Platycodin D Inhibits β-Amyloid-Induced Inflammation and Oxidative Stress in BV-2 Cells Via Suppressing TLR4/NF-κB Signaling Pathway and Activating Nrf2/HO-1 Signaling Pathway

Sequential system based on ferritin delivery system and cell therapy for modulating the pathological microenvironment and promoting recovery

The vicious crosstalk among capillarization of hepatic sinusoidal endothelial cells (LSECs), activation of hepatic stellate cells (aHSCs), and hepatocyte damage poses a significant impediment to the successful treatment of liver fibrosis. In this study, we propose a sequential combination therapy aimed at disrupting the malignant crosstalk and reshaping the benign microenvironment while repairing damaged hepatocytes to achieve effective treatment of liver fibrosis. Firstly, H-subunit apoferrin (Ferritin) was adopted to load platycodonin D (PLD) and MnO2, forming ferritin@MnO2/PLD (FMP) nanoparticles, which exploited the high affinity of ferritin for the highly expressed transferrin receptor 1 (TfR1) to achieve the precise targeted delivery of FMP in the liver. Upon PLD intervention, restoration of the fenestration pores in capillarized LSECs was facilitated by modulating the phosphatidyl inositol 3-kinase/protein kinase B (PI3K/AKT) and Kruppel Like Factor 2 (KLF2) signaling pathways both in vitro and in vivo, enabling efficient entry of FMP into the Disse space. Subsequently, FMP NPs effectively inhibited HSC activation by modulating the TLR2/TLR4/NF-κB-p65 signaling pathway. Moreover, FMP NPs efficiently scavenged reactive oxygen species (ROS) and mitigated the expression of inflammatory mediators, thereby reshaping the microenvironment to support hepatocyte repair. Finally, administration of bone marrow mesenchymal stem cells (BMMSCs) was employed to promote the regeneration and functional recovery of damaged hepatocytes. In conclusion, the combined sequential therapy involving FMP and BMMSCs effectively attenuated liver fibrosis induced by CCl4 administration, resulting in significant amelioration of the fibrotic condition. The therapeutic strategy outlined in this study underscores the significance of disrupting the deleterious cellular interactions and remodeling the microenvironment, thereby presenting a promising avenue for clinical intervention in liver fibrosis.

Platycodin D and voluntary running synergistically ameliorate memory deficits in 5 × FAD mice via mediating neuromodulation and neuroinflammation

Introduction

Alzheimer's disease (AD) is the leading cause of dementia, and currently, no effective treatments are available to reverse or halt its progression in clinical practice. Although a plethora of studies have highlighted the benefits of physical exercise in combating AD, elder individuals often have limited exercise capacity. Therefore, mild physical exercise and nutritional interventions represent potential strategies for preventing and mitigating neurodegenerative diseases. Our research, along with other studies, have demonstrated that platycodin D (PD) or its metabolite, platycodigenin, derived from the medicinal plant Platycodon grandiflorus, exerts neuroprotective effects against amyloid β (Aβ)-induced neuroinflammation. However, the combined effects of PD and physical exercise on alleviating AD have yet to be explored. The current study aimed to investigate whether combined therapy could synergistically ameliorate memory deficits and AD pathology in 5 × FAD mice.

Methods

Five-month-old 5 × FAD mice were randomly assigned to four groups, and received either PD (5 mg/kg/day, p.o.), voluntary running, or a combination of both for 47 days. Nest building test, locomotion test, and Morris water maze test were used to evaluate the cognitive function. Immunohistochemical and ELISA analysis was performed to determine Aβ build-up, microglia and astrocytes hyperactivation, and survival neurons in the hippocampus and perirhinal cortex. Real-time quantitative PCR analysis was used to assess the polarization of microglia and astrocytes. HPLC analysis was performed to measure monoamine neurotransmitters in the hippocampus.

Results and discussion

The combination of PD and voluntary running synergistically restored nest-building behavior, alleviated recognition and spatial memory deficits, and showed superior effects compared to monotherapy. In addition, the PD and voluntary running combination reduced Aβ build-up, decreased hyperactivation of microglia and astrocytes in the hippocampus and perirhinal cortex, promoted the polarization of inflammatory M1 microglia and reactive astrocytes toward beneficial phenotypes, and lowered systemic circulating pro-inflammatory cytokines while increasing anti-inflammatory cytokines in 5 × FAD mice. Furthermore, combined therapy effectively protected neurons and increased levels of 5-hydroxytryptamine (5-HT) and dopamine (DA) in the hippocampus of 5 × FAD mice. In conclusion, the combination of PD and voluntary running holds great potential as a treatment for AD, offering promise for delaying onset or progression of AD.

Platycodon grandiflorum exhibits anti-neuroinflammatory potential against beta-amyloid-induced toxicity in microglia cells

Background/objectives

Platycodon grandiflorum (PG) is used in traditional oriental medicine to treat several ailments.

Methods

The study investigated the anti-inflammatory and neuroprotective effects of PGW (P. grandiflorum) extract in Aβ25-35-induced inflammation in BV2 microglia cells.

Result

PGW demonstrated significant inhibition of nitric oxide (NO) production, with reductions of 30.4, 36.7, and 61.2% at concentrations of 50, 100, and 200 μg/mL, respectively. Moreover, PGW effectively suppressed the production of pro-inflammatory cytokines IL-1β and IL-6 and exhibited significant inhibitory activity against TNF-α at 200 μg/mL. Furthermore, PGW treatment mitigated apoptosis in Aβ-induced BV2 cells by modulating the mitochondrial apoptosis pathway, regulating Bcl-2 family protein synthesis, and inhibiting caspase activation. Mechanistically, PGW attenuated the activation of the MAPK (JNK, ERK, p38) pathway induced by Aβ, showing a concentration-dependent decrease in phosphorylation levels of these proteins. Additionally, PGW inhibited the NF-κB pathway activation by reducing the phosphorylation levels of p65 and IκBα in a concentration-dependent manner.

Conclusion

PGW demonstrated anti-inflammatory and neuroprotective effects in Aβ-induced neuronal cells, suggesting its potential as a therapeutic agent for neuroinflammatory associated with neurodegenerative diseases.

Platycodon grandiflorum root extract inhibits Aβ deposition by breaking the vicious circle linking oxidative stress and neuroinflammation in Alzheimer's disease

Alzheimer's disease (AD) is a progressive neurodegenerative disease accompanied by irreversible cognitive impairment. A deleterious feedback loop between oxidative stress and neuroinflammation in early AD exacerbates AD-related pathology. Platycodon grandiflorum root extract (PGE) has antioxidant and anti-inflammatory effects in several organs. However, the mechanisms underlying the effects of PGE in the brain remain unclear, particularly regarding its impact on oxidative/inflammatory damage and Aβ deposition. Thus, we aim to identify the mechanism through which PGE inhibits Aβ deposition and oxidative stress in the brain by conducting biochemical and histological analyses. First, to explore the antioxidant mechanism of PGE in the brain, we induced oxidative stress in mice injected with scopolamine and investigated the effect of PGE on cognitive decline and oxidative damage. We also assessed the effect of PGE on reactive oxygen species (ROS) generation and the expressions of antioxidant enzymes and neurotrophic factor in H2O2- and Aβ-treated HT22 hippocampal cells. Next, we investigated whether PGE, which showed antioxidant effects, could reduce Aβ deposition by mitigating neuroinflammation, especially microglial phagocytosis. We directly verified the effect of PGE on microglial phagocytosis, microglial activation markers, and pro-inflammatory cytokines in Aβ-treated BV2 microglial cells. Moreover, we examined the effect of PGE on neuroinflammation, inducing microglial responses in Aβ-overexpressing 5XFAD transgenic mice. PGE exerts antioxidant effects in the brain, enhances microglial phagocytosis of Aβ, and inhibits neuroinflammation and Aβ deposition, ultimately preventing neuronal cell death in AD. Taken together, our findings indicate that the therapeutic potential of PGE in AD is mediated by its targeting of multiple pathological processes.

Biotransformation and pharmacological activities of platycosides from Platycodon grandiflorum roots

In Northeast China, Goubao pickle is a popular food fermented from the roots of Platycodon grandiflorum as the main material, offering a unique flavor and rich nutritional value. Platycosides in roots of P. grandiflorum may play a crucial role in determining the quality of Goubao pickle through microorganism fermentation. However, biotransfermation of platycosides has not been reviewed during fermentation. In this study, we reviewed platycosides in chemical diversity, metabolic processes in vivo, biotransformation of platycosides in vitro, and pharmacological effects. Finally, we also discussed how to improve the bioactive secondary platycosides we desire by regulating enzymes from microorganisms in the future.

Platycodin D Ameliorates Cognitive Impairment in Type 2 Diabetes Mellitus Mice via Regulating PI3K/Akt/GSK3β Signaling Pathway

Objectives: The aim of this study was to investigate the ameliorative effect of platycodin D (PD) on cognitive dysfunction in type 2 diabetes mellitus (T2DM) and its potential molecular mechanisms of action in vivo and in vitro. Materials and methods: An animal model of cognitive impairment in T2DM was established using a single intraperitoneal injection of streptozotocin (100 mg/kg) after 8 weeks of feeding a high-fat diet to C57BL/6 mice. In vitro, immunofluorescence staining and Western blot were employed to analyze the effects of PD on glucose-induced neurotoxicity in mouse hippocampal neuronal cells (HT22). Results: PD (2.5 mg/kg) treatment for 4 weeks significantly suppressed the rise in fasting blood glucose in T2DM mice, improved insulin secretion deficiency, and reversed abnormalities in serum triglyceride, cholesterol, low-density lipoprotein, and high-density lipoprotein levels. Meanwhile, PD ameliorated choline dysfunction in T2DM mice and inhibited the production of oxidative stress and apoptosis-related proteins of the caspase family. Notably, PD dose-dependently prevents the loss of mitochondrial membrane potential, promotes phosphorylation of phosphatidylinositol 3 kinase and protein kinase B (Akt) in vitro, activates glycogen synthase kinase 3β (GSK3β) expression at the Ser9 site, and inhibits Tau protein hyperphosphorylation. Conclusions: These findings clearly indicated that PD could alleviate the neurological damage caused by T2DM, and the phosphorylation of Akt at Ser473 may be the key to its effect.

Interpreting the Mechanism of Active Ingredients in Polygonati Rhizoma in Treating Depression by Combining Systemic Pharmacology and In Vitro Experiments

Polygonati Rhizoma (PR) has certain neuroprotective effects as a homology of medicine and food. In this study, systematic pharmacology, molecular docking, and in vitro experiments were integrated to verify the antidepressant active ingredients in PR and their mechanisms. A total of seven compounds in PR were found to be associated with 45 targets of depression. Preliminarily, DFV docking with cyclooxygenase 2 (COX2) showed good affinity. In vitro, DFV inhibited lipopolysaccharide (LPS)-induced inflammation of BV-2 cells, reversed amoeba-like morphological changes, and increased mitochondrial membrane potential. DFV reversed the malondialdehyde (MDA) overexpression and superoxide dismutase (SOD) expression inhibition in LPS-induced BV-2 cells and decreased interleukin-1β (IL-1β), tumor necrosis factor-α (TNF-α), and IL-6 mRNA expression levels in a dose-dependent manner. DFV inhibited both mRNA and protein expression levels of COX2 induced by LPS, and the activation of NACHT, LRR, and PYD domains-containing protein 3 (NLRP3) and caspase1 was suppressed, thus exerting an antidepressant effect. This study proves that DFV may be an important component basis for PR to play an antidepressant role.

Platycodon D protects human nasal epithelial cells from pyroptosis through the Nrf2/HO-1/ROS signaling cascade in chronic rhinosinusitis

BACKGROUND

Pyroptosis has been demonstrated being closely associated with the inflammatory progression in chronic rhinosinusitis (CRS). However, platycodon D (PLD) has emerged as a key anti-inflammatory mediator in the inflammatory progression of various respiratory diseases. This study aims at investigating whether PLD could reduce inflammatory progression of CRS by inhibiting pyroptosis.

METHODS

Nasal mucosal tissues from patients with CRS and the control group (simple nasal septal deviation) were analyzed for morphological difference using hematoxylin & eosin staining and for the expression of pyroptosis-related makers by immunofluorescence (IF). Human nasal epithelial cells (HNEpCs) were cultured and co-stimulated with lipopolysaccharide (LPS)/adenosine triphosphate (ATP) to construct an in vitro cellular model simulating CRS. After pretreatment with PLD, EthD-I staining, TUNEL staining, transmission electron microscopy (TEM), and GSDMD-NT detection were performed to evaluate pyroptosis markers. The NLRP3 inflammasome was detected by IF and western blotting (WB). Reactive oxygen species (ROS) were detected by H2DCFDA staining, and mitochondrial membrane potential was evaluated by JC-1 staining. Mitochondrial morphology and structure were observed using TEM. The Nrf2/HO-1 antioxidant signaling pathway was detected using WB.

RESULTS

The nasal mucosa structure of patients with CRS exhibited significant damage, with a marked increase in the expression of pyroptosis-related proteins compared with the control group. LPS/ATP co-stimulation resulted in an increased expression of IL-18 and IL-1β in HNEpCs, causing significant damage to nuclear and cell membranes, GSDMD-NT accumulation around the cell membrane, and intracellular NLRP3 inflammasome activation. Furthermore, it led to increased ROS expression, significantly decreased mitochondrial membrane potential, and damaged mitochondrial structure. However, pretreatment with PLD significantly reversed the aforementioned trends and activated the Nrf2/HO-1 antioxidant signaling pathway.

CONCLUSIONS

The results of this study confirm that NLRP3-mediated pyroptosis plays a crucial role in the pathological process of nasal mucosal impairment in patients with CRS. PLD inhibits NLRP3-mediated pyroptosis, preventing inflammatory damage in HNEpCs of patients with CRS by activating the Nrf2/HO-1 antioxidant signaling pathway, which in turn reduces ROS production and ameliorates mitochondrial damage.

Triptolide activates the Nrf2 signaling pathway and inhibits the NF-κB signaling pathway to improve Alzheimer disease

Alzheimer disease (AD) is a common neurodegenerative disease with pathological features of accumulated amyloid plaques, neurofibrillary tangles, and the significant inflammatory environment. These features modify the living microenvironment for nerve cells, causing the damage, dysfunction, and death. Progressive neuronal loss directly leads to cognitive decline in AD patients and is closely related to brain inflammation. Therefore, impairing inflammation via signaling pathways may facilitate either the prevention or delay of the degenerative process. Triptolide has been evidenced to possess potent anti-inflammatory effect. In this review, we elaborate on two signaling pathways (the NF-κB and Nrf2 signaling pathways) that are involved in the anti-inflammatory effect of triptolide.

Platycodin D inhibits glioblastoma cell proliferation, migration, and invasion by regulating DEPDC1B-mediated epithelial-to-mesenchymal transition

BACKGROUND

Platycodin D (PD) is a potent bioactive constituent in the medicinal herb Platycodon grandiflorum. It has shown anticancer properties, particularly against glioblastoma (GB) and other human malignancies. DEPDC1B (DEP domain-containing protein 1B) is an oncogene associated with epithelial-mesenchymal transition (EMT). It is highly expressed in GB and correlated with tumor grade and patient prognosis. In this study, we investigated whether the antiglioma effect of PD was associated with downregulation of DEPDC1B.

METHODS

Gene expression and clinical data were obtained from the China Glioma Genome Atlas and The Cancer Genome Atlas databases for glioma samples. In vitro experiments were conducted using Cell Counting Kit-8 and Transwell assays to assess the impact of PD on the proliferation, migration, and invasion of GB cells. mRNA and protein expression was evaluated using real-time polymerase chain reaction and western blotting, respectively.

RESULTS

PD exerted inhibitory effects on the proliferation and motility of GB cells. PD downregulated DEPDC1B protein as well as several markers associated with EMT, namely N-cadherin, vimentin, and Snail. The suppressive effects of PD were enhanced when DEPDC1B was knocked down in GB cells, while overexpression of DEPDC1B in cells reversed the inhibitory effects of PD.

CONCLUSION

PD exerts an antiglioma effect by regulating DEPDC1B-mediated EMT.

NF-κB Pathway and Its Inhibitors: A Promising Frontier in the Management of Alzheimer's Disease

The nuclear factor kappa B (NF-κB) pathway has emerged as a pivotal player in the pathogenesis of various diseases, including neurodegenerative illnesses like Alzheimer's disease (AD). The involvement of the NF-κB pathway in immune system responses, inflammation, oxidative stress, and neuronal survival highlights its significance in AD progression. We discuss the advantages of NF-κB pathway inhibition, including the potential to mitigate neuroinflammation, modulate amyloid beta (Aβ) production, and promote neuronal survival. However, we also acknowledge the limitations and challenges associated with this approach. Balancing the fine line between dampening inflammation and preserving physiological immune responses is critical to avoid unintended consequences. This review combines current knowledge on the NF-κB pathway's intricate involvement in AD pathogenesis, emphasizing its potential as a therapeutic target. By evaluating both advantages and limitations, we provide a holistic view of the feasibility and challenges of NF-κB pathway modulation in AD treatment. As the quest for effective AD therapies continues, an in-depth understanding of the NF-κB pathway's multifaceted roles will guide the development of targeted interventions with the potential to improve AD management.

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.

Platycodin D induces proliferation inhibition and mitochondrial apoptosis in diffuse large B-cell lymphoma

Patients with diffuse large B-cell lymphoma (DLBCL) have unsatisfactory outcomes especially when relapse occurs after initial chemotherapy. Platycodin D (PD), a triterpenoid saponin isolated from the root of Platycodon grandiflorum (Jacq.) A. DC., has demonstrated potent anti-cancer activities. So far, however, information regarding the effect of PD on malignant lymphoma remains unavailable. In the present study, we showed that PD dose-dependently inhibited the viability of a serial of established DLBCL cell lines representing different molecular subtypes, and their sensitivities to PD were comparable. Mitochondrial dysfunction and subsequent intrinsic apoptosis were induced by PD, as indicated by the loss of mitochondrial membrane potential and the increase in the percentage of Annexin Ⅴ positive cells. Mechanistically, PD treatment downregulated expression levels of anti-apoptotic proteins including MCL-1, BCL-2, and BCL-XL, while upregulated the expression level of pro-apoptotic protein BAK, followed by the cleavage of PARP. Moreover, PD synergistically enhanced the cytotoxicity of BCL-2 inhibitor venetoclax. In a SUDHL-4-derived xenograft mouse model, PD administration significantly constrained the tumor growth without obvious side effects. Therefore, our results provided new insights into the role of PD in lymphoma therapy.

The pharmacology and mechanisms of platycodin D, an active triterpenoid saponin from Platycodon grandiflorus

Chinese doctors widely prescribed Platycodon grandiflorus A. DC. (PG) to treat lung carbuncles in ancient China. Modern clinical experiences have demonstrated that PG plays a crucial role in treating chronic pharyngitis, plum pneumonia, pneumoconiosis, acute and chronic laryngitis, and so forth. Additionally, PG is a food with a long history in China, Japan, and Korea. Furthermore, Platycodin D (PLD), an oleanane-type triterpenoid saponin, is one of the active substances in PG. PLD has been revealed to have anti-inflammatory, anti-viral, anti-oxidation, anti-obesity, anticoagulant, spermicidal, anti-tumor etc., activities. And the mechanism of the effects draws lots of attention, with various signaling pathways involved in these processes. Additionally, research on PLD's pharmacokinetics and extraction processes is under study. The bioavailability of PLD could be improved by being prescribed with Glycyrrhiza uralensis Fisch. or by creating a new dosage form. PLD has been recently considered to have the potential to be a solubilizer or an immunologic adjuvant. Meanwhile, PLD was discovered to have hemolytic activity correlated. PLD has broad application prospects and reveals practical pharmacological activities in pre-clinical research. The authors believe that these activities of PLD contribute to the efficacy of PG. What is apparent is that the clinical translation of PLD still has a long way to go. With the help of modern technology, the scope of clinical applications of PLD is probable to be expanded from traditional applications to new fields.

Hesperidin methylchalcone (HMC) hinders amyloid-β induced Alzheimer's disease by attenuating cholinesterase activity, macromolecular damages, oxidative stress and apoptosis via regulating NF-κB and Nrf2/HO-1 pathways

Phytocompounds therapy has recently emerged as an effective strategy to treat Alzheimer's disease. Herein, the protective effect of hesperidin methylchalcone (HMC) was evaluated through Alzheimer's disease models of Neuro-2a cells and Wistar rats. The in vitro results showed that HMC possesses significant ability to inhibit the acetylcholinesterase enzyme and exhibiting anti-aggregation and disaggregation properties. Furthermore, HMC could protect the Neuro-2a cells against Aβ-induced neurotoxicity. Simultaneously, HMC treatment significantly improved the cognitive deficits caused by Aβ-peptide on spatial memory in Wistar rats. HMC significantly enhanced the cholinergic effects by inhibiting AChE, BuChE, β-secretase activity, caspase-3 activity, and attenuating macromolecular damages and apoptosis. Notably, HMC reduced the Aβ-induced oxidative stress by activating the antioxidative defence enzymes. In addition, the HMC treatment suppressed the expression of immunocytokines such as p-NF-κB p65, p-IκBα, induced by Aβ; whereas upregulating Nrf2, HO-1 in brain homogenate. These results suggest that HMC could attenuate Aβ-induced neuroinflammation in brain via suppressing NF-κB signalling pathway and activating the Nrf2/HO-1 pathway, thereby improving memory and cognitive impairments in Wistar rats. Overall, the present study reports that HMC can act as a potent candidate with multi-faceted neuroprotective potential against Aβ-induced memory dysfunction in Wistar rats for the treatment of Alzheimer's disease.

Beyond the classical amyloid hypothesis in Alzheimer's disease: Molecular insights into current concepts of pathogenesis, therapeutic targets, and study models

Alzheimer's disease (AD) is one of the progressive neurodegenerative disorders and the most common cause of dementia in the elderly worldwide causing difficulties in the daily life of the patient. AD is characterized by the aberrant accumulation of β-amyloid plaques and tau protein-containing neurofibrillary tangles (NFTs) in the brain giving rise to neuroinflammation, oxidative stress, synaptic failure, and eventual neuronal cell death. The total cost of care in AD treatment and related health care activities is enormous and pharmaceutical drugs approved by Food and Drug Administration have not manifested sufficient efficacy in protection and therapy. In recent years, there are growing studies that contribute a fundamental understanding to AD pathogenesis, AD-associated risk factors, and pharmacological intervention. However, greater molecular process-oriented research in company with suitable experimental models is still of the essence to enhance the prospects for AD therapy and cell lines as a disease model are still the major part of this milestone. In this review, we provide an insight into molecular mechanisms, particularly the recent concept in gut-brain axis, vascular dysfunction and autophagy, and current models used in the study of AD. Here, we emphasized the importance of therapeutic strategy targeting multiple mechanisms together with utilizing appropriate models for the discovery of novel effective AD therapy. This article is categorized under: Neurological Diseases > Molecular and Cellular Physiology.

Antioxidant and anti-inflammation effects of dietary phytochemicals: The Nrf2/NF-κB signalling pathway and upstream factors of Nrf2

Oxidative stress (OS) is created by an imbalance between reactive oxygen species and antioxidant levels. OS promotes inflammation and is associated with many diseases, such as neurodegenerative disorders, diabetes, and cardiovascular disease. Nrf2 and NF-κB are critical in the cellular defence against OS and the regulators of inflammatory responses, respectively. Recent studies revealed that the Nrf2 signalling pathway interacts with the NF-κB signalling pathway in OS. More importantly, many natural compounds have long been recognized to ameliorate OS and inflammation via the Nrf2 and/or NF-κB signalling pathway. Thus, we briefly overview the potential crosstalk between Nrf2 and NF-κB and the upstream regulators of Nrf2 and review the literature on the antioxidant and anti-inflammatory effects of dietary phytochemicals (DPs) that can activate these defence systems. The aim is to provide evidence for the development of DPs into functional food for the regulation of the Nrf2/NF-κB signalling pathway by upstream regulators of Nrf2.

Signal pathways in the treatment of Alzheimer's disease with traditional Chinese medicine

AIM OF THE REVIEW

This study aimed to reveal the classical signal pathways and important potential targets of traditional Chinese medicine (TCM) for treating Alzheimer's disease (AD), and provide support for further investigation on TCM and its active ingredients.

MATERIALS AND METHODS

Literature survey was conducted using PubMed, Web of Science, Google Scholar, CNKI, and other databases, with "Alzheimer's disease," "traditional Chinese medicine," "medicinal herb," "Chinese herb," and "natural plant" as the primary keywords.

RESULTS

TCM could modulate signal pathways related to AD pathological progression, including NF-κB, Nrf2, JAK/STAT, ubiquitin-proteasome pathway, autophagy-lysosome pathway-related AMPK/mTOR, GSK-3/mTOR, and PI3K/Akt/mTOR, as well as SIRT1 and PPARα pathway. It could regulate crosstalk between pathways through a multitarget, thus maintaining chronic inflammatory interaction balance, inhibiting oxidative stress damage, regulating ubiquitin-proteasome system function, modulating autophagy, and eventually improving cognitive impairment in patients with AD.

CONCLUSION

TCM could be multilevel, multitargeted, and multifaceted to prevent and treat AD. In-depth research on the prevention and treatment of AD with TCM could provide new ideas for exploring the pathogenesis of AD and developing new anti-AD drugs.

γ-Glutamylcysteine attenuates amyloid-β oligomers-induced neuroinflammation in microglia via blocking NF-κB signaling pathway

Alzheimer's disease (AD) is the most prevalent neurogenerative disease, characterized by progressive memory loss and cognitive deficits. Intracellular neurofibrillary tangles (NFTs) and amyloid-β (Aβ)-formed neuritic plaques are major pathological features of AD. Aβ evokes activation of microglia to release inflammatory mediators and ROS to induce neurotoxicity, leading to neurodegeneration. γ-Glutamylcysteine (γ-GC), an intermediate dipeptide of the GSH-synthesis pathway and possessing anti-inflammatory and anti-oxidative properties, represents a relatively unexplored option for AD treatment. In the present study, we investigated the anti-inflammatory effect of γ-GC on Aβ oligomer (AβO)-induced neuroinflammation and the associated molecular mechanism in microglia. The results showed that γ-GC reduced AβO-induced release of tumor necrosis factor-α (TNF-α), interleukin-1β (IL-1β), and nitric oxide (NO), and the expression of inducible NO synthase (iNOS) and cyclooxygenase 2 (COX-2). γ-GC decreased ROS and MDA production and increased the GSH level, GSH/GSSG ratio, and SOD activity in AβO-treated microglia. Mechanistically, γ-GC inhibited activation of nuclear factor kappa B (NF-κB), and upregulated the nuclear receptor-related 1 (Nurr1) protein expression to suppress the transcriptional effect of NF-κB on the inflammatory genes. Besides, γ-GC suppressed the AβO-induced neuroinflammation in mice. These findings suggested that γ-GC might represent a potential therapeutic agent for anti-neuroinflammation.

Comprehensive review on signaling pathways of dietary saponins in cancer cells suppression

Nutrigenomics utilizes high-throughput genomic technologies to reveal changes in gene and protein levels. Excitingly, ever-growing body of scientific findings has provided sufficient evidence about the interplay between diet and genes. Cutting-edge research and advancements in genomics, epigenetics and metabolomics have deepened our understanding on the role of dietary factors in the inhibition of carcinogenesis and metastasis. Dietary saponins, a type of triterpene glycosides, are generally found in Platycodon grandifloras, Dioscorea oppositifolia, asparagus, legumes, and sea cucumber. Wealth of information has started to shed light on pleiotropic mechanistic roles of dietary saponins in cancer prevention and inhibition. In this review, we have attempted to summarize the in vitro research of dietary saponins in the last two decades by searching common databases such as Google Scholar, PubMed, Scopus, and Web of Science. The results showed that dietary saponins exerted anti-cancer activities via regulation of apoptosis, autophagy, arrest cell cycle, anti-proliferation, anti-metastasis, and anti-angiogenesis, by regulation of several critical signaling pathways, including MAPK, PI3K/Akt/mTOR, NF-κB, and VEGF/VEGFR. However, there is no data about the dosage of dietary saponins for practical anti-cancer effects in human bodies. Extensive clinical studies are needed to confirm the effectiveness of dietary saponins for further commercial and medical applications.

Improved production of deglucosylated platycodin D from saponins from balloon flower leaf by a food-grade enzyme using high hydrostatic pressure

Platycosides, saponins contained in balloon flower, which have been used as food health supplements for respiratory diseases, have diverse pharmacological effects. Platycosides exhibit better pharmacological activity by hydrolyzing their own sugars. However, to date, there have been no studies on the production of deglucosylated platycodin D suitable for food applications. In this study, Pluszyme 2000P, which was derived from Aspergillus niger, a food-grade microorganism, was used to completely convert platycoside E into deglucosylated platycodin D. For an efficient and economical production of deglucosylated platycodin D, the productivity was improved approximately 2.4 times by application of high hydrostatic pressure and the discarded balloon flower leaf was used as a substrate. As a result, deglucosylated platycodin D was produced with the highest concentration (3.49 mg/mL) and productivity (581.7 mg/L/h) reported so far. Our results contribute to functional saponin production and the related food industries.

Protective Effects of Novel Substituted Triazinoindole Inhibitors of Aldose Reductase and Epalrestat in Neuron-like PC12 Cells and BV2 Rodent Microglial Cells Exposed to Toxic Models of Oxidative Stress: Comparison with the Pyridoindole Antioxidant Stobadine

Aldose reductase (AR) catalyzes the conversion of glucose to sorbitol in a NADPH-dependent reaction, thereby increasing the production of reactive oxygen species (ROS). Since AR activation is linked to redox dysregulation and cell damage in neurodegenerative diseases, AR inhibitors (ARIs) constitute promising therapeutic tools for the treatment of these disorders. Among these compounds, the novel substituted triazinoindole derivatives cemtirestat (CMTI) and COTI, as well as the clinically employed epalrestat (EPA) and the pyridoindole-antioxidant stobadine (STB), were tested in both PC12 cells and BV2 microglia exposed to four different neurotoxic models. These include (1) oxidative stress with hydrogen peroxide (H₂O₂), (2) mitochondrial complex IV inhibition with NaN₃, (3) endoplasmic reticulum-stress and lipotoxicity induced by palmitic acid/bovine serum albumin (PAM/BSA), and (4) advanced carbonyl compound lipotoxicity by 4-hydroxynonenal (4-HNE). All toxic compounds decreased cell viability and increased ROS formation in both PC12 and BV2 cells in a concentration-dependent manner (1-1000 μM; NaN₃ < H₂O₂≈PAM/BSA < 4-HNE). In PC12 cells, EPA increased cell viability in all toxic models only at 1 μM, whereas CMTI restored baseline viability in all toxic models. COTI afforded protection against lipotoxicity, while STB only prevented H₂O₂-induced toxicity. Except for the 4-HNE model, EPA prevented ROS generation in all other toxic models, whereas CMTI, COTI, and STB prevented ROS production in all toxic models. In BV2 cells, EPA and CMTI restored baseline cell viability in all toxic models tested, while COTI and STB did not prevent the loss of viability in the NaN₃ model. All ARIs and STB efficiently prevented ROS formation in all toxic models in a concentration-independent manner. The differential protective effects evoked by the novel ARIs and STB on the toxic models tested herein provide novel and relevant comparative evidence for the design of specific therapeutic strategies against neurodegenerative events associated with neurological disorders.