Polyphenols journey through blood-brain barrier towards neuronal protection

Extended recommendations on the nomenclature for microbial catabolites of dietary (poly)phenols, with a focus on isomers

There is an increasing body of evidence indicating that phenolic compounds derived from microbiota-mediated breakdown of dietary (poly)phenolics in the colon are at least partially responsible for the beneficial effects of a plant-based diet. Investigating the role of these catabolites and defining their particular biological effects is challenging due to the complex microbial pathways and the diversity of structures that are produced. When reviewing the data this is further exacerbated by the inconsistency and lack of standardization in naming the microbial phenolics. Here we update the nomenclature of colonic catabolites of dietary (poly)phenols, extending the proposals of Kay et al. (Am. J. Clin. Nutr., 2020, 112, 1051-1068, DOI: 10.1093/ajcn/nqaa204), by providing additional structures, and addressing the difficulties that can arise when investigating regioisomers and stereoisomers, where subtle differences in structure can have a substantial impact on bioactivity. The information provided will help to better harmonize the literature, facilitate data retrieval and provide a reference for researchers in several fields, especially nutrition and biochemistry.

Antioxidant Potential of Selected Apiaceae Plant Extracts: A Study Focused on the Chemical Composition and Neuroprotective Effect of Coriandrum sativum L. Extract Against Lead (Pb)-Induced Neurotoxicity in Rats

Lead is a common environmental pollutant. It can affect several body systems including the central nervous system (CNS). Lead can disrupt the nervous system by different mechanisms including oxidative stress, inflammation, disruption of neurotransmission, and aberrant autophagy. Apiaceous species have been used traditionally as food flavoring and medicine, representing a rich source of bioactive compounds. In the current study, the antioxidant power of four Apiaceous extracts (Foeniculum vulgare L., Pimpinella anisum L., Coriandrum sativum L., and Cuminum cyminum L.) was evaluated. Additionally, the metabolite profiles of the selected species were comprehensively investigated by untargeted liquid chromatography electrospray ionization tandem mass spectrometry (LC/ESI-MS/MS) coupled to chemometry. Coriander (Coriandrum sativum L.) extract showed the highest radical scavenging activity and reducing power. Coriander was further subjected to in vivo evaluation of its protective effect against Lead (Pb)-induced neurotoxicity. Administration of coriander extracts improved the short- and long-term memory performance and decreased hippocampal Pb content in Pb-intoxicated rats. Moreover, it attenuated hippocampal oxidative stress, neurochemical changes, and exhibited anti-inflammatory effect in the hippocampal tissue. Further, coriander extracts attenuated Pb inhibitory effect on the mammalian target of Rapamycin (mTORC1) pathway resulting in upregulation of Phospho-p70 S6 Kinase (P-P70S6K) and Phospho-S6 Ribosomal Protein (PS6) and downregulation of Beclin-1. Additionally, some selected coriander ingredients were subjected to molecular docking to examine their regulatory effect on mTORC-1 and IκB kinase complex (Ikk-β). The present findings highlight the future pharmaceutical utilization of coriander extract as valuable source of phenolic compounds that can be used as antioxidant, anti-inflammatory, and neuroprotective agents against Pb-induced neurotoxicity.

The Biflavonoid Agathisflavone Regulates Microglial and Astrocytic Inflammatory Profiles via Glucocorticoid Receptor

Nuclear receptors such as glucocorticoid receptors (GRs) are transcription factors with prominent regulatory effects on neuroinflammation. Agathisflavone is a biflavonoid that demonstrates neurogenic, neuroprotective, anti-inflammatory, antioxidant, and pro-myelinogenic effects in vitro. This study investigated whether the control of glial reactivity by agathisflavone is mediated by GRs. Primary cultures of astrocytes and microglia were induced to neuroinflammation by lipopolysaccharides (LPSs) and exposed to agathisflavone or not in the presence or absence of mifepristone, a GR antagonist. The microglia morphology and reactivity were evaluated by immunofluorescence against calcium-binding ionized adapter (Iba-1) and CD68. The astrocyte morphology and reactivity were evaluated by immunofluorescence against glial fibrillary acidic protein (GFAP). The inflammatory profile was evaluated by RT-qPCR. Molecular docking was performed to characterize agathisflavone and GR interactions. Microglial branching was increased in response to agathisflavone, an effect that was inhibited by mifepristone. CD68 and GFAP expression was decreased by agathisflavone but not in the presence of mifepristone. Agathisflavone decreased the expression of the pro-inflammatory cytokine IL-1β and increased the expression of the regulatory cytokine IL-10. The increase in IL-10 mRNA was inhibited by the GR antagonist. The in silico analysis showed that agathisflavone binds to a pocket at the glucocorticoid receptor. These interactions were stronger than mifepristone, dexamethasone, and the agathisflavone monomer apigenin. These results indicate that the GR is involved in the regulatory effects of agathisflavone on microglia and astrocyte inflammation, contributing to the elucidation of the molecular mechanisms of agathisflavone's effects in the nervous system.

Much More than Nutrients: The Protective Effects of Nutraceuticals on the Blood-Brain Barrier in Diseases

The dysfunction of the blood-brain barrier (BBB) is well described in several diseases, and is considered a pathological factor in many neurological disorders. This review summarizes the most important groups of natural compounds, including alkaloids, flavonoids, anthocyanidines, carotenoids, lipids, and vitamins that were investigated for their potential protective effects on brain endothelium. The brain penetration of these compounds and their interaction with BBB efflux transporters and solute carriers are discussed. The cerebrovascular endothelium is considered a therapeutic target for natural compounds in diseases. In preclinical studies modeling systemic and central nervous system diseases, nutraceuticals exerted beneficial effects on the BBB. In vivo, they decreased BBB permeability, brain edema, astrocyte swelling, and morphological changes in the vessel structure and basal lamina. At the level of brain endothelial cells, nutraceuticals increased cell survival and decreased apoptosis. From the general endothelial functions, decreased angiogenesis and increased levels of vasodilating agents were demonstrated. From the BBB functions, elevated barrier integrity by tightened intercellular junctions, and increased expression and activity of BBB transporters, such as efflux pumps, solute carriers, and metabolic enzymes, were shown. Nutraceuticals enhanced the antioxidative defense and exerted anti-inflammatory effects at the BBB. The most important signaling changes mediating the increased cell survival and BBB stability were the activation of the WNT, PI3K-AKT, and NRF2 pathways, and inhibition of the MAPK, JNK, ERK, and NF-κB pathways. Nutraceuticals represent a valuable source of new potentially therapeutic molecules to treat brain diseases by protecting the BBB.

The Advancements of Marine Natural Products in the Treatment of Alzheimer's Disease: A Study Based on Cell and Animal Experiments

As life expectancy rises and the aging population grows, Alzheimer's disease (AD) has become a significant global health concern. AD is a complex neurodegenerative disorder with an unclear etiology. Current hypotheses primarily focus on β-amyloid (Aβ) aggregation, tau protein hyperphosphorylation, and neuroinflammation as key pathological processes. Given the limited efficacy of existing therapeutic strategies, there is an urgent need to explore novel treatment options. Marine natural products have garnered significant attention due to their unique chemical structures and diverse bioactivities, demonstrating potential for multi-target interventions in AD. This review systematically summarizes the roles of marine-derived compounds, including polysaccharides, carotenoids, and polyphenols, in modulating Aβ aggregation, mitigating tau protein pathology, and regulating gut-brain axis dysfunction. Furthermore, the challenges of current research are discussed, with an emphasis on improving blood-brain barrier permeability and optimizing drug delivery systems to facilitate clinical translation.

Role of AIM2 and cGAS-STING signaling in high fat high carbohydrate diet-induced gut dysbiosis associated neurodegeneration

AIMS

Gut dysbiosis modulates CNS complications and cognitive decline through the gut-brain axis. The study aims to investigate the molecular mechanisms involved in gut dysbiosis-associated cognitive changes and the potential effects of probiotics in high fat-high carbohydrate diet-induced gut dysbiosis-associated neurodegeneration.

MATERIALS AND METHODS

We used high fat, high-carbohydrate diet (HFHCD) and high-fat diet (HFD) to induce gut dysbiosis-associated neurodegeneration in C57BL/6 mice. IVIS imaging system and biochemical changes using ELISA measured intestinal inflammation. We used fecal samples for qPCR profiling of intestinal bacteria, and serum was used for inflammatory marker analysis using ELISA. Behavioral studies measured cognitive changes, while histopathology, immunohistochemistry, and western blot analysis of hippocampal samples measured protein changes.

KEY FINDINGS

The behavioral studies showed a significant decrease in cognitive function associated with gut dysbiosis in HFHCD and HFD animals. Gut dysbiosis was associated with intestinal inflammation and increased intestinal permeability, followed by systemic and neuroinflammatory changes. Molecular signaling studies showed the involvement of AIM2 inflammasome and cGAS-STING signaling pathways in neurodegeneration for HFHCD animals. Administration of probiotics restored the above processes and prevented gut dysbiosis-associated memory decline in mice.

SIGNIFICANCE

The study shows that alteration in microbial composition due to prolonged HFHCD could contribute to intestinal inflammation and increased intestinal permeability, facilitating the translocation of microbial toxins like LPS, leading to systemic inflammation, which eventually leads to neuroinflammation and neurodegeneration.

Malícia honey (Mimosa quadrivalvis L.) produced by the jandaíra bee (Melipona subnitida D.) shows antioxidant activity via phenolic compound action in obese rats

Background and aims

Obesity is a disease associated with increased oxidative stress in humans and animals, and consumption of antioxidant compounds such as polyphenols can minimise it. These compounds are abundant in malícia (Mimosa quadrivalvis L.) honey produced by stingless bees. This study aimed to evaluate whether administration of Mimosa quadrivalvis L. honey to obese rats could reduce oxidative stress in vital organs through phenolic compound action.

Methods

Wistar rats (228 ± 14.69 g) were randomly divided into two groups: a healthy group (HG, n = 20) fed a control diet and an obese group (OG, n = 20) fed a cafeteria diet for the initial 8 weeks. After this period, these groups were again randomised into four subgroups: healthy (HG, n = 10), obese (OG, n = 10), healthy with malícia honey administration (1,000 mg/kg; HGH, n = 10), and obese with malícia honey administration (1,000 mg/kg; OGH, n = 10) for the final 8 weeks fed the previously mentioned diets. The rats were euthanised at the end of the experiment to collect brain, gut, kidney, and liver tissues to evaluate parameters related to oxidative stress and phenolic profile.

Results

The administration of malícia honey reduced energy intake and weight gain in the OGH in comparison to the OG. Total antioxidant capacity increased in the brain, liver, and gut in both groups treated with honey compared to respective controls. Lipid peroxidation decreased in the brain, gut, and kidney of the OGH. Both treated groups showed elevated phenolic compound deposition, including catechin, procyanidins, and flavonoids, across all organs. Specifically, the brain in the OGH showed greater procyanidin B2 and gallic acid deposition; the liver showed increased procyanidin B1 and B2, epicatechin, and myricetin concentrations; the gut showed higher procyanidin B2 and kaempferol 3-glucoside concentrations; and the kidneys had increased catechin, procyanidin B1 and B2, and gallic acid deposition compared to the OG.

Conclusion

Histologically, the OGH displayed reduced neuronal damage and prevention of hepatic steatosis induced by the cafeteria diet. Malícia honey effectively reduced oxidative stress via modulation of phenolic compounds in the brain, gut, kidney, and liver of cafeteria diet-induced obese rats.

Short-term caloric restriction or resveratrol supplementation alters large-scale brain network connectivity in male and female rats

Introduction

Dietary interventions such as caloric restriction (CR) exert positive effects on brain health. Unfortunately, poor compliance hinders the success of this approach. A proposed alternative is resveratrol (Rsv), a CR-mimetic known to promote brain health. Direct comparison between the effects of Rsv and CR on brain health is lacking, with limited knowledge on their sex-specific effects. Therefore, we aimed to compare and unravel the sex-specific impact of these dietary interventions on spontaneous brain activity.

Methods

Here, we used resting-state fMRI to investigate functional connectivity (FC) changes in five prominent resting-state brain networks (RSNs) in healthy 4 month old male and female F344 rats supplemented to either 40% CR or daily Rsv supplementation (10 mg/kg, oral) for the duration of 1 month.

Results

Our results demonstrated a decreased body weight (BW) in CR rats, as well as an increase in body weight in male Rsv supplemented rats, compared to female Rsv supplemented rats, whereas this difference between sexes was not observed in the control or CR groups. Furthermore, we found that both CR or Rsv supplementation induce a female-specific decrease of FC between the subcortical network and hippocampal network, and between the subcortical network and lateral cortical network. Moreover, Rsv supplementation lowered FC within the hippocampal network and between the hippocampal and the default mode like network, the lateral cortical network and the sensory network-an effect not observed for the CR rats.

Discussion

Our findings reveal that both CR and Rsv induce a similar female-specific decrease of FC in RSNs associated with memory and emotion, all the while CR and Rsv induce dissimilar changes in body weight and other within- and between-RSN FC measures. Altogether, this study provides insight into the effects and comparability of short-term CR and Rsv supplementation on brain connectivity within- and between-RSNs in both male and female F344 rats, providing a FC reference for future research of dietary effects.

The Flavonoid Agathisflavone Attenuates Glia Activation After Mechanical Injury of Cortical Tissue and Negatively Regulates Both NRLP3 and IL-1β Expression

Traumatic brain injury (TBI) has a complex and multifactorial pathology and is a major cause of death and disability for humans. Immediately after TBI, astrocytes and microglia react with complex morphological and functional changes known as reactive gliosis to form a glial scar in the area immediately adjacent to the lesion, which is the major barrier to neuronal regeneration. The flavonoid agathisflavone (bis-apigenin), present in Poincianella pyramidalis leaves, has been shown to have neuroprotective, neurogenic, and anti-inflammatory effects, demonstrated in vitro models of glutamate-induced toxicity, neuroinflammation, and demyelination. In this study, we evaluated the effect and mechanisms of agathisflavone in neuronal integrity and in the modulation of gliosis in an ex vivo model of TBI. For this, microdissections from the encephalon of Wistar rats (P6-8) were prepared and subjected to mechanical injury (MI) and treated or not with daily agathisflavone (5 μM) for 3 days. Astrocyte reactivity was investigated by measuring mRNA and expression of GFAP protein in the lesioned area by immunofluorescence and Western blot. The proportion of microglia was determined by immunofluorescence for Iba-1; mRNA expression for inflammasome NRPL3 and interleukin-1 beta (IL-1β) was determined by RT-qPCR. It was observed that lesions in the cortical tissue induced astrocytes overexpressing GFAP in the typical glial scar formed and that agathisflavone modulated GFAP expression at the transcriptional and post-transcriptional levels, which was associated with a reduction of the glial scar. MI induced an increase in the proportion of microglia (Iba-1+), which was not observed in agathisflavone-treated cultures. Moreover, the flavonoid modulated negatively both the NRLP3 and IL-1β mRNA expression that was increased in the lesioned area of the tissue. These findings support the regulatory properties of agathisflavone in the control of the inflammatory response in glial cells, which can impact neuroprotection and should be considered for future studies for TB and other pathological conditions of the central nervous system.

From the gut to the brain: the long journey of phenolic compounds with neurocognitive effects

The human gut microbiota is a complex community of micro-organisms that play a crucial role in maintaining overall health. Recent research has shown that gut microbes also have a profound impact on brain function and cognition, leading to the concept of the gut-brain axis. One way in which the gut microbiota can influence the brain is through the bioconversion of polyphenols to other bioactive molecules. Phenolic compounds are a group of natural plant metabolites widely available in the human diet, which have anti-inflammatory and other positive effects on health. Recent studies have also suggested that some gut microbiota-derived phenolic metabolites may have neurocognitive effects, such as improving memory and cognitive function. The specific mechanisms involved are still being studied, but it is believed that phenolic metabolites may modulate neurotransmitter signaling, reduce inflammation, and enhance neural plasticity. Therefore, to exert a protective effect on neurocognition, dietary polyphenols or their metabolites must reach the brain, or act indirectly by producing an increase in bioactive molecules such as neurotransmitters. Once ingested, phenolic compounds are subjected to various processes (eg, metabolization by gut microbiota, absorption, distribution) before they cross the blood-brain barrier, perhaps the most challenging stage of their trajectory. Understanding the role of phenolic compounds in the gut-brain axis has important implications for the development of new therapeutic strategies for neurological and psychiatric disorders. By targeting the gut microbiota and its production of phenolic metabolites, it may be possible to improve brain function and prevent cognitive decline. In this article, the current state of knowledge on the endogenous generation of phenolic metabolites by the gut microbiota and how these compounds can reach the brain and exert neurocognitive effects was reviewed.

Curcumin attenuates neuroinflammatory damage induced by LPS: Implications for the role of S100B

Inflammation is a common feature of neurological disorders that alters cell function in microglia and astrocytes as well as other neuronal cell types. Astrocytes modulate blood flow, regulate glutamate metabolism, and exert antioxidant protection. When responding to inflammatory damage, astrocytes enhance immune cell infiltration and amplify inflammatory responses via the upregulation of cytokine production. Several molecules have been proposed to attenuate neuroinflammation and control neurological diseases. Curcumin gained attention due to its capacity to cross the blood-brain barrier and its well-described anti-inflammatory and antioxidant activities. Our study aimed to understand if oral curcumin administration could protect against central nervous system inflammatory damage induced by intracerebroventricular injection of LPS while focusing on astrocyte function. Despite its poor bioavailability, we found that curcumin reaches the central nervous system, prevents the locomotory damage caused by LPS, and reduces inflammatory signaling via IL-1β and COX-2. Furthermore, we observed that curcumin was protective against LPS-induced S100B secretion in the cerebrospinal fluid and GSH reduction in the hippocampal tissue. However, curcumin could not protect the animals from anhedonia, assessed by the sucrose preference test, and weight loss induced by LPS. Our results indicate that oral curcumin administration exerts a protective anti-inflammatory action in the central nervous system, attenuating the sickness behavior induced by ICV LPS. This work demonstrates that curcumin has an important modulative effect on astrocytes, thus suggesting that astrocytes are critical to the anti-inflammatory effects of curcumin.

The Role of Gut Microbiome in Irritable Bowel Syndrome: Implications for Clinical Therapeutics

Irritable bowel syndrome (IBS) is a functional gastrointestinal disorder (FGID) characterized by chronic or recurrent gastrointestinal symptoms without organic changes, and it is also a common disorder of gut-brain interaction (DGBIs).. The symptoms of IBS not only affect the quality of life for individual patients but also place a significant burden on global healthcare systems. The lack of established and universally applicable biomarkers for IBS, along with the substantial variability in symptoms and progression, presents challenges in developing effective clinical treatments. In recent years, preclinical and clinical studies have linked the pathogenesis of IBS to alterations in the composition and function of the intestinal microbiota. Within the complex microbial community of the gut, intricate metabolic and spatial interactions occur among its members and between microbes and their hosts. Amid the multifaceted pathophysiology of IBS, the role of intestinal microenvironment factors in symptom development has become more apparent. This review aims to delve into the changes in the composition and structure of the gut microbiome in individuals with IBS. It explores how diet-mediated alterations in intestinal microbes and their byproducts play a role in regulating the pathogenesis of IBS by influencing the "brain-gut" axis, intestinal barrier function, immune responses, and more. By doing so, this review seeks to lay a theoretical foundation for advancing the development of clinical therapeutics for IBS.

Dietary Strategies to Mitigate Alzheimer's Disease: Insights into Antioxidant Vitamin Intake and Supplementation with Microbiota-Gut-Brain Axis Cross-Talk

Alzheimer's disease (AD), which is characterized by deterioration in cognitive function and neuronal death, is the most prevalent age-related progressive neurodegenerative disease. Clinical and experimental research has revealed that gut microbiota dysbiosis may be present in AD patients. The changed gut microbiota affects brain function and behavior through several mechanisms, including tau phosphorylation and increased amyloid deposits, neuroinflammation, metabolic abnormalities, and persistent oxidative stress. The lack of effective treatments to halt or reverse the progression of this disease has prompted a search for non-pharmaceutical tools. Modulation of the gut microbiota may be a promising strategy in this regard. This review aims to determine whether specific dietary interventions, particularly antioxidant vitamins, either obtained from the diet or as supplements, may support the formation of beneficial microbiota in order to prevent AD development by contributing to the systemic reduction of chronic inflammation or by acting locally in the gut. Understanding their roles would be beneficial as it may have the potential to be used as a future therapy option for AD patients.

Bioactive compounds regulate appetite through the melanocortin system: a review

Obesity, a significant health crisis, arises from an imbalance between energy intake and expenditure. Enhancing appetite regulation has garnered substantial attention from researchers as a novel and effective strategy for weight management. The melanocortin system, situated in the hypothalamus, is recognized as a critical node in the regulation of appetite. It integrates long-term and short-term hormone signals from the periphery as well as nutrients, forming a complex network of interacting feedback mechanisms with the gut-brain axis, significantly contributing to the regulation of energy homeostasis. Appetite regulation by bioactive compounds has been a focus of intensive research due to their favorable safety profiles and easy accessibility. These bioactive compounds, derived from a variety of plant and animal sources, modulate the melanocortin system and influence appetite and energy homeostasis through multiple pathways: central nervous system, peripheral hormones, and intestinal microbiota. Here, we review the anatomy, function, and receptors of the melanocortin system, outline the long-term and short-term regulatory hormones that act on the melanocortin system, and discuss the bioactive compounds and their mechanisms of action that exert a regulatory effect on appetite by targeting the melanocortin system. This review contributes to a better understanding of how bioactive compounds regulate appetite via the melanocortin system, thereby providing nutritional references for citizens' dietary preferences.

mRNA delivery enabled by metal-organic nanoparticles

mRNA therapeutics are set to revolutionize disease prevention and treatment, inspiring the development of platforms for safe and effective mRNA delivery. However, current mRNA delivery platforms face some challenges, including limited organ tropism for nonvaccine applications and inflammation induced by cationic nanoparticle components. Herein, we address these challenges through a versatile, noncationic nanoparticle platform whereby mRNA is assembled into a poly(ethylene glycol)-polyphenol network stabilized by metal ions. Screening a range of components and relative compositional ratios affords a library of stable, noncationic, and highly biocompatible metal-organic nanoparticles with robust mRNA transfection in vitro and in mice. Intravenous administration of the lead mRNA-containing metal-organic nanoparticles enables predominant protein expression and gene editing in the brain, liver, and kidney, while organ tropism is tuned by varying nanoparticle composition. This study opens an avenue for realizing metal-organic nanoparticle-enabled mRNA delivery, offering a modular approach to assembling mRNA therapeutics for health applications.

Microalgal Phenolics: Systematic Review with a Focus on Methodological Assessment and Meta-Analysis

A critical review and analysis of the literature relevant to the phenolic content of eucaryotic microalgae was performed. Several issues were identified and discussed. In summary, the main problems with the reporting on the phenolic content of microalgae are the following: (1) despite its usefulness in the determination of phenolic content in plant samples, the Folin-Ciocalteu assay is non-suitable for microalgal research due to the high presence of interfering compounds in microalgal extracts such as chlorophyll and its derivatives in organic extracts and free aromatic amino acids or nucleotides in aqueous extracts; (2) while there is chromatographic evidence for the presence of simple phenolic acids in most microalgal clades, the lack of critical enzymes of phenolic biosynthesis in most microalgae, as well as the high variability of phenolic profiles even in the same genus, require more extensive research before conclusions are drawn; (3) the accumulation and metabolism of external phenolics by microalgae has been almost universally neglected in studies focusing on the phenolic content of microalgae, even when natural seawater or complex organic media are used in the cultivation process. Despite these issues, the literature focusing on the bioremediation of waste streams rich in phenolics through microalgae demonstrates the ability of those organisms to adsorb, internalize, and in many cases oxidize or transform a wide range of phenolic compounds, even at very high concentrations. Simple phenolics found in waste streams, such as olive mill waste, have been shown to enhance the antioxidant activity and various bioactivities of microalgal extracts, while complex biotransformation products of phenolics have also been characterized. In conclusion, the de novo biosynthesis of phenolic compounds via eucaryotic microalgae requires further investigation with better designed experiments and suitable analytical methods, while the response of microalgae to phenolic compounds in their growth medium is of great practical interest, both in terms of waste treatment and for the production of functional foods, cosmetics, and pharmaceuticals.

Unlocking the potential of low-molecular-weight (Poly)phenol metabolites: Protectors at the blood-brain barrier frontier

Neurodegenerative diseases (NDDs) are an increasing group of chronic and progressive neurological disorders that ultimately lead to neuronal cell failure and death. Despite all efforts throughout decades, their burden on individuals and society still casts one of the most massive socioeconomic problems worldwide. The neuronal failure observed in NDDs results from an intricacy of events, mirroring disease complexity, ranging from protein aggregation, oxidative stress, (neuro)inflammation, and even blood-brain barrier (BBB) dysfunction, ultimately leading to cognitive and motor symptoms in patients. As a result of such complex pathobiology, to date, there are still no effective treatments to treat/halt NDDs progression. Fortunately, interest in the bioavailable low molecular weight (LMW) phenolic metabolites derived from the metabolism of dietary (poly)phenols has been rising due to their multitargeted potential in attenuating multiple NDDs hallmarks. Even if not highly BBB permeant, their relatively high concentrations in the bloodstream arising from the intake of (poly)phenol-rich diets make them ideal candidates to act within the vasculature and particularly at the level of BBB. In this review, we highlight the most recent - though still scarce - studies demonstrating LMW phenolic metabolites' ability to modulate BBB homeostasis, including the improvement of tight and adherens junctional proteins, as well as their power to decrease pro-inflammatory cytokine secretion and oxidative stress levels in vitro and in vivo. Specific BBB-permeant LMW phenolic metabolites, such as simple phenolic sulfates, have been emerging as strong BBB properties boosters, pleiotropic compounds capable of improving cell fitness under oxidative and pro-inflammatory conditions. Nevertheless, further studies should be pursued to obtain a holistic overview of the promising role of LMW phenolic metabolites in NDDs prevention and management to fully harness their true therapeutic potential.

Potential of dietary polyphenols for protection from age-related decline and neurodegeneration: a role for gut microbiota?

Many epidemiological studies have shown the beneficial effects of a largely plant-based diet, and the strong association between the consumption of a Mediterranean-type diet with healthy aging including a lower risk of cognitive decline. The Mediterranean diet is characterized by a high intake of olive oil, fruits and vegetables and is rich in dietary fiber and polyphenols - both of which have been postulated to act as important mediators of these benefits. Polyphenols are large molecules produced by plants to protect them from environmental threats and injury. When ingested by humans, as little as 5% of these molecules are absorbed in the small intestine with the majority metabolized by the gut microbiota into absorbable simple phenolic compounds. Flavan-3-ols, a type of flavonoid, contained in grapes, berries, pome fruits, tea, and cocoa have been associated with many beneficial effects on several risk factors for cardiovascular disease, cognitive function and brain regions involved in memory formation. Both preclinical and clinical studies suggest that these brain and heart benefits can be attributed to endothelial vascular effects and anti-inflammatory properties among others. More recently the gut microbiota has emerged as a potential modulator of the aging brain and intriguingly polyphenols have been shown to alter microbiota composition and be metabolized by different microbial species. However, there is a need for well controlled studies in large populations to identify predictors of response, particularly given the vast inter-individual variation of human gut microbiota.

Gut microbiota: the indispensable player in neurodegenerative diseases

As one of the most urgent social and health problems in the world, neurodegenerative diseases have always been of interest to researchers. However, the pathological mechanisms and therapeutic approaches are not achieved. In addition to the established roles of oxidative stress, inflammation and immune response, changes of gut microbiota are also closely related to the pathogenesis of neurodegenerative diseases. Gut microbiota is the central player of the gut-brain axis, the dynamic bidirectional communication pathway between gut microbiota and central nervous system, and emerging insights have confirmed its indispensability in the development of neurodegenerative diseases. In this review, we discuss the complex relationship between gut microbiota and the central nervous system from the perspective of the gut-brain axis; review the mechanism of microbiota for the modulation different neurodegenerative diseases and discuss how different dietary patterns affect neurodegenerative diseases via gut microbiota; and prospect the employment of gut microbiota in the therapeutic approach to those diseases. © 2024 Society of Chemical Industry.

Deciphering the microbial map and its implications in the therapeutics of neurodegenerative disorder

Every facet of biological anthropology, including development, ageing, diseases, and even health maintenance, is influenced by gut microbiota's significant genetic and metabolic capabilities. With current advancements in sequencing technology and with new culture-independent approaches, researchers can surpass older correlative studies and develop mechanism-based studies on microbiome-host interactions. The microbiota-gut-brain axis (MGBA) regulates glial functioning, making it a possible target for the improvement of development and advancement of treatments for neurodegenerative diseases (NDDs). The gut-brain axis (GBA) is accountable for the reciprocal communication between the gastrointestinal and central nervous system, which plays an essential role in the regulation of physiological processes like controlling hunger, metabolism, and various gastrointestinal functions. Lately, studies have discovered the function of the gut microbiome for brain health-different microbiota through different pathways such as immunological, neurological and metabolic pathways. Additionally, we review the involvement of the neurotransmitters and the gut hormones related to gut microbiota. We also explore the MGBA in neurodegenerative disorders by focusing on metabolites. Further, targeting the blood-brain barrier (BBB), intestinal barrier, meninges, and peripheral immune system is investigated. Lastly, we discuss the therapeutics approach and evaluate the pre-clinical and clinical trial data regarding using prebiotics, probiotics, paraprobiotics, fecal microbiota transplantation, personalised medicine, and natural food bioactive in NDDs. A comprehensive study of the GBA will felicitate the creation of efficient therapeutic approaches for treating different NDDs.

Pterostilbene Ameliorates Cognitive Impairment in Polycystic Ovary Syndrome Rat Model through Improving Insulin Resistance via the IRS-1/PI3K/Akt/GSK-3β Pathway: A Comparative Study with Metformin

Polycystic ovary syndrome (PCOS) is an intricate endocrine disorder that targets millions of women globally. Recent research has drawn attention to its association with cognitive impairment and Alzheimer's disease (AD) risk, yet the exact mechanism remains elusive. This study aimed to explore the potential role of PCOS-associated insulin resistance (IR) and inflammation in linking PCOS to AD pathogenesis. It additionally investigated the therapeutic merits of pterostilbene (PTS) in ameliorating PCOS and associated cognitive deficits in comparison to metformin (MET). Rats were divided into five groups; vehicle group, PTS group [30 mg/kg, per os (p.o.) for 13 days], and the remaining three groups received letrozole (1 mg/kg, p.o. for 21 days) to represent the PCOS, PCOS + MET (300 mg/kg, p.o. for 13 days), and PCOS + PTS groups, respectively. Behavioral tests were conducted, along with a histopathological investigation of brains and ovaries. Assessment of serum hormonal profile and hippocampal IRS-1/PI3K/AKT/GSK-3β insulin signaling pathway components were performed. PTS rats exhibited improved insulin sensitivity and hormonal profile, besides enhanced neurobehavioral tests performance and histopathological findings. These effects may be attributed to modulation of the IRS-1/PI3K/AKT/GSK-3β pathway, reducing GSK-3β activity, and mitigating Tau hyperphosphorylation and Aβ accumulation in the brain. Likewise, PTS attenuated nuclear factor kappa B-mediated inflammation and reversed AChE elevation, suggesting multifaceted neuroprotective effects. Comparatively, PTS showed outcomes similar to those of MET in most parameters. The obtained findings validated that dysregulated insulin signaling in PCOS rats detrimentally affects cognitive function, which is halted by PTS, unveiling the potential of PTS as a novel therapy for PCOS and related cognitive deficits.

Citrus Flavanone Effects on the Nrf2-Keap1/GSK3/NF-κB/NLRP3 Regulation and Corticotroph-Stress Hormone Loop in the Old Pituitary

Oxidative stress and inflammation are significant causes of aging. At the same time, citrus flavanones, naringenin (NAR), and hesperetin (HES) are bioactives with proven antioxidant and anti-inflammatory properties. Nevertheless, there are still no data about flavanone's influence and its potential effects on the healthy aging process and improving pituitary functioning. Thus, using qPCR, immunoblot, histological techniques, and biochemical assays, our study aimed to elucidate how citrus flavanones (15 mg/kg b.m. per os) affect antioxidant defense, inflammation, and stress hormone output in the old rat model. Our results showed that HES restores the redox environment in the pituitary by down-regulating the nuclear factor erythroid 2-related factor 2 (Nrf2) protein while increasing kelch-like ECH-associated protein 1 (Keap1), thioredoxin reductase (TrxR1), and superoxide dismutase 2 (SOD2) protein expression. Immunofluorescent analysis confirmed Nrf2 and Keap1 down- and up-regulation, respectively. Supplementation with NAR increased Keap1, Trxr1, glutathione peroxidase (Gpx), and glutathione reductase (Gr) mRNA expression. Decreased oxidative stress aligned with NLRP3 decrement after both flavanones and glycogen synthase kinase-3 (GSK3) only after HES. The signal intensity of adrenocorticotropic hormone (ACTH) cells did not change, while corticosterone levels in serum decreased after both flavanones. HES showed higher potential than NAR in affecting a redox environment without increasing the inflammatory response, while a decrease in corticosterone level has a solid link to longevity. Our findings suggest that HES could improve and facilitate redox and inflammatory dysregulation in the rat's old pituitary.

Unveiling the Therapeutic Potential of Kelulut (Stingless Bee) Honey in Alzheimer's Disease: Findings from a Rat Model Study

Alzheimer's disease (AD) poses a major worldwide health challenge because of its profound impact on cognitive abilities and overall well-being. Despite extensive research and numerous clinical trials, therapeutic options remain limited. Our study aimed to investigate the potential of Kelulut honey (KH) as a novel therapeutic agent for addressing the multifactorial pathology of AD. We tried to evaluate the disease-attenuating and neuroprotective potential of KH in the intrahippocampally induced AD rat model by utilizing histochemistry and enzyme-linked immunosorbent assay (ELISA) studies. A total of 26 male Sprague Dawley rats weighing ~280-380 g were randomly divided into three groups: Control, AD-induced (Aβ), and AD-induced and treated with KH (Aβ+KH). The latter two groups underwent stereotaxic surgery, where 6.25 µg of amyloid β1-42 peptides were injected intrahippocampally. One-week post-surgery, KH was administered to the treatment group at a dose of 1 g/kg body weight for a period of four weeks, after which the rats went through behavior tests. After completion of behavior analysis, the rats were sacrificed, and the brains were processed for histochemistry and ELISA studies. The open field test analysis demonstrated that KH improved the locomotion of Aβ+KH compared to Aβ (p = 0.0013). In comparison, the Morris water maze did not show any nootropic effects on cognition with a paradoxical increase in time spent in the target quadrant by the Aβ group (p = 0.029). Histochemical staining showed markedly increased Congo-red-stained amyloid plaques, which were significantly reduced in dentate gyrus of Aβ+KH compared to Aβ (p < 0.05). Moreover, significantly higher apoptosis was seen in the Aβ group compared to Aβ+KH (p < 0.01) and control groups (p < 0.001). Furthermore, the ELISA studies deduced more phosphorylated tau in the diseased group compared to Aβ+KH (p = 0.038) and controls (p = 0.016). These findings suggest that KH consumption for twenty-eight days has the potential to attenuate the pathological burden of disease while exerting neuroprotective effects in rodent models of AD.

Circulating low-molecular-weight (poly)phenol metabolites in the brain: unveiling in vitro and in vivo blood-brain barrier transport

Circulating metabolites resulting from colonic metabolism of dietary (poly)phenols are highly abundant in the bloodstream, though still marginally explored, particularly concerning their brain accessibility. Our goal is to disclose (poly)phenol metabolites' blood-brain barrier (BBB) transport, in vivo and in vitro, as well as their role at BBB level. For three selected metabolites, benzene-1,2-diol-3-sulfate/benzene-1,3-diol-2-sulfate (pyrogallol-sulfate - Pyr-sulf), benzene-1,3-diol-6-sulfate (phloroglucinol-sulfate - Phlo-sulf), and phenol-3-sulfate (resorcinol-sulfate - Res-sulf), BBB transport was assessed in human brain microvascular endothelial cells (HBMEC). Their potential in modulating in vitro BBB properties at circulating concentrations was also studied. Metabolites' fate towards the brain, liver, kidney, urine, and blood was disclosed in Wistar rats upon injection. Transport kinetics in HBMEC highlighted different BBB permeability rates, where Pyr-sulf emerged as the most in vitro BBB permeable metabolite. Pyr-sulf was also the most potent regarding BBB properties improvement, namely increased beta(β)-catenin membrane expression and reduction of zonula occludens-1 membrane gaps. Whereas no differences were observed for transferrin, increased expression of caveolin-1 upon Pyr-sulf and Res-sulf treatments was found. Pyr-sulf was also capable of modulating gene and protein expression of some solute carrier transporters. Notably, each of the injected metabolites exhibited a unique tissue distribution in vivo, with the remarkable ability to almost immediately reach the brain.

Beneficial Effects of Manilkara zapota-Derived Bioactive Compounds in the Epigenetic Program of Neurodevelopment

Gestational diet has a long-dated effect not only on the disease risk in offspring but also on the occurrence of future neurological diseases. During ontogeny, changes in the epigenetic state that shape morphological and functional differentiation of several brain areas can affect embryonic fetal development. Many epigenetic mechanisms such as DNA methylation and hydroxymethylation, histone modifications, chromatin remodeling, and non-coding RNAs control brain gene expression, both in the course of neurodevelopment and in adult brain cognitive functions. Epigenetic alterations have been linked to neuro-evolutionary disorders with intellectual disability, plasticity, and memory and synaptic learning disorders. Epigenetic processes act specifically, affecting different regions based on the accessibility of chromatin and cell-specific states, facilitating the establishment of lost balance. Recent insights have underscored the interplay between epigenetic enzymes active during embryonic development and the presence of bioactive compounds, such as vitamins and polyphenols. The fruit of Manilkara zapota contains a rich array of these bioactive compounds, which are renowned for their beneficial properties for health. In this review, we delve into the action of each bioactive micronutrient found in Manilkara zapota, elucidating their roles in those epigenetic mechanisms crucial for neuronal development and programming. Through a comprehensive understanding of these interactions, we aim to shed light on potential avenues for harnessing dietary interventions to promote optimal neurodevelopment and mitigate the risk of neurological disorders.

Coffee polyphenols ameliorate early-life stress-induced cognitive deficits in male mice

Stress exposure during the sensitive period of early development has been shown to program the brain and increases the risk to develop cognitive deficits later in life. We have shown earlier that early-life stress (ES) leads to cognitive decline at an adult age, associated with changes in adult hippocampal neurogenesis and neuroinflammation. In particular, ES has been shown to affect neurogenesis rate and the survival of newborn cells later in life as well as microglia, modulating their response to immune or metabolic challenges later in life. Both of these processes possibly contribute to the ES-induced cognitive deficits. Emerging evidence by us and others indicates that early nutritional interventions can protect against these ES-induced effects through nutritional programming. Based on human metabolomics studies, we identified various coffee-related metabolites to be part of a protective molecular signature against cognitive decline in humans. Caffeic and chlorogenic acids are coffee-polyphenols and have been described to have potent anti-oxidant and anti-inflammatory actions. Therefore, we here aimed to test whether supplementing caffeic and chlorogenic acids to the early diet could also protect against ES-induced cognitive deficits. We induced ES via the limited nesting and bedding paradigm in mice from postnatal(P) day 2-9. On P2, mice received a diet to which 0.02% chlorogenic acid (5-O-caffeoylquinic acid) + 0.02% caffeic acid (3',4'-dihydroxycinnamic acid) were added, or a control diet up until P42. At 4 months of age, all mice were subjected to a behavioral test battery and their brains were stained for markers for microglia and neurogenesis. We found that coffee polyphenols supplemented early in life protected against ES-induced cognitive deficits, potentially this is mediated by the survival of neurons or microglia, but possibly other mechanisms not studied here are mediating the effects. This study provides additional support for the potential of early nutritional interventions and highlights polyphenols as nutrients that can protect against cognitive decline, in particular for vulnerable populations exposed to ES.

Effectiveness of Flavonoid-Rich Diet in Alleviating Symptoms of Neurodegenerative Diseases

Over the past decades, there has been a significant increase in the burden of neurological diseases, including neurodegenerative disorders, on a global scale. This is linked to a widespread demographic trend in which developed societies are aging, leading to an increased proportion of elderly individuals and, concurrently, an increase in the number of those afflicted, posing one of the main public health challenges for the coming decades. The complex pathomechanisms of neurodegenerative diseases and resulting varied symptoms, which differ depending on the disease, environment, and lifestyle of the patients, make searching for therapies for this group of disorders a formidable challenge. Currently, most neurodegenerative diseases are considered incurable. An important aspect in the fight against and prevention of neurodegenerative diseases may be broadly understood lifestyle choices, and more specifically, what we will focus on in this review, a diet. One proposal that may help in the fight against the spread of neurodegenerative diseases is a diet rich in flavonoids. Flavonoids are compounds widely found in products considered healthy, such as fruits, vegetables, and herbs. Many studies indicated not only the neuroprotective effects of these compounds but also their ability to reverse changes occurring during the progression of diseases such as Alzheimer's, Parkinson's and amyotrophic lateral sclerosis. Here, we present the main groups of flavonoids, discussing their characteristics and mechanisms of action. The most widely described mechanisms point to neuroprotective functions due to strong antioxidant and anti-inflammatory effects, accompanied with their ability to penetrate the blood-brain barrier, as well as the ability to inhibit the formation of protein aggregates. The latter feature, together with promoting removal of the aggregates is especially important in neurodegenerative diseases. We discuss a therapeutic potential of selected flavonoids in the fight against neurodegenerative diseases, based on in vitro studies, and their impact when included in the diet of animals (laboratory research) and humans (population studies). Thus, this review summarizes flavonoids' actions and impacts on neurodegenerative diseases. Therapeutic use of these compounds in the future is potentially possible but depends on overcoming key challenges such as low bioavailability, determining the therapeutic dose, and defining what a flavonoid-rich diet is and determining its potential negative effects. This review also suggests further research directions to address these challenges.

Current Aspects of Selected Factors to Modulate Brain Health and Sports Performance in Athletes

This review offers a comprehensive evaluation of current aspects related to nutritional strategies, brain modulation, and muscle recovery, focusing on their applications and the underlying mechanisms of physiological adaptation for promoting a healthy brain, not only in athletes but also for recreationally active and inactive individuals. We propose that applying the rule, among others, of good sleep, regular exercise, and a properly balanced diet, defined as "SPARKS", will have a beneficial effect on the function and regeneration processes of the gut-brain-muscle axis. However, adopting the formula, among others, of poor sleep, stress, overtraining, and dysbiosis, defined as "SMOULDER", will have a detrimental impact on the function of this axis and consequently on human health as well as on athletes. Understanding these dynamics is crucial for optimizing brain health and cognitive function. This review highlights the significance of these factors for overall well-being, suggesting that adopting the "SPARKS" approach may benefit not only athletes but also older adults and individuals with health conditions.

Exploring and disentangling the production of potentially bioactive phenolic catabolites from dietary (poly)phenols, phenylalanine, tyrosine and catecholamines

Following ingestion of fruits, vegetables and derived products, (poly)phenols that are not absorbed in the upper gastrointestinal tract pass to the colon, where they undergo microbiota-mediated ring fission resulting in the production of a diversity of low molecular weight phenolic catabolites, which appear in the circulatory system and are excreted in urine along with their phase II metabolites. There is increasing interest in these catabolites because of their potential bioactivity and their use as biomarkers of (poly)phenol intake. Investigating the fate of dietary (poly)phenolics in the colon has become confounded as a result of the recent realisation that many of the phenolics appearing in biofluids can also be derived from the aromatic amino acids, l-phenylalanine and l-tyrosine, and to a lesser extent catecholamines, in reactions that can be catalysed by both colonic microbiota and endogenous mammalian enzymes. The available evidence, albeit currently rather limited, indicates that substantial amounts of phenolic catabolites originate from phenylalanine and tyrosine, while somewhat smaller quantities are produced from dietary (poly)phenols. This review outlines information on this topic and assesses procedures that can be used to help distinguish between phenolics originating from dietary (poly)phenols, the two aromatic amino acids and catecholamines.

Mechanistic insights into the potential role of dietary polyphenols and their nanoformulation in the management of Alzheimer's disease

Alzheimer's disease (AD) is a very common neurodegenerative disorder associated with memory loss and a progressive decline in cognitive activity. The two major pathophysiological factors responsible for AD are amyloid plaques (comprising amyloid-beta aggregates) and neurofibrillary tangles (consisting of hyperphosphorylated tau protein). Polyphenols, a class of naturally occurring compounds, are immensely beneficial for the treatment or management of various disorders and illnesses. Naturally occurring sources of polyphenols include plants and plant-based foods, such as fruits, herbs, tea, vegetables, coffee, red wine, and dark chocolate. Polyphenols have unique properties, such as being the major source of anti-oxidants and possessing anti-aging and anti-cancerous properties. Currently, dietary polyphenols have become a potential therapeutic approach for the management of AD, depending on various research findings. Dietary polyphenols can be an effective strategy to tackle multifactorial events that occur with AD. For instance, naturally occurring polyphenols have been reported to exhibit neuroprotection by modulating the Aβ biogenesis pathway in AD. Many nanoformulations have been established to enhance the bioavailability of polyphenols, with nanonization being the most promising. This review comprehensively provides mechanistic insights into the neuroprotective potential of dietary polyphenols in treating AD. It also reviews the usability of dietary polyphenol as nanoformulation for AD treatment.

Potential of Natural Phenolic Compounds against Doxorubicin-Induced Chemobrain: Biological and Molecular Mechanisms Involved

Chemotherapy-induced cognitive impairment or "chemobrain" is a prevalent long-term complication of chemotherapy and one of the more devastating. Most of the studies performed so far to identify the cognitive dysfunctions induced by antineoplastic chemotherapies have been focused on treatment with anthracyclines, frequently administered to breast cancer patients, a population that, after treatment, shows a high possibility of long survival and, consequently, of chemobrain development. In the last few years, different possible strategies have been explored to prevent or reduce chemobrain induced by the anthracycline doxorubicin (DOX), known to promote oxidative stress and inflammation, which have been strongly implicated in the development of this brain dysfunction. Here, we have critically analyzed the results of the preclinical studies from the last few years that have evaluated the potential of phenolic compounds (PheCs), a large class of natural products able to exert powerful antioxidant and anti-inflammatory activities, in inhibiting DOX-induced chemobrain. Several PheCs belonging to different classes have been shown to be able to revert DOX-induced brain morphological damages and deficits associated with learning, memory, and exploratory behavior. We have analyzed the biological and molecular mechanisms implicated and suggested possible future perspectives in this research area.

Neuroprotective Effect of Sterculia setigera Leaves Hydroethanolic Extract

Plants are a valuable source of information for pharmacological research and new drug discovery. The present study aimed to evaluate the neuroprotective potential of the leaves of the medicinal plant Sterculia setigera. In vitro, the effect of Sterculia setigera leaves dry hydroethanolic extract (SSE) was tested on cultured cerebellar granule neurons (CGN) survival when exposed to hydrogen peroxide (H2O2) or 6-hydroxydopamine (6-OHDA), using the viability probe fluorescein diacetate (FDA), a lactate dehydrogenase (LDH) activity assay, an immunocytochemical staining against Gap 43, and the quantification of the expression of genes involved in apoptosis, necrosis, or oxidative stress. In vivo, the effect of intraperitoneal (ip) injection of SSE was assessed on the developing brain of 8-day-old Wistar rats exposed to ethanol neurotoxicity by measuring caspase-3 activity on cerebellum homogenates, the expression of some genes in tissue extracts, the thickness of cerebellar cortical layers and motor coordination. In vitro, SSE protected CGN against H2O2 and 6-OHDA-induced cell death at a dose of 10 µg/mL, inhibited the expression of genes Casp3 and Bad, and upregulated the expression of Cat and Gpx7. In vivo, SSE significantly blocked the deleterious effect of ethanol by reducing the activity of caspase-3, inhibiting the expression of Bax and Tp53, preventing the reduction of the thickness of the internal granule cell layer of the cerebellar cortex, and restoring motor functions. Sterculia setigera exerts neuroactive functions as claimed by traditional medicine and should be a good candidate for the development of a neuroprotective treatment against neurodegenerative diseases.

Polyphenolic Compounds: Orchestrating Intestinal Microbiota Harmony during Aging

In the aging process, physiological decline occurs, posing a substantial threat to the physical and mental well-being of the elderly and contributing to the onset of age-related diseases. While traditional perspectives considered the maintenance of life as influenced by a myriad of factors, including environmental, genetic, epigenetic, and lifestyle elements such as exercise and diet, the pivotal role of symbiotic microorganisms had been understated. Presently, it is acknowledged that the intestinal microbiota plays a profound role in overall health by signaling to both the central and peripheral nervous systems, as well as other distant organs. Disruption in this bidirectional communication between bacteria and the host results in dysbiosis, fostering the development of various diseases, including neurological disorders, cardiovascular diseases, and cancer. This review aims to delve into the intricate biological mechanisms underpinning dysbiosis associated with aging and the clinical ramifications of such dysregulation. Furthermore, we aspire to explore bioactive compounds endowed with functional properties capable of modulating and restoring balance in this aging-related dysbiotic process through epigenetics alterations.

Corinthian Currants Promote the Expression of Paraoxonase-1 and Enhance the Antioxidant Status in Serum and Brain of 5xFAD Mouse Model of Alzheimer's Disease

Paraoxonase-1 (PON1), a serum antioxidant enzyme, has been implicated in Alzheimer's disease (AD) pathogenesis that involves early oxidative damage. Corinthian currants and their components have been shown to display antioxidant and other neuroprotective effects in AD. We evaluated the effect of a Corinthian currant paste-supplemented diet (CurD), provided to 1-month-old 5xFAD mice for 1, 3, and 6 months, on PON1 activity and levels of oxidation markers in serum and the brain of mice as compared to a control diet (ConD) or glucose/fructose-matched diet (GFD). Administration of CurD for 1 month increased PON1 activity and decreased oxidized lipid levels in serum compared to ConD and GFD. Longer-term administration of CurD did not, however, affect serum PON1 activity and oxidized lipid levels. Furthermore, CurD administered for 1 and 3 months, but not for 6 months, increased PON1 activity and decreased free radical levels in the cortex of mice compared to ConD and GFD. To probe the mechanism for the increased PON1 activity in mice, we studied the effect of Corinthian currant polar phenolic extract on PON1 activity secreted by Huh-7 hepatocytes or HEK293 cells transfected with a PON1-expressing plasmid. Incubation of cells with the extract led to a dose-dependent increase of secreted PON1 activity, which was attributed to increased cellular PON1 expression. Collectively, our findings suggest that phenolics in Corinthian currants can increase the hepatic expression and activity of antioxidant enzyme PON1 and that a Corinthian currant-supplemented diet during the early stages of AD in mice reduces brain oxidative stress.

Dietary Cocoa Flavanols Do Not Alter Brain Excitability in Young Healthy Adults

The ingestion of dietary cocoa flavanols acutely alters functions of the cerebral endothelium, but whether the effects of flavanols permeate beyond this to alter other brain functions remains unclear. Based on converging evidence, this work tested the hypothesis that cocoa flavanols would alter brain excitability in young healthy adults. In a randomised, cross-over, double-blinded, placebo-controlled design, transcranial magnetic stimulation was used to assess corticospinal and intracortical excitability before as well as 1 and 2 h post-ingestion of a beverage containing either high (695 mg flavanols, 150 mg (-)-epicatechin) or low levels (5 mg flavanols, 0 mg (-)-epicatechin) of cocoa flavanols. In addition to this acute intervention, the effects of a short-term chronic intervention where the same cocoa flavanol doses were ingested once a day for 5 consecutive days were also investigated. For both the acute and chronic interventions, the results revealed no robust alteration in corticospinal or intracortical excitability. One possibility is that cocoa flavanols yield no net effect on brain excitability, but predominantly alter functions of the cerebral endothelium in young healthy adults. Future studies should increase intervention durations to maximize the acute and chronic accumulation of flavanols in the brain, and further investigate if cocoa flavanols would be more effective at altering brain excitability in older adults and clinical populations than in younger adults.

Impact of micronutrients and nutraceuticals on cognitive function and performance in Alzheimer's disease

Alzheimer's disease (AD) is a major global health problem today and is the most common form of dementia. AD is characterized by the formation of β-amyloid (Aβ) plaques and neurofibrillary clusters, leading to decreased brain acetylcholine levels in the brain. Another mechanism underlying the pathogenesis of AD is the abnormal phosphorylation of tau protein that accumulates at the level of neurofibrillary aggregates, and the areas most affected by this pathological process are usually the cholinergic neurons in cortical, subcortical, and hippocampal areas. These effects result in decreased cognitive function, brain atrophy, and neuronal death. Malnutrition and weight loss are the most frequent manifestations of AD, and these are also associated with greater cognitive decline. Several studies have confirmed that a balanced low-calorie diet and proper nutritional intake may be considered important factors in counteracting or slowing the progression of AD, whereas a high-fat or hypercholesterolemic diet predisposes to an increased risk of developing AD. Especially, fruits, vegetables, antioxidants, vitamins, polyunsaturated fatty acids, and micronutrients supplementation exert positive effects on aging-related changes in the brain due to their antioxidant, anti-inflammatory, and radical scavenging properties. The purpose of this review is to summarize some possible nutritional factors that may contribute to the progression or prevention of AD, understand the role that nutrition plays in the formation of Aβ plaques typical of this neurodegenerative disease, to identify some potential therapeutic strategies that may involve some natural compounds, in delaying the progression of the disease.

Phenolic Compounds of Therapeutic Interest in Neuroprotection

The number of elderly people is projected to double in the next 50 years worldwide, resulting in an increased prevalence of neurodegenerative diseases. Aging causes changes in brain tissue homeostasis, thus contributing to the development of neurodegenerative disorders. Current treatments are not entirely effective, so alternative treatments or adjuvant agents are being actively sought. Antioxidant properties of phenolic compounds are of particular interest for neurodegenerative diseases whose psychopathological mechanisms strongly rely on oxidative stress at the brain level. Moreover, phenolic compounds display other advantages such as the permeability of the blood-brain barrier (BBB) and the interesting molecular mechanisms that we reviewed in this work. We began by briefly outlining the physiopathology of neurodegenerative diseases to understand the mechanisms that result in irreversible brain damage, then we provided an overall classification of the phenolic compounds that would be addressed later. We reviewed in vitro and in vivo studies, as well as some clinical trials in which neuroprotective mechanisms were demonstrated in models of different neurodegenerative diseases such as amyotrophic lateral sclerosis (ALS), Alzheimer's disease (AD), Parkinson's disease (PD), ischemia, and traumatic brain injury (TBI).

Ellagic Acid Prevents α-Synuclein Spread and Mitigates Toxicity by Enhancing Autophagic Flux in an Animal Model of Parkinson's Disease

Parkinson's disease (PD) is the second most common neurological disorder, pathologically characterized by loss of dopaminergic neurons in the substantia nigra pars compacta (SNc) as well as the formation of Lewy bodies composed mainly of α-synuclein (α-syn) aggregates. It has been documented that abnormal aggregation of α-syn is one of the major causes of developing PD. In the current study, administration of ellagic acid (EA), a polyphenolic compound (10 mg/kg bodyweight), significantly decreased α-syn spreading and preserved dopaminergic neurons in a male C57BL/6 mouse model of PD. Moreover, EA altered the autophagic flux, suggesting the involvement of a restorative mechanism meditated by EA treatment. Our data support that EA could play a major role in the clearing of toxic α-syn from spreading, in addition to the canonical antioxidative role, and thus preventing dopaminergic neuronal death.

Microbiome in Cancer Development and Treatment

Targeting the microbiome, microbiota-derived metabolites, and related pathways represents a significant challenge in oncology. Microbiome analyses have confirmed the negative impact of cancer treatment on gut homeostasis, resulting in acute dysbiosis and severe complications, including massive inflammatory immune response, mucosal barrier disruption, and bacterial translocation across the gut epithelium. Moreover, recent studies revealed the relationship between an imbalance in the gut microbiome and treatment-related toxicity. In this review, we provide current insights into the role of the microbiome in tumor development and the impact of gut and tumor microbiomes on chemo- and immunotherapy efficacy, as well as treatment-induced late effects, including cognitive impairment and cardiotoxicity. As discussed, microbiota modulation via probiotic supplementation and fecal microbiota transplantation represents a new trend in cancer patient care, aiming to increase bacterial diversity, alleviate acute and long-term treatment-induced toxicity, and improve the response to various treatment modalities. However, a more detailed understanding of the complex relationship between the microbiome and host can significantly contribute to integrating a microbiome-based approach into clinical practice. Determination of causal correlations might lead to the identification of clinically relevant diagnostic and prognostic microbial biomarkers. Notably, restoration of intestinal homeostasis could contribute to optimizing treatment efficacy and improving cancer patient outcomes.

Mediterranean Shrub Species as a Source of Biomolecules against Neurodegenerative Diseases

Neurodegenerative diseases are associated with oxidative stress, due to an imbalance in the oxidation-reduction reactions at the cellular level. Various treatments are available to treat these diseases, although they often do not cure them and have many adverse effects. Therefore, it is necessary to find complementary and/or alternative drugs that replace current treatments with fewer side effects. It has been demonstrated that natural products derived from plants, specifically phenolic compounds, have a great capacity to suppress oxidative stress and neutralize free radicals thus, they may be used as alternative alternative pharmacological treatments for pathological conditions associated with an increase in oxidative stress. The plant species that dominate the Mediterranean ecosystems are characterized by having a wide variety of phenolic compound content. Therefore, these species might be important sources of neuroprotective biomolecules. To evaluate this potential, 24 typical plant species of the Mediterranean ecosystems were selected, identifying the most important compounds present in them. This set of plant species provides a total of 403 different compounds. Of these compounds, 35.7% are phenolic acids and 55.6% are flavonoids. The most relevant of these compounds are gallic, vanillic, caffeic, chlorogenic, p-coumaric, and ferulic acids, apigenin, kaempferol, myricitrin, quercetin, isoquercetin, quercetrin, rutin, catechin and epicatechin, which are widely distributed among the analyzed plant species (in over 10 species) and which have been involved in the literature in the prevention of different neurodegenerative pathologies. It is also important to mention that three of these plant species, Pistacea lentiscus, Lavandula stoechas and Thymus vulgaris, have most of the described compounds with protective properties against neurodegenerative diseases. The present work shows that the plant species that dominate the studied geographic area can provide an important source of phenolic compounds for the pharmacological and biotechnological industry to prepare extracts or isolated compounds for therapy against neurodegenerative diseases.

Neuroprotective effect of Tiliacora triandra (Colebr.) Diels leaf extract on scopolamine-induced memory impairment in rats

Alzheimer's disease is characterized by progressive memory loss caused from alterations in the central cholinergic system. While existing medications often have adverse effects, traditional use of Tiliacora triandra in Thailand shows its potential as a revitalizing neurotonic agent. This study explores the impact of T. triandra leaf extract on cognitive behaviors, neuronal density, and oxidative stress in male rats with scopolamine-induced cognitive impairment. Experimental groups composed of a control, vehicle, positive control meditation, and T. triandra extract-treated groups (100, 200, and 400 mg/kg BW) over 14 days, with scopolamine administration (i.p.) between days 8 and 14. Results showed significant enhancements in the discrimination ratio and spontaneous alteration behavior percentage during novel object recognition (NORT) and Y-maze tests for scopolamine-administered rats treated with T. triandra extract or donepezil. In contrast, open field test (OFT)-assessed spontaneous locomotor activity displayed no significant difference. Notably, acetylcholinesterase (AChE) activity and malondialdehyde (MDA) levels reduced significantly in scopolamine-treated rats with T. triandra extract or the positive control. Moreover, neuronal density in the hippocampal CA3 region, superoxide dismutase (SOD), and glutathione peroxidase (GSH-Px) activities increased significantly. However, catalase (CAT) activity exhibited no significant difference. In conclusion, T. triandra leaf extract shows promise in mitigating scopolamine-induced memory deficits, potentially attributed to increased neuronal density, inhibited AChE activity, reduced MDA levels, and enhanced antioxidant activities. This extract has potential as a therapeutic agent for Alzheimer's disease-associated memory impairment.

Costunolide and parthenolide: Novel blood-brain barrier permeable sesquiterpene lactones to improve barrier tightness

Sesquiterpene lactones - such as those found in chicory - are considered promising bioactive compounds. These small molecules have shown several health benefits for various diseases, including brain disorders. However, it is unknown whether these compounds can cross the blood-brain barrier (BBB), and which could be the effects on brain microvascular endothelial cells. We show that six sesquiterpene lactones evaluated in an in vitro model of the BBB have different capacities to be transported through the barrier. Costunolide presented more than 20 % of transport while lactucin, 11β-13-dihydrolactucin, 11β-13-dihydrolactucopicrin, and parthenolide presented between 10 % and 20 %, whilst almost no transport was detected for lactucopicrin. Furthermore, costunolide and parthenolide reduced P-gp ABC transporter expression alongside an increase in caveolin-1, the main protein of caveolae. Remarkably, these two compounds improved barrier tightness by increasing the expression of both tight and adherens junctions. These findings open a new avenue to explore costunolide and parthenolide as promising compounds for brain therapies.

4-Ethylphenol-fluxes, metabolism and excretion of a gut microbiome derived neuromodulator implicated in autism

Gut-microbiome-derived metabolites, such as 4-Ethylphenol [4EP], have been shown to modulate neurological health and function. Although the source of such metabolites is becoming better understood, knowledge gaps remain as to the mechanisms by which they enter host circulation, how they are transported in the body, how they are metabolised and excreted, and the way they exert their effects. High blood concentrations of host-modified 4EP, 4-ethylphenol sulfate [4EPS], are associated with an anxiety phenotype in autistic individuals. We have reviewed the existing literature and discuss mechanisms that are proposed to contribute influx from the gut microbiome, metabolism, and excretion of 4EP. We note that increased intestinal permeability is common in autistic individuals, potentially explaining increased flux of 4EP and/or 4EPS across the gut epithelium and the Blood Brain Barrier [BBB]. Similarly, kidney dysfunction, another complication observed in autistic individuals, impacts clearance of 4EP and its derivatives from circulation. Evidence indicates that accumulation of 4EPS in the brain of mice affects connectivity between subregions, particularly those linked to anxiety. However, we found no data on the presence or quantity of 4EP and/or 4EPS in human brains, irrespective of neurological status, likely due to challenges sampling this organ. We argue that the penetrative ability of 4EP is dependent on its form at the BBB and its physicochemical similarity to endogenous metabolites with dedicated active transport mechanisms across the BBB. We conclude that future research should focus on physical (e.g., ingestion of sorbents) or metabolic mechanisms (e.g., conversion to 4EP-glucuronide) that are capable of being used as interventions to reduce the flux of 4EP from the gut into the body, increase the efflux of 4EP and/or 4EPS from the brain, or increase excretion from the kidneys as a means of addressing the neurological impacts of 4EP.

Identification and quantification of (poly)phenol and methylxanthine metabolites in human cerebrospinal fluid: evidence of their ability to cross the BBB

Increasing evidence suggests that dietary (poly)phenols and methylxanthines have neuroprotective effects; however, little is known about whether they can cross the blood-brain barrier (BBB) and exert direct effects on the brain. We investigated the presence of (poly)phenol and methylxanthine metabolites in plasma and cerebrospinal fluid (CSF) from 90 individuals at risk of dementia using liquid chromatography-mass spectrometry and predicted their mechanism of transport across the BBB using in silico modelling techniques. A total of 123 and 127 metabolites were detected in CSF and plasma, respectively. In silico analysis suggests that 5 of the 20 metabolites quantified in CSF can cross the BBB by passive diffusion, while at least 9 metabolites require the aid of cell transporters to cross the BBB. Our results showed that (poly)phenols and methylxanthines are bioavailable, can cross the BBB via passive diffusion or transport carriers, and can reach brain tissues to exert neuroprotective effects.

A dietary polyphenol metabolite alters CA1 excitability ex vivo and mildly affects cortico-hippocampal field potential generators in anesthetized animals

Dietary polyphenols have beneficial effects in situations of impaired cognition in acute models of neurodegeneration. The possibility that they may have a direct effect on the electrical activity of neuronal populations has not been tested. We explored the electrophysiological action of protocatechuic acid (PCA) on CA1 pyramidal cells ex vivo and network activity in anesthetized female rats using pathway-specific field potential (FP) generators obtained from laminar FPs in cortex and hippocampus. Whole-cell recordings from CA1 pyramidal cells revealed increased synaptic potentials, particularly in response to basal dendritic excitation, while the associated evoked firing was significantly reduced. This counterintuitive result was attributed to a marked increase of the rheobase and voltage threshold, indicating a decreased ability to generate spikes in response to depolarizing current. Systemic administration of PCA only slightly altered the ongoing activity of some FP generators, although it produced a striking disengagement of infraslow activities between the cortex and hippocampus on a scale of minutes. To our knowledge, this is the first report showing the direct action of a dietary polyphenol on electrical activity, performing neuromodulatory roles at both the cellular and network levels.

Polyphenols and Their Impact on the Prevention of Neurodegenerative Diseases and Development

It is well known that neurodegenerative diseases' development and progression are accelerated due to oxidative stress and inflammation, which result in impairment of mitochondrial function, cellular damage, and dysfunction of DNA repair systems. The increased consumption of antioxidants can postpone the development of these disorders and improve the quality of patients' lives who have already been diagnosed with neurodegenerative diseases. Prolonging life span in developed countries contributes to an increase in the incidence ratio of chronic age-related neurodegenerative disorders, such as PD (Parkinson's disease), AD (Alzheimer's disease), or numerous forms of age-related dementias. Dietary supplementation with neuroprotective plant-derived polyphenols might be considered an important element of healthy aging. Some polyphenols improve cognition, mood, visual functions, language, and verbal memory functions. Polyphenols bioavailability differs greatly from one compound to another and is determined by solubility, degree of polymerization, conjugation, or glycosylation resulting from chemical structure. It is still unclear which polyphenols are beneficial because their potential depends on efficient transport across the BBB (blood-brain barrier), bioavailability, and stability in the CNS (central nervous system). Polyphenols improve brain functions by having a direct impact on cells and processes in the CNS. For a direct effect, polyphenolic compounds must be able to overcome the BBB and accumulate in brain tissue. In this review, the latest achievements in studies (animal models and clinical trials) on the effect of polyphenols on brain activity and function are described. The beneficial impact of plant polyphenols on the brain may be summarized by their role in increasing brain plasticity and related cognition improvement. As reversible MAO (monoamine oxidase) inhibitors, polyphenols are mood modulators and improve neuronal self-being through an increase in dopamine, serotonin, and noradrenaline amounts in the brain tissue. After analyzing the prohealth effects of various eating patterns, it was postulated that their beneficial effects result from synergistic interactions between individual dietary components. Polyphenols act on the brain endothelial cells and improve the BBB's integrity and reduce inflammation, thus protecting the brain from additional injury during stroke or autoimmune diseases. Polyphenolic compounds are capable of lowering blood pressure and improving cerebral blood flow. Many studies have revealed that a nutritional model based on increased consumption of antioxidants has the potential to ameliorate the cognitive impairment associated with neurodegenerative disorders. Randomized clinical trials have also shown that the improvement of cognitive functions resulting from the consumption of foods rich in flavonoids is independent of age and health conditions. For therapeutic use, sufficient quantities of polyphenols must cross the BBB and reach the brain tissue in active form. An important issue in the direct action of polyphenols on the CNS is not only their penetration through the BBB, but also their brain metabolism and localization. The bioavailability of polyphenols is low. The most usual oral administration also conflicts with bioavailability. The main factors that limit this process and have an effect on therapeutic efficacy are: selective permeability across BBB, gastrointestinal transformations, poor absorption, rapid hepatic and colonic metabolism, and systemic elimination. Thus, phenolic compounds have inadequate bioavailability for human applications to have any beneficial effects. In recent years, new strategies have been attempted in order to exert cognitive benefits and neuroprotective effects. Converting polyphenols into nanostructures is one of the theories proposed to enhance their bioavailability. The following nanoscale delivery systems can be used to encapsulate polyphenols: nanocapsules, nanospheres, micelles, cyclodextrins, solid lipid nanoparticles, and liposomes. It results in great expectations for the wide-scale and effective use of polyphenols in the prevention of neurodegenerative diseases. Thus far, only natural polyphenols have been studied as neuroprotectors. Perhaps some modification of the chemical structure of a given polyphenol may increase its neuroprotective activity and transportation through the BBB. However, numerous questions should be answered before developing neuroprotective medications based on plant polyphenols.

Bioactive Compounds for Customized Brain Health: What Are We and Where Should We Be Heading?

Many strides have been made in the field of nutrition that are making it an attractive field not only to nutrition professionals but also to healthcare practitioners. Thanks to the emergence of molecular nutrition, there is a better appreciation of how the diet modulates health at the cellular and molecular levels. More importantly, the advancements in brain imaging have produced a greater appreciation of the impact of diet on brain health. To date, our understanding of the effect of nutrients on brain health goes beyond the action of vitamins and minerals and dives into the intracellular, molecular, and epigenetic effects of nutrients. Bioactive compounds (BCs) in food are gaining a lot of attention due to their ability to modulate gene expression. In addition, bioactive compounds activate some nuclear receptors that are the target of many pharmaceuticals. With the emergence of personalized medicine, gaining an understanding of the biologically active compounds may help with the customization of therapies. This review explores the prominent BCs that can impact cognitive functions and mental health to deliver a potentially prophylactic framework for practitioners. Another purpose is to identify potential gaps in the literature to suggest new research agendas for scientists.

Cracking Brain Diseases from Gut Microbes-Mediated Metabolites for Precise Treatment

The gut-brain axis has been a subject of significant interest in recent years. Understanding the link between the gut and brain axis is crucial for the treatment of disorders. Here, the intricate components and unique relationship between gut microbiota-derived metabolites and the brain are explained in detail. Additionally, the association between gut microbiota-derived metabolites and the integrity of the blood-brain barrier and brain health is emphasized. Meanwhile, gut microbiota-derived metabolites with their recent applications, challenges and opportunities their pathways on different disease treatment are focus discussed. The prospective strategy of gut microbiota-derived metabolites potential applies to the brain disease treatments, such as Parkinson's disease and Alzheimer's disease, is proposed. This review provides a broad perspective on gut microbiota-derived metabolites characteristics facilitate understand the connection between gut and brain and pave the way for the development of a new medication delivery system for gut microbiota-derived metabolites.

Antiparkinsonian Effects of Polyphenols: A Narrative Review with a Focus on the Modulation of the Gut-brain Axis

Polyphenols, which are naturally occurring bioactive compounds in fruits and vegetables, are emerging as potential therapeutics for neurological disorders such as Parkinson's disease (PD). Polyphenols have diverse biological activities, such as anti-oxidative, anti-inflammatory, anti-apoptotic, and α-synuclein aggregation inhibitory effects, which could ameliorate PD pathogenesis. Studies have shown that polyphenols are capable of regulating the gut microbiota (GM) and its metabolites; in turn, polyphenols are extensively metabolized by the GM, resulting in the generation of bioactive secondary metabolites. These metabolites may regulate various physiological processes, including inflammatory responses, energy metabolism, intercellular communication, and host immunity. With increasing recognition of the importance of the microbiota-gut-brain axis (MGBA) in PD etiology, polyphenols have attracted growing attention as MGBA regulators. In order to address the potential therapeutic role of polyphenolic compounds in PD, we focused on MGBA. DATA AVAILABILITY: Data will be made available on request.

Dietary (Poly)phenols in Traumatic Brain Injury

Traumatic brain injury (TBI) remains one of the leading causes of death and disability in young adults worldwide. Despite growing evidence and advances in our knowledge regarding the multifaceted pathophysiology of TBI, the underlying mechanisms, though, are still to be fully elucidated. Whereas initial brain insult involves acute and irreversible primary damage to the brain, the processes of subsequent secondary brain injury progress gradually over months to years, providing a window of opportunity for therapeutic interventions. To date, extensive research has been focused on the identification of druggable targets involved in these processes. Despite several decades of successful pre-clinical studies and very promising results, when transferred to clinics, these drugs showed, at best, modest beneficial effects, but more often, an absence of effects or even very harsh side effects in TBI patients. This reality has highlighted the need for novel approaches that will be able to respond to the complexity of the TBI and tackle TBI pathological processes on multiple levels. Recent evidence strongly indicates that nutritional interventions may provide a unique opportunity to enhance the repair processes after TBI. Dietary (poly)phenols, a big class of compounds abundantly found in fruits and vegetables, have emerged in the past few years as promising agents to be used in TBI settings due to their proven pleiotropic effects. Here, we give an overview of the pathophysiology of TBI and the underlying molecular mechanisms, followed by a state-of-the-art summary of the studies that have evaluated the efficacy of (poly)phenols administration to decrease TBI-associated damage in various animal TBI models and in a limited number of clinical trials. The current limitations on our knowledge concerning (poly)phenol effects in TBI in the pre-clinical studies are also discussed.