Toward prevention of Alzheimers disease--potential nutraceutical strategies for suppressing the production of amyloid beta peptides

Clearance of extracellular human amyloid-β aggregates in C. elegans by nutraceutical and pharmaceutical interventions

Numerous anti-amyloid therapies have seen recent clinical development and approval, such as the monoclonal antibodies aducanumab and lecanemab. However, in Alzheimer's disease patients, amyloid-β (Aβ) plaques are found embedded in the extracellular matrix and surrounded by collagens, which might hinder these antibodies from targeting the plaques. We reasoned that various different nutraceutical and pharmaceutical agents might induce collagen and extracellular matrix turnover and removal of these collagen-embedded amyloid-β (Aβ) plaques. To address this idea, here, we used a transgenic C. elegans strain, LSD2104 , expressing fluorescent human Aβ 1-42 as an in-vivo model for secreted amyloid aggregation in the extracellular matrix. We performed a screen of various nutraceuticals and pharmaceuticals along with different combinations, and we found that quercetin 350 µM and rifampicin 75 µM successfully cleared the extracellular amyloid plaque burden compared to the 0.2% DMSO control group, with a combination of the two agents producing the maximum effect compared to either drug alone. These results may implicate the exploration of combination therapeutics of nutraceuticals and pharmaceuticals in the clearance of amyloid-β (Aβ) plaques in Alzheimer's disease.

Insights into the Pathophysiology of Alzheimer's Disease and Potential Therapeutic Targets: A Current Perspective

The aging population increases steadily because of a healthy lifestyle and medical advancements in healthcare. However, Alzheimer's disease (AD) is becoming more common and problematic among older adults. AD-related cases show an increasing trend annually, and the younger age population may also be at risk of developing this disorder. AD constitutes a primary form of dementia, an irreversible and progressive brain disorder that steadily damages cognitive functions and the ability to perform daily tasks. Later in life, AD leads to death as a result of the degeneration of specific brain areas. Currently, the cause of AD is poorly understood, and there is no safe and effective therapeutic agent to cure or slow down its progression. The condition is entirely preventable, and no study has yet demonstrated encouraging findings in terms of treatment. Identifying this disease's pathophysiology can help researchers develop safe and efficient therapeutic strategies to treat this ailment. This review outlines and discusses the pathophysiology that resulted in the development of AD including amyloid-β plaques, tau neurofibrillary tangles, neuroinflammation, oxidative stress, cholinergic dysfunction, glutamate excitotoxicity, and changes in neurotrophins level may sound better based on the literature search from Scopus, PubMed, ScienceDirect, and Google Scholar. Potential therapeutic strategies are discussed to provide more insights into AD mechanisms by developing some possible pharmacological agents for its treatment.

Pathological and cognitive changes in patients with type 2 diabetes mellitus and comorbid MCI and protective hypoglycemic therapies: a narrative review

Type 2 diabetes mellitus (T2DM) is becoming a significant health issue worldwide. Many studies support the hypothesis that patients with T2DM have a higher-than-expected incidence of mild cognitive impairment (MCI) than individuals without diabetes. Based on the results from recent studies, MCI might be associated with the effects of T2DM on glucose metabolism and brain atrophy. As a narrative review, we will illuminate pathological and cognitive changes in patients with T2DM and comorbid MCI and protective hypoglycemic therapies. The early abnormal signs of cognition must be elucidated, and extensive investigations are needed to develop improved therapies for use in the clinic.

Flavor Chemistry of Cocoa and Cocoa Products-An Overview

Cocoa originates from beans of the cocoa tree (Theobroma cacao L.) and it is an important commodity in the world and the main ingredient in chocolate manufacture. Its value and quality are related to unique and complex flavors. Bulk cocoas (Forastero type) exhibit strong basic cocoa notes, whereas fine varieties (Criollo, Nacional) show aromatic, floral, or smoother flavor characteristics. About 600 various compounds (alcohols, carboxylic acids, aldehydes, ketones, esters, and pyrazines) have been identified as odor-active components. The specific cocoa aroma arises from complex biochemical and chemical reactions during the postharvest processing of raw beans, and from many influences of the cocoa genotype, chemical make-up of raw seeds, environmental conditions, farming practices, processing, and manufacturing stages. There has been much research on cocoa flavor components. However, the relationships between all chemical components that are likely to play a role in cocoa flavor, their sensory properties, and the sources and mechanisms of flavor formation are not fully understood. This paper provides an overview on cocoa flavor from a compositional and a sensory perspective. The nonvolatile and volatile chemical components of cocoa and chocolate flavor, and their sensory properties correlated to the main influences involved in flavor formation, are reviewed.

The neuroprotective effects of cocoa flavanol and its influence on cognitive performance

Cocoa powder and chocolate contain numerous substances among which there is a quite large percentage of antioxidant molecules, mainly flavonoids, most abundantly found in the form of epicatechin. These substances display several beneficial actions on the brain. They enter the brain and induce widespread stimulation of brain perfusion. They also provoke angiogenesis, neurogenesis and changes in neuron morphology, mainly in regions involved in learning and memory. Epicatechin improves various aspects of cognition in animals and humans. Chocolate also induces positive effects on mood and is often consumed under emotional stress. In addition, flavonoids preserve cognitive abilities during ageing in rats, lower the risk for developing Alzheimer's disease and decrease the risk of stroke in humans. In addition to their beneficial effects on the vascular system and on cerebral blood flow, flavonoids interact with signalization cascades involving protein and lipid kinases that lead to the inhibition of neuronal death by apoptosis induced by neurotoxicants such as oxygen radicals, and promote neuronal survival and synaptic plasticity. The present review intends to review the data available on the effects of cocoa and chocolate on brain health and cognitive abilities.

Marinobufagenin and cyclic strain may activate endothelial NADPH oxidase, contributing to the adverse impact of salty diets on vascular and cerebral health

Limited but provocative ecologic epidemiology suggests that dietary salt may play a central role in the genesis of not only of stroke, but also dementia, including Alzheimer's disease. Impairment of nitric oxide bioactivity in the cerebral microvasculature is a likely mediator of this effect. Salted diets evoke increased adrenal secretion of the natriuretic steroid marinobufagenin (MBG), which promotes natriuresis via inhibition of renal tubular Na+/K+-ATPase; this effect is notably robust in salt-sensitive rodent strains in which other compensatory natriuretic mechanisms are subnormally efficient. MBG-mediated inhibition of sodium pumps in vascular smooth muscle likely plays a role in the hypertension induced by salty diets in these rodents. However, salt sensitivity in humans is associated with increased vascular mortality and ventricular hypertrophy independent of blood pressure; this suggests that MBG may be pathogenic via mechanisms unrelated to blood pressure control. Indeed, recent evidence indicates that MBG, via interaction with alpha1 isoforms of the sodium pump, can activate various intracellular signaling pathways at physiological concentrations too low to notably inhibit pump activity. An overview of current evidence suggests the hypothesis that MBG - as well as the cyclic strain induced by hypertension per se - may induce endothelial oxidative stress by activating NADPH oxidase. If so, this could rationalize the increase in vascular and systemic oxidative stress observed in salt-sensitive rodents fed salty diets, or in rodents infused with MBG; moreover, if this effect is a particularly prominent determinant of oxidative stress in cerebrovascular endothelium, it might help to explain the virtual absence of stroke and dementia in low-salt societies. As a corollary of this hypothesis, it can be predicted that spirulina-derived phycobilins, which appear to mimic the physiological role of bilirubin as an inhibitor of NAPDH oxidase complexes, may have potential for ameliorating the adverse health impacts of MBG and of salty diets. Potassium-rich diets are also likely to be protective in this regard, as they should suppress MBG production via their natriuretic impact, while their stimulatory effect on sodium pump activity may exert a hyperpolarizing effect on plasma membranes that suppresses NADPH oxidase activity.

Angiogenesis-associated crosstalk between collagens, CXC chemokines, and thrombospondin domain-containing proteins

Excessive vascularization is a hallmark of many diseases including cancer, rheumatoid arthritis, diabetic nephropathy, pathologic obesity, age-related macular degeneration, and asthma. Compounds that inhibit angiogenesis represent potential therapeutics for many diseases. Karagiannis and Popel [Proc. Natl. Acad. Sci. USA 105(37):13775-13780, 2008] used a bioinformatics approach to identify more than 100 peptides with sequence homology to known angiogenesis inhibitors. The peptides could be grouped into families by the conserved domain of the proteins they were derived from. The families included type IV collagen fibrils, CXC chemokine ligands, and type I thrombospondin domain-containing proteins. The relationships between these families have received relatively little attention. To investigate these relationships, we approached the problem by placing the families of proteins in the context of the human interactome including >120,000 physical interactions among proteins, genes, and transcripts. We built on a graph theoretic approach to identify proteins that may represent conduits of crosstalk between protein families. We validated these findings by statistical analysis and analysis of a time series gene expression data set taken during angiogenesis. We identified six proteins at the center of the angiogenesis-associated network including three syndecans, MMP9, CD44, and versican. These findings shed light on the complex signaling networks that govern angiogenesis phenomena.

Alzheimer's proteins, oxidative stress, and mitochondrial dysfunction interplay in a neuronal model of Alzheimer's disease

In this paper, we discuss the interplay between beta-amyloid (Aβ) peptide, Tau fragments, oxidative stress, and mitochondria in the neuronal model of cerebellar granule neurons (CGNs) in which the molecular events reminiscent of AD are activated. The identification of the death route and the cause/effect relationships between the events leading to death could be helpful to manage the progression of apoptosis in neurodegeneration and to define antiapoptotic treatments acting on precocious steps of the death process. Mitochondrial dysfunction is among the earliest events linked to AD and might play a causative role in disease onset and progression. Recent studies on CGNs have shown that adenine nucleotide translocator (ANT) impairment, due to interaction with toxic N-ter Tau fragment, contributes in a significant manner to bioenergetic failure and mitochondrial dysfunction. These findings open a window for new therapeutic strategies aimed at preserving and/or improving mitochondrial function.

Potential complementarity of high-flavanol cocoa powder and spirulina for health protection

Recent studies show that ingestion of flavanol-rich cocoa powder provokes increased endothelial production of nitric oxide - an effect likely mediated by epicatchin - and thus may have considerable potential for promoting vascular health. The Kuna Indians of Panama, who regularly consume large amounts of flavanol-rich cocoa, are virtually free of hypertension and stroke, even though they salt their food. Of potentially complementary merit is the cyanobacterium spirulina, which has been used as a food in certain cultures. Spirulina is exceptionally rich in phycocyanobilin (PCB), which recently has been shown to act as a potent inhibitor of NADPH oxidase; this effect likely rationalizes the broad range of anti-inflammatory, cytoprotective, and anti-atherosclerotic effects which orally administered spirulina has achieved in rodent studies. In light of the central pathogenic role which NADPH oxidase-derived oxidant stress plays in a vast range of disorders, spirulina or PCB-enriched spirulina extracts may have remarkable potential for preserving and restoring health. Joint administration of flavanol-rich cocoa powder and spirulina may have particular merit, inasmuch as cocoa can mask the somewhat disagreeable flavor and odor of spirulina, whereas the antioxidant impact of spirulina could be expected to amplify the bioactivity of the nitric oxide evoked by cocoa flavanols in inflamed endothelium. Moreover, there is reason to suspect that, by optimizing cerebrovascular perfusion while quelling cerebral oxidant stress, cocoa powder and spirulina could collaborate in prevention of senile dementia. Thus, food products featuring ample amounts of both high-flavanol cocoa powder and spirulina may have considerable potential for health promotion, and merit evaluation in rodent studies and clinical trials.

Bioactivity studies and chemical profile of the antidiabetic plant Genista tenera

AIM OF THE STUDY

Genista tenera is a plant endemic to the island of Madeira and is used in folk medicine to control diabetes. In the present work we evaluate the antihyperglycaemic activity of its n-butanol extract and determine its chromatographic profile. In addition, this extract, the ethyl acetate and diethyl ether plant extracts were studied in order to assess the plant antioxidant and acetylcholinesterase inhibitory activities, as well as its cyto- and genotoxicities.

MATERIALS AND METHODS

HPLC-DAD-ESI-MS was used to analyze the flavonoid profile of the n-butanol extract. The antihyperglycaemic activity of this extract was performed over streptozotocin induced diabetic Wistar rats (200 mg/kg, bw/day), for 15 days. Antioxidant activity (DPPH assay) and acetylcholinesterase inhibitory effect (Ellman method) were also performed. Acute cytotoxicity and genotoxicity were assessed by proliferative index quantification and the short-term chromosomal aberration technique, after exposure of lymphocytes to the extracts.

RESULTS AND CONCLUSIONS

The n-butanol extract, where 21 monoglycosyl and 12 diglycosyl flavonoids were detected, significantly lowered blood glucose levels, bringing them to normal values after 15 days of treatment. The best radical scavenging activity was observed for the ethyl acetate extract (48.7% at 139.1 microg/mL), which was also the most effective one at the minimal concentration tested. The highest acetylcholinesterase inhibitory activity (77.0% at 70.0 microg/mL) was also obtained with the ethyl acetate extract. In vitro toxicity studies showed no evidence for acute cytotoxicity or genotoxicity. This is the first report on antidiabetic activity of genus Genista.

Neurosteroid hormone vitamin D and its utility in clinical nutrition

PURPOSE OF REVIEW

Vitamin D is a seco-steroid hormone with multiple functions in the nervous system. We discuss clinical and experimental evidence of the role of vitamin D in normal and pathological brain functions, and analyze the relative importance of vitamin D-modulated brain mechanisms at different stages of life. We also outline perspectives for the use of vitamin D in clinical nutrition to prevent or treat various brain disorders.

RECENT FINDINGS

Numerous brain dysfunctions are linked to vitamin D deficits and/or dysfunctions of its receptors. In both animals and humans, vitamin D serves as an important endogenous and/or exogenous regulator of neuroprotection, antiepileptic and anticalcification effects, neuro-immunomodulation, interplay with neurotransmitters and hormones, modulation of behaviors, brain ageing, and some other, less-explored, brain processes.

SUMMARY

Vitamin D emerges as an important neurosteroid hormone in the brain, with a strong potential for age-specific applications in clinical nutrition.