Long-term administration of resveratrol at low doses improves neurocognitive performance as well as cerebral blood flow and modulates the inflammatory pathways in the brain

The Cognitive Restoration Effects of Resveratrol: Insight Molecular through Behavioral Studies in Various Cognitive Impairment Models

Cognition is essential for daily activities and progressively deteriorates with age due to various factors leading to cognitive decline. This decline often begins with memory impairment and advances to broader cognitive dysfunctions. Resveratrol (RES), a natural phenolic compound found in red wine, has garnered significant attention for its potential to prevent cognitive decline. This review aims to synthesize the latest preclinical data on the cognitive restorative effects of RES. We highlight RES activities from cellular mechanisms to behavioral outcomes. Evidence from various cognitive impairment models demonstrates that RES exerts neuroprotective effects through multiple mechanisms, including anti-inflammatory, antioxidative, anti-apoptotic, and neurotrophic actions, all of which contribute to cognitive enhancement in behavioral studies. Despite the established role of RES in mitigating memory decline, our review identifies a critical gap in behavioral studies regarding cognitive flexibility. Further research in this domain is recommended. Additionally, species-specific pharmacokinetic differences may account for the inconsistencies between preclinical and clinical outcomes, particularly in rats and humans. We propose that formulations designed to delay gut metabolism through enterohepatic circulation could enhance the translational potential of RES. Furthermore, long-term studies are needed to determine the optimal dose capable of maximizing health benefits without raising toxicity during chronic use.

The effect of plant-derived polyphenols on the immune system during aging: a systematic review

OBJECTIVE

Polyphenols are organic compounds with diverse biological activities such as anti-inflammatory and antioxidant effects, making them important candidates for the development of anti-aging drugs. In this systematic review, we aimed to answer the question: can plant-derived polyphenols have an immunomodulatory effect in experimental models of aging?

METHODS

We systematically searched Web of Science, MEDLINE/Pubmed, and Embase to select articles using the following combinations of terms and synonyms: polyphenols, phenols, senescence, aging, and immune. The selected articles were evaluated for reporting quality and risk-of-bias according to standard guidelines.

RESULTS

The most used polyphenol was resveratrol, followed by curcumin, salidroside, and gallic acid. These molecules demonstrated an ability to restore immune function both in vitro and in vivo. The mechanism of action was not completely elucidated in these studies, but inhibition of NF-kB signaling, and antioxidant properties seemed to account for the anti-aging effects. All articles included in the review had good quality of reporting but failed to describe an adequate sample size, criteria for inclusion/exclusion, randomization, and blinding.

CONCLUSION

We conclude that polyphenols are promising immunomodulatory substances for use in anti-aging therapies. However, more research with standardized analysis is needed to understand the role of these molecules in the prevention or reduction of damage associated with the aging process, as well as to determine the safety profile and consequences of systemic action.

Resveratrol: A Multifaceted Guardian against Anxiety and Stress Disorders-An Overview of Experimental Evidence

The medicinal properties of resveratrol have garnered increasing attention from researchers. Extensive data have been accumulated on its use in treating cardiovascular diseases, immune system disorders, cancer, neurological diseases, and behavioral disorders. The protective mechanisms of resveratrol, particularly in anxiety-related stress disorders, have been well documented. However, less attention has been given to the side effects of resveratrol. This review explores not only the mechanisms underlying the anxiolytic effects of resveratrol but also the mechanisms that may lead to increased anxiety following resveratrol treatment. Understanding these mechanisms is crucial for enhancing the efficacy of resveratrol in managing anxiety disorders associated with stress and PTSD.

Microglia and Astrocytes in Alzheimer's Disease: Significance and Summary of Recent Advances

Alzheimer's disease, one of the most common forms of dementia, is characterized by a slow progression of cognitive impairment and neuronal loss. Currently, approved treatments for AD are hindered by various side effects and limited efficacy. Despite considerable research, practical treatments for AD have not been developed. Increasing evidence shows that glial cells, especially microglia and astrocytes, are essential in the initiation and progression of AD. During AD progression, activated resident microglia increases the ability of resting astrocytes to transform into reactive astrocytes, promoting neurodegeneration. Extensive clinical and molecular studies show the involvement of microglia and astrocyte-mediated neuroinflammation in AD pathology, indicating that microglia and astrocytes may be potential therapeutic targets for AD. This review will summarize the significant and recent advances of microglia and astrocytes in the pathogenesis of AD in three parts. First, we will review the typical pathological changes of AD and discuss microglia and astrocytes in terms of function and phenotypic changes. Second, we will describe microglia and astrocytes' physiological and pathological role in AD. These roles include the inflammatory response, "eat me" and "don't eat me" signals, Aβ seeding, propagation, clearance, synapse loss, synaptic pruning, remyelination, and demyelination. Last, we will review the pharmacological and non-pharmacological therapies targeting microglia and astrocytes in AD. We conclude that microglia and astrocytes are essential in the initiation and development of AD. Therefore, understanding the new role of microglia and astrocytes in AD progression is critical for future AD studies and clinical trials. Moreover, pharmacological, and non-pharmacological therapies targeting microglia and astrocytes, with specific studies investigating microglia and astrocyte-mediated neuronal damage and repair, may be a promising research direction for future studies regarding AD treatment and prevention.

Multidimensional biological activities of resveratrol and its prospects and challenges in the health field

Resveratrol (RES) is a naturally occurring polyphenolic compound. Recent studies have identified multiple potential health benefits of RES, including antioxidant, anti-inflammatory, anti-obesity, anticancer, anti-diabetic, cardiovascular, and neuroprotective properties. The objective of this review is to summarize and analyze the studies on the biological activities of RES in disease prevention and treatment, as well as its metabolism and bioavailability. It also discusses the challenges in its clinical application and future research directions. RES exhibits significant potential in the prevention and treatment of many diseases. The future direction of RES research should focus on improving its bioavailability, conducting more clinical trials to determine its effectiveness in humans, and investigating its mechanism of action. Once these challenges have been overcome, RES is expected to become an effective health intervention.

Macrophage migration inhibitor factor (MIF): Potential role in cognitive impairment disorders

Macrophage migration inhibitory factor (MIF) is a cytokine in the immune system, participated in both innate and adaptive immune responses. Except from immune cells, MIF is also secreted by a variety of non-immune cells, including hematopoietic cells, endothelial cells (ECs), and neurons. MIF plays a crucial role in various diseases, such as sepsis, rheumatoid arthritis, acute kidney injury, and neurodegenerative diseases. The role of MIF in the neuropathogenesis of cognitive impairment disorders is emphasized, as it recruits multiple inflammatory mediators, leading to activating microglia or astrocyte-derived neuroinflammation. Furthermore, it contributes to the cell death of neurons and ECs with the binding of apoptosis-inducing factor (AIF) through parthanatos-associated apoptosis-inducing factor nuclease (PAAN) / MIF pathway. This review comprehensively delves into the relationship between MIF and the neuropathogenesis of cognitive impairment disorders, providing a series of emerging MIF-targeted pharmaceuticals as potential treatments for cognitive impairment disorders.

Safety and efficacy of antioxidant therapy in children and adolescents with attention deficit hyperactivity disorder: A systematic review and network meta-analysis

OBJECTIVE

To systematically evaluate the safety and efficacy of antioxidant therapy in children and adolescents with attention deficit hyperactivity disorder (ADHD).

METHODS

Randomized controlled trials and prospective studies on antioxidant therapy in children and adolescents with ADHD were searched in PubMed, Embase, and Cochrane Library from the inception of databases to November 12, 2022. Two investigators independently screened the literature, extracted data, and evaluated the quality of the included studies. Network meta-analysis (PROSPERO registration number CRD 42023382824) was carried out by using R Studio 4.2.1.

RESULTS

48 studies involving 12 antioxidant drugs (resveratrol, pycnogenol, omega-3, omega-6, quercetin, phosphatidylserine, almond, vitamin D, zinc, folic acid, ginkgo biloba, Acetyl-L-carnitine) were finally included, with 3,650 patients. Network meta-analysis showed that omega-6 (0.18), vitamin D (0.19), and quercetin (0.24) were the top three safest drugs according to SUCRA. The omega-3 (SUCRA 0.35), pycnogenol (SUCRA 0.36), and vitamin D (SUCRA 0.27) were the most effective in improving attention, hyperactivity, and total score of Conners' parent rating scale (CPRS), respectively. In terms of improving attention, hyperactivity, and total score of Conners' teacher rating scale (CTRS), pycnogenol (SUCRA 0.32), phosphatidylserine+omega-3 (SUCRA 0.26), and zinc (SUCRA 0.34) were the most effective, respectively. In terms of improving attention, hyperactivity and total score of ADHD Rating Scale-Parent, the optimal agents were phosphatidylserine (SUCRA 0.39), resveratrol+MPH (SUCRA 0.24), and phosphatidylserine (SUCRA 0.34), respectively. In terms of improving attention, hyperactivity and total score of ADHD Rating Scale-Teacher, pycnogenol (SUCRA 0.32), vitamin D (SUCRA 0.31) and vitamin D (SUCRA 0.18) were the optimal agents, respectively. The response rate of omega-3+6 was the highest in CGI (SUCRA 0.95) and CPT (SUCRA 0.42).

CONCLUSION

The rankings of safety and efficacy of the 12 antioxidants vary. Due to the low methodological quality of the included studies, the probability ranking cannot fully explain the clinical efficacy, and the results need to be interpreted with caution. More high-quality studies are still needed to verify our findings.

Alzheimer, Parkinson, dementia, and phytochemicals: insight review

Alzheimer's, Parkinson's, and dementia are the leading neurodegenerative diseases that threaten the world with the aging population. Although the pathophysiology of each disease is unique, the steps to be taken to prevent diseases are similar. One of the changes that a person can make alone is to gain the habit of an antioxidant-rich diet. Phytochemicals known for their antioxidant properties have been reported to prevent neurodegenerative diseases in various studies. Phytochemicals with similar chemical structures are grouped. Accordingly, there are two main groups of phytochemicals, flavonoid and non-flavonoid. Various in vitro and in vivo studies on phytochemicals have proven neuroprotective effects by increasing cognitive function with their anti-inflammatory and antioxidant mechanisms. The purpose of this review is to summarize the in vitro and in vivo studies on phytochemicals with neuroprotective effects and to provide insight.

Immunosenescence and Inflamm-Aging: Clinical Interventions and the Potential for Reversal of Aging

Inflammation is often associated with the impairment of the ability to sustain the consequences of the physical, chemical, nutritional, and antigenic triggers of inflammation. The process of immunosenescence may only partially be explained by the senescence of cells, tissues, or the organism, and, hence, the hallmarks of immunosenescence may be markedly and differentially affected by the history of an individual's pathogenic encounter. Inflammation is a key component of immunosenescence, which itself is a direct consequence of aging. This review article highlights the therapeutic interventions for slowing the processes of inflamm-aging and immunosenescence and the possible reversal of aging and includes domains of immunomodulatory interventions, vaccination strategies, nutritional interventions, stem cell therapies, personalized medicine, microbiome interventions, and the positive effects of physical activity and exercise.

Resveratrol and Its Analogues: Anti-ageing Effects and Underlying Mechanisms

Ageing is a natural process accompanied by functional and structural decline of diverse tissues and organs, which could cause susceptibility to various diseases and death. The anti-ageing interventions have aroused huge research interest with the rapid rise of ageing population in the world. Resveratrol, a polyphenolic stilbene, could be naturally isolated from various plants, such as grapes, blueberries, and peanuts. Many studies indicated that resveratrol possessed a broad spectrum of bioactivities, especially anti-ageing activity. A lot of attention has also been focused on resveratrol analogues because they have a similar structure to resveratrol, which may confer them a potent anti-ageing effect. The anti-ageing mechanisms of resveratrol and its analogues are complex and multifactorial, involving suppressing oxidative stress, ameliorating inflammation, activating SIRT1 pathway, reducing DNA damage, etc. In this chapter, the anti-ageing effects of resveratrol and its analogues are summarised with special attention paid to the underlying mechanisms. Further understanding of these small molecules could provide the necessary scientific basis for their development into anti-ageing agents.

Effect and mechanisms of resveratrol in animal models of ischemic stroke: A systematic review and Bayesian meta-analysis

Resveratrol (RSV) holds promise as cerebroprotective treatment in cerebral ischemia. This systematic review aims to assess the effects and mechanisms of RSV in animal models of ischemic stroke. We searched Medline, Embase and Web of Science to identify 75 and 57 eligible rodent studies for qualitative and quantitative syntheses, respectively. Range of evidence met 10 of 13 STAIR criteria. Median (Q1, Q3) quality score was 7 (5, 8) on the CAMARADES 15-item checklist. Bayesian meta-analysis showed SMD estimates (95% CI) favoring RSV: infarct size (-1.72 [-2.03; -1.41]), edema size (-1.61 [-2.24; -0.98]), BBB impairment (-1.85 [-2.54; -1.19]), neurofunctional impairment (-1.60 [-1.92; -1.29]), and motor performance (1.39 [0.64; 2.08]); and less probably neuronal survival (0.63 [-1.40; 2.48]) and apoptosis (-0.96 [-2.87; 1.02]). Species (rat vs mouse) was associated to a larger benefit. Sensitivity analyses confirmed robustness of the estimates. Reduction of oxidative stress, inflammation, and apoptosis underlie these effects. Our results quantitatively state the beneficial effects of RSV on structural and functional outcomes in rodent stroke models, update the evidence on the mechanisms of action, and provide an exhaustive list of targeted signaling pathways. Current evidence highlights the need for conducting further high-quality preclinical research to better inform clinical research.

Neurovascular glial unit: A target of phytotherapy for cognitive impairments

BACKGROUND

Neurovascular glial unit (NVGU) dysfunction has been reported to be an early and critical event in the pathophysiology of Alzheimer's disease (AD) and vascular dementia (VD). Although herbal medicines, with their favorable safety profiles and low adverse effects, have been suggested to be useful for the treatment of cognitive impairment, the potential role of the NVGU as the target of the effects of herbal medicines is still unclear.

PURPOSE

This review aimed to retrieve evidence from experimental studies of phytopharmaceuticals targeting the NVGU for the treatment of cognitive impairment in AD and VD, and discussed the potential of phytopharmaceuticals to improve cognitive impairment from the perspective of the NVGU.

STUDY DESIGN AND METHODS

We systematically searched PubMed, Google Scholar, Web of Science, and CNKI. The keywords used for searching information on the NVGU in the treatment of cognitive impairments included "Alzheimer's disease," "Vascular dementia," "Herbal medicines," "Natural products," "Neurovascular," "Adverse reaction," and "Toxicity, etc." We selected studies on the basis of predefined eligibility criteria.

RESULTS

NVGU mainly consists of endothelial cells, pericytes, astrocytes, microglia, oligodendrocytes, and neurons, and damage to these cells can induce cognitive impairment by impairing the blood-brain barrier (BBB) and cerebral blood flow (CBF) as well as neuronal function. The active components of herbal medicines, including Ginkgo biloba L., Ginseng Radix et Rhizoma, Epimedium Folium, Chuanxiong Rhizoma, Carthami flos, and Acorus tatarinowii Schott, as well as traditional Chinese medicine prescriptions have shown the potential to improve BBB function and increase CBF to prevent cognitive impairment by inhibiting astrocyte and microglia activation, protecting oligodendrocyte myelin function, reducing neuronal apoptosis, and promoting angiogenesis.

CONCLUSIONS

Herbal medicines demonstrate great potential to prevent cognitive impairment. Multiple components from herbal medicines may function through different signaling pathways to target the NVGU. Future studies using novel drug-carrier or delivery systems targeting the NVGU will certainly facilitate the development of phytopharmaceuticals for AD and VD.

Mechanism of Resveratrol Improving Ischemia-Reperfusion Injury by Regulating Microglial Function Through microRNA-450b-5p/KEAP1/Nrf2 Pathway

Alterations in the M1/M2 polarization phenotype significantly affect disease progression. Antioxidant and anti-inflammatory protective effects of resveratrol (Res) have been demonstrated. This paper tested the hypothesis that Res could protect against cerebral ischemia-reperfusion injury (CI/RI) by modulating microglial polarization via the miR-450b-5p/KEAP1/Nrf2 pathway. Rats were first treated with Res and adenovirus that interfered with miR-450b-5p or KEAP1, and then established a middle cerebral artery occlusion-reperfusion model using modified nylon sutures. Rats were then evaluated for neurological and behavioral functions, and markers of M2 microglia were detected by immunofluorescence staining. Additionally, the signature patterns of miR-450b-5p, KEAP1, and Nrf2 were determined. The collected data demonstrated that Res exerted neuroprotective effects in CI/RI by promoting microglial M2 polarization. Additionally, Res could regulate the Nrf2 pathway by targeting KEAP1 by up-regulating miR-450b-5p. Up-regulating miR-450b-5p or down-regulating KEAP1 could further promote the protective effect of Res, while down-regulating miR-450b-5p or up-regulating KEAP1 worked oppositely. Our study demonstrates that Res exerts neuroprotective effects on microglial M2 polarization through the miR-450b-5p/KEAP1/Nrf2 pathway during CI/RI.

Glioprotective effects of resveratrol in hypothalamic astrocyte cultures obtained from interferon receptor knockout (IFNα/βR-/-) mice

Astrocytes play essential roles in the central nervous system (CNS), such as the regulation of glutamate metabolism, antioxidant defenses, and inflammatory/immune responses. Moreover, hypothalamic astrocytes seem to be crucial in the modulation of inflammatory processes, including those related to type I interferon signaling. In this regard, the polyphenol resveratrol has emerged as an important glioprotective molecule to regulate astrocyte functions. Therefore, this study aimed to investigate the immunomodulatory and protective effects of resveratrol in hypothalamic astrocyte cultures obtained from mouse depleted of type I interferon receptors (INF-α/β^-/-), a condition that can impair immune and inflammatory functions. Resveratrol upregulated glutamate transporter and glutamine synthetase gene expression, as well as modulated the release of wide range of cytokines and genes involved in the control of inflammatory response, besides the expression of adenosine receptors, which display immunomodulatory functions. Resveratrol also increased genes associated with redox balance, mitochondrial processes, and trophic factors signaling. The putative genes associated with glioprotective effects of resveratrol, including nuclear factor erythroid derived 2 like 2 (Nrf2), heme oxygenase 1 (HO-1), sirtuin 1 (SIRT1), and phosphoinositide 3-kinase (PI3K)/Akt, were further upregulated by resveratrol. Thus, our data show that resveratrol was able to modulate key genes associated with glial functionality and inflammatory response in astrocyte cultures derived from IFNα/βR^-/- mice. These data are in agreement with previous results, reinforcing its glioprotective effects even in hypothalamic astrocytes with altered inflammatory and immune signaling. Finally, this polyphenol can prepare astrocytes to better respond to injuries, including those associated with neuroimmunology defects.

Dietary Polyphenols as a Protection against Cognitive Decline: Evidence from Animal Experiments; Mechanisms and Limitations

Emerging evidence suggests that cognitive impairments may result from various factors, such as neuroinflammation, oxidative stress, mitochondrial damage, impaired neurogenesis, synaptic plasticity, blood-brain barrier (BBB) disruption, amyloid β protein (Aβ) deposition, and gut dysbiosis. Meanwhile, dietary polyphenol intake in a recommended dosage has been suggested to reverse cognitive dysfunction via various pathways. However, excessive intake of polyphenols could trigger unwanted adverse effects. Thus, this review aims to outline possible causes of cognitive impairments and how polyphenols alleviate memory loss via various pathways based on in vivo experimental studies. Thus, to identify potentially relevant articles, the keywords (1) nutritional polyphenol intervention NOT medicine AND neuron growth OR (2) dietary polyphenol AND neurogenesis AND memory impairment OR (3) polyphenol AND neuron regeneration AND memory deterioration (Boolean operators) were used in the Nature, PubMed, Scopus, and Wiley online libraries. Based on the inclusion and exclusion criteria, 36 research papers were selected to be further reviewed. The outcome of all the studies included supports the statement of appropriate dosage by taking into consideration gender differences, underlying conditions, lifestyle, and causative factors for cognitive decline, which will significantly boost memory power. Therefore, this review recapitulates the possible causes of cognitive decline, the mechanism of polyphenols involving various signaling pathways in modulating the memory, gut dysbiosis, endogenous antioxidants, bioavailability, dosage, and safety efficacy of polyphenols. Hence, this review is expected to provide a basic understanding of therapeutic development for cognitive impairments in the future.

Emerging cellular senescence-centric understanding of immunological aging and its potential modulation through dietary bioactive components

Immunological aging is strongly associated with the observable deleterious effects of human aging. Our understanding of the causes, effects, and therapeutics of aging immune cells has long been considered within the sole purview of immunosenescence. However, it is being progressively realized that immunosenescence may not be the only determinant of immunological aging. The cellular senescence-centric theory of aging proposes a more fundamental and specific role of immune cells in regulating senescent cell (SC) burden in aging tissues that has augmented the notion of senescence immunotherapy. Now, in addition, several emerging studies are suggesting that cellular senescence itself may be prevalent in aging immune cells, and that senescent immune cells exhibiting characteristic markers of cellular senescence, similar to non-leucocyte cells, could be among the key drivers of various facets of physiological aging. The present review integrates the current knowledge related to immunosenescence and cellular senescence in immune cells per se, and aims at providing a cohesive overview of these two phenomena and their significance in immunity and aging. We present evidence and rationalize that understanding the extent and impact of cellular senescence in immune cells vis-à-vis immunosenescence is necessary for truly comprehending the notion of an 'aged immune cell'. In addition, we also discuss the emerging significance of dietary factors such as phytochemicals, probiotic bacteria, fatty acids, and micronutrients as possible modulators of immunosenescence and cellular senescence. Evidence and opportunities related to nutritional bioactive components and immunological aging have been deliberated to augment potential nutrition-oriented immunotherapy during aging.

JOTROL, a Novel Formulation of Resveratrol, Shows Beneficial Effects in the 3xTg-AD Mouse Model

BACKGROUND

Alzheimer's disease (AD) has minimally effective treatments currently. High concentrations of resveratrol, a polyphenol antioxidant found in plants, have been reported to affect several AD-related and neuroprotective genes. To address the low bioavailability of resveratrol, we investigated a novel oral formulation of resveratrol, JOTROL™, that has shown increased pharmacokinetic properties compared to non-formulated resveratrol in animals and in humans.

OBJECTIVE

We hypothesized that equivalent doses of JOTROL, compared to non-formulated resveratrol, would result in greater brain exposure to resveratrol, and more efficacious responses on AD biomarkers.

METHODS

For sub-chronic reversal studies, 15-month-old male triple transgenic (APPSW/PS1M146V/TauP301L; 3xTg-AD) AD mice were treated orally with vehicle or 50 mg/kg JOTROL for 36 days. For prophylactic studies, male and female 3xTg-AD mice were similarly administered vehicle, 50 mg/kg JOTROL, or 50 mg/kg resveratrol for 9 months starting at 4 months of age. A behavioral battery was run, and mRNA and protein from brain and blood were analyzed for changes in AD-related gene and protein expression.

RESULTS

JOTROL displays significantly increased bioavailability over non-formulated resveratrol. Treatment with JOTROL resulted in AD-related gene expression changes (Adam10, Bace1, Bdnf, Psen1) some of which were brain region-dependent and sex-specific, as well as changes in inflammatory gene and cytokine levels.

CONCLUSION

JOTROL may be effective as a prophylaxis and/or treatment for AD through increased expression and/or activation of neuroprotective genes, suppression of pro-inflammatory genes, and regulation of central and peripheral cytokine levels.