Inhibitory effect of sesaminol glucosides on lipopolysaccharide-induced NF-κB activation and target gene expression in cultured rat astrocytes

The protective role of sesame oil against Parkinson's-like disease induced by manganese in rats

Chronic exposure to manganese (Mn) results in motor dysfunction, biochemical and pathological alterations in the brain. Oxidative stress, inflammation, and dysfunction of dopaminergic and GABAergic systems stimulate activating transcription factor-6 (ATF-6) and protein kinase RNA-like ER kinase (PERK) leading to apoptosis. This study aimed to investigate the protective effect of sesame oil (SO) against Mn-induced neurotoxicity. Rats received 25 mg/kg MnCl2 and were concomitantly treated with 2.5, 5, or 8 ml/kg of SO for 5 weeks. Mn-induced motor dysfunction was indicated by significant decreases in the time taken by rats to fall during the rotarod test and in the number of movements observed during the open field test. Also, Mn resulted in neuronal degeneration as observed by histological staining. The striatal levels of lipid peroxides and reduced glutathione (oxidative stress markers), interleukin-6 and tumor necrosis factor-α (inflammatory markers) were significantly elevated. Mn significantly reduced the levels of dopamine and Bcl-2, while GABA, PERK, ATF-6, Bax, and caspase-3 were increased. Interestingly, all SO doses, especially at 8 ml/kg, significantly improved locomotor activity, biochemical deviations and reduced neuronal degeneration. In conclusion, SO may provide potential therapeutic benefits in enhancing motor performance and promoting neuronal survival in individuals highly exposed to Mn.

Low Density Lipoprotein Receptor-related Protein 2 Expression and Function in Cultured Astrocytes and Microglia

Activation of glial cells, astrocytes and microglia, has been observed in neurodegenerative diseases including Alzheimer's disease (AD). Amyloid β (Aβ), which is aggregated and the aggregation is detected as characteristic pathology in AD brain, is known to be produced by neurons and to activate glial cells. Clearance of Aβ from the brain via active transport system is important to prevent the accumulation and aggregation. Low density lipoprotein receptor-related protein 2 (LRP2/megalin) is an Aβ transporter. However, expression and contribution of LRP2 in astrocytes and microglia remain to be clarified. In the present study, we examined the expression of LRP2 and its roles in cultured astrocytes prepared from rat embryonic brain cortex and mouse microglial cell line BV-2. Both cultured rat astrocytes and BV-2 cells expressed LRP2 mRNA detected by RT-PCR. When lipopolysaccharide (LPS) or all-trans retinoic acid (ATRA) were added to BV-2 cells, LRP2 mRNA expression and uptake of microbeads, Aβ and insulin were increased. On the other hand, LPS decreased LRP2 expression and uptake of Aβ and insulin in cultured astrocytes. Knockdown of LRP2 using siRNA attenuated the LPS- or ATRA-increased uptake of microbeads, Aβ and insulin in BV-2 cells. These results suggest that LRP2 was expressed in both astrocytes and microglia and might be involved in endocytosis activities. Adequate control of LRP2 expression and function in astrocytes and microglia might regulate Aβ and insulin levels in brain and would be a potential target in AD pathology.

Recent status of sesaminol and its glucosides: Synthesis, metabolism, and biological activities

Sesamum indicum is a major and important oilseed crop that is believed to promote human health in many countries, especially in China. Sesame seeds contain two types of lignans: lipid-soluble lignans and water-soluble glucosylated lignans. The major glucosylated lignans are sesaminol glucosides (SGs). So far, four sesaminol isomers and four SGs are identified. During the naturally occurring process of SGs production, sesaminol is generated first from two molecules of E-coniferyl alcohol, and then the sugar is added to the sesaminol one by one, leading to production of SGs. Sesaminol can be prepared from SGs, from sesamolin, and through artificial synthesis. SGs are metabolized in the liver and intestine and are then transported to other tissues. They exhibit several biological activities, most of which are based on their antioxidant and anti-inflammatory activities. In this paper, we present an overview of the current status of research on sesaminol and SGs. We have also discussed their synthesis, preparation, metabolism, and biological activities. It has been suggested that sesaminol and SGs are important biological substances with strong antioxidant properties in vitro and in vivo and are widely used in the food industry, medicine, and cosmetic products. The recovery and utilization of SGs from sesame seed cake after oil processing will generate massive economic benefits.

Activation of Angiotensin-converting Enzyme 2 Protects Against Lipopolysaccharide-induced Glial Activation by Modulating Angiotensin-converting Enzyme 2/Angiotensin (1-7)/Mas Receptor Axis

Neuroinflammation is associated with activation of glial cells and pro-inflammatory arm of the central Renin Angiotensin System (RAS) namely, Angiotensin-Converting Enzyme/Angiotensin II/Angiotensin Type 1 Receptor (ACE/Ang II/AT1R) axis. Apart from this, another axis of RAS also exists, Angiotensin-Converting Enzyme 2/Angiotensin (1-7)/Mas Receptor (ACE2/Ang (1-7)/MasR), which counters ACE/Ang II/AT1R axis by showing anti-inflammatory properties. However, the role of ACE2/Ang (1-7)/MasR axis has not been explored in glial activation and neuroinflammation. Hence, the present study tries to unveil the role of ACE2/Ang (1-7)/MasR axis in lipopolysaccharide (LPS)-induced neuroinflammation using diminazene aceturate (DIZE), an ACE2 activator, in astroglial (C6) and microglial (BV2) cells as well as male SD rats. We found that ACE2 activation efficiently prevented LPS-induced changes by decreasing glial activation, inflammatory signaling, cell migration, ROS generation via upregulation of ACE2/Ang (1-7)/MasR signaling. In addition, activation of ACE2/Ang (1-7)/MasR axis by DIZE significantly suppressed the pro-inflammatory ACE/Ang II/AT1R axis by reducing Ang II level in neuroinflammatory conditions induced by LPS in both in vitro and in vivo. ACE2/Ang (1-7)/MasR axis activation further decreased mitochondrial depolarization and apoptosis, hence providing neuroprotection. Furthermore, to validate that the beneficial effect of the ACE2 activator was indeed through MasR, a selective MasR antagonist (A779) was used that significantly blocked the anti-inflammatory effect of ACE2 activation by DIZE. Hence, our study demonstrated that ACE2 activation imparted neuroprotection by enhancing ACE2/Ang (1-7)/MasR signaling which in turn decreased glial activation, neuroinflammation, and apoptosis and improved mitochondrial health.

Plant Metabolic Network 15: A resource of genome-wide metabolism databases for 126 plants and algae

To understand and engineer plant metabolism, we need a comprehensive and accurate annotation of all metabolic information across plant species. As a step towards this goal, we generated genome-scale metabolic pathway databases of 126 algal and plant genomes, ranging from model organisms to crops to medicinal plants (https://plantcyc.org). Of these, 104 have not been reported before. We systematically evaluated the quality of the databases, which revealed that our semi-automated validation pipeline dramatically improves the quality. We then compared the metabolic content across the 126 organisms using multiple correspondence analysis and found that Brassicaceae, Poaceae, and Chlorophyta appeared as metabolically distinct groups. To demonstrate the utility of this resource, we used recently published sorghum transcriptomics data to discover previously unreported trends of metabolism underlying drought tolerance. We also used single-cell transcriptomics data from the Arabidopsis root to infer cell type-specific metabolic pathways. This work shows the quality and quantity of our resource and demonstrates its wide-ranging utility in integrating metabolism with other areas of plant biology.

Sesame oil mitigates memory impairment, oxidative stress, and neurodegeneration in a rat model of Alzheimer's disease. A pivotal role of NF-κB/p38MAPK/BDNF/PPAR-γ pathways

ETHNOPHARMACOLOGICAL RELEVANCE

Sesame (Sesamum indicum, L., Family: Pedaliaceae) is a notable folk medicine in Middle East, Asia and Africa. Many traditional and pharmacological studies have documented the unique nature of sesame oil (SO). SO has been reported to have many pharmacological effects related to the anti-inflammatory and antioxidant capacity of its components. Neuroinflammation and oxidative stress have been the predominant pathogenic events in Alzheimer's disease (AD) which is one of the most common neurodegenerative diseases.

AIM OF STUDY

we aimed to explore the neuroprotective effect and the probable mechanisms of SO against aluminium chloride (AlCl3)-induced AD symptoms.

MATERIALS AND METHODS

Rats were treated daily with AlCl3 (100 mg/kg/i.p.) either alone or with SO (two different doses) for six weeks. Behavioral (Open-field and Morris water maze tests), histopathological, and biochemical examinations were used to evaluate the neuroprotective effect and the underlying mechanisms of SO against AlCl3-induced AD symptoms.

RESULTS

Our results indicated that SO significantly improved learning and memory impairments induced by AlCl3. Indeed, SO treatment significantly restored the elevated level of acetylcholinesterase (AChE) and amyloid beta (Aβ) overexpression. Moreover, AlCl3 treatment afforded histopathological changes, increase the expression of tumor necrosis factor-alpha (TNF-α) and interleukin-1 beta (IL-1β) in addition to mitigation of oxidative stress status in the brain. SO abolished all these abnormalities. Meanwhile, AlCl3 induced activation of p38 mitogen-activated protein kinase (p38MAPK) and decreased brain-derived neurotrophic factor (BDNF) which were inhibited by SO. Furthermore, SO administration modulated the expression of the peroxisome proliferator-activated receptor gamma (PPAR-γ) and nuclear factor kappa B (NF-κB).

CONCLUSIONS

In conclusion, the neuroprotective effect of SO involved the modulation of different mechanisms targeting oxidative stress, neuroinflammation, and cognitive functions. SO may modulate different molecular targets involved in AD pathogenesis by alterations of NF-κB/p38MAPK/BDNF/PPAR-γ signalling and this may be attributed to the synergistic effect of their active components.

Anti-Inflammatory and Anticancer Properties of Bioactive Compounds from Sesamum indicum L.-A Review

The use of foodstuff as natural medicines has already been established through studies demonstrating the pharmacological activities that they exhibit. Knowing the nutritional and pharmacological significance of foods enables the understanding of their role against several diseases. Among the foods that can potentially be considered as medicine, is sesame or Sesamum indicum L., which is part of the Pedaliaceae family and is composed of its lignans such as sesamin, sesamol, sesaminol and sesamolin. Its lignans have been widely studied and are known to possess antiaging, anticancer, antidiabetes, anti-inflammatory and antioxidant properties. Modern chronic diseases, which can transform into clinical diseases, are potential targets of these lignans. The prime example of chronic diseases is rheumatic inflammatory diseases, which affect the support structures and the organs of the body and can also develop into malignancies. In line with this, studies emphasizing the anti-inflammatory and anticancer activities of sesame have been discussed in this review.

S-Equol, a Major Isoflavone from Soybean, Inhibits Nitric Oxide Production in Lipopolysaccharide-Stimulated Rat Astrocytes Partially via the GPR30-Mediated Pathway

Cumulative evidence indicates that estrogen receptor (ER) agonists attenuate neuroinflammation. Equol, a major isoflavone from soybean, exhibits estrogen-like biological activity, but their effect on inflammatory response has not been well established. Here, we investigated the effect of S-equol on nitric oxide (NO) production, well-known inflammatory change in astrocytes stimulated by LPS. S-Equol attenuated LPS-induced NO production with a concomitant decrease in expression of inducible NO synthase (iNOS). S-Equol did not affect LPS-induced increase in intracellular ROS production. Intracellular ER blocker ICI 182.780 had no effect on S-equol-induced decrease in NO production. Addition of G-15, antagonist of G protein-coupled receptor 30 which is nongenomic ER and located on cell surface, partially recovered S-equol-induced attenuation of NO production. These findings suggest that attenuation of NO production by S-equol may mitigate LPS-induced neuroinflammation in astrocytes. S-Equol may exert a glioprotective effect, at least in part, via a nongenomic effect.

Acetate Attenuates Lipopolysaccharide-Induced Nitric Oxide Production Through an Anti-Oxidative Mechanism in Cultured Primary Rat Astrocytes

The biomolecule acetate can be utilized for energy production, lipid synthesis, and several metabolic processes. Acetate supplementation reduces neuroglial activation in a model of neuroinflammation induced by intraventricular injection of lipopolysaccharide (LPS). To investigate the mechanisms underlying the anti-inflammatory effect of acetate on glial cells, we examined the effect of acetate on nitric oxide (NO) production, which was experimentally activated by LPS, in cultured primary rat astrocytes. Acetate attenuated the LPS-induced NO production in a dose-dependent manner, although cell viability was not affected. Acetate suppressed the phosphorylation of p38-mitogen-activated protein kinase 24 h after LPS treatment. Acetate decreased the LPS-induced production of intracellular reactive oxygen species (ROS) at 4-24 h concomitant with an increase in glutathione. Acetate rescued astrocytes from the hydrogen peroxide-induced cell death by reducing ROS levels. These findings suggest that attenuation of NO production by acetate may alleviate glial cell damage during neuroinflammation. Acetate may offer a glioprotective effect through an anti-oxidative mechanism.

Tricin, flavonoid from Njavara reduces inflammatory responses in hPBMCs by modulating the p38MAPK and PI3K/Akt pathways and prevents inflammation associated endothelial dysfunction in HUVECs

Previous studies revealed the potent anti-inflammatory activity of tricin, the active component of Njavara rice bran. Here, we report the involvement of specific signaling pathways in the protective effect of tricin against LPS induced inflammation in hPBMCs and the role of tricin in modulating endothelial dysfunction in LPS induced HUVECs. Pretreatment with tricin (15μM) significantly inhibited the release of TNF-α and was comparable to the specific pathway blockers like ERK inhibitor (PD98059), JNK inhibitor (SP600125) and p38 inhibitor (SB203580), whereas an increased release of TNF-α was observed in PI3K/Akt inhibitor (LY294002) treated cells. Tricin alone and combination treatment of tricin and SB203580 showed more significant inhibition of activation of COX-2 and TNF-α than that of SB203580 alone treated group. Combination treatment of tricin and LY294002 showed increased activation of COX-2 and TNF-α, proved that PI3K activation is essential for the anti-inflammatory effect of tricin. Studies conducted on HUVECs revealed the protective effect of tricin against endothelial dysfunction associated with LPS induced inflammation by inhibiting the activation of proinflammatory mediators like TNF-α, IFN-γ, MCP 1 by modulating NF-κB and MAPK signaling pathways. ELISA and flow cytometric analysis again confirmed the protection of tricin against endothelial damage, especially from the decreased activation of cell adhesion molecules like ICAM-1, VCAM-1 and E-Selectin upon tricin treatment. This work establishes the mechanism behind the potent anti-inflammatory activity of the flavonoid tricin.

Propofol Inhibits Lipopolysaccharide-Induced Inflammatory Responses in Spinal Astrocytes via the Toll-Like Receptor 4/MyD88-Dependent Nuclear Factor-κB, Extracellular Signal-Regulated Protein Kinases1/2, and p38 Mitogen-Activated Protein Kinase Pathways

BACKGROUND

In this study, we investigated the effect of propofol, a commonly used IV anesthetic, on lipopolysaccharide (LPS)-induced inflammatory responses in astrocytes and explored the molecular mechanisms by which it occurs.

METHODS

Astrocytes were stimulated with LPS (1.0 μg/mL) in the absence and presence of different concentrations of propofol. The expression of astrocyte marker glial fibrillary acidic protein (GFAP) in astrocytes was detected using immunofluorescence staining and Western blot analysis. The levels of interleukin (IL)-1β, IL-6, and tumor necrosis factor-α were measured using an enzyme-linked immunosorbent assay. The mRNA level of Toll-like receptor 4 (TLR4) was determined by semiquantitative reverse transcriptase-polymerase chain reaction. The protein expressions of TLR4, myeloid differentiation factor 88 (MyD88), p- extracellular signal-regulated protein kinases (ERK)1/2, p-c-Jun N-terminal kinase, p-p38 mitogen-activated protein kinase (MAPK), p-I-κBα, I-κBα, and p-nuclear factor-κB (NF-κB)p65 were detected by Western blot.

RESULTS

Our results show that after stimulation with LPS, the levels of IL-1β, IL-6, and tumor necrosis factor-α and the expression of GFAP in astrocytes were up-regulated significantly. In addition, the expression of TLR4, MyD88, p-ERK1/2, p-c-Jun N-terminal kinase, p-p38 MAPK, and p-NF-κBp65 increased, whereas the expression of total I-κBα decreased upon stimulation with LPS. Propofol (10 μM) reduced the secretion of proinflammatory cytokines, inhibited the expressions of GFAP, TLR4, MyD88, p-ERK1/2, p-p38 MAPK, and p-NF-κBp65 in astrocytes challenged with LPS.

CONCLUSIONS

In the present study, propofol 10 μM but not lower clinically relevant or higher supra-clinical concentrations attenuated LPS-induced astrocyte activation and subsequent inflammatory responses by inhibiting the TLR4/MyD88-dependent NF-κB, ERK1/2, and p38 MAPK pathways.

Bee venom ameliorates lipopolysaccharide-induced memory loss by preventing NF-kappaB pathway

Background

Accumulation of beta-amyloid and neuroinflammation trigger Alzheimer’s disease. We previously found that lipopolysaccharide (LPS) caused neuroinflammation with concomitant accumulation of beta-amyloid peptides leading to memory loss. A variety of anti-inflammatory compounds inhibiting nuclear factor kappaB (NF-κB) activation have showed efficacy to hinder neuroinflammation and amyloidogenesis. We also found that bee venom (BV) inhibits NF-κB.

Methods

A mouse model of LPS-induced memory loss used administration of BV (0.8 and 1.6 μg/kg/day, i.p.) to ICR mice for 7 days before injection of LPS (2.5 mg/kg/day, i.p.). Memory loss was assessed using a Morris water maze test and passive avoidance test. For in vitro study, we treated BV (0.5, 1, and 2 μg/mL) to astrocytes and microglial BV-2 cells with LPS (1 μg/mL).

Results

We found that BV inhibited LPS-induced memory loss determined by behavioral tests as well as cell death. BV also inhibited LPS-induced increases in the level of beta-amyloid (Aβ), β-and γ-secretases activities, NF-κB and its DNA-binding activity and expression of APP, and BACE1 and neuroinflammation proteins (COX-2, iNOS, GFAP and IBA-1) in the brain and cultured cells. In addition, pull-down assay and molecular modeling showed that BV binds to NF-κB.

Conclusions

BV attenuates LPS-induced amyloidogenesis, neuroinflammation, and therefore memory loss via inhibiting NF-κB signaling pathway. Thus, BV could be useful for treatment of Alzheimer’s disease.

Mechanism of anti-inflammatory effect of tricin, a flavonoid isolated from Njavara rice bran in LPS induced hPBMCs and carrageenan induced rats

Njavara is an indigenous medicinal rice variety traditionally used in Ayurvedic system of medicine practiced in Kerala, India. Tricin is a bioflavonoid present in significantly higher levels in rice bran of Njavara. Present study attempted to identify the molecular target of tricin in TLR mediated signaling pathways by using lipopolysaccharide (LPS) induced human peripheral blood mononuclear cells (hPBMCs) and carrageenan induced paw edema in rats as experimental models. Tricin acted upstream in the activation of inflammation cascade by interfering with TLR4 activation, preferably by blocking the LPS induced activation of TLR4, MYD88 and TRIF proteins in hPBMCs. Subsequently, tricin significantly blocked the activation of downstream kinases like p38MAPK, JNK1/2 and IRF3. Thus the inhibitory effect of tricin on NF-κB and IRF3 together confirms the specific inhibition of both MYD88 dependent and TRIF dependent pathways. Tricin treatment also inhibited the pro-inflammatory effect of LPS by blocking the TLR4 signaling mediated activation of cytosolic phospholipase A2 (cPLA2), which is confirmed by specific inhibition of COX-2. Results demonstrated that in addition to NF-κB, tricin can prevent the activation of STAT proteins by significantly inhibiting the activation of both STAT1 and STAT3 via the down regulation of upstream phosphorylating enzymes like JAK1 and JAK2. The protective anti-inflammatory effect of tricin was also confirmed by in vivo experiments. Thus, this study provides strong evidence that tricin exerts its anti-inflammatory effect via a mechanism involving the TLR4/NF-κB/STAT signaling cascade.

Effect of sesame lignans on TNF-alpha-induced expression of adhesion molecules in endothelial cells

The expression of cell adhesion molecules (CAMs) has been implicated as one of the most important causes of the development of inflammatory diseases such as atherosclerosis, and, it is speculated that the prevention of it is an effective approach to the control of atherosclerosis. In the present study, we investigated the effect of sesame lignans on the expression of CAMs in human umbilical vein endothelial cells (HUVECs) induced by tumor necrosis factor-alpha (TNF-alpha). Based on cell-ELISA analysis, we found that sesaminol-6-catechol downregulated the TNF-alpha-induced expression of CAMs in a dose-dependent manner. Moreover, these inhibitory effects were caused to be drastically exerted by downregulating the CAM proteins in TNF-alpha-activated HUVECs at transcriptional level. This suggests, that sesaminol-6-catehcol suppresses the expression of CAMs, and may be an active component of sesame lignans.

Tissue distribution and elimination of estrogenic and anti-inflammatory catechol metabolites from sesaminol triglucoside in rats

Sesaminol triglucoside (STG) is the main sesame (Sesamum indicum L.) lignan. Like many other plant lignans, STG can be converted to the mammalian lignans by intestinal microbiota. The objectives of the present study were to investigate the distribution of STG metabolite in rats, and the effects of STG and its metabolite on in vitro inflammation and estrogenic activities. STG was metabolized via intestinal microflora to a biologically active catechol moiety which would then be absorbed into the body in rats. After oral administration of STG to Sprague-Dawley rats, the concentrations of major STG metabolites in rectum, cecum, colon, and small intestines are higher than those in liver, lung, kidney, and heart. Its concentration in brain is low but detectable. The present study demonstrates that STG may be metabolized to form the catechol metabolites first by intestinal microflora and then incorporated via intestine absorption into the cardiovascular system and transported to other tissues. Results showed that the catechol metabolites were found to be able to penetrate the tail end of intestines (large intestine) and go through urinary excretion. STG metabolites significantly reduced the production of IL-6 and TNF-alpha in RAW264.7 murine macrophages stimulated with lipopolysaccharide. The estrogenic activities of STG metabolites were also established by ligand-dependent transcriptional activation through estrogen receptors. This study clearly shows that STG has anti-inflammatory and estrogenic activities via metabolism of intestinal microflora.

Sesaminol glucosides protect beta-amyloid peptide-induced cognitive deficits in mice

This study was designed to investigate the effect of sesaminol glycosides (SG), one of the most abundant lignan glycosides in sesame (Sesamum indicum LINN.) seed, on cognitive deficits and oxidative stress induced by intracerebroventricular (i.c.v.) injection of beta-amyloid protein (Abeta)(25-35) in mice. Mice were fed diets containing 0%, 0.25%, or 0.5% of SG for six weeks. Dietary SG showed a protective effect against Abeta-induced learning and memory deficits in passive avoidance and the Morris water maze test. Abeta caused significant neuronal loss in the CA1 and CA3 regions of the hippocampus, but SG supplement showed decrease of the Abeta(25-35) induced neuronal loss. The SG supplementation significantly decreased thiobarbituric acid reactive substance values and 8-hydroxy-2'-deoxyguanosine (8-OHdG) levels in brain tissue. SG also reversed the activity of glutathione peroxidase (GPx), which is decreased by Abeta. These results suggest that SG protects against cognitive deficits induced by Abeta(25-35), in part through its antioxidant activity.

Differential tissue distribution of sesaminol triglucoside and its metabolites in rats fed with lignan glycosides from sesame meal with or without nano/submicrosizing

Lignan glycosides are important functional compounds in sesame meal. In the present study, we investigated whether the tissue distribution of nano/submicrosized lignan glycosides from sesame meal (N-LGSM) differs from lignan glycosides from sesame meal (LGSM). LGSM was nano/submicrosized with 0.3 mm zirconia beads as the milling media. The average particle size of the 4% LGSM aqueous suspension reduced rapidly from approximately 2 microm to 200 nm after media milling at an agitation speed of 3600 rpm for 30 min. We examined the tissue distribution of sesaminol triglucoside (ST), the main component in LGSM, in Sprague-Dawley (SD) rats. The concentrations of ST were determined in various tissues and plasma within a 24 h period after oral administration of N-LGSM and LGSM (800 mg/kg of body weight). The results showed that higher concentrations of ST and its metabolites (sesaminol, sesaminol sulfate, and sesaminol glucuronide) were found in N-LGSM compared to those in LGSM in most tissues, especially liver and small intestine. Sesaminol glucuronide was the main metabolite in rats. After 3 h of oral administration, around 70% higher concentration of sesaminol glucuronide was found in N-LGSM compared to that in LGSM. This study clearly showed that LGSM is more bioavailable after nano/submicrosizing.

JNK pathway is involved in the inhibition of inflammatory target gene expression and NF-kappaB activation by melittin

Background

Bee venom therapy has been used to treat inflammatory diseases including rheumatoid arthritis in humans and in experimental animals. We previously found that bee venom and melittin (a major component of bee venom) have anti-inflammatory effect by reacting with the sulfhydryl group of p50 of nuclear factor-kappa B (NF-κB) and IκB kinases (IKKs). Since mitogen activated protein (MAP) kinase family is implicated in the NF-κB activation and inflammatory reaction, we further investigated whether activation of MAP kinase may be also involved in the anti-inflammatory effect of melittin and bee venom.

Methods

The anti-inflammatory effects of melittin and bee venom were investigated in cultured Raw 264.7 cells, THP-1 human monocytic cells and Synoviocytes. The activation of NF-κB was investigated by electrophoretic mobility shift assay. Nitric oxide (NO) and prostaglandin E₂ (PGE₂) were determined either by Enzyme Linked Immuno Sorbent Assay or by biochemical assay. Expression of IκB, p50, p65, inducible nitric oxide synthetase (iNOS), cyclooxygenase-2 (COX-2) as well as phosphorylation of MAP kinase family was determined by Western blot.

Results

Melittin (0.5–5 μg/ml) and bee venom (5 and 10 μg/ml) inhibited lipopolysaccharide (LPS, 1 μg/ml) and sodium nitroprusside (SNP, 200 μM)-induced activation of c-Jun NH2-terminal kinase (JNK) in RAW 264.7 cells in a dose dependent manner. However, JNK inhibitor, anthra [1,9-cd]pyrazole-6 (2H)-one (SP600215, 10–50 μM) dose dependently suppressed the inhibitory effects of melittin and bee venom on NF-κB dependent luciferase and DNA binding activity via suppression of the inhibitory effect of melittin and bee venom on the LPS and SNP-induced translocation of p65 and p50 into nucleus as well as cytosolic release of IκB. Moreover, JNK inhibitor suppressed the inhibitory effects of melittin and bee venom on iNOS and COX-2 expression, and on NO and PGE₂ generation.

Conclusion

These data show that melittin and bee venom prevent LPS and SNP-induced NO and PGE₂ production via JNK pathway dependent inactivation of NF-κB, and suggest that inactivation of JNK pathways may also contribute to the anti-inflammatory and anti-arthritis effects of melittin and bee venom.

Sequential glucosylation of a furofuran lignan, (+)-sesaminol, by Sesamum indicum UGT71A9 and UGT94D1 glucosyltransferases

(+)-Sesaminol 2-O-triglucoside is the most abundant water-soluble furofuran lignan in sesame seeds (Sesamum indicum) and is considered to be a beneficial compound for human health. The biosyntheses and physiological roles of lignan glycosides, however, remain elusive. Here we report the molecular identification and biochemical characterization of two Sesamum uridine diphosphate (UDP) glucose:lignan glucosyltransferases. Sesamum indicum UGT71A9 preferentially glucosylated at the 2-hydroxyl group of (+)-sesaminol, resulting in (+)-sesaminol 2-O-glucoside. Similarly, two UGT71A9 homologs from Sesamum radiatum (UGT71A10) and Sesamum alatum (UGT71A8) also showed (+)-sesaminol glucosylating activity, evidencing the functional conservation of (+)-sesaminol 2-O-glucosyltransferases in the Sesamum genus. In addition, S. indicum UGT94D1 specifically glucosylated at the 6'-hydroxyl group of the sugar moiety of (+)-sesaminol 2-O-glucoside but not at that of flavonoid glucosides. The gene expression patterns of UGT71A9 and UGT94D1 during seed development were correlated with the glucosylating activities toward (+)-sesaminol in planta, suggesting that the two lignan UDP-glycosyltransferases participate in the sequential glucosylation steps in the biosynthesis of (+)-sesaminol 2-O-triglucoside.

Inhibitory effect of obovatol on nitric oxide production and activation of NF-κB/MAP kinases in lipopolysaccharide-treated RAW 264.7cells

The components of Magnolia obovata are known to have many pharmacological activities. In this study, we investigated the effects of obovatol, a neolignan compound isolated from the leaves of M. obovata, on nitric oxide (NO) production and NF-kappaB activity in lipopolysaccharide (LPS)-activated RAW 264.7 cells. The results show that obovatol (1-5 microM) significantly inhibited LPS-induced NO production in a concentration-dependent manner (IC(50): 0.91 microM). Consistent with the inhibitory effect on NO production, obovatol inhibits the expression of inducible nitric oxide synthase and cyclooxygenase-2 expression. Furthermore, obovatol suppressed NF-kappaB (p50 and p65) translocation to the nucleus as well as IkappaB release resulting in the inhibition of the DNA binding activity of the NF-kappaB. Obovatol also inhibited c-Jun N-terminal kinase (JNK) and extracellular signal-regulated kinase (ERK) signal, which are the most significantly involved signal in NO production and NF-kappaB activation. When the cells were treated with the combination of obovatol with U0126 (an ERK inhibitor) or SP600125 (a JNK inhibitor) as well as with SC-514 (an IKK2 inhibitor), much more inhibition of NO production was observed than that by obovatol alone. The present results suggest that obovatol has an inhibitory effect on NO production through the inhibition of NF-kappaB/MAPK activity, and thus can be used as an anti-inflammatory agent.

Caffeic acid attenuates neuronal damage, astrogliosis and glial scar formation in mouse brain with cryoinjury

Traumatic brain injury induces neuron damage in early phase, and astrogliosis and the formation of the glial scar in late phase. Caffeic acid (3, 4-dihydroxycinnamic acid), one of the natural phenolic compounds, exerts neuroprotective effects against ischemic brain injuries with anti-oxidant and anti-inflammatory properties, and by scavenging reactive species. However, whether caffeic acid has protective effects against traumatic brain injury is unknown. Therefore, we determined the effect of caffeic acid on the lesion in the early (1 day) and late phases (7 to 28 days) of cryoinjury in mice. We found that caffeic acid (10 and 50 mg/kg, i.p., for 7 days after cryoinjury) reduced the lesion area and attenuated the neuron loss around the lesion core 1 to 28 days, but attenuated the neuron loss in the lesion core only 1 day after cryoinjury. Moreover, caffeic acid attenuated astrocyte proliferation, glial scar wall formation and glial fibrillary acidic protein (GFAP) protein expression in the late phase of cryoinjury (7 to 28 days). Caffeic acid also inhibited the reduction of superoxide dismutase activity and the increase in malondialdehyde content in the brain 1 day after cryoinjury. These results indicate that caffeic acid exerts a protective effect in traumatic brain injury, especially on glial scar formation in the late phase, which at least is associated with its anti-oxidant ability.