Neferine attenuates the protein level and toxicity of mutant huntingtin in PC-12 cells via induction of autophagy

The role of neuron-like cell lines and primary neuron cell models in unraveling the complexity of neurodegenerative diseases: a comprehensive review

Neurodegenerative diseases (NDs) are characterized by the progressive loss of neurons. As to developing effective therapeutic interventions, it is crucial to understand the underlying mechanisms of NDs. Cellular models have become invaluable tools for studying the complex pathogenesis of NDs, offering insights into disease mechanisms, determining potential therapeutic targets, and aiding in drug discovery. This review provides a comprehensive overview of various cellular models used in ND research, focusing on Alzheimer's disease, Parkinson's disease, Huntington's disease, and amyotrophic lateral sclerosis. Cell lines, such as SH-SY5Y and PC12 cells, have emerged as valuable tools due to their ease of use, reproducibility, and scalability. Additionally, co-culture models, involving the growth of distinct cell types like neurons and astrocytes together, are highlighted for simulating brain interactions and microenvironment. While cell lines cannot fully replicate the complexity of the human brain, they provide a scalable method for examining important aspects of neurodegenerative diseases. Advancements in cell line technologies, including the incorporation of patient-specific genetic variants and improved co-culture models, hold promise for enhancing our understanding and expediting the development of effective treatments. Integrating multiple cellular models and advanced technologies offers the potential for significant progress in unraveling the intricacies of these debilitating diseases and improving patient outcomes.

Natural autophagy modulators in non-communicable diseases: from autophagy mechanisms to therapeutic potential

Non-communicable diseases (NCDs) are defined as a kind of diseases closely related to bad behaviors and lifestyles, e.g., cardiovascular diseases, cancer, and diabetes. Driven by population growth and aging, NCDs have become the biggest disease burden in the world, and it is urgent to prevent and control these chronic diseases. Autophagy is an evolutionarily conserved process that degrade cellular senescent or malfunctioning organelles in lysosomes. Mounting evidence has demonstrated a major role of autophagy in the pathogenesis of cardiovascular diseases, cancer, and other major human diseases, suggesting that autophagy could be a candidate therapeutic target for NCDs. Natural products/phytochemicals are important resources for drugs against a wide variety of diseases. Recently, compounds from natural plants, such as resveratrol, curcumin, and ursolic acid, have been recognized as promising autophagy modulators. In this review, we address recent advances and the current status of the development of natural autophagy modulators in NCDs and provide an update of the latest in vitro and in vivo experiments that pave the way to clinical studies. Specifically, we focus on the relationship between natural autophagy modulators and NCDs, with an intent to identify natural autophagy modulators with therapeutic potential.

Dual regulatory effects of neferine on amyloid-β and tau aggregation studied by in silico, in vitro, and lab-on-a-chip technology

Alzheimer's disease (AD) is characterized by the presence of two critical pathogenic factors: amyloid-β (Aβ) and tau. Aβ and tau become neurotoxic aggregates via self-assembly, and these aggregates contribute to the pathogenesis of AD. Therefore, there has been growing interest in therapeutic strategies that simultaneously target Aβ and tau aggregates. Although neferine has attracted attention as a suitable candidate agent for alleviating AD pathology, there has been no study investigating whether neferine affects the modulation of Aβ or tau aggregation/dissociation. Herein, we investigated the dual regulatory effects of neferine on Aβ and tau aggregation/dissociation. We predicted the binding characteristics of neferine to Aβ and tau using molecular docking simulations. Next, thioflavin T and atomic force microscope analyses were used to evaluate the effects of neferine on the aggregation or dissociation of Aβ42 and tau K18. We verified the effect of neferine on Aβ fibril degradation using a microfluidic device. In addition, molecular dynamics simulation was used to predict a conformational change in the Aβ42-neferine complex. Moreover, we examined the neuroprotective effect of neferine against neurotoxicity induced by Aβ and tau and their fibrils in HT22 cells. Finally, we foresaw the pharmacokinetic properties of neferine. These results demonstrated that neferine, which has attracted attention as a potential treatment for AD, can directly affect Aβ and tau pathology.

A clinical study and future prospects for bioactive compounds and semi-synthetic molecules in the therapies for Huntington's disease

A neurodegenerative disorder (ND) refers to Huntington's disease (HD) which affects memory loss, weight loss, and movement dysfunctions such as chorea and dystonia. In the striatum and brain, HD most typically impacts medium-spiny neurons. Molecular genetics, excitotoxicity, oxidative stress (OS), mitochondrial, and metabolic dysfunction are a few of the theories advanced to explicit the pathophysiology of neuronal damage and cell death. Numerous in-depth studies of the literature have supported the therapeutic advantages of natural products in HD experimental models and other treatment approaches. This article briefly discusses the neuroprotective impacts of natural compounds against HD models. The ability of the discovered natural compounds to suppress HD was tested using either in vitro or in vivo models. Many bioactive compounds considerably lessened the memory loss and motor coordination brought on by 3-nitropropionic acid (3-NP). Reduced lipid peroxidation, increased endogenous enzymatic antioxidants, reduced acetylcholinesterase activity, and enhanced mitochondrial energy generation have profoundly decreased the biochemical change. It is significant since histology showed that therapy with particular natural compounds lessened damage to the striatum caused by 3-NP. Moreover, natural products displayed varying degrees of neuroprotection in preclinical HD studies because of their antioxidant and anti-inflammatory properties, maintenance of mitochondrial function, activation of autophagy, and inhibition of apoptosis. This study highlighted about the importance of bioactive compounds and their semi-synthetic molecules in the treatment and prevention of HD.

Role of Autophagy and Mitophagy in Neurodegenerative Disorders

Autophagy is a self-destructive cellular process that removes essential metabolites and waste from inside the cell to maintain cellular health. Mitophagy is the process by which autophagy causes disruption inside mitochondria and the total removal of damaged or stressed mitochondria, hence enhancing cellular health. The mitochondria are the powerhouses of the cell, performing essential functions such as ATP (adenosine triphosphate) generation, metabolism, Ca2+ buffering, and signal transduction. Many different mechanisms, including endosomal and autophagosomal transport, bring these substrates to lysosomes for processing. Autophagy and endocytic processes each have distinct compartments, and they interact dynamically with one another to complete digestion. Since mitophagy is essential for maintaining cellular health and using genetics, cell biology, and proteomics techniques, it is necessary to understand its beginning, particularly in ubiquitin and receptor-dependent signalling in injured mitochondria. Despite their similar symptoms and emerging genetic foundations, Alzheimer's disease (AD), Parkinson's disease (PD), Huntington's disease (HD), and amyotrophic lateral sclerosis (ALS) have all been linked to abnormalities in autophagy and endolysosomal pathways associated with neuronal dysfunction. Mitophagy is responsible for normal mitochondrial turnover and, under certain physiological or pathological situations, may drive the elimination of faulty mitochondria. Due to their high energy requirements and post-mitotic origin, neurons are especially susceptible to autophagic and mitochondrial malfunction. This article focused on the importance of autophagy and mitophagy in neurodegenerative illnesses and how they might be used to create novel therapeutic approaches for treating a wide range of neurological disorders.

Liensinine and neferine exert neuroprotective effects via the autophagy pathway in transgenic Caenorhabditis elegans

BACKGROUND

Liensinine and neferine are the main bisbenzylisoquinoline alkaloids obtained from the seeds of Nelumbo nucifera, which commonly used as edible food and traditional medicine in Asia. It was reported that liensinine and neferine could inhibit the activities of acetylcholinesterase and cross the blood-brain barriers, suggesting their therapeutic potential for the management of Alzheimer's disease.

METHODS

Here, we employed SH-SY5Y human neuroblastoma cells stably transfected with the human Swedish amyloid precursor protein (APP) mutation APP695 (APP695swe SH-SY5Y) as an in vitro model and transgenic Caenorhabditis elegans as an in vivo model to investigate the neuroprotective effects and underlying mechanism of liensinine and neferine.

RESULTS

We found that liensinine and neferine could significantly improve the viability and reduce ROS levels in APP695swe SH-SY5Y cells, inhibit β-amyloid and tau-induced toxicity, and enhance stress resistance in nematodes. Moreover, liensinine and neferine had obviously neuroprotective effects by assaying chemotaxis, 5-hydroxytryptamine sensitivity and the integrity of injured neurons in nematodes. Preliminary mechanism studies revealed that liensinine and neferine could upregulate the expression of autophagy related genes (lgg-1, unc-51, pha-4, atg-9 and ced-9) and reduce the accumulation of β-amyloid induced autophagosomes, which suggested autophagy pathway played a key role in neuroprotective effects of these two alkaloids.

CONCLUSIONS

Altogether, our findings provided a certain working foundation for the use of liensinine and neferine to treat Alzheimer's disease based on neuroprotective effects.

Neferine Targets the Oncogenic Characteristics of Androgen-Dependent Prostate Cancer Cells via Inducing Reactive Oxygen Species

Castration resistance poses a significant challenge in the management of advanced prostate cancer (PCa), with androgen deprivation therapy (ADT) or chemotherapy being the primary treatment options. However, these approaches often lead to significant side effects and the development of therapeutic resistance. Therefore, it is crucial to explore novel treatment options that can efficiently target PCa, improve patient survival, and enhance their quality of life. Neferine (Nef), a bioactive compound derived from plants, has emerged as a promising candidate for cancer treatment due to its ability to induce apoptosis, autophagy, and cell cycle arrest. In this study, we investigated the potential anticancer effects of Nef in androgen receptor (AR)-positive LNCaP and VCaP cells, representative models of androgen-dependent PCa. Our findings demonstrate that Nef effectively inhibits cell growth, proliferation, and the tumorigenic potential of androgen-dependent PCa cells. Furthermore, Nef treatment resulted in the excessive production of reactive oxygen species (ROS), leading to the activation of key markers of autophagy and apoptosis. These results suggest that Nef has the potential to target the oncogenic characteristics of androgen-dependent PCa cells by exploiting the potency of ROS and inducing autophagy and apoptosis in AR-positive PCa cells. These findings shed light on the therapeutic potential of Nef as a novel treatment option with reduced side effects for androgen-dependent prostate cancer. Further investigations are warranted to assess its efficacy and safety in preclinical and clinical settings.

Polyphenols, Autophagy and Neurodegenerative Diseases: A Review

Polyphenols are secondary metabolites from plant origin and are shown to possess a wide range of therapeutic benefits. They are also reported as regulators of autophagy, inflammation and neurodegeneration. The autophagy pathway is vital in degrading outdated organelles, proteins and other cellular wastes. The dysregulation of autophagy causes proteinopathies, mitochondrial dysfunction and neuroinflammation thereby contributing to neurodegeneration. Evidence reveals that polyphenols improve autophagy by clearing misfolded proteins in the neurons, suppress neuroinflammation and oxidative stress and also protect from neurodegeneration. This review is an attempt to summarize the mechanism of action of polyphenols in modulating autophagy and their involvement in pathways such as mTOR, AMPK, SIRT-1 and ERK. It is evident that polyphenols cause an increase in the levels of autophagic proteins such as beclin-1, microtubule-associated protein light chain (LC3 I and II), sirtuin 1 (SIRT1), etc. Although it is apparent that polyphenols regulate autophagy, the exact interaction of polyphenols with autophagy markers is not known. These data require further research and will be beneficial in supporting polyphenol supplementation as a potential alternative treatment for regulating autophagy in neurodegenerative diseases.

Research Progress on Neuroprotective Effects of Isoquinoline Alkaloids

Neuronal injury and apoptosis are important causes of the occurrence and development of many neurodegenerative diseases, such as cerebral ischemia, Alzheimer's disease, and Parkinson's disease. Although the detailed mechanism of some diseases is unknown, the loss of neurons in the brain is still the main pathological feature. By exerting the neuroprotective effects of drugs, it is of great significance to alleviate the symptoms and improve the prognosis of these diseases. Isoquinoline alkaloids are important active ingredients in many traditional Chinese medicines. These substances have a wide range of pharmacological effects and significant activity. Although some studies have suggested that isoquinoline alkaloids may have pharmacological activities for treating neurodegenerative diseases, there is currently a lack of a comprehensive summary regarding their mechanisms and characteristics in neuroprotection. This paper provides a comprehensive review of the active components found in isoquinoline alkaloids that have neuroprotective effects. It thoroughly explains the various mechanisms behind the neuroprotective effects of isoquinoline alkaloids and summarizes their common characteristics. This information can serve as a reference for further research on the neuroprotective effects of isoquinoline alkaloids.

Neferine mitigates cisplatin-induced acute kidney injury in mice by regulating autophagy and apoptosis

PURPOSE

The nephrotoxicity caused by cisplatin severely limits the application and affects related platinum-based therapeutics. Neferine is a dibenzylisoquinoline alkaloid extracted from a Chinese medicinal herb (Nelumbo nucifera Gaertn), which can decrease cisplatin-induced apoptosis of NRK-52E cells by activating autophagy in vitro in our previous study. In this article, we aimed to further investigate the protective effect of neferine, against to the cispltain-induced kidney damage in mice.

METHODS

Six groups were designed in our study. Renal index, mice serum creatinine and blood urea nitrogen levels were detected after the mice were killed. HE staining was used to observe the pathological changes of each group. The apoptosis of mouse kidney tissue was detected by TUNEL. Immunofluorescence and Western blot were used to detect the expression of cleaved-caspase3 and LC3. The transmission electron microscope was used to reveal the changes of apoptosis and autophagy of renal tubular epithelial cells in different groups.

RESULTS

In our findings, the pathological changes of acute kidney injury were easily observed in cisplatin-treated mice while those in the neferine-pretreated groups were significantly alleviated. The apoptosis induced by cisplatin in mice increased evidently compared with the control group, which was decreased in the mice with neferine pretreatment. What' more, we found that autophagy increased obviously in mice pretreated by neferine contrast to the cisplatin-treated mice.

CONCLUSION

In our study, neferine can effectively alleviate cisplatin-induced renal injury in mice, as well act as an autophagy-regulator in kidney protection.

Nutraceuticals and phytotherapeutics for holistic management of amyotrophic lateral sclerosis

Amyotrophic lateral sclerosis" (ALS) is a progressive neuronal disorder that affects sensory neurons in the brain and spinal cord, causing loss of muscle control. Moreover, additional neuronal subgroups as well as glial cells such as microglia, astrocytes, and oligodendrocytes are also thought to play a role in the aetiology. The disease affects upper motor neurons and lowers motor neurons and leads to that either lead to muscle weakness and wasting in the arms, legs, trunk and periventricular area. Oxidative stress, excitotoxicity, programmed cell death, altered neurofilament activity, anomalies in neurotransmission, abnormal protein processing and deterioration, increased inflammation, and mitochondrial dysfunction may all play a role in the progression of ALS. There are presently hardly FDA-approved drugs used to treat ALS, and they are only beneficial in slowing the progression of the disease and enhancing functions in certain individuals with ALS, not really in curing or preventing the illness. These days, researchers focus on understanding the pathogenesis of the disease by targeting several mechanisms aiming to develop successful treatments for ALS. This review discusses the epidemiology, risk factors, diagnosis, clinical features, pathophysiology, and disease management. The compilation focuses on alternative methods for the management of symptoms of ALS with nutraceuticals and phytotherapeutics.

The Emerging Landscape of Natural Small-molecule Therapeutics for Huntington's Disease

Huntington's disease (HD) is a rare and fatal neurodegenerative disorder with no diseasemodifying therapeutics. HD is characterized by extensive neuronal loss and is caused by the inherited expansion of the huntingtin (HTT) gene that encodes a toxic mutant HTT (mHTT) protein having expanded polyglutamine (polyQ) residues. Current HD therapeutics only offer symptomatic relief. In fact, Food and Drug Administration (FDA) approved two synthetic small-molecule VMAT2 inhibitors, tetrabenazine (1) and deutetrabenazine (2), for managing HD chorea and various other diseases in clinical trials. Therefore, the landscape of drug discovery programs for HD is evolving to discover disease- modifying HD therapeutics. Likewise, numerous natural products are being evaluated at different stages of clinical development and have shown the potential to ameliorate HD pathology. The inherent anti-inflammatory and antioxidant properties of natural products mitigate the mHTT-induced oxidative stress and neuroinflammation, improve mitochondrial functions, and augment the anti-apoptotic and pro-autophagic mechanisms for increased survival of neurons in HD. In this review, we have discussed HD pathogenesis and summarized the anti-HD clinical and pre-clinical natural products, focusing on their therapeutic effects and neuroprotective mechanism/s.

The Emerging Landscape of Small-Molecule Therapeutics for the Treatment of Huntington's Disease

Huntington's disease (HD) is a progressive neurodegenerative disorder caused by a CAG repeat expansion in the huntingtin gene (HTT). The new insights into HD's cellular and molecular pathways have led to the identification of numerous potent small-molecule therapeutics for HD therapy. The field of HD-targeting small-molecule therapeutics is accelerating, and the approval of these therapeutics to combat HD may be expected in the near future. For instance, preclinical candidates such as naphthyridine-azaquinolone, AN1, AN2, CHDI-00484077, PRE084, EVP4593, and LOC14 have shown promise for further optimization to enter into HD clinical trials. This perspective aims to summarize the advent of small-molecule therapeutics at various stages of clinical development for HD therapy, emphasizing their structure and design, therapeutic effects, and specific mechanisms of action. Further, we have highlighted the key drivers involved in HD pathogenesis to provide insights into the basic principle for designing promising anti-HD therapeutic leads.

Regulation of mitochondrial dysfunction induced cell apoptosis is a potential therapeutic strategy for herbal medicine to treat neurodegenerative diseases

Neurodegenerative disease is a progressive neurodegeneration caused by genetic and environmental factors. Alzheimer’s disease (AD), Parkinson’s disease (PD), and Huntington’s disease (HD) are the three most common neurodegenerative diseases clinically. Unfortunately, the incidence of neurodegenerative diseases is increasing year by year. However, the current available drugs have poor efficacy and large side effects, which brings a great burden to the patients and the society. Increasing evidence suggests that occurrence and development of the neurodegenerative diseases is closely related to the mitochondrial dysfunction, which can affect mitochondrial biogenesis, mitochondrial dynamics, as well as mitochondrial mitophagy. Through the disruption of mitochondrial homeostasis, nerve cells undergo varying degrees of apoptosis. Interestingly, it has been shown in recent years that the natural agents derived from herbal medicines are beneficial for prevention/treatment of neurodegenerative diseases via regulation of mitochondrial dysfunction. Therefore, in this review, we will focus on the potential therapeutic agents from herbal medicines for treating neurodegenerative diseases via suppressing apoptosis through regulation of mitochondrial dysfunction, in order to provide a foundation for the development of more candidate drugs for neurodegenerative diseases from herbal medicine.

Targeting autophagy in ethnomedicine against human diseases

ETHNOPHARMACOLOGICAL RELEVANCE

In the past five years, ethnopharmacy-based drugs have been increasingly used in clinical practice. It has been reported that hundreds of ethnopharmacy-based drugs can modulate autophagy to regulate physiological and pathological processes, and ethnomedicines also have certain therapeutic effects on illnesses, revealing the important roles of these medicines in regulating autophagy and treating diseases.

AIM OF THE STUDY

This study reviews the regulatory effects of natural products on autophagy in recent years, and discusses their pharmacological effects and clinical applications in the process of diseases. It provides a preliminary literature basis and reference for the research of plant drugs in the regulation of autophagy.

MATERIALS AND METHODS

A comprehensive systematic review in the fields of relationship between autophagy and ethnomedicine in treating diseases from PubMed electronic database was performed. Information was obtained from documentary sources.

RESULTS

We recorded some illnesses associated with autophagy, then classified them into different categories reasonably. Based on the uses of these substances in different researches of diseases, a total of 80 active ingredients or compound preparations of natural drugs were searched. The autophagy mechanisms of these substances in the treatments of divers diseases have been summarized for the first time, we also looked forward to the clinical application of some of them.

CONCLUSIONS

Autophagy plays a key function in lots of illnesses, the regulation of autophagy has become one of the important means to prevent and treat these diseases. About 80 compounds and preparations involved in this review have been proved to have therapeutic effects on related diseases through the mechanism of autophagy. Experiments in vivo and in vitro showed that these compounds and preparations could treat these diseases by regulating autophagy. The typical natural products curcumin and tripterine have powerful roles in regulating autophagy and show good and diversified curative effects.

Extracellular Vesicle Delivery of Neferine for the Attenuation of Neurodegenerative Disease Proteins and Motor Deficit in an Alzheimer’s Disease Mouse Model

Exosomes are nano-extracellular vesicles with diameters ranging from 30 to 150 nm, which are secreted by the cell. With their role in drug cargo loading, exosomes have been applied to carry compounds across the blood–brain barrier in order to target the central nervous system (CNS). In this study, high-purity exosomes isolated by the ultra-high-speed separation method were applied as the natural compound carrier, with the loading efficiency confirmed by UHPLC-MS analysis. Through the optimization of various cargo loading methods using exosomes, this study compared the efficiency of different ways for the separation of exosomes and the exosome encapsulation of natural compounds with increasing molecular weights via extensive in vitro and in vivo efficacy studies. In a pharmacokinetic study, our data suggested that the efficiency of compound’s loading into exosomes is positively correlated to its molecular weight. However, with a molecular weight of greater than 1109 Da, the exosome-encapsulated natural compounds were not able to pass through the blood–brain barrier (BBB). In vitro cellular models confirmed that three of the selected exosome-encapsulated natural compounds—baicalin, hederagenin and neferine—could reduce the level of neurodegenerative disease mutant proteins—including huntingtin 74 (HTT74), P301L tau and A53T α-synuclein (A53T α-syn)—more effectively than the compounds alone. With the traditional pharmacological role of the herbal plant Nelumbo nucifera in mitigating anxiety, exosome-encapsulated-neferine was, for the first time, reported to improve the motor deficits of APP/PS1 (amyloid precursor protein/ presenilin1) double transgenic mice, and to reduce the level of β-amyloid (Aβ) in the brain when compared with the same concentration of neferine alone. With the current trend in advocating medicine–food homology and green healthcare, this study has provided a rationale from in vitro to in vivo for the encapsulation of natural compounds using exosomes for the targeting of BBB permeability and neurodegenerative diseases in the future.

Autophagy-Lysosomal Pathway as Potential Therapeutic Target in Parkinson's Disease

Cellular quality control systems have gained much attention in recent decades. Among these, autophagy is a natural self-preservation mechanism that continuously eliminates toxic cellular components and acts as an anti-ageing process. It is vital for cell survival and to preserve homeostasis. Several cell-type-dependent canonical or non-canonical autophagy pathways have been reported showing varying degrees of selectivity with regard to the substrates targeted. Here, we provide an updated review of the autophagy machinery and discuss the role of various forms of autophagy in neurodegenerative diseases, with a particular focus on Parkinson's disease. We describe recent findings that have led to the proposal of therapeutic strategies targeting autophagy to alter the course of Parkinson's disease progression.

Exploring the Role of Autophagy Dysfunction in Neurodegenerative Disorders

Autophagy is a catabolic pathway by which misfolded proteins or damaged organelles are engulfed by autophagosomes and then transported to lysosomes for degradation. Recently, a great improvement has been done to explain the molecular mechanisms and roles of autophagy in several important cellular metabolic processes. Besides being a vital clearance pathway or a cell survival pathway in response to different stresses, autophagy dysfunction, either upregulated or down-regulated, has been suggested to be linked with numerous neurodegenerative disorders like Alzheimer's disease, Parkinson's disease, Huntington's disease, and Amyotrophic lateral sclerosis. Impairment at different stages of autophagy results in the formation of large protein aggregates and damaged organelles, which leads to the onset and progression of different neurodegenerative disorders. This article elucidates the recent progress about the role of autophagy in neurodegenerative disorders and explains how autophagy dysfunction is linked with the pathogenesis of such disorders as well as the novel potential autophagy-associated therapies for treating them.

Plumula Nelumbinis: A review of traditional uses, phytochemistry, pharmacology, pharmacokinetics and safety

ETHNOPHARMACOLOGICAL RELEVANCE

Plumula Nelumbinis, the green embryo of the mature seeds of Nelumbo nucifera Gaertn, has a medical history of over 400 years. It is widely used for clearing the heart and heat, calming the mind, and promoting astringent essence and hemostasis in traditional Chinese medicine. Moreover, it usually dual use as food and medicine. This review aimed to evaluate the therapeutic potential of Plumula Nelumbinis by summarizing its botany, traditional uses, phytochemistry, pharmacology, pharmacokinetics and safety.

METHODS

This review summarized published studies on Plumula Nelumbinis in the Chinese Pharmacopoeia and literature databases including PubMed, Web of Science, Baidu Scholar, Wiley and China Knowledge Resource Integrated Database (CNKI), and limits the different research articles in botany, traditional uses, phytochemistry, pharmacology, pharmacokinetics and safety about Plumula Nelumbinis.

RESULTS

Plumula Nelumbinis is used to treat hypertension, arrhythmia, severe aplastic anemia, insomnia, encephalopathy and gynecological disease in traditional Chinese medicine and clinical studies. More than 130 chemicals have been isolated and identified from Plumula Nelumbinis, including alkaloids, flavonoids, polysaccharides and volatile oil. In addition, pharmacological effects, such as protective effects against cardiovascular diseases, neurological diseases, lung and kidney injury, anti-inflammatory and anticancer activities, were also evaluated by in vitro and in vivo studies. Moreover, the potential signaling pathways regulated by Plumula Nelumbinis in cardiovascular and neurological diseases and perspectives on Plumula Nelumbinis research were discussed.

CONCLUSION

Plumula Nelumbinis, a commonly used Chinese medicine, has a variety of traditional and modern therapeutic uses. Some traditional uses, especially the treatment of cardiovascular and neurological diseases, have been verified by pharmacological investigation. However, the pharmacological molecular mechanisms, pharmacokinetics and toxicology of Plumula Nelumbinis are still incomplete. In the future, a series of systematic studies on active compounds identification, pharmacological mechanism clarification, quality and safety evaluation are necessary.

Protective Effect of Natural Products against Huntington's Disease: An Overview of Scientific Evidence and Understanding Their Mechanism of Action

Huntington's disease (HD), a neurodegenerative disease, normally starts in the prime of adult life, followed by a gradual occurrence of characteristic psychiatric disturbances and cognitive and motor dysfunction. To the best of our knowledge, there is no treatment available to completely mitigate the progression of HD. Among various therapeutic approaches, exhaustive literature reports have confirmed the medicinal benefits of natural products in HD experimental models. Building on this information, this review presents a brief overview of the neuroprotective mechanism(s) of natural products against in vitro/in vivo models of HD. Relevant studies were identified from several scientific databases, including PubMed, ScienceDirect, Scopus, and Google Scholar. After screening through literature from 2005 to the present, a total of 14 medicinal plant species and 30 naturally isolated compounds investigated against HD based on either in vitro or in vivo models were included in the present review. Behavioral outcomes in the HD in vivo model showed that natural compounds significantly attenuated 3-nitropropionic acid (3-NP) induced memory loss and motor incoordination. The biochemical alteration has been markedly alleviated with reduced lipid peroxidation, increased endogenous enzymatic antioxidants, reduced acetylcholinesterase activity, and increased mitochondrial energy production. Interestingly, following treatment with certain natural products, 3-NP-induced damage in the striatum was ameliorated, as seen histologically. Overall, natural products afforded varying degrees of neuroprotection in preclinical studies of HD via antioxidant and anti-inflammatory properties, preservation of mitochondrial function, inhibition of apoptosis, and induction of autophagy.

Molecular Insights into the Multifunctional Role of Natural Compounds: Autophagy Modulation and Cancer Prevention

Autophagy is a vacuolar, lysosomal degradation pathway for injured and damaged protein molecules and organelles in eukaryotic cells, which is controlled by nutrients and stress responses. Dysregulation of cellular autophagy may lead to various diseases such as neurodegenerative disease, obesity, cardiovascular disease, diabetes, and malignancies. Recently, natural compounds have come to attention for being able to modulate the autophagy pathway in cancer prevention, although the prospective role of autophagy in cancer treatment is very complex and not yet clearly elucidated. Numerous synthetic chemicals have been identified that modulate autophagy and are favorable candidates for cancer treatment, but they have adverse side effects. Therefore, different phytochemicals, which include natural compounds and their derivatives, have attracted significant attention for use as autophagy modulators in cancer treatment with minimal side effects. In the current review, we discuss the promising role of natural compounds in modulating the autophagy pathway to control and prevent cancer, and provide possible therapeutic options.

Traditional Chinese medicine compounds regulate autophagy for treating neurodegenerative disease: A mechanism review

Neurodegenerative diseases (NDs) are common chronic diseases related to progressive damage of the nervous system. Globally, the number of people with an ND is dramatically increasing consistent with the fast aging of society and one of the common features of NDs is the abnormal aggregation of diverse proteins. Autophagy is the main process by which misfolded proteins and damaged organelles are removed from cells. It has been found that the impairment of autophagy is associated with many NDs, suggesting that autophagy has a vital role in the neurodegeneration process. Recently, more and more studies have reported that autophagy inducers display a protective role in different ND experimental models, suggesting that enhancement of autophagy could be a potential therapy for NDs. In this review, the evidence for beneficial effects of traditional Chinese medicine (TCM) regulate autophagy in the models of Alzheimer's disease (AD), Parkinson's disease (PD), and other NDs are presented and common autophagy-related mechanisms are identified. The results demonstrate that TCM which regulate autophagy are potential therapeutic candidates for ND treatment.

Autoregulation of JARID2 through PRC2 interaction with its antisense ncRNA

Objective

JARID2 is a member of chromatin-modifying Polycomb Repressive Complex-2 or PRC2. It plays a role in recruiting PRC2 to developmental genes and regulating its activity. JARID2 along with PRC2 is indispensable for normal development. However, it remains unclear how JARID2 expression itself is regulated. Recently a number of non-protein-coding RNAs or ncRNAs are shown to regulate transcription. An antisense ncRNA, JARID2-AS1, is expressed from the first intron of JARID2 isoform-1 but its role in regulation of JARID2 expression has not been investigated. The objective of this study was to explore the role of JARID2-AS1 in regulating JARID2 and consequently PRC2.

Results

We found that JARID2-AS1 is localised in the nucleus and shows anti-correlated expression pattern to that of JARID2 isoform-1 mRNA. More interestingly, data mining approach strongly indicates that JARID2-AS1 binds to PRC2. These are important observations that provide insights into transcriptional regulation of JARID2, especially because they indicate that JARID2-AS1 by interacting and probably recruiting PRC2 participates in an auto-regulatory loop that controls levels of JARID2. This holds importance in regulation of developmental and differentiation processes. However, to support this hypothesis, further in-depth studies are needed which can verify JARID2-AS1-PRC2 interactions.

Lychee seed polyphenol inhibits Aβ-induced activation of NLRP3 inflammasome via the LRP1/AMPK mediated autophagy induction

Emerging evidence indicates that the enhancement of microglial autophagy inhibits the NLRP3 inflammasome mediated neuroinflammation in Alzheimer's disease (AD). Meanwhile, low density lipoprotein receptor-related protein 1 (LRP1) highly expressed in microglia is able to negatively regulate neuroinflammation and positively regulate autophagy. In addition, we have previously reported that an active lychee seed fraction enriching polyphenol (LSP) exhibits anti-neuroinflammation in Aβ-induced BV-2 cells. However, its molecular mechanism of action is still unclear. In this study, we aim to investigate whether LSP inhibits the NLRP3 inflammasome mediated neuroinflammation and clarify its molecular mechanism in Aβ-induced BV-2 cells and APP/PS1 mice. The results showed that LSP dose- and time-dependently activated autophagy by increasing the expression of Beclin 1 and LC3II in BV-2 cells, which was regulated by the upregulation of LRP1 and its mediated AMPK signaling pathway. In addition, both the Western blotting and fluorescence microscopic results demonstrated that LSP could significantly suppress the activation of NLRP3 inflammasome by inhibiting the expression of NLRP3, ASC, the cleavage of caspase-1, and the release of IL-1β in Aβ(1-42)-induced BV-2 cells. In addition, the siRNA LRP1 successfully abolished the effect of LSP on the activation of AMPK and its mediated autophagy, as well as the inhibition of NLRP3 inflammasome. Furthermore, LSP rescued PC-12 cells which were induced by the conditioned medium from Aβ(1-42)-treated BV-2 cells. Moreover, LSP improved the cognitive function and inhibited the NLRP3 inflammasome in APP/PS1 mice. Taken together, LSP inhibited the NLRP3 inflammasome-mediated neuroinflammation in the in vitro and in vivo models of AD, which was closely associated with the LRP1/AMPK-mediated autophagy. Thus, the findings from this study further provide evidences for LSP serving as a potential drug for the treatment of AD in the future.

Acute manganese treatment restores defective autophagic cargo loading in Huntington's disease cell lines

The molecular etiology linking the pathogenic mutations in the Huntingtin (Htt) gene with Huntington's disease (HD) is unknown. Prior work suggests a role for Htt in neuronal autophagic function and mutant HTT protein disrupts autophagic cargo loading. Reductions in the bioavailability of the essential metal manganese (Mn) are seen in models of HD. Excess cellular Mn impacts autophagic function, but the target and molecular basis of these changes are unknown. Thus, we sought to determine if changes in cellular Mn status impact autophagic processes in a wild-type or mutant Htt-dependent manner. We report that the HD genotype is associated with reduced Mn-induced autophagy and that acute Mn exposure increases autophagosome induction/formation. To determine if a deficit in bioavailable Mn is mechanistically linked to the autophagy-related HD cellular phenotypes, we examined autophagosomes by electron microscopy. We observed that a 24 h 100 uM Mn restoration treatment protocol attenuated an established HD 'cargo-recognition failure' in the STHdh HD model cells by increasing the percentage of filled autophagosomes. Mn restoration had no effect on HTT aggregate number, but a 72 h co-treatment with chloroquine (CQ) in GFP-72Q-expressing HEK293 cells increased the number of visible aggregates in a dose-dependent manner. As CQ prevents autophagic degradation this indicates that Mn restoration in HD cell models facilitates incorporation of aggregates into autophagosomes. Together, these findings suggest that defective Mn homeostasis in HD models is upstream of the impaired autophagic flux and provide proof-of-principle support for increasing bioavailable Mn in HD to restore autophagic function and promote aggregate clearance.

Polyphenols isolated from lychee seed inhibit Alzheimer's disease-associated Tau through improving insulin resistance via the IRS-1/PI3K/Akt/GSK-3β pathway

ETHNOPHARMACOLOGICAL RELEVANCE

Lychee seed, the seed of Litchi chinensis Sonn. is one of the commonly used in traditional Chinese medicine (TCM). It possesses many pharmacological effects such as blood glucose and lipid-lowering effects, liver protection, and antioxidation. Our preliminary studies have proven that an active fraction derived from lychee seed (LSF) can significantly decrease the blood glucose level, inhibit amyloid-β (Aβ) fibril formation and Tau hyperphosphorylation, and improve the cognitive function and behavior of Alzheimer's disease (AD) model rats.

AIM OF THE STUDY

The aim of this study was to identify the main active components in LSF that can inhibit the hyperphosphorylation of Tau through improving insulin resistance (IR) in dexamethasone (DXM)-induced HepG2 and HT22 cells.

MATERIALS AND METHODS

The isolation was guided by the bioactivity evaluation of the improvement effect of IR in HepG2 and HT22 cells. The mRNA and protein expressions of IRS-1, PI3K, Akt, GSK-3β, and Tau were measured by RT-PCR, Western blotting, and immunofluorescence methods, respectively.

RESULTS

After extraction, isolation, and elucidation using chromatography and spectrum technologies, three polyphenols including catechin, procyanidin A1 and procyanidin A2 were identified from fractions 3, 5, and 9 derived from LSF. These polyphenols inhibit hyperphosphorylated Tau via the up-regulation of IRS-1/PI3K/Akt and down-regulation of GSK-3β. Molecular docking result further demonstrate that these polyphenols exhibit good binding property with insulin receptor.

CONCLUSIONS

catechin, procyanidin A1, and procyanidin A2 are the main components in LSF that inhibit Tau hyperphosphorylation through improving IR via the IRS-1/PI3K/Akt/GSK-3β pathway. Therefore, the findings in the current study provide novel insight into the anti-AD mechanism of the components in LSF derived from lychee seed, which is valuable for the further development of a novel drug or nutrient supplement for the prevention and treatment of AD.

Neferine and lianzixin extracts have protective effects on undifferentiated caffeine-damaged PC12 cells

BACKGROUND

The embryos of Nelumbo nucifera Gaertn seeds, lianzixin, are used in China as food and traditional herbal medicine. Principal therapeutic indications are insomnia, anxiety and pyrexia. Caffeine is a psychostimulant and excessive use predisposes to cell damage and neurotoxicity. We aimed to investigate the potential protect effect of Neferine and lianzixin extracts on undifferentiated caffeine-damaged phaeochromocytoma cells (PC12 cells).

METHODS

A cell damage model based on undifferentiated PC12 was established with caffeine. Effect of Lianzixin extracts (total alkaloids, alcohol extract and water extract) and neferine on caffeine-damaged PC12 cells was evaluated. Cell viability was assessed using the methyl thiazolyl tetrazolium (MTT) assay, cellular morphology by inverted microscope, the nucleus by Hoechst 33342 staining and cleaved poly ADP-ribose polymerase (PARP) expression by western blot analysis.

RESULTS

Lianzixin extracts (total alkaloids, alcohol extract and water extract) and neferine improved the viability of PC12 cells damaged by caffeine. The morphology of PC12 cells pretreated with neferine, or alcohol or water extract of lianzixin aggregated and attached better than caffeine-damaged cells, but cells pretreated with total alkaloids of lianzixin showed abnormal morphology. Compared with caffeine-damaged cells, cells pretreated with neferine, or alcohol or water extract of lianzixin showed a notable increase in nucleus staining and an obvious decrease in cleaved PARP expression.

CONCLUSIONS

Lianzixin extracts and neferine have protective effects against caffeine-induced damage in PC12 cells, which laid a foundation for finding a new medicine value of Lianzixin.

Escins Isolated from Aesculus chinensis Bge. Promote the Autophagic Degradation of Mutant Huntingtin and Inhibit its Induced Apoptosis in HT22 cells

The pathogenesis of Huntington’s disease (HD), an inherited progressive neurodegenerative disease, is highly associated with the cytotoxicity-inducing mutant huntingtin (mHtt) protein. Emerging evidence indicates that autophagy plays a pivotal role in degrading aggregated proteins such as mHtt to enhance neuronal viability. In this study, by employing preparative high-performance liquid chromatography (pre-HPLC), ultra-high performance liquid chromatography diode-array-detector quadrupole time-of-flight mass spectrometry (UHPLC-DAD-Q-TOF-MS) and nuclear magnetic resonance (NMR), three escins, escin IA (EA), escin IB (EB) and isoescin IA (IEA), were isolated and identified from the seed of Aesculus chinensis Bge. (ACB). After EGFP-HTT74-overexpressing HT22 cells were treated with EA, EB and IEA at safe concentrations, the clearance of mHtt and mHtt-induced apoptosis were investigated by Western blot, immunofluorescence microscopy and flow cytometry methods. In addition, the autophagy induced by these escins in HT22 cells was monitored by detecting GFP-LC3 puncta, P62 and LC3 protein expression. The results showed that EA, EB and IEA could significantly decrease mHtt levels and inhibit its induced apoptosis in HT22 cells. In addition, these three saponins induced autophagic flux by increasing the ratio of RFP-LC3 to GFP-LC3, and by decreasing P62 expression. Among the tested escins, EB displayed the best autophagy induction, which was regulated via both the mTOR and ERK signaling pathways. Furthermore, the degradation of mHtt and the commensurate decrease in its cytotoxic effects by EA, EB and IEA were demonstrated to be closely associated with autophagy induction, which depended on ATG7. In conclusion, we are the first to report that the escins, including EA, EB and IEA are novel autophagy inducers that degrade mHtt and inhibit mHtt-induced apoptosis in vitro and in vivo. As a result of these findings, the triterpenoid saponins in ACB might be considered to be promising candidates for the treatment of HD in the future.

The Cytoprotective and Anti-cancer Potential of Bisbenzylisoquinoline Alkaloids from Nelumbo nucifera

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Natural product therapy has been gaining therapeutic importance against various diseases, including cancer. The failure of chemotherapy due to its associated adverse effects promoted adjunct therapy with natural products. Phytochemicals exert anti-carcinogenic activities through the regulation of various cell signaling pathways such as cell survival, inflammation, apoptosis, autophagy and metastasis. The ‘small molecule-chemosensitizing agents’ from plants induce apoptosis in drug-resistant and host-immune resistant cancer cells in in vitro as well as in vivo models. For example, alkaloids from Nelumbo nucifera, liensinine, isoliensinine and neferine exert the anticancer activity through enhanced ROS generation, activation of MAP kinases, followed by induction of autophagy and apoptotic cell death. Likewise, these alkaloids also exert their cytoprotective action against cerebrovascular stroke/ischemic stroke, diabetes, and chemotherapy-induced cytotoxicity. Therefore, the present review elucidates the pharmacological activities of these bisbenzylisoquinoline alkaloids which include the cytoprotective, anticancer and chemosensitizing abilities against various diseases such as cardiovascular diseases, neurological diseases and cancer.

Neferine induces autophagy-dependent cell death in apoptosis-resistant cancers via ryanodine receptor and Ca2+-dependent mechanism

Resistance of cancer cells to chemotherapy is a significant clinical concern and mechanisms regulating cell death in cancer therapy, including apoptosis, autophagy or necrosis, have been extensively investigated over the last decade. Accordingly, the identification of medicinal compounds against chemoresistant cancer cells via new mechanism of action is highly desired. Autophagy is important in inducing cell death or survival in cancer therapy. Recently, novel autophagy activators isolated from natural products were shown to induce autophagic cell death in apoptosis-resistant cancer cells in a calcium-dependent manner. Therefore, enhancement of autophagy may serve as additional therapeutic strategy against these resistant cancers. By computational docking analysis, biochemical assays, and advanced live-cell imaging, we identified that neferine, a natural alkaloid from Nelumbo nucifera, induces autophagy by activating the ryanodine receptor and calcium release. With well-known apoptotic agents, such as staurosporine, taxol, doxorubicin, cisplatin and etoposide, utilized as controls, neferine was shown to induce autophagic cell death in a panel of cancer cells, including apoptosis-defective and -resistant cancer cells or isogenic cancer cells, via calcium mobilization through the activation of ryanodine receptor and Ulk-1-PERK and AMPK-mTOR signaling cascades. Taken together, this study provides insights into the cytotoxic mechanism of neferine-induced autophagy through ryanodine receptor activation in resistant cancers.

Pou4f3 gene mutation promotes autophagy and apoptosis of cochlear hair cells in cisplatin-induced deafness mice

Pou4f3 plays an important role in the development of hair cells in the inner ear sensory epithelia. Autophagy is related to the auditory damage. However, the role and mechanism of Pou4f3 on drug-induced ototoxicity are incompletely understood. Hence, this study aimed to explore the effects of Pou4f3 on the apoptosis of cochlear hair cells (CHCs) and to explore whether autophagy was involved in this process. The cisplatin was used to produce a loss of CHCs to create a murine model of deafness. The AAV vectors were delivered into the scala media through the lateral wall. Compared with the control mice, the cisplatin-treated mice exhibited significantly enhanced apoptosis and autophagy in the cochleae, accompanied by a notably decreased Pou4f3 levels. Both mutation and knockdown of Pou4f3 promoted the apoptosis- and autophagy-related protein levels, and enhanced the cisplatin-induced levels of apoptosis- and autophagy-related proteins. Furthermore, the autophagy activator rapamycin promoted the apoptosis and autophagy in the cochlea. In addition, the autophagy inhibitor 3-MA overturned the promoting effect of Pou4f3 knockdown on the apoptosis and autophagy. Collectively, in cisplatin-induced deafness mice, the Pou4f3 gene mutation facilitated apoptosis of cochlear hair cells, at least partially, through inducing autophagy.

Novel steroidal saponin isolated from Trillium tschonoskii maxim. exhibits anti-oxidative effect via autophagy induction in cellular and Caenorhabditis elegans models

BACKGROUND

Emerging evidences indicate the important roles of autophagy in anti-oxidative stress, which is closely associated with cancer, aging and neurodegeneration.

OBJECTIVE

In the current study, we aimed to identify autophagy inducers with potent anti-oxidative effect from traditional Chinese medicines (TCMs) in PC-12 cells and C. elegans.

METHODS

The autophagy inducers were extensively screened in our herbal extracts library by using the stable RFP-GFP-LC3 U87 cells. The components with autophagic induction effect in Trillium tschonoskii Maxim. (TTM) was isolated and identified by using the autophagic activity-guided column chromatography and Pre-HPLC technologies, and MS and NMR spectroscopic analysis, respectively. The anti-oxidative effect of the isolated autophagy inducers was evaluated in H₂O₂-induced PC-12 cells and C. elegans models by measuring the viability of PC-12 cells and C. elegans, with quantitation on the ROS level in vitro and in vivo using H₂DCFDA probe.

RESULTS

The total ethanol extract of TTM was found to significantly increase the formation of GFP-LC3 puncta in stable RFP-GFP-LC3 U87 cells. One novel steroidal saponin 1-O-[2,3,4-tri-O-acetyl-α-L-rhamnopyranosyl-(1→2)-4-O-acetyl-α-L-arabinopyranosyl]-21-Deoxytrillenogenin, (Deoxytrillenoside CA, DTCA) and one known steroidal saponin 1-O-[2,3,4-tri-O-acetyl-α-L-rhamnopyranosyl-(1→2)-4-O-acetyl-α-L-arabinopyranosyl]-21-O-acetyl-epitrillenogenin (Epitrillenoside CA, ETCA) were isolated, identified and found to have novel autophagic effect. Both DTCA and ETCA could activate autophagy in PC-12 cells via the AMPK/mTOR/p70S6K signaling pathway in an Atg7-dependent. In addition, DTCA and ETCA could increase the cell viability and decrease the intracellular ROS level in H₂O₂-treated PC-12 cells and C. elegans, and the further study demonstrated that the induced autophagy contributes to their anti-oxidative effect.

CONCLUSION

Our current findings not only provide information on the discovery of novel autophagy activators from TTM, but also confirmed the anti-oxidative effect of the components from TTM both in vitro and in vivo.

Polyphyllin VI, a saponin from Trillium tschonoskii Maxim. induces apoptotic and autophagic cell death via the ROS triggered mTOR signaling pathway in non-small cell lung cancer

Non-small cell lung cancer (NSCLC) accounts for approximately 85% of all lung cancers. Our previous studies have proven that Trillium tschonoskii Maxim. (TTM), a traditional Chinese medicine, possesses potent anti-tumor effect. However, the detailed components and molecular mechanism of TTM in anti-NSCLC are still unknown. In the present experiment, polyphyllin VI (PPVI) was successfully isolated from TTM with guidance of the anti-proliferative effect in A549 cells, and the cell death of PPVI treated A549 and H1299 cells was closely linked with the increased intracellular ROS levels. In addition, PPVI induced apoptosis by promoting the protein expression of Bax/Bcl2, caspase-3 and caspase-9, and activated autophagy by improving LC3 II conversion and GFP-LC3 puncta formation in A549 and H1299 cells. The mechanism study found that the activity of mTOR which regulates cell growth, proliferation and autophagy was significantly suppressed by PPVI. Accordingly, the PI3K/AKT and MEK/ERK pathways positively regulating mTOR were inhibited, and AMPK negatively regulating mTOR was activated. In addition, the downstream of mTOR, ULK1 at Ser 757 which downregulates autophagy was inhibited by PPVI. The apoptotic cell death induced by PPVI was confirmed, and it was significantly suppressed by the overexpression of AKT, ERK and mTOR, and the induced autophagic cell death which was depended on the Atg7 was decreased by the inhibitors, such as LY294002 (LY), Bafilomycin A1 (Baf), Compound C (CC) and SBI-0206965 (SBI). Furthermore, the mTOR signaling pathway was regulated by the increased ROS as the initial signal in A549 and H1299 cells. Finally, the anti-tumor growth activity of PPVI in vivo was validated in A549 bearing athymic nude mice. Taken together, our data have firstly demonstrated that PPVI is the main component in TTM that exerts the anti-proliferative effect by inducing apoptotic and autophagic cell death in NSCLC via the ROS-triggered mTOR signaling pathway, and PPVI may be a promising candidate for the treatment of NSCLC in future.

Recent progress in the role of autophagy in neurological diseases

Autophagy (here refers to macroautophagy) is a catabolic pathway by which large protein aggregates and damaged organelles are first sequestered into a double-membraned structure called autophago-some and then delivered to lysosome for destruction. Recently, tremen-dous progress has been made to elucidate the molecular mechanism and functions of this essential cellular metabolic process. In addition to being either a rubbish clearing system or a cellular surviving program in response to different stresses, autophagy plays important roles in a large number of pathophysiological conditions, such as cancer, diabetes, and especially neurodegenerative disorders. Here we review recent progress in the role of autophagy in neurological diseases and discuss how dysregulation of autophagy initiation, autophagosome formation, maturation, and/or au-tophagosome-lysosomal fusion step contributes to the pathogenesis of these disorders in the nervous system.

Plant Extracts and Phytochemicals Targeting α-Synuclein Aggregation in Parkinson's Disease Models

α-Synuclein (α-syn) is a presynaptic protein that regulates the release of neurotransmitters from synaptic vesicles in the brain. α-Syn aggregates, including Lewy bodies, are features of both sporadic and familial forms of Parkinson's disease (PD). These aggregates undergo several key stages of fibrillation, oligomerization, and aggregation. Therapeutic benefits of drugs decline with disease progression and offer only symptomatic treatment. Novel therapeutic strategies are required which can either prevent or delay the progression of the disease. The link between α-syn and the etiopathogenesis and progression of PD are well-established in the literature. Studies indicate that α-syn is an important therapeutic target and inhibition of α-syn aggregation, oligomerization, and fibrillation are an important disease modification strategy. However, recent studies have shown that plant extracts and phytochemicals have neuroprotective effects on α-syn oligomerization and fibrillation by targeting different key stages of its formation. Although many reviews on the antioxidant-mediated, neuroprotective effect of plant extracts and phytochemicals on PD symptoms have been well-highlighted, the antioxidant mechanisms show limited success for translation to clinical studies. The identification of specific plant extracts and phytochemicals that target α-syn aggregation will provide selective molecules to develop new drugs for PD. The present review provides an overview of plant extracts and phytochemicals that target α-syn in PD and summarizes the observed effects and the underlying mechanisms. Furthermore, we provide a synopsis of current experimental models and techniques used to evaluate plant extracts and phytochemicals. Plant extracts and phytochemicals were found to inhibit the aggregation or fibril formation of oligomers. These also appear to direct α-syn oligomer formation into its unstructured form or promote non-toxic pathways and suggested to be valuable drug candidates for PD and related synucleinopathy. Current evidences from in vitro studies require confirmation in the in vivo studies. Further studies are needed to ascertain their potential effects and safety in preclinical studies for pharmaceutical/nutritional development of these phytochemicals or dietary inclusion of the plant extracts in PD treatment.

Mitochondrial protective effect of neferine through the modulation of nuclear factor erythroid 2-related factor 2 signalling in ischaemic stroke

BACKGROUND AND PURPOSE

Ischaemic stroke is a leading cause of death and long-term disability. Promising neuroprotective compounds are urgently needed to overcome clinical therapeutic limitations. Neuroprotective agents are limited to single-target agents, which further limit their clinical effectiveness. Due to the brain's particular energy requirements, the energy micro-environment, centred in mitochondria, is a new research hotspot in the complex pathology of ischaemic stroke. Here, we studied the effects of neferine (Nef), a bis-benzylisoquinoline alkaloid extracted from the seed embryo of Nelumbo nucifera Gaertn, on ischaemic stroke and its underlying mitochondrial protective mechanisms.

EXPERIMENTAL APPROACH

Rats with permanent middle cerebral artery occlusion (pMCAO)-induced focal cerebral ischaemia and tert-butyl hydroperoxide (t-BHP)-injured PC12 cells were used to investigate the neuroprotective effects of Nef, particularly with regard to energy micro-environment regulation by mitochondria and its mechanism in vivo and in vitro.

KEY RESULTS

Nef protected t-BHP-injured PC12 cells in vitro and ameliorated neurological score, infarct volume, regional cerebral blood flow, cerebral microstructure and oxidant-related enzyme deficits in pMCAO rats in vivo. Nef also prevented mitochondrial dysfunction both in vivo and in vitro. The underlying mechanism of the mitochondrial protective effect of Nef might be attributed to the increased translocation of Nrf2 to the nucleus. Furthermore, the translocation of Nrf2 to nucleus was also decreased by sequestosome 1 (p62) knockdown.

CONCLUSIONS AND IMPLICATIONS

Our results demonstrated that Nef might have therapeutic potential for ischaemic stroke and may exert its protective role through mitochondrial protection. This protection might be attributed to the modulation of Nrf2 signalling.

Polyphenols Derived from Lychee Seed Suppress Aβ (1-42)-Induced Neuroinflammation

Amyloid-β (Aβ) is commonly recognized as the most important factor that results in neuronal cell death and accelerates the progression of Alzheimer’s disease (AD). Increasing evidence suggests that microglia activated by Aβ release an amount of neurotoxic inflammatory cytokines that contribute to neuron death and aggravate AD pathology. In our previous studies, we found that lychee seed fraction (LSF), an active fraction derived from the lychee seed, could significantly improve the cognitive function of AD rats and inhibit Aβ-induced neuroinflammation in vitro, and decrease neuronal injuries in vivo and in vitro. In the current study, we aimed to isolate and identify the specific components in LSF that were responsible for the anti-neuroinflammation effect using preparative high performance liquid chromatography (pre-HPLC), liquid chromatography-mass spectrometry (LC-MS), and nuclear magnetic resonance (NMR) methods. To this end, we confirmed two polyphenols including catechin and procyanidin A2 that could improve the morphological status of BV-2 cells and suppress the release, mRNA levels, and protein expression of pro-inflammatory cytokines such as tumor necrosis factor-α (TNF-α), interleukin-1β (IL-1β), and interleukin-6 (IL-6) through downregulating the nuclear factor-κB (NF-κB) signaling pathway using ELISA, RT-PCR, and Western blotting methods. Furthermore, catechin and procyanidin A2 could inhibit Aβ-induced apoptosis in BV-2 cells by upregulating Bcl-2 and downregulating Bax protein expression. Therefore, the current study illustrated the active substances in lychee seed, and first reported that catechin and procyanidin A2 could suppress neuroinflammation in Aβ-induced BV-2 cells, which provides detailed insights into the molecular mechanism of catechin and procyanidin A2 in the neuroprotective effect, and their further validations of anti-neuroinflammation in vivo is also essential in future research.

Lychee Seed Fraction Inhibits Aβ(1-42)-Induced Neuroinflammation in BV-2 Cells via NF-κB Signaling Pathway

In our previous studies, an active fraction derived from lychee seed could inhibit β-amyloid-induced apoptosis of PC12 cells and neurons. The primarily microglia cells are recognized as the brain’s resident macrophages and thought to remodel of the brain by removing presumably redundant, apoptotic neurons. In the current study, we aimed to investigate the anti-neuroinflammation effect of lychee seed fraction (LSF) in Aβ(1-42)-induced BV-2 cells and the underlying mechanism. The morphology results displayed that LSF could improve the status of Aβ(1-42)-induced BV-2 cells. The enzyme-linked immunosorbent assay, real-time PCR, and Western blotting results showed that LSF could significantly reduce the release, mRNA levels, and protein expressions of the pro-inflammatory cytokines such as interleukin-1β (IL-1β), tumor necrosis factor alpha (TNF-α), cyclooxygenase-2 (COX-2), and inducible nitric oxide synthase (iNOS) in Aβ(1-42)-induced BV-2 cells, which were downregulated through suppressing the NF-κB signaling pathway. Furthermore, LSF could upregulate Bcl-2 and downregulate Bax, Caspase-3, and cleaved-PARP protein expressions. Taken together, our results first demonstrated that LSF could suppress the inflammatory response via inhibiting NF-κB signaling pathway, and inhibit apoptosis in Aβ(1-42)-induced BV-2 cells. Our findings further prove that LSF as a potential drug may be used for treating AD in the future.

Crocin induces autophagic apoptosis in hepatocellular carcinoma by inhibiting Akt/mTOR activity

Background

Autophagy induction is a common mechanism for antitumor chemicals in induction of cancer cell death. However, the role of autophagy in crocin-induced apoptosis is barely studied in hepatocellular carcinoma (HCC).

Materials and methods

The influence of crocin on growth, apoptosis, and autophagy and its mutual relations were analyzed by Cell Counting Kit-8 assay, flow cytometer, EGFP-LC3 puncta analysis, and Western blot in HCC cells. The activities of Akt/mTOR axis and its roles in autophagy regulation were also detected by Western blot in HCC cells treated with crocin. Finally, the roles of Akt/mTOR axis in crocin-induced autophagic apoptosis were analyzed by Western blot and flow cytometer in HCC cells.

Results

The results showed that crocin can induce growth inhibition in a does- and time-dependent pattern by apoptosis. Increased LC3 puncta and upregulated LC3-II accumulation was observed as early as at 6 hours in HepG2 and HCCLM3 cells treated with 3 mg/mL crocin. Moreover, apoptosis analysis using flow cytometer and cleaved poly (ADP-ribose) polymerase detection revealed that autophagy initiation was prior to apoptosis activation in HCC cells treated with crocin. When autophagy was blocked with 3-methyladenine, crocin-induced apoptosis was inhibited in HCC cells. Furthermore, crocin treatment constrained the activities of key proteins in Akt/mTOR signaling, such as p-Akt (S473), p-mTOR (S2448), and p-p70S6K (T389), suggesting that crocin could induce autophagic apoptosis in HCC cells in an Akt/mTOR-dependent mechanism. Indeed, when autophagy was suppressed by forced expression of Akt, the crocin-induced apoptosis was also impaired in HCC cells.

Conclusion

The results suggested that crocin could induce autophagic apoptosis in HCC cells by inhibiting Akt/mTOR activity. This study originally revealed that autophagic apoptosis is a novel cytotoxic function of crocin, which lays the theoretical foundation for clinical application of crocin in HCC.

Chinese Medicine: A Hope for Neurodegenerative Diseases?

With the increase in the proportion of aged population due to the rapid increase of life expectancy, the worldwide prevalence rate of multiple neurodegenerative diseases including Alzheimer's disease, Parkinson's disease, and Huntington's disease has been increased dramatically. The demographic trend toward an older population has drawn the attention to new drug discovery and treatment on age-related diseases. Although a panel of drugs and/or therapies are currently available for treating the neurodegenerative diseases, side effects or insufficient drug efficacy have been reported. With the long history in prescription of Chinese medicine or natural compounds for modulating aged-related diseases, emerging evidence was reported to support the pharmacological role of Chinese medicine in ameliorating the symptoms, or interfering with the pathogenesis of several neurodegenerative diseases. This review brings evidence about today's trends and development of a list of potential neuroprotective herbal compounds from both the traditional and modern pharmacological point of view. With future projections, the potential hope and implication of using Chinese medicine as an alternative source for novel drug discovery for neurodegenerative diseases is proposed.

Natural products as modulator of autophagy with potential clinical prospects

Natural compounds derived from living organisms are well defined for their remarkable biological and pharmacological properties likely to be translated into clinical use. Therefore, delving into the mechanisms by which natural compounds protect against diverse diseases may be of great therapeutic benefits for medical practice. Autophagy, an intricate lysosome-dependent digestion process, with implications in a wide variety of pathophysiological settings, has attracted extensive attention over the past few decades. Hitherto, accumulating evidence has revealed that a large number of natural products are involved in autophagy modulation, either inducing or inhibiting autophagy, through multiple signaling pathways and transcriptional regulators. In this review, we summarize natural compounds regulating autophagy in multifarious diseases including cancer, neurodegenerative diseases, cardiovascular diseases, metabolic diseases, and immune diseases, hoping to inspire further investigation of the underlying mechanisms of natural compounds and to facilitate their clinical use for multiple human diseases.

Pharmacological benefits of neferine - A comprehensive review

This article recapitulates the existing in vitro and in vivo studies focusing on the effects of neferine-an alkaloid derivative of lotus plant, in various disease models and its effects on key signaling molecules. The review also compiles a large number of research studies that demonstrate methods for isolation and extraction, biosynthetic pathway, pharmacological activity and mode of action of neferine and their underlying mechanisms at cellular level. Neferine is a unique bis-benzylisoquinoline alkaloid that possesses a number of therapeutic effects such as anti-cancer, anti-diabetic, anti-aging, anti-microbial, anti-thrombotic, anti-arrhythmic, anti-inflammatory and even anti-HIV. It also enhances the anti-cancer properties of other anti-cancer drugs like cisplatin, adriamycin, taxol, etc. It is also reported to reverse chemo-resistance and enhance sensitivity of the cancer cells towards anti-cancer drugs. The underlying mechanisms for its activities mainly include apoptosis, autophagy and G1 arrest. Neferine protects them against the effect of drugs like cisplatin. The therapeutic properties of neferine is widely diverse, while it shows toxicity to cancer it also shows cyto-protective effects against cardio-vascular diseases, pulmonary disease, and is also effective against Alzheimer's disease and elicits anti-oxidative effect in many cellular systems. This article thus is the first ever attempt to review the therapeutic activities of neferine established in in vitro and in vivo models and to compile all the fragmented data available on the omnipotent activities of neferine.

Targeting Cellular Stress Mechanisms and Metabolic Homeostasis by Chinese Herbal Drugs for Neuroprotection

Traditional Chinese medicine has been practiced for centuries in East Asia. Herbs are used to maintain health and cure disease. Certain Chinese herbs are known to protect and improve the brain, memory, and nervous system. To apply ancient knowledge to modern science, some major natural therapeutic compounds in herbs were extracted and evaluated in recent decades. Emerging studies have shown that herbal compounds have neuroprotective effects or can ameliorate neurodegenerative diseases. To understand the mechanisms of herbal compounds that protect against neurodegenerative diseases, we summarize studies that discovered neuroprotection by herbal compounds and compound-related mechanisms in neurodegenerative disease models. Those compounds discussed herein show neuroprotection through different mechanisms, such as cytokine regulation, autophagy, endoplasmic reticulum (ER) stress, glucose metabolism, and synaptic function. The interleukin (IL)-1β and tumor necrosis factor (TNF)-α signaling pathways are inhibited by some compounds, thus attenuating the inflammatory response and protecting neurons from cell death. As to autophagy regulation, herbal compounds show opposite regulatory effects in different neurodegenerative models. Herbal compounds that inhibit ER stress prevent neuronal death in neurodegenerative diseases. Moreover, there are compounds that protect against neuronal death by affecting glucose metabolism and synaptic function. Since the progression of neurodegenerative diseases is complicated, and compound-related mechanisms for neuroprotection differ, therapeutic strategies may need to involve multiple compounds and consider the type and stage of neurodegenerative diseases.

Neferine, is not inducer but blocker for macroautophagic flux targeting on lysosome malfunction

Neferine, an alkaloid isolated from Lotus seeds, displays multiple pharmacological effects that counter cancer, oxidants, and arrhythmia. It was initially identified as a strong inducer for macroautophagy in cancer cells by suppressing AMPK/mTOR signaling. In this study, we found that autophagy signaling was inhibited in the condition of neferine treatment. Exposure to neferine resulted in the accumulation of LC3-II and an associated adaptor protein, p62/SQSTM1. Knockdown of ATG5 failed to reduce the accumulation of LC3-II induced by neferine. The electron microscopy (EM) images showed that neferine induce accumulation of multi-vesicle bodies (MVB) and failure of lysosome maturation. Moreover, exposure to neferine reduced maturation of cathepsin D and impaired the degradation of autophagic and phagocytic cargos. Rather than stimulate autophagic flux, the data indicate that neferine impaired lysosomes to block degradation within phagolysosomes.

The Medicinal Chemistry of Natural and Semisynthetic Compounds against Parkinson's and Huntington's Diseases

Among the diseases affecting the central nervous system (CNS), neurodegenerations attract the interest of both the clinician and the medicinal chemist. The increasing average age of population, the growing number of patients, and the lack of long-term effective remedies push ahead the quest for novel tools against this class of pathologies. We present a review on the state of the art of the molecules (or combination of molecules) of natural origin that are currently under study against two well-defined pathologies: Parkinson's disease (PD) and Huntington's disease (HD). Nowadays, very few tools are available for preventing or counteracting the progression of such diseases. Two major parameters were considered for the preparation of this review: particular attention was reserved to these research works presenting well-defined molecular mechanisms for the studied compounds, and where available, papers reporting in vivo data were preferred. A literature search for peer-reviewed articles using PubMed, Scopus, and Reaxys databases was performed, exploiting different keywords and logical operators: 91 papers were considered (preferentially published after 2015). The review presents a brief overview on the etiology of the studied neurodegenerations and the current treatments, followed by a detailed discussion of the natural and semisynthetic compounds dividing them in different paragraphs considering their several mechanisms of action.

Tetrandrine, an Activator of Autophagy, Induces Autophagic Cell Death via PKC-α Inhibition and mTOR-Dependent Mechanisms

Emerging evidence suggests the therapeutic role of autophagic modulators in cancer therapy. This study aims to identify novel traditional Chinese medicinal herbs as potential anti-tumor agents through autophagic induction, which finally lead to autophagy mediated-cell death in apoptosis-resistant cancer cells. Using bioactivity-guided purification, we identified tetrandrine (Tet) from herbal plant, Radix stephaniae tetrandrae, as an inducer of autophagy. Across a number of cancer cell lines, we found that breast cancer cells treated with tetrandrine show an increase autophagic flux and formation of autophagosomes. In addition, tetrandrine induces cell death in a panel of apoptosis-resistant cell lines that are deficient for caspase 3, caspase 7, caspase 3 and 7, or Bax-Bak respectively. We also showed that tetrandrine-induced cell death is independent of necrotic cell death. Mechanistically, tetrandrine induces autophagy that depends on mTOR inactivation. Furthermore, tetrandrine induces autophagy in a calcium/calmodulin-dependent protein kinase kinase-β (CaMKK-β), 5' AMP-activated protein kinase (AMPK) independent manner. Finally, by kinase profiling against 300 WT kinases and computational molecular docking analysis, we showed that tetrandrine is a novel PKC-α inhibitor, which lead to autophagic induction through PKC-α inactivation. This study provides detailed insights into the novel cytotoxic mechanism of an anti-tumor compound originated from the herbal plant, which may be useful in promoting autophagy mediated- cell death in cancer cell that is resistant to apoptosis.

Neferine reduces cisplatin-induced nephrotoxicity by enhancing autophagy via the AMPK/mTOR signaling pathway

Cisplatin is one of the most effective chemotherapeutic agents; however, its clinical use is limited by serious side effects of which nephrotoxicity is the most important. Nephrotoxicity induced by cisplatin is closely associated with autophagy reduction and caspase activation. In this study, we investigated whether neferine, an autophagy inducer, had a protective effect against cisplatin-induced nephrotoxicity. In an in vitro cisplatin-induced nephrotoxicity model, we determined that neferine was able to induce autophagy and that pretreatment with neferine not only attenuated cisplatin-induced cell apoptosis but further activated cell autophagy. This pro-survival effect was abolished by the autophagic flux inhibitor chloroquine. Furthermore, neferine pretreatment activated the AMPK/mTOR pathway; however, pharmacological inhibition of AMPK abolished neferine-mediated autophagy and nephroprotection against cisplatin-induced apoptosis. Collectively, our findings suggest for the first time the possible protective mechanism of neferine, which is crucial for its further development as a potential therapeutic agent for cisplatin-induced nephrotoxicity.