-SL. Rare ginsenoside Rh1 was newly produced and the yield of compound K (561.79%), Rh2 (77.48%), and F2 (40.89%) was increased in G-SL. G-SL had a higher inhibition rate on Aβ42 concentration (42.75%) and β-secretase activity (42.22%) than CK-SL, possibly because the rare ginsenoside Rh1, Rh2, F2, and compound K included in it have a strong inhibitory effect on AD.

CONCLUSION

The fermented saponin extracts of AGSL show more inhibition effects on AD and may be promising therapeutic drugs or nutrients for AD.

Anti-Aging Activity and Modes of Action of Compounds from Natural Food Sources

Aging is a natural and inescapable phenomenon characterized by a progressive deterioration of physiological functions, leading to increased vulnerability to chronic diseases and death. With economic and medical development, the elderly population is gradually increasing, which poses a great burden to society, the economy and the medical field. Thus, healthy aging has now become a common aspiration among people over the world. Accumulating evidence indicates that substances that can mediate the deteriorated physiological processes are highly likely to have the potential to prolong lifespan and improve aging-associated diseases. Foods from natural sources are full of bioactive compounds, such as polysaccharides, polyphenols, carotenoids, sterols, terpenoids and vitamins. These bioactive compounds and their derivatives have been shown to be able to delay aging and/or improve aging-associated diseases, thereby prolonging lifespan, via regulation of various physiological processes. Here, we summarize the current understanding of the anti-aging activities of the compounds, polysaccharides, polyphenols, carotenoids, sterols, terpenoids and vitamins from natural food sources, and their modes of action in delaying aging and improving aging-associated diseases. This will certainly provide a reference for further research on the anti-aging effects of bioactive compounds from natural food sources.

Ginsenoside CK targeting KEAP1-DGR/Kelch domain disrupts the binding between KEAP1 and NRF2-DLG motif to ameliorate oxidative stress damage

BACKGROUND

Panax ginseng and Panax notoginseng as traditional Chinese medicines, are widely used in the treatment of qi deficiency, viral or bacterial infection, inflammation and cancer. Ginsenoside CK, an active metabolite of protopanoxadiol among the ginseng saponins, has been shown in previous studies to improve the organism's oxidative balance by regulating the KEAP1-NRF2/ARE pathway, thus slowing the progression of diseases. However, the specific targets and mechanisms of CK in improving oxidative stress remain unclear.

PURPOSE

The aim of this study was to determine the potential therapeutic targets and molecular mechanisms of CK in improving oxidative stress injury both in vitro and in vivo.

METHODS

LPS was used to induce oxidative damage in RAW 264.7 cells to evaluate the regulatory effects of CK on the KEAP1-NRF2/ARE pathway. Drug affinity responsive target stability technology (DARTS) combined with proteomics was employed to identify CK's potential target proteins. CK functional probe were designed to analyze the target protein using click chemistry. Furthermore, small molecule and protein interaction technologies were used to verify the mechanism, and computer dynamic simulation technology was used to analyze the interaction sites between CK and the target protein. The pharmacological effects and mechanism of CK in improving oxidative damage were verified in vivo by LPS-induced acute injury in mice and physical mechanical injury in rat soft tissues.

RESULTS

KEAP1 was identified as the target protein that CK regulates to improve oxidative damage through the KEAP1-NRF2/ARE pathway. CK competitively binds to the DGR/Kelch domain of KEAP1, disrupting the binding between DLG peptide in NRF2 and KEAP1, thereby inhibiting the occurrence of oxidative damage induced by LPS or physical mechanical stress.

CONCLUSIONS

CK functions as a natural KEAP1-NRF2 inhibitor, disrupting the binding between KEAP1 and NRF2-DLG motifs by targeting the DGR/Kelch domain of KEAP1, activating the antioxidant transcriptional program of NRF2, and reducing oxidative stress damage.

Protective effects of ginseng and ginsenosides in the development of osteoarthritis (Review)

Osteoarthritis (OA) is a chronic inflammatory joint disease. Traditional chinese medicine provides a resource for drug screening for OA treatment. Ginseng and the associated bioactive compound, ginsenosides, may reduce inflammation, which is considered a risk factor for the development of OA. Specifically, ginsenosides may exhibit anti-inflammatory and anti-oxidative stress activities, and inhibit extracellular matrix degradation by suppressing the NF-κB and MAPK signaling pathways. Notably, specific ginsenosides, such as compound K and Rk1, may physically interact with IκB kinase and inhibit the associated phosphorylation. Thus, ginsenosides exhibit potential as therapeutic candidates in the management of OA. However, the low water solubility limits the clinical applications of ginsenosides. Numerous effective strategies have been explored to improve bioavailability; however, further investigations are still required.

The Mitochondrial-Derived Peptide (MOTS-c) Interacted with Nrf2 to Defend the Antioxidant System to Protect Dopaminergic Neurons Against Rotenone Exposure

MOTS-c is a 16-amino acid mitochondrial-derived peptide reported to be involved in regulating energy metabolism. However, few studies have reported the role of MOTS-c on neuron degeneration. In this study, it was aimed to explore the action of MOTS-c in rotenone-induced dopaminergic neurotoxicity. In an in vitro study, it was observed that rotenone could influence the expression and localization of MOTS-c significantly in PC12 cells, with more MOTS-c translocating into the nucleus from mitochondria. Further study showed that the translocation of MOTS-c from the mitochondria into the nucleus could directly interact with Nrf2 to regulate HO-1 and NQO1 expression in PC12 cells exposed to rotenone, which had been suggested to be involved in the antioxidant defense system. In vivo and in vitro experiments demonstrated that exogenous MOTS-c pretreatment could protect PC12 cells and rats from mitochondrial dysfunction and oxidative stress induced by rotenone. Moreover, MOTS-c pretreatment significantly decreased the loss of TH, PSD95, and SYP protein expression in the striatum of rats exposed to rotenone. In addition, MOTS-c pretreatment could clearly alleviate the downregulated expression of Nrf2, HO-1, and NQO1, as well as the upregulated Keap1 protein expression in the striatum of rotenone-treated rats. Taken together, these findings suggested that MOTS-c could directly interact with Nrf2 to activate the Nrf2/HO-1/NQO1 signal pathway to defend the antioxidant system to prevent dopaminergic neurons from rotenone-induced oxidative stress and neurotoxicity in vitro and in vivo.

Standardized extract of Glehnia Littoralis abrogates memory impairment and neuroinflammation by regulation of CREB/BDNF and NF-κB/MAPK signaling in scopolamine-induced amnesic mice model

Mild cognitive impairment is a typical symptom of early Alzheimer's disease (AD). Glehnia littoralis (G. littoralis), a medicinal halophyte plant commonly used to treat strokes, has been shown to possess some therapeutic qualities. In this study, we investigated the neuroprotective and anti-neuroinflammatory effects of a 50% ethanol extract of G. littoralis (GLE) on lipopolysccharide (LPS)-stimulated BV-2 cells and scopolamine-induced amnesic mice. In the in vitro study, GLE treatment (100, 200, and 400 µg/mL) markedly attenuated the translocation of NF-κB to the nucleus concomitantly with the significant mitigation of the LPS-induced production of inflammatory mediators, including NO, iNOS, COX-2, IL-6, and TNF-α. In addition, the GLE treatment suppressed the phosphorylation of MAPK signaling in the LPS-stimulated BV-2 cells. In the in vivo study, mice were orally administered with the GLE (50, 100, and 200 mg/kg) for 14 days, and cognitive loss was induced via the intraperitoneal injection of scopolamine (1 mg/kg) from 8 to 14 days. We found that GLE treatment ameliorated memory impairment and simultaneously improved memory function in the scopolamine-induced amnesic mice. Correspondingly, GLE treatment significantly decreased the AChE level and upregulated the protein expression of neuroprotective markers, such as BDNF and CREB, as well as Nrf2/HO-1 and decreased the levels of iNOS and COX-2 in the hippocampus and cortex. Furthermore, GLE treatment attenuated the increased phosphorylation of NF-κB/MAPK signaling in the hippocampus and cortex. These results suggest that GLE has a potential neuroprotective activity that may ameliorate learning and memory impairment by regulating AChE activity, promoting CREB/BDNF signaling, and inhibiting NF-κB/MAPK signaling and neuroinflammation.

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.

Natural antioxidants that act against Alzheimer's disease through modulation of the NRF2 pathway: a focus on their molecular mechanisms of action

Characterized by a complex pathophysiology that includes the intraneuronal formation of neurofibrillary tangles and the extracellular deposition of β-amyloid plaques, Alzheimer's disease (AD) is a terminal neurodegenerative disease that causes dementia in older adults. Oxidative stress in the brain is considered as one of the contributing factors to the pathogenesis of AD, and thus, antioxidants have attracted much interest as potential therapeutic agents against the disorder. Natural antioxidants are typically characterized by low acute and chronic toxicity, which facilitates their potential therapeutic application. One important molecular target for the beneficial effects of natural antioxidants is the nuclear factor erythroid-derived 2-related factor 2 (NFE2L2/NRF2). NRF2 is a key transcription factor that orchestrates the cellular antioxidant response through regulating the expression of oxidative stress-related genes harboring the antioxidant response element (ARE) in their promoters. Indeed, in the case of excessive oxidative damage, NRF2 migrates to the nucleus and binds to ARE, activating the transcription of antioxidant protector genes. There is increasing evidence that NRF2 is implicated in AD pathology through dysfunction and altered localization, which renders it as a potential therapeutic target for AD. Thus, this review summarizes the most recent (2018-2023) advances on the NRF2-modulating activity of natural antioxidants observed in vitro and in AD animal models. This information will help elucidate the molecular mechanisms governing the antioxidant activity of such phytochemicals to highlight their therapeutic potential against common neurodegenerative diseases, such as AD.

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.

Leonurine Alleviates Cognitive Dysfunction and Reduces Oxidative Stress by Activating Nrf-2 Pathway in Alzheimer's Disease Mouse Model

Introduction

Alzheimer's disease (AD) is the most common type of dementia, impacting approximately 50 million individuals globally. However, the current treatments available for AD are only symptomatic and have limited efficacy. This study aimed to investigate whether Leonurine could alleviate cognitive dysfunction in a mouse model of AD and explore its underlying molecular mechanisms.

Methods

In this study, male APP/PS1 mice were orally administered Leonurine for two consecutive months. The cognitive functions of the mice were then evaluated using novel object recognition (NOR) and Morris water maze (MWM) tests. Hippocampal neuronal damage was observed through Nissl staining, Aβ levels were determined through ELISA, oxidative stress activity was detected through biochemical methods, and the nuclear factor erythroid-2-related factor 2 (Nrf-2) pathway was analyzed using western blot and real-time quantitative polymerase chain reaction analysis.

Results

Our results demonstrated that Leonurine treatment markedly improved cognitive functions, as indicated by the improved performance in the model. Additionally, histopathology showed a reduction in hippocampal neuronal damage. This can be attributed to the potential of Leonurine to reduce Aβ1-40 and Aβ1-42 levels and alleviate oxidative stress. Its antioxidant effect is linked to the activation of the Nrf-2 signaling pathway in APP/PS1 mice, which promotes Nrf-2 nuclear translocation and expression of HO-1 and NQO-1.

Conclusion

These findings suggest that Leonurine could be explored further as it could emerge as a promising drug for AD treatment.

Nrf2-mediated activation of HO-1 is required in the blocking effect of compound K, a ginseng saponin metabolite, against oxidative stress damage in ARPE-19 human retinal pigment epithelial cells

Background

The beneficial effects of compound K (CK) on different chronic diseases have been shown to be at least related to antioxidant action. Nevertheless, since its antioxidant activity in human retinal pigment epithelial (RPE) cells is still unknown, here we investigated whether CK alleviates oxidative stress-stimulated damage in RPE ARPE-19 cells.

Methods

The cytoprotective consequence of CK in hydrogen peroxide (H₂O₂)-treated cells was evaluated by cell viability, DNA damage, and apoptosis assays. Fluorescence analysis and immunoblotting were performed to investigate the inhibitory action of CK on reactive oxygen species (ROS) production and mitochondrial dysfunction.

Results

H₂O₂-promoted cytotoxicity, oxidative stress, DNA damage, mitochondrial impairment, and apoptosis were significantly attenuated by CK in ARPE-19 cells. Furthermore, nuclear factor erythroid 2-related factor 2 (Nrf2) phosphorylation level and its shuttling to the nucleus were increased, which was correlated with upregulated activation of heme oxygenase-1 (HO-1). However, zinc protoporphyrin, a blocker of HO-1, significantly abrogated the preventive action of CK in H₂O₂-treated ARPE-19 cells.

Conclusion

This study indicates that activation of Nrf2/HO-1 signaling by CK plays an important role in rescuing ARPE-19 cells from oxidative cellular damage.

Natural Products as Modulators of Nrf2 Signaling Pathway in Neuroprotection

Neurodegenerative diseases (NDs) affect the West due to the increase in life expectancy. Nervous cells accumulate oxidative damage, which is one of the factors that triggers and accelerates neurodegeneration. However, cells have mechanisms that scavenge reactive oxygen species (ROS) and alleviate oxidative stress (OS). Many of these endogenous antioxidant systems are regulated at the gene expression level by the transcription factor Nrf2 (nuclear factor erythroid 2-related factor 2). In the presence of prooxidant conditions, Nrf2 translocates to the nucleus and induces the transcription of genes containing ARE (antioxidant response element). In recent years, there has been an increase in the study of the Nrf2 pathway and the natural products that positively regulate it to reduce oxidative damage to the nervous system, both in in vitro models with neurons and microglia subjected to stress factors and in vivo models using mainly murine models. Quercetin, curcumin, anthocyanins, tea polyphenols, and other less studied phenolic compounds such as kaempferol, hesperetin, and icariin can also modulate Nrf2 by regulating several Nrf2 upstream activators. Another group of phytochemical compounds that upregulate this pathway are terpenoids, including monoterpenes (aucubin, catapol), diterpenes (ginkgolides), triterpenes (ginsenosides), and carotenoids (astaxanthin, lycopene). This review aims to update the knowledge on the influence of secondary metabolites of health interest on the activation of the Nrf2 pathway and their potential as treatments for NDs.

Minocycline alleviated scopolamine-induced amnesia by regulating antioxidant and cholinergic function

Background and aim

Minocycline, a tetracycline derivative, has been found to exert neuroprotective properties. The current project aimed to assess the antioxidant status and cholinergic function in the amnesia induced by scopolamine.

Methods

We evaluated the passive avoidance performance, acetylcholine esterase (AChE) enzyme activity, and the oxidative stress indicators in the following groups: Normal control, scopolamine, and the treatment groups (the animals were given minocycline (10-30 mg/kg)).

Results

Scopolamine (intraperitoneal) injection was associated with impairment of passive avoidance performance and neurotoxicity. Minocycline pronouncedly ameliorated scopolamine injury as presented by the increased latency time to darkness and stay time in lightness along with the decreased darkness entry. Moreover, minocycline decreased lipid peroxidation, while it elevated the levels of superoxide dismutase, AChE enzymes, and thiol groups in both the cortex and hippocampus.

Conclusion

Our data suggested that minocycline modulated the antioxidant status and AChE in the brains, which may contribute to its protective effects against scopolamine-induced amnesia.

Ginsenoside ompound K reduces neuronal damage and improves neuronal synaptic dysfunction by targeting Aβ

Background: Alzheimer's disease (AD) is the most common neurodegenerative condition worldwide, with amyloid ß (Aβ) fibrils presenting as its main pathological feature. This study investigated whether Ginsenoside Compound K (CK) has activity against Aβ and its mechanism in reducing synaptic damage and cognitive impairment. Methods: The binding capacity of CK to Aβ42 and Nrf2/Keap1 was determined using molecular docking. Transmission electron microscopy was used to monitor CK-mediated degradation of Aβ fibrils. The effect of CK on the survival of Aβ42-damaged HT22 cells was determined using a CCK-8 assay. The therapeutic efficacy of CK in a scopoletin hydrobromide (SCOP) induced cognitive dysfunction mouse model was measured using a step-down passive avoidance test. GO enrichment analysis of mouse brain tissue was peformed using Genechip. Hydroxyl radical scavenging and reactive oxygen species assays were performed to verify the antioxidant activity of CK. The effects of CK on the expression of Aβ42, the Nrf2/Keap1 signaling pathway, and other proteins were determined by western blotting, immunofluorescence, and immunohistochemistry. Results: Molecular docking results showed that CK interacts with Lys16 and Glu3 of Aβ42. CK reduced the aggregation of Aβ42 as observed using transmission electron microscopy. CK increased the level of insulin-degrading enzyme and decreased the levels ß-secretase and γ-secretase; therefore, it can potentially inhibit the accumulation of Aβ in neuronal extracellular space in vivo. CK improved cognitive impairment and increased postsynaptic density protein 95 and synaptophysin expression levels in mice with SCOP-induced cognitive dysfunction. Further, CK inhibited the expression of cytochrome C, Caspase-3, and cleaved Caspase-3. Based on Genechip data, CK was found to regulate molecular functions such as oxygen binding, peroxidase activity, hemoglobin binding, and oxidoreductase activity, thus affecting the production of oxidative free radicals in neurons. Further, CK regulated the expression of the Nrf2/Keap1 signaling pathway through its interaction with the Nrf2/Keap1 complex. Conclusion: Our findings show that CK regulates the balance between Aβ monomers production and clearance, CK binds to Aβ monomer to inhibits the accumulation of Aβ, increases the level of Nrf2 in neuronal nuclei, reduces oxidative damage of neurons, improves synaptic function, thus ultimately protecting neurons.

Targeting the Nrf2 signaling pathway using phytochemical ingredients: A novel therapeutic road map to combat neurodegenerative diseases

BACKGROUND

Nuclear factor erythroid 2-related factor 2 (Nrf2) is a classical nuclear transcription factor that regulates the system's anti-oxidative stress response. The activation of Nrf2 induces the expression of antioxidant proteins and improves the system's anti-oxidative stress ability. Accumulating evidence suggests that Nrf2-centered signaling pathways may be a key pharmacological target for the treatment of neurodegenerative diseases (NDDs). However, phytochemicals as new therapeutic agents against NDDs have not been clearly delineated.

PURPOSE

To review the therapeutic effects of phytochemical ingredients on NDDs by activating Nrf2 and reducing oxidative stress injury.

METHODS

A comprehensive search of published articles was performed using various literature databases including PubMed, Google Scholar, and China National Knowledge Infrastructure. The search terms included "Nrf2", "phytochemical ingredients", "natural bioactive agents", "neurodegenerative diseases", "Antioxidant", "Alzheimer's disease", "Parkinson's disease", "Huntington's disease", "amyotrophic lateral sclerosis" "multiple sclerosis", "toxicity", and combinations of these keywords. A total of 769 preclinical studies were retrieved until August 2022, and we included 39 of these articless on phytochemistry, pharmacology, toxicology and other fields.

RESULTS

Numerous in vivo and in vitro studies showed that phytochemical ingredients could act as an Nrf2 activator in the treatment of NDDs through the antioxidant defense mechanism. These phytochemical ingredients, such as salidroside, naringenin, resveratrol, sesaminol, ellagic acid, ginsenoside Re, tanshinone I, sulforaphane, curcumin, naringin, tetramethylpyrazine, withametelin, magnolol, piperine, and myricetin, had the potential to improve Nrf2 signaling, thereby combatting NDDs.

CONCLUSION

As Nrf2 activators, phytochemical ingredients may provide a novel potential strategy for the treatment of NDDs. Here, we reviewed the interaction between phytochemical ingredients, Nrf2, and its antioxidant damaging pathway in NDDs and explored the advantages of phytochemical ingredients in anti-oxidative stress, which provides a reliable basis for improving the treatment of NDDs. However, further clinical trials are needed to determine the safety and efficacy of Nrf2 activators for NDDs.

Sweroside Ameliorated Memory Deficits in Scopolamine-Induced Zebrafish (Danio rerio) Model: Involvement of Cholinergic System and Brain Oxidative Stress

Sweroside is a secoiridoid glycoside and belongs to a large group of naturally occurring monoterpenes with glucose sugar attached to C-1 in the pyran ring. Sweroside can promote different biological activities such as antifungal, antibacterial, hepatoprotective, gastroprotective, sedative and antitumor, antioxidant, and neuroprotective activities. Zebrafish were given sweroside (12.79, 8.35, and 13.95 nM) by immersion once daily for 8 days, along with scopolamine (Sco, 100 μM) 30 min before the initiation of the behavioral testing to cause anxiety and memory loss. Employing the novel tank diving test (NTT), the Y-maze, and the novel object recognition test (NOR), anxiety-like reactions and memory-related behaviors were assessed. The following seven groups (n = 10 animals per group) were used: control, Sco (100 μM), sweroside treatment (2.79, 8.35, and 13.95 nM), galantamine (GAL, 2.71 μM as the positive control in Y-maze and NOR tests), and imipramine (IMP, 63.11 μM as the positive control in NTT test). Acetylcholinesterase activity (AChE) and the antioxidant condition of the brains were also evaluated. The structure of sweroside isolated from Schenkia spicata was identified. Treatment with sweroside significantly improved the Sco-induced decrease of the cholinergic system activity and brain oxidative stress. These results suggest that sweroside exerts a significant effect on anxiety and cognitive impairment, driven in part by the modulation of the cholinergic system activity and brain antioxidant action.

Current Progress on Neuroprotection Induced by Artemisia, Ginseng, Astragalus, and Ginkgo Traditional Chinese Medicines for the Therapy of Alzheimer's Disease

Aging is associated with the occurrence of diverse degenerative changes in various tissues and organs and with an increased incidence of neurological disorders, especially neurodegenerative diseases such as Alzheimer's disease (AD). In recent years, the search for effective components derived from medicinal plants in delaying aging and preventing and treating neurodegenerative diseases has been increasing and the number of related publications shows a rising trend. Here, we present a concise, updated review on the preclinical and clinical research progress in the assessment of the therapeutic potential of different traditional Chinese medicines and derived active ingredients and their effect on the signaling pathways involved in AD neuroprotection. Recognized by their multitargeting ability, these natural compounds hold great potential in developing novel drugs for AD.

Oxidative Stress and Ginsenosides: An Update on the Molecular Mechanisms

Ginsenosides are a class of active components extracted from ginseng plants (such as Panax ginseng, Panax quinquefolium, and Panax notoginseng). Ginsenosides have significant protective effects on the nervous system, cardiovascular system, and immune system, so they have been widely used in the treatment of related diseases. Entry of a variety of endogenous or exogenous harmful substances into the body can lead to an imbalance between the antioxidant defense system and reactive oxygen species, thus producing toxic effects on a variety of tissues and cells. In addition, oxidative stress can alter multiple signaling pathways, including the Keap1/Nrf2/ARE, PI3K/AKT, Wnt/β-catenin, and NF-κB pathways. With the deepening of research in this field, various ginsenoside monomers have been reported to exert antioxidant effects through multiple signaling pathways and thus have good application prospects. This article summarized the research advancements regarding the antioxidative effects and related mechanisms of ginsenosides, providing a theoretical basis for experimental research on and clinical treatment with ginsenosides.

Ginsenoside Compound K Enhances Fracture Healing via Promoting Osteogenesis and Angiogenesis

Fractures have an extraordinarily negative impact on an individual’s quality of life and functional status, particularly delayed or non-union fractures. Osteogenesis and angiogenesis are closely related to bone growth and regeneration, and bone modeling and remodeling. Recently Chinese medicine has been extensively studied to promote osteogenic differentiation in MSCs. Studies have found that Ginseng can be used as an alternative for tissue regeneration and engineering. Ginseng is a commonly used herbal medicine in clinical practice, and one of its components, Ginsenoside Compound K (CK), has received much attention. Evidence indicates that CK has health-promoting effects in inflammation, atherosclerosis, diabetics, aging, etc. But relatively little is known about its effect on bone regeneration and the underlying cellular and molecular mechanisms. In this study, CK was found to promote osteogenic differentiation of rat bone marrow mesenchymal stem cells (rBMSCs) by RT-PCR and Alizarin Red S staining in vitro. Mechanistically, we found CK could promote osteogenesis through activating Wnt/β-catenin signaling pathway by immunofluorescence staining and luciferase reporter assay. And we also showed that the tube formation capacity of human umbilical vein endothelial cells (HUVECs) was increased by CK. Furthermore, using the rat open femoral fracture model, we found that CK could improve fracture repair as demonstrated by Micro-CT, biomechanical and histology staining analysis. The formation of H type vessel in the fracture callus was also increased by CK. These findings provide a scientific basis for treating fractures with CK, which may expand its application in clinical practice.

Ginsenosides in central nervous system diseases: Pharmacological actions, mechanisms, and therapeutics

The nervous system is one of the most complex physiological systems, and central nervous system diseases (CNSDs) are serious diseases that affect human health. Ginseng (Panax L.), the root of Panax species, are famous Chinese herbs that have been used for various diseases in China, Japan, and Korea since ancient times, and remain a popular natural medicine used worldwide in modern times. Ginsenosides are the main active components of ginseng, and increasing evidence has demonstrated that ginsenosides can prevent CNSDs, including neurodegenerative diseases, memory and cognitive impairment, cerebral ischemia injury, depression, brain glioma, multiple sclerosis, which has been confirmed in numerous studies. Therefore, this review summarizes the potential pathways by which ginsenosides affect the pathogenesis of CNSDs mainly including antioxidant effects, anti-inflammatory effects, anti-apoptotic effects, and nerve protection, which provides novel ideas for the treatment of CNSDs.

The Effects of Ginsenosides on the Nrf2 Signaling Pathway

Nuclear factor erythroid-2 related factor 2 (Nrf2) is a major signaling pathway for the maintenance of homeostasis and redox balance. This pathway also plays a significant role in proteostasis, xenobiotic/drug metabolism, apoptosis, and lipid and carbohydrate metabolism. Conversely, the Nrf2 signaling pathway is impaired in several pathological conditions including cancer. Although various drugs have been developed to target the Nrf2 pathway, plant-derived chemicals than can potentially impact this pathway and are particularly attractive due to their minimal side effects. Ginsenosides are active components of ginseng and have been shown to exert pharmacological effects including antioxidant, anti-inflammatory, antitumor, antidiabetes, neuroprotective, and hepatoprotective activities. In this article, we have reviewed the effects of ginsenosides on Nrf2 signaling pathway.

Dietary uptake of Salvia macilenta extract improves Nrf2 antioxidant signaling pathway and diminishes inflammation and apoptosis in amyloid beta-induced rats

BACKGROUND

Studies showed the protective role of Salvia in traditional medicine against neurodegenerative diseases. Salvia macilenta is one of the potent antioxidant herbs among Salvia species against oxidative stress. In the current study, the effect of oral administration of S. macilenta in the antioxidant, anti-inflammatory activities of Aβ-injected male albino Wistar rats was determined.

METHODS

Rats were received S. macilenta (50 mg/kg/day) orally, for ten successive days and then some of them received Aβ (10 ng/µl) in their hippocampus (CA1 region). Proteins involved in antioxidant defense system and inflammatory signaling pathways in the hippocampus and prefrontal cortex were evaluated using Western blotting technique. To study apoptosis, Western blotting technique and histological staining were used. Catalase activity, glutathione peroxidase (GSH) and nitric oxide levels were measured.

RESULTS

Results demonstrated that S. macilenta increased Nrf2 protein level and decreased TNFα and IL-6 protein level in Aβ-injected rats compared to the Aβ-injected group in the hippocampus and prefrontal cortex. Histological analysis showed pretreatment with S. macilenta decreased apoptosis levels in the hippocampus and prefrontal cortex, about 41 and 42%, compared to Aβ-injected rats, respectively. This study showed that catalase activity was changed in the S. macilenta + Aβ group compared to the Aβ-injected rats. Also, GSH level was increased in the S. macilenta + Aβ group compared to the Aβ-injected rat.

CONCLUSION

Orally treatment of S. macilenta extract in Aβ-injected rats could ameliorate protective pathways and, so, it can be one of the proposed dietary supplements for the prevention of Alzheimer's disease and dementia.

Herb Sanqi-Derived Compound K Alleviates Oxidative Stress in Cultured Human Melanocytes and Improves Oxidative-Stress-Related Leukoderma in Guinea Pigs

Sanqi, a traditional Chinese herb, is widely used for cardiovascular diseases, and its neuroprotective effects against oxidative stress were recently discovered. The purpose of this study was to investigate whether Sanqi-derived compound K (Sanqi-CK), an active metabolite of Sanqi, could protect melanocytes from oxidative stress. Cultured human primary skin epidermal melanocytes (HEMn-MPs) were treated with hydrogen peroxide (H₂O₂) in the presence or absence of Sanqi-CK. Sanqi-CK exhibited protective effects against H₂O₂-induced cell death by reducing oxidative stress. In addition, treatment with Sanqi-CK reversed the decreased glutathione reductase activity and decreased ratio of reduced glutathione (GSH)/oxidized glutathione (GSSG) seen in H₂O₂-treated melanocytes. Furthermore, topical application of Sanqi-CK alleviated leukoderma in guinea pigs, a disorder characterized by melanocyte cell death resulting from rhododendrol-induced oxidative stress. Taken together, these data suggest that Sanqi-CK protects melanocytes against oxidative stress, and its protective effects are associated with modulating the redox balance between GSH and GSSG and activating glutathione reductase. Thus, Sanqi-CK may be a good candidate for preventing melanocyte loss in oxidative-stress-associated pigmentary disorders.

Neuroprotective Potentials of Panax Ginseng Against Alzheimer's Disease: A Review of Preclinical and Clinical Evidences

Alzheimer's disease (AD), a neurodegenerative disorder, is a major health concern in the increasingly aged population worldwide. Currently, no clinically effective drug can halt the progression of AD. Panax ginseng C.A. Mey. is a well-known medicinal plant that contains ginsenosides, gintonin, and other components and has neuroprotective effects against a series of pathological cascades in AD, including beta-amyloid formation, neuroinflammation, oxidative stress, and mitochondrial dysfunction. In this review, we summarize the effects and mechanisms of these major components and formulas containing P. ginseng in neuronal cells and animal models. Moreover, clinical findings regarding the prevention and treatment of AD with P. ginseng or its formulas are discussed. This review can provide new insights into the possible use of ginseng in the prevention and treatment of AD.

Evaluating the protective effects of individual or combined ginsenoside compound K and the downregulation of soluble epoxide hydrolase expression against sodium valproate-induced liver cell damage

Sodium valproate (SVP) is one of the most commonly prescribed antiepileptic drugs. However, SVP is known to induce hepatotoxicity, which limits its clinical application for treating various neurological disorders. Previously, we found that ginsenoside compound K (G-CK) demonstrated protective effects against SVP-induced hepatotoxicity by mitigating oxidative stress and mitochondrial damage, as well as downregulating the expression of soluble epoxide hydrolase (sEH) in rats. This study aimed to assess the effect of G-CK on SVP-induced cytotoxicity in human hepatocytes (L02 cell line), as well as the effect of the downregulation of sEH expression on both the hepatotoxicity of SVP and the hepatoprotective effects of G-CK. We observed that G-CK significantly ameliorated the decrease of cell viability, elevated ALT, AST and ALP activities, significant oxidative stress, and loss of mitochondrial membrane potential induced by SVP in L02 cells. G-CK also inhibited the SVP-mediated upregulation of sEH expression. Transfection of the L02 cells with siRNA-sEH led to a partial improvement in the L02 cytotoxicity caused by SVP by mitigating cellular oxidative stress without recovering the reduced mitochondrial membrane potential. Furthermore, the combination of siRNA-sEH and G-CK had better inhibitory effects on the SVP-induced changes of all detection indices except mitochondrial membrane potential than G-CK alone. Together, our results demonstrated that the combination of siRNA-sEH and G-CK better suppressed the SVP-induced cytotoxicity in L02 cells compared to either G-CK or siRNA-sEH alone.

Novel target for treating Alzheimer's Diseases: Crosstalk between the Nrf2 pathway and autophagy

In mammals, the Keap1-Nrf2-ARE pathway (henceforth, "the Nrf2 pathway") and autophagy are major intracellular defence systems that combat oxidative damage and maintain homeostasis. p62/SQSTM1, a ubiquitin-binding autophagy receptor protein, links the Nrf2 pathway and autophagy. Phosphorylation of p62 dramatically enhances its affinity for Keap1, which induces Keap1 to release Nrf2, and the p62-Keap1 heterodimer recruits LC3 and mediates the permanent degradation of Keap1 in the selective autophagy pathway. Eventually, Nrf2 accumulates in the cytoplasm and then translocates into the nucleus to activate the transcription of downstream genes that encode antioxidant enzymes, which protect cells from oxidative damage. Since Nrf2 also upregulates the expression of the p62 gene, a p62-Keap1-Nrf2 positive feedback loop is created that further enhances the protective effect on cells. Studies have shown that the p62-activated noncanonical Nrf2 pathway is an important marker of neurodegenerative diseases. The p62-Keap1-Nrf2 positive feedback loop and the Nrf2 pathway are involved in eliminating the ROS and protein aggregates induced by AD. Therefore, maintaining the homeostasis of the p62-Keap1-Nrf2 positive feedback loop, which is a bridge between the Nrf2 pathway and autophagy, may be a potential target for the treatment of AD.

Nrf2: a dark horse in Alzheimer's disease treatment

Alzheimer's disease (AD), an age-dependent neurodegenerative disorder, is the main cause of dementia. Common hallmarks of AD include the amyloid β-peptide (Aβ) aggregation, high levels of hyperphosphorylated tau protein (p-tau) and failure in redox homeostasis. To date, all proposed drugs affecting Aβ and/or p-tau have been failed in clinical trials. A decline in the expression of the transcription factor Nrf2 (nuclear factor-erythroid 2-p45 derived factor 2) and its driven genes (NQO1, HO-1, and GCLC), and alteration of the Nrf2-related pathways have been observed in AD brains. Nrf2 plays a critical role in maintaining cellular redox homeostasis and regulating inflammation response. Nrf2 activation also provides cytoprotection against increasing pathologies including neurodegenerative diseases. These lines of evidence imply that Nrf2 activation may be a novel AD treatment option. Interestingly, recent studies have also demonstrated that Nrf2 interferes with several key pathogenic processes in AD including Aβ and p-tau pathways. The current review aims to provide insights into the role of Nrf2 in AD. Also, we discuss the progress and challenges regarding the Nrf2 activators for AD treatment.

Chemical constituents of Panax ginseng and Panax notoginseng explain why they differ in therapeutic efficacy

Panax ginseng (Meyer) and Panax notoginseng (Burkill), belonging to the family Araliaceae, are used worldwide as medicinal and functional herbs. Numerous publications over the past decades have revealed that both P. notoginseng and P. ginseng contain important bioactive ingredients such as ginsenosides and exert multiple pharmacological effects on nervous system and immune diseases. However, based on traditional Chinese medicine (TCM) theory, their applications clearly differ as ginseng reinforces vital energy and notoginseng promotes blood circulation. In this article, we review the similarities and differences between ginseng and notoginseng in terms of their chemical composition and pharmacological effects. Their chemical comparisons indicate that ginseng contains more polysaccharides and amino acids, while notoginseng has more saponins, volatile oil, and polyacetylenes. Regarding pharmacological effects, ginseng exhibits better protective effects on cardiovascular disease, nerve disease, cancer, and diabetes mellitus, whereas notoginseng displays a superior protective effect on cerebrovascular disease. The evidence presented in this review facilitates further research and clinical applications of these two herbs, and exploration of the relationship between the chemical components and disease efficacy may be the critical next step.

Attenuation of Nrf2/Keap1/ARE in Alzheimer's Disease by Plant Secondary Metabolites: A Mechanistic Review

Alzheimer’s disease (AD) is a progressive neuronal/cognitional dysfunction, leading to disability and death. Despite advances in revealing the pathophysiological mechanisms behind AD, no effective treatment has yet been provided. It urges the need for finding novel multi-target agents in combating the complex dysregulated mechanisms in AD. Amongst the dysregulated pathophysiological pathways in AD, oxidative stress seems to play a critical role in the pathogenesis progression of AD, with a dominant role of nuclear factor erythroid 2-related factor 2 (Nrf2)/Kelch-like ECH-associated protein-1 (Keap1)/antioxidant responsive elements (ARE) pathway. In the present study, a comprehensive review was conducted using the existing electronic databases, including PubMed, Medline, Web of Science, and Scopus, as well as related articles in the field. Nrf2/Keap1/ARE has shown to be the upstream orchestrate of oxidative pathways, which also ameliorates various inflammatory and apoptotic pathways. So, developing multi-target agents with higher efficacy and lower side effects could pave the road in the prevention/management of AD. The plant kingdom is now a great source of natural secondary metabolites in targeting Nrf2/Keap1/ARE. Among natural entities, phenolic compounds, alkaloids, terpene/terpenoids, carotenoids, sulfur-compounds, as well as some other miscellaneous plant-derived compounds have shown promising future accordingly. Prevailing evidence has shown that activating Nrf2/ARE and downstream antioxidant enzymes, as well as inhibiting Keap1 could play hopeful roles in overcoming AD. The current review highlights the neuroprotective effects of plant secondary metabolites through targeting Nrf2/Keap1/ARE and downstream interconnected mediators in combating AD.

Ginsenoside Compound K: Insights into Recent Studies on Pharmacokinetics and Health-Promoting Activities

Ginseng (Panax ginseng) is an herb popular for its medicinal and health properties. Compound K (CK) is a secondary ginsenoside biotransformed from major ginsenosides. Compound K is more bioavailable and soluble than its parent ginsenosides and hence of immense importance. The review summarizes health-promoting in vitro and in vivo studies of CK between 2015 and 2020, including hepatoprotective, anti-inflammatory, anti-atherosclerosis, anti-diabetic, anti-cancer, neuroprotective, anti-aging/skin protective, and others. Clinical trial data are minimal and are primarily based on CK-rich fermented ginseng. Besides, numerous preclinical and clinical studies indicating the pharmacokinetic behavior of CK, its parent compound (Rb1), and processed ginseng extracts are also summarized. With the limited evidence available from animal and clinical studies, it can be stated that CK is safe and well-tolerated. However, lower water solubility, membrane permeability, and efflux significantly diminish the efficacy of CK and restrict its clinical application. We found that the use of nanocarriers and cyclodextrin for CK delivery could overcome these limitations as well as improve the health benefits associated with them. However, these derivatives have not been clinically evaluated, thus requiring a safety assessment for human therapy application. Future studies should be aimed at investigating clinical evidence of CK.

Effects of compound K, a metabolite of ginsenosides, on memory and cognitive dysfunction in db/db mice involve the inhibition of ER stress and the NLRP3 inflammasome pathway

Accumulating clinical and epidemiological evidence indicates a close relationship between diabetes mellitus and dementia. The ginsenoside compound K (CK) has been reported to ameliorate diabetes mellitus and confer protection to the central nervous system. In this study, we investigated whether CK could improve memory impairment and cognitive dysfunction in diabetic db/db mice. Firstly, we found that CK treatments significantly improved behavioral impairment and cognitive dysfunction based on Morris water maze, Y-maze, and fear conditioning tests. Besides, CK decreased the fasting glucose level, increased lipid metabolism, and ameliorated glucose tolerance, insulin sensitivity, and dyslipidemia in diabetic db/db mice. In addition, CK treatments alleviated oxidative stress and inhibited the inflammatory response in hippocampal tissue. Further investigations showed that CK treatments inhibited the NLRP3 inflammasome pathway, as evidenced by the declined expression of TXNIP, NLRP3 inflammasomes, ASC, cleaved caspase-1, and mature IL-1β in hippocampal tissues. Moreover, CK treatments alleviated ER stress via down-regulating the level of BiP, CHOP, p-PERK, p-IRE1α and ATF6 in the hippocampus of db/db mice. These results suggest that CK improves memory and cognitive dysfunction, possibly by ameliorating glucose tolerance, insulin sensitivity, and dyslipidemia, suppressing oxidative stress and inflammatory response and modulating the NLRP3 inflammasome pathway and ER stress.

QTC-4-MeOBnE Rescues Scopolamine-Induced Memory Deficits in Mice by Targeting Oxidative Stress, Neuronal Plasticity, and Apoptosis

Cognitive decline and memory impairment induced by disruption of cholinergic neurons and oxidative brain damage are among the earliest pathological hallmark signatures of Alzheimer's disease. Scopolamine is a postsynaptic muscarinic receptor blocker which causes impairment of cholinergic transmission resulting in cognitive deficits. Herein we investigated the effect of QTC-4-MeOBnE (1-(7-chloroquinolin-4-yl)-N-(4-methoxybenzyl)-5-methyl-1H-1,2,3-triazole-4-carboxamide) on memory impairments in mice chronically treated with scopolamine and the molecular mechanisms involved. Administration of scopolamine (1 mg/kg) for 15 days resulted in significant impairments in working and short-term memory in mice, as assessed by the novel object recognition and the Y-maze paradigms. However, both deficits were prevented if mice receiving the scopolamine were also treated with QTC-4-MeOBnE. This effect was associated with an increase in antioxidant enzymes (superoxide dismutase and catalase), a reduction in lipid peroxidation, and an increase in Nrf2 expression. Moreover, brains from QTC-4-MeOBnE treated mice had a significant decrease in acetylcholinesterase activity and glycogen synthase kinase-3β levels but an increase in brain-derived neurotrophic factor and Bcl-2 expression levels. Taken together our findings demonstrate that the beneficial effect of QTC-4-MeOBnE in a mouse model of scopolamine-induced memory impairment is mediated via the involvement of different molecular pathways including oxidative stress, neuroplasticity, neuronal vulnerability, and apoptosis. Our study provides further evidence on the promising therapeutic potential of QTC-4-MeOBnE as a multifactorial disease modifying drug in AD and related dementing disorders.

Non-polyphenolic natural inhibitors of amyloid aggregation

Protein misfolding diseases (PMDs) are chronic and progressive, with no effective therapy so far. Aggregation and misfolding of amyloidogenic proteins are closely associated with the onset and progression of PMDs, such as amyloid-β (Aβ) in Alzheimer's disease, α-Synuclein (α-Syn) in Parkinson's disease and human islet amyloid polypeptide (hIAPP) in type 2 diabetes. Inhibiting toxic aggregation of amyloidogenic proteins is regarded as a promising therapeutic approach in PMDs. The past decade has witnessed the rapid progresses of this field, dozens of inhibitors have been screened and verified in vitro and in vivo, demonstrating inhibitory effects against the aggregation and misfolding of amyloidogenic proteins, together with beneficial effects. Natural products are major sources of small molecule amyloid inhibitors, a number of natural derived compounds have been identified with great bioactivities and translational prospects. Here, we review the non-polyphenolic natural inhibitors that potentially applicable for PMDs treatment, along with their working mechanisms. Future directions are proposed for the development and clinical applications of these inhibitors.

Ginsenoside protects against AKI via activation of HIF‑1α and VEGF‑A in the kidney‑brain axis

Acute kidney injury (AKI) is characterized by abrupt kidney dysfunction. It results in remote organ dysfunction, including the brain. The underlying mechanism of the kidney‑brain axis in AKI and effective protective approaches remain unknown. The present study aimed to investigate the potential protective effect of ginsenoside (GS) on AKI induced by glycerol in rats. Kidney function was initially assessed by blood urea nitrogen (BUN) and creatinine (Cre) tests, and was identified to be severely impaired following glycerol treatment, based on significant increases in BUN and Cre levels observed. Severe extensive necrosis of the majority of the renal tubules was observed by hematoxylin and eosin staining, additionally confirming that glycerol induced AKI. GS was identified to ameliorate the impairment of kidney function in the context of AKI. Further investigation of the mechanism revealed that GS may induce protection against oxidative stress via a kidney‑brain axis. Furthermore, GS improved the activation of hypoxia‑inducible factor 1α (HIF‑1α) and vascular endothelial growth factor A (VEGF‑A) in the hypothalamus response to AKI, and in the kidney tissues. The protective effect of GS in AKI may be associated with the interaction between the kidney and the brain. Taken together, these results suggested that GS was involved in the protective effects against AKI by decreasing oxidative damage to the kidney and brain, and by upregulating HIF‑1α and VEGF‑A levels in the kidney‑brain axis.

Molecular Mechanism of Autophagy: Its Role in the Therapy of Alzheimer's Disease

Alzheimer's disease (AD) is a neurodegenerative disorder of progressive dementia that is characterized by the accumulation of beta-amyloid (Aβ)-containing neuritic plaques and intracellular Tau protein tangles. This distinctive pathology indicates that the protein quality control is compromised in AD. Autophagy functions as a "neuronal housekeeper" that eliminates aberrant protein aggregates by wrapping then into autophagosomes and delivering them to lysosomes for degradation. Several studies have suggested that autophagy deficits in autophagy participate in the accumulation and propagation of misfolded proteins (including Aβ and Tau). In this review, we summarize current knowledge of autophagy in the pathogenesis of AD, as well as some pathways targeting the restoration of autophagy. Moreover, we discuss how these aspects can contribute to the development of disease-modifying therapies in AD.

Ginsenoside compound K alleviates sodium valproate-induced hepatotoxicity in rats via antioxidant effect, regulation of peroxisome pathway and iron homeostasis

Sodium valproate (SVP) is a first-line treatment for various forms of epilepsy; however, it can cause severe liver injury. Ginsenoside compound K (G-CK) is the main active ingredient of the traditional herbal medicine ginseng. According to our previous research, SVP-induced elevation of ALT and AST levels, as well as pathological changes of liver tissue, was believed to be significantly reversed by G-CK in LiCl-pilocarpine induced epileptic rats. Thus, we aimed to evaluate the protective effect of G-CK on hepatotoxicity caused by SVP. The rats treated with SVP showed liver injury with evident increases in hepatic index, transaminases activity, alkaline phosphatase level, hepatic triglyceride and lipid peroxidation; significant decreases in plasma albumin level and antioxidant capacity; and obvious changes in histopathological and subcellular structures. All of these changes could be mitigated by co-administration with G-CK. Proteomic analysis indicated that hepcidin, soluble epoxide hydrolase (sEH, UniProt ID P80299), and the peroxisome pathway were involved in the hepatoprotective effect of G-CK. Changes in protein expression of hepcidin and sEH were verified by ELISA and Western blot analysis, respectively. In addition, we observed that the hepatic iron rose in SVP group and decreased in the combination group. In summary, our findings demonstrate the clear hepatoprotective effect of G-CK against SVP-induced hepatotoxicity through the antioxidant effect, regulation of peroxisome pathway relying on sEH (P80299) downregulation, as well as regulation of iron homeostasis dependent on hepcidin upregulation.

Ginseng berry aqueous extract prevents scopolamine-induced memory impairment in mice

Ginseng berry exhibits a diverse range of pharmacological activities. The present study aimed to examine the neuroprotective effects of ginseng berry aqueous extract (GBE) against oxidative stress and to assess the impact of GBE on memory impairment in mice. In HT-22 cells, GBE pretreatment significantly inhibited glutamate- and hydrogen peroxide-mediated cytotoxicity in a concentration-dependent manner, while treatment with up to 100 µg/ml GBE alone did not change cell viability. In a murine model of scopolamine (SCP)-induced memory impairment, results from the passive avoidance test and the Morris water maze test indicated that GBE administration for 4 weeks prolonged step-through latency time and shortened escape latency time, suggesting that GBE can attenuate deficits in long-term memory induced by SCP. Additionally, GBE prevented SCP-induced reductions in acetylcholine by decreasing acetylcholinesterase activity and upregulating choline acetyltransferase mRNA levels in the hippocampus. GBE mitigated SCP-mediated mRNA decreases in brain-derived neurotrophic factor levels and its associated signaling molecules. Furthermore, GBE administration significantly suppressed malondialdehyde production and increased glutathione levels, catalase activity and superoxide dismutase activity in SCP-induced memory impaired mice. Therefore, the results of the current study indicated that ginseng berry may be a potential candidate for treating or preventing memory deficits that are associated with neurodegenerative disorders.

Ginsenoside compound K ameliorates Alzheimer's disease in HT22 cells by adjusting energy metabolism

Energy metabolism disorders have been shown to exert detrimental effects on the pathology of Alzheimer's disease (AD). The ginsenoside compound K (CK), a major intestinal metabolite underlying the pharmacological actions of orally administered ginseng, has an ameliorating effect against AD, but the relevant molecular mechanism remains unclear. We hypothesized that the improvement of AD by CK is mediated by the energy metabolism signaling pathway induced by amyloid β peptide (Aβ) and tested this hypothesis in HT22 cells. HT22 cells were incubated with CK and exposed to Aβ. Cell viability was analyzed using the MTT assay. Cell growth curves were derived from real-time cell analysis. Apoptosis was determined by flow cytometry, Aβ localization and expression by immunofluorescence, and ATP content by a specific assay kit. The expression of proteins related to the energy metabolism signaling pathway was analyzed using Western blotting. CK treatment improved cell viability, cell growth, and apoptosis induced by Aβ, and the cellular localization and expression of Aβ. Moreover, CK increased ATP content by promoting the activity of glucose transporters (GLUTs). Therefore, the neuroprotective effect of CK against Aβ injury was mainly realized through the activation of the energy metabolism signaling pathway. CK treatment inhibits neuronal damage caused by Aβ through the activation of the energy metabolism signaling pathway, revealing that CK might be one of the key bioactive ingredients of ginseng in the treatment of Alzheimer's disease and may serve as a preventive or therapeutic agent for Alzheimer's disease.

Natural Products in Alzheimer's Disease Therapy: Would Old Therapeutic Approaches Fix the Broken Promise of Modern Medicines?

Despite extensive progress in understanding the pathology of Alzheimer's disease (AD) over the last 50 years, clinical trials based on the amyloid-beta (Aβ) hypothesis have kept failing in late stage human trials. As a result, just four old drugs of limited clinical outcomes and numerous side effects are currently used for AD therapy. This article assesses the common pharmacological targets and therapeutic principles for current and future drugs. It also underlines the merits of natural products acting through a polytherapeutic approach over a monotherapy option of AD therapy. Multi-targeting approaches through general antioxidant and anti-inflammatory mechanisms coupled with specific receptor and/or enzyme-mediated effects in neuroprotection, neuroregeneration, and other rational perspectives of novel drug discovery are emphasized.

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.