Citrus flavonoid 3,5,6,7,8,3',4'-heptamethoxyflavone induces BDNF via cAMP/ERK/CREB signaling and reduces phosphodiesterase activity in C6 cells

Polyphenols: Natural Food-Grade Biomolecules for the Treatment of Nervous System Diseases from a Multi-Target Perspective

Polyphenols are the most prevalent naturally occurring phytochemicals in the human diet and range in complexity from simple molecules to high-molecular-weight polymers. They have a broad range of chemical structures and are generally categorized as "neuroprotective", "anti-inflammatory", and "antioxidant" given their main function of halting disease onset and promoting health. Research has shown that some polyphenols and their metabolites can penetrate the blood-brain barrier and hence increase neuroprotective signaling and neurohormonal effects to provide anti-inflammatory and antioxidant effects. Therefore, multi-targeted modulation of polyphenols may prevent the progression of neuropsychiatric disorders and provide a new practical therapeutic strategy for difficult-to-treat neuropsychiatric disorders. Therefore, multi-target modulation of polyphenols has the potential to prevent the progression of neuropsychiatric disorders and provide a new practical therapeutic strategy for such nervous system diseases. Herein, we review the therapeutic benefits of polyphenols on autism-spectrum disorders, anxiety disorders, depression, and sleep disorders, along with in vitro and ex vivo experimental and clinical trials. Although their methods of action are still under investigation, polyphenols are still seldom employed directly as therapeutic agents for nervous system disorders. Comprehensive mechanistic investigations and large-scale multicenter randomized controlled trials are required to properly evaluate the safety, effectiveness, and side effects of polyphenols.

Therapeutic implications of phosphorylation- and dephosphorylation-dependent factors of cAMP-response element-binding protein (CREB) in neurodegeneration

Neurodegeneration is a condition of the central nervous system (CNS) characterized by loss of neural structures and function. The most common neurodegenerative disorders (NDDs) include Alzheimer's disease (AD), Huntington's disease (HD), amyotrophic lateral sclerosis (ALS), Parkinson's disease (PD), multiple sclerosis (MS), motor neuron disorders, psychological disorders, dementia with vascular dementia (VaD), Lewy body dementia (DLB), epilepsy, cerebral ischemia, mental illness, and behavioral disorders. CREB (cAMP-response element-binding protein) represent a nuclear protein that regulates gene transcriptional activity. The primary focus of the review pertains to the exploration of CREB expression and activation within the context of neurodegenerative diseases, specifically in relation to the phosphorylation and dephosphorylation events that occur within the CREB signaling pathway under normal physiological conditions. The findings mentioned have contributed to the elucidation of the regulatory mechanisms governing CREB activity. Additionally, they have provided valuable insights into the potential mediation of diverse biological processes, such as memory consolidation and neuroprotective effects, by various related studies. The promotion of synaptic plasticity and neurodevelopment in the central nervous system through the targeting of CREB proteins has the potential to contribute to the prevention or delay of the onset of neurodegenerative disorders. Multiple drugs have been found to initiate downstream signaling pathways, leading to neuroprotective advantages in both animal model studies and clinical trials. The clinical importance of the cAMP-response element-binding protein (CREB) is examined in this article, encompassing its utility as both a predictive/prognostic marker and a target for therapeutic interventions.

Rolipram Ameliorates Memory Deficits and Depression-Like Behavior in APP/PS1/tau Triple Transgenic Mice: Involvement of Neuroinflammation and Apoptosis via cAMP Signaling

BACKGROUND

Alzheimer disease (AD) and depression often cooccur, and inhibition of phosphodiesterase-4 (PDE4) has been shown to ameliorate neurodegenerative illness. Therefore, we explored whether PDE4 inhibitor rolipram might also improve the symptoms of comorbid AD and depression.

METHODS

APP/PS1/tau mice (10 months old) were treated with or without daily i.p. injections of rolipram for 10 days. The animal groups were compared in behavioral tests related to learning, memory, anxiety, and depression. Neurochemical measures were conducted to explore the underlying mechanism of rolipram.

RESULTS

Rolipram attenuated cognitive decline as well as anxiety- and depression-like behaviors. These benefits were attributed at least partly to the downregulation of amyloid-β, Amyloid precursor protein (APP), and Presenilin 1 (PS1); lower tau phosphorylation; greater neuronal survival; and normalized glial cell function following rolipram treatment. In addition, rolipram upregulated B-cell lymphoma-2 (Bcl-2) and downregulated Bcl-2-associated X protein (Bax) to reduce apoptosis; it also downregulated interleukin-1β, interleukin-6, and tumor necrosis factor-α to restrain neuroinflammation. Furthermore, rolipram increased cAMP, PKA, 26S proteasome, EPAC2, and phosphorylation of ERK1/2 while decreasing EPAC1.

CONCLUSIONS

Rolipram may mitigate cognitive deficits and depression-like behavior by reducing amyloid-β pathology, tau phosphorylation, neuroinflammation, and apoptosis. These effects may be mediated by stimulating cAMP/PKA/26S and cAMP/exchange protein directly activated by cAMP (EPAC)/ERK signaling pathways. This study suggests that PDE4 inhibitor rolipram can be an effective target for treatment of comorbid AD and depression.

Effects of Citrus kawachiensis Peel in Frailty-like Model Mice Induced by Low Protein Nutrition Disorders

"Frailty" caused by a decline in physiological reserve capacity, chronic inflammation, and oxidative stress in the elderly has recently become a major social issue. The present study examined the effects of the peel of Citrus kawachiensis (CK), which exhibits anti-inflammatory, antioxidant, and pro-neurogenesis activities in frailty-like model mice. Male C57BL/6 mice (15 weeks old) were fed an 18% protein diet (CON), a 2.5% protein diet (PM), and PM mixed with 1% dried CK peel powder for approximately 1 month. Mice were euthanized 2 or 8 days after a single intraperitoneal administration of lipopolysaccharide (LPS) and tissues were dissected. Among peripheral tissues, muscle weight, liver weight, and blood glucose levels were significantly higher in the PM-LPS-CK group than in the PM-LPS group. In the behavioral analysis, locomotive activity was significantly lower in the PM-LPS group than in the PM group. The reduction in locomotive activity in the PM-LPS-CK group was significantly smaller than that in the PM-LPS group. The quantification of microglia in the hippocampal stratum lacunosum-moleculare revealed that increases in the PM-LPS group were significantly suppressed by the dried CK peel powder. Furthermore, the quantification of synaptic vesicle membrane proteins in the hippocampal CA3 region showed down-regulated expression in the PM-LPS group, which was significantly ameliorated by the administration of the dried CK peel powder. Collectively, these results suggest that CK inhibits inflammation and oxidative stress induced by PM and LPS in the central nervous system and peripheral tissue. Therefore, C. kawachiensis is highly effective against "frailty".

Zebrafish: A Model Deciphering the Impact of Flavonoids on Neurodegenerative Disorders

Over the past century, advances in biotechnology, biochemistry, and pharmacognosy have spotlighted flavonoids, polyphenolic secondary metabolites that have the ability to modulate many pathways involved in various biological mechanisms, including those involved in neuronal plasticity, learning, and memory. Moreover, flavonoids are known to impact the biological processes involved in developing neurodegenerative diseases, namely oxidative stress, neuroinflammation, and mitochondrial dysfunction. Thus, several flavonoids could be used as adjuvants to prevent and counteract neurodegenerative disorders such as Alzheimer's and Parkinson's diseases. Zebrafish is an interesting model organism that can offer new opportunities to study the beneficial effects of flavonoids on neurodegenerative diseases. Indeed, the high genome homology of 70% to humans, the brain organization largely similar to the human brain as well as the similar neuroanatomical and neurochemical processes, and the high neurogenic activity maintained in the adult brain makes zebrafish a valuable model for the study of human neurodegenerative diseases and deciphering the impact of flavonoids on those disorders.

The Therapeutic Potential of Naturally Occurring Peptides in Counteracting SH-SY5Y Cells Injury

Peptides have revealed a large range of biological activities with high selectivity and efficiency for the development of new drugs, including neuroprotective agents. Therefore, this work investigates the neuroprotective properties of naturally occurring peptides, endomorphin-1 (EM-1), endomorphin-2 (EM-2), rubiscolin-5 (R-5), and rubiscolin-6 (R-6). We aimed at answering the question of whether well-known opioid peptides can counteract cell injury in a common in vitro model of Parkinson’s disease (PD). Antioxidant activity of these four peptides was evaluated by the 2-diphenyl-1-picrylhydrazyl radical (DPPH) scavenging activity, oxygen radical absorbance capacity (ORAC), and ferric-reducing antioxidant power (FRAP) assays, while neuroprotective effects were assessed in a neurotoxic model induced by 6-hydroxydopamine (6-OHDA) in a human neuroblastoma cell line (SH-SY5Y). The mechanisms associated with neuroprotection were investigated by the determination of mitochondrial membrane potential (MMP), reactive oxygen species (ROS) production, and Caspase-3 activity. Among the tested peptides, endomorphins significantly prevented neuronal death induced by 6-OHDA treatment, decreasing MMP (EM-1) or Caspase-3 activity (EM-2). Meanwhile, R-6 showed antioxidant potential by FRAP assay and exhibited the highest capacity to recover the neurotoxicity induced by 6-OHDA via attenuation of ROS levels and mitochondrial dysfunction. Generally, we hypothesize that peptides’ ability to suppress the toxic effect induced by 6-OHDA may be mediated by different cellular mechanisms. The protective effect caused by endomorphins results in an antiapoptotic effect (mitochondrial protection and decrease in Caspase-3 activity), while R-6 potency to increase a cell’s viability seems to be mediated by reducing oxidative stress. Our results may provide new insight into neurodegeneration and support the short peptides as a potent drug candidate to treat PD. However, further studies should be conducted on the detailed mechanisms of how tested peptides could suppress neuronal injuries.

Activation of Extracellular Signal-Regulated Kinase 2 and cAMP Response Element-Binding Protein in Cultured Neurons by the Macrocyclic Ellagitannin Oenothein B

(1) Background: The findings of our recent in vivo study indicated that the oral administration of oenothein B, a unique macrocyclic ellagitannin, activated extracellular signal-regulated kinase (ERK) 2 and cAMP response element-binding protein (CREB) in the mouse brain. A large hydrophilic oenothein B is unable to reach the brain, suggesting that any metabolite(s) of oenothein B might function in the brain. (2) Results: The addition of oenothein B to the culture medium of rat cortical neurons induced the prompt and significant activation of ERK2 and CREB. (3) Conclusions: The activation of ERK2 and CREB is crucial for synaptic transmission and learning/memory formation in the brain. The present results suggest oenothein B exerts neurotrophic/neuroprotective effects in the brain through the modulation of neuronal signaling pathways, if it reaches the brain.

The Mechanism Study of Common Flavonoids on Antiglioma Based on Network Pharmacology and Molecular Docking

BACKGROUND

Glioma is the most common primary intracranial tumor in adult patients. Among them, glioblastoma is a highly malignant one with a poor prognosis. Flavonoids are a class of phenolic compounds widely distributed in plants and have many biological functions, such as anti-inflammatory, antioxidant, antiaging, and anticancer. Nowadays, flavonoids have been applied to the therapy of glioma; however, the molecular mechanism underlying the therapeutic effects has not been fully elaborated. This study was carried out to explore the mechanism of selected active flavonoid compounds in treating glioma using network pharmacology and molecular docking approaches.

METHODS

Active ingredients and associated targets of flavonoids were acquired by using the Traditional Chinese Medicine Database and Analysis Platform (TCMSP) and Swiss TargetPrediction platform. Genes related to glioma were obtained from the GeneCards and DisGeNET databases. The intersection targets between flavonoid targets and glioma-related genes were used to construct protein-protein interaction (PPI) network via the STRING database, and the results were analyzed by Cytoscape software. Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway enrichment analyses were performed and displayed by utilizing the Metascape portal and clusterProfiler R package. Molecular docking was carried out by iGEMDOCK and SwissDock, and the results were visually displayed by UCSF Chimera software.

RESULTS

Eighty-four active flavonoid compounds and 258 targets overlapped between flavonoid targets and glioma-related genes were achieved. PPI network revealed potential therapeutic targets, such as AKT1, EGFR, VEGFA, MAPK3, and CASP3, based on their node degree. GO and KEGG analyses showed that core targets were mainly enriched in the PI3K-Akt signaling pathway. Molecular docking simulation indicated that potential glioma-related targets-MAPK1 and HSP90AA1 were bounded more firmly with epigallocatechin-3-gallate (EGCG) than with quercetin.

CONCLUSIONS

The findings of this study indicated that selected active flavonoid compounds might play therapeutic roles in glioma mainly through the PI3K-Akt signaling pathway. Moreover, EGCG had the potential antiglioma activity by targeting MAPK1 and HSP90AA1.

Therapeutic benefits of flavonoids against neuroinflammation: a systematic review

Flavonoids are an important class of natural polyphenolic compounds reported to exert beneficial effects in cardiovascular and metabolic diseases, cancer, autoimmune and neurological disorders. Flavonoids possess potential antioxidant, anti-inflammatory, antiapoptotic and immuno-modulation properties. Intriguingly, the importance of flavonoids in different neurological disorders is gaining more attention due to the safety, better pharmacokinetic profile and blood-brain barrier penetration, cost-effectiveness and readiness for clinical uses/trials. Many in vitro and in vivo research studies have established the neuroprotective mechanism of flavonoids in the central nervous system (CNS) diseases. The present review summarizes the benefits of various classes of flavonoids (flavones, flavonols, flavanones, anthocyanidins, isoflavones, flavanols), chemical nature, classification, their occurrence and distribution, pharmacokinetics and bioavailability. The manuscript also presents available evidences relating to the role of flavonoids in regulating key signaling pathways such as nuclear factor kappa-light-chain-enhancer of activated B cells (NF-κB) pathway, mitogen-activated protein kinase (MAPK) pathway, Janus kinase and signal transducer and activator of transcription proteins (JAK/STAT) pathway, Toll-like receptors (TLR) pathway, nuclear factor erythroid 2-related factor 2 (Nrf2) pathway and cAMP response element-binding protein (CREB) pathway involved in neuroinflammation associated with major neurological disorders. Literature search was conducted using electronic databases like Google Scholar, Scopus, PubMed central, Springer search and Web of science. Chemical structures used in the present analysis were drawn using Chemdraw Professional 15.0 software. This collective information provides comprehensive knowledge on disease pathways and therapeutic benefits of flavonoids in neurological disorders, druggability and future scope for research.

An overview on therapeutic and medicinal potential of poly-hydroxy flavone viz. Heptamethoxyflavone, Kaempferitrin, Vitexin and Amentoflavone for management of Alzheimer's and Parkinson's diseases: a critical analysis on mechanistic insight

Neurodegenerative disorders occur when nerve cells in the brain or peripheral nervous system partial or complete fail in their functions and sometimes even die due to some injuries or aging. Neurodegenerative disorders such as Alzheimer's Disease (AD) and Parkinson's Disease (PD), have been majorly resulted due to degeneration of neurons and neuroinflammation progressively. There are many similarities that correlates both AD and PD on a cellular and sub-cellular level. Therefore, a hope for therapeutic advancement for simultaneous upgradation in both the diseases are directly depending on the discovery of common mechanism at molecular and cellular level. Recent and past evidences from scientific literature supporting the efficacy of plants flavonoids in treatment and protection of both AD and PD. Further, dietary flavones, specially Heptamethoxyflavone, Kaempferitrin, Vitexin and Amentoflavone gains recently much more attention for producing many health beneficiary effects including neuroprotection. Despite of these evidence a detailed updated overview of neuroprotective effects against both AD and PD by Heptamethoxyflavone, Kaempferitrin, Vitexin and Amentoflavone are still missing. In this context several published studies were assessed by using various online electronic search engines/databases to meet the objective from 1981 to 2021 (Approx. 224). Therefore, present review was designed to deliver the detailed description on these flavones including therapeutic benefits in AD, PD and other CNS complications with critical analysis on underlying mechanisms.

Alternative Targets to Fight Alzheimer's Disease: Focus on Astrocytes

The available treatments for patients affected by Alzheimer’s disease (AD) are not curative. Numerous clinical trials have failed during the past decades. Therefore, scientists need to explore new avenues to tackle this disease. In the present review, we briefly summarize the pathological mechanisms of AD known so far, based on which different therapeutic tools have been designed. Then, we focus on a specific approach that is targeting astrocytes. Indeed, these non-neuronal brain cells respond to any insult, injury, or disease of the brain, including AD. The study of astrocytes is complicated by the fact that they exert a plethora of homeostatic functions, and their disease-induced changes could be context-, time-, and disease specific. However, this complex but fervent area of research has produced a large amount of data targeting different astrocytic functions using pharmacological approaches. Here, we review the most recent literature findings that have been published in the last five years to stimulate new hypotheses and ideas to work on, highlighting the peculiar ability of palmitoylethanolamide to modulate astrocytes according to their morpho-functional state, which ultimately suggests a possible potential disease-modifying therapeutic approach for AD.

[Search for Neuroprotective Compounds -From 4-Methycatechol to Citrus Compounds]

In the 1980s, the authors developed the enzyme immunoassay (EIA) system for mouse nerve growth factor (NGF) to clarify its important physiological roles. Our EIA system was a new and powerful tool for measurement of extremely low levels of NGF in vitro and in vivo, and it contributed to investigation into the regulatory mechanism of NGF synthesis. After that, we demonstrated that the compounds with a low molecular weight, such as 4-methylcatechol, which elicit stimulatory activity toward NGF synthesis, were useful and practical for therapeutic purposes; as NGF has potent activity on neuronal degeneration in both the central nervous system (CNS) and the peripheral nervous system. Since 2008, we have been searching for and isolating neuroprotective component(s) from citrus peels. As a result, our study revealed that 1) 3,5,6,7,8,3',4'-heptamethoxyflavone (HMF) has neuroprotective ability in the CNS by inducing brain-derived neurotrophic factor (BDNF) and by suppressing inflammation; 2) auraptene (AUR) also has neuroprotective ability in the CNS by suppressing inflammation and by probably inducing neurotrophic factor(s). As the content of AUR in the peels of Kawachi Bankan is exceptionally high, 1) we found this peel powder to exert neuroprotective effects in the brain of various pathological model mice; 2) some of the AUR transited from the peel to the juice during the squeezing process to obtain the juice. Therefore, K. Bankan juice, which is enriched in AUR by adding peel paste to the raw juice, was shown to be practical for suppression of cognitive dysfunction of aged healthy volunteers.

Isolation and Characterization of Neuroprotective Components from Citrus Peel and Their Application as Functional Food

The elderly experience numerous physiological alterations. In the brain, aging causes degeneration or loss of distinct populations of neurons, resulting in declining cognitive function, locomotor capability, etc. The pathogenic factors of such neurodegeneration are oxidative stress, mitochondrial dysfunction, inflammation, reduced energy homeostatis, decreased levels of neurotrophic factor, etc. On the other hand, numerous studies have investigated various biologically active substances in fruit and vegetables. We focused on the peel of citrus fruit to search for neuroprotective components and found that: 1) 3,5,6,7,8,3',4'-heptamethoxyflavone (HMF) and auraptene (AUR) in the peel of Kawachi Bankan (Citrus kawachiensis) exert neuroprotective effects; 2) both HMF and AUR can pass through the blood-brain barrier, suggesting that they act directly in the brain; 3) the content of AUR in the peel of K. Bankan was exceptionally high, and consequently the oral administration of the dried peel powder of K. Bankan exerts neuroprotective effects; and 4) intake of K. Bankan juice, which was enriched in AUR by adding peel paste to the raw juice, contributed to the prevention of cognitive dysfunction in aged healthy volunteers. This review summarizes our studies in terms of the isolation/characterization of HMF and AUR in K. Bankan peel, analysis of their actions in the brain, mechanisms of their actions, and trials to develop food that retains their functions.

Beneficial Effects of Citrus-Derived Polymethoxylated Flavones for Central Nervous System Disorders

The number of patients with central nervous system disorders is increasing. Despite diligent laboratory and clinical research over the past 30 years, most pharmacologic options for the prevention and long-term treatment of central nervous system disorders and neurodegenerative disorders have been unsuccessful. Therefore, the development of drugs and/or functional foods to prevent the onset of neurodegenerative disorders is highly expected. Several reports have shown that polymethoxylated flavones (PMFs) derived from citrus fruit, such as nobiletin, tangeretin, and 3,3',4',5,6,7,8-heptamethoxyflavone, are promising molecules for the prevention of neurodegenerative and neurological disorders. In various animal models, PMFs have been shown to have a neuroprotective effect and improve cognitive dysfunction with regard to neurological disorders by exerting favorable effects against their pathological features, including oxidative stress, neuroinflammation, neurodegeneration, and synaptic dysfunction as well as its related mechanisms. In this review, we describe the profitable and ameliorating effects of citrus-derived PMFs on cognitive impairment and neural dysfunction in various rat and murine models or in several models of central nervous system disorders and identify their mechanisms of action.

[The Search for Citrus Components with Neuroprotective and Anti-dementia Effects in the Mouse Brain]

Citrus kawachiensis (Kawachi Bankan), is a citrus species grown in Ehime, Japan, and its peel is abundant in 3,5,6,7,8,3',4'-heptamethoxyflavone (HMF). We have recently revealed that HMF, one of the citrus flavonoids, has anti-inflammatory activity and neuroprotective abilities in the brain against global cerebral ischemia. HMF rescued neuronal cell death in the hippocampus and suppressed the activation of microglia, whose activation have been shown to significantly aggravate neurological deficit scores for ischemic mice. In the Y-maze test, HMF showed protection against ischemia-induced short-term memory dysfunction; in addition, HMF enhanced the expression of brain-derived neurotrophic factor and accelerated neurogenesis in the hippocampus. Similarly, the powder of the peel of C. kawachiensis showed anti-inflammatory activity and neuroprotective abilities in the ischemic brain. To further examine the effect of the peel of C. kawachiensis, we administered it to senescence-accelerated-mouse prone 8 (SAMP8) mice, which show memory impairment and brain inflammation, tau hyperphosphorylation, and neuronal dysfunction. The C. kawachiensis treatment inhibited microglial activation and the hyperphosphorylation of tau protein in hippocampal neurons, and also relieved the suppression of neurogenesis in the dentate gyrus of the hippocampus in SAMP8. These results suggest that HMF and the peel of C. kawachiensis have potential effects as neuroprotective and anti-dementia agents.

Development and Optimization of a High Sensitivity LC-MS/MS Method for the Determination of Hesperidin and Naringenin in Rat Plasma: Pharmacokinetic Approach

The purpose of this study was to develop, optimize, and fully validate a high-sensitivity methodology using UHPLC-MS/MS to simultaneously quantify hesperidin and naringenin in microsamples (100 µL) of murine plasma after intragastric administration of single pure flavonoids and a mixture. The optimization process allowed for high sensitivity with detection limits of approximately picogram order using an electrospray ionization (ESI) source in negative mode and an experiment based on multiple reaction monitoring (MRM). The validation parameters showed excellent linearity and detection limits, with a precision of less than 8% and a recovery of over 90%. This methodology was applied to compare the pharmacokinetic parameters for the administration of hesperidin and naringenin in individual form or in the form of a mixture. The results showed an absence of significant effects (p > 0.05) for Tmax and Cmax; however, the AUC presented significant differences (p < 0.05) for both flavonoids when administered as a mixture, showing an improved absorption ratio for both flavonoids.

Antidepressant-like Effect of Merazin Hydrate Depends on NO/ERK by Suppressing Its Downstream NF-κB or Nonactivating CREB/BDNF in Mouse Hippocampus

Merazin hydrate (MH), an essential ingredient of Fructus aurantii, has been identified to have an antidepressant-like effect. However, the molecular mechanisms of MH modulate depressive behavior are largely uncharacterized. Here, in lipopolysaccharide-induced mice, we identified that a single administration of MH recovered depressive behaviors and down-regulated the expressions of neuronal nitric oxide synthase (nNOS) in the hippocampus after 1 day. Activation of nNOS by l-arginine led to depressive behaviors, and inhibition of nNOS contributed to antidepressive behaviors. Notably, MH only reversed the expression of nNOS's downstream NF-κB and not the CREB/BDNF pathway in the hippocampus, and MH's antidepressant-like effects were prevented by Asatone (an agonist of NF-κB) and not H89 (an antagonist of CREB). MH also normalized the expressions of GFAP and IB-1 in dentate gyrus in the hippocampus and inflammatory factors such as IL-1β, IL-10, and TNF-α in serum. Overall, our studies reveal the molecular mechanisms of MH's antidepressant-like effect.

Design, Synthesis, and Biological Evaluation of Novel Multifunctional Rolipram-Tranilast Hybrids As Potential Treatment for Traumatic Brain Injury

Traumatic brain injury (TBI) is a prevalent public healthcare concern frequently instigated by mechanical shock, traffic, or violence incidents, leading to permanent nerve damage, and there is no ideal treatment for it yet. In this study, a series of Rolipram-Tranilast hybrids were designed and synthesized. The neuroprotective activities of the Rolipram-Tranilast hybrids were evaluated both in vitro and in vivo. Compound 5 has been identified as the strongest neuroprotective molecule among the series with robust anti-oxidant and anti-inflammatory potentials. Compound 5 significantly increased the heme oxygenase-1 (HO-1) levels and the phosphorylated cAMP response elements binding protein (p-CREB) while it down-regulated phosphodiesterase-4 B (PDE4B) expression in vitro. Furthermore, compound 5 remarkably attenuated TBI and had a good safety profile in mice. Taken together, our findings suggested that compound 5 could serve as a novel promising lead compound in the treatment of TBI and other central nervous system (CNS) diseases associated with PDE4B and oxidative stress.

Citrus Auraptene Induces Expression of Brain-Derived Neurotrophic Factor in Neuro2a Cells

(1) Background: Our published data have indicated that 1) auraptene (AUR), a citrus ingredient, has neuroprotective effects on the mouse brain, owing to its ability to suppress inflammation, such as causing a reduction in hyperactivation of microglia and astrocytes; 2) AUR has the ability to trigger phosphorylation (activation) of extracellular signal-related kinase (ERK) and cAMP response element-binding protein (CREB) in neuronal cells; 3) AUR has the ability to induce glial cell line-derived neurotrophic factor (GDNF) synthesis/secretion in rat C6 glioma cells. The well-established fact that the ERK-CREB pathway plays an important role in the production of neurotrophic factors, including GDNF and brain-derived neurotrophic factor (BDNF), prompted us to investigate whether AUR would also have the ability to induce BDNF expression in neuronal cells. (2) Methods: Mouse neuroblastoma neuro2a cells were cultured and the effects of AUR on BDNF mRNA expression and protein content were evaluated by RT-PCR and ELISA, respectively. (3) Results: The levels of BDNF mRNA and secreted BDNF were significantly increased by AUR in a dose- and time-dependent manner in neuro2a cells. (4) Conclusion: The induction of BDNF in neuronal cells might be, in part, one of the mechanisms accounting for the neuroprotective effects of AUR.

Role of phytochemicals as nutraceuticals for cognitive functions affected in ageing

Cognitive decline can occur with normal ageing and in age-related brain disorders, such as mild cognitive impairment and dementia, including Alzheimer's disease, with limited pharmacological therapies available. Other approaches to reduce cognitive decline are urgently needed, and so, the role of dietary interventions or nutraceuticals has received much attention in this respect. In this review, we examine the evidence for dietary plants and their chemical constituents as nutraceuticals, relevant to both cognitive decline in normal ageing and in dementia. Pharmacological (in vitro and in vivo), clinical and epidemiological evidence is assessed for both frequently consumed plants and their dietary forms, including tea, coffee, cocoa (chocolate), red wine, grapes, citrus and other fruits; in addition to plants used less frequently in certain diets and those that cross the blurred boundaries between foods, nutraceuticals and medicinal plants. For the latter, turmeric, saffron, sage, rosemary and lemon balm are examples of those discussed. LINKED ARTICLES: This article is part of a themed section on The Pharmacology of Nutraceuticals. To view the other articles in this section visit http://onlinelibrary.wiley.com/doi/10.1111/bph.v177.6/issuetoc.

Citrus Auraptene Induces Glial Cell Line-Derived Neurotrophic Factor in C6 Cells

We previously demonstrated that auraptene (AUR), a natural coumarin derived from citrus plants, exerts anti-inflammatory effects in the brain, resulting in neuroprotection in some mouse models of brain disorders. The present study showed that treatment with AUR significantly increased the release of glial cell line-derived neurotrophic factor (GDNF), in a dose- and time-dependent manner, by rat C6 glioma cells, which release was associated with increased expression of GDNF mRNA. These results suggest that AUR acted as a neuroprotective agent in the brain via not only its anti-inflammatory action but also its induction of neurotrophic factor. We also showed that (1) the AUR-induced GDNF production was inhibited by U0126, a specific inhibitor of mitogen-activated protein kinase/extracellular signal-regulated kinase (ERK) 1/2, and by H89, a specific inhibitor of protein kinase A (PKA); and (2) AUR induced the phosphorylation of cAMP response element-binding protein (CREB), a transcription factor located within the nucleus. These results suggest that AUR-stimulated gdnf gene expression was up-regulated through the PKA/ERK/CREB pathway in C6 cells.