Palm Fruit Bioactives modulate human astrocyte activity in vitro altering the cytokine secretome reducing levels of TNFα, RANTES and IP-10

A critical appraisal on the involvement of plant-based extracts as neuroprotective agents (2012-2022): an effort to ease out decision-making process for researchers

The purpose of this review study is to provide a condensed compilation of 164 medicinal plants that have been investigated for their neuroprotective aspects by researchers between the years 2012 and 2022 which also includes a recent update of 2023-2024. After using certain keywords to retrieve the data from SCOPUS, it was manually sorted to eliminate any instances of duplication. The article is streamlined into three major segments. The first segment takes a dig into the current global trend and attempts to decrypt vital information related to plant names, families, plant parts used, and neurological disorders investigated. The second segment of the article makes an attempt to present a comprehensive insight into the various mechanistic pathways through which phytochemicals can intervene to exert neuroprotection. The final segment of the manuscript is a bibliometric appraisal of all researches conducted. The study is based on 256 handpicked articles based on decided inclusion criteria. Illustrative compilation of various pathways citing their activation and deactivation channels are also presented with possible hitting points of various phytochemicals. The present study employed Microsoft Excel 2019 and VOS viewer as data visualisation tools.

Plant based food bioactives: A boon or bane for neurological disorders

Neurological disorders are the foremost occurring diseases across the globe resulting in progressive dysfunction, loss of neuronal structure ultimately cell death. Therefore, attention has been drawn toward the natural resources for the search of neuroprotective agents. Plant-based food bioactives have emerged as potential neuroprotective agents for the treatment of neurodegenerative disorders. This comprehensive review primarily focuses on various plant food bioactive, mechanisms, therapeutic targets, in vitro and in vivo studies in the treatment of neurological disorders to explore whether they are boon or bane for neurological disorders. In addition, the clinical perspective of plant food bioactives in neurological disorders are also highlighted. Scientific evidences point toward the enormous therapeutic efficacy of plant food bioactives in the prevention or treatment of neurological disorders. Nevertheless, identification of food bioactive components accountable for the neuroprotective effects, mechanism, clinical trials, and consolidation of information flow are warranted. Plant food bioactives primarily act by mediating through various pathways including oxidative stress, neuroinflammation, apoptosis, excitotoxicity, specific proteins, mitochondrial dysfunction, and reversing neurodegeneration and can be used for the prevention and therapy of neurodegenerative disorders. In conclusion, the plant based food bioactives are boon for neurological disorders.

Mitochondria-Targeted Human Catalase in the Mouse Longevity MCAT Model Mitigates Head-Tilt Bedrest-Induced Neuro-Inflammation in the Hippocampus

Microgravity (modeled by head-tilt bedrest and hind-limb unloading), experienced during prolonged spaceflight, results in neurological consequences, central nervous system (CNS) dysfunction, and potentially impairment during the performance of critical tasks. Similar pathologies are observed in bedrest, sedentary lifestyle, and muscle disuse on Earth. In our previous study, we saw that head-tilt bedrest together with social isolation upregulated the milieu of pro-inflammatory cytokines in the hippocampus and plasma. These changes were mitigated in a MCAT mouse model overexpressing human catalase in the mitochondria, pointing out the importance of ROS signaling in this stress response. Here, we used a head-tilt model in socially housed mice to tease out the effects of head-tilt bedrest without isolation. In order to find the underlying molecular mechanisms that provoked the cytokine response, we measured CD68, an indicator of microglial activation in the hippocampus, as well as changes in normal in-cage behavior. We hypothesized that hindlimb unloading (HU) will elicit microglial hippocampal activations, which will be mitigated in the MCAT ROS-quenching mice model. Indeed, we saw an elevation of the activated microglia CD68 marker following HU in the hippocampus, and this pathology was mitigated in MCAT mice. Additionally, we identified cytokines in the hippocampus, which had significant positive correlations with CD68 and negative correlations with exploratory behaviors, indicating a link between neuroinflammation and behavioral consequences. Unveiling a correlation between molecular and behavioral changes could reveal a biomarker indicative of these responses and could also result in a potential target for the treatment and prevention of cognitive changes following long space missions and/or muscle disuse on Earth.

Potential neurotoxic activity of diverse molecules released by astrocytes

Astrocytes are the main support cells of the central nervous system. They also participate in neuroimmune reactions. In response to pathological and immune stimuli, astrocytes transform to reactive states characterized by increased release of inflammatory mediators. Some of these molecules are neuroprotective and inflammation resolving while others, including reactive oxygen species (ROS), nitric oxide (NO), matrix metalloproteinase (MMP)- 9, L-glutamate, and tumor necrosis factor α (TNF), are well-established toxins known to cause damage to surrounding cells and tissues. We hypothesized that similar to microglia, the brain immune cells, reactive astrocytes can release a broader set of diverse molecules that are potentially neurotoxic. A literature search was conducted to identify such molecules using the following two criteria: 1) evidence of their expression and secretion by astrocytes and 2) direct neurotoxic action. This review describes 14 structurally diverse molecules as less-established astrocyte neurotoxins, including C-X-C motif chemokine ligand (CXCL)10, CXCL12/CXCL12(5-67), FS-7-associated surface antigen ligand (FasL), macrophage inflammatory protein (MIP)- 2α, TNF-related apoptosis inducing ligand (TRAIL), pro-nerve growth factor (proNGF), pro-brain-derived neurotrophic factor (proBDNF), chondroitin sulfate proteoglycans (CSPGs), cathepsin (Cat)B, group IIA secretory phospholipase A₂ (sPLA₂-IIA), amyloid beta peptides (Aβ), high mobility group box (HMGB)1, ceramides, and lipocalin (LCN)2. For some of these molecules, further studies are required to establish either their direct neurotoxic effects or the full spectrum of stimuli that induce their release by astrocytes. Only limited studies with human-derived astrocytes and neurons are available for most of these potential neurotoxins, which is a knowledge gap that should be addressed in the future. We also summarize available evidence of the role these molecules play in select neuropathologies where reactive astrocytes are a key feature. A comprehensive understanding of the full spectrum of neurotoxins released by reactive astrocytes is key to understanding neuroinflammatory diseases characterized by the adverse activation of these cells and may guide the development of novel treatment strategies.

Effects of polyphenols in aging and neurodegeneration associated with oxidative stress

Aging is defined as the functional loss of tissues and organs over time. This is a biological, irreversible, progressive, and universal process that results from genetic and environmental factors, such as diet, physical activity, smoking, harmful alcohol consumption, and exposure to toxins, among others. Aging is a consequence of molecular and cellular damage built up over time. This damage begins with a gradual decrease in physical and mental capacity, thus increasing the risk of neurodegenerative diseases such as Alzheimer's and Parkinson's disease. Neuronal, functional, and structural damage can be explained by an imbalance among free radicals, reactive oxygen species, reactive nitrogen species, and antioxidants, which finally lead to oxidative stress. Due to the key role of free radicals, reactive oxygen species, and reactive nitrogen species, antioxidant therapy may reduce the oxidative damage associated with neurodegeneration. Exogenous antioxidants are molecules that may help maintain the balance between the formation and elimination of free radicals, thus protecting the cell from their toxicity. Among them, polyphenols are a broad group of secondary plant metabolites with potent antioxidant properties. Here, we review several studies that show the potential role of polyphenol consumption to prevent, or slow down, harmful oxidative processes linked to neurodegenerative disorders.

A Review of Key Sustainability Issues in Malaysian Palm Oil Industry

The palm oil industry has contributed enormously to the economic growth of developing countries in the tropics, including Malaysia. Despite the industry being a development tool for emerging economies, the oil palm crop is inundated with allegations of its unsustainable plantation practices and viewed as environmentally detrimental and socially adverse. These negative perceptions are amplified through anti-palm oil campaigns and protectionist trade regulations in developed countries, particularly in the European Union (EU). This situation, if further exacerbated, could potentially affect the export of palm oil and the industry as a whole. As such, this article provides a critical review of the key sustainability issues faced by the Malaysian palm oil industry as the second biggest exporter of palm oil to the global market. The various insights and the interpretations of sustainability are contested according to the contexts and the interests of the countries involved. Hence, palm oil is constantly exposed to bias masked by non-tariff barriers from consumer countries to protect their domestically produced vegetable oils. This could constrain the commodity competitiveness in the international market. As issues on palm oil sustainability continue to evolve, policymakers at key stakeholder agencies need to devise strategies to manage global disruption in the palm oil trade.

Water-soluble palm fruit extract: composition, biological properties, and molecular mechanisms for health and non-health applications

The oil palm (Elaeis guineensis) fruit is a source of vegetable oil and various phytonutrients. Phytochemical compounds present in palm oil include tocotrienols, carotenoids, phytosterols, squalene, coenzyme Q₁₀, and phospholipids. Being a fruit, the oil palm is also a rich source of water-soluble phytonutrients, including phenolic compounds. Extraction of phytonutrients from the oil palm vegetation liquor of palm oil milling results in a phenolic acid-rich fraction termed Water-Soluble Palm Fruit Extract (WSPFE). Pre-clinical in vitro, ex vivo, and in vivo studies carried out using various biological models have shown that WSPFE has beneficial bioactive properties, while clinical studies in healthy volunteers showed that it is safe for human consumption and confers antioxidant and anti-inflammatory effects. The composition, biological properties, and relevant molecular mechanisms of WSPFE discovered thus far are discussed in the present review, with a view to offer future research perspectives on WSPFE for health and non-health applications.

Three chemotypes of thyme (Thymus vulgaris L.) essential oil and their main compounds affect differently the IL-6 and TNFα cytokine secretions of BV-2 microglia by modulating the NF-κB and C/EBPβ signalling pathways

BACKGROUND

The essential oils possess both antimicrobial and anti-inflammatory effects, therefore they can provide an effective treatment against infections. Essential oils are widely used as supportive ingredients in many diseases, especially in the acute and chronic diseases of the respiratory tract. Neuroinflammation is responsible for several diseases of the central nervous system. Some plant-derived bioactive molecules have been shown to have role in attenuating neuroinflammation by regulating microglia, the immune cells of the CNS.

METHODS

In this study, the anti-inflammatory effect of three chemotypes of thyme essential oil and their main compounds (geraniol, thujanol and linalool) were examined on lipopolysaccharide-induced BV-2 microglia. Three different experimental setups were used, LPS pretreatment, essential oil pretreatment and co-treatments of LPS and essential oils in order to determine whether essential oils are able to prevent inflammation and can decrease it. The concentrations of the secreted tumour necrosis factor α (TNFα) and interleukin-6 (IL-6) proinflammatory cytokines were measured and we analysed by Western blot the activity of the cell signalling pathways, NF-κB and CCAAT-enhancer binding protein β (C/EBPβ) regulating TNFα and IL-6 proinflammatory cytokine expressions in BV-2 cells.

RESULTS

Our results showed definite alterations in the effects of essential oil chemotypes and their main compounds at the different experimental setups. Considering the changes of IL-6 and TNFα secretions the best reduction of inflammatory cytokines could be reached by the pretreatment with the essential oils. In addition, the main compounds exerted better effects than essential oil chemotypes in case of LPS pretreatment. At the essential oil pretreatment experiment, the effect of linalool and geraniol was outstanding but there was no major difference between the actions of chemotypes and standards. Main compounds could be seen to have large inhibitory effects on certain cell signalling components related to the activation of the expression of proinflammatory cytokines.

CONCLUSION

Thyme essential oils are good candidates to use in prevention of neuroinflammation and related neurodegeneration, but the exact ratio of the components has to be selected carefully.

Palm Fruit Bioactive Complex (PFBc), a Source of Polyphenols, Demonstrates Potential Benefits for Inflammaging and Related Cognitive Function

Cognitive function is a key aspect of healthy aging. Inflammation associated with normal aging, also called inflammaging is a primary risk factor for cognitive decline. A diet high in fruits and vegetable and lower in calories, particularly a Mediterranean Diet, may lower the risk of age-related cognitive decline due in part to the associated high intake of antioxidants and polyphenols. A phenolic, Palm Fruit Bioactive complex (PFBc) derived from the extraction process of palm oil from oil palm fruit (Elaeis guineensis), is reported to offset inflammation due to its high antioxidant, especially vitamin E, and polyphenol content. The benefit is thought to be achieved via the influence of antioxidants on gene expression. It is the purpose of this comprehensive review to discuss the etiology, including gene expression, of mild cognitive impairment (MCI) specific to dietary intake of antioxidants and polyphenols and to focus on the potential impact of nutritional interventions specifically PFBc has on MCI. Several in vitro, in vivo and animal studies support multiple benefits of PFBc especially for improving cognitive function via anti-inflammatory and antioxidant mechanisms. While more human studies are needed, those completed thus far support the benefit of consuming PFBc to enhance cognitive function via its anti-inflammatory antioxidant functions.

Chemokines in post-traumatic stress disorder: A network meta-analysis

BACKGROUND

Previous studies on the association between chemokines concentrations and post-traumatic stress disorder (PTSD) yielded inconsistent results. Therefore, the purpose of this network meta-analysis was to summarize these results.

METHODS

The databases of PubMed, Web of Science, Psyc-ARTICLES, Embase and Cochrane Library were searched for relevant articles published not later than January 15, 2020. Then, eligible studies were selected based on predefined study selection criteria. Standardized mean differences (SMDs) with 95% confidence intervals (CIs) were calculated as group differences in chemokines concentrations. Moreover, network meta-analysis was used to rank chemokines effect values according to their respective surface under cumulative ranking curve (SUCRA) probabilities.

FINDINGS

A total of 18 eligible studies that investigated the association between 9 different chemokines and PTSD were identified. They involved 1,510 patients and 2,012 controls. Results of the meta-analysis showed that the concentrations of CCL3, CCL4 and CCL5 in the PTSD patients were significantly higher than that in the controls (SMDs of 4.12, 6.11 and 1.53 respectively). However, although not statistically significant, concentrations of CCL2 tended to be lower in PTSD patients than in the controls (SMD = -0.76); whereas concentrations of CXCL12 tended to be higher in PTSD patients than in the controls (SMD = 0.37). SUCRA probabilities showed that, among all the chemokines studied, the effect of CCL5 was the highest in PTSD patients.

INTERPRETATION

Concentrations of CCL3, CCL4 and CCL5 may be associated with a trauma and/or PTSD. Also, CXCL12 and CCL2 may be the underlying biomarkers for trauma and/or PTSD. Thus, future studies with large population based samples are needed to further assess these associations. In addition, future research should explore possible mechanisms underlying these associations, with the aim to develop new diagnostics for PTSD. PROSPERO CRD42019147703.

The Potential Mechanisms of the Neuroprotective Actions of Oil Palm Phenolics: Implications for Neurodegenerative Diseases

Neurodegenerative diseases (ND) can be characterized by degradation and subsequent loss of neurons. ND has been identified as the leading cause of disability-adjusted life years (DALYs) worldwide and is associated with various risk factors such as ageing, certain genetic polymorphisms, inflammation, immune and metabolic conditions that may induce elevated reactive oxygen species (ROS) release and subsequent oxidative stress. Presently, no specific cure or prevention is available for ND patients; the symptoms can be only alleviated via drug treatment or surgery. The existing pharmacological treatments are only available for partial treatment of the symptoms. A natural product known as oil palm phenolics (OPP), which is high in antioxidant, could become a potential supplementary antioxidant for neurodegenerative health. OPP is a water-soluble extract from palm fruit that demonstrated medicinal properties including anti-tumor, anti-diabetic and neuroprotective effects. In this review, OPP was proposed for its neuroprotective effects via several mechanisms including antioxidant and anti-inflammatory properties. Besides, OPP has been found to modulate the genes involved in neurotrophic activity. The evidence and proposed mechanism of OPP on the neuroprotective health may provide a comprehensive natural medicine approach to alleviate the symptoms of neurodegenerative diseases.

Characterization of Astrocytic Response after Experiencing Cavitation In Vitro

When a traumatic brain injury (TBI) occurs, low-pressure regions inside the skull can cause vapor contents in the cerebral spinal fluid (CSF) to expand and collapse, a phenomenon known as cavitation. When these microbubbles (MBs) collapse, shock waves are radiated outward and are known to damage surrounding materials in other applications, like the steel foundation of boat propellers, so it is alarming to realize the damage that cavitation inflicts on vulnerable brain tissue. Using cell-laden microfibers, the longitudinal morphological response that mouse astrocytes have to surrounding cavitation in vitro is visually analyzed. Astrocytic damage is evident immediately after cavitation when compared to a control sample, as their processes retract. Forty-eight hours later, the astrocytes appeared to spread across the fibers, as normal. This study also analyzes the gene expression changes that occur post-cavitation via quantitative polymerase chain reaction (qPCR) methods. After cavitation a number of pro-inflammatory genes are upregulated, including TNFα, IL-1β, C1q, Serping1, NOS1, IL-6, and JMJD3. Taken together, these results confirm that surrounding cavitation is detrimental to astrocytic function, and yield opportunities to further the understanding of how protective headgear can minimize or eliminate the occurrence of cavitation.

Lemon essential oil ameliorates age-associated cognitive dysfunction via modulating hippocampal synaptic density and inhibiting acetylcholinesterase

The lemon essential oil (LEO), extracted from the fruit of lemon, has been used to treat multiple pathological diseases, such as diabetes, inflammation, cardiovascular diseases, depression and hepatobiliary dysfunction. The study was designed to study the effects of LEO on cognitive dysfunction induced by Alzheimer’s disease (AD). We used APP/PS1 double transgene (APP/PS1) AD mice in the experiment; these mice exhibit significant deficits in synaptic density and hippocampal-dependent spatial related memory. The effects of LEO on learning and memory were examined using the Morris Water Maze (MWM) test, Novel object recognition test, and correlative indicators, including a neurotransmitter (acetylcholinesterase, AChE), a nerve growth factor (brain-derived neurotrophic factor, BDNF), a postsynaptic marker (PSD95), and presynaptic markers (synapsin-1, and synaptophysin), in APP/PS1 mice. Histopathology was performed to estimate the effects of LEO on AD mice. A significantly lowered brain AChE depression in APP/PS1 and wild-type C57BL/6L (WT) mice. PSD95/ Synaptophysin, the index of synaptic density, was noticeably improved in histopathologic changes. Hence, it can be summarized that memory-enhancing activity might be associated with a reduction in the AChE levels and is elevated by BDNF, PSD95, and synaptophysin through enhancing synaptic plasticity.

Palm Fruit Bioactives augment expression of Tyrosine Hydroxylase in the Nile Grass Rat basal ganglia and alter the colonic microbiome

Tyrosine hydroxylase (TH) catalyzes the hydroxylation of L-tyrosine to L-DOPA. This is the rate-limiting step in the biosynthesis of the catecholamines - dopamine (DA), norepinephrine (NE), and epinephrine (EP). Catecholamines (CA) play a key role as neurotransmitters and hormones. Aberrant levels of CA are associated with multiple medical conditions, including Parkinson's disease. Palm Fruit Bioactives (PFB) significantly increased the levels of tyrosine hydroxylase in the brain of the Nile Grass rat (NGR), a novel and potentially significant finding, unique to PFB among known botanical sources. Increases were most pronounced in the basal ganglia, including the caudate-putamen, striatum and substantia nigra. The NGR represents an animal model of diet-induced Type 2 Diabetes Mellitus (T2DM), exhibiting hyperglycemia, hyperinsulinemia, and insulin resistance associated with hyperphagia and accelerated postweaning weight gain induced by a high-carbohydrate diet (hiCHO). The PFB-induced increase of TH in the basal ganglia of the NGR was documented by immuno-histochemical staining (IHC). This increase in TH occurred equally in both diabetes-susceptible and diabetes-resistant NGR fed a hiCHO. PFB also stimulated growth of the colon microbiota evidenced by an increase in cecal weight and altered microbiome.  The metabolites of colon microbiota, e.g. short-chain fatty acids, may influence the brain and behavior significantly.

Cytochrome c can be released into extracellular space and modulate functions of human astrocytes in a toll-like receptor 4-dependent manner

BACKGROUND

Chronic activation of glial cells contributes to neurodegenerative diseases. Cytochrome c (CytC) is a soluble mitochondrial protein that can act as a damage-associated molecular pattern (DAMP) when released into the extracellular space from damaged cells. CytC causes immune activation of microglia in a toll-like receptor (TLR) 4-dependent manner. The effects of extracellular CytC on astrocytes are unknown. Astrocytes, which are the most abundant glial cell type in the brain, express TLR 4 and secrete inflammatory mediators; therefore, we hypothesized that extracellular CytC can interact with the TLR 4 of astrocytes inducing their release of inflammatory molecules and cytotoxins.

METHOD

Experiments were conducted using primary human astrocytes, U118 MG human astrocytic cells, BV-2 murine microglia, and SH-SY5Y human neuronal cells.

RESULTS

Extracellularly applied CytC increased the secretion of interleukin (IL)-1β, granulocyte-macrophage colony stimulating factor (GM-CSF) and IL-12 p70 by cultured primary human astrocytes. Anti-TLR 4 antibodies blocked the CytC-induced secretion of IL-1β and GM-CSF by astrocytes. Supernatants from CytC-activated astrocytes were toxic to human SH-SY5Y neuronal cells. We also demonstrated CytC release from damaged glial cells by measuring CytC in the supernatants of BV-2 microglia after their exposure to cytotoxic concentrations of staurosporine, amyloid-β peptides (Aβ42) and tumor necrosis factor-α.

CONCLUSION

CytC can be released into the extracellular space from damaged glial cells causing immune activation of astrocytes in a TLR 4-dependent manner.

GENERAL SIGNIFICANCE

Astrocyte activation by CytC may contribute to neuroinflammation and neuronal death in neurodegenerative diseases. Astrocyte TLR 4 could be a potential therapeutic target in these diseases.