Resveratrol targeting tau proteins, amyloid-beta aggregations, and their adverse effects: An updated review

Study on the relationship between berry, grape, red wine consumption and cognitive impairment in middle-aged and elderly people in China

Introduction

Some evidence suggests that fruit and alcohol consumption may be related to cognitive impairment.

Methods

This study conducted a cross-sectional study on the "correlation between eating habits and cognitive function of the middle-aged and elderly population in China." The purpose of this study is to explore the relationship between fruit consumption, drinking habits and cognitive impairment in Chinese people over 50 years old.

Results

The results show that the protective factors of cognitive impairment are the preference for berries and the daily intake of 100-200 grams grapes in Chinese middle-aged and elderly people with objective cognitive unimpaired. The habit of drinking red wine is a protective factor for cognitive impairment in Chinese middle-aged and elderly people with mild cognitive impairment (MCI). However, this study did not find the relationship between white wine, beer, yellow rice wine, liquor and cognitive impairment.

Discussion

Therefore, we believe that berries, grapes and red wine consumption can protect the cognitive function of the middle-aged and elderly people in China, and the protective function is related to the basic cognitive state.

The Inhibition Effect of Epigallocatechin-3-Gallate on the Co-Aggregation of Amyloid-β and Human Islet Amyloid Polypeptide Revealed by Replica Exchange Molecular Dynamics Simulations

Alzheimer's disease and Type 2 diabetes are two epidemiologically linked diseases which are closely associated with the misfolding and aggregation of amyloid proteins amyloid-β (Aβ) and human islet amyloid polypeptide (hIAPP), respectively. The co-aggregation of the two amyloid proteins is regarded as the fundamental molecular mechanism underlying their pathological association. The green tea extract epigallocatechin-3-gallate (EGCG) has been extensively demonstrated to inhibit the amyloid aggregation of Aβ and hIAPP proteins. However, its potential role in amyloid co-aggregation has not been thoroughly investigated. In this study, we employed the enhanced-sampling replica exchange molecular dynamics simulation (REMD) method to investigate the effect of EGCG on the co-aggregation of Aβ and hIAPP. We found that EGCG molecules substantially diminish the β-sheet structures within the amyloid core regions of Aβ and hIAPP in their co-aggregates. Through hydrogen-bond, π-π and cation-π interactions targeting polar and aromatic residues of Aβ and hIAPP, EGCG effectively attenuates both inter-chain and intra-chain interactions within the co-aggregates. All these findings indicated that EGCG can effectively inhibit the co-aggregation of Aβ and hIAPP. Our study expands the potential applications of EGCG as an anti-amyloidosis agent and provides therapeutic options for the pathological association of amyloid misfolding disorders.

Modulation of Tau Pathology in Alzheimer's Disease by Dietary Bioactive Compounds

Tau is a microtubule-associated protein essential for microtubule assembly and stability in neurons. The abnormal intracellular accumulation of tau aggregates is a major characteristic of brains from patients with Alzheimer's disease (AD) and other tauopathies. In AD, the presence of neurofibrillary tangles (NFTs), which is composed of hyperphosphorylated tau protein, is positively correlated with the severity of the cognitive decline. Evidence suggests that the accumulation and aggregation of tau cause synaptic dysfunction and neuronal degeneration. Thus, the prevention of abnormal tau phosphorylation and elimination of tau aggregates have been proposed as therapeutic strategies for AD. However, currently tau-targeting therapies for AD and other tauopathies are limited. A number of dietary bioactive compounds have been found to modulate the posttranslational modifications of tau, including phosphorylation, small ubiquitin-like modifier (SUMO) mediated modification (SUMOylation) and acetylation, as well as inhibit tau aggregation and/or promote tau degradation. The advantages of using these dietary components over synthetic substances in AD prevention and intervention are their safety and accessibility. This review summarizes the mechanisms leading to tau pathology in AD and highlights the effects of bioactive compounds on the hyperphosphorylation, aggregation and clearance of tau protein. The potential of using these bioactive compounds for AD prevention and intervention is also discussed.

Effects of preventive interventions on neuroimaging biomarkers in subjects at-risk to develop Alzheimer's disease: A systematic review

Alzheimer's Disease (AD) is a multifactorial and complex neurodegenerative disorder. Some modifiable risk factors have been associated with an increased risk of appearance of the disease and/or cognitive decline. Preventive clinical trials aiming at reducing one or combined risk factors have been implemented and their potential effects assessed on cognitive trajectories and on AD biomarkers. However, the effect of interventions on surrogate markers, in particular imaging biomarkers, remains poorly understood. We conducted a review of the literature and analyzed 43 interventional studies that included physical exercise, nutrition, cognitive training or multidomain interventions, and assessed various brain imaging biomarkers, to determine the effects of preventive interventions on imaging biomarkers for subjects at-risk to develop AD. Deciphering the global and regional brain effect of each and combined interventions will help to better understand the interplay relationship between multimodal interventions, cognition, surrogate brain markers, and to better design primary and secondary outcomes for future preventive clinical trials. Those studies were pondered using generally-admitted quality criteria to reveal that interventions may affect the brain of patients with cognitive impairment rather than those without cognitive impairment thus indicating that particular care should be taken when selecting individuals for interventions. Additionally, a majority of the studies concurred on the effect of the interventions and particularly onto the frontal brain areas.

Resveratrol in breast cancer treatment: from cellular effects to molecular mechanisms of action

Breast cancer (BC) is one of the most common cancers in females and is responsible for the highest cancer-related deaths following lung cancer. The complex tumor microenvironment and the aggressive behavior, heterogenous nature, high proliferation rate, and ability to resist treatment are the most well-known features of BC. Accordingly, it is critical to find an effective therapeutic agent to overcome these deleterious features of BC. Resveratrol (RES) is a polyphenol and can be found in common foods, such as pistachios, peanuts, bilberries, blueberries, and grapes. It has been used as a therapeutic agent for various diseases, such as diabetes, cardiovascular diseases, inflammation, and cancer. The anticancer mechanisms of RES in regard to breast cancer include the inhibition of cell proliferation, and reduction of cell viability, invasion, and metastasis. In addition, the synergistic effects of RES in combination with other chemotherapeutic agents, such as docetaxel, paclitaxel, cisplatin, and/or doxorubicin may contribute to enhancing the anticancer properties of RES on BC cells. Although, it demonstrates promising therapeutic features, the low water solubility of RES limits its use, suggesting the use of delivery systems to improve its bioavailability. Several types of nano drug delivery systems have therefore been introduced as good candidates for RES delivery. Due to RES's promising potential as a chemopreventive and chemotherapeutic agent for BC, this review aims to explore the anticancer mechanisms of RES using the most up to date research and addresses the effects of using nanomaterials as delivery systems to improve the anticancer properties of RES.

Oxidative Stress in Tauopathies: From Cause to Therapy

Oxidative stress (OS) is the result of an imbalance between the production of reactive oxygen species (ROS) and the antioxidant capacity of cells. Due to its high oxygen demand, the human brain is highly susceptible to OS and, thus, it is not a surprise that OS has emerged as an essential component of the pathophysiology of several neurodegenerative diseases, including tauopathies. Tauopathies are a heterogeneous group of age-related neurodegenerative disorders characterized by the deposition of abnormal tau protein in the affected neurons. With the worldwide population aging, the prevalence of tauopathies is increasing, but effective therapies have not yet been developed. Since OS seems to play a key role in tauopathies, it has been proposed that the use of antioxidants might be beneficial for tau-related neurodegenerative diseases. Although antioxidant therapies looked promising in preclinical studies performed in cellular and animal models, the antioxidant clinical trials performed in tauopathy patients have been disappointing. To develop effective antioxidant therapies, the molecular mechanisms underlying OS in tauopathies should be completely understood. Here, we review the link between OS and tauopathies, emphasizing the causes of OS in these diseases and the role of OS in tau pathogenesis. We also summarize the antioxidant therapies proposed as a potential treatment for tauopathies and discuss why they have not been completely translated to clinical trials. This review aims to provide an integrated perspective of the role of OS and antioxidant therapies in tauopathies. In doing so, we hope to enable a more comprehensive understanding of OS in tauopathies that will positively impact future studies.

Exosomes as Promising Nanostructures in Diabetes Mellitus: From Insulin Sensitivity to Ameliorating Diabetic Complications

Diabetes mellitus (DM) is among the chronic metabolic disorders that its incidence rate has shown an increase in developed and wealthy countries due to lifestyle and obesity. The treatment of DM has always been of interest, and significant effort has been made in this field. Exosomes belong to extracellular vesicles with nanosized features (30-150 nm) that are involved in cell-to-cell communication and preserving homeostasis. The function of exosomes is different based on their cargo, and they may contain lipids, proteins, and nucleic acids. The present review focuses on the application of exosomes in the treatment of DM; both glucose and lipid levels are significantly affected by exosomes, and these nanostructures enhance lipid metabolism and decrease its deposition. Furthermore, exosomes promote glucose metabolism and affect the level of glycolytic enzymes and glucose transporters in DM. Type I DM results from the destruction of β cells in the pancreas, and exosomes can be employed to ameliorate apoptosis and endoplasmic reticulum (ER) stress in these cells. The exosomes have dual functions in mediating insulin resistance/sensitivity, and M1 macrophage-derived exosomes inhibit insulin secretion. The exosomes may contain miRNAs, and by transferring among cells, they can regulate various molecular pathways such as AMPK, PI3K/Akt, and β-catenin to affect DM progression. Noteworthy, exosomes are present in different body fluids such as blood circulation, and they can be employed as biomarkers for the diagnosis of diabetic patients. Future studies should focus on engineering exosomes derived from sources such as mesenchymal stem cells to treat DM as a novel strategy.

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.

Oligomer-Targeting Prevention of Neurodegenerative Dementia by Intranasal Rifampicin and Resveratrol Combination - A Preclinical Study in Model Mice

Amyloidogenic protein oligomers are thought to play an important role in the pathogenesis of neurodegenerative dementia, including Alzheimer’s disease, frontotemporal dementia, and dementia with Lewy bodies. Previously we demonstrated that oral or intranasal rifampicin improved the cognition of APP-, tau-, and α-synuclein-transgenic mice by reducing the amount of Aβ, tau, and α-synuclein oligomers in the brain. In the present study, to explore more effective and safer medications for dementia, we tested the drug combination of rifampicin and resveratrol, which is a multifunctional natural polyphenol with the potential to antagonize the adverse effects of rifampicin. The mixture was intranasally administered to APP-, tau-, and α-synuclein-transgenic mice, and their memory and oligomer-related pathologies were evaluated. Compared with rifampicin and resveratrol alone, the combinatorial medicine significantly improved mouse cognition, reduced amyloid oligomer accumulation, and recovered synaptophysin levels in the hippocampus. The plasma levels of liver enzymes, which reflect hepatic injury and normally increase by rifampicin treatment, remained normal by the combination treatment. Notably, resveratrol alone and the combinatorial medicine, but not rifampicin alone, enhanced the levels of brain-derived neurotrophic factor (BDNF) and its precursor, pro-BDNF, in the hippocampus. Furthermore, the combination showed a synergistic effect in ameliorating mouse cognition. These results show the advantages of this combinatorial medicine with regards to safety and effectiveness over single-drug rifampicin. Our findings may provide a feasible means for the prevention of neurodegenerative dementia that targets toxic oligomers.

Targeting Cancer Stem Cells by Dietary Agents: An Important Therapeutic Strategy against Human Malignancies

As a multifactorial disease, treatment of cancer depends on understanding unique mechanisms involved in its progression. The cancer stem cells (CSCs) are responsible for tumor stemness and by enhancing colony formation, proliferation as well as metastasis, and these cells can also mediate resistance to therapy. Furthermore, the presence of CSCs leads to cancer recurrence and therefore their complete eradication can have immense therapeutic benefits. The present review focuses on targeting CSCs by natural products in cancer therapy. The growth and colony formation capacities of CSCs have been reported can be attenuated by the dietary agents. These compounds can induce apoptosis in CSCs and reduce tumor migration and invasion via EMT inhibition. A variety of molecular pathways including STAT3, Wnt/β-catenin, Sonic Hedgehog, Gli1 and NF-κB undergo down-regulation by dietary agents in suppressing CSC features. Upon exposure to natural agents, a significant decrease occurs in levels of CSC markers including CD44, CD133, ALDH1, Oct4 and Nanog to impair cancer stemness. Furthermore, CSC suppression by dietary agents can enhance sensitivity of tumors to chemotherapy and radiotherapy. In addition to in vitro studies, as well as experiments on the different preclinical models have shown capacity of natural products in suppressing cancer stemness. Furthermore, use of nanostructures for improving therapeutic impact of dietary agents is recommended to rapidly translate preclinical findings for clinical use.

Boosting immune system against cancer by resveratrol

Modulation of the immune system is a critical part of anticancer therapies including immunotherapy, chemotherapy, and radiotherapy. The aim of immunomodulation in cancer therapy is boosting immune system cells including CD8+ T lymphocytes and natural killer (NK) cells, as well as suppression of immunosuppressive responses by macrophages and regulatory T cells (Tregs). Usually, using single or dual modality can induce immune system responses against cancer. However, immunosuppressive responses attenuate antitumor immunity following cancer therapy. Using some agents to boost immune system's function against cancer can increase therapeutic efficiency of anticancer therapy. Resveratrol, as a natural agent, has shown ability to modulate the immune system to potentiate antitumor immunity. Resveratrol has been shown to induce the release of anticancer cytokines such as IFN-γ and TNF-α and also inhibits the release of TGF-β. It also can stimulate the polarization of CD4+ T cells and macrophages toward anticancer cells and reduce infiltration and polarization of immunosuppressive cells. Furthermore, resveratrol can sensitize cancer cells to the released dead signals by anticancer immune cells. This review explains how resveratrol can boost the immune system against cancer via modulation of immune cell responses within tumor.

Nutraceuticals and their Derived Nano-formulations for the Prevention and Treatment of Alzheimer's disease

Alzheimer's disease is one of the common chronic neurological disorders and associated with cognitive dysfunction, depression and progressive dementia. Presence of β-amyloid or senile plaques, hyper-phosphorylated tau proteins, neurofibrillary tangle, oxidative-nitrative stress, mitochondrial dysfunction, endoplasmic reticulum stress, neuroinflammation and derailed neurotransmitter status are the hallmark of AD. Currently, donepezil, memantine, rivastigmine and galantamine are approved by the FDA for symptomatic management. It is well-known that these approved drugs only exert symptomatic relief and possess poor patient-compliance. Additionally, various published evidence shows the neuroprotective potential of various nutraceuticals via their antioxidant, anti-inflammatory and anti-apoptotic effects in the preclinical and clinical studies. These nutraceuticals possess a significant neuroprotective potential and hence, can be a future pharmacotherapeutic for the management and treatment of AD. However, nutraceutical suffers from certain major limitations such as poor solubility, low bioavailability, low stability, fast hepatic-metabolism and larger particle size. These pharmacokinetic attributes restrict their entry into the brain via the blood-brain barrier. Therefore, to over such issues, various nanoformulation of nutraceuticals was developed, that allows their effective delivery into brain owning to reduced particle size, increased lipophilicity increased bioavailability and avoidance of fast hepatic metabolism. Thus, in this review, we have discussed the etiology of AD, focused on the pharmacotherapeutics of nutraceuticals with preclinical and clinical evidence, discussed pharmaceutical limitation and regulatory aspects of nutraceuticals to ensure safety and efficacy. We further explored the latitude of various nanoformulation of nutraceuticals as a novel approach to overcome the existing pharmaceutical limitation and for effective delivery into the brain.

[Network pharmacology-based study of the therapeutic mechanism of resveratrol for Alzheimer's disease]

OBJECTIVE

To investigate the therapeutic mechanism of resveratrol (RES) for Alzheimer's disease (AD) in light of network pharmacology.

METHODS

We searched PubChem, BATMAN-TCM, Genecards, AD, TTD, String 11.0, AlzData, SwissTargetPrediction, Metascape and other databases for the therapeutic targets of RES and human AD-related targets. The intersection was determined using Venny 2.1 to obtain the therapeutic targets of RES for AD. The protein-protein interaction (PPI) network was constructed, the gene ontology (GO) was enriched and the Kyoto Encyclopedia of Genes and Genomes pathway (KEGG pathway) were analyzed. Cytoscape 3.7.1 software was used to construct a target-signaling pathway network of RES in the treatment of AD. Molecular docking verification was carried out on SwissDock (http://www.swissdock.ch/docking). We examined a 293Tau cell model of AD for changes in protein levels of pS396, pS199, Tau5, CDK5, glycogen synthase kinase 3β (GSK3β) and p-GSK3β in response to RES treatment using Western blotting.

RESULTS

We obtained 182 targets of RES, 525 targets related to AD, and 36 targets of RES for AD treatment, among which 34.6% of the targets were protein-modifying enzymes, 27.7% were metabolite invertase, 13.8% were gene-specific transcriptional regulators, and 10.3% were transporters. The core key targets of RES in the treatment of AD included INS, APP, ESR1, MMP9, IGF1R, CACNA1C, MAPT (microtubule- associated protein Tau), MMP2, TGFB1 and GSK3B. Enrichment analysis of GO biological process suggested that the biological function of RES in AD treatment mainly involved the response to β-amyloid protein, positive regulation of transferase activity, the transmembrane receptor protein tyrosine kinase signaling pathway, regulation of behavior, learning or memory, aging, and transmembrane transport. KEGG pathway enrichment analysis showed that the most significantly enriched signaling pathways were AD pathway, PI3K-AKT signaling pathway, cGMP-PKG signaling pathway, and MAPK signaling pathway. Molecular docking results showed that RES had strong binding with ESR1, GSK3B, MMP9, IGF1R, APP and INS. In the cell model of AD, treatment with 50 μmol/L RES for 12 h significantly reduced the levels of pS396 and pS199 by regulating CDK5 and GSK3β activity (P < 0.001).

CONCLUSIONS

RES produces therapeutic effects on AD by acting on multiple targets and affecting multiple signaling pathways and improves AD-associated pathologies via a direct action on Aβ and Tau pathological processes.

Crystal structure of death-associated protein kinase 1 in complex with the dietary compound resveratrol

Death-associated protein kinase 1 (DAPK1) is a large multidomain protein with an N-terminal serine/threonine protein kinase domain. DAPK1 is considered to be a promising molecular target for the treatment of Alzheimer's disease (AD). In the present study, the inhibitory potency of resveratrol (RSV), a dietary polyphenol found in red wine, against the catalytic activity of DAPK1 was investigated. Kinetic and fluorescent probe competitive binding analyses revealed that RSV directly inhibited the catalytic activity of DAPK1 by binding to the ATP-binding site. Crystallographic analysis of DAPK1 in complex with RSV revealed that the A-ring of RSV occupied the nucleobase-binding position. Determination of the binding mode provided a structural basis for the design of more potent DAPK1 inhibitors. In conclusion, the data here clearly show that RSV is an ATP-competitive inhibitor of DAPK1, encouraging speculation that RSV may be useful for the development of AD inhibitors.