Multifunctional nanoliposomes with curcumin-lipid derivative and brain targeting functionality with potential applications for Alzheimer disease

Liposomes loaded with polyphenol-rich grape pomace extracts protect from neurodegeneration in a rotenone-based in vitro model of Parkinson's disease

Parkinson's disease (PD) is a progressive neurodegenerative disease with no satisfactory therapy options. Similar to other neurodegenerative conditions, such as Alzheimer's and Huntington's diseases, oxidative stress plays a key factor in the neurodegeneration process. To counteract the uncontrolled increase of reactive oxygen species (ROS) and oxidative stress-dependent cell death, several preclinical and clinical tests exploit natural-derived organic antioxidants, such as polyphenols. Despite some promising results, free antioxidants show scarce brain accumulation and may exhaust their scavenging activity before reaching the brain. In this work, we developed an antioxidant therapeutic nanoplatform consisting of nano-sized functionalized liposomes loaded with selected polyphenol-rich vegetal extracts with high blood-brain barrier crossing capabilities. The antioxidant extracts were obtained from the grape seeds and skins as a byproduct of wine production (i.e., pomace), following a sustainable circular approach with reduced environmental impact. The antioxidant nanoplatform was successfully tested in a relevant in vitro model of PD, where it completely rescued the ROS levels, prevented the aggregation of α-synuclein fibrils, and restored cell viability, paving the way for preclinical translation of the approach.

Nanoparticle-Guided Brain Drug Delivery: Expanding the Therapeutic Approach to Neurodegenerative Diseases

Neurodegenerative diseases (NDs) represent a heterogeneous group of aging-related disorders featured by progressive impairment of motor and/or cognitive functions, often accompanied by psychiatric disorders. NDs are denoted as 'protein misfolding' diseases or proteinopathies, and are classified according to their known genetic mechanisms and/or the main protein involved in disease onset and progression. Alzheimer's disease (AD), Parkinson's disease (PD) and Huntington's disease (HD) are included under this nosographic umbrella, sharing histopathologically salient features, including deposition of insoluble proteins, activation of glial cells, loss of neuronal cells and synaptic connectivity. To date, there are no effective cures or disease-modifying therapies for these NDs. Several compounds have not shown efficacy in clinical trials, since they generally fail to cross the blood-brain barrier (BBB), a tightly packed layer of endothelial cells that greatly limits the brain internalization of endogenous substances. By engineering materials of a size usually within 1-100 nm, nanotechnology offers an alternative approach for promising and innovative therapeutic solutions in NDs. Nanoparticles can cross the BBB and release active molecules at target sites in the brain, minimizing side effects. This review focuses on the state-of-the-art of nanoengineered delivery systems for brain targeting in the treatment of AD, PD and HD.

Emerging Novel Approaches for the Enhanced Delivery of Natural Products for the Management of Neurodegenerative Diseases

Neurodegenerative diseases (NDs) such as Alzheimer's disease, Parkinson's disease, Huntington disease, amyotrophic lateral sclerosis, and prion disease affect any part of the brain. The complete mechanism of ND is unknown, but there are some molecular mechanism and chemical process. Natural compounds have better compatibility with the human body along with lesser side effects. Moreover, several studies showed that various natural compounds have significant neuroprotective, potent antioxidant, and anti-inflammatory properties, which are effective for treating the different type of ND. In ND, natural compounds act by various mechanisms such as preventing the generation of reactive oxygen species (ROS), eliminating destructed biomolecules before their accumulation affects cell metabolism, and improving the disease conditions. But due to the presence of the blood-brain barrier (BBB) layer and unfavorable pharmacokinetic properties of natural compounds, their delivery into the brain is limited. To minimize this problem and enhance drug delivery into the brain with an effective therapeutic dose, there is a need to develop a practical novel approach. The various studies showed that nanoformulations and microneedles (MN) containing natural compounds such as quercetin, curcumin, resveratrol, chrysin, piperine, ferulic acid, huperzine A, berberine, baicalein, hesperetin, and retinoic acid effectively improved many ND. In this review, the effect of such natural drug-loaded nanoformulation and MN patches on ND management is discussed, along with their merits and demerits. This review aims to introduce different novel approaches for enhancing natural drug delivery into the brain to manage various neurodegenerative diseases.

A comprehensive review on medicinal herbs and novel formulations for the prevention of Alzheimer's disease

Alzheimer's disease (AD) is one of the most prevalent neurodegenerative diseases reported in the aging population across the globe. About 46.8 million people are reported to have dementia, and AD is mainly responsible for dementia in aged people. Alzheimer's disease (AD) is thought to occur due to the accumulation of β-amyloid (Aβ) in the neocortex portion of the brain, nitric oxide mediated dysfunctioning of blood-brain barrier, reduced activity of serine racemase enzyme, cell cycle disturbances, damage of N-methyl-D-aspartate (NMDA) receptors and glutamatergic neurotransmission. Modern treatment methods target the pathways responsible for the disease. To date, solely symptomatic treatments exist for this disease, all making an attempt to counterbalance the neurotransmitter disturbance. Treatments able to prevent or at least effectively modifying the course of AD, referred to as 'disease-modifying' drugs, are still under extensive research. Effective treatments entail a better indulgence of the herbal bioactives by novel drug delivery systems. The herbal bioactive administered by novel drug delivery systems have proved beneficial in treating this disease. This review provides detailed information about the role of medicinal plants and their formulations in treating Alzheimer disease which will be highly beneficial for the researchers working in this area.

Nanomaterials for Modulating the Aggregation of β-Amyloid Peptides

The aberrant aggregation of amyloid-β (Aβ) peptides in the brain has been recognized as the major hallmark of Alzheimer's disease (AD). Thus, the inhibition and dissociation of Aβ aggregation are believed to be effective therapeutic strategiesforthe prevention and treatment of AD. When integrated with traditional agents and biomolecules, nanomaterials can overcome their intrinsic shortcomings and boost their efficiency via synergistic effects. This article provides an overview of recent efforts to utilize nanomaterials with superior properties to propose effective platforms for AD treatment. The underlying mechanismsthat are involved in modulating Aβ aggregation are discussed. The summary of nanomaterials-based modulation of Aβ aggregation may help researchers to understand the critical roles in therapeutic agents and provide new insight into the exploration of more promising anti-amyloid agents and tactics in AD theranostics.

Therapeutic Potential of Phytoconstituents in Management of Alzheimer's Disease

Since primitive times, herbs have been extensively used in conventional remedies for boosting cognitive impairment and age-associated memory loss. It is mentioned that medicinal plants have a variety of dynamic components, and they have become a prominent choice for synthetic medications for the care of cognitive and associated disorders. Herbal remedies have played a major role in the progression of medicine, and many advanced drugs have already been developed. Many studies have endorsed practicing herbal remedies with phytoconstituents, for healing Alzheimer's disease (AD). All the information in this article was collated from selected research papers from online scientific databases, such as PubMed, Web of Science, and Scopus. The aim of this article is to convey the potential of herbal remedies for the prospect management of Alzheimer's and related diseases. Herbal remedies may be useful in the discovery and advancement of drugs, thus extending new leads for neurodegenerative diseases such as AD. Nanocarriers play a significant role in delivering herbal medicaments to a specific target. Therefore, many drugs have been described for the management of age-linked complaints such as dementia, AD, and the like. Several phytochemicals are capable of managing AD, but their therapeutic claims are restricted due to their lower solubility and metabolism. These limitations of natural therapeutics can be overcome by using a targeted nanocarrier system. This article will provide the primitive remedies as well as the development of herbal remedies for AD management.

Experimental and clinical reports on anti-inflammatory, antioxidant, and immunomodulatory effects of Curcuma longa and curcumin, an updated and comprehensive review

Curcuma longa (C. longa) or turmeric is a plant with a long history of use in traditional medicine, especially for treating inflammatory conditions C. longa and its main constituent, curcumin (CUR), showed various pharmacological effects such as antioxidant and anti-microbial properties. The updated knowledge of anti-inflammatory, antioxidant, and immunomodulatory effects of C. longa and CUR is provided in this review article. Pharmacological effects of C. longa, and CUR, including anti-inflammatory, antioxidant, and immunomodulatory properties, were searched using various databases and appropriate keywords until September 2020. Various studies showed anti-inflammatory effects of C. longa and CUR, including decreased white blood cell, neutrophil, and eosinophil numbers, and its protective effects on serum levels of inflammatory mediators such as phospholipase A2 and total protein in different inflammatory disorders. The antioxidant effects of C. longa and CUR were also reported in several studies. The plant extracts and CUR decreased malondialdehyde and nitric oxide levels but increased thiol, superoxide dismutase, and catalase levels in oxidative stress conditions. Treatment with C. longa and CUR also improved immunoglobulin E (Ig)E, pro-inflammatory cytokine interleukin 4 (IL)-4, transforming growth factor-beta, IL-17, interferon-gamma levels, and type 1/type 2 helper cells (Th1)/(Th2) ratio in conditions with disturbance in the immune system. Therefore C. longa and CUR showed anti-inflammatory, antioxidant, and immunomodulatory effects, indicating a potential therapeutic effect of the plant and its constituent, CUR, for treating of inflammatory, oxidative, and immune dysregulation disorders.

Liposome surface modification by phospholipid chemical reactions

Liposomal systems are well known for playing an important role as drug carriers, presenting several therapeutic applications in different sectors, such as in drug delivery, diagnosis, and in many other academic areas. A novel class of this nanoparticle is the actively target liposome, which is constructed with the surface modified with appropriated molecules (or ligands) to actively bind a target molecule of certain cells, system, or tissue. There are many ways to functionalize these nanostructures, from non-covalent adsorption to covalent bond formation. In this review, we focus on the strategies of modifying liposomes by glycerophospholipid covalent chemical reaction. The approach used in this text summarizes the main reactions and strategies used in phospholipid modification that can be carried out by chemists and researchers from other areas. The knowledge of these methodologies is of great importance for planning new studies using this material and also for manipulating its properties.

Contribution of Attenuation of TNF-α and NF-κB in the Anti-Epileptic, Anti-Apoptotic and Neuroprotective Potential of Rosa webbiana Fruit and Its Chitosan Encapsulation

Rosa webbiana L. (Rosaceae) is one of the least reported and most understudied members of this family. It is native to the Himalayan regions of Pakistan and Nepal. The anti-convulsant effect of n-hexane extract of fruit of Rosa webbiana was investigated in a pentylenetetrazole (PTZ)-induced animal model of epilepsy. Male Sprague-Dawley rats were divided into six groups (n = 7) including control, PTZ (40 mg/kg), diazepam (4 mg/kg) and n-hexane extract (at 50, 150 and 300 mg/kg). Convulsive behavior was observed and resultant seizures were scored, animals sacrificed and their brains preserved. Chitosan nanoparticles were prepared using the ionic gelation method and characterized by UV-analysis, zeta potential and Fourier transform infrared spectroscopy (FTIR). The effects of all the treatments on the expression of phosphorylated cytokine tumor necrosis factor α (p-TNF-α) and phosphorylated transcription factor nuclear factor kappa B (p-NF-κB) expression in the cortex and hippocampus of the brains of treated rats were studied through enzyme linked immunosorbent assay (ELISA) and morphological differences and surviving neuronal number were recorded through hematoxylene and eosin (H&E) staining. Significant changes in seizures score and survival rate of rats were observed. Downregulation of neuro-inflammation, p-TNF-α and p-NF-κB was evident. Gas Chromatography-Mass Spectrometry (GC-MS) analysis of this fraction showed multiple constituents of interest, including esters, alkanes and amines.

Nanomedicine: A Promising Way to Manage Alzheimer's Disease

Alzheimer's disease (AD) is a devastating disease of the aging population characterized by the progressive and slow brain decay due to the formation of extracellular plaques in the hippocampus. AD cells encompass tangles of twisted strands of aggregated microtubule binding proteins surrounded by plaques. Delivering corresponding drugs in the brain to deal with these clinical pathologies, we face a naturally built strong, protective barrier between circulating blood and brain cells called the blood-brain barrier (BBB). Nanomedicines provide state-of-the-art alternative approaches to overcome the challenges in drug transport across the BBB. The current review presents the advances in the roles of nanomedicines in both the diagnosis and treatment of AD. We intend to provide an overview of how nanotechnology has revolutionized the approaches used to manage AD and highlight the current key bottlenecks and future perspective in this field. Furthermore, the emerging nanomedicines for managing brain diseases like AD could promote the booming growth of research and their clinical availability.

Impact of curcumin on fatty acid metabolism

Free fatty acids (FFAs) and fatty acid synthesis (FAS) activity have significantly contributed to disease states such as insulin resistance, obesity, type 2 diabetes, myocardial infarction, blood pressure, and several types of cancer. Currently, several treatment options are available for patients with these conditions. Due to safety concerns, adverse effects, limited efficacy, and low tolerability associated with many medications, the identification of novel agents with less toxicity and a more favorable outcome is warranted. Curcumin is a phenolic compound derived from the turmeric plant with various biological activities, including anticarcinogenic, antioxidant, antiinflammatory, and hypolipidemic properties. PubMed, Scopus, and Web of Science were searched up to February 2020 for studies that demonstrated the efficacy and mechanisms of curcumin action on FFAs, FAS, and β-oxidation activity, as well as the desaturation system. Most of the evidence is in-vivo and in-vitro studies that demonstrate that curcumin possesses regulatory properties on FFAs levels through its effects on FAS and β-oxidation activity as well as desaturation system, which could improve insulin resistance, obesity, and other FFAs-related disorders. The present study provides a review of the existing in-vitro, in-vivo, and clinical evidence on the effect of curcumin on FFAs and FAS activity, β-oxidation, and desaturation system.

Nutraceuticals and their Derived Nano-formulations for the Prevention and Treatment of Alzheimer's disease

Alzheimer's disease is one of the common chronic neurological disorders and associated with cognitive dysfunction, depression and progressive dementia. Presence of β-amyloid or senile plaques, hyper-phosphorylated tau proteins, neurofibrillary tangle, oxidative-nitrative stress, mitochondrial dysfunction, endoplasmic reticulum stress, neuroinflammation and derailed neurotransmitter status are the hallmark of AD. Currently, donepezil, memantine, rivastigmine and galantamine are approved by the FDA for symptomatic management. It is well-known that these approved drugs only exert symptomatic relief and possess poor patient-compliance. Additionally, various published evidence shows the neuroprotective potential of various nutraceuticals via their antioxidant, anti-inflammatory and anti-apoptotic effects in the preclinical and clinical studies. These nutraceuticals possess a significant neuroprotective potential and hence, can be a future pharmacotherapeutic for the management and treatment of AD. However, nutraceutical suffers from certain major limitations such as poor solubility, low bioavailability, low stability, fast hepatic-metabolism and larger particle size. These pharmacokinetic attributes restrict their entry into the brain via the blood-brain barrier. Therefore, to over such issues, various nanoformulation of nutraceuticals was developed, that allows their effective delivery into brain owning to reduced particle size, increased lipophilicity increased bioavailability and avoidance of fast hepatic metabolism. Thus, in this review, we have discussed the etiology of AD, focused on the pharmacotherapeutics of nutraceuticals with preclinical and clinical evidence, discussed pharmaceutical limitation and regulatory aspects of nutraceuticals to ensure safety and efficacy. We further explored the latitude of various nanoformulation of nutraceuticals as a novel approach to overcome the existing pharmaceutical limitation and for effective delivery into the brain.

Targeting Alzheimer's disease with multimodal polypeptide-based nanoconjugates

Alzheimer's disease (AD), the most prevalent form of dementia, remains incurable mainly due to our failings in the search for effective pharmacological strategies. Here, we describe the development of targeted multimodal polypeptide-based nanoconjugates as potential AD treatments. Treatment with polypeptide nanoconjugates bearing propargylamine moieties and bisdemethoxycurcumin or genistein afforded neuroprotection and displayed neurotrophic effects, as evidenced by an increase in dendritic density of pyramidal neurons in organotypic hippocampal culture. The additional conjugation of the Angiopep-2 targeting moiety enhanced nanoconjugate passage through the blood-brain barrier and modulated brain distribution with nanoconjugate accumulation in neurogenic areas, including the olfactory bulb. Nanoconjugate treatment effectively reduced neurotoxic β amyloid aggregate levels and rescued impairments to olfactory memory and object recognition in APP/PS1 transgenic AD model mice. Overall, this study provides a description of a targeted multimodal polyglutamate-based nanoconjugate with neuroprotective and neurotrophic potential for AD treatment.

Critical Review of Lipid-Based Nanoparticles as Carriers of Neuroprotective Drugs and Extracts

The biggest obstacle to the treatment of diseases that affect the central nervous system (CNS) is the passage of drugs across the blood-brain barrier (BBB), a physical barrier that regulates the entry of substances into the brain and ensures the homeostasis of the CNS. This review summarizes current research on lipid-based nanoparticles for the nanoencapsulation of neuroprotective compounds. A survey of studies on nanoemulsions (NEs), nanoliposomes/nanophytosomes and solid lipid nanoparticles (SLNs)/nanostructured lipid carriers (NLCs) was carried out and is discussed herein, with particular emphasis upon their unique characteristics, the most important parameters influencing the formulation of each one, and examples of neuroprotective compounds/extracts nanoencapsulated using these nanoparticles. Gastrointestinal absorption is also discussed, as it may pose some obstacles for the absorption of free and nanoencapsulated neuroprotective compounds into the bloodstream, consequently hampering drug concentration in the brain. The transport mechanisms through which compounds or nanoparticles may cross BBB into the brain parenchyma, and the potential to increase drug bioavailability, are also discussed. Additionally, factors contributing to BBB disruption and neurodegeneration are described. Finally, the advantages of, and obstacles to, conventional and unconventional routes of administration to deliver nanoencapsulated neuroprotective drugs to the brain are also discussed, taking into account the avoidance of first-pass metabolism, onset of action, ability to bypass the BBB and concentration of the drug in the brain.

In vitro and in vivo models for anti-amyloidosis nanomedicines

Amyloid diseases are global epidemics characterized by the accumulative deposits of cross-beta amyloid fibrils and plaques. Despite decades of intensive research, few solutions are available for the diagnosis, treatment, and prevention of these debilitating diseases. Since the early work on the interaction of human β₂-microglobulin and nanoparticles by Linse et al. in 2007, the field of amyloidosis inhibition has gradually evolved into a new frontier in nanomedicine offering numerous interdisciplinary research opportunities, especially for materials, chemistry and biophysics. In this review we summarise, for the first time, the in vitro and in vivo models employed thus far in the field of anti-amyloidosis nanomedicines. Based on this systematic summary, we bring forth the notion that, due to the complex and often overlapping physiopathologies of amyloid diseases, there is a crucial need for the appropriate use of in vitro and in vivo models for validating novel anti-amyloidosis nanomedicines, and there is a crucial need for the development of new animal models that reflect the behavioural, symptomatic and cross-talk hallmarks of amyloid diseases such as Alzheimer's (AD), Parkinson's (PD) diseases and type 2 diabetes (T2DM).

Therapeutic Strategies and Nano-Drug Delivery Applications in Management of Aging Alzheimer's Disease

Alzheimer's disease (AD) is a neurodegenerative disorder in which the death of brain cells causes memory loss and cognitive decline. Existing drugs only suppress symptoms or delay further deterioration but do not address the cause of the disease. In spite of screening numerous drug candidates against various molecular targets of AD, only a few candidates, such as acetylcholinesterase inhibitors, are currently utilized as an effective clinical therapy. Currently, nano-based therapies can make a difference, providing new therapeutic options by helping drugs to cross the blood-brain barrier and enter the brain more effectively. The main aim of this review was to highlight advances in research on the development of nano-based therapeutics for improved treatment of AD.

Curcumin Loaded and Co-loaded Nanosystems: A Review from a Biological Activity Enhancement Perspective

BACKGROUND

Curcumin is a natural phenolic compound exhibiting multiple bioactivities that have been evaluated in vitro, in vivo as well as through clinical studies in humans. Some of them include antimicrobial, antioxidant, anti-inflammatory, and central nervous system protective effects. Further, curcumin is generally recognized as a safe substance because of its low toxicity. However, its molecular structure is susceptible to changes in pH, oxidation, photodegradation, low aqueous solubility, and biotransformation compromising its bioavailability; these drawbacks are successfully addressed through nanotechnology.

OBJECTIVE

The present review systematizes findings on the enhancement of curcumin's beneficial effects when it is loaded and co-loaded into different types of nanosystems covering liposomes, polymeric and solid-lipid nanoparticles, nanostructured lipid carrier, lipid-polymeric hybrids, self- -assembled and protein-based core-shell systems in relation to its antimicrobial, antioxidant, anti-inflammatory and central nervous system protective bioactivities.

CONCLUSION

Curcumin is a versatile molecule capable of exerting antimicrobial, antioxidant, anti- inflammatory, and central nervous system protective effects in an enhanced manner using the possibilities offered by the nanotechnology-based approach. Its enhanced bioactivities are associated with increments in solubility, stability, bioavailability, as well as in improved intracellular uptake and cell internalization. These advantages, in addition to curcumin's low toxicity, indicate the potential of curcumin to be loaded and co-loaded into nanosystems capable of providing a controlled release and targeted administration.

Recent Advances in Nanotherapeutic Interventions for the Treatment of Alzheimer's Disease

Alzheimer's disease (AD), with impairment of learning and memory as the common clinical manifestations, is one of the most challenging diseases affecting individuals, their families and society as a whole. The fact that its prevalence is escalating rapidly, with the total number of AD patients estimated to reach 115.4 million by 2050, has made the disease a very challenging ailment worldwide. Several biological barriers like the bloodbrain barrier (BBB), drug efflux by P-glycoprotein and the blood-cerebrospinal fluid barrier restrict the delivery of conventional AD drugs to the central nervous system (CNS), thereby limiting their effectiveness. In order to overcome the above physiological barriers, the development of nanomedicines has been extensively explored. The present review provides an insight into the pathophysiology of AD and risk factors associated with AD. Besides, various nanoformulations reported in the literature for the diagnosis and treatments of AD have been classified and summarised. The patented nanoformulations for AD and details of nanoformulations which are in clinical trials are also mentioned. The review would be helpful to researchers and scientific community by providing them with information related to the recent advances in nanointerventions for the diagnosis and treatment of AD, which they can further explore for better management of the disease. However, although the nanotherapeutics for managing AD have been extensively explored, the factors which hinder their commercialisation, the toxicity concern being one of them, need to be addressed so that effective nanotherapeutics for AD can be developed for clinical use.

Liposomes Decorated with 2-(4'-Aminophenyl)benzothiazole Effectively Inhibit Aβ1-42 Fibril Formation and Exhibit in Vitro Brain-Targeting Potential

The potential of 2-benzothiazolyl-decorated liposomes as theragnostic systems for Alzheimer's disease was evaluated in vitro, using PEGylated liposomes that were decorated with two types of 2-benzothiazoles: (i) the unsubstituted 2-benzothiazole (BTH) and (ii) the 2-(4-aminophenyl)benzothiazole (AP-BTH). The lipid derivatives of both BTH-lipid and AP-BTH-lipid were synthesized, for insertion in liposome membranes. Liposomes (LIP) containing three different concentrations of benzothiazoles (5, 10, and 20%) were formulated, and their stability, integrity in the presence of serum proteins, and their ability to inhibit β-amyloid (1-42) (Αβ42) peptide aggregation (by circular dichroism (CD) and thioflavin T (ThT) assay), were evaluated. Additionally, the interaction of some LIP with an in vitro model of the blood-brain barrier (BBB) was studied. All liposome types ranged between 92 and 105 nm, with the exception of the 20% AP-BTH-LIP that were larger (180 nm). The 5 and 10% AP-BTH-LIP were stable when stored at 4 °C for 40 days and demonstrated high integrity in the presence of serum proteins for 7 days at 37 °C. Interestingly, CD experiments revealed that the AP-BTH-LIP substantially interacted with Αβ42 peptides and inhibited fibril formation, as verified by ThT assay, in contrast with the BTH-LIP, which had no effect. The 5 and 10% AP-BTH-LIP were the most effective in inhibiting Αβ42 fibril formation. Surprisingly, the AP-BTH-LIP, especially the 5% ones, demonstrated high interaction with brain endothelial cells and high capability to be transported across the BBB model. Taken together, the current results reveal that the 5% AP-BTH-LIP are of high interest as novel targeted theragnostic systems against AD, justifying further in vitro and in vivo exploitation.

Preparation, optimization and preliminary pharmacokinetic study of curcumin encapsulated turmeric oil microemulsion in zebra fish

The present investigation aimed to develop curcumin loaded turmeric oil microemulsion for brain targeting. An effort has been made to investigate the role of functional components in developing brain targeted formulation which could enhance the bioavailability and uptake of drug in the brain upon oral administration. Preliminary studies like solubility study, emulsification study and construction of the pseudo ternary phase diagram were performed for screening components. The formulation was optimized by using extreme vertices mixture design. The optimized formulation was characterized for appearance, stability to centrifugation, dilution potential, globule size, zeta potential and drug content. Furthermore, ex-vivo permeation in chicken gut sac non everted technique and pharmacokinetic study in adult zebra fishes were carried out. The optimized formulation was found to clear, yellow-colored with the absence of phase separation and precipitation denoted the stability of formulation to centrifugation and dilution. The mean globule size, polydispersity index, zeta potential and drug content was observed as 29.13± 0.12 nm, 0.23 ± 0.01,-12.33 ± 1.37 mV and 99.10±3.91 %, respectively. Ex vivo permeation study revealed 2.41 fold enhancement in the steady-state flux when compared to curcumin solution. Furthermore, optimized formulation showed shorter T_max (5 min) and higher AUC_(0-∞) (7.93 μg/brain*min) compared to the curcumin solution which showed similar T_max and AUC_(0-∞) of 2.78 μg/brain*min after oral administration to zebra fishes revealing 3.97 fold enhancement. The results revealed enhanced ex vivo oral absorption and enhanced in vivo brain pharmacokinetics of curcumin via functional microemulsion in the zebra fish model.

Preparation, characterization, antioxidant evaluation of new curcumin derivatives and effects of forming HSA-bound nanoparticles on the stability and activity

Curcumin (CCM) is a well-known active component, which has been studied extensively in food and medicine field since it showed various activities. However, some serious issues limit its application, for example, the extremely low solubility, stability and bioavailability. In this study, 10 Curcumin derivatives were synthesized and characterized by ¹H NMR, ¹³C NMR and HR-MS, then their antioxidant activity was evaluated. Compound 2 and curcumin were further investigated by preparing HSA-bound nanoparticles (NP-2 and NP-CCM) to surmount the difficulties mentioned above. The nanoparticles obtained were about 110 nm in size measured by Dynamic light scattering (DLS), the stability of compound 2 in NP-2 was significantly increased. Above all, NP-2 showed more efficient antioxidant and antitumor activity, which was probably attributed to the introduced isopentenyl groups in 2, it was supposed that the isopentenyl groups increased the interaction between compound 2 and HSA. Overall, NP-2 has great potential for some food and pharmaceutical applications.

Recent Advances in Nanotechnology: A Novel Therapeutic System for the Treatment of Alzheimer's Disease

A amyloid-β (Aβ) plaque formation in the brain is known to be the root cause of Alzheimer's disease (AD), which affects the behavior, memory, and cognitive ability in humans. The brain starts undergoing changes several years before the actual appearance of the symptoms. Nanotechnology could prove to be an alternative strategy for treating the disease effectively. It encompasses the diagnosis as well as the therapeutic aspect using validated biomarkers and nano-based drug delivery systems, respectively. A nano-based therapy may provide an alternate strategy, wherein one targets the protofibrillar amyloid-β (Aβ) structures, and this is followed by their disaggregation as random coils. Conventional/routine drug therapies are inefficient in crossing the blood-brain barrier; however, this hurdle can be overcome with the aid of nanoparticles. The present review highlights the various challenges in the diagnosis and treatment of AD. Meticulous and collaborative research using nanotherapeutic systems could provide remarkable breakthroughs in the early-stage diagnosis and therapy of AD.

Nanotechnology to improve the Alzheimer's disease therapy with natural compounds

Alzheimer's disease (AD) is a form of dementia with high impact worldwide, accounting with more than 46 million cases. It is estimated that the number of patients will be four times higher in 2050. The initial symptoms of AD are almost imperceptible and typically involve lapses of memory in recent events. However, the available medicines still focus on controlling the symptoms and do not cure the disease. Regarding the advances in the discovery of new treatments for this devastating disease, natural compounds are gaining increasing relevance in the treatment of AD. Nevertheless, they present some limiting characteristics such as the low bioavailability and the low ability to cross the blood-brain barrier (BBB) that hinder the development of effective therapies. To overcome these issues, the delivery of natural products by targeting nanocarriers has aroused a great interest, improving the therapeutic activity of these molecules. In this article, a review of the research progress on drug delivery systems (DDS) to improve the therapeutic activity of natural compounds with neuroprotective effects for AD is presented. Graphical abstract.

The New Frontiers in Neurodegenerative Diseases Treatment: Liposomal-Based Strategies

In the last decade, the onset of neurodegenerative (ND) diseases is strongly widespread due to the age increase of the world population. Despite the intensive investigations boosted by the scientific community, an efficacious therapy has not been outlined yet. The drugs commonly used are only able to relieve symptom severity; following their oral or intravenous administration routes, their effectiveness is strictly limited due to their low ability to reach the Central Nervous System (CNS) overcoming the Blood Brain Barrier (BBB). Starting from these assumptions, the engineered-nanocarriers, such as lipid-nanocarriers, are suitable agents to enhance the delivery of drugs into the CNS due to their high solubility, bioavailability, and stability. Liposomal delivery systems are considered to be the ideal carriers, not only for conventional drugs but also for neuroprotective small molecules and green-extracted compounds. In the current work, the LP-based drug delivery improvements in in vivo applications against ND disorders were carefully assessed.

Advances in nanomedicines for diagnosis of central nervous system disorders

In spite of a great improvement in medical health services and an increase in lifespan, we have witnessed a skyrocket increase in the incidence of central nervous system (CNS) disorders including brain tumors, neurodegenerative diseases (Alzheimer's disease, Parkinson's disease, amyotrophic lateral sclerosis, Huntington's disease), ischemic stroke, and epilepsy, which have seriously undermined the quality of life and substantially increased economic and societal burdens. Development of diagnostic methods for CNS disorders is still in the early stage, and the clinical outcomes suggest these methods are not ready for the challenges associated with diagnosis of CNS disorders, such as early detection, specific binding, sharp contrast, and continuous monitoring of therapeutic interventions. Another challenge is to overcome various barrier structures during delivery of diagnostic agents, especially the blood-brain barrier (BBB). Fortunately, utilization of nanomaterials has been pursued as a potential and promising strategy to address these challenges. This review will discuss anatomical and functional structures of BBB and transport mechanisms of nanomaterials across the BBB, and special emphases will be placed on the state-of-the-art advances in the development of nanomedicines from a variety of nanomaterials for diagnosis of CNS disorders. Meanwhile, current challenges and future perspectives in this field are also highlighted.

Alzheimer's disease: natural products as inhibitors of neuroinflammation

Alzheimer’s disease (AD) is the most common form of dementia and affects 44 million people worldwide. New emerging evidence from pre-clinical and clinical investigations shows that neuroinflammation is a major pathological component of AD suggesting that anti-inflammatory strategies are important in delaying the onset or slowing the progression of the disease. However, efforts to employ current anti-inflammatory agents in AD clinical trials have produced limited success. Consequently, there is a need to explore anti-inflammatory natural products, which target neuroinflammatory pathways relevant to AD pathogenesis. This review summarises important druggable molecular targets of neuroinflammation and presents classes of anti-neuroinflammatory natural products with potentials for preventing and reducing symptoms of AD.

Impact of nano-conjugate on Drosophila for early diagnosis of Alzheimer's disease

Alzheimer's disease (AD) is an irreversible neurodegenerative disease. Recent identification of AD biomarkers has led to the diagnosis of AD before the onset of dementia. It has been shown that Drosophila melanogaster is a valuable model for studying human neurodegeneration, including AD. According to its properties, curcumin shows promising potential for the diagnosis of AD. In order to improve its use, new formulations, including nanotechnology-based delivery systems, have been applied. The current study aims to diagnose AD by detecting the accumulation of amyloid beta-peptide via carbon-dot-curcumin nanoparticle conjugation in Drosophila. The accumulation of amyloid beta-peptide has been detected via the conjugate using the fluorescence imaging technique. These results suggest that carbon-dot-curcumin nanoparticle conjugation could be used as a diagnostic tool for AD.

Exosome: a significant nano-scale drug delivery carrier

In recent years, due to the limitations of the nature of therapeutic agents, many synthetic nano-delivery systems have emerged to enhance the efficacy of drugs. Extracellular vesicles are currently a class of natural nano-scale drug carriers released by cells. As a tiny vesicle with a lipid bilayer membrane that can be secreted by most cells in the body, exosomes carry and transmit important signal molecules, Therefore, they have been a research hotspot in biomedicine and biomaterials due to their size advantages and huge potential in drug therapy. Many people are optimistic about the clinical application prospects of exosomes and are actively exploring the broad functions of exosomes and developing exosome therapeutic agents to make positive contributions to human health. In this review, we provide basic knowledge and focus on summarizing the advantages of exosomes as drug carriers, methods of loading drugs, targeting strategies, in vivo and in vitro tracing methods, and some of the latest developments in exosomes as drug carriers. In particular, the review provides an outlook for this field.

Nanotechnology: A Promising Approach for Delivery of Neuroprotective Drugs

Central nervous system (CNS) disorders especially neurodegenerative disorders are the major challenge for public health and demand the great attention of researchers to protect people against them. In past few decades, different treatment strategies have been adopted, but their therapeutic efficacy are not enough and have only shown partial mitigation of symptoms. Blood-brain barrier (BBB) and blood-cerebrospinal fluid barrier (BSCFB) guard the CNS from harmful substances and pose as the major challenges in delivering drugs into CNS for treatment of CNS complications such as Alzheimer’s disease (AD), Parkinson’s disease (PD), Huntington’s disease (HD), stroke, epilepsy, brain tumors, multiple sclerosis (MS), and encephalitis, etc. Nanotechnology has come out as an exciting and promising new platform of treating neurological disorders and has shown great potential to overcome problems related to the conventional treatment approaches. Molecules can be nanoengineered to carry out multiple specific functions such as to cross the BBB, target specific cell or signaling pathway, respond to endogenous stimuli, and act as a vehicle for gene delivery, support nerve regeneration and cell survival. In present review, the role of nanocarrier systems such as liposomes, micelles, solid lipid nanoparticles (SLNPs), dendrimers, and nanoemulsions for delivery of various neurotherapeutic agents has been discussed, besides this, their mechanism of action, and nanoformulation of different neuroprotective agents like curcumin, edaravone, nerve growth factors in CNS disorders like Alzheimer’s, Parkinsonism, epilepsy, stroke, and brain tumors has been reviewed.

Recent advances in encapsulation of curcumin in nanoemulsions: A review of encapsulation technologies, bioaccessibility and applications

Curcumin is widely acknowledged for its beneficial activities. However, its application has remained challenging due to its low aqueous solubility, biochemical/structural degradation and poor bioavailability. For these reasons, many researches are aimed at overcoming these limitations using lipid-based nanosystems to encapsulate curcumin, especially nanoemulsions. This review highlights the theoretical aspects and recent advances of preparation technologies (phase inversion temperature, phase inversion composition, ultrasonication, high pressure homogenization and microfluidization) for encapsulation of curcumin in nanoemulsions. Additionally, the specific factors in designing nanoemulsions systems that affect the chemical stability and in vitro bioaccessibility of the encapsulated curcumin are discussed. Also, the importance of nanoemulsions in improving antioxidant, anti-inflammatory and anticancer activities of curcumin is underlined. Curcumin-loaded nanoemulsions preparation technologies have been proposed to provide efficient, systematic, and practical protocols for improved applications of curcumin. Additionally, key factors that influence curcumin delivery include the nature of emulsifier, the type and the amount of carrier oil and emulsifier-curcumin interactions. The pharmacological activities of curcumin including antioxidant, anti-inflammatory and anticancer activities can be improved by nanoemulsions.

Neurotherapeutic applications of nanomedicine for treating Alzheimer's disease

Alzheimer's disease (AD) is a progressive, irreversible, fatal brain disease which disturbs cognitive functions. It affects 35 million people worldwide and the number of people suffering may increase to 100 million by 2050 if no effective treatments are available. The present treatment improves cognitive functions and provide temporary symptomatic relief, but do not stop or delay the disease progression. Moreover, they are mainly available as conventional oral dosage forms and these conventional oral medications lack brain specificity and also produce side effects which leads to poor patient compliance. Brain drug targeting by nanomedicines is a promising approach to improve brain targeting specificity, brain bioavailability and patient compliance. The present review discuses about the currently available pharmacotherapy for AD and the neurotherapeutic applications as well as the advancements of nanomedicine for treating AD. It also highlights the recent advancements of various nanomedicines containing phytopharmaceuticals for treating AD. It is believed that nanomedicines containing approved drugs can be transformed into the clinics hence improve the life style of AD patients.

Nanoformulations of Herbal Extracts in Treatment of Neurodegenerative Disorders

Nanotechnology is one of the methods that influenced human life in different ways and is a substantial approach that assists to overcome the multiple limitations of various diseases, particularly neurodegenerative disorders (NDs). Diverse nanostructures such as polymer nanoparticles, lipid nanoparticles, nanoliposomes, nano-micelles, and carbon nanotubes (CNTs); as well as different vehicle systems including poly lactic-co-glycolic acid, lactoferrin, and polybutylcyanoacrylate could significantly increase the effectiveness, reduce the side effects, enhance the stability, and improve the pharmacokinetics of many drugs. NDs belong to a group of annoying and debilitating diseases that involve millions of people worldwide. Previous studies revealed that several nanoformulations from a number of natural products such as curcumin (Cur), quercetin (QC), resveratrol (RSV), piperine (PIP), Ginkgo biloba, and Nigella sativa significantly improved the condition of patients diagnosed with NDs. Drug delivery to the central nervous system (CNS) has several limitations, in which the blood brain barrier (BBB) is the main drawback for treatment of NDs. This review discusses the effects of herbal-based nanoformulations, their advantages and disadvantages, to manage NDs. In summary, we conclude that herbal-based nano systems have promising proficiency in treatment of NDs, either alone or in combination with other drugs.

Curcumin in Health and Diseases: Alzheimer's Disease and Curcumin Analogues, Derivatives, and Hybrids

Worldwide, Alzheimer’s disease (AD) is the most common neurodegenerative multifactorial disease influencing the elderly population. Nowadays, several medications, among them curcumin, are used in the treatment of AD. Curcumin, which is the principal component of Curcuma longa, has shown favorable effects forsignificantly preventing or treating AD. During the last decade, the scientific community has focused their research on the optimization of therapeutic properties and on the improvement of pharmacokinetic properties of curcumin. This review summarizes bibliographical data from 2009 to 2019 on curcumin analogues, derivatives, and hybrids, as well as their therapeutic, preventic, and diagnostic applications in AD. Recent advances in the field have revealed that the phenolic hydroxyl group could contribute to the anti-amyloidogenic activity. Phenyl methoxy groups seem to contribute to the suppression of amyloid-β peptide (Aβ₄₂) and to the suppression of amyloid precursor protein (APP) andhydrophobic interactions have also revealed a growing role. Furthermore, flexible moieties, at the linker, are crucial for the inhibition of Aβ aggregation. The inhibitory activity of derivatives is increased with the expansion of the aromatic rings. The promising role of curcumin-based compounds in diagnostic imaging is highlighted. The keto-enol tautomerism seems to be a novel modification for the design of amyloid-binding agents. Molecular docking results, (Q)SAR, as well as in vitro and in vivo tests highlight the structures and chemical moieties that are correlated with specific activity. As a result, the knowledge gained from the existing research should lead to the design and synthesis ofinnovative and multitargetedcurcumin analogues, derivatives, or curcumin hybrids, which would be very useful drug and tools in medicine for both diagnosis and treatment of AD.

Role of curcumin and its nanoformulations in neurotherapeutics: A comprehensive review

Curcumin, a dietary polyphenol and major constituent of Curcuma longa (Zingiberaceae), is extensively used as a spice in Asian countries. For ages, turmeric has been used in traditional medicine systems to treat various diseases, which was possible because of its anti-inflammatory, antioxidant, anticancerous, antiepileptic, antidepressant, immunomodulatory, neuroprotective, antiapoptotic, and antiproliferative effects. Curcumin has potent antioxidant, anti-inflammatory, antiapoptotic, neurotrophic activities, which support its plausible neuroprotective effects in neurodegenerative disease. However, there is limited information available regarding the clinical efficacy of curcumin in neurodegenerative cases. The low oral bioavailability of curcumin may be speculated as a plausible factor that limits its effects in humans. Therefore, utilization of several approaches for the enhancement of bioavailability may improve clinical outcomes. Furthermore, the use of nanotechnology and a targeted drug delivery system may improve the bioavailability of curcumin. The present review is designed to summarize the molecular mechanisms pertaining to the neuroprotective effects of curcumin and its nanoformulations.

Curcumin's Nanomedicine Formulations for Therapeutic Application in Neurological Diseases

The brain is the body's control center, so when a disease affects it, the outcomes are devastating. Alzheimer's and Parkinson's disease, and multiple sclerosis are brain diseases that cause a large number of human deaths worldwide. Curcumin has demonstrated beneficial effects on brain health through several mechanisms such as antioxidant, amyloid β-binding, anti-inflammatory, tau inhibition, metal chelation, neurogenesis activity, and synaptogenesis promotion. The therapeutic limitation of curcumin is its bioavailability, and to address this problem, new nanoformulations are being developed. The present review aims to summarize the general bioactivity of curcumin in neurological disorders, how functional molecules are extracted, and the different types of nanoformulations available.

Antioxidants and Nanotechnology: Promises and Limits of Potentially Disruptive Approaches in the Treatment of Central Nervous System Diseases

Many central nervous system (CNS) diseases are still incurable and only symptomatic treatments are available. Oxidative stress is suggested to be a common hallmark, being able to cause and exacerbate the neuronal cell dysfunctions at the basis of these pathologies, such as mitochondrial impairments, accumulation of misfolded proteins, cell membrane damages, and apoptosis induction. Several antioxidant compounds are tested as potential countermeasures for CNS disorders, but their efficacy is often hindered by the loss of antioxidant properties due to enzymatic degradation, low bioavailability, poor water solubility, and insufficient blood-brain barrier crossing efficiency. To overcome the limitations of antioxidant molecules, exploitation of nanostructures, either for their delivery or with inherent antioxidant properties, is proposed. In this review, after a brief discussion concerning the role of the blood-brain barrier in the CNS and the involvement of oxidative stress in some neurodegenerative diseases, the most interesting research concerning the use of nano-antioxidants is introduced and discussed, focusing on the synthesis procedures, functionalization strategies, in vitro and in vivo tests, and on recent clinical trials.

Key for crossing the BBB with nanoparticles: the rational design

Central nervous system diseases are a heavy burden on society and health care systems. Hence, the delivery of drugs to the brain has gained more and more interest. The brain is protected by the blood-brain barrier (BBB), a selective barrier formed by the endothelial cells of the cerebral microvessels, which at the same time acts as a bottleneck for drug delivery by preventing the vast majority of drugs to reach the brain. To overcome this obstacle, drugs can be loaded inside nanoparticles that can carry the drug through the BBB. However, not all particles are able to cross the BBB and a multitude of factors needs to be taken into account when developing a carrier system for this purpose. Depending on the chosen pathway to cross the BBB, nanoparticle material, size and surface properties such as functionalization and charge should be tailored to fit the specific route of BBB crossing.

Molecular mechanisms of curcumin and its analogs in colon cancer prevention and treatment

Colorectal cancer remains to be the most prevalent malignancy in humans and 1.5 million men and women living in the United States are diagnosed with colorectal cancer, with a predicted 145,600 new cases to be diagnosed in 2019. Curcuminoids and its synthetic analogs are now of interest due to their bioactive attributes, especially their action as anticancer activity in various cancer cell line models. Several in vivo and in vitro studies have substantially proved their anticancer activities against colon cancer cell lines. Curcumin analogues like IND-4, FLLL, GO-Y030 and C086 have demonstrated to produce greater cytotoxicity when experimentally studied and study results from many have been suggested to be the same. Combination of curcumin with therapeutic cancer agents like tolfenamic acid, 5-fluorouracil, resveratrol and dasatinib showed improved cytotoxicity and chemotherapeutic effect. The results propose that employment of curcumin with novel drug delivery systems like liposome, micelles and nanoparticle have been performed which could improve the therapeutic efficacy against colon cancer. The present review highlights the mechanism of action, synergistic effect and novel delivery methods to improve the therapeutic potential of curcumin.

Advancements in nanotherapeutics for Alzheimer’s disease: current perspectives

Objectives

Considerable progress has been made in the treatment of Alzheimer’s disease (AD), but all available strategies focus on alleviating symptoms rather than curing, which means that AD is viewed as an unresolvable neurodegenerative disease. Nanotechnological applications offer an alternative platform for the treatment of neurodegenerative diseases. This review aims to summarize the recent nanomedicine and nanotechnology developments for the treatment of AD.

Key findings

A plethora of nanocarriers and nanoparticle prodrugs have been reported to have negligible cytotoxicity in animal models, and these developments have revealed new opportunities for development of new classes of potent drug formulations for AD. Different nanotechnology-based approaches such as polymers, emulsions, lipo-carriers, solid lipid carriers, carbon nanotubes and metal-based carriers have been developed over the past decade, and they have been focusing on both neuroprotective and neurogenerative techniques to treat AD. Studies also reveal that nanotechnological approaches can aid in early diagnosis of AD and enhance therapeutic efficacy and bioavailability.

Summary

Notably, the drugs used conventionally to target the central nervous system have limitations that include an inability to cross the ‘blood–brain barrier’ or the ‘blood–cerebrospinal fluid barrier’ effectively and high drug efflux due to the activity of P-glycoprotein, but these limitations can be successfully overcome when nanocarriers are used for targeted drug delivery in AD.

Curcumin-Loaded Nanostructured Lipid Carrier Modified with Partially Hydrolyzed Ginsenoside

The objective of the present study was to investigate the effect of partially hydrolyzed ginsenoside on the physicochemical properties and in vitro release of curcumin from phospholipid-based nanostructured lipid carrier (NLC). NLC formulas modified with partially hydrolyzed ginsenoside (NLC-PG) were prepared with different amounts of ginsenoside using the conventional hot-melt method. The average particle size of curcumin-loaded NLC-PG ranged from 150 to 200 nm, and polydispersity index was in the range of 0.101-0.177, indicating monodispersed particle size distribution. Optical microscopy showed no sedimentation or recrystallization of curcumin even at 10,000 μg/ml concentration as NLC-PG in distilled water, indicating significantly enhanced solubility. TEM image showed that the nanoparticles were monodispersed with a multilayered core/shell structure. X-ray diffraction and FTIR spectroscopy showed that curcumin was amorphous in the NLC-PG, and there was no interaction between curcumin and the excipients. In vitro release study using simulated gastric/intestinal fluid media revealed that the release rate (J_ss) of curcumin from the NLC-PG increased as a function of the ginsenoside content in the lipid carrier. Moreover, the J_ss of curcumin kept gradually increasing in the presence of lipase, whereas in the presence of viscozyme, it sharply increased until the ginsenoside content reached 9.09% and subsequently plateaued. Partially hydrolyzed ginsenoside increased the J_ss of curcumin from curcumin-loaded NLC-PG and therefore may be useful for improving the bioavailability of curcumin.

Protein-functionalized nanoparticles derived from end-functional polymers and polymer prodrugs for crossing the blood-brain barrier

Nanoparticles may provide a viable way for neuroprotective drugs to cross the blood-brain barrier (BBB), which limits the passage of most drugs from the peripheral circulation to the brain. Heterotelechelic polymer prodrugs comprising a neuroprotective model drug (adenosine) and a maleimide functionality were synthesized by the "drug-initiated" approach and subsequent nitroxide exchange reaction. Nanoparticles were obtained by nanoprecipitation and exhibited high colloidal stability with diameters in the 162-185 nm range and narrow size distributions. Nanoparticles were then covalently surface-conjugated to different proteins (albumin, α2-macroglobulin and fetuin A) to test their capability of enhancing BBB translocation. Their performances in terms of endothelial permeability and cellular uptake in an in vitro BBB model were compared to that of similar nanoparticles with surface-adsorbed proteins, functionalized or not with the drug. It was shown that bare NPs (i.e., NPs not surface-functionalized with proteins) without the drug exhibited significant permeability and cellular uptake, which were further enhanced by NP surface functionalization with α2-macroglobulin. However, the presence of the drug at the polymer chain-end prevented efficient passage of all types of NPs through the BBB model, likely due to adecrease in the hydrophobicity of the nanoparticle surface and alteration of the protein binding/coupling, respectively. These results established a new and facile synthetic approach for the surface-functionalization of polymer nanoparticles for brain delivery purposes.