Berberine attenuates axonal transport impairment and axonopathy induced by Calyculin A in N2a cells

Alkaloids as drug leads in Alzheimer's treatment: Mechanistic and therapeutic insights

Alzheimer's disease (AD) has few effective treatment options and continues to be a major global health concern. AD is a neurodegenerative disease that typically affects elderly people. Alkaloids have potential sources for novel drug discovery due to their diverse chemical structures and pharmacological activities. Alkaloids, natural products with heterocyclic nitrogen-containing structures, are considered potential treatments for AD. This review explores the neuroprotective properties of alkaloids in AD, focusing on their ability to regulate pathways such as amyloid-beta aggregation, oxidative stress, synaptic dysfunction, tau hyperphosphorylation, and neuroinflammation. The FDA has approved alkaloids such as acetylcholinesterase inhibitors like galantamine and rivastigmine. This article explores AD's origins, current market medications, and clinical applications of alkaloids in AD therapy. This review explores the development of alkaloid-based drugs for AD, focusing on pharmacokinetics, blood-brain barrier penetration, and potential adverse effects. Future research should focus on the clinical evaluation of promising alkaloids, developing recently discovered alkaloids, and the ongoing search for novel alkaloids for medical treatment. A pharmaceutical option containing an alkaloid may potentially slow down the progression of AD while enhancing its symptoms. This review highlights the potential of alkaloids as valuable drug leads in treating AD, providing a comprehensive understanding of their mechanisms of action and therapeutic implications.

Research progress on pharmacological effects and bioavailability of berberine

Berberine (BBR), a benzylisoquinoline alkaloid obtained from natural medicines such as coptidis rhizoma, has a wide range of pharmacological activities such as protecting the nervous system, protecting the cardiovascular system, anti-inflammatory, antidiabetic, antihyperlipidemic, antitumor, antibacterial, and antidiarrheal. However, factors such as poor solubility, low permeability, P-glycoprotein (P-gp) efflux, and hepatic-intestinal metabolism result in BBR having a low bioavailability (< 1%), which restricts its application in clinical settings. Therefore, improving its bioavailability is a prerequisite for its clinical applications. This review summarizes the various pharmacological effects of BBR and analyzes the main reasons for its poor bioavailability. It introduces methods to improve the bioavailability of BBR through the use of absorption enhancers and P-gp inhibitors, structural modification of BBR, and preparation of BBR salts and cocrystals as well as the development of new formulations and focuses on the bioavailability study of the new formulations of BBR. The research of BBR was also prospected in order to provide reference for the further research of BBR.

Anti-inflammatory, antioxidant, and immunomodulatory effects of Berberis vulgaris and its constituent berberine, experimental and clinical, a review

Berberis vulgaris (B. vulgaris or barberry) is a medicinal plant that has been used for various purposes in traditional medicine. Berberine is one of the main alkaloids isolated from B. vulgaris and other plants. Both B. vulgaris and berberine have shown anti-inflammatory, antioxidant, and immunomodulatory effects in different experimental models and clinical trials. This review aims to summarize the current evidence on the mechanisms and applications of B. vulgaris and berberine in modulating inflammation, oxidative stress, and immune responses. The literature search was performed using PubMed, Scopus, and Google Scholar databases until August 2023. The results indicated that B. vulgaris and berberine could inhibit the production of pro-inflammatory cytokines, such as tumor necrosis factor-alpha (TNF-α), interleukin-1β (IL-1β), interleukin 6 (IL-6), and interleukin-17 (IL-17), and enhance the expression of anti-inflammatory cytokines, such as interleukin 10 (IL-10) and transforming growth factor-β (TGF-β), in various cell types and tissues. B. vulgaris and berberine can also scavenge free radicals, increase antioxidant enzymes, such as superoxide dismutase (SOD), catalase (CAT), and glutathione peroxidase (GPx), and reduce lipid peroxidation and DNA damage. B. vulgaris and berberine have been reported to exert beneficial effects in several inflammatory, oxidative, and immune-related diseases, such as diabetes, obesity, cardiovascular diseases, neurodegenerative diseases, autoimmune diseases, allergic diseases, and infections. However, more studies are needed to elucidate the optimal doses, safety profiles, and potential interactions of B. vulgaris and berberine with other drugs or natural compounds.

Berberine: A Multi-Target Natural PCSK9 Inhibitor with the Potential to Treat Diabetes, Alzheimer's, Cancer and Cardiovascular Disease

Berberine is a natural product with a wide range of pharmacological effects. It has antimicrobial, anti-cancer, anti-inflammatory, anti-hyperlipidemic, neuroprotective, and cholesterollowering properties, among others. It has been used in traditional Chinese and Ayurvedic medicine for 3000 years and is generally well-tolerated with few side effects. Its main drawback is low oral bioavailability, which has hindered widespread clinical use. However, recent interest has surged with the emergence of evidence that berberine is effective in treating cancer, diabetes, Alzheimer's disease, and cardiovascular disease via multiple mechanisms. It enhances insulin sensitivity and secretion by pancreatic β-cells in Type 2 Diabetes Mellitus in addition to reducing pro-inflammatory cytokines such as IL-6, IL-1β, TLR4 and TNF-α. These cytokines are elevated in Alzheimer's disease, cardiovascular disease, and diabetes. Reductions in pro-inflammatory cytokine levels are associated with positive outcomes such as improved cognition, reduced cardiovascular events, and improved glucose metabolism and insulin sensitivity. Berberine is a natural PCSK9 inhibitor, which contributes to its hypolipidemic effects. It also increases low-density lipoprotein receptor expression, reduces intestinal cholesterol absorption, and promotes cholesterol excretion from the liver to the bile. This translates into a notable decrease in LDL cholesterol levels. High LDL cholesterol levels are associated with increased cardiovascular disease risk. Novel synthetic berberine derivatives are currently being developed that optimize LDL reduction, bioavailability, and other pharmacokinetic properties.

Development of Liposomes That Target Axon Terminals Encapsulating Berberine in Cultured Primary Neurons

Most of the energy in neurons is produced in mitochondria. Mitochondria generate the ATP that is essential for neuronal growth, function, and regeneration. Mitochondrial axonal transport plays a crucial role in maintaining neuronal homeostasis and biological activity. Decreased mitochondrial axonal transport at axon terminals, where the metabolism of substances is likely to be delayed, may contribute to neurological dysfunction. Therefore, regulation of mitochondrial dynamics at axon terminals has attracted considerable interest as a strategy to modulate neuronal function. Nanoparticles may be useful in controlling local mitochondrial dynamics. Nevertheless, there are few reports on the influence of drug delivery that nanoparticles impart on the mitochondrial dynamics in neurons. This paper reports the results of a study using liposomes (LPs) to examine local drug delivery and pharmacological actions on neurons. We tested berberine (BBR), which is an activator of AMP-activated protein kinase (AMPK), to examine the utility of this drug as a cellular energy sensor. Axon terminals targeting LPs were prepared. The amount of axon terminals targeting LPs was increased compared with treatment using cationic LPs. Moreover, axon terminal-targeting LPs increased anterograde transport by about 40% compared with that of either naked BBR or cationic LPs and suppressed axonal retraction. Our findings suggest that local drug delivery to neurons is important for enhancing pharmacological activity in axon terminals.

Neuroprotective potential of berberine in modulating Alzheimer's disease via multiple signaling pathways

Berberine is one of the most important quinoline alkaloids, which has shown numerous pharmacological activities. There are pieces of evidence that berberine serves as a promising substance for treating Alzheimer's disease (AD). Recently, numerous studies on animal models have shown the neuroprotective role of berberine. AD is a complex disease having multiple pathological factors. Berberine restrains the deposition of amyloid plaques and neurofibrillary tangles. Substantial studies have demonstrated that berberine may also exhibit the protective effect against the risk factors associated with AD. This review illustrates the role of berberine in neuroinflammation, oxidative stress and its activity against acetylcholinesterase enzyme. It also focuses on the bioavailability and safety of berberine in AD. However, more investigations are required to explore the bioavailability and safety assessment of berberine and its new perspectives in limiting the AD-related pathogenesis and risk factors. PRACTICAL APPLICATIONS: Current therapeutic measures only provide symptomatic relief against AD by slowing memory loss, resolving thinking problems and behavioral issues. In recent past years, many biological actions and potential therapeutic applications have been observed by berberine particularly in neurological diseases. Berberine has been investigated by various researchers for its activity against AD. This review demonstrates a variety of mechanisms by which berberine imparts its neuroprotective roles and provides the possible mechanism of action of berberine by which it prevents the formation of neurofibrillary tangles and disaggregation of amyloid beta plaques in AD. It also focuses that berberine limits the neuroinflammation and oxidative stress in AD. Pre-clinical aspects of berberine against AD are also discussed. Eventually, a prospect is formulated that berberine might be a therapeutically significant agent for treating and preventing AD.

Protective effects of berberine against MPTP-induced dopaminergic neuron injury through promoting autophagy in mice

Berberine, an isoquinoline alkaloid isolated from Coptis chinensis, has been widely studied for its efficacy in the treatment of neurodegenerative diseases. However, the detailed mechanisms are unknown. In this study, the effects of berberine on 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP)-induced mice model of Parkinson's disease were investigated. We showed that treatment with berberine significantly ameliorates the degeneration of dopaminergic neurons in substantia nigra compacta (SNc) and improves motor impairment in MPTP-treated mice. Berberine also significantly decreased the level of α-synuclein and enhanced the microtubule-associated protein light chain 3 (LC3-II)-associated autophagy in the SN of MPTP-treated mice. Furthermore, adenosine 5'-monophosphate (AMP)-activated protein kinase (AMPK) was activated by berberine. Berberine's actions were abolished by pre-treatment with 3-methyladenine (an autophagy inhibitor) or compound c (an AMPK inhibitor) in the MPP+-treated SH-SY5Y cells. These results suggested that the protective effects of berberine on the toxicity of MPTP could be attributed to berberine-enhanced autophagy via the AMPK dependent pathway.

Dietary phytochemicals that influence gut microbiota: Roles and actions as anti-Alzheimer agents

The last decide has witnessed a growing research interest in the role of dietary phytochemicals in influencing the gut microbiota. On the other hand, recent evidence reveals that dietary phytochemicals exhibit properties of preventing and tackling symptoms of Alzheimer's disease, which is a neurodegenerative disease that has also been linked with the status of the gut microbiota over the last decade. Till now, little serious discussions, however, have been made to link recent understanding of Alzheimer's disease, dietary phytochemicals and the gut microbiota together and to review the roles played by phytochemicals in gut dysbiosis induced pathologies of Alzheimer's disease. Deciphering these connections can provide insights into the development and future use of dietary phytochemicals as anti-Alzheimer drug candidates. This review aims at presenting latest evidence in the modulating role of phytochemicals in the gut microbiota and its relevance to Alzheimer's disease and summarizing the mechanisms behind the modulative activities. Limitations of current research in this field and potential directions will also be discussed for future research on dietary phytochemicals as anti-Alzheimer agents.

Potential of Naturally Derived Alkaloids as Multi-Targeted Therapeutic Agents for Neurodegenerative Diseases

Alkaloids are a class of secondary metabolites that can be derived from plants, fungi and marine sponges. They are widely known as a continuous source of medicine for the management of chronic disease including cancer, diabetes and neurodegenerative diseases. For example, galanthamine and huperzine A are alkaloid derivatives currently being used for the symptomatic management of neurodegenerative disease. The etiology of neurodegenerative diseases is polygenic and multifactorial including but not limited to inflammation, oxidative stress and protein aggregation. Therefore, natural-product-based alkaloids with polypharmacology modulation properties are potentially useful for further drug development or, to a lesser extent, as nutraceuticals to manage neurodegeneration. This review aims to discuss and summarise recent developments in relation to naturally derived alkaloids for neurodegenerative diseases.

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

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

Potential protective roles of phytochemicals on glutamate-induced neurotoxicity: A review

Glutamate, as an essential neurotransmitter, has been thought to have different roles in the central nervous system (CNS), including nerve regeneration, synaptogenesis, and neurogenesis. Excessive glutamate causes an up-regulation of the multiple signaling pathways, including phosphoinositide-3 kinase/protein kinase B (PI3K/Akt), Akt/mammalian target of rapamycin (mTOR) protein, mitogen-activated protein kinase (MAPK)/extracellular signal-regulated kinase (ERK)1/2, and autophagy that are involved in neurodegenerative diseases pathophysiology. There are numerous findings on curcumin, astaxanthin, thymoquinone, and berberine, as natural products, which have outstanding effects in cell signaling far beyond their anti-oxidant activity, considering as a potential therapeutic target for glutamate excitotoxicity. Herein, we address the role of glutamate as a potential target in neurodegenerative diseases and discuss the protective effects of certain phytochemicals on glutamate-induced neurotoxicity.

Humanin protects cortical neurons from calyculin A-induced neurotoxicities by increasing PP2A activity and SOD

BACKGROUND

Humanin (HN) is an extensive neuroprotective peptide. This study aims to investigate the neuroprotective effects of HN on Calyculin A (CA)-induced neurotoxicities in cortical neurons and the underlying mechanism.

METHODS

CA was added into the cultured cortical neurons to induce neurotoxicity. Cortical neurons were preincubated with HN which plays a protective role. 3-(4,5-Dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT), lactate dehydrogenase (LDH), and Calcein-AM were applied to evaluate the neural insults. Caspase 3 signal and Tunnel were performed to test neural apoptosis. Western blot analysis was used to detect the expressions of phosphorylated tau. The corresponding kits were used to measure the contents of malondialdehyde (MDA) and superoxide dismutase (SOD), and the activity of PP2A, respectively.

RESULTS

HN preincubation preserved cell viability, protected the neurons, alleviated oxidative stress, and reserved PP2A activity. It also blocked tau overphosphorylation at Ser199/202, Ser396, and Thr231 sites and protected neurons against CA-induced insults.

CONCLUSION

These results suggest that HN may serve as a potential therapeutic agent to prevent the pathological changes induced by CA via modulating the activity of PP2A and oxidative stress in neurodegenerative diseases.

Berberine: A Plant-derived Alkaloid with Therapeutic Potential to Combat Alzheimer's disease

Berberine (a protoberberine isoquinoline alkaloid) has shown promising pharmacological activities, including analgesic, anti-inflammatory, anticancer, antidiabetic, anti-hyperlipidemic, cardioprotective, memory enhancement, antidepressant, antioxidant, anti-nociceptive, antimicrobial, anti- HIV and cholesterol-lowering effects. It is used in the treatment of the neurodegenerative disorder. It has strong evidence to serve as a potent phytoconstituent in the treatment of various neurodegenerative disorders such as AD. It limits the extracellular amyloid plaques and intracellular neurofibrillary tangles. It has also lipid-glucose lowering ability, hence can be used as a protective agent in atherosclerosis and AD. However, more detailed investigations along with safety assessment of berberine are warranted to clarify its role in limiting various risk factors and AD-related pathologies. This review highlights the pharmacological basis to control oxidative stress, neuroinflammation and protective effect of berberine in AD, which will benefit to the biological scientists in understanding and exploring the new vistas of berberine in combating Alzheimer's disease.

Berberine Alleviates Tau Hyperphosphorylation and Axonopathy-Associated with Diabetic Encephalopathy via Restoring PI3K/Akt/GSK3β Pathway

BACKGROUND

Axonopathy is closely linked to the development of diabetic encephalopathy induced by type II diabetes (T2D). Berberine has been shown to cross the blood-brain barrier and holds promising effect for neuronal damage in diabetes.

OBJECTIVE

The present study investigated the protective effect and the underlying mechanism of berberine on neuronal axonopathy in both in vitro and in vivo models.

METHODS

High glucose/high fat diet and streptozotocin injection-induced T2D rat model was used. Berberine was administered p.o. to T2D rat model for 10 weeks. Morris water maze test, in vivo neuronal tracing, immunohistochemistry, and western blot analysis were performed to evaluate the protective effects of berberine in T2D-induced diabetic encephalopathy rats. Primary cultured neurons were used to further explore the underlying mechanisms in vitro.

RESULTS

Berberine dramatically reduced blood glucose and serum insulin levels and alleviated insulin resistance. Berberine significantly attenuated memory impairment, axonopathy, and tau hyperphosphorylation, and also restored PI3K/Akt/GSK3β signaling pathway in T2D rats. In vitro, berberine induced an increase in the phosphorylation of PI3K/Akt as well as GSK3β in high glucose-treated primary neurons. Furthermore, berberine-induced PI3K/Akt activation also resulted in the dephosphorylation of tau protein, which could improve axonal transport impairment in high glucose-treated primary neurons. Pretreated neurons with LY294002, an inhibitor of PI3K, partially blocked berberine-inhibited tau phosphorylation and berberine-activated PI3K/Akt signaling pathway.

CONCLUSIONS

Berberine exerts the protective effect against cognitive deficits by improving tau hyperphosphorylation and the axonal damage through restoring PI3K/Akt/GSK3β signaling pathway.

Combating Neurodegenerative Diseases with the Plant Alkaloid Berberine: Molecular Mechanisms and Therapeutic Potential

Neurodegenerative diseases are among the most serious health problems affecting millions of people worldwide. Such diseases are characterized by a progressive degeneration and / or death of neurons in the central nervous system. Currently, there are no therapeutic approaches to cure or even halt the progression of neurodegenerative diseases. During the last two decades, much attention has been paid to the neuroprotective and anti-neurodegenerative activities of compounds isolated from natural products with high efficacy and low toxicity. Accumulating evidence indicates that berberine, an isoquinoline alkaloid isolated from traditional Chinese medicinal herbs, may act as a promising anti-neurodegenerative agent by inhibiting the activity of the most important pathogenic enzymes, ameliorating intracellular oxidative stress, attenuating neuroinflammation, triggering autophagy and protecting neurons against apoptotic cell death. This review attempts to summarize the current state of knowledge regarding the therapeutic potential of berberine against neurodegenerative diseases, with a focus on the molecular mechanisms that underlie its effects on Alzheimer's, Parkinson's and Huntington's diseases.

Role of berberine in Alzheimer's disease

Berberine, an important protoberberine isoquinoline alkaloid, has several pharmacological activities, including antimicrobial, glucose- and cholesterol-lowering, antitumoral, and immunomodulatory properties. Substantial studies suggest that berberine may be beneficial to Alzheimer's disease (AD) by limiting the pathogenesis of extracellular amyloid plaques and intracellular neurofibrillary tangles. Increasing evidence has indicated that berberine exerts a protective role in atherosclerosis related to lipid- and glucose-lowering properties, implicating that berberine has the potential to inhibit these risk factors for AD. This review also attempts to discuss the pharmacological basis through which berberine may retard oxidative stress and neuroinflammation to exhibit its protective role in AD. Accordingly, berberine might be considered a potential therapeutic approach to prevent or delay the process of AD. However, more detailed investigations along with a safety assessment of berberine are warranted to clarify the role of berberine in limiting these risk factors and AD-related pathologies.

Plant alkaloids as drug leads for Alzheimer's disease

Alzheimer's disease (AD) is a neurodegenerative illness associated with dementia and is most prevalent among the elderly population. Current medications can only treat symptoms. Alkaloids are structurally diverse and have been an important source of therapeutics for various brain disorders. Two US Food and Drug Administration (FDA)-approved acetylcholinesterase inhibitors for AD, galantamine and rivastigmine, are in fact alkaloids. In addition, clinical trials of four other extensively studied alkaloids-huperzine A, caffeine, nicotine, and indomethacin-have been conducted but do not convincingly demonstrate their clinical efficacy for AD. Interestingly, rhynchophylline, a known neuroprotective alkaloid, was recently discovered by in silico screening as an inhibitor of EphA4, a novel target for AD. Here, we review the pathophysiological mechanisms underlying AD, current treatment strategies, and therapeutic potential of several selected plant alkaloids in AD, highlighting their various drug targets and the key supportive preclinical and clinical studies. Future research should include more rigorous clinical studies of the most promising alkaloids, the further development of recently discovered candidate alkaloids, and the continual search for new alkaloids for relevant drug targets. It remains promising that an alkaloid drug candidate could significantly affect the progression of AD in addition to providing symptomatic relief.

Sweet taste receptor signaling network: possible implication for cognitive functioning

Sweet taste receptors are transmembrane protein network specialized in the transmission of information from special "sweet" molecules into the intracellular domain. These receptors can sense the taste of a range of molecules and transmit the information downstream to several acceptors, modulate cell specific functions and metabolism, and mediate cell-to-cell coupling through paracrine mechanism. Recent reports indicate that sweet taste receptors are widely distributed in the body and serves specific function relative to their localization. Due to their pleiotropic signaling properties and multisubstrate ligand affinity, sweet taste receptors are able to cooperatively bind multiple substances and mediate signaling by other receptors. Based on increasing evidence about the role of these receptors in the initiation and control of absorption and metabolism, and the pivotal role of metabolic (glucose) regulation in the central nervous system functioning, we propose a possible implication of sweet taste receptor signaling in modulating cognitive functioning.