Vitamin E in neurodegenerative disorders: Alzheimer's disease

Associations between Brain Alpha-Tocopherol Stereoisomer Profile and Hallmarks of Brain Aging in Centenarians

Brain alpha-tocopherol (αT) concentration was previously reported to be inversely associated with neurofibrillary tangle (NFT) counts in specific brain structures from centenarians. However, the contribution of natural or synthetic αT stereoisomers to this relationship is unknown. In this study, αT stereoisomers were quantified in the temporal cortex (TC) of 47 centenarians in the Georgia Centenarian Study (age: 102.2 ± 2.5 years, BMI: 22.1 ± 3.9 kg/m2) and then correlated with amyloid plaques (diffuse and neuritic plaques; DPs, NPs) and NFTs in seven brain regions. The natural stereoisomer, RRR-αT, was the primary stereoisomer in all subjects, accounting for >50% of total αT in all but five subjects. %RRR was inversely correlated with DPs in the frontal cortex (FC) (ρ = -0.35, p = 0.032) and TC (ρ = -0.34, p = 0.038). %RSS (a synthetic αT stereoisomer) was positively correlated with DPs in the TC (ρ = 0.39, p = 0.017) and with NFTs in the FC (ρ = 0.37, p = 0.024), TC (ρ = 0.42, p = 0.009), and amygdala (ρ = 0.43, p = 0.008) after controlling for covariates. Neither RRR- nor RSS-αT were associated with premortem global cognition. Even with the narrow and normal range of BMIs, BMI was correlated with %RRR-αT (ρ = 0.34, p = 0.021) and %RSS-αT (ρ = -0.45, p = 0.002). These results providing the first characterization of TC αT stereoisomer profiles in centenarians suggest that DP and NFT counts, but not premortem global cognition, are influenced by the brain accumulation of specific αT stereoisomers. Further study is needed to confirm these findings and to determine the potential role of BMI in mediating this relationship.

Oxidative stress in the brain-lung crosstalk: cellular and molecular perspectives

Oxidative stress is caused by an imbalance between the production of reactive oxygen species (ROS) and the body's ability to counteract their harmful effects, playing a key role in the pathogenesis of brain and lung-related diseases. This review comprehensively examines the intricate mechanisms by which oxidative stress influences cellular and molecular pathways, contributing to neurodegenerative, cardiovascular, and respiratory disorders. Emphasizing the detrimental effects on both brain and lung health, we discuss innovative diagnostic biomarkers, such as 8-hydroxy-2'-deoxyguanosine (8-OHdG), and the potential of antioxidant therapies. For these topics, we provide insights into future research directions in the field of oxidative stress treatment, including the development of personalized treatment approaches, the discovery and validation of novel biomarkers, and the development of new drug delivery systems. This review not only provides a new perspective on understanding the role of oxidative stress in brain and lung-related diseases but also offers new insights for future clinical treatments.

Disorders of Endogenous and Exogenous Antioxidants in Neurological Diseases

In diseases of the central nervous system, such as Alzheimer's disease (AD), Parkinson's disease (PD), stroke, amyotrophic lateral sclerosis (ALS), Huntington's disease (HD), and even epilepsy and migraine, oxidative stress load commonly surpasses endogenous antioxidative capacity. While oxidative processes have been robustly implicated in the pathogenesis of these diseases, the significance of particular antioxidants, both endogenous and especially exogenous, in maintaining redox homeostasis requires further research. Among endogenous antioxidants, enzymes such as catalase, superoxide dismutase, and glutathione peroxidase are central to disabling free radicals, thereby preventing oxidative damage to cellular lipids, proteins, and nucleic acids. Whether supplementation with endogenously occurring antioxidant compounds such as melatonin and glutathione carries any benefit, however, remains equivocal. Similarly, while the health benefits of certain exogenous antioxidants, including ascorbic acid (vitamin C), carotenoids, polyphenols, sulforaphanes, and anthocyanins are commonly touted, their clinical efficacy and effectiveness in particular neurological disease contexts need to be more robustly defined. Here, we review the current literature on the cellular mechanisms mitigating oxidative stress and comment on the possible benefit of the most common exogenous antioxidants in diseases such as AD, PD, ALS, HD, stroke, epilepsy, and migraine. We selected common neurological diseases of a basically neurodegenerative nature.

Alzheimer's Disease and Green Tea: Epigallocatechin-3-Gallate as a Modulator of Inflammation and Oxidative Stress

Alzheimer's disease (AD) is the most common cause of dementia, characterised by a marked decline of both memory and cognition, along with pathophysiological hallmarks including amyloid beta peptide (Aβ) accumulation, tau protein hyperphosphorylation, neuronal loss and inflammation in the brain. Additionally, oxidative stress caused by an imbalance between free radicals and antioxidants is considered one of the main risk factors for AD, since it can result in protein, lipid and nucleic acid damage and exacerbate Aβ and tau pathology. To date, there is a lack of successful pharmacological approaches to cure or even ameliorate the terrible impact of this disease. Due to this, dietary compounds with antioxidative and anti-inflammatory properties acquire special relevance as potential therapeutic agents. In this context, green tea, and its main bioactive compound, epigallocatechin-3-gallate (EGCG), have been targeted as a plausible option for the modulation of AD. Specifically, EGCG acts as an antioxidant by regulating inflammatory processes involved in neurodegeneration such as ferroptosis and microglia-induced cytotoxicity and by inducing signalling pathways related to neuronal survival. Furthermore, it reduces tau hyperphosphorylation and aggregation and promotes the non-amyloidogenic route of APP processing, thus preventing the formation of Aβ and its subsequent accumulation. Taken together, these results suggest that EGCG may be a suitable candidate in the search for potential therapeutic compounds for neurodegenerative disorders involving inflammation and oxidative stress, including Alzheimer's disease.

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.

Evidence for Oxidative Pathways in the Pathogenesis of PD: Are Antioxidants Candidate Drugs to Ameliorate Disease Progression?

Parkinson’s disease (PD) is a progressive neurodegenerative disorder that arises due to a complex and variable interplay between elements including age, genetic, and environmental risk factors that manifest as the loss of dopaminergic neurons. Contemporary treatments for PD do not prevent or reverse the extent of neurodegeneration that is characteristic of this disorder and accordingly, there is a strong need to develop new approaches which address the underlying disease process and provide benefit to patients with this debilitating disorder. Mitochondrial dysfunction, oxidative damage, and inflammation have been implicated as pathophysiological mechanisms underlying the selective loss of dopaminergic neurons seen in PD. However, results of studies aiming to inhibit these pathways have shown variable success, and outcomes from large-scale clinical trials are not available or report varying success for the interventions studied. Overall, the available data suggest that further development and testing of novel therapies are required to identify new potential therapies for combating PD. Herein, this review reports on the most recent development of antioxidant and anti-inflammatory approaches that have shown positive benefit in cell and animal models of disease with a focus on supplementation with natural product therapies and selected synthetic drugs.

Hepatoprotective and neuroprotective effect of taxifolin on hepatic encephalopathy in rats

This study was planned to assess the potential protective effects of taxifolin against thioacetamide-induced hepatic encephalopathy and subsequently to portray its behavioural results. The experimental model was induced with three doses of (200 mg/kg i.p.) thioacetamide and taxifolin (50 and 100 mg/kg, p.o.) was administered for fourteen days. Taxifolin effectively attenuated hepatic encephalopathy through decrease in AST, ALT, ALP and LDH concentrations and improvement of hyperammonemia, and increase in antioxidant capacity by decreasing MDA, ROS, and increasing CAT and GSH. In addition, the expressions of NF-κB, TNF-α, IL-1β, caspase-3 and Bax was down-regulated while IL-10 and Bcl-2 expressions were up-regulated with taxifolin treatment. The recovery was confirmed by downregulation of iNOS and 8-OHdG expressions in our immunohistochemical analysis. Taxifolin treatment reduced the disrupting role of thioacetamide as seen by corrected hyperammonemia as well as preservation of astrocyte and hepatocyte structure. Elevated plus maze and locomotor activity tests also proved that taxifolin might repeal the neurobehavioral disabilities. In conclusion, taxifolin has shown hepatoprotective and neuroprotective roles with antioxidant and anti-inflammatory effects, as well as suppressing the excessive release of ammonia, and it eventually reversed neurobehavioral impairments.

Emerging role of HDL in brain cholesterol metabolism and neurodegenerative disorders

High-density lipoproteins (HDLs play a key role in cholesterol homeostasis maintenance in the central nervous system (CNS), by carrying newly synthesized cholesterol from astrocytes to neurons, to support their lipid-related physiological functions. As occurs for plasma HDLs, brain lipoproteins are assembled through the activity of membrane cholesterol transporters, undergo remodeling mediated by specific enzymes and transport proteins, and finally deliver cholesterol to neurons by a receptor-mediated internalization process. A growing number of evidences indicates a strong association between alterations of CNS cholesterol homeostasis and neurodegenerative disorders, in particular Alzheimer's disease (AD), and a possible role in this relationship may be played by defects in brain HDL metabolism. In the present review, we summarize and critically examine the current state of knowledge on major modifications of HDL and HDL-mediated brain cholesterol transport in AD, by taking into consideration the individual steps of this process. We also describe potential and encouraging HDL-based therapies that could represent new therapeutic strategies for AD treatment. Finally, we revise the main plasma and brain HDL modifications in other neurodegenerative disorders including Parkinson's disease (PD), Huntington's disease (HD), and frontotemporal dementia (FTD).

Oxidative Stress and Cognitive Decline: The Neuroprotective Role of Natural Antioxidants

Free- radicals (Oxygen and Nitrogen species) are formed in mitochondria during the oxidative phosphorylation. Their high reactivity, due to not-engaged electrons, leads to an increase of the oxidative stress. This condition affects above all the brain, that usually needs a large oxygen amount and in which there is the major possibility to accumulate "Reacting Species." Antioxidant molecules are fundamental in limiting free-radical damage, in particular in the central nervous system: the oxidative stress, in fact, seems to worsen the course of neurodegenerative diseases. The aim of this review is to sum up natural antioxidant molecules with the greatest neuroprotective properties against free radical genesis, understanding their relationship with the Central Nervous System.

Dual concentration-dependent effect of ascorbic acid on PAP(248-286) amyloid formation and SEVI-mediated HIV infection

Human semen contains various amyloidogenic peptides derived from Prostatic Acid Phosphatase (PAP) and Semenogelin proteins that are capable of enhancing HIV-1 infection when assembled into fibrils. The best characterized among them is a 39 amino acid peptide PAP(248–286), which forms amyloid fibrils termed SEVI (semen-derived enhancer of viral infection) that increase the infectivity of HIV-1 by orders of magnitude. Inhibiting amyloid formation by PAP(248–286) may mitigate the sexual transmission of HIV-1. Several vitamins have been shown to reduce the aggregation of amyloids such as Aβ, α-Synuclein, and Tau, which are associated with neurodegenerative diseases. Since ascorbic acid (AA, vitamin C) is the most abundant vitamin in semen with average concentrations of 0.4 mM, we here examined how AA affects PAP(248–286) aggregation in vitro. Using ThT binding assays, transmission electron microscopy, and circular dichroism spectroscopy, a dual and concentration-dependent behavior of AA in modulating PAP(248–286) fibril formation was observed. We found that low molar ratios of AA:PAP(248–286) promoted whereas high molar ratios inhibited PAP(248–286) fibril formation. Accordingly, PAP(248–286) aggregated in the presence of low amounts of AA enhanced HIV-1 infection, whereas excess amounts of AA during aggregation reduced the infectivity enhancing effect in cell culture. Collectively, this work provides a biophysical insight into the effect of AA, an important seminal component, on SEVI fibrillation which might impact amyloid formation kinetics, thereby modulating the biological activity of semen amyloids.

Human semen contains various amyloidogenic peptides derived from Prostatic Acid Phosphatase (PAP) and Semenogelin proteins that are capable of enhancing HIV-1 infection when assembled into fibrils.

The medicinal chemistry of mitochondrial dysfunction: a critical overview of efforts to modulate mitochondrial health

Mitochondria are subcellular organelles that perform a variety of critical biological functions, including ATP production and acting as hubs of immune and apoptotic signalling. Mitochondrial dysfunction has been extensively linked to the pathology of multiple neurodegenerative disorders, resulting in significant investment from the drug discovery community. Despite extensive efforts, there remains no disease modifying therapies for neurodegenerative disorders. This manuscript aims to review the compounds historically used to modulate the mitochondrial network through the lens of modern medicinal chemistry, and to offer a perspective on the evidence that relevant exposure was achieved in a representative model and that exposure was likely to result in target binding and engagement of pharmacology. We hope this manuscript will aid the community in identifying those targets and mechanisms which have been convincingly (in)validated with high quality chemical matter, and those for which an opportunity exists to explore in greater depth.

Mitochondrial Dysfunction as a Driver of Cognitive Impairment in Alzheimer's Disease

Alzheimer’s disease (AD) is the most frequent cause of age-related neurodegeneration and cognitive impairment, and there are currently no broadly effective therapies. The underlying pathogenesis is complex, but a growing body of evidence implicates mitochondrial dysfunction as a common pathomechanism involved in many of the hallmark features of the AD brain, such as formation of amyloid-beta (Aβ) aggregates (amyloid plaques), neurofibrillary tangles, cholinergic system dysfunction, impaired synaptic transmission and plasticity, oxidative stress, and neuroinflammation, that lead to neurodegeneration and cognitive dysfunction. Indeed, mitochondrial dysfunction concomitant with progressive accumulation of mitochondrial Aβ is an early event in AD pathogenesis. Healthy mitochondria are critical for providing sufficient energy to maintain endogenous neuroprotective and reparative mechanisms, while disturbances in mitochondrial function, motility, fission, and fusion lead to neuronal malfunction and degeneration associated with excess free radical production and reduced intracellular calcium buffering. In addition, mitochondrial dysfunction can contribute to amyloid-β precursor protein (APP) expression and misprocessing to produce pathogenic fragments (e.g., Aβ1-40). Given this background, we present an overview of the importance of mitochondria for maintenance of neuronal function and how mitochondrial dysfunction acts as a driver of cognitive impairment in AD. Additionally, we provide a brief summary of possible treatments targeting mitochondrial dysfunction as therapeutic approaches for AD.

Effects of vitamin E on neurodegenerative diseases: an update

Vitamin E deficiency is associated with many neurological problems. Although the mechanisms of vitamin E action in neurodegenerative diseases are not clear, there are many possible mechanisms. Examples of such mechanisms are the protective effects of vitamin E against oxidative stress damage and its suppressive role in the expression of many genes involved in the development of neurodegeneration. Many studies have evaluated the relationship between vitamin E intake or vitamin E levels in body fluids and neurodegenerative diseases. Some studies concluded that vitamin E can play a protective role in neurodegeneration with respect to diseases such as Alzheimer's disease (AD), Parkinson's disease (PD), stroke and amyotrophic lateral sclerosis (ALS). Vitamin E supplementation was also associated with risk factors for some neurodegenerative diseases. In this review, we discuss the possible effects of vitamin E on the development and course of AD, PD, stroke and ALS, and the potential mechanisms involved.

Vitamin E deficiency is associated with many neurological problems. Although the mechanisms of vitamin E action in neurodegenerative diseases are not clear, there are many possible mechanisms. Examples of such mechanisms are the protective effects of vitamin E against oxidative stress damage and its suppressive role in the expression of many genes involved in the development of neurodegeneration. Many studies have evaluated the relationship between vitamin E intake or vitamin E levels in body fluids and neurodegenerative diseases. Some studies concluded that vitamin E can play a protective role in neurodegeneration with respect to diseases such as Alzheimer’s disease (AD), Parkinson’s disease (PD), stroke and amyotrophic lateral sclerosis (ALS). Vitamin E supplementation was also associated with risk factors for some neurodegenerative diseases. In this review, we discuss the possible effects of vitamin E on the development and course of AD, PD, stroke and ALS, and the potential mechanisms involved.

Targeting Mitochondrial Dysfunction for Bipolar Disorder

People with bipolar disorder (BD) all too often have suboptimal long-term outcomes with existing treatment options. They experience relapsing episodes of depression and mania and also have interepisodic mood and anxiety symptoms. We need to have a better understanding of the pathophysiology of BD if we are to make progress in improving these outcomes. This chapter will focus on the critical role of mitochondria in human functioning, oxidative stress, and the biological mechanisms of mitochondria in BD. Additionally, this chapter will present the evidence that, at least for some people, BD is a product of mitochondrial dysregulation. We review the modulators of mitochondria, the connection between current BD medication treatments and mitochondria, and additional medications that have theoretical potential to treat BD.

Bacopa monnieri, a Neuroprotective Lead in Alzheimer Disease: A Review on Its Properties, Mechanisms of Action, and Preclinical and Clinical Studies

Alzheimer disease is a neurodegenerative disease that is signified by cognitive decline, memory loss, and erratic behavior. Till date, no cure for Alzheimer exists and the current Alzheimer medications have limited effectiveness. However, herbal medicines may slow down the disease’s progression, which may hopefully reduce the number of cases in the years to come. Numerous studies have been done on characterizing the neuroprotective properties from plants belonging to Scrophulariaceae family, particularly Bacopa monnieri and its polyphenolic compounds known as bacosides. This review presents the findings on bacosides in therapeutic plants and their impact on Alzheimer disease pathology. These reports present data on the clinical, cellular activities, phytochemistry, and biological applications that may be used in new drug treatment for Alzheimer disease.

Chemical Composition and Antioxidant Activity of Monguba (Pachira aquatica) Seeds

Monguba fruit has a seed with a chestnut-like flavor that can be consumed boiled, fried, and roasted. These nutritious seeds also have been used in popular medicine to treat several diseases. Nevertheless, the nutritional and functional potential of monguba seed is still underexploited. In this sense, we investigated the nutritional and functional components of monguba seeds. These seeds showed high total content of sugars, mainly sucrose, whereas the content of the raffinose family oligosaccharides was low. The mineral assay showed high amount of minerals, namely potassium, calcium, magnesium and zinc, which indicate that monguba seeds can be a new source of these minerals. UHPLC-ESI-MS/MS analysis showed caffeic, ferulic and 4-hydroxybenzoic acids as the main phenolic compounds, mainly in the esterified form, in these seeds. Monguba seed showed high lipid content, in which the main compounds were palmitic acid and γ-tocopherol. The soluble and insoluble phenolic fractions from monguba seeds showed high antioxidant activity measured by the oxygen radical absorption capacity (ORAC) and the trolox equivalent antioxidant capacity (TEAC) assays. Therefore, the monguba seeds have great potential to be explored by food, pharmaceutical and cosmetic industries due to their chemical composition.

Mitochondrial Agents for Bipolar Disorder

Background

Bipolar disorder is a chronic and often debilitating illness. Current treatment options (both pharmaco- and psychotherapy) have shown efficacy, but for many leave a shortfall in recovery. Advances in the understanding of the pathophysiology of bipolar disorder suggest that interventions that target mitochondrial dysfunction may provide a therapeutic benefit.

Methods

This review explores the current and growing theoretical rationale as well as existing preclinical and clinical data for those therapies aiming to target the mitochondrion in bipolar disorder. A Clinicaltrials.gov and ANZCTR search was conducted for complete and ongoing trials on mitochondrial agents used in psychiatric disorders. A PubMed search was also conducted for literature published between January 1981 and July 2017. Systematic reviews, randomized controlled trials, observational studies, case series, and animal studies with an emphasis on agents affecting mitochondrial function and its role in bipolar disorder were included. The search was augmented by manually searching the references of key papers and related literature. The results were presented as a narrative review.

Results

Mitochondrial agents offer new horizons in mood disorder treatment. While some negative effects have been reported, most compounds are overall well tolerated and have generally benign side-effect profiles.

Conclusions

The study of neuroinflammation, neurodegeneration, and mitochondrial function has contributed the understanding of bipolar disorder's pathophysiology. Agents targeting these pathways could be a potential therapeutic strategy. Future directions include identification of novel candidate mitochondrial modulators as well as rigorous and well-powered clinical trials.

Oxidative stress in cerebral small vessel disease. Role of reactive species

Cerebral small vessel disease (CSVD) is a wide term describing the condition affecting perforating arterial branches as well as arterioles, venules, and capillaries. Cerebral vascular net is one of the main targets of localised oxidative stress processes causing damage to vasculature, changes in the blood flow and blood-brain barrier and, in consequence, promoting neurodegenerative alterations in the brain tissue. Numerous studies report the fact of oxidation to proteins, sugars, lipids and nucleic acids, occurring in most neurodegenerative diseases mainly in the earliest stages and correlations with the development of cognitive and motor disturbances. The dysfunction of endothelium can be caused by oxidative stress and inflammatory mechanisms as a result of reactions and processes generating extensive reactive oxygen species (ROS) production such as high blood pressure, oxidised low density lipoproteins (oxLDL), very low density lipoproteins (vLDL), diabetes, homocysteinaemia, smoking, and infections. Several animal studies show positive aspects of ROS, especially within cerebral vasculature.

Association of serum carotenoid, retinol, and tocopherol concentrations with the progression of Parkinson's Disease

BACKGROUND/OBJECTIVES

A pivotal role of oxidative stress has been emphasized in the pathogenesis as well as in the disease progression of Parkinson's disease (PD). We aimed at investigating serum levels of antioxidant vitamins and elucidating whether they could be associated with the pathogenesis and progression of PD.

MATERIALS/METHODS

Serum levels of retinol, α- and γ-tocopherols, α- and β-carotenes, lutein, lycopene, zeaxanthin and β-cryptoxanthin were measured and compared between 104 patients with idiopathic PD and 52 healthy controls matched for age and gender. In order to examine the relationship between antioxidant vitamins and the disease progression, multiple group comparisons were performed among the early PD (Hoehn and Yahr stage I and II, N = 47), advanced PD (stage III and IV, N = 57) and control groups. Separate correlation analyses were performed between the measured antioxidant vitamins and clinical variables, such as Hoehn and Yahr stage and Unified Parkinson's Disease Rating Scale (UPDRS) motor score.

RESULTS

Compared to controls, PD patients had lower levels of α- and β-carotenes and lycopene. α-carotene, β-carotene and lycopene levels were significantly reduced in advanced PD patients relative to early PD patients and were negatively correlated with Hoehn and Yahr stage and UPDRS motor score in PD patients. No significant differences were found in serum levels of retinol, α- and γ-tocopherols, and other carotenoids between PD patients and controls. No significant correlations were found between these vitamin levels and clinical variables in PD patients.

CONCLUSIONS

We found that serum levels of some carotenoids, α-carotene, β-carotene and lycopene, were lower in PD patients, and that these carotenoids inversely correlated with clinical variables representing disease progression. Our findings suggest that decreases in serum α-carotene, β-carotene and lycopene may be associated with the pathogenesis as well as progression of PD.

Subgenome-specific assembly of vitamin E biosynthesis genes and expression patterns during seed development provide insight into the evolution of oat genome

Vitamin E is essential for humans and thus must be a component of a healthy diet. Among the cereal grains, hexaploid oats (Avena sativa L.) have high vitamin E content. To date, no gene sequences in the vitamin E biosynthesis pathway have been reported for oats. Using deep sequencing and orthology-guided assembly, coding sequences of genes for each step in vitamin E synthesis in oats were reconstructed, including resolution of the sequences of homeologs. Three homeologs, presumably representing each of the three oat subgenomes, were identified for the main steps of the pathway. Partial sequences, likely representing pseudogenes, were recovered in some instances as well. Pairwise comparisons among homeologs revealed that two of the three putative subgenome-specific homeologs are almost identical for each gene. Synonymous substitution rates indicate the time of divergence of the two more similar subgenomes from the distinct one at 7.9-8.7 MYA, and a divergence between the similar subgenomes from a common ancestor 1.1 MYA. A new proposed evolutionary model for hexaploid oat formation is discussed. Homeolog-specific gene expression was quantified during oat seed development and compared with vitamin E accumulation. Homeolog expression largely appears to be similar for most of genes; however, for some genes, homoeolog-specific transcriptional bias was observed. The expression of HPPD, as well as certain homoeologs of VTE2 and VTE4, is highly correlated with seed vitamin E accumulation. Our findings expand our understanding of oat genome evolution and will assist efforts to modify vitamin E content and composition in oats.

Modulation of Brain Glutathione Reductase and Peroxiredoxin 2 by α-Tocopheryl Phosphate

α-Tocopheryl phosphate (αTP) is a phosphorylated form of α-tocopherol. Since it is phosphorylated in the hydroxyl group that is essential for the antioxidant property of α-tocopherol, we hypothesized that αTP would modulate the antioxidant system, rather than being an antioxidant agent per se. α-TP demonstrated antioxidant activity in vitro against iron-induced oxidative stress in a mitochondria-enriched fraction preparation treated with 30 or 100 µM α-TP. However, this effect was not observed ex vivo with mitochondrial-enriched fraction from mice treated with an intracerebroventricular injection of 0.1 or 1 nmol/site of αTP. Two days after treatment (1 nmol/site αTP), peroxiredoxin 2 (Prx2) and glutathione reductase (GR) expression and GR activity were decreased in cerebral cortex and hippocampus. Glutathione content, glutathione peroxidase, and thioredoxin reductase activities were not affected by αTP. In conclusion, the persistent decrease in GR and Prx2 protein content is the first report of an in vivo effect of αTP on protein expression in the mouse brain, potentially associated to a novel and biologically relevant function of this naturally occurring compound.

Hot melt extrusion as an approach to improve solubility, permeability and oral absorption of a psychoactive natural product, piperine

OBJECTIVE

The aims of the current research project were to investigate the efficiency of various polymers to enhance the solubility and increase the systemic absorption of piperine using hot melt extrusion technology.

METHODS

Piperine 10-40% w/w and Eudragit(®) EPO/Kollidon(®) VA 64 or Soluplus(®) were mixed, and the resulting blends were extruded using a twin-screw extruder (Process 11, Thermo Fisher Scientific). Drug release profiles and piperine solubility studies of the extrudates were evaluated. A non-everted intestinal sac was employed for the most promising formulation, 10% w/w piperine/Soluplus(®) , and pure piperine to study the permeability characteristics.

KEY FINDINGS

Dissolution studies demonstrated enhancement in piperine per cent release of 10% and 20% w/w piperine/Soluplus(®) extrudates up to 95% and 74%, respectively. The solubility of 10% and 20% piperine/Soluplus(®) increased more than 160- and 45-fold in water, respectively. Furthermore, permeability studies demonstrated the enhancement in piperine absorption of 10% w/w piperine/Soluplus(®) extrudates up to 158.9 μg/5 ml compared with pure piperine at 1.3 μg/5 ml within 20 min.

CONCLUSION

These results demonstrated that increasing the bioavailability of piperine may be achieved as demonstrated by findings in this study.

Intranasal Piperine-Loaded Chitosan Nanoparticles as Brain-Targeted Therapy in Alzheimer's Disease: Optimization, Biological Efficacy, and Potential Toxicity

Piperine (PIP) is a phytopharmaceutical with reported neuroprotective potential in Alzheimer's disease (AD). Oral PIP delivery suffers from its hydrophobicity and pre-systemic metabolism. In this article, mono-disperse intranasal chitosan nanoparticles (CS-NPs) were elaborated for brain targeting of PIP. Formula optimization was based on particle size (PS), zeta potential (ZP), polydispersity index (PDI), % entrapment efficiency (% EE), release studies, and transmission electron microscopy. AD was induced in 48 male Wistar rats on which full behavioral and biochemical testing was conducted. Brain toxicity was assessed based on Caspase-3 assay for apoptosis and tumor necrosis factor for inflammation. Spherical NPs with optimum % EE (81.70), PS (248.50nm), PDI (0.24), and ZP (+56.30mV) were elaborated. PIP-NPs could significantly improve cognitive functions as efficient as standard drug (donpezil injection) with additional advantages of dual mechanism (Ach esterase inhibition and antioxidant effect). CS-NPs could significantly alleviate PIP nasal irritation and showed no brain toxicity. This work was the first to report additional mechanism of PIP in AD via anti-apoptosis and anti-inflammatory effects. To conclude, mucoadhesive CS-NPs were successfully tailored for effective, safe, and non-invasive PIP delivery with 20-folds decrease in oral dose, opening a gate for a future with lower AD morbidity. © 2015 Wiley Periodicals, Inc. and the American Pharmacists Association J Pharm Sci 104:3544-3556, 2015.

Bioactive Properties of Tabebuia impetiginosa-Based Phytopreparations and Phytoformulations: A Comparison between Extracts and Dietary Supplements

Tabebuia impetiginosa (Mart. ex DC.) Standl. has been used in traditional medicine for many centuries, being nowadays marketed as dried plant material (inner bark) for infusions, pills, and syrups. The main objective of the present work was to validate its popular use through the bioactivity evaluation of the inner bark (methanolic extract and infusion) and of two different formulations (pills and syrup) also based on the same plant-material. The antioxidant activity was evaluated by in vitro assays testing free radical scavenging activity, reducing power and inhibition of lipid peroxidation in brain homogenates. The cytotoxicity was determined in four human tumor cell lines (MCF-7, NCI-H460, HeLa and HepG2, and also in non-tumor cells (porcine liver primary cells, PLP2)). Furthermore, the sample was chemically characterized regarding free sugars, organic acids, fatty acids, and tocopherols. Syrup and methanolic extract showed the highest antioxidant activity, related to their highest amount of phenolics and flavonoids. Methanolic extract was the only sample showing cytotoxic effects on the tested human tumor cell lines, but none of the samples showed toxicity in PLP2. Glucose and oxalic acid were, respectively, the most abundant sugar and organic acid in the sample. Unsaturated predominated over the saturated fatty acids, due to oleic, linoleic, and linolenic acids expression. α- and γ-Tocopherols were also identified and quantified. Overall, T. impetiginosa might be used in different phytoformulations, taking advantage of its interesting bioactive properties and chemical composition.

Vitamin E: Curse or Benefit in Alzheimer's Disease? A Systematic Investigation of the Impact of α-, γ- and δ-Tocopherol on Aß Generation and Degradation in Neuroblastoma Cells

OBJECTIVES

The E vitamins are a class of lipophilic compounds including tocopherols, which have high antioxidative properties. Because of the elevated lipid peroxidation and increased reactive oxidative species in Alzheimer's disease (AD) many attempts have been made to slow down the progression of AD by utilizing the antioxidative action of vitamin E. Beside the mixed results of these studies nothing is known about the impact of vitamin E on the mechanisms leading to amyloid-β production and degradation being responsible for the plaque formation, one of the characteristic pathological hallmarks in AD. Here we systematically investigate the influence of different tocopherols on Aβ production and degradation in neuronal cell lines.

MEASUREMENTS

Beside amyloid-β level the mechanisms leading to Aβ production and degradation are examined.

RESULTS

Surprisingly, all tocopherols have shown to increase Aβ level by enhancing the Aβ production and decreasing the Aβ degradation. Aβ production is enhanced by an elevated activity of the involved enzymes, the β- and γ-secretase. These secretases are not directly affected, but tocopherols increase their protein level and expression. We could identify significant differences between the single tocopherols; whereas α-tocopherol had only minor effects on Aβ production, δ-tocopherol showed the highest potency to increase Aβ generation. Beside Aβ production, Aβ clearance was decreased by affecting IDE, one of the major Aβ degrading enzymes.

CONCLUSIONS

Our results suggest that beside the beneficial antioxidative effects of vitamin E, tocopherol has in respect to AD also a potency to increase the amyloid-β level, which differ for the analysed tocopherols. We therefore recommend that further studies are needed to clarify the potential role of these various vitamin E species in respect to AD and to identify the form which comprises an antioxidative property without having an amyloidogenic potential.

Protective effect of sulfurous water in peripheral blood mononuclear cells of Alzheimer's disease patients

AIMS

One of the main features of sulfurous water (SW) is the presence of hydrogen sulfide (H2S), which confers its antioxidant activity. Since oxidative stress plays an important role in Alzheimer's disease (AD) we hypothesize that SW could have a protective effect in these patients.

MATERIAL AND METHODS

A therapeutic in vitro approach of SW was performed in peripheral blood mononuclear cells (PBMCs) of AD patients and in age-matched healthy non-demented controls using one modification of the comet assay (to measure oxidative DNA damage) and the MTT assay (as an indicator of cell viability). Hydrogen peroxide and homocysteine were used to induce oxidative DNA damage, and vitamin C, Trolox and N-acetyl-cysteine were selected as antioxidants of reference to compare SW treatment results.

KEY FINDINGS

SW did not increase per se the oxidative DNA damage of PBMC. Furthermore, SW protected them against enhanced oxidative stress in AD and control populations after pro-oxidant stimuli, with similar results to those observed when using the antioxidants of reference. Nevertheless, SW was the only treatment that could avoid the loss of viability of PBMC for all pro-oxidant stimuli in both populations, suggesting that H2S could confer to SW a more antioxidant capacity than other known antioxidants.

SIGNIFICANCE

The protective effect of SW was proved for the first time not only in DNA stability but also in cell viability preservation in AD, indicating that further research in other in vitro and in vivo models could lead to include SW as a possible therapy for AD.

Liver X receptor up-regulates α-tocopherol transfer protein expression and α-tocopherol status

Fat-soluble vitamin E (α-tocopherol) has antioxidant activity. α-Tocopherol transfer protein (α-TTP), a hepatic cytosolic protein, selectively binds α-tocopherol and has an important role regulating circulatory α-tocopherol levels. However, only a few studies have shown the transcriptional regulation of the α-TTP gene. Here, we demonstrate that liver X receptor (LXR) regulates α-TTP expression through direct interaction with the α-TTP gene promoter, and it modulates circulating α-tocopherol levels. LXR belongs to the nuclear receptor superfamily, acts as a ligand-dependent transcription factor for oxysterols and plays an important role in cholesterol metabolism and lipogenesis. We identified an LXR response element (LXRE; DR4, a direct repeat with four-nucleotides spacing) of the human α-TTP gene promoter by using luciferase and electrophoretic mobility shift assays. Mutations in this element abolished activation of this promoter. Moreover, treatment of vitamin E-deficient rats with T0901317, a synthetic LXR ligand, increased α-TTP expression in the liver and cerebrum and increased the plasma α-tocopherol levels. These results indicate that the LXR signaling pathway modulates α-TTP gene expression and plasma α-tocopherol levels. Our observations imply that the LXR signaling pathway might be a useful target for antioxidant properties by controlling the vitamin E status.

A key role for an impaired detoxification mechanism in the etiology and severity of autism spectrum disorders

BACKGROUND

Autism Spectrum Disorders (ASD) is a syndrome with a number of etiologies and different mechanisms that lead to abnormal development. The identification of autism biomarkers in patients with different degrees of clinical presentation (i.e., mild, moderate and severe) will give greater insight into the pathogenesis of this disease and will enable effective early diagnostic strategies and treatments for this disorder.

METHODS

In this study, the concentration of two toxic heavy metals, lead (Pb) and mercury (Hg), were measured in red blood cells, while glutathione-s-transferase (GST) and vitamin E, as enzymatic and non-enzymatic antioxidants, respectively, were measured in the plasma of subgroups of autistic patients with different Social Responsiveness Scale (SRS) and Childhood Autism Rating Scale (CARS) scores. The results were compared to age- and gender-matched healthy controls.

RESULTS

The obtained data showed that the patients with autism spectrum disorder had significantly higher Pb and Hg levels and lower GST activity and vitamin E concentrations compared with the controls. The levels of heavy metals (Hg and Pb), GST and vitamin E were correlated with the severity of the social and cognitive impairment measures (SRS and CARS). Receiver Operating Characteristics (ROC) analysis and predictiveness curves indicated that the four parameters show satisfactory sensitivity, very high specificity and excellent predictiveness. Multiple regression analyses confirmed that higher levels of Hg and Pb, together with lower levels of GST and vitamin E, can be used to predict social and cognitive impairment in patients with autism spectrum disorders.

CONCLUSION

This study confirms earlier studies that implicate toxic metal accumulation as a consequence of impaired detoxification in autism and provides insight into the etiological mechanism of autism.

Oxidative stress in Alzheimer's disease

Oxidative stress plays a significant role in the pathogenesis of Alzheimer's disease (AD), a devastating disease of the elderly. The brain is more vulnerable than other organs to oxidative stress, and most of the components of neurons (lipids, proteins, and nucleic acids) can be oxidized in AD due to mitochondrial dysfunction, increased metal levels, inflammation, and β-amyloid (Aβ) peptides. Oxidative stress participates in the development of AD by promoting Aβ deposition, tau hyperphosphorylation, and the subsequent loss of synapses and neurons. The relationship between oxidative stress and AD suggests that oxidative stress is an essential part of the pathological process, and antioxidants may be useful for AD treatment.

The synthesis and evaluation of novel hydroxyl substituted chalcone analogs with in vitro anti-free radicals pharmacological activity and in vivo anti-oxidation activity in a free radical-injury Alzheimer's model

Alzheimer's disease (AD) pathogenesis involves an imbalance between free radical formation and destruction. In order to obtain a novel preclinical anti-AD drug candidate, we synthesized a series of novel hydroxyl chalcone analogs which possessed anti-free radical activity, and screened their effects on scavenging 2,2-diphenyl-1-picrylhydrazyl (DPPH) and OH free radicals in vitro. Compound C7, 4,2'-dihydroxy-3,5-dimethoxychalcone was found to have potent activity in these anti-free radical activity tests. Further research revealed that C7 could elevate glutathione peroxidase (GSH-PX) and super oxide dismutase (SOD) levels and lower malonaldehyde (MDA) level in vivo in the Alzheimer's model. The indication of C7's effect on AD needs further study.

Attenuation of oxidative stress, neuroinflammation, and apoptosis by curcumin prevents cognitive deficits in rats postnatally exposed to ethanol

RATIONALE

Clinical and experimental evidence have demonstrated that alcohol consumption during pregnancy can disrupt brain development, leading to a variety of behavioral alterations including hyperactivity, motor dysfunction, and cognitive deficits in offsprings. Alcohol-induced neurocognitive deficits are associated with activation of oxidative-inflammatory cascade coupled with extensive apoptotic neurodegeneration in different brain regions.

OBJECTIVES

The present study was designed with an aim to investigate the protective effect of curcumin, a principal curcuminoid present in the Indian spice turmeric, against alcohol-induced cognitive deficits, neuroinflammation, and neuronal apoptosis in rat pups postnatally exposed to ethanol.

METHODS AND RESULTS

Male Wistar rat pups were administered ethanol (5 g/kg, 12 % v/v) by intragastric intubation on postnatal days (PD) 7, 8, and 9 and were treated with curcumin (30 and 60 mg/kg) from PD 6 to 28. Performance of ethanol-exposed pups that did not receive curcumin was significantly impaired as evaluated in both Morris water maze and elevated plus maze tasks recorded by using computer tracking. Cognitive deficit was associated with enhanced acetylcholinesterase activity, increased neuroinflammation (oxidative-nitrosative stress, TNF-α, IL-1β, and TGF-β1), and neuronal apoptosis (NF-κβ and caspase 3) in both cerebral cortex and hippocampus of ethanol-exposed pups. Chronic treatment with curcumin significantly ameliorated all the behavioral, biochemical, and molecular alterations in different brain regions of ethanol-exposed pups.

CONCLUSIONS

The current study demonstrates the possible involvement of oxidative-inflammatory cascade-mediated apoptotic signaling in cognitive deficits associated with postnatal ethanol exposure and points towards the neuroprotective potential of curcumin in mitigating alcohol-induced behavioral, biochemical, and molecular deficits.

Effect of one-year vitamin C- and E-supplementation on cerebrospinal fluid oxidation parameters and clinical course in Alzheimer's disease

Antioxidant vitamins are being widely discussed as a therapeutic option in Alzheimer's disease (AD). We recently found that supplementation with vitamin C and E over 1 month leads to an increase of their levels in cerebrospinal fluid (CSF) and a reduction of CSF lipid peroxidation. In the present study, we followed-up the biochemical and clinical effect of vitamin C and E supplementation in an open clinical trial over 1 year. Twelve AD patients stably taking a cholinesterase inhibitor were supplemented with vitamin C (1,000 mg/day) and E (400 I.U./day), while 11 patients taking cholinergic medication only served as a control group. Cognition was assessed at baseline, after 6 months and 12 months using the Mini-Mental State Examination; a more detailed testing of cognitive function was performed at baseline and after 12 months. From eight of the vitamin-supplemented patients, CSF was taken at baseline, after 1 month and after 1 year to measure the antioxidant effect of vitamin supplementation on CSF lipids using a recently established in vitro oxidation assay. CSF antioxidant vitamins were significantly increased after 1 month and 1 year of supplementation, while in vitro oxidation of CSF lipids was significantly reduced only after 1 year of the supplementation. The clinical course of AD did not significantly differ between the vitamin and the control group. We conclude that supplementation with vitamins E and C did not have a significant effect on the course of AD over 1 year despite of a limited antioxidant effect that could be observed in CSF.

Antioxidant therapies for Alzheimer's disease

Alzheimer's disease (AD) is the most common neurodegenerative disease featuring progressive impairments in memory, cognition, and behavior and ultimately leads to death. The histopathological changes of Alzheimer's disease include neuronal and synaptic loss, formation of extracellular senile plaques and intracellular neurofibrillary tangles in brain. Multiple lines of evidence indicate that oxidative stress not only strongly participates in an early stage of Alzheimer's disease prior to cytopathology, but plays an important role in inducing and activating multiple cell signaling pathways that contribute to the lesion formations of toxic substances and then promotes the development of Alzheimer's disease. Many years of studies show that antioxidant therapies have enjoyed general success in preclinical studies. Therefore, this paper mainly focuses on the recent developments of common used antioxidant therapies for Alzheimer's disease and thus provides indications for future potential antioxidant therapeutic strategies of neurodegenerative diseases.

Protective Action of Neurotrophic Factors and Estrogen against Oxidative Stress-Mediated Neurodegeneration

Oxidative stress is involved in the pathogenesis of neurodegenerative disorders such as Alzheimer's disease, Parkinson's disease, and Huntington's disease. Low levels of reactive oxygen species (ROS) and reactive nitrogen species (RNS) are important for maintenance of neuronal function, though elevated levels lead to neuronal cell death. A complex series of events including excitotoxicity, Ca(2+) overload, and mitochondrial dysfunction contributes to oxidative stress-mediated neurodegeneration. As expected, many antioxidants like phytochemicals and vitamins are known to reduce oxidative toxicity. Additionally, growing evidence indicates that neurotrophic factors such as brain-derived neurotrophic factor (BDNF) and estrogens significantly prevent neuronal damage caused by oxidative stress. Here, we review and discuss recent studies addressing the protective mechanisms of neurotrophic factors and estrogen within this system.

Purple rice berry is neuroprotective and enhances cognition in a rat model of Alzheimer's disease

Alzheimer's disease, a neurodegenerative disease characterized by progressive memory loss and cognitive impairment, is the most common type of dementia in aging populations due to severe loss of cholinergic neurons in a specific area. Oxidative stress is known to be involved in the pathogenesis of this condition. Therefore, the cognition-enhancing and neuroprotective effects of rice berry (Oryza sativa), a purple-pigmented rice that is rich in antioxidant substances, was evaluated. Young adult male Wistar rats, weighing 180-220 g, were orally given rice berry once daily at doses of 180, 360, and 720 mg/kg of body weight for a period of 2 weeks before and 1 week after the induction of memory deficit and cholinergic lesions with AF64A, a specific cholinotoxin, via bilateral intracerebroventricular administration. One week following AF64A administration the rats were evaluated for spatial memory, neuron density, acetylcholinesterase activity, and hippocampal lipid peroxidation products. Our results showed that rice berry could significantly prevent memory impairment and hippocampal neurodegeneration in hippocampus. Moreover, it also decreased hippocampal acetylcholinesterase activity and lipid peroxidation product formation. These results suggest that rice berry has potential as an effective agent for neurodegeneration and memory impairment in Alzheimer's disease.

Ablation of the locus coeruleus increases oxidative stress in tg-2576 transgenic but not wild-type mice

Mice transgenic for production of excessive or mutant forms of beta-amyloid differ from patients with Alzheimer's disease in the degree of inflammation, oxidative damage, and alteration of intermediary metabolism, as well as the paucity or absence of neuronal atrophy and cognitive impairment. Previous observers have suggested that differences in inflammatory response reflect a discrepancy in the state of the locus coeruleus (LC), loss of which is an early change in Alzheimer's disease but which is preserved in the transgenic mice. In this paper, we extend these observations by examining the effects of the LC on markers of oxidative stress and intermediary metabolism. We compare four groups: wild-type or Tg2576 Aβ transgenic mice injected with DSP4 or vehicle. Of greatest interest were metabolites different between ablated and intact transgenics, but not between ablated and intact wild-type animals. The Tg2576_DSP4 mice were distinguished from the other three groups by oxidative stress and altered energy metabolism. These observations provide further support for the hypothesis that Tg2576 Aβ transgenic mice with this ablation may be a more congruent model of Alzheimer's disease than are transgenics with an intact LC.

Neuronutrition and Alzheimer's disease

Alzheimer's disease (AD) is a complex neurological disorder resulting from both genetic and environmental factors with the latter being particularly important for the sporadic form of the disease. As such, diets rich in saturated fatty acids and alcohol, and deficient in antioxidants and vitamins appear to promote the onset of the disease, while diets rich in unsaturated fatty acids, vitamins, antioxidants, and wine likely suppress its onset. In addition, evidence suggests that diets rich in polyphenols and some spices suppress the onset of AD by scavenging free radicals and preventing oxidative damage. Metal ions are known to catalyze the production of free radicals and induce mental retardation or dementia, and several studies have also identified metals such as Pb, Fe, Al, Cu, and Zn in AD pathogenesis. While specific metal chelators have been tested for therapy, they have not been very successful, probably due to their late administration, i.e., after brain damage has been triggered. Since several dietary polyphenols are known to chelate metals, their routine use may also be protective against the onset of AD. In this review, we summarize beneficial dietary techniques in the fight against AD.

Cognitive enhancement and neuroprotective effects of Bacopa monnieri in Alzheimer's disease model

ETHNOPHARMACOLOGICAL RELEVANCE

Bacopa monnieri (L.) Wettst., a plant belonging to the family Scrophulariaceae, has been used in the traditional system of Ayurvedic medicine to improve intelligence and memory for a long time. Therefore, the potential of this plant to protect against Alzheimer's disease has been raised but less supported document is available.

AIM OF THE STUDY

To determine the effect of alcoholic extract of Bacopa monnieri on cognitive function and neurodegeneration in animal model of Alzheimer's disease induced by ethylcholine aziridinium ion (AF64A).

MATERIALS AND METHODS

Male Wistar rats were orally given the alcoholic extract of Bacopa monnieri at doses of 20, 40 and 80 mg/kg BW via feeding needle for a period of 2 weeks before and 1 week after the intracerebroventricular administration of AF64A bilaterally. Rats were tested for spatial memory using Morris water maze test and the density of neurons and cholinergic neurons was determined using histological techniques 7 days after AF64A administration.

RESULTS

Bacopa monnieri extract improved the escape latency time (p<.01) in Morris water maze test. Moreover, the reduction of neurons and cholinergic neuron densities were also mitigated.

CONCLUSION

These findings suggest that Bacopa monnieri is a potential cognitive enhancer and neuroprotectant against Alzheimer's disease.

Present trends in vitamin E research

Nearly after one century of research and thousands of publications, the physiological function(s) of vitamin E remain unclear. Available evidence suggests a role in cell homeostasis that occurs through the modulation of specific signaling pathways and genes involved in proliferative, metabolic, inflammatory, and antioxidant pathways. Vitamin E presence in the human body is under close metabolic control so that only alpha-tocopherol and, to a lower extent, gamma-tocopherol are retained and delivered to tissues. Other vitamin E forms that are not retained in the body in significant amounts, exhibit responses in vitro that are different form those of alpha-tocopherol and may include tumor cell specific toxicity and apoptosis. These responses provide a therapeutic potential for these minor forms, either as such or metabolically modified, to produce bioactive metabolites. These cellular effects go beyond the properties of lipophilic antioxidant attributed to alpha-tocopherol particularly investigated for its alleged protective role in atherosclerosis or other oxidative stress conditions. Understanding signaling and gene expression effects of vitamin E could help assign a physiological role to this vitamin, which will be discussed in this review. Besides vitamin E signaling, attention will be given to tocotrienols as one of the emerging topics in vitamin E research and a critical re-examination of the most recent clinical trials will be provided together with the potential use of vitamin E in disease prevention and therapy.

Piperine, the main alkaloid of Thai black pepper, protects against neurodegeneration and cognitive impairment in animal model of cognitive deficit like condition of Alzheimer's disease

Recently, numerous medicinal plants possessing profound central nervous system effects and antioxidant activity have received much attention as food supplement to improve cognitive function against cognitive deficit condition including in Alzheimer's disease condition. Based on this information, the effect of piperine, a main active alkaloid in fruit of Piper nigrum, on memory performance and neurodegeneration in animal model of Alzheimer's disease have been investigated. Adult male Wistar rats (180-220 g) were orally given piperine at various doses ranging from 5, 10 and 20mg/kg BW at a period of 2 weeks before and 1 week after the intracerebroventricular administration of ethylcholine aziridinium ion (AF64A) bilaterally. The results showed that piperine at all dosage range used in this study significantly improved memory impairment and neurodegeneration in hippocampus. The possible underlying mechanisms might be partly associated with the decrease lipid peroxidation and acetylcholinesterase enzyme. Moreover, piperine also demonstrated the neurotrophic effect in hippocampus. However, further researches about the precise underlying mechanism are still required.