Protective effects of flavonoids in the roots of Scutellaria baicalensis Georgi against hydrogen peroxide-induced oxidative stress in HS-SY5Y cells

Baicalein-induced apoptosis via endoplasmic reticulum stress through elevations of reactive oxygen species and mitochondria dependent pathway in mouse-rat hybrid retina ganglion cells (N18)

Studies were designed to investigate the effects of baicalein on mouse-rat hybrid retina ganglion cells (N18) to better understand its effect on apoptosis and apoptosis-related genes in vitro. Cell viability, reactive oxygen species (ROS), cytoplasmic Ca2+, mitochondrial membrane potential (MMP), apoptosis induction, and caspases-3 activity were examined by flow cytometric assay. Apoptosis-associated proteins such as p53, Bax, Bcl-2, cytochrome c, and caspase-3 were examined by Western blot. We demonstrated the increase in the levels of p53, Bax, and cytochrome c and decrease in the level of Bcl-2, which are associated with the induction of apoptotic cell death after 24 h treatment with baicalein in N18 cells. Baicalein induced an increase in the cytoplasmic levels of ROS and Ca2+ in 1 h and reached their peak at 3 h, and thereafter a loss of MMP by flow cytometry. We also demonstrated a release of the cytochrome c from mitochondria into cytosol and an activation of caspase-3, which led to the occurrence of apoptosis in N18 cells treated with baicalein by Western blot. Pretreatment was conducted with BAPTA (intracellular calcium chelator) in baicalein-treated cells, the decline of MMP was recovered, and the increase in the level of cytoplasmic Ca2+ was suppressed, and the proportion of apoptosis was also markedly diminished. In conclusion, our data suggests that oxidative stress and cellular Ca2+ modulates the baicalein-induced cell death via a Ca2+-dependent mitochondrial death pathway in N18 cells.

Ceramide elevates 12-hydroxyeicosatetraenoic acid levels and upregulates 12-lipoxygenase in rat primary hippocampal cell cultures containing predominantly astrocytes

We report, exogenous addition of ceramide significantly increases 12-hydroxyeicosatetraenoic acid [12-(S)-HETE] levels, in a dose-dependent manner. 12-(S)-HETE levels, in 20, 30 and 40microM ceramide exposed rat primary hippocampal cell cultures containing predominantly astrocytes and few neurons and other glial cells (the cultured hippocampal cells were predominantly astrocytes amounting to over 99% of total cells with few neurons and other glial cells) amounted to 207, 260 and 408% of the controls, respectively. However, dihydroceramide, an inactive analog of ceramide did not alter the levels of 12-(S)-HETE. Ceramide also increased the mRNA and protein expression, and activity of 12-lipoxygease (12-LOX) needed for the synthesis of 12(S)-HETE. These results indicate a possible link between ceramide and 12-LOX pathway. However, ceramide did not alter expression of 5-lipoxygenase (5-LOX), another member of the lipoxygenase family. However, ceramide upregulated expression of cytosolic phospholipase-A(2) (cPLA(2)) and cyclooxygenase-2 (COX-2). Further, ceramide caused a significant increase in the levels of reactive oxygen species (ROS). Ceramide-mediated generation of ROS was inhibited by baicalien but not by indomethacin. In addition, ceramide treated cells exhibited increased mRNA expression of DNA damage induced transcript3 (Ddit3). This report which demonstrate induction of pro-carcinogenic 12-LOX pathway by an anticancer ceramide, may be relevant to cancer biologists studying drug resistant tumors and devising potent anticancer therapeutic strategies to treat drug resistant tumors. These results indicate possibility of 12-LOX involvement in ceramide-mediated generation of ROS and cellular oxidative stress. Induction of 12-LOX pathway by ceramide may have implications in understanding pathophysiology of neurodegenerative diseases involving ROS generation and inflammation.

Protective effect of quercetin in primary neurons against Abeta(1-42): relevance to Alzheimer's disease

Quercetin, a flavonoid found in various foodstuffs, has antioxidant properties and increases glutathione (GSH) levels and antioxidant enzyme function. Considerable attention has been focused on increasing the intracellular GSH levels in many diseases, including Alzheimer's disease (AD). Amyloid beta-peptide [Abeta(1-42)], elevated in AD brain, is associated with oxidative stress and neurotoxicity. We aimed to investigate the protective effects of quercetin on Abeta(1-42)-induced oxidative cell toxicity in cultured neurons in the present study. Decreased cell survival in neuronal cultures treated with Abeta(1-42) correlated with increased free radical production measured by dichlorofluorescein fluorescence and an increase in protein oxidation (protein carbonyl, 3-nitrotyrosine) and lipid peroxidation (protein-bound 4-hydroxy-2-nonenal). Pretreatment of primary hippocampal cultures with quercetin significantly attenuated Abeta(1-42)-induced cytotoxicity, protein oxidation, lipid peroxidation and apoptosis. A dose-response study suggested that quercetin showed protective effects against Abeta(1-42) toxicity by modulating oxidative stress at lower doses, but higher doses were not only non-neuroprotective but also toxic. These findings provide motivation to test the hypothesis that quercetin may provide a promising approach for the treatment of AD and other oxidative-stress-related neurodegenerative diseases.

Synthesis and biological evaluation of novel C(6) modified baicalein derivatives as antioxidative agents

Baicalein, one of the major flavones, was found to be responsible for the antioxidative activity of the traditional Chinese medicinal herb Huang-Qin ( Scutellaria baicalensis Georgi), which is widely used as an antioxidative, anti-inflammatory, and antitumor agent. The hydroxyl group of the A ring of the baicalein was alkylated at position 6 with terpenoids such as prenyl, geranyl, and farnesyl groups, and their free radical scavenging activities and glutathione (GSH) depletion capacities were examined. Their free radical scavenging activity was measured according to the 2,2'-azinobis(3-ethylbenzothiazoline-6-sulfonic acid) (ABTS(*+)) scavenging method. Baicalein and newly synthesized baicalein derivatives were found to be good free radical scavengers. Flow cytometrical method was employed to measure the intracellular antioxidative activity and GSH depletion capacity of these derivatives in human acute monocytic leukemia cell line (THP-1). It was also found that baicalein and its derivatives could decrease the levels of exogenous cumene hydroperoxide and H2O2 in THP-1 cells. These compounds also could significantly inhibit the intracellular GSH depletion induced by cumene hydroperoxide in THP-1 cells. The production of cumene hydroperoxide-induced Bax, a pro-apoptotic related protein, could also be inhibited by baicalein and its derivatives. These results suggested that baicalein and its derivatives could be beneficial to human health.

12-o-Tetradecanoylphorbol 13-acetate prevents baicalein-induced apoptosis via activation of protein kinase C and JNKs in human leukemia cells

In the present study, we found that baicalein (BE), but not its glycoside baicalin (BI), induced apoptosis in human leukemia HL-60 and Jurkat cells, but not in primary murine peritoneal macrophages (PMs) or human polymorphonuclear (PMN) cells, by the MTT assay, LDH release assay, and flow cytometric analysis. Activation of the caspase 3, but not caspase 1, enzyme via inducing protein processing was detected in BE-induced apoptosis. The ROS-scavenging activity of BE was identified by the anti-DPPH radical, DCHF-DA, and in vitro plasmid digestion assay, and none of chemical antioxidants including allpurinol (ALL), N-acetyl-cystein (NAC), and diphenylene iodonium (DPI) affected BE-induced apoptosis in HL-60 cells. This suggests that apoptosis induced by BE is independent of the production of ROS in HL-60 cells. Interestingly, the apoptotic events such as DNA ladders formation and activation of the caspase 3 cascade were significantly blocked by TPA addition in the presence of membrane translocation of PKCalpha, and TPA-induced protection was reduced by adding the PKC inhibitors, GF-109203X and staurosporin. TPA addition induces the phosphorylation of JNKs and ERKs, but not p38, protein in HL-60 cells, and incubation of HL-60 cells with JNKs inhibitor SP600125, but not ERKs inhibitor, PD98059 or the p38 inhibitor SB203580, suppressed the protective effect of TPA against BE-induced apoptotic events including DNA ladders, apoptotic bodies, caspase 3 and D4-GDI protein cleavage in according with blocking JNKs protein phosphorylation. In addition, PKC inhibitor GF-109203X treatment blocks TPA-induced ERKs and JNKs protein phosphorylation, which indicates that activation of PKC locates at upstream of MAPKs activation in TPA-treated HL-60 cells. Additionally, a loss in mitochondrial membrane potential with a reduction in Bcl-2 protein expression, the induction of Bad protein phosphorylation, and translocation of cytochrome c from mitochondria to the cytosol were observed in BE-treated HL-60 cells, and these events were prevented by the addition of TPA. GF-109203X and SP600125 suppression of TPA against cytochrome c release induced by BE was identified. This suggests that activation of PKC and JNKs participate in TPA's prevention of BE-induced apoptosis via suppressing mitochondrial dysfunction in HL-60 cells.

Antioxidant activity of N-acetylcysteine, flavonoids and α-tocopherol on endometrial cells in culture

An appropriate local environment is necessary for successful implantation. Oxidative stress is implicated in the pathogenesis of several pathologies, and may contribute to early pregnancy failure. Antioxidant therapies have been studied in infertility. In this study, we have assessed the antioxidant activity of N-acetylcysteine (NAC), flavonoids (quercetin, catechin) and alpha-tocopherol in an oxidative model of endometrial cells (RL95). Endometrial cells were incubated at several hydrogen peroxide concentrations. Antioxidant effects of NAC (15 mM), quercetin (150 microM), catechin (150 microM) and alpha-tocopherol included in liposomes (1.6 microg) were assessed by measuring cell viability by the MTT assay. Alpha-tocopherol-liposomes taken up by endometrial cells were assessed by HPLC. All liposomes used were able to introduce alpha-tocopherol into cells. The antioxidant effect of NAC and quercetin improved the viability of oxidised cells, and this effect was observed when the oxidant and antioxidant were coincubated. No viability change occurred when the antioxidant was added before or after the oxidant. The antioxidant effect of NAC was better than that of quercetin. When catechin or alpha-tocopherol were used in the same conditions, no antioxidant effect was detected in cells in culture. These results demonstrate that NAC and quercetin are good H2O2 scavengers.

Neuropathology, biochemistry, and biophysics of alpha-synuclein aggregation

Aggregation of alpha-synuclein, an abundant and conserved pre-synaptic brain protein, is implicated as a critical factor in several neurodegenerative diseases. These diseases, known as synucleinopathies, include Parkinson's disease, dementia with Lewy bodies (LBs), diffuse LB disease, the LB variant of Alzheimer's disease, multiple system atrophy, and neurodegeneration with brain iron accumulation type I. Although the precise nature of in vivoalpha-synuclein function remains elusive, considerable knowledge has been accumulated about its structural properties and conformational behavior. alpha-Synuclein is a typical natively unfolded protein. It is characterized by the lack of rigid, well-defined, 3-D structure and possesses remarkable conformational plasticity. The structure of this protein depends dramatically on its environment and it accommodates a number of unrelated conformations. This paper provides an overview of the biochemistry, biophysics, and neuropathology of alpha-synuclein aggregation.

Fluoride-induced oxidative stress of osteoblasts and protective effects of baicalein against fluoride toxicity

The key role of osteoblasts in skeletal fluorosis makes the exploration of the possible mechanisms of the fluoride-induced oxidative stress of osteoblasts of great importance. In this article, the in vitro effects of fluoride on the oxidative stress of osteoblasts are presented. To study the inhibitory effect of baicalein on the oxidative stress of osteoblasts, the antioxidant activity of baicalein was evaluated for osteoblasts exposed to fluoride. Calvarial osteoblasts were prepared and respectively treated with alpha-MEM (5% calf serum) containing 0.5, 1.0, 2.0, 4.0, 8.0, 12.0, and 20.0 mg/L fluoride for 48 h. Baicalein (10 micromol/L) was added to the cells for the same period of time as that of the fluoride treatment. Low concentrations of fluoride (0.5-2 mg F-/L) stimulated the mitochondrial activity of osteoblasts and produced significant reaction to the oxidative stress, whereas high concentrations of fluoride (>or=12 mg F-/L) inhibited cell proliferation and the activity of antioxidant enzymes. This suggests that the oxidative stress induced by low concentrations of fluoride might mediate or participate in the process of fluoride inducing the proliferation of osteoblasts. The viability of osteoblasts in the high concentrations of fluoride with the addition of 10 mumol/L baicalein (>or=12 mg/L) was higher than those of the same level of fluoride- treated groups without the addition of baicalein. The protective role of baicalein is obvious as an inhibitor of lipid peroxidation against the damage induced by the high concentration of fluoride.

Neuroglobin and cytoglobin overexpression protects human SH-SY5Y neuroblastoma cells against oxidative stress-induced cell death

Although reactive oxygen species (ROS) at physiological concentrations are required for normal cell function, excessive production of ROS is detrimental to cells. Neuroglobin and cytoglobin are two globins, whose functions are still a matter of debate. A potential role in the detoxification of ROS is suggested. The influence of neuroglobin and cytoglobin on cell death after oxidative stress in human neuroblastoma SH-SY5Y cells was evaluated. Exposure of SH-SY5Y cells to paraquat or H(2)O(2) resulted in a concentration- and time-dependent induction of apoptotic and necrotic cell death. H(2)O(2) was 16 times more potent to induce cell death as compared to paraquat. SH-SY5Y cells transfected with plasmid DNA containing the neuroglobin or cytoglobin sequence showed enhanced survival after exposure to 300 microM H(2)O(2) for 24h as compared to untransfected controls. This finding suggests that neuroglobin and cytoglobin protect SH-SY5Y cells against oxidative stress-induced cell death.

Recent applications of liquid chromatography-mass spectrometry in natural products bioanalysis

Natural flavonoids, alkaloids, saponins and sesquiterpenoids have been extensively investigated because of their biological and physiological significances, as well as their promising clinical uses. It is necessary to monitor them or their metabolites in biological fluids for both pre-clinical studies and routine clinical uses. The successful hyphenation of LC and MS, which was thought as "the bird wants to marry with fish", has been conducted widely in biological samples analysis. This present paper reviewed the feasibility of LC-MS techniques in the identification and quantification of natural products (flavonoids, alkaloids, saponins and sesquiterpenoids) in biological fluids, dealing with sample preparation, LC techniques, suitability of different MS techniques. Perspective of LC-MS was also discussed to show the potential of this technology. The citations cover the period 2002-2006. We conclude that LC-MS is an extremely powerful tool for the analysis of natural products in biological samples.

Difference of growth-inhibitory effect of Scutellaria baicalensis-producing flavonoid wogonin among human cancer cells and normal diploid cell

Methanol extract from cultured Scutellaria baicalensis cells inhibited the proliferation of human monocytic leukemia cell line THP-1 and human osteogenic sarcoma cell line HOS. The inhibitory effects of baicalin, baicalein and wogonin, the three major flavonoids contained in the extract, were studied. It should be noted that wogonin did not show the inhibitory effect on human fetal lung normal diploid cell line TIG-1, as compared to the inhibition observed in cancer cells. Physiological analyses in THP-1 cells showed that wogonin induced cell cycle arrest at G(2)/M phase and apoptosis. This is the first report discovering a cancer-specific apoptosis-inducing activity of wogonin.

Ondamtanggamibang protects neurons from oxidative stress with induction of heme oxygenase-1

Ondamtanggamibang (ODG) has been used as a remedy to treat psychological anxiety and depression in Oriental medicine. In this study, we found the protective effects of ODG against oxidative stress by induction of the antioxidative enzyme, heme oxygenase (HO)-1 in neuronal PC12 cells. Pretreatment with ODG extract protected neuronal cells from damage induced by H(2)O(2) and 6-hydroxydopamine (6-OHDA), but simultaneous treatment with ODG extract did not. ODG also inhibited the intracellular reactive oxygen species elevation by H(2)O(2) and 6-OHDA. ODG stimulation strongly induced the expression of HO-1 in PC12 cells. The protective effect of ODG extract on oxidative stress-induced damage was suppressed by HO inhibitor, zinc protoporphyrin IX (ZnPP-IX). Taken together, these data suggest that ODG treatment has potential protective effects in neuronal cells under oxidative stress.

A comparative study on the individual and combined effects of baicalin and jasminoidin on focal cerebral ischemia-reperfusion injury

To compare the individual effects of baicalin and jasminoidin with the combined effect of them on cerebral ischemia-reperfusion injury, and test whether the combined administration of baicalin and jasminoidin can improve the therapeutic effect. Male Sprague-Dawley rats underwent focal cerebral ischemia for 1.5 h and reperfusion for 24 h. Just before reperfusion, tested drugs (baicalin, jasminoidin, a drug combination consisting of baicalin and jasminoidin, or nimodipine) were intravenously treated. Diffusion weighted imaging (DWI) of magnetic resonance imaging (MRI), behavior examination, 2,3,5-triphenyltetrazolium chloride (TTC) staining, histological examination, and real-time PCR for BDNF and caspase-3 were performed. All of the drug treatments could significantly ameliorate the results of TTC and histological examination, and the baicalin/jasminoidin combination did so most prominently. This combination could also significantly ameliorate DWI of MRI and behavior examination results, and promote the expression of BDNF and inhibit the expression of caspase-3. On the whole, both baicalin and jasminoidin have a preventive effect against ischemic stroke, although their effects are not very strong. However, the combination of baicalin and jasminoidin can significantly improve their effectiveness. This may be related to its better regulation on the BDNF and caspase-3.

The effects of the flavonoid baicalein and osmolytes on the Mg 2+ accelerated aggregation/fibrillation of carboxymethylated bovine 1SS-α-lactalbumin

Many protein conformational diseases arise when proteins form alternative stable conformations, resulting in aggregation and accumulation of the protein as fibrillar deposits, or amyloids. Interestingly, numerous proteins implicated in amyloid protein formation show similar structural and functional properties. Given this similarity, we tested the notion that carboxymethylated bovine alpha-lactalbumin (1SS-alpha-lac) could serve as a general amyloid fibrillation/aggregation model system. Like most amyloid forming systems, Mg2+ ions accelerate 1SS-alpha-lac amyloid fibril formation. While osmolytes such as trimethylamine N-oxide (TMAO), and sucrose enhanced thioflavin T detected aggregation, a mixture of trehalose and TMAO substantially inhibited aggregation. Most importantly however, the flavonoid, baicalein, known to inhibit alpha-synuclein amyloid fibril formation, also inhibits 1SS-alpha-lac amyloid with the same apparent efficacy. These data suggest that the easily obtainable 1SS-alpha-lac protein can serve as a general amyloid model and that some small molecule amyloid inhibitors may function successfully with many different amyloid systems.

Protective effect of Rosa laevigata against amyloid beta peptide-induced oxidative stress

The amyloid beta (Abeta) peptide is known to increase free radical production in nerve cells, leading to cell death. To investigate the effect of Rosa laevigata against Abeta-induced oxidative damage, in vitro assays and in vivo behavioral tests were performed. R. laevigata showed cell protective effects against oxidative stress-induced cytotoxicity. MTT (3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide) reduction assay exhibited significant increase in cell viability when rat pheochromocytoma (PC 12) cells were treated with R. laevigata extracts. Administration of R. laevigata extracts to mice significantly reversed the Abeta-induced learning and memory impairment in in vivo behavioral tests. These results suggest that R. laevigata extracts can reduce the cytotoxicity of Abeta in PC 12 cells, possibly by the reduction of oxidative stress, and these extracts may be useful in the prevention of Alzheimer's disease.

Preparation, characterization and in vivo evaluation of formulation of baicalein with hydroxypropyl-beta-cyclodextrin

The interaction of 2-hydroxypropyl-beta-cyclodextrin (HP-beta-CD) and a poorly water-soluble flavonoid, baicalein (Ba), chemically 5,6,7-trihydroxy flavone in solution and solid-state was studied. Ba/HP-beta-CD solid systems were prepared by freeze-drying method. The formation of Ba/HP-beta-CD complex in aqueous solution was demonstrated by UV spectroscopy, while Ba/HP-beta-CD co-lyophilized product was characterized by differential scanning calorimetry (DSC) and X-ray diffractometry (XRD). Through complexation with HP-beta-CD, the solubility of Ba in neutral aqueous solution was improved significantly. The phase-solubility profile was AP-type, indicating the formation of higher-order complexes or complex aggregates. Ba/HP-beta-CD solid powders were amorphous and show a significantly improved dissolution rate in comparison with free Ba. Comparison of the pharmacokinetics between Ba/HP-beta-CD co-lyophilized product and free Ba was also performed in rats. The concentration of Ba and its mainly conjugated metabolite, 7-O-glucuronide of baicalein (BG) in rat plasma was determined by HPLC method. The in vivo results show that Ba/HP-beta-CD co-lyophilized product exhibits the similar pharmacokinetics as that of free Ba after intravenous administration. Ba/HP-beta-CD co-lyophilized product displays earlier tmax and higher Cmax of BG than free Ba after oral dosing. By comparing the AUC0-infinity of BG between oral dosing, the relative bioavailability of Ba/HP-beta-CD co-lyophilized product to free Ba was 165.0%, which highlighted the evidence of significantly improved bioavailability of formulation of Ba with HP-beta-CD.

The Anticancer Activities of Wogonin in Murine Sarcoma S180 both in Vitro and in Vivo

The anticancer effects of wogonin on murine sarcoma S180 both in vitro and in vivo were investigated, and its pro-apoptotic molecular mechanism was further studied. Wogonin treatment resulted in significant inhibition of S180 cells in a concentration-dependent manner detected by MTT assay. The IC50 value for 48 h was (7.37+/-1.53) x 10(-5) M. Typical morphological changes and apoptosis bleb phenomenon in S180 cells exposed to wogonin were distinctly observed by the inverted light microscope and the fluorescence microscope, respectively. According to protocols of transplanted tumor research, mice were transplanted with tumor cells S180. The weight of tumor and the peripheral leucocyte count were observed after the treatment of wogonin. The significant suppression of tumor growth was observed, and the peripheral leucocyte count of S180-bearing mice remained no significant changes compared with control group. After the treatment of 40 mg/kg wogonin, the inhibitory rate of tumor weight was 53.01%. Additional DNA fragmentation assay showed that wogonin induced apoptosis on murine sarcoma S180 tissue. RT-PCR results indicated that the increasing mRNA levels of bax and p53 and the decreasing mRNA level of bcl-2 were induced by wogonin. Western-blot assay showed that the increasing protein level of bax and the decreasing protein level of bcl-2 were induced by wogonin. Collectively, wogonin could induce apoptosis in murine sarcoma S180 thereby inhibiting the tumor growth both in vitro and in vivo. The pro-apoptotic effects might be related to the improvement of mRNA level of p53, the improvement of mRNA and protein levels of bax, and the reduction of mRNA and protein levels of bcl-2.

Therapeutic potential of wogonin: a naturally occurring flavonoid

The search for flavonoids with novel therapeutic effects has been intense. Wogonin, as a naturally existing monoflavonoid, has been shown to have therapeutic potential in vitro and in vivo. Methods for its extraction from herbs and its chemical synthesis have been developed. Pharmacokinetic studies have shown a rapid tissue distribution and prolonged plasma elimination phase of wogonin. It has been shown experimentally that wogonin exerts anti-oxidant activity, which may, in part, underlie its antiinflammatory, anti-cancer, antiviral and neuroprotective actions. The recent discovery of its anxiolytic activity suggests a new mechanism of action, involving interaction with the benzodiazepine (BZD) binding site of the GABA(A) receptor and modulation of this receptor activity. Although the safety record of wogonin is remarkable and voluminous literature about its pharmacological effects is available, it has not been used in Western medicine in the form of a pure chemical. In this article we review its therapeutic effects, its sources and pharmacokinetic profile to highlight its therapeutic potential.

Neuroprotective herbs for stroke therapy in traditional eastern medicine

Traditional Eastern Medicine (TEM) has a long history in stroke therapy and its therapeutic efficacy has been confirmed by clinical studies. Extensive experience and abundant clinical data on TEM in stroke treatment have been accumulated over the past thousand years. Basic and clinical research in TEM constitutes a potentially rich source for new drug discovery and development with the integration of TEM and Western pharmacology. In recent years, many attempts have been made to document research data from extracts of composite formulas, single herbs, or single compounds from TEM herbs, according to orthodox pharmacological actions. This article reviews herbs and prescriptions that have been documented to have a neuroprotective effect in in vitro and in vivo ischemic model systems, and the neuroprotective compounds isolated from them. I also discuss the neuroprotective mechanisms of prescriptions, herbs, and single compounds relevant to the treatment of brain ischemia, including anti-oxidant, anti-excitotoxic, and anti-inflammatory effects.

Regulation of Neuroinflammation by Herbal Medicine and Its Implications for Neurodegenerative Diseases

Herbal medicine has long been used to treat neural symptoms. Although the precise mechanisms of action of herbal drugs have yet to be determined, some of them have been shown to exert anti-inflammatory and/or anti-oxidant effects in a variety of peripheral systems. Now, as increasing evidence indicates that neuroglia-derived chronic inflammatory responses play a pathological role in the central nervous system, anti-inflammatory herbal medicine and its constituents are being proved to be a potent neuroprotector against various brain pathologies. Structural diversity of medicinal herbs makes them valuable source of novel lead compounds against therapeutic targets that are newly discovered by genomics, proteomics, and high-throughput screening.

Synthetic wogonin derivatives suppress lipopolysaccharide-induced nitric oxide production and hydrogen peroxide-induced cytotoxicity

Wogonin (5,7-dihydroxy-8-methoxyflavone) has been reported to exhibit a variety of biological properties including anti-inflammatory and neuroprotective functions. In this study, biological activities of diverse synthetic wogonin derivatives have been evaluated in two experimental cell culture models. Inhibitory activities of wogonin derivatives on lipopolysaccharide (LPS)-induced nitric oxide (NO) production in BV2 microglial cells and on hydrogen peroxide (H2O2)-induced neuronal cell death in SH-SY5Y human neuroblastoma were examined. Wogonin derivatives such as WS2 and WS3 showed more potent suppressive activities on LPS-induced NO production and H2O2-induced cytotoxicity than wogonin itself. In addition, thiol substitution played a minor role in enhancing the activities of the derivatives. These findings may contribute to the development of novel anti-inflammatory and neuroprotective agents derived from wogonin.

Baicalein Prevents 6-Hydroxydopamine-Induced Dopaminergic Dysfunction and Lipid Peroxidation in Mice

The effects of baicalein on 6-hydroxydopamine (6-OHDA)-induced neurotoxicity were evaluated. Intracerebroventricularly (i.c.v.) injection of 6-OHDA was done to young mice. Baicalein was administered intraperitoneally 30 min before and 90 min after i.c.v. injection. Animals received further injection of bacalein daily for 3 consecutive days. Rotarod performance was assessed, tyrosine hydroxylase (TH) Western blotting was performed, and dopamine (DA) levels and peroxidation were determined. High dose of baicalein effectively improved rotarod performance and prevented the reduction of striatal DA levels and TH contents in the striatum and subtantia nigra (SN). In addition, lipid peroxidation level was decreased by baicalein at 3 and 7 days after 6-OHDA injection. These results showed that baicalein effectively prevents the 6-OHDA-induced dopaminergic dysfunction through an antioxidative action.

Separation methods used for Scutellaria baicalensis active components

Scutellaria baicalensis Georgi is one of the most widely used traditional Chinese herbal medicines. Its roots have been used for anti-inflammation, anticancer, antiviral and antibacterial infections of the respiratory and the gastrointestinal tract, cleaning away heat, moistening aridity, purging fire, detoxifying toxicosis, reducing the total cholesterol level and decreasing blood pressures. Baicalin, baicalein, wogonin and oroxylin A are its main active components. This review provides an overview of various separation, detection, and identification techniques employed for the quantitative and qualitative determination of these active components. Applications of high-performance liquid chromatography, high-speed counter-current chromatography, thin layer chromatography, capillary electrophoresis, and micellar electrokinetic capillary chromatography to the separation and determination of these active components are described. Examples of identification of these active components and their metabolites in complex matrices by high-performance liquid chromatography-mass spectrometry and gas chromatography-mass spectrometry are also presented. The advantages and limitations of these separation and identification methods are assessed and discussed.

Hemin/nitrite/H2O2 induces brain homogenate oxidation and nitration: effects of some flavonoids

Oxidative injury has been implicated in the pathogenesis of numerous neurodegenerative diseases. Recently, it has been found that with the existence of hydrogen peroxide and nitrite, hemin catalyzes protein nitration. We hypothesize under certain pathological conditions, hemin catalyzed protein nitration may happen in the brain. In this paper, the effects of three flavonoids, i.e. quercetin, catachin and baicalein on hemin/nitrite/H2O2 induced brain homogenate oxidation and nitration were studied. The results showed that hemin/nitrite/H2O2 system could effectively induce brain homogenate protein oxidation and nitration. Quercetin, catachin and baicalein dose-dependently inhibited hemin/nitrite/H2O2 system-induced protein nitration in a dose-dependent manner, the inhibition of protein nitration was in the order of quercetin>catachin>baicalein. These compounds also inhibited hemin/H2O2 system-induced lipid peroxidation, the inhibition order was baicalein >quercetin>catachin. However, these flavonoids showed marginal effect on hemin/nitrite/H2O2 system caused protein oxidation and thiol oxidation. The inhibition activities of flavonoids on hemin/nitrite/H2O2 system-induced protein nitration may closely relate to their radical scavenging activities, since the inhibition order of protein nitration is the same as the radical scavenging order. These results indicate hemin/nitrite/H2O2 system induces different types of oxidative assault on bio-molecules. Flavonoids could act as antioxidants inhibiting ROS and RNS caused brain damage.

Activation of ERK1/2, JNK and PKB by hydrogen peroxide in human SH-SY5Y neuroblastoma cells: role of ERK1/2 in H2O2-induced cell death

Reactive oxygen species including H(2)O(2) activate an array of intracellular signalling cascades that are closely associated with cell death and cell survival pathways. The human neuroblastoma SH-SY5Y cell line is widely used as model cell system for studying neuronal cell death induced by oxidative stress. However, at present very little is known about the signalling pathways activated by H(2)O(2) in SH-SY5Y cells. Therefore, in this study we have investigated the effect of H(2)O(2) on extracellular signal-regulated kinase 1/2 (ERK1/2), c-Jun N-terminal kinase (JNK), p38 mitogen-activated protein kinase (p38 MAPK) and protein kinase B (PKB) activation in undifferentiated and differentiated SH-SY5Y cells. H(2)O(2) stimulated time and concentration increases in ERK1/2, JNK and PKB phosphorylation in undifferentiated and differentiated SH-SY5Y cells. No increases in p38 MAPK phosphorylation were observed following H(2)O(2) treatment. The phosphatidylinositol 3-kinase (PI-3K) inhibitors wortmannin and LY 294002 ((2-(4-morpholinyl)-8-phenyl-4H-1-benzopyran-4-one) inhibited H(2)O(2)-induced increases in ERK1/2 and PKB phosphorylation. Furthermore, H(2)O(2)-mediated increases in ERK1/2 activation were sensitive to the MAPK kinase 1 (MEK1) inhibitor PD 98059 (2'-amino-3'-methoxyflavone), whereas JNK responses were blocked by the JNK inhibitor SP 600125 (anthra[1-9-cd]pyrazol-6(2H)-one). Treatment of SH-SY5Y cells with H(2)O(2) (1 mM; 16 h) significantly increased the release of lactate dehydrogenase (LDH) into the culture medium indicative of a decrease in cell viability. Pre-treatment with wortmannin, SP 600125 or SB 203580 (4-(4-fluorophenyl)-2-(4-methylsulfinylphenyl)-5-(4-pyridyl)1H-imidazole; p38 MAPK inhibitor) had no effect on H(2)O(2)-induced LDH release from undifferentiated or differentiated SH-SY5Y cells. In contrast, PD 98059 and LY 294002 significantly decreased H(2)O(2)-induced cell death in both undifferentiated and differentiated SH-SY5Y cells. In conclusion, we have shown that H(2)O(2) stimulates robust increases in ERK1/2, JNK and PKB in undifferentiated and differentiated SH-SY5Y cells. Furthermore, the data presented clearly suggest that inhibition of the ERK1/2 pathway protects SH-SY5Y cells from H(2)O(2)-induced cell death.

Neuroprotective effect of fraxetin and myricetin against rotenone-induced apoptosis in neuroblastoma cells

Rotenone-induced apoptosis is considered to contribute to the etiology of Parkinson's disease (PD). We try to prevent the apoptosis induced by rotenone toxicity with 50 microM myricetin, 100 microM fraxetin and 100 microM N-acetylcysteine (NAC) that protect against reactive oxygen species (ROS), on SH-SY5Y human neuroblastoma cell line. Morphological changes induced by rotenone and intracellular ROS were assessed in live SH-SY5Y dopaminergic cells by confocal microscopy using the fluorescent dyes, dihydroethidium and 2',7'-dichlorofluorescein diacetate (DCFH-DA). DNA fragmentation was assayed as index of apoptosis. We also investigated oxidative stress parameters such as the glutathione redox status and lipid peroxidation. The exposure of the SH-SY5Y cells to rotenone 5 microM for 16 h produced severe morphological changes, DNA fragmentation and significative increases in the levels of hydrogen peroxide and superoxide anion. These increases were reduced by a 30-min pretreatment with fraxetin 100 microM or NAC 100 microM. DNA laddering produced by rotenone treatment was also inhibited by fraxetin and NAC. Treatment with 5 microM rotenone induced loss of reduced glutathione (GSH) and increased cellular levels of oxidized glutathione (GSSG). Fraxetin and NAC treatments restored glutathione redox ratio diminished after rotenone challenge and decreased the levels of lipid peroxidation. These results suggest that the natural antioxidants, such as fraxetin, may prevent the apoptotic death of dopaminergic cells induced by rotenone and mediated by oxidative stress.

The flavonoid baicalein inhibits fibrillation of alpha-synuclein and disaggregates existing fibrils

The aggregation of alpha-synuclein has been implicated as a critical step in the development of Parkinson's disease. Parkinson's disease is a progressive neurodegenerative disorder caused by the loss of dopaminergic neurons from the substantia nigra; currently, no cure exists. Baicalein is a flavonoid with antioxidant properties; upon oxidation, it forms several products including quinones. We show here that low micromolar concentrations of baicalein, and especially its oxidized forms, inhibit the formation of alpha-synuclein fibrils. In addition, existing fibrils of alpha-synuclein are disaggregated by baicalein. The product of the inhibition reaction is predominantly a soluble oligomer of alpha-synuclein, in which the protein molecules have been covalently modified by baicalein quinone to form a Schiff base with a lysine side chain in alpha-synuclein. The binding of baicalein was abolished by conversion of the Tyr residues into Phe, demonstrating that Tyr is involved in the interaction of alpha-synuclein with baicalein. In disaggregation baicalein causes fragmentation throughout the length of the fibril. These observations suggest that baicalein and similar compounds may have potential as therapeutic leads in combating Parkinson's disease and that diets rich in flavonoids may be effective in preventing the disorder.

Wogonin inhibits excitotoxic and oxidative neuronal damage in primary cultured rat cortical cells

The present study evaluated effects of wogonin (5,7-dihydroxy-8-methoxyflavone) on excitotoxic and oxidative stress-induced neuronal damage in primary cultured rat cortical cells. Wogonin was shown to inhibit the excitotoxicity induced by glutamate or N-methyl-D-aspartic acid, whereas it showed no effects on the alpha-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid- or kainate-induced toxicity. In addition, wogonin inhibited the oxidative neuronal damage induced by H(2)O(2), xanthine/xanthine oxidase, and by a glutathione depleting agent D,L-buthionine [S,R]-sulfoximine. Furthermore, wogonin dramatically inhibited lipid peroxidation initiated by Fe(2+) and L-ascorbic acid in rat brain homogenates. It also exhibited 1,1-diphenyl-2-picrylhydrazyl radical scavenging activity. Taken together, these results demonstrate that wogonin exhibits neuroprotective actions in cultured cortical cells by inhibiting excitotoxicity and various types of oxidative stress-induced damage, and that its antioxidant actions with radical scavenging activity may contribute, at least in part, to the neuroprotective effects.

Wogonin Inhibits Ischemic Brain Injury in a Rat Model of Permanent Middle Cerebral Artery Occlusion

The present study evaluated the effect of wogonin, a flavonoid originated from the root of Scutellaria baicalensis GEORGI, on focal ischemic brain injury in rats. Focal brain ischemia was induced by the permanent occlusion of middle cerebral artery (pMCAO) for 24 h with a silicone rubber cylinder inserted through the right internal carotid artery. We found that wogonin, intraperitoneally administered at a dosage of 20 mg/kg at 30 min before and 4 h after the surgery, reduced the pMCAO-induced infarct areas in the cerebral cortex as well as in the striatum. The total volume of infarction was significantly reduced by the treatment with wogonin. In addition, wogonin was found to significantly improve the pMCAO-induced behavioral deficits at 24 h after the surgery. Taken together, these results demonstrate that wogonin inhibits ischemic brain injury and improves behavioral dysfunction caused by pMCAO. These findings, along with previous reports demonstrating the neuroprotective effects of wogonin, provide strong pharmacological basis for the use of wogonin or Scutellaria baicalensis in the treatment of stroke.

Differential effects of natural polyphenols on neuronal survival in primary cultured central neurons against glutamate- and glucose deprivation-induced neuronal death

Neuronal injury in the central nervous system following ischemic insult is believed to result from glutamate toxicity and glucose deprivation. In this study, polyphenols isolated from Scutellaria baicalensis Georgi, including baicalin, baicalein, and wogonin, were investigated for their neuroprotective effects against glutamate/NMDA (Glu/NMDA) stimulation and glucose deprivation in primary cultured rat brain neurons. Cell death was accessed by lactate dehydrogenase (LDH) release assay for necrosis, and mitochondrial activity was accessed by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide (MTT) reduction activity assay. It was found that both baicalin and baicalein decreased LDH release of the cultured neurons after 24 h treatment, whereas wogonin profoundly increased LDH release after 2 h treatment and resulted in neuronal death after 24 h. Glu/NMDA treatment profoundly increased LDH release and moderately decreased MTT reduction activity in an NMDA receptor-dependent manner. Both baicalin and baicalein significantly reduced Glu/NMDA-increased LDH release, in which baicalein is much more potent than baicalin. Glu/NMDA-increased intracellular calcium was also significantly attenuated by baicalin and baicalein. Baicalin and baicalein did not affect glutamate receptor binding activity, but baicalein did moderately decrease Glu/NMDA-induced nitric oxide (NO) production. In the glucose deprivation (GD) study, baicalein but not baicalin showed significant protective effects on the GD-increased LDH release, without affecting the GD-induced NO production, in cultured rat brain neurons. These results suggest that baicalein is the most effective compound among three polyphenols tested in preventing neurotoxicity induced by both glutamate and GD, whereas baicalin was only effective in preventing glutamate toxicity. Wogonin might have a neurotoxic effect on the brain.

Flavonoid wogonin from medicinal herb is neuroprotective by inhibiting inflammatory activation of microglia

Wogonin (5,7-dihydroxy-8-methoxyflavone), a flavonoid originated from the root of a medicinal herb Scutellaria baicalensis Georgi, has been previously shown to have anti-inflammatory activities in various cell types including macrophages. In this work, we have found that wogonin is a potent neuroprotector from natural source. Wogonin inhibited inflammatory activation of cultured brain microglia by diminishing lipopolysaccharide-induced tumor necrosis factor-alpha (TNF-alpha), interleukin-1beta, and nitric oxide (NO) production. Wogonin inhibited NO production by suppressing inducible NO synthase (iNOS) induction and NF-kappaB activation in microglia. Inhibition of inflammatory activation of microglia by wogonin led to the reduction in microglial cytotoxicity toward cocultured PC12 cells, supporting a neuroprotective role for wogonin in vitro. The neuroprotective effect of wogonin was further demonstrated in vivo using two experimental brain injury models; transient global ischemia by four-vessel occlusion and excitotoxic injury by systemic kainate injection. In both animal models, wogonin conferred neuroprotection by attenuating the death of hippocampal neurons, and the neuroprotective effect was associated with inhibition of the inflammatory activation of microglia. Hippocampal induction of inflammatory mediators such as iNOS and TNF-alpha was reduced by wogonin in the global ischemia model, and microglial activation was markedly down-regulated by wogonin in the kainate injection model as judged by microglia-specific isolectin B4 staining. Taken together, our results indicate that wogonin exerts its neuroprotective effect by inhibiting microglial activation, which is a critical component of pathogenic inflammatory responses in neurodegenerative diseases. The current study emphasizes the importance of medicinal herbs and their constituents as an invaluable source for the development of novel neuroprotective drugs.

Quercetin protects the hydrogen peroxide-induced apoptosis via inhibition of mitochondrial dysfuntion in H9c2 cardiomyoblast cells

Quercetin possesses a broad range of pharmacological properties, including protection of LDL from oxidation. However, little is known about the mechanism by which quercetin rescues cardiomyoblasts from oxidative damage. This study was designed to investigate the protective mechanism of quercetin on H(2)O(2)-induced toxicity of H9c2 cardiomyoblasts. Oxidative stress, such as H(2)O(2), ZnCl(2), and menadione, significantly decreased the viability of H9c2 cells, which was accompanied with apparent apoptotic features, including fragmentation of genomic DNA as well as activation of caspase protease. However, quercetin markedly inhibited the apoptotic characteristics via reduction of intracellular reactive oxygen species generation. Also, it prevented the H(2)O(2)-mediated mitochondrial dysfunction, including disruption of mitochondria membrane permeability transition as well as an increase in expression of apoptogenic Bcl-2 proteins, Bcl-2 and Bcl-X(L). Furthermore, pretreatment of quercetin inhibited the activation of caspase-3, thereby both cleavage of poly(ADP-ribose) polymerase and degradation of inhibitor of caspase-activated DNase/DNA fragmentation factor by H(2)O(2) were completely abolished. Taken together, these data suggest that protective effects of quercetin against oxidative injuries of H9c2 cardiomyoblasts may be achieved via modulation of mitochondrial dysfunction and inhibition of caspase activity.

Effect of fraxetin and myricetin on rotenone-induced cytotoxicity in SH-SY5Y cells: comparison with N-acetylcysteine

The purpose of this study was to investigate the potential neuroprotective effects of myricetin (flavonoid) and fraxetin (coumarin) on rotenone-induced apoptosis in SH-SY5Y cells, and the possible signal pathway involved in a neuronal cell model of Parkinson's disease. These two compounds were compared to N-acetylcysteine. The viability of cells was assessed by 3-(4, 5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT), and cytotoxicity was assayed by lactate dehydrogenase (LDH) released into the culture medium. Parameters related to apoptosis, such as caspase-3 activity, the cleavage of poly(ADP-ribose) polymerase and the levels of reactive oxygen species were also determined. Rotenone caused a time- and dose-dependent decrease in cell viability and the degree of LDH release was proportionally to the effects on cell viability. Cells were pretreated with fraxetin, myricetin and N-acetylcysteine at different concentrations for 30 min before exposure to rotenone. Cytotoxicity of rotenone (5 microM) for 16 h was significantly diminished as well as the release of LDH into the medium, by the effect of fraxetin, myricetin and N-acetylcysteine, with fraxetin (100 microM) and N-acetylcysteine (100 microM) being more effective than myricetin (50 microM). Rotenone-induced apoptosis in SH-SY5Y cells was detected by an increase in caspase-3 activity and in the cleavage of poly(ADP-ribose) polymerase. After exposing these cells to rotenone, a significant increase in reactive oxygen species preceded apoptotic events. Fraxetin (100 microM) and N-acetylcysteine (100 microM) not only reduced rotenone-induced reactive oxygen species formation, but also attenuated caspase-3 activity and poly(ADP-ribose) polymerase cleavage at 16 h against rotenone-induced apoptosis. The effect of fraxetin in both experiments was similar to that of N-acetylcysteine. These results demonstrated the protective action of fraxetin and suggest that it can reduce apoptosis, possibly by decreasing free radical generation in SH-SY5Y cells. Myricetin at 100 microM was without any preventive effect.

Differential effects of quercetin, a natural polyphenolic flavonoid, on L-type calcium current in pituitary tumor (GH3) cells and neuronal NG108-15 cells

The effects of quercetin, a natural polyphenolic compound, on voltage-dependent L-type Ca(2+) current (I(Ca,L)) in rat pituitary GH(3) cells were investigated with the aid of the whole-cell voltage-camp technique. Quercetin (0.5-200 microM) stimulated I(Ca,L) in a concentration-dependent manner. The current-voltage (I-V) relationship of I(Ca,L) was slightly shifted to more negative potentials in the presence of quercetin. The EC(50) value of the quercetin-induced stimulation of I(Ca,L) was about 7 microM. The presence of quercetin (5 microM) shifted the steady state inactivation curve of I(Ca,L) to a more negative potential by approximately -10 mV. Although quercetin might increase intracellular cyclic AMP, sp-cAMPS did not affect I(Ca,L). In addition, neither flavone nor wortmannin had any effect on the amplitude of I(Ca,L), while epicatechin and genistein slightly suppressed it. Quercetin (50 microM) decreased the amplitude of tetrodotoxin-sensitive Na(+) current in GH(3) cells. Under current-clamp configuration, quercetin could increase the firing frequency of actions potentials. Conversely, in NG108-15 neuronal cells, quercetin suppressed the amplitude of I(Ca,L). The quercetin-induced inhibition of I(Ca,L) was abolished in NG108-15 cells preincubated with t-butyl hydroperoxide (1 mM). Quercetin-mediated stimulation of I(Ca,L) in GH(3) cells was presumably not associated with the level of intracellular cyclic AMP, or with the activity of tyrosine or phosphoinositide 3-kinases. Therefore, the effects of quercetin on ion currents may, at least in part, contribute to the underlying mechanisms through which it affects neuronal or neuroendocrine function.

Flavonoid baicalein attenuates activation-induced cell death of brain microglia

Baicalein (5,6,7-trihydroxyflavone), a flavonoid originated from the root of Chinese medicinal herb Scutellaria baicalensis, has been shown to exert anti-inflammatory and antioxidant effects, and it is a well known inhibitor of 12-lipoxygenase. We have previously reported that neuroglia undergo nitric oxide (NO)-dependent and NO-independent apoptosis upon inflammatory activation. In the current work, we asked how anti-inflammatory baicalein influences autoregulatory apoptosis of activated microglia and their NO production. Baicalein attenuated NO production and apoptosis of lipopolysaccharide (LPS)-activated, but not interferon-gamma-activated, BV-2 mouse microglial cells as well as rat primary microglia cultures. The inhibition of NO production by baicalein was due to the suppression of inducible NO synthase induction. Moreover, baicalein inhibited LPS-induced nuclear factor-kappaB (NF-kappaB) activity in BV-2 cells without affecting caspase-11 activation, interferon regulatory factor-1 induction, or signal transducer and activator of transcription-1 phosphorylation. Transfection of BV-2 cells with a p65 subunit of NF-kappaB abolished the apoptosis-attenuating effects of baicalein, indicating that the inhibition of NF-kappaB is a major mechanism of action. Baicalein, however, did not significantly affect NO donor-mediated cytotoxicity, and the apoptosis-attenuating effects of baicalein were independent of 12-lipoxygenase inhibition. Based on our previous findings that activation-induced cell death (AICD) of microglia occurs through two separate pathways (NO-dependent pathway and caspase-11-dependent pathway), our current results suggest that baicalein selectively inhibits the NO-dependent apoptotic pathway of activated microglia by suppressing cytotoxic NO production. Also, the AICD-inhibiting effects of baicalein were specific for the inflammatory stimulus that activated microglia.

Hwangryun-Hae-Dok-tang (Huanglian-Jie-Du-Tang) extract and its constituents reduce ischemia-reperfusion brain injury and neutrophil infiltration in rats

The preventive effect of Hwangryun-Hae-Dok-tang (HHDT, Huanglian-Jie-Du-Tang), a Chinese herbal medicine, and its ingredients on ischemia/reperfusion-induced brain injury was evaluated in the rat brain. HHDT consists of four herbs, namely, Coptidis rhizoma, Scutellariae radix, Phellodendri cortex, and Gardeniae fructus. Ischemia was induced by intraluminal occlusion of the right middle cerebral artery for 120 min and reperfusion was continued for 22 h. HHDT (200 mg/kg), Coptidis rhizoma (100 mg/kg), Scutellariae radix (100 mg/kg), Phellodendri cortex (100 mg/kg), and Gardeniae fructus (100 mg/kg) were orally administered, promptly prior to reperfusion and 2 h after reperfusion. Baicalein, a component of Scutellariae radix, was also examined at a dosage of 50 mg/kg given 2 h apart, promptly prior to and 2 h after reperfusion. Total infarction volume in the ipsilateral hemisphere of ischemia/reperfusion rats was significantly lowered by treatment with HHDT, Scutellariae radix, and balicalein. However, the other ingredient of HHDT did not show any ameliorating effects on total infarction volume. The inhibiting effect of Scutellariae radix on total infarction volume was much higher than that of the others. In addition, HHDT, Scutellariae radix, and baicalein significantly inhibited myeloperoxidase (MPO) activity, an index of neutrophil infiltration in ischemic brain tissue at about the same rate (30%). There was marked mismatch between total infarction volume and MPO activity in the Scutellariae radix-treated rats but not in the HHDT- and baicalein-treated groups. Our findings suggest that Scutellariae radix as an ingredient of HHDT plays a crucial protective role in ischemia-induced brain injury. In addition, it is apparent that the effect of Scutellariae radix is the result, in part, of baicalein, a compound contained in Scutellariae radix.

Protective effect of wogonin on endotoxin-induced lethal shock in D-galactosamine-sensitized mice

The effects of wogonin, a major flavonoid from Scutellaria baicalensis Georgi, on lipopolysaccharide (LPS)-induced lethal shock in mice was investigated. Wogonin pretreatment prevented the lethal shock in mice injected with D-galactosamine (D-GalN) and LPS, but not in mice injected with a high dose of LPS. Wogonin definitely inhibited the hepatic injury in mice injected with D-GalN, and LPS and reduced the level of circulating tumor necrosis factor (TNF)-alpha. The reduction was more marked in mice injected with D-GalN and LPS compared with that in mice injected with a high dose of LPS. Wogonin pretreatment did not inhibit the lipid peroxidation in mice receiving either D-GalN and LPS or a high dose of LPS. Wogonin inhibited the in vitro production of TNF-alpha and nitric oxide in LPS-stimulated RAW 264.7 cells. The mechanism of the protective effect of wogonin on the lethal shock in mice injected with D-GalN and LPS is discussed.

In vitro and in vivo inhibitory activities of rutin, wogonin, and quercetin on lipopolysaccharide-induced nitric oxide and prostaglandin E(2) production

Flavonoids are widely distributed in plants, but their biological functions are still unclear. In the present study, in vitro and in vivo experiments were performed to demonstrate the inhibitory activities of rutin, wogonin, and quercetin on lipopolysaccharide-induced nitric oxide (NO) and prostaglandin E(2) production in RAW 264.7 macrophages, primary peritoneal macrophages, and Balb/c mice, respectively. In vitro results showed that wogonin and quercetin dose-dependently suppressed lipopolysaccharide-induced NO production in RAW 264.7 macrophages and primary peritoneal macrophages without a notable cytotoxic effect on either cell types associated with a decrease in inducible nitric oxide synthase (iNOS) protein expression in both cells. Rutin, at 80 microM only, had a slight but obvious inhibitory effect on lipopolysaccharide-induced NO production in primary peritoneal macrophages. Both wogonin and quercetin attenuated lipopolysaccharide-induced prostaglandin E(2) production in vitro. Intravenous injection of lipopolysaccharide (10 mg/kg, i.v.) resulted in a time-dependent induction of NO production in serum, and pretreatment with the L-arginine analog N-nitro-L-arginine methyl ester (L-NAME) blocked this induction. Intravenous pretreatment of Balb/c mice with rutin, wogonin or quercetin for 1 h followed by lipopolysaccharide treatment significantly inhibited lipopolysaccharide-induced NO production, but no inhibition of prostaglandin E(2) production was found. A decrease in iNOS protein, but not cyclooxygenase-2 protein, was detected in liver and lung specimens of lipopolysaccharide-treated Balb/c mice in the presence of rutin, wogonin or quercetin. In conclusion, data obtained both in vitro and in vivo suggest that wogonin and quercetin exert inhibitory activity on lipopolysaccharide-induced NO production through suppression of iNOS expression.