Dietary polyphenols and neurogenesis: Molecular interactions and implication for brain ageing and cognition

Phloretin alleviates sleep deprivation-induced cognitive impairment by reducing inflammation through PPARγ/NF-κB signaling pathway

Sleep loss leads to significant pathophysiological consequences, including cognitive impairment. The neuroinflammation are pivotal factors in the pathogenesis of cognitive impairment induced by sleep loss. The phloretin (PHL), derived from peel of juicy fruits, has demonstrated potent anti-inflammatory properties. However, the precise influence of PHL on the cognitive impairment triggered by sleep loss and its underlying mechanism remain uncertain. In the present study, mice were subjected to sleep deprivation (SD) paradigm. Cognitive impairment induced by SD were significantly relieved by administration of PHL in a dose-dependent manner. Furthermore, PHL not only mitigated the synaptic losses but also enhanced dendritic spine density and neuronal activity within mice hippocampus following exposure to SD. Moreover, PHL treatment decreased the microglial numbers and altered microglial morphology in the hippocampus to restore the M1/M2 balances; these effects were accompanied by regulation of pro-/anti-inflammatory cytokine production and secretion in SD-exposed mice. Additionally, in vivo and in vitro studies showed PHL might attenuate the inflammation through the PPARγ/NF-κB pathway. Our findings suggest that PHL exerts inhibitory effects on microglia-mediated neuroinflammation, thereby providing protection against cognitive impairment induced by SD through a PPAR-γ dependent mechanism. The results indicate PHL is expected to provide a valuable candidate for new drug development for SD-induced cognitive impairment in the future.

The bioenergetics of traumatic brain injury and its long-term impact for brain plasticity and function

Mitochondria provide the energy to keep cells alive and functioning and they have the capacity to influence highly complex molecular events. Mitochondria are essential to maintain cellular energy homeostasis that determines the course of neurological disorders, including traumatic brain injury (TBI). Various aspects of mitochondria metabolism such as autophagy can have long-term consequences for brain function and plasticity. In turn, mitochondria bioenergetics can impinge on molecular events associated with epigenetic modifications of DNA, which can extend cellular memory for a long time. Mitochondrial dysfunction leads to pathological manifestations such as oxidative stress, inflammation, and calcium imbalance that threaten brain plasticity and function. Hence, targeting mitochondrial function may have great potential to lessen the outcomes of TBI.

Diet enriched with high-phenolic cocoa potentiates hippocampal brain-derived neurotrophic factor expression and neurogenesis in healthy adult micewith subtle effects on memory

Cocoa is widely known for its health benefits, but its neurocognitive impact remains underexplored. This preclinical study aimed to investigate the effects of cocoa and cocoa polyphenols on hippocampal neuroplasticity, cognitive function and emotional behavior. Seventy young-adult C57BL/6JRj male and female mice were fed either a standard diet (CTR) or a diet enriched with 10% high-phenolic content cocoa (HPC) or low-phenolic content cocoa (LPC) for at least four weeks. In a first experiment, behavioral tests assessing exploratory behavior, emotional responses and hippocampal-dependent memory were conducted four weeks into the diet, followed by animal sacrifice a week later. Adult hippocampal neurogenesis and brain-derived neurotrophic factor (BDNF) expression in the hippocampus and prefrontal cortex were evaluated using immunohistochemistry and western blot. In a different experiment, hippocampal synaptic response, long-term potentiation and presynaptic-dependent short-term plasticity were studied by electrophysiology. Cocoa-enriched diets had minimal effects on exploratory activity and anxiety-like behavior, except for reduced locomotion in the LPC group. Only the HPC diet enhanced object recognition memory, while place recognition memory and spatial navigation remained unaffected. The HPC diet also increased adult hippocampal neurogenesis, boosting the proliferation, survival and number of young adult-born neurons. However, both cocoa-enriched diets increased immobility in the forced swimming test and hippocampal BDNF expression. Hippocampal electrophysiology revealed no alterations in neuroplasticity among diets. The results were mostly unaffected by sex. Overall, the HPC diet demonstrated greater potential regarding cognitive and neuroplastic benefits, suggesting a key role of cocoa flavanols in dietary interventions aimed at enhancing brain health.

Relationship of Curcumin with Aging and Alzheimer and Parkinson Disease, the Most Prevalent Age-Related Neurodegenerative Diseases: A Narrative Review

The elderly population is increasing worldwide every day. Age is a significant factor in the progression of neurological diseases, which can also cause cognitive decline and memory disorders. Inflammation and oxidative stress are primary drivers of senescence and disorders, particularly those associated with aging and neurodegenerative diseases. Bioactive phytochemicals are considered a promising therapeutic strategy in combating aging and age-related pathological conditions. One of the phytochemicals with diverse biological properties encompassing antioxidant, anti-inflammatory, antibacterial, antiviral, anticancer, antifungal, antidepressant, anti-allergic, and anti-aging properties is curcumin. Curcumin, a polyphenolic structure with a distinct orange hue and unique chemical properties, is derived from the roots of Curcuma longa, a member of the Zingiberaceae family, commonly known as turmeric. It has been noted that the incidence of neurodegenerative diseases is low in societies that consume curcumin widely. Therefore, this review investigates the effect of curcumin on aging and Alzheimer and Parkinson disease, which are the most prevalent age-related neurodegenerative diseases.

Quercetin-3-O-β-d-glucuronide in the Nuciferine Leaf Polyphenol Extract Promotes Neurogenesis Involving the Upregulation of the Tropomyosin Receptor Kinase (Trk) Receptor and AKT/Phosphoinositide 3-Kinase Signaling Pathway

Neurogenesis is crucial during the human lifespan for the maintenance of synaptic plasticity and normal function. The impairment of hippocampal neurogenesis in adults may lead to neurodegenerative disease, such as Alzheimer's disease. Miquelianin (quercetin-3-O-β-d-glucuronide, Q3GA) is a constituent of the nuciferine leaf polyphenol extract (NLPE), and it has protective effects against neurodegeneration. In this study, we examined the effect of the NLPE on neurogenesis and the mechanisms underlying Q3GA on neurogenesis. We fed 24-week-old male C57BL/6 mice with 0.1 or 0.25% NLPE for 2 weeks. NLPE treatment increased small spindle-shaped stem cell numbers in the subgranular zone and the number of doublecortin (DCX)- and neuron-specific nuclear protein (NeuN)-expressing neurons. HT22, a hippocampal cell line, treated with Q3GA revealed significant neurite growth and upregulated TrkR and PI3K/Akt levels. The evidence from a model of retinoic acid-induced SH-SY5Y cell differentiation showed that Q3GA or NLPE increases neurite growth significantly. Taken together, the NLPE containing Q3GA to promote neurogenesis involving the upregulation of TrkR and the PI3K/Akt signaling pathway might be potentiated as an alternative strategy for the treatment of neurodegeneration.

Impact of Gut Microbiota in Brain Ageing: Polyphenols as Beneficial Modulators

Brain ageing is a complex physiological process that includes several mechanisms. It is characterized by neuronal/glial dysfunction, alterations in brain vasculature and barriers, and the decline in brain repair systems. These disorders are triggered by an increase in oxidative stress and a proinflammatory state, without adequate antioxidant and anti-inflammatory systems, as it occurs in young life stages. This state is known as inflammaging. Gut microbiota and the gut–brain axis (GBA) have been associated with brain function, in a bidirectional communication that can cause loss or gain of the brain’s functionality. There are also intrinsic and extrinsic factors with the ability to modulate this connection. Among the extrinsic factors, the components of diet, principally natural components such as polyphenols, are the most reported. The beneficial effects of polyphenols in brain ageing have been described, mainly due to their antioxidants and anti-inflammatory properties, including the modulation of gut microbiota and the GBA. The aim of this review was, by following the canonical methodology for a state-of-the-art review, to compose the existing evidenced picture of the impact of the gut microbiota on ageing and their modulation by polyphenols as beneficial molecules against brain ageing.

Dietary Flavonoids and Adult Neurogenesis: Potential Implications for Brain Aging

Adult neurogenesis deficiency has been proposed to be a common hallmark in different age-related neurodegenerative diseases. The administration of flavonoids is currently reported as a potentially beneficial strategy for preventing brain aging alterations, including adult neurogenesis decline. Flavonoids are a class of plant-derived dietary polyphenols that have drawn attention for their neuroprotective and pro-cognitive effects. Although they undergo extensive metabolism and localize in the brain at low concentrations, flavonoids are now believed to improve cerebral vasculature and interact with signal transduction cascades involved in the regulation of adult neurogenesis. Furthermore, many dietary flavonoids have been shown to reduce oxidative stress and neuroinflammation, improving the neuronal microenvironment where adult neurogenesis occurs. The overall goal of this review is to summarize the evidence supporting the role of flavonoids in modulating adult neurogenesis as well as to highlight how these dietary agents may be promising candidates in restoring healthy brain function during physiological and pathological aging.

Natural Phytochemicals for the Treatment of Major Depressive Disorder: A Mini-Review of Pre- and Clinical Studies

Major Depressive Disorder (MDD) is a common mental illness that causes significant disability and declining quality of life. An overlap of multiple factors can be involved in the pathophysiology of this mood disorder, including increased inflammation and oxidative stress, change in neurotransmitters, decreased brain-derived neurotrophic factor (BDNF), activation of the hypothalamicpituitary- adrenal (HPA) axis, and changes in the microbiota-gut-brain axis. Although the classic treatment for MDD is safe, it is far from ideal, with delay to start the best clinic, side effects, and a large number of non-responses or partial-responses. Therefore, other alternatives are being studied to improve depressive symptoms, and, among them, the role of phytochemicals in food stands out. This mini-review will discuss the main phytochemicals present in foods with clinical and preclinical studies showing benefits for MDD treatment. In addition, the main mechanisms of action that are being proposed for each of these compounds will be addressed.

Chrysin-phospholipid complex-based solid dispersion for improved anti-aging and neuroprotective effects in mice

The present study aimed to improve the neuroprotective effect of chrysin (CHR) by combining two formulation techniques, phospholipid (PL) complexation and solid dispersion (SD). CHR-phospholipid complex (CHR-PLC) was prepared through solvent evaporation. The molar ratio CHR/PL (1:3), which exhibited the highest complexation efficiency, was selected for the preparation of CHR-PLC loaded SD (CHR-PLC-SD) with 2-hydroxypropyl β cyclodextrin (2-HPβCD) and polyvinylpyrrolidone 8000. CHR-PLC/2-HPβCD (1:2, w/w) displayed the highest aqueous solubility of CHR (5.86 times more than that of plain CHR). CHR-SD was also prepared using 2-HPβCD for comparison. The in vitro dissolution of CHR-PLC-SD4 revealed an enhancement in the dissolution rate over CHR-PLC (1:3), CHR-SD, and plain CHR by six times. The optimum formulations and plain CHR were evaluated for their neuroprotective effect on brain aging induced by D-galactose in mice. The results demonstrated a behavioral activity elevation, an increase of AMPK, LKB1, and PGC1α brain contents as well as a reduction of AGEs, GFAP, NT-3, TNF-α, and NF-κβ brain contents when compared with those of the D-galactose control group. Thus, the developed formulations stimulated neurogenesis and mitochondrial biogenesis as well as suppressed neuroinflammation and neurodegeneration. The order of activity was as follows: CHR-PLC-SD4 > CHR-PLC (1:3) > CHR-SD > plain CHR.

Nutrition and adult neurogenesis in the hippocampus: Does what you eat help you remember?

Neurogenesis is a complex process by which neural progenitor cells (NPCs)/neural stem cells (NSCs) proliferate and differentiate into new neurons and other brain cells. In adulthood, the hippocampus is one of the areas with more neurogenesis activity, which is involved in the modulation of both emotional and cognitive hippocampal functions. This complex process is affected by many intrinsic and extrinsic factors, including nutrition. In this regard, preclinical studies performed in rats and mice demonstrate that high fats and/or sugars diets have a negative effect on adult hippocampal neurogenesis (AHN). In contrast, diets enriched with bioactive compounds, such as polyunsaturated fatty acids and polyphenols, as well as intermittent fasting or caloric restriction, can induce AHN. Interestingly, there is also growing evidence demonstrating that offspring AHN can be affected by maternal nutrition in the perinatal period. Therefore, nutritional interventions from early stages and throughout life are a promising perspective to alleviate neurodegenerative diseases by stimulating neurogenesis. The underlying mechanisms by which nutrients and dietary factors affect AHN are still being studied. Interestingly, recent evidence suggests that additional peripheral mediators may be involved. In this sense, the microbiota-gut-brain axis mediates bidirectional communication between the gut and the brain and could act as a link between nutritional factors and AHN. The aim of this mini-review is to summarize, the most recent findings related to the influence of nutrition and diet in the modulation of AHN. The importance of maternal nutrition in the AHN of the offspring and the role of the microbiota-gut-brain axis in the nutrition-neurogenesis relationship have also been included.

Potential implications of polyphenolic compounds in neurodegenerative diseases

Neurodegenerative diseases are common chronic diseases related to progressive damage to the nervous system. Current neurodegenerative diseases present difficulties and despite extensive research efforts to develop new disease-modifying therapies, there is still no effective treatment for halting the neurodegenerative process. Polyphenols are biologically active organic compounds abundantly found in various plants. It has been reported that plant-derived dietary polyphenols may improve some disease states and promote health. Emerging pieces of evidence indicate that polyphenols are associated with neurodegenerative diseases. This review aims to overview the potential neuroprotective roles of polyphenols in most common neurodegenerative disorders, including Alzheimer's disease, Parkinson's disease, epilepsy, and ischemic stroke.

Microbiota-Gut-Brain Axis Regulation of Adult Hippocampal Neurogenesis

The birth, maturation, and integration of new neurons in the adult hippocampus regulates specific learning and memory processes, responses to stress, and antidepressant treatment efficacy. This process of adult hippocampal neurogenesis is sensitive to environmental stimuli, including peripheral signals from certain cytokines, hormones, and metabolites, which can promote or hinder the production and survival of new hippocampal neurons. The trillions of microorganisms resident to the gastrointestinal tract, collectively known as the gut microbiota, also demonstrate the ability to modulate adult hippocampal neurogenesis. In doing so, the microbiota-gut-brain axis can influence brain functions regulated by adult hippocampal neurogenesis. Unlike the hippocampus, the gut microbiota is highly accessible to direct interventions, such as prebiotics, probiotics, and antibiotics, and can be manipulated by lifestyle choices including diet. Therefore, understanding the pathways by which the gut microbiota shapes hippocampal neurogenesis may reveal novel targets for non-invasive therapeutics to treat disorders in which alterations in hippocampal neurogenesis have been implicated. This review first outlines the factors which influence both the gut microbiome and adult hippocampal neurogenesis, with cognizance that these effects might happen either independently or due to microbiota-driven mechanisms. We then highlight approaches for investigating the regulation of adult hippocampal neurogenesis by the microbiota-gut-brain axis. Finally, we summarize the current evidence demonstrating the gut microbiota's ability to influence adult hippocampal neurogenesis, including mechanisms driven through immune pathways, microbial metabolites, endocrine signalling, and the nervous system, and postulate implications for these effects in disease onset and treatment.

Polyphenols as potential enhancers of stem cell therapy against neurodegeneration

The potential of polyphenols for treating chronic-degenerative diseases (particularly neurodegenerative diseases) is attractive. However, the selection of the best polyphenol for each treatment, the mechanisms by which they act, and their efficacy are frequently discussed. In this review, the basics and the advances in the field, as well as suggestions for using natural and synthetic polyphenols alone or in a combinatorial strategy with stem cell assays, are compiled and discussed. Thus, stem cells exhibit several responses when polyphenols are added to their environment, which could provide us with knowledge for advancing the elucidation of the origin of neurodegeneration. But also, polyphenols are being included in the innovative strategies of novel therapies for treating neurodegenerative diseases as well as metabolic diseases related to neurodegeneration. In this regard, flavonoid compounds are suggested as the best natural polyphenols due to their several mechanisms for acting in ameliorative effects; but increasing reports are involving other polyphenols. Even if some facts limiting bioactivity prevent them from conventional use, some natural polyphenols and derivatives hold the promise for being improved compounds, judged by their induced effects. The current results suggest polyphenols as enhancers of stem cell therapy against the targeted diseases.

Role of Diet in Stem and Cancer Stem Cells

Diet and lifestyle factors greatly affect health and susceptibility to diseases, including cancer. Stem cells’ functions, including their ability to divide asymmetrically, set the rules for tissue homeostasis, contribute to health maintenance, and represent the entry point of cancer occurrence. Stem cell properties result from the complex integration of intrinsic, extrinsic, and systemic factors. In this context, diet-induced metabolic changes can have a profound impact on stem cell fate determination, lineage specification and differentiation. The purpose of this review is to provide a comprehensive description of the multiple “non-metabolic” effects of diet on stem cell functions, including little-known effects such as those on liquid-liquid phase separation and on non-random chromosome segregation (asymmetric division). A deep understanding of the specific dietetic requirements of normal and cancer stem cells may pave the way for the development of nutrition-based targeted therapeutic approaches to improve regenerative and anticancer therapies.

Therapeutic role of curcumin in adult neurogenesis for management of psychiatric and neurological disorders: a scientometric study to an in-depth review

Aberrant neurogenesis is a major factor in psychiatric and neurological disorders that have significantly attracted the attention of neuroscientists. Curcumin is a primary constituent of curcuminoid that exerts several positive pharmacological effects on aberrant neurogenesis. First, it is important to understand the different processes of neurogenesis, and whether their dysfunction promotes etiology as well as the development of many psychiatric and neurological disorders; then investigate mechanisms by which curcumin affects neurogenesis as an active participant in pathophysiological events. Based on scientometric studies and additional extensive research, we explore the mechanisms by which curcumin regulates adult neurogenesis and in turn affects psychiatric diseases, i.e., depression and neurological disorders among them traumatic brain injury (TBI), stroke, Alzheimer's disease (AD), Gulf War Illness (GWI) and Fragile X syndrome (FXS). This review aims to elucidate the therapeutic effects and mechanisms of curcumin on adult neurogenesis in various psychiatric and neurological disorders. Specifically, we discuss the regulatory role of curcumin in different activities of neural stem cells (NSCs), including proliferation, differentiation, and migration of NSCs. This is geared toward providing novel application prospects of curcumin in treating psychiatric and neurological disorders by regulating adult neurogenesis.

Recent Neurotherapeutic Strategies to Promote Healthy Brain Aging: Are we there yet?

Owing to the global exponential increase in population ageing, there is an urgent unmet need to develop reliable strategies to slow down and delay the ageing process. Age-related neurodegenerative diseases are among the main causes of morbidity and mortality in our contemporary society and represent a major socio-economic burden. There are several controversial factors that are thought to play a causal role in brain ageing which are continuously being examined in experimental models. Among them are oxidative stress and brain inflammation which are empirical to brain ageing. Although some candidate drugs have been developed which reduce the ageing phenotype, their clinical translation is limited. There are several strategies currently in development to improve brain ageing. These include strategies such as caloric restriction, ketogenic diet, promotion of cellular nicotinamide adenine dinucleotide (NAD+) levels, removal of senescent cells, 'young blood' transfusions, enhancement of adult neurogenesis, stem cell therapy, vascular risk reduction, and non-pharmacological lifestyle strategies. Several studies have shown that these strategies can not only improve brain ageing by attenuating age-related neurodegenerative disease mechanisms, but also maintain cognitive function in a variety of pre-clinical experimental murine models. However, clinical evidence is limited and many of these strategies are awaiting findings from large-scale clinical trials which are nascent in the current literature. Further studies are needed to determine their long-term efficacy and lack of adverse effects in various tissues and organs to gain a greater understanding of their potential beneficial effects on brain ageing and health span in humans.

The Effect of Polyphenols on Working and Episodic Memory in Non-pathological and Pathological Aging: A Systematic Review and Meta-Analysis

Life expectancy steadily increases, and so do age-associated diseases, leading to a growing population suffering from cognitive decline and dementia. Impairments in working memory (WM) and episodic memory (EM) are associated with an increased risk of developing dementia. While there are no effective pharmacological therapies to preserve or enhance cognition and to slow down the progression from mild memory complaints to dementia so far, plant-based nutrients including polyphenols have been suggested to exert beneficial effects on brain aging. This review studies whether supplementary polyphenols are effective in preserving or enhancing memory in both non-pathological and pathological aging, and whether there are polyphenol efficiency differences between WM and EM. A systematic literature search was conducted and 66 out of 294 randomized clinical trials with 20 participants or more per group, aged 40 years or older were included. These covered a daily intake of 35–1,600 mg polyphenols, e.g., flavonols, flavonoids, isoflovones, anthocyanins, and/or stilbenes, over the course of 2 weeks to 6.5 years duration. In total, around half of the studies reported a significantly improved performance after polyphenol administration compared to control, while three studies reported a worsening of performance, and the remainder did not observe any effects. According to pooled WM and EM meta-analysis of all memory outcomes reported in 49 studies, overall effect size for WM and EM indicated a significant small positive effect on EM and WM with similar estimates (b ~ 0.24, p < 0.001), with large study heterogeneity and significant Funnel asymmetry tests suggesting a positivity bias. These results remained similar when excluding studies reporting extremely large positive effect sizes from the meta-analyses. While Ginkgo biloba and isoflavones did not show benefits in subgroup meta-analyses, those suggested some effects in extracts containing anthocyanins, other flavonoids and resveratrol, again potentially resulting from publication bias. To conclude, a systematic review and meta-analysis indicate that short- to moderate-term polyphenol interventions might improve WM and EM in middle-to older aged adults, however, publication bias in favor of positive results seems likely, rendering definite conclusions difficult. Future studies with larger, more diverse samples and sensitive monitoring of cardiovascular, metabolic and beginning brain pathologies as well as longer follow-up are needed to better understand the impact of age, (beginning) pathologies, gender, and long-term use on polyphenol action.

The Influence of Gut Microbiota on Neurogenesis: Evidence and Hopes

Adult neurogenesis (i.e., the life-long generation of new neurons from undifferentiated neuronal precursors in the adult brain) may contribute to brain repair after damage, and participates in plasticity-related processes including memory, cognition, mood and sensory functions. Among the many intrinsic (oxidative stress, inflammation, and ageing), and extrinsic (environmental pollution, lifestyle, and diet) factors deemed to impact neurogenesis, significant attention has been recently attracted by the myriad of saprophytic microorganismal communities inhabiting the intestinal ecosystem and collectively referred to as the gut microbiota. A growing body of evidence, mainly from animal studies, reveal the influence of microbiota and its disease-associated imbalances on neural stem cell proliferative and differentiative activities in brain neurogenic niches. On the other hand, the long-claimed pro-neurogenic activity of natural dietary compounds endowed with antioxidants and anti-inflammatory properties (such as polyphenols, polyunsaturated fatty acids, or pro/prebiotics) may be mediated, at least in part, by their action on the intestinal microflora. The purpose of this review is to summarise the available information regarding the influence of the gut microbiota on neurogenesis, analyse the possible underlying mechanisms, and discuss the potential implications of this emerging knowledge for the fight against neurodegeneration and brain ageing.

Paeoniflorin Protects against ANIT-Induced Cholestatic Liver Injury in Rats via the Activation of SIRT1-FXR Signaling Pathway

Paeoniflorin (PF), a water-soluble monoterpene glycoside, is initially isolated from the dried roots of Paeonia lactiflora Pall., which has effects on ameliorating cholestasis in our previous study. However, comprehensive approaches for understanding the protective effects and mechanisms underlying cholestatic liver injury from the regulating of bile acid metabolism have not been sufficiently elucidated. This study was aimed to explore the effectiveness as well as potential mechanism of PF on alpha-naphthylisothiocyanate (ANIT)-induced cholestatic liver injury. Rats with cholestasis induced by ANIT was used to evaluate the protective effects and mechanism of PF by regulating SIRT1/FXR and NF-κB/NLRP3 signaling pathway. Rats were intragastrically administrated with ANIT to establish cholestatic liver injury model. Serum levels of ALT, AST, TBA, TBIL, ALP, γ-GT and ALB in rats were detected. The histopathology of the liver of rats was analyzed in vivo. The relative mRNA expression and protein expression levels of IL-18, IL-1β, TNF-α, HO-1, Nrf2, TLR4, NLRP3, Caspase-1, ASC, NF-κB, FXR, and SIRT1 in liver of rats were investigated. The results showed that the serum indexes and the liver histopathology were significantly improved by PF. The overexpression of IL-18, IL-1β, TNF-α, NLRP3, ASC, and Caspase-1 in liver was markedly reduced by PF. Furthermore, PF dramatically increased the mRNA and protein expressions of SIRT1, FXR, HO-1, and Nrf2, but decreased NF-κB p65 and TLR4 levels in liver of rats. Taken together, the protective effects of PF on cholestatic liver injury were possibly related to the activation of the SIRT1/FXR and inhibition of NF-κB/NLRP3 inflammasome signaling pathway. These findings might provide a potential protection for cholestatic liver injury.

The neuroprotective effects of polyphenols, their role in innate immunity and the interplay with the microbiota

Neurodegenerative disorders, particularly in the elderly population, represent one of the most pressing social and health-care problems in the world. Besides the well-established role of both oxidative stress and inflammation, alterations of the immune response have been found to be closely linked to the development of neurodegenerative diseases. Interestingly, various scientific evidence reported that an altered gut microbiota composition may contribute to the development of neuroinflammatory disorders. This leads to the proposal of the concept of the gut-brain-immune axis. In this scenario, polyphenols play a pivotal role due to their ability to exert neuroprotective, immunomodulatory and microbiota-remodeling activities. In the present review, we summarized the available literature to provide a scientific evidence regarding this neuroprotective and immunomodulatory effects and the interaction with gut microbiota of polyphenols and, the main signaling pathways involved that can explain their potential therapeutic application in neurodegenerative diseases.

Momordica Charantia Polysaccharides Attenuates MPP+-Induced Injury in Parkinson’s Disease Mice and Cell Models by Regulating TLR4/MyD88/NF-κB Pathway

Objective. To investigate the potential role of Momordica charantia polysaccharides (MCPs) in Parkinson’s disease (PD) and reveal the molecular mechanism of its function. Method. 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) and 1-methyl-4-phenylpyridinium (1-methyl-4-phenylpyridinium, MPP+) were used to establish PD mice and cell models. The mice and cells were divided into 4 groups: Control group, Control+MCPs group, PD group, and PD+MCPs group. Pole climbing experiment and Rotarod experiment were used to observe the coordination ability of mice. High-performance liquid chromatography and enzyme-linked immunosorbent assay (ELISA) were used to determine neurotransmitters and metabolites, inflammatory factors TNF-α and IL-1β, oxidative stress-related markers SOD, MDA, and GSH in striatum tissues. Western blot was used to determine the protein levels of tyrosine hydroxylase (TH), oxidative stress-related protein Cytochrome C (Cytochrome C), and apoptosis-related proteins Bcl-2, Bax, and cleaved Caspase-3 in tissues and cells. Moreover, flow cytometry, PI staining, and fluorescence were used to observe cell apoptosis. Finally, the activation effect of MCPs on TLR4/MyD88/NF-κB signaling pathway was observed and verified. Results. Compared with the Control group, MPTP treatment can induce brain damage in mice (all $P<0.05$ ), change the metabolic state of neurotransmitters (all $P<0.05$ ), induce inflammation (all $P<0.05$ ), and induce apoptosis and the occurrence of oxidation reaction (all $P<0.05$ ); however, MCPs treatment can significantly reverse the above changes (all $P<0.05$ ). In cell models, studies have found that MCPs can play a protective role by regulating the activation state of TLR4/MyD88/NF-κB pathway. Conclusion. This study found that the application of MCPs therapy can play anti-inflammatory, antioxidative stress, and antiapoptotic effects in PD by regulating the activation of the TLR4/MyD88/NF-κB pathway.

Geroprotective potential of in vitro bioactive compounds isolated from yarrow (Achilleae millefolii L.) cell cultures

Introduction. There is an urgent need for geroprotectors that prevent premature aging, especially antioxidants of plant origin. Due to the shortage of medicinal plant materials, scientists look for alternative sources of bioactive compounds of phenolic nature, for example, cell cultures and organs of higher plants. This paper describes a study of the geroprotective potential of in vitro bioactive compounds isolated from yarrow (Achilleae millefolii L.) cell cultures. Study objects and methods. Callus, suspension and hairy root cultures of A. millefolii were obtained by in vitro cultivation on modified nutrient media. High performance liquid chromatography (HPLC) was used to analyze the composition of the cell cultures and ethanol extracts. The extracts’ antimicrobial activity was studied by the disk diffusion method and their antioxidant activity was measured based on titration of a potassium permanganate solution. Results and discussion. The biomass of all yarrow cell cultures contained essential oils, flavonoids, glycosides, phenolic acids, carotenoids, as well as vitamins C and E. The suspension culture had a higher content of essential oils, flavonoids and glycosides than the callus and hairy root cultures. The extracts of the A. millefolii suspension culture also contained geroprotectors – phenylpropanoids, flavonoids, and simple phenols, with a prevalence of caffeic acid, cynaroside, 4,5-dicofeylquinic acid, apigenin, and luteolin. In addition, HPLC revealed the presence of cumic aldehyde, umbelliferone, 3-caffeylquinic acid, and caffeic acid – the bioactive compounds previously not reported in yarrow. In vitro experiments with the extracts proved their antimicrobial and antioxidant activity. Conclusion. The complex of bioactive compounds isolated from the biomass of yarrow suspension culture provides this plant with potential geroprotective properties. Thus, yarrow can be used to create nutraceuticals that prevent premature aging.

Polyphenols and Cognition In Humans: An Overview of Current Evidence from Recent Systematic Reviews and Meta-Analyses

BACKGROUND

There is increasing interest in the impact of dietary influences on the brain throughout the lifespan, ranging from improving cognitive development in children through to attenuating ageing related cognitive decline and reducing risk of neurodegenerative diseases. Polyphenols, phytochemicals naturally present in a host of fruits, vegetables, tea, cocoa and other foods, have received particular attention in this regard, and there is now a substantial body of evidence from experimental and epidemiological studies examining whether their consumption is associated with cognitive benefits.

OBJECTIVE

The purpose of this overview is to synthesise and evaluate the best available evidence from two sources, namely meta-analyses and systematic reviews, in order to give an accurate reflection of the current evidence base for an association between polyphenols and cognitive benefits.

METHOD

Four meta-analyses and thirteen systematic reviews published between 2017-2020 were included, and were categorised according to whether they reviewed specific polyphenol-rich foods and classes or all polyphenols. A requirement for inclusion was assessment of a behavioural cognitive outcome in humans.

RESULTS

A clear and consistent theme emerged that whilst there is support for an association between polyphenol consumption and cognitive benefits, this conclusion is tentative, and by no means definitive. Considerable methodological heterogeneity was repeatedly highlighted as problematic such that the current evidence base does not support reliable conclusions relating to efficacy of specific doses, duration of treatment, or sensitivity in specific populations or certain cognitive domains. The complexity of multiple interactions between a range of direct and indirect mechanisms of action is discussed.

CONCLUSIONS

Further research is required to strengthen the reliability of the evidence base.

Synthesis of New Tyrosol-Based Phosphodiester Derivatives: Effect on Amyloid β Aggregation and Metal Chelation Ability

Alzheimer's disease (AD) is a multifactorial pathology that requires multifaceted agents able to address its peculiar nature. Increasing evidence has shown that aggregation of amyloid β (Aβ) and oxidative stress are strictly interconnected, and their modulation might have a positive and synergic effect in contrasting AD-related impairments. Herein, a new and efficient fragment-based approach towards tyrosol phosphodiester derivatives (TPDs) has been developed starting from suitable tyrosol building blocks and exploiting the well-established phosphoramidite chemistry. The antioxidant activity of new TPDs has been tested as well as their ability to inhibit Aβ protein aggregation. In addition, their metal chelating ability has been evaluated as a possible strategy to develop new natural-based entities for the prevention or therapy of AD. Interestingly, TPDs containing a catechol moiety have demonstrated highly promising activity in inhibiting the aggregation of Aβ₄₀ and a strong ability to chelate biometals such as Cu^II and Zn^II .

Neurophysiological Effects of Whole Coffee Cherry Extract in Older Adults with Subjective Cognitive Impairment: A Randomized, Double-Blind, Placebo-Controlled, Cross-Over Pilot Study

Bioactive plant-based compounds have shown promise as protective agents across multiple domains including improvements in neurological and psychological measures. Methodological challenges have limited our understanding of the neurophysiological changes associated with polyphenol-rich supplements such as whole coffee cherry extract (WCCE). In the current study, we (1) compared 100 mg of WCCE to a placebo using an acute, randomized, double-blind, within-subject, cross-over design, and we (2) conducted a phytochemical analysis of WCCE. The primary objective of the study was to determine the neurophysiological and behavioral changes that resulted from the acute administration of WCCE. We hypothesized that WCCE would increase brain-derived neurotrophic factor (BDNF) and glutamate levels while also increasing neurofunctional measures in cognitive brain regions. Furthermore, we expected there to be increased behavioral performance associated with WCCE, as measured by reaction time and accuracy. Participants underwent four neuroimaging scans (pre- and post-WCCE and placebo) to assess neurofunctional/metabolic outcomes using functional magnetic resonance imaging and magnetic resonance spectroscopy. The results suggest that polyphenol-rich WCCE is associated with decreased reaction time and may protect against cognitive errors on tasks of working memory and response inhibition. Behavioral findings were concomitant with neurofunctional changes in structures involved in decision-making and attention. Specifically, we found increased functional connectivity between the anterior cingulate and regions involved in sensory and decision-making networks. Additionally, we observed increased BDNF and an increased glutamate/gamma-aminobutyric acid (GABA) ratio following WCCE administration. These results suggest that WCCE is associated with acute neurophysiological changes supportive of faster reaction times and increased, sustained attention.

Effects of Fruit and Vegetable-Based Nutraceutical on Cognitive Function in a Healthy Population: Placebo-Controlled, Double-Blind, and Randomized Clinical Trial

There is scientific evidence of the positive effect of polyphenols from plant foods on cognition, but not enough is known about the synergistic effect when multiple polyphenols are consumed and even less in a healthy non-elderly population. The aim of the present study is to investigate the possible effects of improvements in cognitive function in healthy people as a preparation based on micronized fruit and vegetables consumed. One hundred and eight subjects were selected, stratified by sex in the control intervention group (n = 53) and placebo (n = 55). Volunteers completed the study after two 16-week periods of consumption with a 4-week wash period between each phase. At the beginning and the end of each phase, volunteers performed the Stroop, TESEN, and RIST tests for the measurement of different cognitive function patterns. The results revealed statistically significant differences in all the variables of the tests carried out, especially compared with the placebo. Specially, the results obtained in the Stroop and TESEN test, in addition to the processing speed even with semantic interferences, were markedly better after the treatment with the product under study. Moreover, the consumption of the product under study clearly improves short-term memory, verbal and non-verbal, according to the results obtained in the RIST test. The results showed an improvement in executive function in terms of short-term memory, working memory, selective and sustained attention, and speed of processing.

The role of Nrf2 in neural stem/progenitors cells: From maintaining stemness and self-renewal to promoting differentiation capability and facilitating therapeutic application in neurodegenerative disease

Neurodegenerative diseases (NDs) cause progressive loss of neurons in nervous system. NDs are categorized as acute NDs such as stroke and head injury, besides chronic NDs including Alzheimer's, Parkinson's, Huntington's diseases, Friedreich's Ataxia, Multiple Sclerosis. The exact etiology of NDs is not understood but oxidative stress, inflammation and synaptic dysfunction are main hallmarks. Oxidative stress leads to free radical attack on neural cells which contributes to protein misfolding, glia cell activation, mitochondrial dysfunction, impairment of DNA repair system and subsequently cellular death. Neural stem cells (NSCs) support adult neurogenesis in nervous system during injuries which is limited to certain regions in brain. NSCs can differentiate into the neurons, astrocytes or oligodendrocytes. Impaired neurogenesis and inadequate induction of neurogenesis are the main obstacles in treatment of NDs. Protection of neural cells from oxidative damages and supporting neurogenesis are promising strategies to treat NDs. Nuclear factor-erythroid 2-related factor 2 (Nrf2) is a transcriptional master regulator that maintains the redox homeostasis in cells by provoking expression of antioxidant, anti-inflammatory and cytoprotective genes. Nrf2 can strongly influence the NSCs function and fate determination by reducing levels of reactive oxygen species in benefit of NSC survival and neurogenesis. In this review we will summarize the role of Nrf2 in NSC function, and exogenous and endogenous therapeutic strategies in treatment of NDs.

Momordica charantia polysaccharides modulate the differentiation of neural stem cells via SIRT1/Β-catenin axis in cerebral ischemia/reperfusion

BACKGROUND

Stroke is the leading cause of long-term motor disability and cognitive impairment. Recently, neurogenesis has become an attractive strategy for the chronic recovery of stroke. It is important to understand the molecular mechanism that promotes neural stem cell (NSC) neurogenesis for future NSC-based therapies. Our previous study showed that Momordica charantia polysaccharides (MCPs) exerted neuroprotective effects on stroke via their anti-oxidant and anti-inflammation activities. However, it remains unknown whether MCPs promote NSC neurogenesis after cerebral ischemic/reperfusion injury (IRI).

METHODS

We investigated MCPs' function in differentiation of neural stem cells (NSCs) in vivo and in vitro experiments. Based on a middle cerebral artery occlusion (MCAO) rat model, the effect of MCPs on neuronal differentiation after MCAO was analyzed. Primary NSCs and neural stem cell line C17.2 were cultured and subjected to glutamate stimulation to establish the cell model of IRI. We evaluated the effect of MCPs on NSC differentiation in IRI cell model by Western blot and immunofluorescence staining. The SIRT1 activity of NSCs post glutamate stimulation was also evaluated by CELL SIRT1 COLORIMETRY ASSAY KIT. In addition, molecular mechanism was clarified by employing the activator and inhibitor of SIRT1.

RESULTS

MCPs had no effects on the differentiation of neural stem cells under physiological conditions while shifted NSC differentiation potential from the gliogenic to neurogenic lineage under pathological conditions. Activation of SIRT1 with MCPs was responsible for the neuronal differentiation of C17.2-NSCs. The neuronal differentiation effect of MCPs was attributed to upregulation SIRT1-mediated deacetylation of β-catenin. MCP-induced deacetylation via SIRT1 promoted nuclear accumulation of β-catenin in NSCs.

CONCLUSION

Our findings indicate that the deacetylation of β-catenin by SIRT1 represents a critical mechanism of action of MCPs in promoting NSC neuronal differentiation. It provides an improved understanding of molecular mechanism underlying neuroprotective effects of MCPs in IRI, indicating its potential role on treating ischemic stroke especially chronic recovery.

Lipid Peroxidation and Antioxidant Supplementation in Neurodegenerative Diseases: A Review of Human Studies

Being characterized by progressive and severe damage in neuronal cells, neurodegenerative diseases (NDDs) are the major cause of disability and morbidity in the elderly, imposing a significant economic and social burden. As major components of the central nervous system, lipids play important roles in neural health and pathology. Disturbed lipid metabolism, particularly lipid peroxidation (LPO), is associated with the development of many NDDs, including Alzheimer’s disease (AD), Parkinson’s disease (PD), and amyotrophic lateral sclerosis (ALS), all of which show elevated levels of LPO products and LPO-modified proteins. Thus, the inhibition of neuronal oxidation might slow the progression and reduce the severity of NDD; natural antioxidants, such as polyphenols and antioxidant vitamins, seem to be the most promising agents. Here, we summarize current literature data that were derived from human studies on the effect of natural polyphenols and vitamins A, C, and E supplementation in patients with AD, PD, and ALS. Although these compounds may reduce the severity and slow the progression of NDD, research gaps remain in antioxidants supplementation in AD, PD, and ALS patients, which indicates that further human studies applying antioxidant supplementation in different forms of NDDs are urgently needed.

Nuclear receptor TLX may be through regulating the SIRT1/NF-κB pathway to ameliorate cognitive impairment in chronic cerebral hypoperfusion

BACKGROUND

Chronic cerebral hypoperfusion (CCH) is a common pathophysiological mechanism in neurodegenerative diseases, such as Alzheimer's disease and vascular dementia. The orphan nuclear receptor TLX plays an important role in neural development, adult neurogenesis and cognition. The aim of this study was to investigate the neuroprotective effects of TLX on cognitive dysfunction, hippocampal neurogenesis and neuroinflammation in a rat model of CCH and to assess the possible mechanisms.

METHODS

Permanent bilateral common carotid artery occlusion (2-VO) was used to establish a model of CCH. Stereotaxic injection of an adeno-associated virus vector expressing TLX was used to overexpress TLX in the hippocampus. Cognitive function was evaluated by the Morris Water Maze test. Immunofluorescent staining was used to assess hippocampal neurogenesis. The effects of overexpression of TLX on SIRT1 and inflammatory cytokines were analyzed with qRT-PCR and western blot.

RESULT

After 2-VO, CCH rats exhibited cognitive impairment and reduction of hippocampal TLX levels. Overexpression of TLX ameliorated cognitive impairments with increasing number of BrdU + cells and BrdU + NeuN + cells in DG. Furthermore, TLX rescued the reduced SIRT1 usually induced by CCH. Additionally, TLX also inhibited the expression of inflammatory cytokines such as NF-κB and IL-1β.

CONCLUSIONS

The present findings suggested that TLX exerted protective effects against cognitive deficits induced by CCH. The possible mechanisms of TLX may be through regulating the SIRT1/NF-κB pathway, promoting hippocampal neurogenesis and inhibiting the neuroinflammatory response.

Polyphenol intake and cognitive decline in the Seguimiento Universidad de Navarra (SUN) Project

The global growing rates of cognitive decline and dementia, together with the absence of curative therapies for these conditions, support the interest in researching potential primary prevention interventions, with particular focus on dietary habits. The aim was to assess the association between polyphenol intake and 6-year change in cognitive function in the 'Seguimiento Universidad de Navarra' (SUN) Project, a Spanish prospective cohort study. Changes (final - initial) in cognitive function were evaluated in a subsample of 806 participants (mean age 66 (sd 5) years, 69·7 % male) of the SUN Project using the validated Spanish Telephone Interview for Cognitive Status-modified score. Polyphenol intake was derived from a validated semi-quantitative FFQ and matching food composition data from the Phenol-Explorer database. Multivariable linear regression models were used to evaluate the association between total polyphenol intake, polyphenol subclasses and cognitive changes. No significant association between total polyphenol intake and changes in cognitive function was found. However, a higher intake of lignans (βQuintile (Q) 5 v. Q1 0·81; 95 % CI 0·12, 1·51; Ptrend = 0·020) and stilbenes (βQ5 v. Q1 0·82; 95 % CI 0·15, 1·49; Ptrend = 0·028) was associated with more favourable changes in cognitive function over time, particularly with respect to immediate memory and language domains. Olive oil and nuts were the major sources of variability in lignan intake, and wine in stilbene intake. The results suggest that lignan and stilbene intake was associated with improvements in cognitive function.

A novel salvianolic acid A analog with resveratrol structure and its antioxidant activities in vitro and in vivo

E-DRS is a novel salvianolic acid A (SAA) analog, which was synthesized from resveratrol (RES) and methyldopate. Its structure is similar to that of SAA, but the 3',4'-dihydroxy-trans-stilbene group and the ester structure in SAA were replaced by the RES structure and an amine group, respectively. E-DRS scavenged free oxygen radicals effectively, including superoxide anion (ascorbic acid > E-DRS > SAA ≥ rutin > RES) and DPPH radical (rutin > E-DRS ≥ ascorbic acid > SAA > RES), and exhibited powerful total antioxidant capacity (ascorbic acid > E-DRS > SAA ≥ rutin > RES) in vitro. Furthermore, oral administration of E-DRS dose-dependently and significantly decreased CCl₄ -induced oxidative stress in mice as indicated by the decreased content of hepatic malondialdehyde (MDA). In addition, oral administration of E-DRS also increased the content of nonenzymatic antioxidant glutathione (GSH) and the activity of antioxidant enzymes such as catalase (CAT) and superoxide dismutase (SOD) in the liver of mice. All these results demonstrated that E-DRS had good antioxidant activities both in vitro and in vivo, and could be a potential antioxidant agent after further optimization and evaluation.

Sirtuins, brain and cognition: A review of resveratrol effects

Sirtuins (SIRTs) are a protein family with high preservation degree among evolutionary scale. SIRTs are histone deacetylases regulatory enzymes of genetic material deeply involved in numerous physiological tasks including metabolism, brain function and aging. Mammals sirtuins comprise seven enzymatic components (SIRT1–SIRT7). The highest studied sirtuin is SIRT1, which plays an essential position in the prevention and evolution of neuro-disorders. Resveratrol (3,5,4-trihydroxystylbene) (RSV) is a polyphenol, which belongs to a family compounds identified as stilbenes, predominantly concentrated in grapes and red wine. RSV is the must studied Sirtuin activator and is used as food supplementary compound. Resveratrol exhibits strong antioxidant activity, reducing free radicals, diminishing quinone-reductase-2 activity and exerting positive regulation of several endogenous enzymes. Resveratrol is also able to inhibit pro-inflammatory factors, reducing the stimulation of the nuclear factor kB (NF-kB) and the release of endogenous cytokines. Resveratrol treatment can modulate multiple signaling pathway effectors related to programmed cell death, cell survival, and synaptic plasticity. In this context, the present review looks over news and the role of Sirtuins activation and resveratrol effects on modulating target genes, cognition and neurodegenerative disorders.

The Pluripotency Factor Nanog Protects against Neuronal Amyloid β-Induced Toxicity and Oxidative Stress through Insulin Sensitivity Restoration

Amyloid β (Aβ) is a peptide fragment of the amyloid precursor protein that triggers the progression of Alzheimer's Disease (AD). It is believed that Aβ contributes to neurodegeneration in several ways, including mitochondria dysfunction, oxidative stress and brain insulin resistance. Therefore, protecting neurons from Aβ-induced neurotoxicity is an effective strategy for attenuating AD pathogenesis. Recently, applications of stem cell-based therapies have demonstrated the ability to reduce the progression and outcome of neurodegenerative diseases. Particularly, Nanog is recognized as a stem cell-related pluripotency factor that enhances self-renewing capacities and helps reduce the senescent phenotypes of aged neuronal cells. However, whether the upregulation of Nanog can be an effective approach to alleviate Aβ-induced neurotoxicity and senescence is not yet understood. In the present study, we transiently overexpressed Nanog-both in vitro and in vivo-and investigated the protective effects and underlying mechanisms against Aβ. We found that overexpression of Nanog is responsible for attenuating Aβ-triggered neuronal insulin resistance, which restores cell survival through reducing intracellular mitochondrial superoxide accumulation and cellular senescence. In addition, upregulation of Nanog expression appears to increase secretion of neurotrophic factors through activation of the Nrf2 antioxidant defense pathway. Furthermore, improvement of memory and learning were also observed in rat model of Aβ neurotoxicity mediated by upregulation of Nanog in the brain. Taken together, our study suggests a potential role for Nanog in attenuating the neurotoxic effects of Aβ, which in turn, suggests that strategies to enhance Nanog expression may be used as a novel intervention for reducing Aβ neurotoxicity in the AD brain.

Polyphenols as Caloric-Restriction Mimetics and Autophagy Inducers in Aging Research

It has been thought that caloric restriction favors longevity and healthy aging where autophagy plays a vital role. However, autophagy decreases during aging and that can lead to the development of aging-associated diseases such as cancer, diabetes, neurodegeneration, etc. It was shown that autophagy can be induced by mechanical or chemical stress. In this regard, various pharmacological compounds were proposed, including natural polyphenols. Apart from the ability to induce autophagy, polyphenols, such as resveratrol, are capable of modulating the expression of pro- and anti-apoptotic factors, neutralizing free radical species, affecting mitochondrial functions, chelating redox-active transition metal ions, and preventing protein aggregation. Moreover, polyphenols have advantages compared to chemical inducers of autophagy due to their intrinsic natural bio-compatibility and safety. In this context, polyphenols can be considered as a potential therapeutic tool for healthy aging either as a part of a diet or as separate compounds (supplements). This review discusses the epigenetic aspect and the underlying molecular mechanism of polyphenols as an anti-aging remedy. In addition, the recent advances of studies on NAD-dependent deacetylase sirtuin-1 (SIRT1) regulation of autophagy, the role of senescence-associated secretory phenotype (SASP) in cells senescence and their regulation by polyphenols have been highlighted as well. Apart from that, the review also revised the latest information on how polyphenols can help to improve mitochondrial function and modulate apoptosis (programmed cell death).

Grape Polyphenols Ameliorate Muscle Decline Reducing Oxidative Stress and Oxidative Damage in Aged Rats

A large number of studies have demonstrated the implication of oxidative stress (OxS) in the pathogenesis of ageing-related muscle decline and atrophy. The key mechanism is related to the OxS-induced production of free radicals, with the consequent increase in oxidative damage, resulting in affected muscle quality and strength. The present study aimed to evaluate the efficacy of a grape polyphenol-based nutraceutical formulation (Taurisolo^®) in reducing the OxS in muscle of aged rats. A group of 16 aged (20 months) rats were orally administered with Taurisolo^® (n = 8; 100 mg/kg Taurisolo^®) or placebo (n = 8; 50 mg/kg maltodextrin); an additional group of eight young (three months) rats were also treated with placebo. All the treatments were orally administered for 30 days. The activities of antioxidant enzymes, the levels of malondialdehyde (MDA) and nitrotyrosine (N-Tyr) and the expression of OxS- and inflammation-related genes were evaluated on the gastrocnemius muscle. In muscle samples of the treated-group, increased activity of antioxidant enzymes, reduced MDA and N-Tyr levels and increased expression of antioxidant and anti-inflammatory genes were observed in respect to the placebo. Data herein presented suggest that the chronic treatment with Taurisolo^® significantly reduces oxidative damage and improves muscle performance in aged rats.

Interaction Between Neurogenic Stimuli and the Gene Network Controlling the Activation of Stem Cells of the Adult Neurogenic Niches, in Physiological and Pathological Conditions

In the adult mammalian brain new neurons are continuously generated throughout life in two niches, the dentate gyrus of the hippocampus and the subventricular zone. This process, called adult neurogenesis, starts from stem cells, which are activated and enter the cell cycle. The proliferative capability of stem cells progressively decreases during aging. The population of stem cells is generally quiescent, and it is not clear whether the potential for stem cells to expand is limited, or whether they can expand and then return to quiescence, remaining available for further activation. Certain conditions may deregulate stem cells quiescence and self-renewal. In fact we discuss the possibility of activation of stem cells by neurogenic stimuli as a function of the intensity of the stimulus (i.e., whether this is physiological or pathological), and of the deregulation of the system (i.e., whether the model is aged or carrying genetic mutations in the gene network controlling quiescence). It appears that when the system is aged and/or carrying mutations of quiescence-maintaining genes, preservation of the quiescent state of stem cells is more critical and stem cells can be activated by a neurogenic stimulus which is ineffective in normal conditions. Moreover, when a neurogenic stimulus is in itself a cause of brain damage (e.g., kainic acid treatment) the activation of stem cells occurs bypassing any inhibitory control. Plausibly, with strong neurogenic stimuli, such as kainic acid injected into the dentate gyrus, the self-renewal capacity of stem cells may undergo rapid exhaustion. However, the self-renewal capability of stem cells persists when normal stimuli are elicited in the presence of a mutation of one of the quiescence-maintaining genes, such as p16Ink4a, p21Cip1 or Btg1. In this case, stem cells become promptly activated by a neurogenic stimulus even during aging. This indicates that stem cells retain a high proliferative capability and plasticity, and suggests that stem cells are protected against the response to stimulus and are resilient to exhaustion. It will be interesting to assess at which functional degree of deregulation of the quiescence-maintaining system, stem cells will remain responsive to repeated neurogenic stimuli without undergoing exhaustion of their pool.

Chronic Polyphenon-60 or Catechin Treatments Increase Brain Monoamines Syntheses and Hippocampal SIRT1 Levels Improving Cognition in Aged Rats

Polyphenolic compounds from green tea have great interest due to its large CONSUMPTION and therapeutic potential on the age-associated brain decline. The current work compares a similar dose regimen of a whole-green-tea extract and catechin in old rats over the course of 36 days. Results showed a significant improvement in visuo-spatial working memory and episodic memory of old rats after polyphenolic compounds administration assessed by behavioral tests. No effects were observed on the age-associated motor coordination decline. Statistically, results were correlated with significant improvements, mainly in hippocampal and striatal noradrenergic and serotonergic systems, but also with the striatal dopaminergic system. Both polyphenolic treatments also reverted the age-associated reduction of the neuroinflammation by modulating protein sirtuin 1 (SIRT1) expression in hippocampus, but no effects were observed in the usual reduction of the histone-binding protein RBAP46/48 protein linked to aging. These results are in line with previous ones obtained with other polyphenolic compounds, suggesting a general protective effect of all these compounds on the age-associated brain decline, pointing to a reduction of the oxidative stress and neuroinflammatory status reduction as the leading mechanisms. Results also reinforce the relevance of SIRT1-mediated mechanism on the neuroprotective effect and rule out the participation of RBAP46/48 protein.

Designing multiple bioactives loaded emulsions for the formulations for diets of elderly

In this study, a stable double emulsion loaded with essential bioactives for the elderly was prepared using a two-step mechanical emulsification process.

Nutrients and neurogenesis: the emerging role of autophagy and gut microbiota

Adult neurogenesis, the generation of mature functional neurons from neural stem cells in specific regions of the adult mammalian brain, is implicated in brain physiology, neurodegeneration and mood disorders. Among the many intrinsic and extrinsic factors that modulate neurogenic activity, the role of nutrients, energy metabolism, and gut microbiota has recently emerged. It is increasingly evident that excessive calorie intake accelerates the age-dependent decline of neurogenesis, while calorie restriction and physical exercise have the opposite effect. Mechanistically, nutrient availability could affect neurogenesis by modulating autophagy, a cell-rejuvenating process, in neural stem cells. In parallel, diet can alter the composition of gut microbiota thus impacting the intestine-neurogenic niche communication. These exciting breakthroughs are here concisely reviewed.

Cognitive short- and long-term effects of coffee cherry extract in older adults with mild cognitive decline

There has been increasing interest in food- and dietary supplement-based materials that may support healthy cognition. However, few studies have quantitatively measured bioavailability, bioactivity, or cognitive short- and long-term effects of these materials against placebo. Earlier clinical studies reported ability of coffee cherry extract (CCE) to a.) reduce levels of reactive oxygen species (ROS) in human blood and b.) to increase serum and exosomal levels of brain-derived neurotrophic factor (BDNF), a neuroprotein essential for neurogenesis. Here, we examined CCE influence on cognitive performance. Seventy-one adults with mild cognitive decline completed this double blind, randomized, placebo-controlled, 28-day regimen. Participants engaged in a cognitive challenge that involved working memory processes. Our results suggest that effects of CCE were notable during the first week and persisted throughout the study period. Specifically, participants on the CCE regimens had significant reductions in reaction time compared to placebo when comparing baseline to days 7 and 28 (p = 0.040, partial η²  = 0.130). A main effect of group was not identified for accuracy; however, strong trends were noted between the placebo group and two of the three CCE groups. These results suggest CCE, when taken in the morning or twice per day, is associated with improvements in reaction times and trends toward indications of improved accuracy. Although further research is required, these observations may be indicative of underlying processes such as increased processing speed, sustained attention, and/or focus.

Diet-Related Metabolites Associated with Cognitive Decline Revealed by Untargeted Metabolomics in a Prospective Cohort

SCOPE

Untargeted metabolomics may reveal preventive targets in cognitive aging, including within the food metabolome.

METHODS AND RESULTS

A case-control study nested in the prospective Three-City study includes participants aged ≥65 years and initially free of dementia. A total of 209 cases of cognitive decline and 209 controls (matched for age, gender, education) with slower cognitive decline over up to 12 years are contrasted. Using untargeted metabolomics and bootstrap-enhanced penalized regression, a baseline serum signature of 22 metabolites associated with subsequent cognitive decline is identified. The signature includes three coffee metabolites, a biomarker of citrus intake, a cocoa metabolite, two metabolites putatively derived from fish and wine, three medium-chain acylcarnitines, glycodeoxycholic acid, lysoPC(18:3), trimethyllysine, glucose, cortisol, creatinine, and arginine. Adding the 22 metabolites to a reference predictive model for cognitive decline (conditioned on age, gender, education and including ApoE-ε4, diabetes, BMI, and number of medications) substantially increases the predictive performance: cross-validated Area Under the Receiver Operating Curve = 75% [95% CI 70-80%] compared to 62% [95% CI 56-67%].

CONCLUSIONS

The untargeted metabolomics study supports a protective role of specific foods (e.g., coffee, cocoa, fish) and various alterations in the endogenous metabolism responsive to diet in cognitive aging.

The protective effect of lithocholic acid on the intestinal epithelial barrier is mediated by the vitamin D receptor via a SIRT1/Nrf2 and NF-κB dependent mechanism in Caco-2 cells

Lithocholic acid (LCA) is both a secondary bile acid and a vitamin D receptor (VDR) ligand. The VDR is activated by 1,25-dihydroxy vitamin D₃ and plays an important role in maintaining integrity of the intestinal mucosal barrier. LCA can also substitute for vitamin D to carry out the in vivo functions of vitamin D. However, it is unclear whether activation of the VDR by LCA affects mucosal barrier function. In the present study, we researched the protective effect of LCA on tumor necrosis factor-alpha (TNF-α)-induced intestinal epithelial barrier dysfunction in Caco-2 cells of the human epithelial intestinal adenocarcinoma cell line. Caco-2 cell monolayers were pretreated with LCA and then exposed to 100 ng/mL TNF-α. The results showed that LCA alleviated the decrease in transepithelial electrical resistance and the increase in FITC-Dextran flux induced by TNF-α. LCA ameliorated the TNF-α-induced decrease in protein expression and distribution of ZO-1, E-cadherin, Occludin, and Claudin-1, which are tight junction markers. Additionally, the LCA treatment effectively counteracted TNF-α-mediated downregulation of silent information regulator 1 (SIRT1), nuclear factor erythroid2-related factor 2 (Nrf2), and heme oxygenase-1, which are related to oxidative stress. Increases in NF-κB p-p65 and p-IκB-α induced by TNF-α were significantly inhibited by LCA. Considering all these, the present study indicates that LCA has a significant protective effect on TNF-α-induced injury of intestinal barrier function through the VDR and suggests that suppressing NF-κB signaling and activating the SIRT1/Nrf2 pathway might be one of the mechanisms underlying the protective effect of LCA.

Modulation of Nerve Cell Differentiation: Role of Polyphenols and of Contactin Family Components

In this study the mechanisms are explored, which modulate expression and function of cell surface adhesive glycoproteins of the Immunoglobulin Supergene Family (IgSF), and in particular of its Contactin subset, during neuronal precursor developmental events. In this context, a specific topic concerns the significance of the expression profile of such molecules and their ability to modulate signaling pathways activated through nutraceuticals, in particular polyphenols, administration. Both in vitro and in vivo approaches are chosen. As for the former, by using as a model the human SH-SY5Y neuroblastoma line, the effects of grape seed polyphenols are evaluated on proliferation and commitment/differentiation events along the neuronal lineage. In SH-SY5Y cell cultures, polyphenols were found to counteract precursor proliferation while promoting their differentiation, as deduced by studying their developmental parameters through the expression of cell cycle and neuronal commitment/differentiation markers as well as by measuring neurite growth. In such cultures, Cyclin E expression and BrdU incorporation were downregulated, indicating reduced precursor proliferation while increased neuronal differentiation was inferred from upregulation of cell cycle exit (p27^–Kip) and neuronal commitment (NeuN) markers as well as by measuring neurite length through morphometric analysis. The polyphenol effects on developmental parameters were also explored in vivo, in cerebellar cortex, by using as a model the TAG/F3 transgenic line, which undergoes delayed neural development as a consequence of Contactin1 adhesive glycoprotein upregulation and premature expression under control of the Contactin2 gene (Cntn-2) promoter. In this transgenic line, a Notch pathway activation is known to occur and polyphenol treatment was found to counteract such an effect, demonstrated through downregulation of the Hes-1 transcription factor. Polyphenols also downregulated the expression of adhesive glycoproteins of the Contactin family themselves, demonstrated for both Contactin1 and Contactin2, indicating the involvement of changes in the expression of the underlying genes in the observed phenotype. These data support the hypothesis that the complex control exerted by polyphenols on neural development involves modulation of expression and function of the genes encoding cell adhesion molecules of the Contactin family and of the associated signaling pathways, indicating potential mechanisms whereby such compounds may control neurogenesis.

Diet-induced hypothalamic dysfunction and metabolic disease, and the therapeutic potential of polyphenols

BACKGROUND

The prevalence of obesity and metabolic diseases continues to rise globally. The increased consumption of unhealthy energy-rich diets that are high in fat and sugars results in oxidative stress and inflammation leading to hypothalamic dysfunction, which has been linked with these diseases. Conversely, diets rich in polyphenols, which are phytochemicals known for their antioxidant and anti-inflammatory properties, are associated with a reduced risk for developing metabolic diseases.

SCOPE OF REVIEW

This review provides an overview of the effects of polyphenols against diet-induced hypothalamic dysfunction with respect to neural inflammation and mitochondrial dysfunction. Results show that polyphenols ameliorate oxidative stress and inflammation within the hypothalamus, thereby improving leptin signaling and mitochondrial biogenesis. Furthermore, they protect against neurodegeneration by decreasing the production of reactive oxygen species and enhancing natural antioxidant defense systems.

MAJOR CONCLUSIONS

The potential of polyphenols as nutraceuticals against hypothalamic inflammation, mitochondrial dysfunction, and neurodegeneration could hold tremendous value. With hypothalamic inflammation increasing naturally with age, the potential to modulate these processes in order to extend longevity is exciting and warrants exploration. The continued escalation of mental health disorders, which are characterized by heightened neuronal inflammation, necessitates the furthered investigation into polyphenol therapeutic usage in this regard.

Anti-cancer effects of polyphenols via targeting p53 signaling pathway: updates and future directions

The anticancer effects of polyphenols are ascribed to several signaling pathways including the tumor suppressor gene tumor protein 53 (p53). Expression of endogenous p53 is silent in various types of cancers. A number of polyphenols from a wide variety of dietary sources could upregulate p53 expression in several cancer cell lines through distinct mechanisms of action. The aim of this review is to focus the significance of p53 signaling pathways and to provide molecular intuitions of dietary polyphenols in chemoprevention by monitoring p53 expression that have a prominent role in tumor suppression.