Combining 99mTc-GSA single-photon emission-computed tomography and Gd-EOB-DTPA-enhanced magnetic resonance imaging for staging liver fibrosis.

Preoperative assessment of the degree of liver fibrosis is important to determine treatment strategies. In this study, galactosyl human serum albumin single-photon emission-computed tomography and ethoxybenzyl (EOB) contrast-enhanced magnetic resonance imaging (MRI) were used to assess the changes in hepatocyte function after liver fibrosis, and the standardized uptake value (SUV) was combined with gadolinium EOB-diethylenetriaminepentaacetic acid to evaluate its added value for liver fibrosis staging. A total of 484 patients diagnosed with hepatocellular carcinoma who underwent liver resection between January 2010 and August 2018 were included. Resected liver specimens were classified based on pathological findings into nonfibrotic and fibrotic groups (stratified according to the Ludwig scale). Galactosyl human serum albumin-single-photon emission-computed tomography and EOB contrast-enhanced MRI examinations were performed, and the mean SUVs (SUVmean) and contrast enhancement indices (CEIs) were obtained. The diagnostic value of the acquired SUV and CEIs for fibrosis was assessed by calculating the area under the receiver operating characteristic curve (AUC). In the receiver operating characteristic analysis, SUV + CEI showed the highest AUC in both fibrosis groups. In particular, in the comparison between fibrosis groups, SUV + CEI showed significantly higher AUCs than SUV and CEI alone in discriminating between fibrosis (F3 and 4) and no or mild fibrosis (F0 and 2) (AUC: 0.879, vs SUV [P = 0.008], vs. CEI [P = 0.023]), suggesting that the combination of SUV + CEI has greater diagnostic performance than the individual indices. Combining the SUV and CEI provides high accuracy for grading liver fibrosis, especially in differentiating between grades F0 and 2 and F3-4. SUV and gadolinium EOB-diethylenetriaminepentaacetic acid-enhanced MRI can be noninvasive diagnostic methods to guide the selection of clinical treatment options for patients with liver diseases.

Optimization of the Linker Length in the Dimer Model of E22P-Aß40 Tethered at Position 38.

Since amyloid ß (Aß) oligomers are more cytotoxic than fibrils, various dimer models have been synthesized. We focused on the C-terminal region that could form a hydrophobic core in the aggregation process and identified a toxic conformer-restricted dimer model (E22P,G38DAP-Aß40 dimer) with an l,l-2,6-diaminopimelic acid linker (n = 3) at position 38, which exhibited moderate cytotoxicity. We synthesized four additional linkers (n = 2, 4, 5, 7) to determine the most appropriate distance between the two Aß40 monomers for a toxic dimer model. Each di-Fmoc-protected two-valent amino acid was synthesized from a corresponding dialdehyde or cycloalkene followed by ozonolysis, using a Horner-Wadsworth-Emmons reaction and asymmetric hydrogenation. Then, the corresponding Aß40 dimer models with these linkers at position 38 were synthesized using the solid-phase Fmoc strategy. Their cytotoxicity toward SH-SY5Y cells suggested that the shorter the linker length, the stronger the cytotoxicity. Particularly, the E22P,G38DAA-Aß40 dimer (n = 2) formed protofibrillar aggregates and exhibited the highest cytotoxicity, equivalent to E22P-Aß42, the most cytotoxic analogue of Aß42. Ion mobility-mass spectrometry (IM-MS) measurement indicated that all dimer models except the E22P,G38DAA-Aß40 dimer existed as stable oligomers (12-24-mer). NativePAGE analysis supported the IM-MS data, but larger oligomers (30-150-mer) were also detected after a 24 h incubation. Moreover, E22P,G38DAA-Aß40, E22P,G38DAP-Aß40, and E22P,G38DAZ-Aß40 (n = 5) dimers suppressed long-term potentiation (LTP). Overall, the ability to form fibrils with cross ß-sheet structures was key to achieving cytotoxicity, and forming stable oligomers less than 150-mer did not correlate with cytotoxicity and LTP suppression.

Structure Optimization of the Toxic Conformation Model of Amyloid ß42 by Intramolecular Disulfide Bond Formation.

Amyloid ß (Aß) oligomers play a critical role in the pathology of Alzheimer's disease. Recently, we reported that a conformation-restricted Aß42 with an intramolecular disulfide bond through cysteine residues at positions 17/28 formed stable oligomers with potent cytotoxicity. To further optimize this compound as a toxic conformer model, we synthesized three analogues with a combination of cysteine and homocysteine at positions 17/28. The analogues with Cys-Cys, Cys-homoCys, or homoCys-Cys, but not the homoCys-homoCys analogue, exhibited potent cytotoxicity against SH-SY5Y and THP-1 cells even at 10 nM. In contrast, the cytotoxicity of conformation-restricted analogues at positions 16/29 or 18/27 was significantly weaker than that of wild-type Aß42. Furthermore, thioflavin-T assay, non-denaturing gel electrophoresis, and morphological studies suggested that the majority of these conformation-restricted analogues exists in an oligomeric state in cell culture medium, indicating that the toxic conformation of Aß42, rather than the oligomeric state, is essential to induce cytotoxicity.

Histamine enhances ATP-induced itching and responsiveness to ATP in keratinocytes.

Mechanical stimulation of cultured keratinocytes and a living epidermis increases intracellular calcium ion concentrations ([Ca2+]i) in stimulated cells. This action propagates a Ca2+ wave to neighboring keratinocytes via ATP/P2Y2 receptors. Recent behavioral, pharmacological studies revealed that exogenous ATP induces itching via P2X3 receptors in mice. We previously showed that alloknesis occurs when an external stimulus is applied to the skin with increased epidermal histamine in the absence of spontaneous pruritus. Based on these results, we investigated the effects of histamine at a concentration that does not cause itching on ATP-induced itching. The mean number of scratching events induced by the mixture of ATP and histamine increased by 28% over the sum of that induced by histamine alone or ATP alone. A317491, a P2X3 receptor antagonist, suppressed the mixture-induced scratching more often than the ATP-induced scratching. Next, we examined the ATP-induced [Ca2+]i change before and after histamine stimulation using normal human epidermal keratinocytes. Some cells did not respond to ATP before histamine stimulation but responded to ATP afterward, the phenomenon suppressed by chlorpheniramine maleate. These findings suggest that histamine enhances ATP-induced itching and that a potential mechanism could involve increased responsiveness to ATP in keratinocytes.

Fernblock® Upregulates NRF2 Antioxidant Pathway and Protects Keratinocytes from PM2.5-Induced Xenotoxic Stress.

Humans in modern industrial and postindustrial societies face sustained challenges from environmental pollutants, which can trigger tissue damage from xenotoxic stress through different mechanisms. Thus, the identification and characterization of compounds capable of conferring antioxidant effects and protection against these xenotoxins are warranted. Here, we report that the natural extract of Polypodium leucotomos named Fernblock®, known to reduce aging and oxidative stress induced by solar radiations, upregulates the NRF2 transcription factor and its downstream antioxidant targets, and this correlates with its ability to reduce inflammation, melanogenesis, and general cell damage in cultured keratinocytes upon exposure to an experimental model of fine pollutant particles (PM2.5). Our results provide evidence for a specific molecular mechanism underpinning the protective activity of Fernblock® against environmental pollutants and potentially other sources of oxidative stress and damage-induced aging.

Protective Effect of 2',3'-Dihydroxy-4',6'-dimethoxychalcone on Glutamate-Induced Neurotoxicity in Primary Cortical Cultures.

We have previously isolated 2',3'-dihydroxy-4',6'-dimethoxychalcone (DDC) from green perilla leaves as the activator of the nuclear factor erythroid 2-related factor 2 (Nrf2)-antioxidant response element (ARE) pathway. This study aims to evaluate the effects of DDC against glutamate neurotoxicity using rat primary cortical cultures. Treatment of cultures with DDC for 24 h before glutamate exposure significantly inhibited glutamate neurotoxicity in a concentration-dependent manner. The involvement of hemeoxygenase-1 (HO-1) and reduced glutathione (GSH) in the protective effects of DDC on cortical cultures was also evaluated. While an HO-1 inhibitor did not have a significant effect on DDC-induced neuroprotection, a γ-glutamylcystein synthetase (γ-GCS) inhibitor significantly suppressed the protective effect of DDC. In an astrocyte culture, DDC induced a marked increase in the levels of intracellular reduced GSH. These results suggest that DDC mainly activates the Nrf2-ARE pathway of astrocytes, resulting in the increased extracellular release of reduced GSH, protecting neurons from glutamate neurotoxicity.

Effects of 2'-3'-dihydroxy-4',6'-dimethoxychalcone derived from green perilla on auricle thickness in chronic contact dermatitis model mice.

Oxidative stress has been implicated in the pathogenesis of allergic contact dermatitis. The nuclear factor erythroid 2-related factor 2 (Nrf2)-antioxidant response element (ARE) pathway, an in vivo antioxidant system, induces antioxidant enzymes. In our previous studies, we isolated 2',3'-dihydroxy-4',6'-dimethoxychalcone (DDC) from green perilla and identified it as a novel activator of the Nrf2-ARE pathway. We also discovered that it exerted cytoprotective effects against oxidative stress in PC12 cells. However, its effects on skin disease model animals in vivo remain unclear. In the present study, auricular thickness time-dependently increased with the repeated application of picryl chloride, and significant increases were observed from Day 2 in chronic contact hypersensitivity (cCHS) model mice. Histological changes, such as higher numbers of cells in the epidermis, were observed with increases in auricular thickness. The administration of DDC every two days from Day 6 suppressed the increases in auricular thickness and the number of scratching events in a dose-dependent manner. The expression levels of antioxidant enzymes increased in the mouse auricle 24 h after the administration of DDC. These results presume that DDC inhibits increases in auricular thickness in cCHS mice by up-regulating the expression of antioxidative enzymes through the activation of the Nrf2-ARE pathway.

Protective Effects of 2',3'-Dihydroxy-4',6'-dimethoxychalcone Derived from Green Perilla Leaves against UV Radiation-Induced Cell Injury in Human Cultured Keratinocytes.

Skin exposure to UV rays causes the production of reactive oxygen species (ROS), and it is a major risk factor for various skin disorders and diseases. In particular, exposure to UV-A is a major cause of photoaging. We have previously isolated 2',3'-dihydroxy-4',6'-dimethoxychalcone (DDC) from green perilla leaves as an activator of the nuclear factor erythroid 2-related factor-2 (Nrf2)-antioxidant response element (ARE) and demonstrated the protective effects of DDC both in vitro and in vivo in PC12 cells and Parkinson's disease models, respectively. In this study, we used HaCaT cells to examine the effects of DDC on ROS production and cell damage induced by UV-A. Our results indicated that UV-A irradiation in HaCaT cells increased ROS production in an energy-dependent manner. In addition, cell viability decreased in an energy-dependent manner 24 h after UV-A irradiation. However, treatment with DDC 24 h prior to UV-A irradiation significantly suppressed UV-A radiation-induced ROS production. In addition, DDC showed cytoprotective effects when used 24 h before and after UV-A irradiation. Treatment with DDC for 24 h also increased the expression levels of heme oxygenase-1 (HO-1) in a concentration-dependent manner. Pretreatment with the HO-1 inhibitor followed by DDC treatment before UV-A irradiation for 24 h reduced ROS production and the cytoprotective effect. These results suggest that DDC increases the expression levels of HO-1 and protects HaCaT cells through the suppression of UV radiation-induced ROS production.

Neuroprotective effect of an Nrf2-ARE activator identified from a chemical library on dopaminergic neurons.

The nuclear factor erythroid 2-related factor 2 (Nrf2)-antioxidant response element (ARE) pathway, which induces the production of antioxidant enzymes, is a possible therapeutic target for treating diseases related to oxidative stress. Nrf2 activators often exhibit cytotoxicity due to nonspecific electrophilic reactions with thiol groups. We screened a chemical library to explore Nrf2 activators with a wide safety margin. In at least in vitro experiments, TPNA10168, identified from the library, showed a higher efficacy in Nrf2 activation and a lower cytotoxicity than sulforaphane, a well-known Nrf2 activator. The present study demonstrated the protective effect of TPNA10168 against 6-hydroxydopamine-induced cytotoxicity. In PC12 cells, NAD(P)H:quinone oxidoreductase 1 was upregulated by TPNA10168 and participated in the protective effect. In primary mesencephalic cultures, heme oxygenase-1, upregulated by TPNA10168 in astrocytes, provided protection of dopaminergic neurons via a guanylate cyclase/protein kinase G signaling pathway via carbon monoxide. These results suggest that the compound identified from the chemical library may be suitable as a neuroprotective agent with the ability to induce antioxidant enzymes.

PE859, A Novel Curcumin Derivative, Inhibits Amyloid-ß and Tau Aggregation, and Ameliorates Cognitive Dysfunction in Senescence-Accelerated Mouse Prone 8.

Aggregation of amyloid-ß (Aß) and tau plays a crucial role in the onset and progression of Alzheimer's disease (AD). Therefore, the inhibition of Aß and tau aggregation may represent a potential therapeutic target for AD. Herein, we designed and synthesized both Aß and tau dual aggregation inhibitors based on the structure of curcumin and developed the novel curcumin derivative PE859. In this study, we investigated the inhibitory activity of PE859 on Aß aggregationin vitro and the therapeutic effects of PE859 on cognitive dysfunction via dual inhibition of Aß and tau aggregation in vivo. PE859 inhibited Aß aggregation in vitro and protected cultured cells from Aß-induced cytotoxicity. Furthermore, PE859 ameliorated cognitive dysfunction and reduced the amount of aggregated Aß and tau in brains of senescence-accelerated mouse prone 8 (SAMP8). These results warrant consideration of PE859 as a candidate drug for AD.

Inhibitory effect of donepezil on bradykinin-induced increase in the intracellular calcium concentration in cultured cortical astrocytes.

Donepezil is a potent and selective acetylcholinesterase inhibitor developed for the treatment of Alzheimer's disease. In the present study, we investigated the responses of astrocytes to bradykinin, an inflammatory mediator, and the effect of donepezil on these responses using cultured cortical astrocytes. Bradykinin induced a transient increase of intracellular calcium concentration ([Ca2+]i) in cultured astrocytes. Bradykinin-induced [Ca2+]i increase was inhibited by the exposure to thapsigargin, which depletes Ca2+ stores on endoplasmic reticulum, but not by the exclusion of extracellular Ca2+. Twenty four hours pretreatment of donepezil reduced the bradykinin-induced [Ca2+]i increase. This reduction was inhibited not only by mecamylamine, a nAChR antagonist, but also by PI3K and Akt inhibitors. In addition, donepezil inhibited bradykinin-induced increase of the intracellular reactive oxygen species level in astrocytes. These results suggest that donepezil inhibits the inflammatory response induced by bradykinin via nAChR and PI3K-Akt pathway in astrocytes.

Monoclonal antibody with conformational specificity for a toxic conformer of amyloid ß42 and its application toward the Alzheimer's disease diagnosis.

Amyloid ß-protein (Aß42) oligomerization is an early event in Alzheimer's disease (AD). Current diagnostic methods using sequence-specific antibodies against less toxic fibrillar and monomeric Aß42 run the risk of overdiagnosis. Hence, conformation-specific antibodies against neurotoxic Aß42 oligomers have garnered much attention for developing more accurate diagnostics. Antibody 24B3, highly specific for the toxic Aß42 conformer that has a turn at Glu22 and Asp23, recognizes a putative Aß42 dimer, which forms stable and neurotoxic oligomers more potently than the monomer. 24B3 significantly rescues Aß42-induced neurotoxicity, whereas sequence-specific antibodies such as 4G8 and 82E1, which recognizes the N-terminus, do not. The ratio of toxic to total Aß42 in the cerebrospinal fluid of AD patients is significantly higher than in control subjects as measured by sandwich ELISA using antibodies 24B3 and 82E1. Thus, 24B3 may be useful for AD diagnosis and therapy.

Reduction of Immunoreactivity Against the C-Terminal Region of the Intracellular α-Synuclein by Exogenous α-Synuclein Aggregates: Possibility of Conformational Changes.

BACKGROUND: The formation of intracellular aggregates containing α-synuclein (α-syn) is a main pathological feature of Parkinson disease. The propagation of α-syn aggregation via cell-to-cell transmission has been implicated in the progression of Parkinson disease. OBJECTIVE: Our aim is to clarify the molecular mechanisms underlying the formation of intracellular aggregation by extracellular α-syn. METHODS: We investigated the effects of exogenous α-syn aggregates on intracellular α-syn immunoreactivity in α-syn-overexpressing SH-SY5Y cells using two antibodies to distinct epitopes of α-syn. To obtain α-syn aggregates, α-syn solution was aged with continuous agitation. RESULTS: Immunoreactivity against the acidic C-terminal domain of the intracellular α-syn was reduced by exposure to agedα-syn, whereas that against the hydrophobic non-amyloid component region was not changed. The reduction in immunoreactivity was not suppressed by protease inhibitors but was mimicked by neutralization of the negative charges on the C-terminal of the intracellular α-syn induced by spermine or extracellular acidification. CONCLUSIONS: These results suggest that the reduction in immunoreactivity is attributed not to proteolytic cleavage but to a conformational change at the C-terminus of the intracellular α-syn. The conformational change at the C-terminus of the intracellular α-syn might be involved in an initial step of fibril formation by exogenous α-syn aggregates.

10-Oxo-trans-11-octadecenoic acid generated from linoleic acid by a gut lactic acid bacterium Lactobacillus plantarum is cytoprotective against oxidative stress.

Oxidative stress is a well-known cause of multiple diseases. The nuclear factor erythroid 2-related factor 2 (Nrf2)-antioxidant response element (ARE) pathway plays a central role in cellular antioxidative responses. In this study, we investigated the effects of novel fatty acid metabolite derivatives of linoleic acid generated by the gut lactic acid bacteria Lactobacillus plantarum on the Nrf2-ARE pathway. 10-Oxo-trans-11-octadecenoic acid (KetoC) protected HepG2 cells from cytotoxicity induced by hydrogen peroxide. KetoC also significantly increased cellular Nrf2 protein levels, ARE-dependent transcription, and the gene expression of antioxidative enzymes such as heme oxygenase-1 (HO-1), glutamate-cysteine ligase modifier subunit (GCLM), and NAD(P)H: quinone oxidoreductase 1 (NQO1) in HepG2 cells. Additionally, a single oral dose administration of KetoC also increased antioxidative gene expression and protein levels of Nrf2 and HO-1 in mouse organs. Since other fatty acid metabolites and linoleic acid did not affect cellular antioxidative responses, the cytoprotective effect of KetoC may be because of its α,ß-unsaturated carbonyl moiety. Collectively, our data suggested that KetoC activated the Nrf2-ARE pathway to enhance cellular antioxidative responses in vitro and in vivo, which further suggests that KetoC may prevent multiple diseases induced by oxidative stress.

Compensatory role of the Nrf2-ARE pathway against paraquat toxicity: Relevance of 26S proteasome activity.

Oxidative stress and the ubiquitin-proteasome system play a key role in the pathogenesis of Parkinson disease. Although the herbicide paraquat is an environmental factor that is involved in the etiology of Parkinson disease, the role of 26S proteasome in paraquat toxicity remains to be determined. Using PC12 cells overexpressing a fluorescent protein fused to the proteasome degradation signal, we report here that paraquat yielded an inhibitory effect on 26S proteasome activity without an obvious decline in 20S proteasome activity. Relative low concentrations of proteasome inhibitors caused the accumulation of nuclear factor erythroid 2-related factor 2 (Nrf2), which is targeted to the ubiquitin-proteasome system, and activated the antioxidant response element (ARE)-dependent transcription. Paraquat also upregulated the protein level of Nrf2 without increased expression of Nrf2 mRNA, and activated the Nrf2-ARE pathway. Consequently, paraquat induced expression of Nrf2-dependent ARE-driven genes, such as γ-glutamylcysteine synthetase, catalase, and hemeoxygenase-1. Knockdown of Nrf2 or inhibition of γ-glutamylcysteine synthetase and catalase exacerbated paraquat-induced toxicity, whereas suppression of hemeoxygenase-1 did not. These data indicate that the compensatory activation of the Nrf2-ARE pathway via inhibition of 26S proteasome serves as part of a cellular defense mechanism to protect against paraquat toxicity.

Endogenous dopamine is involved in the herbicide paraquat-induced dopaminergic cell death.

The herbicide paraquat is an environmental factor that may be involved in the etiology of Parkinson's disease (PD). Systemic exposure of mice to paraquat causes a selective loss of dopaminergic neurons in the substantia nigra pars compacta, although paraquat is not selectively incorporated in dopaminergic neurons. Here, we report a contribution of endogenous dopamine to paraquat-induced dopaminergic cell death. Exposure of PC12 cells to paraquat (50µM) caused delayed toxicity from 36 h onward. A decline in intracellular dopamine content achieved by inhibiting tyrosine hydroxylase (TH), an enzyme for dopamine synthesis, conferred resistance to paraquat toxicity on dopaminergic cells. Paraquat increased the levels of cytosolic and vesicular dopamine, accompanied by transiently increased TH activity. Quinone derived from cytosolic dopamine conjugates with cysteine residues in functional proteins to form quinoproteins. Formation of quinoprotein was transiently increased early during exposure to paraquat. Furthermore, pretreatment with ascorbic acid, which suppressed the elevations of intracellular dopamine and quinoprotein, almost completely prevented paraquat toxicity. These results suggest that the elevation of cytosolic dopamine induced by paraquat participates in the vulnerability of dopaminergic cells to delayed toxicity through the formation of quinoproteins.

Potential protective effect of highly bioavailable curcumin on an oxidative stress model induced by microinjection of sodium nitroprusside in mice brain.

Curcumin, a polyphenolic compound has several pharmacological activities, such as anticancer, anti-inflammatory and antioxidant effects. However, curcumin shows poor oral bioavailability. The purpose of this study was to investigate the protective effects of highly bioavailable curcumin, Theracurmin(®), and curcumin, against sodium nitroprusside (SNP)-induced oxidative damage in mice brain. Intrastriatal microinjection of Theracurmin(®) or curcumin with SNP significantly protected against SNP-induced brain damage and motor dysfunction. Oral administration of Theracurmin(®) (1 and 3 g kg(-1), containing 100 and 300 mg kg(-1) curcumin, respectively) significantly protected against SNP-induced brain damage and motor dysfunction. However, oral administration of 300 mg kg(-1) curcumin did not protect against motor dysfunction induced by SNP. These results suggest that curcumin and Theracurmin(®) have protective effects against SNP-induced oxidative damage. Moreover, oral administration of Theracurmin(®), had more potency in protecting against brain damage, suggesting a higher bioavailability of Theracurmin(®) following oral administration.

Staurosporine induces dopaminergic neurite outgrowth through AMP-activated protein kinase/mammalian target of rapamycin signaling pathway.

Axonal degeneration of dopaminergic neurons is one of the pathological features in the early stages of Parkinson disease. Promotion of axonal outgrowth of the remaining dopaminergic neurons leads to the recovery of the nigrostriatal pathway. Staurosporine (STS), a wide-spectrum kinase inhibitor, induces neurite outgrowth in various cell types, although its mechanism of action remains elusive. In this study, we analyzed which protein kinase is involved in STS-induced neurite outgrowth. We have previously established the method to measure the length of dopaminergic neurites that extend from a mesencephalic cell region, which is formed on a coverslip by an isolation wall. By means of this method, we clarified that STS treatment causes dopaminergic axonal outgrowth in mesencephalic primary cultures. Among the specific protein kinase inhibitors we tested, compound C (C.C), an AMP-activated protein kinase (AMPK) inhibitor, promoted dopaminergic neurite outgrowth. STS as well as C.C elevated the phosphorylation level of 70-kDa ribosomal protein S6 kinase, a downstream target of mammalian target of rapamycin (mTOR) signaling pathway. The STS- and C.C-induced dopaminergic neurite outgrowth was suppressed by rapamycin, an mTOR inhibitor. Furthermore, the application of C.C rescued 1-methyl-4-phenylpyridinium ion (MPP(+))-induced dopaminergic neurite degeneration. These results suggest that STS induces dopaminergic axonal outgrowth through mTOR signaling pathway activation as a consequence of AMPK inhibition.

Neuroprotective effects of curcumin and highly bioavailable curcumin on oxidative stress induced by sodium nitroprusside in rat striatal cell culture.

Curcumin, a polyphenolic compound extracted from Curcuma longa, has several pharmacological activities such as anticancer, anti-inflammatory, and antioxidant effects. The purpose of this study was to investigate the protective effects of curcumin and THERACURMIN, a highly bioavailable curcumin, against sodium nitroprusside (SNP)-induced oxidative damage in primary striatal cell culture. THERACURMIN as well as curcumin significantly prevented SNP-induced cytotoxicity. To elucidate the cytoprotective effects of curcumin and THERACURMIN, we measured the intracellular glutathione level in striatal cells. Curcumin and THERACURMIN significantly elevated the glutathione level, which was decreased by treatment with SNP. Moreover, curcumin showed potent 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical-scavenging ability. Finally, a ferrozine assay showed that curcumin (10-100 µg/mL) has potent Fe(2+)-chelating ability. These results suggest that curcumin and THERACURMIN exert potent protective effects against SNP-induced cytotoxicity by free radical-scavenging and iron-chelating activities.

Protective effect of luteolin on an oxidative-stress model induced by microinjection of sodium nitroprusside in mice.

Accumulating lines of evidence showed that luteolin, a polyphenolic compound, has potent neuroprotective effects. The purpose of this study was to examine whether luteolin can protect against sodium nitroprusside (SNP)-induced oxidative damage in mouse brain. Intrastriatal co-injection of luteolin (3 - 30 nmol) with SNP (10 nmol) dose-dependently protected against brain damage and motor dysfunction. Oral administrations of luteolin (600 - 1200 mg/kg) dose-dependently protected against brain damage and motor dysfunction induced by striatal injection of SNP. Furthermore, luteolin (30 - 100 µM) concentration dependently protected against Fe(2+)-induced lipid peroxidation in mouse brain homogenate. Luteolin (1 - 100 µg/ml) showed potent DPPH radical scavenging ability, when compared with ascorbic acid and glutathione. Finally, a ferrozine assay showed that luteolin (30 - 100 µg/ml) has Fe(2+)-chelating ability, but this was weaker than that of ethylenediaminetetraacetic acid. These results suggest that intrastriatal or oral administration of luteolin protected mice brain from SNP-induced oxidative damage by scavenging and chelating effects.