Natural Product-based Nanomedicine: Recent Advances and Issues for the Treatment of Alzheimer's Disease

Natural polyphenol mangiferin delays neuronal cell senescence by inhibiting neuroinflammation mediated by microglial activation

Extracellular β-amyloid protein (Aβ) plaques are prominent pathological feature of Alzheimer's disease (AD). Aβ oligomers and plaques induce sustained microglial activation via the adenosine monophosphate-activated protein kinase (AMPK)/mammalian target of rapamycin (mTOR)/interferon regulatory factor 5 (IRF5) signaling pathway. This microglial activation-mediated neuroinflammation can accelerate neuronal cell senescence. Consequently, the regulation of the AMPK/mTOR/IRF5 pathway presents a potential therapeutic target for AD, as it may inhibit neuroinflammation and delay neuronal cell senescence. Mangiferin, a bioactive natural polyphenol extracted from the leaves of Mangifera indica Linn., has garnered significant attention for its anti-inflammatory properties. However, it remains unclear whether mangiferin can modulate the AMPK/mTOR/IRF5 pathway to inhibit microglial activation-mediated neuroinflammation and delay neuronal cell senescence. This study employed both cellular and animal models of neuronal cell senescence to explore the effects of mangiferin on the regulation of the AMPK/mTOR/IRF5 pathway, aiming to inhibit neuroinflammation and delay neuronal cell senescence in vitro and in vivo. Specifically, SH-SY5Y neuroblastoma cells were subjected to a neuroinflammatory microenvironment induced by Aβ1-42-mediated HMC3 microglial activation to induce neuronal cell senescence in vitro. Additionally, SAMP8 accelerated aging mice were utilized as an aging animal model. The results indicate that mangiferin significantly enhances AMPK phosphorylation in microglial cells, inhibits mTOR activation, and downregulates IRF5 expression. These effects collectively suppress microglial activation and markedly reduce the production of pro-inflammatory cytokines by activated microglia. Consequently, there is a decrease in the proportion of neurons arrested in the G0/G1 phase and a reduction in the number of senescence-associated β-galactosidase (SA-β-gal) positive neurons. Furthermore, mangiferin significantly decreases the expression of neuronal cell senescence markers P16Ink4a and P21Cip1. Collectively, these findings suggest that mangiferin effectively regulates the AMPK/mTOR/IRF5 pathway, inhibits neuroinflammation mediated by microglial activation, and delays neuronal cell senescence. This study underscores the potential of mangiferin for the treatment of neuroinflammation and neurodegenerative diseases.

Nanomaterials-mediated lysosomal regulation: a robust protein-clearance approach for the treatment of Alzheimer's disease

Alzheimer's disease is a debilitating, progressive neurodegenerative disorder characterized by the progressive accumulation of abnormal proteins, including amyloid plaques and intracellular tau tangles, primarily within the brain. Lysosomes, crucial intracellular organelles responsible for protein degradation, play a key role in maintaining cellular homeostasis. Some studies have suggested a link between the dysregulation of the lysosomal system and pathogenesis of neurodegenerative diseases, including Alzheimer's disease. Restoring the normal physiological function of lysosomes hold the potential to reduce the pathological burden and improve the symptoms of Alzheimer's disease. Currently, the efficacy of drugs in treating Alzheimer's disease is limited, with major challenges in drug delivery efficiency and targeting. Recently, nanomaterials have gained widespread use in Alzheimer's disease drug research owing to their favorable physical and chemical properties. This review aims to provide a comprehensive overview of recent advances in using nanomaterials (polymeric nanomaterials, nanoemulsions, and carbon-based nanomaterials) to enhance lysosomal function in treating Alzheimer's disease. This review also explores new concepts and potential therapeutic strategies for Alzheimer's disease through the integration of nanomaterials and modulation of lysosomal function. In conclusion, this review emphasizes the potential of nanomaterials in modulating lysosomal function to improve the pathological features of Alzheimer's disease. The application of nanotechnology to the development of Alzheimer's disease drugs brings new ideas and approaches for future treatment of this disease.

Mini review of plant products as food supplement against MSG-induced liver injury: antioxidant, oxidative stress and histological prospects

Monosodium glutamate (MSG) is an odorless white solid crystalline derived from the amino acid glutamic acid. It is widely used as a flavor enhancer, but its excessive consumption has been associated with toxicity to various organs. In MSG-induced liver injury, few mechanisms have been identified, which started with the generation of reactive oxygen species that leads to oxidative stress which further causes liver injury. In response to this health concern, there is growing interest in various plant products such as plant extracts, flavonoids and phenolic compounds that were able to minimize oxidative stress, serum transaminases and scavenge free radicals in the liver after MSG administration. This review explores the potential of various plant products as dietary supplements to MSG-induced liver injury, focusing on their antioxidant activities, modulatory effects on liver function markers, and histological outcomes. By compiling this evidence, this review provides insights into their potential as preventive strategies against MSG-related liver toxicity, supporting their inclusion in dietary regimens for the maintenance of liver function.

Green synthesis of nanoparticles using medicinal plants as an eco-friendly and therapeutic potential approach for neurodegenerative diseases: a comprehensive review

Central nervous system disorders impact over 1.5 billion individuals globally, with neurodegenerative diseases such as Alzheimer's, Parkinson's, and Huntington's diseases being particularly prominent. These conditions, often associated with aging, present debilitating symptoms including memory loss and movement difficulties. The growing incidence of neurological disorders, alongside a scarcity of effective anti-amyloidogenic therapies, highlights an urgent need for innovative treatment methodologies. Nanoparticles (NPs), derived from medicinal plants and characterized by their favorable pharmacological properties and minimal side effects, offer a promising solution. Their inherent attributes allow for successful traversal of the blood-brain barrier (BBB), enabling targeted delivery to the brain and the modulation of specific molecular pathways involved in neurodegeneration. NPs are crucial in managing oxidative stress, apoptosis, and neuroinflammation in ND. This study reviews the efficacy of green-synthesized nanoparticles in conjunction with various medicinal plants for treating neurodegenerative diseases, advocating for further research to refine these formulations for enhanced clinical applicability and improved patient outcomes.

Exploring Curcumin-Loaded Lipid-Based Nanomedicine as Efficient Targeted Therapy for Alzheimer's Diseases

Alzheimer's disease (AD) is a neurological condition currently with 47 million people suffering from it globally. AD might have many reasons such as genetic issues, environmental factors, and Aβ accumulation, which is the biomarker of the disease. Since the primary reason is unknown, there is no targeted treatment at the moment, but ongoing research aims to slow its progression by managing amyloid-beta peptide production rather than symptomatic improvement. Since phytochemicals have been demonstrated to possess antioxidant, anti-inflammatory, and neuroprotective properties, they may target multiple pathological factors and can reduce the risk of the disease. Curcumin, as a phytochemical found in turmeric known for its antioxidant, free radical scavenging properties, and as an antiamyloid in treating AD, has come under investigation. Although its low bioavailability limits its efficacy, a prominent drug delivery system (DDS) is desired to overcome it. Hence, the potency of lipid-based nanoparticles encapsulating curcumin (LNPs-CUR) is considered in this study as a promising DDS. In vivo studies in animal models indicate LNPs-CUR effectively slow amyloid plaque formation, leading to cognitive enhancement and reduced toxicity compared to free CUR. However, a deeper understanding of CUR's pharmacokinetics and safety profile is crucial before LNPs-CUR can be considered as a medicine. Future investigations may explore the combination of NPs with other therapeutic agents to increase their efficacy in AD cases. This review provides the current position of CUR in the AD therapy paradigm, the DDS suggestions for CUR, and the previous research from the point of analytical view focused on the advantages and challenges.

Natural-product-based, carrier-free, noncovalent nanoparticles for tumor chemo-photodynamic combination therapy

Cancer, with its diversity, heterogeneity, and complexity, is a significant contributor to global morbidity, disability, and mortality, highlighting the necessity for transformative treatment approaches. Photodynamic therapy (PDT) has aroused continuous interest as a viable alternative to conventional cancer treatments that encounter drug resistance. Nanotechnology has brought new advances in medicine and has shown great potential in drug delivery and cancer treatment. For precise and efficient therapeutic utilization of such a tumor therapeutic approach with high spatiotemporal selectivity and minimal invasiveness, the carrier-free noncovalent nanoparticles (NPs) based on chemo-photodynamic combination therapy is essential. Utilizing natural products as the foundation for nanodrug development offers unparalleled advantages, including exceptional pharmacological activity, easy functionalization/modification, and well biocompatibility. The natural-product-based, carrier-free, noncovalent NPs revealed excellent synergistic anticancer activity in comparison with free photosensitizers and free bioactive natural products, representing an alternative and favorable combination therapeutic avenue to improve therapeutic efficacy. Herein, a comprehensive summary of current strategies and representative application examples of carrier-free noncovalent NPs in the past decade based on natural products (such as paclitaxel, 10-hydroxycamptothecin, doxorubicin, etoposide, combretastatin A4, epigallocatechin gallate, and curcumin) for tumor chemo-photodynamic combination therapy. We highlight the insightful design and synthesis of the smart carrier-free NPs that aim to enhance PDT efficacy. Meanwhile, we discuss the future challenges and potential opportunities associated with these NPs to provide new enlightenment, spur innovative ideas, and facilitate PDT-mediated clinical transformation.

Potential Neuroprotective Role of Neurotrophin in Traumatic Brain Injury

Traumatic brain injury (TBI) is a major global health issue that affects millions of people every year. It is caused by any form of external force, resulting in temporary or permanent impairments in the brain. The pathophysiological process following TBI usually involves excitotoxicity, mitochondrial dysfunction, oxidative stress, inflammation, ischemia, and apoptotic cell death. It is challenging to find treatment for TBI due to its heterogeneous nature, and no therapeutic interventions have been approved thus far. Neurotrophins may represent an alternative approach for TBI treatment because they influence various functional activities in the brain. The present review highlights recent studies on neurotrophins shown to possess neuroprotective roles in TBI. Neurotrophins, specifically brain-derived neurotrophic factor (BDNF) and nerve growth factor (NGF) have demonstrated reduced neuronal death, alleviated neuroinflammatory responses and improved neurological functions following TBI via their immunomodulatory, anti-inflammatory and antioxidant properties. Further studies are required to ensure the efficacy and safety of neurotrophins to be used as TBI treatment in clinical settings.

A Chiral Nanocomplex for Multitarget Therapy to Alleviate Neuropathology and Rescue Alzheimer's Cognitive Deficits

Alzheimer's disease (AD) is a severe neurodegenerative condition characterized by inflammation, beta-amyloid (Aβ) plaques, and neurodegeneration, which currently lack effective treatments. Chiral nanomaterials have emerged as a promising option for treating neurodegenerative disorders due to their high biocompatibility, strong sustained release ability, and specific enantiomer selectivity. The development of a stimulus-responsive chiral nanomaterial, UiO-66-NH2 @l-MoS2 QDs@PA-Ni (MSP-U), for the treatment of AD is reported. MSP-U is found to stimulate neural stem cell (NSCs) differentiation, promote in situ hydrogen (H2 ) production, and clear Aβ plaques. l-MoS2 QDs modified with l-Cysteine (l-Cys) effectively enhance the differentiation of NSCs into neurons through circularly polarized near-infrared radiation. Doped-phytic acid nickel (PA-Ni) improves the activity of l-MoS2 QDs in scavenging reactive oxygen species at the lesion site via photocatalytic H2 production. Loading l-MoS2 QDs with UiO-66 type metal oxide suppresses electron-hole recombination effect, thereby achieving rapid charge separation and improving transport of photogenerated electrons, leading to significantly improved H2 production efficiency. The photothermal effect of MSP-U also clears the generated Aβ plaques. In vivo evaluations show that MSP-U improves spatial cognition and memory, suggesting a promising potential candidate for the treatment of AD using chiral nanomaterials.

Research Progress on Natural Plant Molecules in Regulating the Blood-Brain Barrier in Alzheimer's Disease

Alzheimer's disease (AD) is a prevalent neurodegenerative disorder. With the aging population and the continuous development of risk factors associated with AD, it will impose a significant burden on individuals, families, and society. Currently, commonly used therapeutic drugs such as Cholinesterase inhibitors, N-methyl-D-aspartate antagonists, and multiple AD pathology removal drugs have been shown to have beneficial effects on certain pathological conditions of AD. However, their clinical efficacy is minimal and they are associated with certain adverse reactions. Furthermore, the underlying pathological mechanism of AD remains unclear, posing a challenge for drug development. In contrast, natural plant molecules, widely available, offer multiple targeting pathways and demonstrate inherent advantages in modifying the typical pathologic features of AD by influencing the blood-brain barrier (BBB). We provide a comprehensive review of recent in vivo and in vitro studies on natural plant molecules that impact the BBB in the treatment of AD. Additionally, we analyze their specific mechanisms to offer novel insights for the development of safe and effective targeted drugs as well as guidance for experimental research and the clinical application of drugs for the prevention and treatment of AD.

A New Perspective for the Treatment of Alzheimer's Disease: Exosome-like Liposomes to Deliver Natural Compounds and RNA Therapies

With the increment of the aging population in recent years, neurodegenerative diseases exert a major global disease burden, essentially as a result of the lack of treatments that stop the disease progression. Alzheimer's Disease (AD) is an example of a neurodegenerative disease that affects millions of people globally, with no effective treatment. Natural compounds have emerged as a viable therapy to fill a huge gap in AD management, and in recent years, mostly fueled by the COVID-19 pandemic, RNA-based therapeutics have become a hot topic in the treatment of several diseases. Treatments of AD face significant limitations due to the complex and interconnected pathways that lead to their hallmarks and also due to the necessity to cross the blood-brain barrier. Nanotechnology has contributed to surpassing this bottleneck in the treatment of AD by promoting safe and enhanced drug delivery to the brain. In particular, exosome-like nanoparticles, a hybrid delivery system combining exosomes and liposomes' advantageous features, are demonstrating great potential in the treatment of central nervous system diseases.

Adenosine Improves Mitochondrial Function and Biogenesis in Friedreich's Ataxia Fibroblasts Following L-Buthionine Sulfoximine-Induced Oxidative Stress

Adenosine is a nucleoside that is widely distributed in the central nervous system and acts as a central excitatory and inhibitory neurotransmitter in the brain. The protective role of adenosine in different pathological conditions and neurodegenerative diseases is mainly mediated by adenosine receptors. However, its potential role in mitigating the deleterious effects of oxidative stress in Friedreich's ataxia (FRDA) remains poorly understood. We aimed to investigate the protective effects of adenosine against mitochondrial dysfunction and impaired mitochondrial biogenesis in L-buthionine sulfoximine (BSO)-induced oxidative stress in dermal fibroblasts derived from an FRDA patient. The FRDA fibroblasts were pre-treated with adenosine for 2 h, followed by 12.50 mM BSO to induce oxidative stress. Cells in medium without any treatments or pre-treated with 5 µM idebenone served as the negative and positive controls, respectively. Cell viability, mitochondrial membrane potential (MMP), aconitase activity, adenosine triphosphate (ATP) level, mitochondrial biogenesis, and associated gene expressions were assessed. We observed disruption of mitochondrial function and biogenesis and alteration in gene expression patterns in BSO-treated FRDA fibroblasts. Pre-treatment with adenosine ranging from 0-600 µM restored MMP, promoted ATP production and mitochondrial biogenesis, and modulated the expression of key metabolic genes, namely nuclear respiratory factor 1 (NRF1), transcription factor A, mitochondrial (TFAM), and NFE2-like bZIP transcription factor 2 (NFE2L2). Our study demonstrated that adenosine targeted mitochondrial defects in FRDA, contributing to improved mitochondrial function and biogenesis, leading to cellular iron homeostasis. Therefore, we suggest a possible therapeutic role for adenosine in FRDA.

Zebrafish: A Pharmacological Model for Learning and Memory Research

Learning and memory are essential to organism survival and are conserved across various species, especially vertebrates. Cognitive studies involving learning and memory require using appropriate model organisms to translate relevant findings to humans. Zebrafish are becoming increasingly popular as one of the animal models for neurodegenerative diseases due to their low maintenance cost, prolific nature and amenability to genetic manipulation. More importantly, zebrafish exhibit a repertoire of neurobehaviors comparable to humans. In this review, we discuss the forms of learning and memory abilities in zebrafish and the tests used to evaluate the neurobehaviors in this species. In addition, the pharmacological studies that used zebrafish as models to screen for the effects of neuroprotective and neurotoxic compounds on cognitive performance will be summarized here. Lastly, we discuss the challenges and perspectives in establishing zebrafish as a robust model for cognitive research involving learning and memory. Zebrafish are becoming an indispensable model in learning and memory research for screening neuroprotective agents against cognitive impairment.

Functionalization strategies of polymeric nanoparticles for drug delivery in Alzheimer's disease: Current trends and future perspectives

Alzheimer's disease (AD), the most common form of dementia, is a progressive and multifactorial neurodegenerative disorder whose primary causes are mostly unknown. Due to the increase in life expectancy of world population, including developing countries, AD, whose incidence rises dramatically with age, is at the forefront among neurodegenerative diseases. Moreover, a definitive cure is not yet within reach, imposing substantial medical and public health burdens at every latitude. Therefore, the effort to devise novel and effective therapeutic strategies is still of paramount importance. Genetic, functional, structural and biochemical studies all indicate that new and efficacious drug delivery strategies interfere at different levels with various cellular and molecular targets. Over the last few decades, therapeutic development of nanomedicine at preclinical stage has shown to progress at a fast pace, thus paving the way for its potential impact on human health in improving prevention, diagnosis, and treatment of age-related neurodegenerative disorders, including AD. Clinical translation of nano-based therapeutics, despite current limitations, may present important advantages and innovation to be exploited in the neuroscience field as well. In this state-of-the-art review article, we present the most promising applications of polymeric nanoparticle-mediated drug delivery for bypassing the blood-brain barrier of AD preclinical models and boost pharmacological safety and efficacy. In particular, novel strategic chemical functionalization of polymeric nanocarriers that could be successfully employed for treating AD are thoroughly described. Emphasis is also placed on nanotheranostics as both potential therapeutic and diagnostic tool for targeted treatments. Our review highlights the emerging role of nanomedicine in the management of AD, providing the readers with an overview of the nanostrategies currently available to develop future therapeutic applications against this chronic neurodegenerative disease.