Cognitive-enhancing effect of polysaccharides from Flammulina velutipes on Alzheimer's disease by compatibilizing with ginsenosides

Emerging paradigms in Alzheimer's therapy

Alzheimer's disease is a neurodegenerative disorder that affects elderly, and its incidence is continuously increasing across the globe. Unfortunately, despite decades of research, a complete cure for Alzheimer's disease continues to elude us. The current medications are mainly symptomatic and slow the disease progression but do not result in reversal of all disease pathologies. The growing body of knowledge on the factors responsible for the onset and progression of the disease has resulted in the identification of new targets that could be targeted for treatment of Alzheimer's disease. This has opened new vistas for treatment of Alzheimer's disease that have moved away from chemotherapeutic agents modulating a single target to biologics and combinations that acted on multiple targets thereby offering better therapeutic outcomes. This review discusses the emerging directions in therapeutic interventions against Alzheimer's disease highlighting their merits that promise to change the treatment paradigm and challenges that limit their clinical translation.

Potential therapeutic natural compounds for the treatment of Alzheimer's disease

BACKGROUND

Alzheimer's disease (AD) is a complicated neurodegenerative disease with cognitive impairment occurring in the older people, in which extracellular accumulation of β-amyloid and intracellular aggregation of hyperphosphorylated tau are regarded as the prevailing theories. However, the exact AD mechanism has not been determined. Moreover, there is no effective treatment available in phase III trials to eradicate AD, which is imperative to explore novel treatments.

PURPOSE

A number of up-to-date pre-clinical studies on cognitive impairment is beneficial to clarify the pathology of AD. This review recapitulates several advances in AD pathobiology and discusses the neuroprotective effects of natural compounds, such as phenolic compounds, natural polysaccharides and oligosaccharides, peptide, and lipids, underscoring the therapeutic potential for AD.

METHODS

Electronic databases involving PubMed, Web of Science, and Google Scholar were searched up to October 2023. Articles were conducted using the keywords like Alzheimer's disease, pathogenic mechanisms, natural compounds, and neuroprotection.

RESULT

This review summarized several AD pathologies and the neuroprotective effects of natural compounds such as natural polysaccharides and oligosaccharides, peptide, and lipids.

CONCLUSION

We have discussed the pathogenic mechanisms of AD and the effect natural products on neurodegenerative diseases particularly in treating AD. Specifically, we investigated the molecular pathways and links between natural compounds and Alzheimer's disease such as through NF-κB, Nrf2, and mTOR pathway. Further investigation is necessary in exploring the bioactivity and effectiveness of natural compounds in clinical trials, which may provide a promising treatment for AD patients.

Research progress and future development potential of Flammulina velutipes polysaccharides in the preparation process, structure analysis, biology, and pharmacology: A review

In recent years, Flammulina velutipes (F. velutipes) has attracted consequential attention in various research fields due to its rich composition of proteins, vitamins, amino acids, polysaccharides, and polyphenols. F. velutipes polysaccharides (FVPs) are considered as key bioactive components of F. velutipes, demonstrating multiple physiological activities, including immunomodulatory, anti-inflammatory, and antibacterial properties. Moreover, they offer health benefits such as antioxidant and anti-aging properties, which have exceptionally valuable clinical applications. Polysaccharides derived from different sources exhibit a wide range of biomedical functions and distinct biological activities. The varied biological functions of polysaccharides, coupled with their extensive application in functional foods and clinical applications, have prompted a heightened focus on polysaccharide research. Additionally, the extraction, deproteinization, and purification of FVPs are fundamental to investigate the structure and biological activities of polysaccharides. Therefore, this review provides a comprehensive and systematic overview of the extraction, deproteinization, purification, characterization, and structural elucidation of FVPs. Furthermore, the biological activities and mechanisms of FVPs have been further explored through in vivo and in vitro experiments. This review aims to provide a theoretical foundation and guide future research and development of FVPs.

Neuroprotective potential of Erigeron bonariensis ethanolic extract against ovariectomized/D-galactose-induced memory impairments in female rats in relation to its metabolite fingerprint as revealed using UPLC/MS

Erigeron bonariensis is widely distributed throughout the world's tropics and subtropics. In folk medicine, E. bonariensis has historically been used to treat head and brain diseases. Alzheimer's disease (AD) is the most widespread form of dementia initiated via disturbances in brain function. Herein, the neuroprotective effect of the chemically characterized E. bonariensis ethanolic extract is reported for the first time in an AD animal model. Chemical profiling was conducted using UPLC-ESI-MS analysis. Female rats underwent ovariectomy (OVX) followed by 42 days of D-galactose (D-Gal) administration (150 mg/kg/day, i.p) to induce AD. The OVX/D-Gal-subjected rats received either donepezil (5 mg/kg/day) or E. bonariensis at 50, 100, and 200 mg/kg/day, given 1 h prior to D-Gal. UPLC-ESI-MS analysis identified 42 chemicals, including flavonoids, phenolic acids, terpenes, and nitrogenous constituents. Several metabolites, such as isoschaftoside, casticin, velutin, pantothenic acid, xanthurenic acid, C18-sphingosine, linoleamide, and erucamide, were reported herein for the first time in Erigeron genus. Treatment with E. bonariensis extract mitigated the cognitive decline in the Morris Water Maze test and the histopathological alterations in cortical and hippocampal tissues of OVX/D-Gal-subjected rats. Moreover, E. bonariensis extract mitigated OVX/D-Gal-induced Aβ aggregation, Tau hyperphosphorylation, AChE activity, neuroinflammation (NF-κBp65, TNF-α, IL-1β), and apoptosis (Cytc, BAX). Additionally, E. bonariensis extract ameliorated AD by increasing α7-nAChRs expression, down-regulating GSK-3β and FOXO3a expression, and modulating Jak2/STAT3/NF-ĸB p65 and PI3K/AKT signaling cascades. These findings demonstrate the neuroprotective and memory-enhancing effects of E. bonariensis extract in the OVX/D-Gal rat model, highlighting its potential as a promising candidate for AD management.

Mechanisms and structure-activity relationships of polysaccharides in the intervention of Alzheimer's disease: A review

Alzheimer's disease (AD) is a complex neurodegenerative disease. Despite several decades of research, the development of effective treatments and responses for Alzheimer's disease remains elusive. The utilization of polysaccharides for Alzheimer's disease became more popular due to their beneficial characteristics, notably their multi-target activity and low toxicity. This review mainly focuses on the researches of recent 5 years in the regulation of AD by naturally derived polysaccharides, systematically lists the possible intervention pathways of polysaccharides from different mechanisms, and explores the structure-activity relationship between polysaccharide structural activities, so as to provide references for the intervention and treatment of AD by polysaccharides.

Unveiling the neuroprotective potential of dietary polysaccharides: a systematic review

Central nervous system (CNS) disorders present a growing and costly global health challenge, accounting for over 11% of the diseases burden in high-income countries. Despite current treatments, patients often experience persistent symptoms that significantly affect their quality of life. Dietary polysaccharides have garnered attention for their potential as interventions for CNS disorders due to their diverse mechanisms of action, including antioxidant, anti-inflammatory, and neuroprotective effects. Through an analysis of research articles published between January 5, 2013 and August 30, 2023, encompassing the intervention effects of dietary polysaccharides on Alzheimer's disease, Parkinson's disease, depression, anxiety disorders, autism spectrum disorder, epilepsy, and stroke, we have conducted a comprehensive review with the aim of elucidating the role and mechanisms of dietary polysaccharides in various CNS diseases, spanning neurodegenerative, psychiatric, neurodevelopmental disorders, and neurological dysfunctions. At least four categories of mechanistic bases are included in the dietary polysaccharides' intervention against CNS disease, which involves oxidative stress reduction, neuronal production, metabolic regulation, and gut barrier integrity. Notably, the ability of dietary polysaccharides to resist oxidation and modulate gut microbiota not only helps to curb the development of these diseases at an early stage, but also holds promise for the development of novel therapeutic agents for CNS diseases. In conclusion, this comprehensive review strives to advance therapeutic strategies for CNS disorders by elucidating the potential of dietary polysaccharides and advocating interdisciplinary collaboration to propel further research in this realm.

Polysaccharides: potential bioactive macromolecules for Alzheimer's disease

Alzheimer's disease (AD) is one of the leading causes of death and disability. AD is a devastating disease that has caused an overwhelming burden. However, no disease-modified treatment was discovered. The approval of sodium oligomannate (GV-971) in mild-moderate AD patients has attracted great attention to investigate the role of saccharides in AD. Therefore, summarizing and explaining the role of saccharides in AD is urgent and promising. Recent studies showed that polysaccharides (PSs) potentially benefit AD in vitro and in vivo. PSs could alleviate the pathological damage and improve cognitive symptoms via (1) antagonizing the toxicity of abnormal amyloid-beta and tau proteins; (2) attenuating oxidative stress and proinflammation; (3) rebuilding neuroplasticity. PSs exhibit one-multiple pathological hits of AD. However, a thorough chemical investigation is needed for further study.

Unveiling the Therapeutic Potentials of Mushroom Bioactive Compounds in Alzheimer's Disease

Alzheimer's disease (AD) stands as a prevailing neurodegenerative condition (NDs), leading to the gradual deterioration of brain cells and subsequent declines in memory, thinking, behavior, and emotion. Despite the intensive research efforts and advances, an effective curative treatment for the disease has not yet been found. Mushrooms, esteemed globally for their exquisite flavors and abundant nutritional benefits, also hold a wealth of health-promoting compounds that contribute to improving AD health. These compounds encompass polysaccharides, proteins, lipids, terpenoids, phenols, and various other bioactive substances. Particularly noteworthy are the potent neuroprotective small molecules found in mushrooms, such as ergothioneine, erinacine, flavonoids, alkaloids, ergosterol, and melanin, which warrant dedicated scrutiny for their therapeutic potential in combating AD. This review summarizes such positive effects of mushroom bioactive compounds on AD, with a hope to contribute to the development of functional foods as an early dietary intervention for this neurodegenerative disease.

Multiple Metabolites Derived from Mushrooms and Their Beneficial Effect on Alzheimer's Diseases

Mushrooms with edible and medicinal potential have received widespread attention because of their diverse biological functions, nutritional value, and delicious taste, which are closely related to their rich active components. To date, many bioactive substances have been identified and purified from mushrooms, including proteins, carbohydrates, phenols, and vitamins. More importantly, molecules derived from mushrooms show great potential to alleviate the pathological manifestations of Alzheimer's disease (AD), which seriously affects the health of elderly people. Compared with current therapeutic strategies aimed at symptomatic improvement, it is particularly important to identify natural products from resource-rich mushrooms that can modify the progression of AD. This review summarizes recent investigations of multiple constituents (carbohydrates, peptides, phenols, etc.) isolated from mushrooms to combat AD. In addition, the underlying molecular mechanisms of mushroom metabolites against AD are discussed. The various mechanisms involved in the antiAD activities of mushroom metabolites include antioxidant and anti-neuroinflammatory effects, apoptosis inhibition, and stimulation of neurite outgrowth, etc. This information will facilitate the application of mushroom-derived products in the treatment of AD. However, isolation of new metabolites from multiple types of mushrooms and further in vivo exploration of the molecular mechanisms underlying their antiAD effect are still required.

Biopharmaceutical applications of microbial polysaccharides as materials: A review

Biological characteristics of natural polymers make microbial polysaccharides an excellent choice for biopharmaceuticals. Due to its easy purifying procedure and high production efficiency, it is capable of resolving the existing application issues associated with some plant and animal polysaccharides. Furthermore, microbial polysaccharides are recognized as prospective substitutes for these polysaccharides based on the search for eco-friendly chemicals. In this review, the microstructure and properties of microbial polysaccharides are utilized to highlight their characteristics and potential medical applications. From the standpoint of pathogenic processes, in-depth explanations are provided on the effects of microbial polysaccharides as active ingredients in the treatment of human diseases, anti-aging, and drug delivery. In addition, the scholarly developments and commercial applications of microbial polysaccharides as medical raw materials are also discussed. The conclusion is that understanding the use of microbial polysaccharides in biopharmaceuticals is essential for the future development of pharmacology and therapeutic medicine.

Mushroom Polysaccharides as Potential Candidates for Alleviating Neurodegenerative Diseases

Neurodegenerative diseases (NDs) are a widespread and serious global public health burden, particularly among the older population. At present, effective therapies do not exist, despite the increasing understanding of the different mechanisms of NDs. In recent years, some drugs, such as galantamine, entacapone, riluzole, and edaravone, have been proposed for the treatment of different NDs; however, they mainly concentrate on symptom management and confer undesirable side effects and adverse reactions. Therefore, there is an urgent need to find novel drugs with fewer disadvantages and higher efficacy for the treatment of NDs. Mushroom polysaccharides are macromolecular complexes with multi-targeting bioactivities, low toxicity, and high safety. Some have been demonstrated to exhibit neuroprotective effects via their antioxidant, anti-amyloidogenic, anti-neuroinflammatory, anticholinesterase, anti-apoptotic, and anti-neurotoxicity activities, which have potential in the treatment of NDs. This review focuses on the different processes involved in ND development and progression, highlighting the neuroprotective activities and potential role of mushroom polysaccharides and summarizing the limitations and future perspectives of mushroom polysaccharides in the prevention and treatment of NDs.

Potential for non-starch polysaccharides in the prevention and remediation of cognitive impairment: A comprehensive review

Non-starch polysaccharides (NSPs) are food ingredients proven to be beneficial in a large number of health issues. However, there is no literature systematic review about the effects and corresponding mechanisms of NSPs on the prevention and remediation of cognitive impairment. In this review, studies on prevention and remediation of NSPs for cognitive deficit caused by diseases, menopause, ageing, chronic stress and environmental pollutants were summarized and the corresponding mechanisms were established. The anti-cognitive deficit effects of NSPs were associated with the modulation of amyloid β (Aβ) deposition, p-Tau aggregation, oxidative stress, inflammation, neuron apoptosis, neurogenesis, neurotransmitters, synaptic plasticity, autophagy and gut microbiota. Although the structure-function relationship has not been elucidated, several structural properties of NSPs such as molecular weight, sulfate content, hydroxyl group content, monosaccharide composition and molecular chain linkage might be crucial for the anti-cognitive deficit property. Notably, this review revealed that NSPs had a positive effect on cognitive impairment and proposed the future perspectives for further research on the anti-cognitive dysfunction effects of NSPs.

Natural Polysaccharides as Preventive and Therapeutic Horizon for Neurodegenerative Diseases

Neurodegenerative diseases are a serious and widespread global public health burden amongst aging populations. The total estimated worldwide global cost of dementia was US$818 billion in 2015 and has been projected to rise to 2 trillion US$ by 2030. While advances have been made to understand different neurodegenerative disease mechanisms, effective therapeutic strategies do not generally exist. Several drugs have been proposed in the last two decades for the treatment of different types of neurodegenerative diseases, with little therapeutic benefit, and often with severe adverse and side effects. Thus, the search for novel drugs with higher efficacy and fewer drawbacks is an ongoing challenge in the treatment of neurodegenerative disease. Several natural compounds including polysaccharides have demonstrated neuroprotective and even therapeutic effects. Natural polysaccharides are widely distributed in plants, animals, algae, bacterial and fungal species, and have received considerable attention for their wide-ranging bioactivity, including their antioxidant, anti-neuroinflammatory, anticholinesterase and anti-amyloidogenic effects. In this review, we summarize different mechanisms involved in neurodegenerative diseases and the neuroprotective effects of natural polysaccharides, highlighting their potential role in the prevention and therapy of neurodegenerative disease.

Optimization of the Nutrient Medium for Flammulina velutipes Submerged Biomass Production and Micromorphology of Its Mycelium

Based on the assessment of the trophic needs of basidiomycete Flammulina velutipes and the optimization of the composition of the nutrient medium using design of experimental approach, the yield of the submerged biomass of the fungus was increased to 41 g/L, the duration of the cultivation process was reduced to 5 days. For this purpose, the 24 full factorial design, the Box–Wilson steep ascent method and the construction of the response surface were used. Using the method of scanning electron microscopy, it was shown that the studied F. velutipes strain grew in the form of small spherical pellets with a diameter of 1–2 mm on an optimized medium. The surface of the pellets was loose; the inner part was filled with hyphae tightly adjacent to each other. The center of the pellets had no cavity. F. velutipes pellets were formed by septate hyphae with clamp connections. The micromorphological characteristics of the submerged F. velutipes mycelium ensured a high diffusion of nutrients and oxygen into the pellets and their maximum filling of the volume of the culture medium.

Characterization of soy protein isolate/Flammulina velutipes polysaccharide hydrogel and its immunostimulatory effects on RAW264.7 cells

Soy protein isolate (SPI) is a nutritional commercial product, while the poor solubility and gelling restricts its applications for functional foods. To surmount the challenge presented by this poor solubility, the gelling polysaccharide shows potential in ameliorating SPI. In this study, SPI/Flammulina velutipes polysaccharide (FVP) hydrogels were prepared under four mixing ratios (32:1, 20:1,15:1 and 10:1, w/w) at both pH6.5 and pH3.5, respectively. The stability of hydrogels and its immunostimulatory impact on RAW264.7 cells were assessed. Initial results revealed that water holding capacity increased when increasing the mixing ratios, likely to be the results of enhanced electrostatic interaction between SPI and FVP. The addition of FVP contributed to the improved swelling ratio and lowered the degradation ratio. Such structure feature was shown to be favorable for hydrogels to culture cells. More importantly, SPI/FVP hydrogels demonstrated no cytotoxic effect on cell metabolic activity. The culture of SPI/FVP hydrogels enhanced the immunostimulatory capacity in RAW264.7 cells by increasing phagocytosis and inducing the production of pro-inflammatory cytokines. The performances of the hydrogels made at pH3.5 were superior to those prepared at pH6.5. Our results suggested SPI/FVP hydrogels may provide application potential for the development of functional foods.

Therapeutic applications of mushrooms and their biomolecules along with a glimpse of in silico approach in neurodegenerative diseases

Neurodegenerative diseases (NDs) represent a common neurological pathology that determines a progressive deterioration of the brain or the nervous system. For treating NDs, comprehensive and alternative medicines have attracted scientific researchers' attention recently. Edible mushrooms are essential for preventing several age-based neuronal dysfunctions such as Parkinson's and Alzheimer's diseases. Mushroom such as Grifola frondosa, Lignosus rhinocerotis, Hericium erinaceus, may improve cognitive functions. It has also been reported that edible mushrooms (basidiocarps/mycelia extracts or isolated bioactive compounds) may reduce beta-amyloid-induced neurotoxicity. Medicinal mushrooms are being used for novel and natural compounds that help modulate immune responses and possess anti-cancer, anti-microbial, and anti-oxidant properties. Compounds such as polyphenols, terpenoids, alkaloids, sesquiterpenes, polysaccharides, and metal chelating agents are validated in different ND treatments. This review aims to assess mushrooms' role and their biomolecules utilization for treating different kinds of NDs. The action mechanisms, presented here, including reducing oxidative stress, neuroinflammation, and modulation of acetylcholinesterase activity, protecting neurons or stimulation, and regulating neurotrophins synthesis. We also provide background about neurodegenerative diseases and in-silico techniques of the drug research. High costs associated with experiments and current ethical law imply efficient alternatives with limited cost value. In silico approaches provide an alternative method with low cost that has been successfully implemented to cure ND disorders in recent days. We also describe the applications of computational procedures such as molecular docking, virtual high-throughput screening, molecular dynamic (MD) simulation, quantum-mechanical methods for drug design. They were reported against various targets in NDs.

The water-soluble non-starch polysaccharides from natural resources against excessive oxidative stress: A potential health-promoting effect and its mechanisms

The water-soluble non-starch polysaccharides isolated from natural resources have become research hotpots in the field of food science and human health due to widely distributed in nature and low toxicity. It has indicated that the health-promoting effect of water-soluble non-starch polysaccharides were partly attributable to against excessive oxidative stress. Indeed, excessive oxidative stress in the body has been reported in occurrence of disease. The water-soluble non-starch polysaccharides from natural resources exhibit antioxidant activity to against oxidative stress via scavenging free radicals promoting antioxidant enzymes activity and/or regulating antioxidant signaling pathways. In this review, the water-soluble non-starch polysaccharides as medicine agent and the factor affecting antioxidant as well as the relationship between oxidative stress and disease are summarized, and the mechanisms of water-soluble non-starch polysaccharides therapy in disease are also discussed. It will provide a theoretical basis for natural polysaccharides used for the treatment of diseases.

Advances in the extraction, purification, structural-property relationships and bioactive molecular mechanism of Flammulina velutipes polysaccharides: A review

With the further research in recent years, Flammulina velutipes (F. velutipes), an edible mushroom, has great application value in many fields. As one of the main bioactive components in F. velutipes, polysaccharide has a series of functions such as anti-oxidation, immune regulation, anti-inflammation, liver protection, anti-tumor, anti-hyperlipidemia and so on. In this paper, the current progress in the extraction, purification, structural characteristics and bioactivities of F. velutipes polysaccharides (FVPs) were reviewed. Meanwhile, the structural-property relationships of FVPs were further discussed. In addition, based on in vitro and in vivo experiments, the possible mechanisms of bioactivities of FVPs were summarized. In order to understand FVPs more comprehensively, the application status and the future research work of FVPs were also introduced. Finally, we hope that our research can provide a reference for further research and development of FVPs.

Critical Review of the Alzheimer's Disease Non-Transgenic Models: Can They Contribute to Disease Treatment?

Alzheimer's disease (AD) is a growing neurodegenerative disease without effective treatments or therapies. Despite the use of different approaches and an extensive variety of genetic amyloid based models, therapeutic strategies remain elusive. AD is characterized by three main pathological hallmarks that include amyloid-β plaques, neurofibrillary tangles, and neuroinflammatory processes; however, many other pathological mechanisms have been described in the literature. Nonetheless, the study of the disease and the screening of potential therapies is heavily weighted toward the study of amyloid-β transgenic models. Non-transgenic models may aid in the study of complex pathological states and provide a suitable complementary alternative to evaluating therapeutic biomedical and intervention strategies. In this review, we evaluate the literature on non-transgenic alternatives, focusing on the use of these models for testing therapeutic strategies, and assess their contribution to understanding AD. This review aims to underscore the need for a shift in preclinical research on intervention strategies for AD from amyloid-based to alternative, complementary non-amyloid approaches.

Characterization, Antioxidant, Anti-Aging and Organ Protective Effects of Sulfated Polysaccharides from Flammulina velutipes

As an irreversible and complex degenerative physiological process, the treatment for aging seems strategically necessary, and polysaccharides play important roles against aging owing to their abundant bioactivities. In this paper, the antioxidant and anti-aging activities of Flammulina velutipes polysaccharides (FPS) and its sulfated FPS (SFPS) on d-galactose-induced aging mice were investigated. The in vitro antioxidant activities demonstrated that SFPS had strong reducing power and superior scavenging effects on 2, 2-diphenylpicrylhydrazyl (DPPH), hydroxyl radicals and the chelating activities of Fe²⁺. The in vivo animal experiments manifested that the SFPS showed superior antioxidant and protective abilities against the d-galactose-induced aging by increasing the antioxidant enzyme activities, decreasing lipid peroxidation, improving the inflammatory response and ameliorating the anile condition of mice. Furthermore, the structural analysis of SFPS was investigated through FT-IR, NMR, and HPLC analysis, and the results indicated that SFPS was a homogeneous heteropolysaccharide with a weight-average molecular weight of 2.81 × 10³ Da. Furthermore, SFPS has also changed in characteristic functional groups and monosaccharide composition compared to FPS. These results suggested that sulfated modification could enhance the anti-oxidation, anti-aging and protective activities of F. velutipes polysaccharides, which may provide references for the development of functional foods and natural medicines.