Kaempferol Derivatives Prevent Oxidative Stress–Induced Cell Death in a DJ-1–Dependent Manner

Kaempferol, a potential neuroprotective agent in neurodegenerative diseases: From chemistry to medicine

Neurodegenerative diseases (NDDs) encompass a range of conditions that involve progressive deterioration and dysfunction of the nervous system. Some of the common NDDs include Alzheimer's disease (AD), Parkinson's disease (PD), Huntington's disease (HD), and amyotrophic lateral sclerosis (ALS). Although significant progress has been made in understanding the pathological mechanisms of NDDs in recent years, the development of targeted and effective drugs for their treatment remains challenging. Kaempferol is a flavonoid whose derivatives include kaempferol-O-rhamnoside, 3-O-β-rutinoside/6-hydroxykaempferol 3,6-di-O-β-d-glucoside, and kaempferide. Emerging studies have suggested that kaempferol and its derivatives possess neuroprotective properties and may have potential therapeutic benefits in NDDs. Here, we aimed to provide a theoretical basis for the use of kaempferol and its derivatives in the clinical treatment of NDDs. We systematically reviewed the literature in the PubMed, Web of Science, and Science Direct databases until June 2022 using the search terms "kaempferol," "kaempferol derivatives," "NDDs," "pharmacokinetics," and "biosynthesis" according to the reporting items for systematic review (PRISMA) standard. Based on combined results of in vivo and in vitro studies, we summarize the basic mechanisms and targets of kaempferol and its derivatives in the management of AD, PD, HD, and ALS. Kaempferol and its derivatives exert a neuroprotective role mainly by preventing the deposition of amyloid fibrils (such as Aβ, tau, and α-synuclein), inhibiting microglia activation, reducing the release of inflammatory factors, restoring the mitochondrial membrane to prevent oxidative stress, protecting the blood-brain barrier, and inhibiting specific enzyme activities (such as cholinesterase). Kaempferol and its derivatives are promising natural neuroprotective agents. By determining their pharmacological mechanism, kaempferol and its derivatives may be new candidate drugs for the treatment of NDDs.

Neurodegenerative Diseases and Flavonoids: Special Reference to Kaempferol

Neurodegenerative diseases like Alzheimer's disease, Parkinson's disease, Huntington's disease, Multiple Sclerosis and Ischemic stroke have become a major health problem worldwide. Pre-clinical studies have demonstrated the beneficial effects of flavonoids on neurodegenerative diseases and suggest them to be used as therapeutic agents. Kaempferol is found in many plants such as tea, beans, broccoli, strawberries, and neuroprotective effects against the development of many neurodegenerative diseases such as Parkinson, Alzheimer's disease and Huntington's disease. The present study summarizes the neuroprotective effects of kaempferol in various models of neurodegenerative diseases. Kaempferol delays the initiation as well as the progression of neurodegenerative disorders by acting as a scavenger of free radicals and preserving the activity of various antioxidant enzymes. Kaempferol can cross the Blood-Brain Barrier (BBB), and therefore results in an enhanced protective effect. The multi-target property of kaempferol makes it a potential dietary supplement in preventing and treating neurodegenerative diseases.

Greener extraction process and enhanced in vivo bioavailability of bioactive components from Carthamus tinctorius L. by natural deep eutectic solvents

Natural deep eutectic solvents (NaDESs) are promising green alternatives to conventional solvents widely applied in the extraction of natural products due to their physical and chemical superiorities. In present study, 22 NaDESs consisted from food grade ingredients were screened in ultrasonic assisted extraction (UAE) of bioactive compounds from safflower. The oral bioavailabilities of hydroxysafflor yellow A (HSYA) and anhydrosafflor yellow B (ASYB) in the extracts were then investigated in SD rats with the help of HPLC-MS technique. The results revealed that l-proline-acetamide (l-Pro-Am) was an effective solvent with the yields of HSYA and ASYB at 32.83 and 8.80 mg/g. Pharmacokinetic studies revealed that the blood level of HSYA and ASYB were significantly higher after oral administration of l-Pro-Am extract than that of aqueous extract. Especially, the relative bioavailabilities (to aqueous extract) of HSYA and ASYB were calculated 183.5% and 429.8%.

Effect of kaempferol on IgE-mediated anaphylaxis in C57BL/6 mice and LAD2 cells

BACKGROUND

Immunoglobulin E (IgE)-mediated mast cell (MC) activation is crucial in multiple allergic diseases. Parkinson disease protein 7 (DJ-1) and Lyn kinase were reported as the receptor-proximal events in IgE receptor (FcεRI) signals in human MC. Kaempferol, a natural flavonol mainly derived from the rhizome of traditional Chinese herb Kaempferia galanga L. (Zingiberaceae), has been known to inhibit allergic reactions, but it was limited to the receptor-distal signals on rat basophilic leukemia cells. A thorough investigation of the inhibitory effects of kaempferol on human MC has not been done.

PURPOSE

To investigate the inhibitory effects of kaempferol on IgE-mediated anaphylaxis in vivo and in human MCs, as well as the mechanism underlying its effects, especially the receptor-proximal signals.

METHODS

IgE-mediated passive cutaneous anaphylaxis and systemic anaphylaxis model were applied to elucidate the antiallergic activity of kaempferol in vivo. The degranulation assay, calcium imaging, the release of cytokines and chemokines on the laboratory of allergic disease 2 (LAD2) cells were used to evaluate the antiallergic effect of kaempferol in vitro. Western blot analysis was performed to investigate the DJ-1/Lyn signaling pathway and downstream molecules. Kinase activity assay, immunofluorescence, and molecular docking were conducted to confirm the influence of kaempferol on DJ-1/Lyn molecules.

RESULTS

Kaempferol dose-dependently attenuated ovalbumin/IgE-induced mice paw swelling, primary MC activation from paw skin, as well as rehabilitated the hypothermia, and reduced the serum concentrations of histamine, tumor necrosis factor-alpha, interleukin-8, and monocyte chemo-attractant protein-1. Additionally, kaempferol suppressed IgE-mediated LAD2 cell degranulation and calcium fluctuation. Remarkably, kaempferol was found to bind with DJ-1 protein, and initially prevented DJ-1 from translocating to the plasma membrane, thereby inhibited full activation of Lyn, and eventually restrained those receptor-distal signaling molecules, involved Syk, Btk, PLCγ, IP3R, PKC, MAPKs, Akt and NF-κB.

CONCLUSION

Kaempferol could be used as a DJ-1 modulator for preventing MC-mediated allergic disorders through attenuating Lyn activation.

Neuroprotective Effects of Safflower Flavonoid Extract in 6-Hydroxydopamine-Induced Model of Parkinson's Disease May Be Related to its Anti-Inflammatory Action

Safflower (Carthamus tinctorius. L.), a Chinese materia medica, is widely used for the treatment of cardiovascular and cerebrovascular diseases, with flavonoids being the major active components. Multiple flavonoids in safflower bind to Parkinson’s disease (PD)-related protein DJ-1. Safflower flavonoid extract (SAFE) improved behavioral indicators in a 6-hydroxydopamine (6-OHDA)-induced rat model of PD; however, the underlying mechanisms remain unclear. We used a 6-OHDA-induced mouse model of PD and a primary neuron-astrocyte coculture system to determine the neuroprotective effects and mechanisms of SAFE. After three weeks of SAFE administration, behavioral indicators of PD mice were improved. SAFE regulated the levels of tyrosine hydroxylase (TH) and dopamine metabolism. It significantly inhibited the activation of astrocytes surrounding the substantia nigra and reduced Iba-1 protein level in the striatum of PD mice. SAFE reduced the plasma content of inflammatory factors and suppressed the activation of nod-like receptor protein 3 (NLRP3) inflammasome. In the coculture system, kaempferol 3-O-rutinoside and anhydrosafflor yellow B significantly improved neuronal survival, suppressed neuronal apoptosis, and reduced IL-1β and IL-10 levels in the medium. Thus, SAFE showed a significant anti-PD effect, which is mainly associated with flavonoid anti-inflammatory activities.

The Pathology of Parkinson's Disease and Potential Benefit of Dietary Polyphenols

Parkinson's disease (PD) is a progressive neurodegenerative disorder that is characterized by a loss of dopaminergic neurons, leading to bradykinesia, rigidity, tremor at rest, and postural instability, as well as non-motor symptoms such as olfactory impairment, pain, autonomic dysfunction, impaired sleep, fatigue, and behavioral changes. The pathogenesis of PD is believed to involve oxidative stress, disruption to mitochondria, alterations to the protein α-synuclein, and neuroinflammatory processes. There is currently no cure for the disease. Polyphenols are secondary metabolites of plants, which have shown benefit in several experimental models of PD. Intake of polyphenols through diet is also associated with lower PD risk in humans. In this review, we provide an overview of the pathology of PD and the data supporting the potential neuroprotective capacity of increased polyphenols in the diet. Evidence suggests that the intake of dietary polyphenols may inhibit neurodegeneration and the progression of PD. Polyphenols appear to have a positive effect on the gut microbiome, which may decrease inflammation that contributes to the disease. Therefore, a diet rich in polyphenols may decrease the symptoms and increase quality of life in PD patients.

Hypoglycemic effects of phenolic compound-rich aqueous extract from water dropwort (Oenanthe javanica DC.) on streptozotocin-induced diabetic mice

Phenolic compounds in water dropwort aqueous extract were identified, and the IRS-2/PI3K-AKT pathway and GLUT4 translocation were regulated for hypoglycemic action.

Sulfated polysaccharides from Rhodiola sachalinensis reduce d-gal-induced oxidative stress in NIH 3T3 cells

In this study, three sulfated polysaccharides (S-RSP_1-2, S-RSP_1-4 and S-RSP_1-8) from Rhodiola sachalinensis were produced by chlorosulfonic acid-pyridine method. d-gal was used to develop an oxidative stress model in the mouse embryonic fibroblast cell line NIH 3T3. Effects of the three sulfated polysaccharides on d-gal-induced oxidative stress were investigated. The results showed that S-RSP_1-4 improved the viability of the d-gal-induced oxidative stress in NIH 3T3 cells. The sulfated polysaccharides were found to have a better protective effect against d-gal-induced oxidative stress as compared to the native polysaccharide. Scanning electronmicroscopy also showed a significant change in the surface morphology of sulfated polysaccharides. In addition, the sulfated polysaccharides had noticeable DPPH radical-scavenging activity. In summary, our results demonstrated that d-gal was able to induce oxidative stress in NIH 3T3 cells, and sulfated group might play an important role in resistance to d-gal-induced oxidative damage.

Allium porrum Extract Decreases Effector Cell Degranulation and Modulates Airway Epithelial Cell Function

Allium genus plants, such as leek (Allium porrum), are rich sources of anti-inflammatory and anti-oxidant secondary metabolites; this is of interest because it demonstrates their suitability as pharmacological alternatives for inflammatory processes, including allergy treatment. The composition of methanolic leek extract (LE) was analyzed by GC–MS and LC–IT/MS, and the total phenolic content and antioxidant capacity were quantified by colorimetric methods. Its pharmacological potential was analyzed in human bronchial epithelial Calu-3 cells, human mast cells LAD2, and humanized rat basophiles RBL-2H3. LE exhibited a cytotoxic effect on Calu-3 cells and HumRBL-2H3 cells only at high concentrations and in a dose-dependent manner. Moreover, LE decreased the degranulation of LAD2 and HumRBL-2H3 cells. LE treatment also significantly prevented alterations in transepithelial electrical resistance values and mRNA levels of glutathione-S-transferase (GST), c-Jun, and NFκB after treatment with H₂O₂ in ALI-cultured Calu-3 cells. Finally, ALI-cultured Calu-3 cells treated with LE showed lower permeability to Ole e 1 compared to untreated cells. A reduction in IL-6 secretion in ALI-cultured Calu-3 cells treated with LE was also observed. In summary, the results obtained in this work suggest that A. porrum extract may have potential anti-allergic effects due to its antioxidant and anti-inflammatory properties. This study provides several important insights into how LE can protect against allergy.

Chemo-preventive and therapeutic effect of the dietary flavonoid kaempferol: A comprehensive review

Kaempferol, a natural flavonoid present in several plants, possesses a wide range of therapeutic properties such as antioxidant, anticancer, and anti-inflammatory. It has a significant role in reducing cancer and can act as a therapeutic agent in the treatment of diseases and ailments such as diabetes, obesity, cardiovascular diseases, oxidative stress, asthma, and microbial contamination disorders. Kaempferol acts through different mechanisms: It induces apoptosis (HeLa cervical cancer cells), decreases cell viability (G2/M phase), downregulates phosphoinositide 3-kinase (PI3K)/AKT (protein kinase B) and human T-cell leukemia/lymphoma virus-I (HTLV-I) signaling pathways, suppresses protein expression of epithelial-mesenchymal transition (EMT)-related markers including N-cadherin, E-cadherin, Slug, and Snail, and metastasis-related markers such as matrix metallopeptidase 2 (MMP-2). Accordingly, the aim of the present review is to collect information pertaining to the effective role of kaempferol against various degenerative disorders, summarize the antioxidant, anti-inflammatory, anticancer, antidiabetic, and antiaging effects of kaempferol and to review the progress of recent research and available data on kaempferol as a protective and chemotherapeutic agent against several ailments.

Bio-effectiveness of the main flavonoids of Achillea millefolium in the pathophysiology of neurodegenerative disorders- a review

The Achillea millefolium L. (Yarrow) is a common herb which is widely being used, worldwide. Achillea is being used for treatment of many disorders since centuries. It is considered safe for supplemental use and flavonoids such as kaempferol, luteolin and apigenin are of main constituents present in Achillea. Most of both antioxidant and anti-inflammatory properties of this herb have been attributed to its flavonoid content. Oxidative and inflammatory processes play important roles in pathogenesis of neurodegenerative diseases. Present review was aimed to review the latest literature evidences regarding application of Achillea and/or its three main flavonoid constituents on epilepsy, Alzheimer's disease, multiple sclerosis, Parkinson's disease and stroke.

Intestinal absorption and neuroprotective effects of kaempferol-3-O-rutinoside

Kaempferol-3-O-rutinoside (K3R) has been proven to have biological activities for the prevention and treatment of central nervous system (CNS) diseases.

Neuroprotective Effects of a Standardized Flavonoid Extract from Safflower against a Rotenone-Induced Rat Model of Parkinson's Disease

Parkinson’s disease (PD) is a major age-related neurodegenerative disorder characterized by the loss of dopaminergic neurons in the substantia nigra par compacta (SNpc). Rotenone is a neurotoxin that is routinely used to model PD to aid in understanding the mechanisms of neuronal death. Safflower (Carthamus tinctorius. L.) has long been used to treat cerebrovascular diseases in China. This plant contains flavonoids, which have been reported to be effective in models of neurodegenerative disease. We previously reported that kaempferol derivatives from safflower could bind DJ-1, a protein associated with PD, and that a flavonoid extract from safflower exhibited neuroprotective effects in the 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine-induced mouse model of PD. In this study, a standardized safflower flavonoid extract (SAFE) was isolated from safflower and found to primarily contain flavonoids. The aim of the current study was to confirm the neuroprotective effects of SAFE in rotenone-induced Parkinson rats. The results showed that SAFE treatment increased body weight and improved rearing behavior and grip strength. SAFE (35 or 70 mg/kg/day) treatment reversed the decreased protein expression of tyrosine hydroxylase, dopamine transporter and DJ-1 and increased the levels of dopamine and its metabolite. In contrast, acetylcholine levels were decreased. SAFE treatment also led to partial inhibition of PD-associated changes in extracellular space diffusion parameters. These changes were detected using a magnetic resonance imaging (MRI) tracer-based method, which provides novel information regarding neuronal loss and astrocyte activation. Thus, our results indicate that SAFE represents a potential therapeutic herbal treatment for PD.

Neuroprotective Effects of A Standardized Flavonoid Extract of Safflower Against Neurotoxin-Induced Cellular and Animal Models of Parkinson's Disease

Safflower has long been used to treat cerebrovascular diseases in China. We previously reported that kaempferol derivatives of safflower can bind DJ-1, a protein associated with Parkinson’s disease (PD), and flavonoid extract of safflower exhibited neuroprotective effects in a 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine-induced mouse model of PD. In this study, a standardized safflower flavonoid extract (SAFE) was isolated from safflower and mainly contained flavonoids. Two marker compounds of SAFE, kaempferol 3-O-rutinoside and anhydrosafflor yellow B, were proven to suppress microtubule destabilization and decreased cell area, respectively. We confirmed that SAFE in dripping pill form could improve behavioural performances in a 6-hydroxydopamine (6-OHDA)-induced rat model of PD, partially via the suppression of α-synuclein overexpression or aggregation, as well as the suppression of reactive astrogliosis. Using an MRI tracer-based method, we found that 6-OHDA could change extracellular space (ECS) diffusion parameters, including a decrease in tortuosity and the rate constant of clearance and an increase in the elimination half-life of the tracer in the 6-OHDA-lesioned substantia nigra. SAFE treatment could partially inhibit the changes in ECS diffusion parameters, which might provide some information about neuronal loss and astrocyte activation. Consequently, our results indicate that SAFE is a potential therapeutic herbal product for treatment of PD.

Common mechanisms of onset of cancer and neurodegenerative diseases

Onset of cancer and neurodegenerative disease occurs by abnormal cell growth and neuronal cell death, respectively, and the number of patients with both diseases has been increasing in parallel with an increase in mean lifetime, especially in developed countries. Although both diseases are sporadic, about 10% of the diseases are genetically inherited, and analyses of such familial forms of gene products have contributed to an understanding of the molecular mechanisms underlying the onset and pathogenesis of these diseases. I have been working on c-myc, a protooncogene, for a long time and identified various c-Myc-binding proteins that play roles in c-Myc-derived tumorigenesis. Among these proteins, some proteins have been found to be also responsible for the onset of neurodegenerative diseases, including Parkinson's disease, retinitis pigmentosa and cerebellar atrophy. In this review, I summarize our findings indicating the common mechanisms of onset between cancer and neurodegenerative diseases, with a focus on genes such as DJ-1 and Myc-Modulator 1 (MM-1) and signaling pathways that contribute to the onset and pathogenesis of cancer and neurodegenerative diseases.

Role of oxidative stress in Parkinson's disease

Parkinson's disease (PD) is a progressive neurodegenerative movement disorder associated with a selective loss of the dopamine(DA)rgic neurons in the substantia nigra pars compacta and the degeneration of projecting nerve fibers in the striatum. Because there is currently no therapy that delays the neurodegenerative process, modification of the disease course by neuroprotective therapy is an important unmet clinical need. Toward this end, understanding cellular mechanisms that render the nigral neurons particularly vulnerable have been a subject of intensive research. Increasing evidence suggests that oxidative stress plays a major role. The metabolism of DA itself contributes to oxidative stress, resulting in modification of intracellular macromolecules whose functions are important for cell survival. Mitochondrial dysfunction and the consequent increase in reactive oxygen species also trigger a sequence of events that leads to cell demise. In addition, activated microglia produce nitric oxide and superoxide during neuroinflammatory responses, and this is aggravated by the molecules released by damaged DAergic neurons such as α-synuclein, neuromelanin and matrix metalloproteinase-3. Ways to reduce oxidative stress therefore can provide a therapeutic strategy. NAD(P)H:quinone reductase (NQO1) and other antioxidant enzymes, whose gene expression are commonly under the regulation of the transcription factor Nrf2, can serve as target proteins utilized toward development of disease-modifying therapy for PD.

Kale extract increases glutathione levels in V79 cells, but does not protect them against acute toxicity induced by hydrogen peroxide

This study aims to evaluate the antioxidant potential of extracts of Brassica oleracea L. var. acephala DC. (kale) and several materials of Pieris brassicae L., a common pest of Brassica cultures using a cellular model with hamster lung fibroblast (V79 cells) under quiescent conditions and subjected to H₂O₂-induced oxidative stress. Cytotoxicity was evaluated by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide (MTT) assay and glutathione was determined by the 5,5'-dithiobis(2-nitrobenzoic acid) (DTNB)-oxidized glutathione (GSSG) reductase recycling assay. The phenolic composition of the extracts was also established by HPLC-DAD. They presented acylated and non acylated flavonoid glycosides, some of them sulfated, and hydroxycinnamic acyl gentiobiosides. All extracts were cytotoxic by themselves at high concentrations and failed to protect V79 cells against H₂O₂ acute toxicity. No relationship between phenolic composition and cytotoxicity of the extracts was found. Rather, a significant increase in glutathione was observed in cells exposed to kale extract, which contained the highest amount and variety of flavonoids. It can be concluded that although flavonoids-rich extracts have the ability to increase cellular antioxidant defenses, the use of extracts of kale and P. brassicae materials by pharmaceutical or food industries, may constitute an insult to health, especially to debilitated individuals, if high doses are consumed.

Neuroprotective effect of kaempferol against a 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine-induced mouse model of Parkinson's disease

In the present study, we investigated the neuroprotective effects of kaempferol in the mouse model of Parkinson's disease, which was induced by neurotoxin 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP). We confirmed that MPTP led to behavioral deficits, depletion of dopamine and its metabolites, reduction in superoxide dismutase (SOD) and glutathione peroxidase (GSH-PX) activity, and the elevation of malondialdehyde (MDA) levels in the substantia nigra. When administered prior to MPTP, kaempferol improved motor coordination, raised striatal dopamine and its metabolite levels, increased SOD and GSH-PX activity, and reduced the content of MDA compared with mice treated with MPTP alone. Immunohistochemical studies using anti-tyrosine hydroxylase (TH) antibody showed that medication of kaempferol could prevent the loss of TH-positive neurons induced by MPTP. Taken together, we propose that kaempferol has shown anti-parkinsonian properties in our studies. More work is needed to explore detailed mechanisms of action.

DJ-1 cleavage by matrix metalloproteinase 3 mediates oxidative stress-induced dopaminergic cell death

Oxidative stress is commonly implicated in aging and neurodegenerative conditions such as Parkinson's disease (PD). Mutations in DJ-1 are associated with autosomal recessive early-onset PD. We investigated whether DJ-1 can be degraded in oxidative-stressed dopaminergic neuronal cells, leading to loss of its protective role against oxidative stress. We have shown previously and herein that the active form of matrix metalloproteinase-3 (MMP3) was accumulated in dopamine-producing CATH.a cells in the presence of MPP(+). We show that catalytically active MMP3 cleaved DJ-1, and impaired its antioxidant function. In CATH.a cells, both monomeric and dimeric forms of DJ-1 were diminished in the presence of MPP(+), and this was reversed by MMP3 knockdown or inhibition. While DJ-1 expression was decreased in the substantia nigra of mice administered with MPTP, its degradation was largely attenuated in MMP3 knockout mice. The AKT-signaling pathway, thought to mediate the effect of DJ-1 on cell survival, was also altered. MPP(+) caused decrease in both phospho-Thr308 and phospho-Ser473 forms of AKT, and this was restored by NNGH. Our data suggest that DJ-1 is fragmented by the intracellular MMP3 in response to cell stress, abolishing the protective role of DJ-1 against oxidative damage, and this contributes to the pathogenesis of PD.

The role of oxidative stress in neuromelanin synthesis in PC12 cells

Previous research has indicated that neuromelanin (NM) is involved in the pathogenesis of Parkinson's disease (PD). Increased reactive oxygen species (ROS) generation in PD sufferers is thought to be related to enhanced tyrosine hydroxylase (TH) activity and NM production. However, few reports have confirmed this hypothesis. In this study, PC12 cells of all experiments were exposed to 50 μmol/L levodopa (l-DOPA) to generate a model for NM synthesis. Meanwhile, PC12 cells were treated with glucose oxidase (GO) at different concentrations to generate oxidative stress. Finally, cell viability, TH activity, and NM generation in PC12 cells were measured. The results showed that GO dose-dependently stimulated oxidative stress generation in PC12 cells. Moderate increases in oxidative stress enhanced the viability of PC12 cells. However, an excessive level of oxidative stress can lead to the degeneration of PC12 cells. Notably, in the surviving PC12 cells, ROS significantly increased the TH activity, and the NM production was also upregulated. Thus, oxidative stress may upregulate the synthesis of NM, which may be a result of the increased TH activity observed in response to the elevated ROS in l-DOPA-treated PC12 cells.

A strong protective action of guttiferone-A, a naturally occurring prenylated benzophenone, against iron-induced neuronal cell damage

Guttiferone-A (GA) is a natural occurring polyisoprenylated benzophenone with several reported pharmacological actions. We have assessed the protective action of GA on iron-induced neuronal cell damage by employing the PC12 cell line and primary culture of rat cortical neurons (PCRCN). A strong protection by GA, assessed by the 2,3-bis(2-methoxy-4-nitro-5-sulfophenyl)-2H-tetrazolium-5-carbox-anilide (XTT) assay, was revealed, with IC(50) values <1 µM. GA also inhibited Fe(3+)-ascorbate reduction, iron-induced oxidative degradation of 2-deoxiribose, and iron-induced lipid peroxidation in rat brain homogenate, as well as stimulated oxygen consumption by Fe(2+) autoxidation. Absorption spectra and cyclic voltammograms of GA-Fe(2+)/Fe(3+) complexes suggest the formation of a transient charge transfer complex between Fe(2+) and GA, accelerating Fe(2+) oxidation. The more stable Fe(3+) complex with GA would be unable to participate in Fenton-Haber Weiss-type reactions and the propagation phase of lipid peroxidation. The results show a potential of GA against neuronal diseases associated with iron-induced oxidative stress.

Neuroprotection by spice-derived nutraceuticals: you are what you eat!

Numerous lines of evidence indicate that chronic inflammation plays a major role in the development of various neurodegenerative diseases, including Alzheimer's disease, Parkinson's disease, multiple sclerosis, brain tumor, and meningitis. Why these diseases are more common among people from some countries than others is not fully understood, but lifestyle factors have been linked to the development of neurodegenerative diseases. For example, the incidence of certain neurodegenerative diseases among people living in the Asian subcontinent, where people regularly consume spices, is much lower than in countries of the western world. Extensive research over the last 10 years has indicated that nutraceuticals derived from such spices as turmeric, red pepper, black pepper, licorice, clove, ginger, garlic, coriander, and cinnamon target inflammatory pathways, thereby may prevent neurodegenerative diseases. How these nutraceuticals modulate various pathways and how they exert neuroprotection are the focus of this review.

Protective effect of trifluoperazine on hydrogen peroxide-induced apoptosis in PC12 cells

This study investigated effects of trifluoperazine (TFP) against the cytotoxicity induced by H₂O₂ in PC12 cells and the mechanisms thereof. Different concentrations of H₂O₂ (100-500 μM) induced a significant decrease in cell viability accompanied by increased oxidative stress and cell apoptosis. Pretreatment with TFP inhibited H₂O₂-induced cell viability loss. The flow cytometric assay showed that TFP can inhibit intracellular reactive oxygen species (ROS) generation and reduce the cell apoptosis. The electrophysiological recordings indicated that when treated with H₂O₂, the calcium current was significantly increased. Pretreatment with TFP increased mitochondrial membrane potential (MMP) in cells of oxidative injury. These results suggested that TFP can reduce apoptosis by inhibiting ROS generation and preventing loss of MMP in cells. Meanwhile, the protective effect of TFP on the cell apoptosis may be related to the calcium overload. TFP may inhibit the calcium overload process to achieve the protection against apoptosis.

DJ-1 and prevention of oxidative stress in Parkinson's disease and other age-related disorders

Mutations in the PARK7/DJ-1 gene are rare causes of autosomal-recessive hereditary Parkinson's disease. Loss-of-function mutations lead to the characteristic selective neurodegeneration of nigrostriatal dopaminergic neurons, which accounts for parkinsonian symptoms. Originally identified as an oncogene, DJ-1 is a ubiquitous redox-responsive cytoprotective protein with diverse functions. In addition to cell-autonomous neuroprotective roles, DJ-1 may act in a transcellular manner, being up-regulated in reactive astrocytes in chronic neurodegenerative diseases as well as in stroke. Thus, DJ-1, particularly in its oxidized form, has been recognized as a biomarker for cancer and neurodegenerative diseases. The crystal structure of DJ-1 has been solved, allowing detailed investigations of the redox-reactive center of DJ-1. Structure-function studies revealed that DJ-1 may become activated in the presence of reactive oxygen species, under conditions of oxidative stress, but also as part of physiological receptor-mediated signal transduction. DJ-1 regulates redox signaling kinase pathways and acts as a transcriptional regulator of antioxidative gene batteries. Therefore, DJ-1 is an important redox-reactive signaling intermediate controlling oxidative stress after ischemia, upon neuroinflammation, and during age-related neurodegenerative processes. Augmenting DJ-1 activity might provide novel approaches to treating chronic neurodegenerative illnesses such as Parkinson's disease and acute damage such as stroke.