Protective effect of Rhei Rhizoma on reflux esophagitis in rats via Nrf2-mediated inhibition of NF-κB signaling pathway

Background

Rhei Rhizoma has been widely used as a traditional herbal medicine to treat various inflammatory diseases. The present study was conducted to evaluate its anti-inflammatory activity against experimental reflux-induced esophagitis (RE) in SD rats.

Methods

Rhei Rhizoma was administered at 125 or 250 mg/kg body weight per day for 7 days prior to the induction of reflux esophagitis, and its effect was compared with RE control and normal rats.

Results

Rhei Rhizoma administration markedly ameliorated mucosal damage on histological evaluation. The elevated reactive oxygen species in the esophageal tissue of RE control rats decreased with the administration of Rhei Rhizoma. RE control rats exhibited the down-regulation of antioxidant-related proteins, such as nuclear factor-erythroid 2-related factor 2 (Nrf2) and heme oxygenase-1 (HO-1) expression levels, in the presence of esophagitis; however, the levels with Rhei Rhizoma treatment were significantly higher than those in RE control rats. Moreover, RE control rats exhibited the up-regulation of protein expressions related to oxidative stress in the presence of esophagitis, but Rhei Rhizoma administration significantly reduced the expression of inflammatory proteins through mitogen-activated protein kinase (MAPK)-related signaling pathways. The protein expressions of inflammatory mediators and cytokines by nuclear factor-kappa B (NF-κB) activation were modulated through blocking the phosphorylation of inhibitor of nuclear factor kappa B (IκB)α.

Conclusion

Our findings support the therapeutic evidence for Rhei Rhizoma ameliorating the development of esophagitis via regulating inflammation through the activation of the antioxidant pathway.

Electronic supplementary material

The online version of this article (doi:10.1186/s12906-015-0974-z) contains supplementary material, which is available to authorized users.

The effects of red ginseng saponin fraction-A (RGSF-A) on phagocytosis and intracellular signaling in Brucella abortus infected RAW 264.7 cells

This study indicated that RGSF-A caused a marked reduction in the adherence, internalization and intracellular growth of Brucella abortus in RGSF-A-treated cells. Furthermore, a decline in the intensity of F-actin fluorescence was observed in RGSF-A-treated cells compared with untreated B. abortus-infected cells. In addition, an evaluation of phagocytic signaling proteins by Western blot analysis revealed an apparent reduction of ERK and p38α phosphorylation levels in B. abortus-infected RGSF-A-treated cells compared with the control. Upon intracellular trafficking of the pathogen, a higher number of B. abortus-containing phagosomes colocalized with LAMP-1 in RGSF-A-treated cells compared with control cells. These results strongly suggest that inhibition of B. abortus uptake could be mediated by suppression in the activation of MAPKs signaling proteins phospho-ERK 1/2, and p38 levels. On the other hand, inhibition of intracellular replication results from the enhancement of phagolysosome fusion in host macrophages. This study highlights the phagocytic and intracellular modulating effect of RGSF-A and its potential as an alternative remedy to control B. abortus infection.

Acetyl Eburicoic Acid from Laetiporus sulphureus var. miniatus Suppresses Inflammation in Murine Macrophage RAW 264.7 Cells

The basidiomycete Laetiporus sulphureus var. miniatus belongs to the Aphyllophorales, Polyporaceae, and grows on the needleleaf tree. The fruiting bodies of Laetiporus species are known to produce N-methylated tyramine derivatives, polysaccharides, and various lanostane triterpenoids. As part of our ongoing effort to discover biologically active compounds from wood-rotting fungi, an anti-inflammatory triterpene, LSM-H7, has been isolated from the fruiting body of L. sulphureus var. miniatus and identified as acetyl eburicoic acid. LSM-H7 dose-dependently inhibited the NO production in RAW 264.7 cells without any cytotoxicity at the tested concentrations. Furthermore it suppressed the production of proinflammatory cytokines, mainly inducible nitric oxide synthase, cyclooxygenase-2, interleukin (IL)-1β, IL-6 and tumor necrosis factor α, when compared with glyceraldehyde 3-phosphate dehydrogenase. These data suggest that LSM-H7 is a crucial component for the anti-inflammatory activity of L. sulphureus var. miniatus.

Total saponin from Korean Red Ginseng inhibits binding of adhesive proteins to glycoprotein IIb/IIIa via phosphorylation of VASP (Ser(157)) and dephosphorylation of PI3K and Akt

Background

Binding of adhesive proteins (i.e., fibrinogen, fibronectin, vitronectin) to platelet integrin glycoprotein IIb/IIIa (αIIb/β₃) by various agonists (thrombin, collagen, adenosine diphosphate) involve in strength of thrombus. This study was carried out to evaluate the antiplatelet effect of total saponin from Korean Red Ginseng (KRG-TS) by investigating whether KRG-TS inhibits thrombin-induced binding of fibrinogen and fibronectin to αIIb/β₃.

Methods

We investigated the effect of KRG-TS on phosphorylation of vasodilator-stimulated phosphoprotein (VASP) and dephosphorylation of phosphatidylinositol 3-kinase (PI3K) and Akt, affecting binding of fibrinogen and fibronectin to αIIb/β₃, and clot retraction.

Results

KRG-TS had an antiplatelet effect by inhibiting the binding of fibrinogen and fibronectin to αIIb/β₃ via phosphorylation of VASP (Ser¹⁵⁷), and dephosphorylation of PI3K and Akt on thrombin-induced platelet aggregation. Moreover, A-kinase inhibitor Rp-8-Br-cyclic adenosine monophosphates (cAMPs) reduced KRG-TS-increased VASP (Ser¹⁵⁷) phosphorylation, and increased KRG-TS-inhibited fibrinogen-, and fibronectin-binding to αIIb/β₃. These findings indicate that KRG-TS interferes with the binding of fibrinogen and fibronectin to αIIb/β₃ via cAMP-dependent phosphorylation of VASP (Ser¹⁵⁷). In addition, KRG-TS decreased the rate of clot retraction, reflecting inhibition of αIIb/β₃ activation. In this study, we clarified ginsenoside Ro (G-Ro) in KRG-TS inhibited thrombin-induced platelet aggregation via both inhibition of [Ca²⁺]_i mobilization and increase of cAMP production.

Conclusion

These results strongly indicate that KRG-TS is a beneficial herbal substance inhibiting fibrinogen-, and fibronectin-binding to αIIb/β₃, and clot retraction, and may prevent platelet αIIb/β₃-mediated thrombotic disease. In addition, we demonstrate that G-Ro is a novel compound with antiplatelet characteristics of KRG-TS.

Inhibitory effects of total saponin from Korean Red Ginseng on [Ca(2+)]i mobilization through phosphorylation of cyclic adenosine monophosphate-dependent protein kinase catalytic subunit and inositol 1,4,5-trisphosphate receptor type I in human platelets

Background

Intracellular Ca²⁺([Ca²⁺]_i) is a platelet aggregation-inducing molecule. Therefore, understanding the inhibitory mechanism of [Ca²⁺]_i mobilization is very important to evaluate the antiplatelet effect of a substance. This study was carried out to understand the Ca²⁺-antagonistic effect of total saponin from Korean Red Ginseng (KRG-TS).

Methods

We investigated the Ca²⁺-antagonistic effect of KRG-TS on cyclic nucleotides-associated phosphorylation of inositol 1,4,5-trisphosphate receptor type I (IP₃RI) and cyclic adenosine monophosphate (cAMP)-dependent protein kinase (PKA) in thrombin (0.05 U/mL)-stimulated human platelet aggregation.

Results

The inhibition of [Ca²⁺]_i mobilization by KRG-TS was increased by a PKA inhibitor (Rp-8-Br-cAMPS), which was more stronger than the inhibition by a cyclic guanosine monophosphate (cGMP)-dependent protein kinase (PKG) inhibitor (Rp-8-Br-cGMPS). In addition, Rp-8-Br-cAMPS inhibited phosphorylation of PKA catalytic subunit (PKAc) (Thr¹⁹⁷) by KRG-TS. The phosphorylation of IP₃RI (Ser¹⁷⁵⁶) by KRG-TS was very strongly inhibited by Rp-8-Br-cAMPS compared with that by Rp-8-Br-cGMPS. These results suggest that the inhibitory effect of [Ca²⁺]_i mobilization by KRG-TS is more strongly dependent on a cAMP/PKA pathway than a cGMP/PKG pathway. KRG-TS also inhibited the release of adenosine triphosphate and serotonin. In addition, only G-Rg3 of protopanaxadiol in KRG-TS inhibited thrombin-induced platelet aggregation.

Conclusion

These results strongly indicate that KRG-TS is a potent beneficial compound that inhibits [Ca²⁺]_i mobilization in thrombin–platelet interactions, which may result in the prevention of platelet aggregation-mediated thrombotic disease.

The inhibitory mechanism of crude saponin fraction from Korean Red Ginseng in collagen-induced platelet aggregation

Background

Korean Red Ginseng has been used as a traditional oriental medicine to treat illness and to promote health for several thousand years in Eastern Asia. It is widely accepted that ginseng saponins, ginsenosides, are the major active ingredients responsible for Korean Red Ginseng’s therapeutic activity against many kinds of illness. Although the crude saponin fraction (CSF) displayed antiplatelet activity, the molecular mechanism of its action remains to be elucidated.

Methods

The platelet aggregation was induced by collagen, the ligand of integrin α_IIβ_I and glycoprotein VI. The crude saponin’s effects on granule secretion [e.g., calcium ion mobilization and adenosine triphosphate (ATP) release] were determined. The activation of mitogen-activated protein kinases (MAPKs), including extracellular signal-regulated protein kinase 1/2 (ERK1/2), c-Jun N-terminal kinases (JNKs), and p38 MAPK, and phosphoinositide 3-kinase (PI3K)/Akt was analyzed by immunoblotting. In addition, the activation of integrin α_IIbβ_III was examined by fluorocytometry.

Results

CSF strongly inhibited collagen-induced platelet aggregation and ATP release in a concentration-dependent manner. It also markedly suppressed [Ca²⁺]_i mobilization in collagen-stimulated platelets. Immunoblotting assay revealed that CSF significantly suppressed ERK1/2, p38, JNK, PI3K, Akt, and mitogen-activated protein kinase kinase 1/2 phosphorylation. In addition, our fraction strongly inhibited the fibrinogen binding to integrin α_IIbβ₃.

Conclusion

Our present data suggest that CSF may have a strong antiplatelet property and it can be considered as a candidate with therapeutic potential for the treatment of cardiovascular disorders involving abnormal platelet function.

Baicalein inhibits agonist- and tumor cell-induced platelet aggregation while suppressing pulmonary tumor metastasis via cAMP-mediated VASP phosphorylation along with impaired MAPKs and PI3K-Akt activation

Recently, the importance of platelet activation in cancer metastasis has become generally accepted. As a result, the development of new platelet inhibitors with minimal adverse effects is now a promising area of targeted cancer therapy. Baicalein is a functional ingredient derived from the root of Scutellaria baicalensis Georgi, a plant used intraditional medicine. The pharmacological effects of this compound including anti-oxidative and anti-inflammatory activities have already been demonstrated. However, its effects on platelet activation are unknown. We therefore investigated the effects of baicalein on ligand-induced platelet aggregation and pulmonary cancer metastasis. In the present study, baicalein inhibited agonist-induced platelet aggregation, granule secretion markers (P-selectin expression and ATP release), [Ca(2+)]i mobilization, and integrin αIIbβ3 expression. Additionally, baicalein attenuated ERK2, p38, and Akt activation, and enhanced VASP phosphorylation. Indeed, baicalein was shown to directly inhibit PI3K kinase activity. Moreover, baicalein attenuated the platelet aggregation induced by C6 rat glioma tumor cells in vitro and suppressed CT26 colon cancer metastasis in mice. These features indicate that baicalein is a potential therapeutic drug for the prevention of cancer metastasis.

Hemeoxygenase 1 partly mediates the anti-inflammatory effect of dieckol in lipopolysaccharide stimulated murine macrophages

Eisenia bicyclis is edible brown algae recognized as a rich source of bioactive derivatives mainly phlorotannins reported for their anti-oxidant properties. Of all phlorotannins identified so far, dieckol has shown the most potent effect in anti-inflammatory, radical scavenging and neuroprotective functions. However, whether dieckol up-regulates hemeoxygenase 1 (HO-1) and this mediates its anti-inflammatory effect in murine macrophages remains poorly understood. Dieckol (12.5-50 μM) inhibited nitric oxide production and attenuated inducible nitric oxide synthase, phospho (p)-PI-3K, p-Akt, p-IKK-α/β, p-IκB-α and nuclear p-NF-κBp65 protein expressions, and NF-κB transcriptional activity in LPS (0.1 μg/ml) stimulated murine macrophages. On the other hand, dieckol up-regulated HO-1 which partly mediated its anti-inflammatory effect in murine macrophages. Thus, dieckol appeared to be a potential therapeutic agent against inflammation through HO-1 up-regulation.

Regulator of G protein signaling 2 (RGS2) deficiency accelerates the progression of kidney fibrosis

The regulator of G protein signaling 2 (RGS2) is a potent negative regulator of Gq protein signals including the angiotensin II (AngII)/AngII receptor signal, which plays a critical role in the progression of fibrosis. However, the role of RGS2 on the progression of kidney fibrosis has not been assessed. Here, we investigated the role of RGS2 in kidney fibrosis induced by unilateral ureteral obstruction (UUO) in mice. UUO resulted in increased expression of RGS2 mRNA and protein in the kidney along with increases of AngII and its type 1 receptor (AT1R) signaling and fibrosis. Furthermore, UUO increased the levels of F4/80, Ly6G, myeloperoxidase, and CXCR4 in the kidneys. RGS2 deficiency significantly enhanced these changes in the kidney. RGS2 deletion in the bone marrow-derived cells by transplanting the bone marrow of RGS2 knock-out mice into wild type mice enhanced UUO-induced kidney fibrosis. Overexpression of RGS2 in HEK293 cells, a human embryonic kidney cell line, and RAW264.7 cells, a monocyte/macrophage line, inhibited the AngII-induced activation of ERK and increase of CXCR4 expression. These findings provide the first evidence that RGS2 negatively regulates the progression of kidney fibrosis following UUO, likely by suppressing fibrogenic and inflammatory responses through the inhibition of AngII/AT1R signaling.

Molecular mechanism of protopanaxadiol saponin fraction-mediated anti-inflammatory actions

Background

Korean Red Ginseng (KRG) is a representative traditional herbal medicine with many different pharmacological properties including anticancer, anti-atherosclerosis, anti-diabetes, and anti-inflammatory activities. Only a few studies have explored the molecular mechanism of KRG-mediated anti-inflammatory activity.

Methods

We investigated the anti-inflammatory mechanisms of the protopanaxadiol saponin fraction (PPD-SF) of KRG using in vitro and in vivo inflammatory models.

Results

PPD-SF dose-dependently diminished the release of inflammatory mediators [nitric oxide (NO), tumor necrosis factor-α, and prostaglandin E₂], and downregulated the mRNA expression of their corresponding genes (inducible NO synthase, tumor necrosis factor-α, and cyclooxygenase-2), without altering cell viability. The PPD-SF-mediated suppression of these events appeared to be regulated by a blockade of p38, c-Jun N-terminal kinase (JNK), and TANK (TRAF family member-associated NF-kappa-B activator)-binding kinase 1 (TBK1), which are linked to the activation of activating transcription factor 2 (ATF2) and interferon regulatory transcription factor 3 (IRF3). Moreover, this fraction also ameliorated HCl/ethanol/-induced gastritis via suppression of phospho-JNK2 levels.

Conclusion

These results strongly suggest that the anti-inflammatory action of PPD-SF could be mediated by a reduction in the activation of p38-, JNK2-, and TANK-binding-kinase-1-linked pathways and their corresponding transcription factors (ATF2 and IRF3).

ATF-2/CREB/IRF-3-targeted anti-inflammatory activity of Korean red ginseng water extract

ETHNOPHARMACOLOGICAL RELEVANCE

Korean Red Ginseng (KRG) is one of the representative traditional herbal medicines prepared from Panax ginseng Meyer (Araliaceae) in Korea. It has been reported that KRG exhibits a lot of different biological actions such as anti-aging, anti-fatigue, anti-stress, anti-atherosclerosis, anti-diabetic, anti-cancer, and anti-inflammatory activities. Although systematic studies have investigated how KRG is able to ameliorate various inflammatory diseases, its molecular inhibitory mechanisms had not been carried out prior to this study.

MATERIALS AND METHODS

In order to investigate these mechanisms, we evaluated the effects of a water extract of Korean Red Ginseng (KRG-WE) on the in vitro inflammatory responses of activated RAW264.7 cells, and on in vivo gastritis and peritonitis models by analyzing the activation events of inflammation-inducing transcription factors and their upstream kinases.

RESULTS

KRG-WE reduced the production of nitric oxide (NO), protected cells against NO-induced apoptosis, suppressed mRNA levels of inducible NO synthase (iNOS), cyclooxygenase (COX)-2, and interferon (IFN)-β, ameliorated EtOH/HCl-induced gastritis, and downregulated peritoneal exudate-derived NO production from lipopolysaccharide (LPS)-injected mice. The inhibition of these inflammatory responses by KRG-WE was regulated through the suppression of p38, c-Jun N-terminal kinase (JNK), and TANK-binding kinase 1 (TBK1) and by subsequent inhibition of activating transcription factor (ATF)-2, cAMP response element-binding protein (CREB), and IRF-3 activation. Of ginsensides included in this extract, interestingly, G-Rc showed the highest inhibitory potency on IRF-3-mediated luciferase activity.

CONCLUSION

These results strongly suggest that the anti-inflammatory activities of KRG-WE could be due to its inhibition of the p38/JNK/TBK1 activation pathway.

Anti-inflammatory activities and mechanisms of Artemisia asiatica ethanol extract

ETHNOPHARMACOLOGICAL RELEVANCE

Artemisia asiatica Nakai (Compositae) is a representative herbal plant used to treat infection and inflammatory diseases. Although Artemisia asiatica is reported to have immunopharmacological activities, the mechanisms of these activities and the effectiveness of Artemisia asiatica preparations in use are not known.

MATERIALS AND METHODS

To evaluate the anti-inflammatory activities of Artemisia asiatica ethanol extract (Aa-EE), we assayed nitric oxide (NO), tumor necrosis factor (TNF)-α, and prostaglandin E2 (PGE2) in macrophages and measured the extent of tissue injury in a model of gastric ulcer induced in mice by treatment with HCl in EtOH. Putative enzymatic mediators of Aa-EE activities were identified by nuclear fractionation, reporter gene assay, immunoprecipitation, immunoblotting, and kinase assay. Active compound in Aa-EE was identified using HPLC.

RESULTS

Treatment of RAW264.7 cells and peritoneal macrophages with Aa-EE suppressed the production of NO, PGE2, and TNF-α in response to lipopolysaccharide (LPS) and induced heme oxygenase-1 expression. The Aa-EE also ameliorated symptoms of gastric ulcer in HCl/EtOH-treated mice. These effects were associated with the inhibition of nuclear translocation of nuclear factor (NF)-κB and activator protein (AP)-1, implying that the anti-inflammatory action of the Aa-EE occurred through transcriptional inhibition. The upstream regulatory signals Syk and Src for translocation of NF-κB and TRAF6 for AP-1 were identified as targets of this effect. Analysis of Aa-EE by HPLC revealed the presence of luteolin, known to inhibit NO and PGE2 activity.

CONCLUSION

The anti-inflammatory activities attributed to Artemisia asiatica Nakai in traditional medicine may be mediated by luteolin through inhibition of Src/Syk/NF-κB and TRAF6/JNK/AP-1 signaling pathways.

(5-Hydroxy-4-oxo-4H-pyran-2-yl)methyl 6-hydroxynaphthalene-2-carboxylate, a kojic acid derivative, inhibits inflammatory mediator production via the suppression of Syk/Src and NF-κB activation

Numerous derivatives of kojic acid have been synthesised to expand its immunopharmacological uses. Kojic acid is known to have anti-cancer, anti-inflammatory, and anti-melanogenesis effects. We found that (5-hydroxy-4-oxo-4H-pyran-2-yl)methyl 6-hydroxynaphthalene-2-carboxylate (MHNC) strongly suppressed the production of nitric oxide (NO) in an initial screening experiment. In this study, we explored the in vitro and in vivo anti-inflammatory activity of MHNC and its inhibitory mechanisms using lipopolysaccharide (LPS)-treated RAW264.7 cells and HCl/EtOH-treated ICR mice. MHNC dose-dependently diminished the secretion of nitric oxide (NO) and prostaglandin (PG)E2 in LPS-treated RAW264.7 cells. This compound also suppressed the upregulation of mRNA levels for the inducible NO synthase (iNOS) and cyclooxygenase (COX)-2 genes. Additionally, the transcriptional activation of these genes was inhibited by MHNC through the suppression of the nuclear translocation of nuclear factor (NF)-κB subunits (p65 and p50), as determined by a luciferase reporter assay. Interestingly, MHNC treatment was found to suppress a series of upstream signalling cascades consisting of IκBα, AKT, PDK1, Src, and Syk for NF-κB activation. Furthermore, a direct enzyme assay with purified Src and Syk and luciferase assays using Src and Syk overexpression indicated that these enzymes were directly inhibited by MHNC. Finally, MHNC (20mg/kg) prevented inflammatory symptoms of the stomach in mice treated with HCl/EtOH by reducing phospho-IκBα levels. Taken together, our data suggest that MHNC may negatively modulate in vitro and in vivo inflammatory responses via the direct suppression of Syk/Src and NF-κB.

Inhibitory effects of epigallocatechin-3-gallate on microsomal cyclooxygenase-1 activity in platelets

In this study, we investigated the effect of (–)-epigallocatechin-3-gallate (EGCG), a major component of green tea catechins from green tea leaves, on activities of cyclooxygenase (COX)-1 and thromboxane synthase (TXAS), thromboxane A₂ (TXA₂) production associated microsomal enzymes. EGCG inhibited COX-1 activity to 96.9%, and TXAS activity to 20% in platelet microsomal fraction having cytochrome c reductase (an endoplasmic reticulum marker enzyme) activity and expressing COX-1 (70 kDa) and TXAS (58 kDa) proteins. The inhibitory ratio of COX-1 to TXAS by EGCG was 4.8. These results mean that EGCG has a stronger selectivity in COX-1 inhibition than TXAS inhibition. In special, a nonsteroid anti-inflammatory drug aspirin, a COX-1 inhibitor, inhibited COX-1 activity by 11.3% at the same concentration (50 μM) as EGCG that inhibited COX-1 activity to 96.9% as compared with that of control. This suggests that EGCG has a stronger effect than that of aspirin on inhibition of COX-1 activity. Accordingly, we demonstrate that EGCG might be used as a crucial tool for a strong negative regulator of COX-1/TXA₂ signaling pathway to inhibit thrombotic disease-associated platelet aggregation.

p-Terphenyl curtisian E inhibits in vitro platelet aggregation via cAMP elevation and VASP phosphorylation

Mushrooms possess untapped source of enormous natural compounds showing anti-inflammatory, antioxidant and anti-platelet activities. Paxillus curtisii, wild mushroom, is a rich source of curtisian E (CE) reported for neuroprotective effects; however, its anti-platelet effect was unknown. Here, therefore, we investigated the anti-platelet activity of CE in rat platelets. Curtisian E (12.5-200μM) attenuated collagen (2.5μg/ml), thrombin (0.1U/ml) and ADP (10μM) induced platelet aggregation in vitro. Likewise, CE diminished intracellular calcium and adenosine triphosphate (ATP) release in collagen activated platelets. Fibrinogen binding and fibronectin adhesion to platelets were also inhibited. While CE downregulated c-jun N-terminal kinase (JNK), extracellular signal-regulated kinase (ERK), p38, and Akt dose dependently in collagen stimulated platelets, it upregulated intraplatelet cyclic adenosine monophosphate (cAMP) and vasodilator-stimulated-phosphoprotein (VASP) phosphorylation. Protein kinase A inhibitor (H-89) markedly inhibited p-VASP(157) protein expression, suggesting that cAMP-PKA-VASP(157) pathway may mediate its anti-platelet effect and thus CE could be considered as a potential anti-thrombotic agent.

Red ginseng saponin fraction a isolated from korean red ginseng by ultrafiltration on the porcine coronary artery

Red ginseng saponin fraction-A (RGSF-A) contains a high percentage of panaxadiol saponins that were isolated from Korean red ginseng by ultrafiltration. The aim of this study was to elucidate the effects of RGSF-A on the porcine distal left anterior descending (LAD) coronary artery. The relaxant responses to RGSF-A were examined during contractions induced by 100 nM U46619 (9,11-dideoxy-9a,11a-methanoepoxy-prostaglandin F2a), a stable analogue of thromboxane A2. RGSF-A dose-dependently induced biphasic (fast- and slow-) relaxation in the distal LAD coronary artery in the presence of an intact endothelium. The fast-relaxation was quickly achieved in a minute, and then the slow-relaxation was slowly developed and sustained for more than thirty minutes after the administration of RGSF-A. The slow-relaxation had a tendency to be bigger than the fast-relaxation. Fast relaxation induced by RGSF-A was almost blocked by N ω-Nitro-L-arginine methyl ester (L-NAME), a nitric oxide synthase inhibitor and 1H-[1,2,4]oxadiazolo[4,3-a]quinoxalin-1-one (ODQ), a guanylate cyclase inhibitor. However slow-relaxation induced by RGSF-A was only partially inhibited by L-NAME and ODQ. In the endothelium-removed ring, RGSF-A evoked only slow-relaxation to a certain extent. These data suggest that RGSF-A induced both endothelium dependent fast- and slow-relaxation and endothelium independent slow-relaxation in the porcine distal LAD coronary artery. The endothelium dependent fast-relaxation is mediated by the nitric oxide (NO)-cGMP pathway, and the endothelium dependent slow-relaxation is at least partially mediated by the NO-cGMP pathway. However, the endothelium-independent slow-relaxation remains to be elucidated.

Inhibitory effects of total saponin from Korean red ginseng via vasodilator-stimulated phosphoprotein-Ser(157) phosphorylation on thrombin-induced platelet aggregation

In this study, we have investigated the effects of total saponin from Korean red ginseng (TSKRG) on thrombin-induced platelet aggregation. TSKRG dose-dependently inhibited thrombin-induced platelet aggregation with IC₅₀ value of about 81.1 μg/mL. In addition, TSKRG dose-dependently decreased thrombin-elevated the level of cytosolic-free Ca²⁺ ([Ca²⁺]_i), one of aggregation-inducing molecules. Of two Ca²⁺-antagonistic cyclic nucleotides as aggregation-inhibiting molecules, cyclic adenosine monophosphate (cAMP) and cyclic guanosine monophosphate (cGMP), TSKRG significantly dose-dependently elevated intracellular level of cAMP, but not cGMP. In addition, TSKRG dose-dependently inhibited thrombin-elevated adenosine triphosphate (ATP) release from platelets. These results suggest that the suppression of [Ca²⁺]_i elevation, and of ATP release by TSKRG are associated with upregulation of cAMP. TSKRG elevated the phosphorylation of vasodilator-stimulated phosphoprotein (VASP)-Ser¹⁵⁷, a cAMP-dependent protein kinase (A-kinase) substrate, but not the phosphorylation of VASP-Ser²³⁹, a cGMPdependent protein kinase substrate, in thrombin-activated platelets. We demonstrate that TSKRG involves in increase of cAMP level and subsequent elevation of VASP-Ser¹⁵⁷ phosphorylation through A-kinase activation to inhibit [Ca²⁺]_i mobilization and ATP release in thrombin-induced platelet aggregation. These results strongly indicate that TSKRG is a beneficial herbal substance elevating cAMP level in thrombin-platelet interaction, which may result in preventing of platelet aggregation-mediated thrombotic diseases.

Korean Red Ginseng Saponin Fraction Downregulates Proinflammatory Mediators in LPS Stimulated RAW264.7 Cells and Protects Mice against Endotoxic Shock

Korean red ginseng has shown therapeutic effects for a number of disease conditions. However, little is known about the antiinflammatory effect of Korean red ginseng saponin fraction (RGSF) in vitro and in vivo. Therefore, in this study, we showed that RGSF containing 20(S)-protopanaxadiol type saponins inhibited nitric oxide production and attenuated the release of tumor necrotic factor (TNF)-α, interleukin (IL)-6, granulocyte monocyte colony stimulating factor (GMCSF), and macrophage chemo-attractant protein-1 in lipopolysaccharide (LPS) stimulated murine macrophage RAW264.7 cells. Moreover, RGSF down-regulated the mRNA expressions of inducible nitric oxide synthase, cyclooxyginase-2, IL-1β, TNF-α, GMCSF, and IL-6. Furthermore, RGSF reduced the level of TNF-α in the serum and protected mice against LPS mediated endotoxic shock. In conclusion, these results indicated that ginsenosides from RGSF and their metabolites could be potential sources of therapeutic agents against inflammation.

Ginsenoside Rp1, a Ginsenoside Derivative, Blocks Promoter Activation of iNOS and COX-2 Genes by Suppression of an IKKβ-mediated NF-кB Pathway in HEK293 Cells

Ginsenoside (G) Rp₁ is a ginseng saponin derivative with anti-cancer and anti-inflammatory activities. In this study, we examined the mechanism by which G-Rp₁ inhibits inflammatory responses of cells. We did this using a strategy in which DNA constructs containing cyclooxygenase (COX)-2 and inducible nitric oxide synthase (iNOS) promoters were transfected into HEK293 cells. G-Rp₁ strongly inhibited the promoter activities of COX-2 and iNOS; it also inhibited lipopolysaccharide induced upregulation of COX-2 and iNOS mRNA levels in RAW264.7 cells. In HEK293 cells G-Rp₁ did not suppress TANK binding kinase 1-, Toll-interleukin-1 receptor-domain-containing adapter-inducing interferon-β (TRIF)-, TRIFrelated adaptor molecule (TRAM)-, or activation of interferon regulatory factor (IRF)-3 and nuclear factor (NF)-кB by the myeloid differentiation primary response gene (MyD88)-induced. However, G-Rp₁ strongly suppressed NF-кB activation induced by IкB kinase (IKK)β in HEK293 cells. Consistent with these results, G-Rp₁ substantially inhibited IKKβ-induced phosphorylation of IкBɑ and p65. These results suggest that G-Rp₁ is a novel anti-inflammatory ginsenoside analog that can be used to treat IKKβ/NF-кB-mediated inflammatory diseases.

Total saponin from korean red ginseng inhibits thromboxane A2 production associated microsomal enzyme activity in platelets

Ginseng, the root of Panax ginseng Meyer, has been used frequently in traditional oriental medicine and is popular globally. Ginsenosides, which are the saponins in ginseng, are the major components having pharmacological and biological activities, including anti-diabetic and anti-tumor activities. In this study, we investigated the effects of total saponin from Korean red ginseng (TSKRG) on thrombin-produced thromboxane A2 (TXA2), an aggregating thrombogenic molecule, and its associated microsomal enzymes cyclooxygenase (COX)-1 and TXA2 synthase (TXAS). Thrombin (0.5 U/mL) increased TXA2 production up to 169 ng/10(8) platelets as compared with control (0.2 ng/10(8) platelets). However, TSKRG inhibited potently TXA2 production to the control level in a dose-dependent manner, which was associated with the strong inhibition of COX-1 and TXAS activities in platelet microsomes having cytochrome c reductase activity. The results demonstrate TSKRG is a beneficial traditional oriental medicine in platelet-mediated thrombotic diseases via suppression of COX-1 and TXAS to inhibit production of TXA2.

AP-1 pathway-targeted inhibition of inflammatory responses in LPS-treated macrophages and EtOH/HCl-treated stomach by Archidendron clypearia methanol extract

ETHNOPHARMACOLOGICAL RELEVANCE

Archidendron clypearia Jack. (Fabaceae) is a representative ethnomedicinal herbal plant prescribed for various inflammatory diseases such as pharyngolaryngitis and tonsillitis. However, the pharmacology behind this plant's anti-inflammatory properties has not been fully understood. Therefore, in this study, the anti-inflammatory mechanism of a 95% methanol extract (Ac-ME) was explored.

MATERIALS AND METHODS

The anti-inflammatory mechanism of Ac-ME on the AP-1 activation pathway, which plays a critical role in the production of prostaglandin (PG)E2 in RAW264.7 cells and peritoneal macrophages and in induction of acute gastritis caused by HCl/EtOH, was investigated using immunoblotting, immunoprecipitation analyses, and reporter gene activity assays. In particular, enzyme assays and HPLC analysis were employed to identify direct target enzymes of Ac-ME and to detect active chemical components from the plant extract.

RESULTS

Ac-ME clearly reduced the nuclear levels of total and phospho-forms of c-Jun, FRA-1, and ATF-2. Consequently, this extract suppressed both the production of PGE2 in lipopolysaccharide (LPS)-activated RAW264.7 and peritoneal macrophage cells and PGE2-dependent induction of gastritis lesion in stomach under EtOH/HCl exposure. Analysis of AP-1 upstream signalling revealed that the AP-1 activation pathway consisting of IRAK1, TRAF6, TAK1, MKK3/6, and p38 was predominantly inhibited by Ac-ME. Similarly, this extract directly blocked the enzyme activity of IRAK1, indicating that this enzyme is an inhibitory target of Ac-ME and is involved in the suppression of the AP-1 pathway. HPLC analysis showed that quercetin, which inhibits PGE2 production, is an active component in Ac-ME.

CONCLUSION

Ac-ME is an ethnomedicinal remedy with an IRAK1/p38/AP-1-targeted inhibitory property. Since AP-1 is a major inflammation-inducing transcription factor, the therapeutic potential of Ac-ME in other AP-1-mediated inflammatory symptoms will be further tested.

Protective effects of recombinant Brucella abortus Omp28 against infection with a virulent strain of Brucella abortus 544 in mice

The outer membrane proteins (OMPs) of Brucella (B.) abortus have been extensively studied, but their immunogenicity and protective ability against B. abortus infection are still unclear. In the present study, B. abortus Omp28, a group 3 antigen, was amplified by PCR and cloned into a maltose fusion protein expression system. Recombinant Omp28 (rOmp28) was expressed in Escherichia coli and was then purified. Immunogenicity of rOmp28 was confirmed by Western blot analysis with Brucella-positive mouse serum. Furthermore, humoral- or cell-mediated immune responses measured by the production of IgG1 or IgG2a in rOmp28-immunized mice and the ability of rOmp28 immunization to protect against B. abortus infection were evaluated in a mouse model. In the immunogenicity analysis, the mean titers of IgG1 and IgG2a produced by rOmp28-immunized mice were 20-fold higher than those of PBS-treated mice throughout the entire experimental period. Furthermore, spleen proliferation and bacterial burden in the spleen of rOmp28-immunized mice were approximately 1.5-fold lower than those of PBS-treated mice when challenged with virulent B. abortus. These findings suggest that rOmp28 from B. abortus is a good candidate for manufacturing an effective subunit vaccine against B. abortus infection in animals.

Ginsenoside-Rp1 inhibits platelet activation and thrombus formation via impaired glycoprotein VI signalling pathway, tyrosine phosphorylation and MAPK activation

BACKGROUND AND PURPOSE

Ginsenosides are the main constituents for the pharmacological effects of Panax ginseng. Such effects of ginsenosides including cardioprotective and anti-platelet activities have shown stability and bioavailability limitations. However, information on the anti-platelet activity of ginsenoside-Rp1 (G-Rp1), a stable derivative of ginsenoside-Rg3, is scarce. We examined the ability of G-Rp1 to modulate agonist-induced platelet activation.

EXPERIMENTAL APPROACH

G-Rp1 in vitro and ex vivo effects on agonist-induced platelet-aggregation, granule-secretion, [Ca(2+) ](i) mobilization, integrin-α(IIb) β(3) activation were examined. Vasodilator-stimulated phosphoprotein (VASP) and MAPK expressions and levels of tyrosine phosphorylation of the glycoprotein VI (GPVI) signalling pathway components were also studied. G-Rp1 effects on arteriovenous shunt thrombus formation in rats or tail bleeding time and ex vivo coagulation time in mice were determined. KEY RESULT: G-Rp1 markedly inhibited platelet aggregation induced by collagen, thrombin or ADP. While G-Rp1 elevated cAMP levels, it dose-dependently suppressed collagen-induced ATP-release, thromboxane secretion, p-selectin expression, [Ca(2+) ](i) mobilization and α(IIb) β(3) activation and attenuated p38(MAPK) and ERK2 activation. Furthermore, G-Rp1 inhibited tyrosine phosphorylation of multiple components (Fyn, Lyn, Syk, LAT, PI3K and PLCγ2) of the GPVI signalling pathway. G-Rp1 inhibited in vivo thrombus formation and ex vivo platelet aggregation and ATP secretion without affecting tail bleeding time and coagulation time, respectively.

CONCLUSION AND IMPLICATIONS

G-Rp1 inhibits collagen-induced platelet activation and thrombus formation through modulation of early GPVI signalling events, and this effect involves VASP stimulation, and ERK2 and p38(-MAPK) inhibition. These data suggest that G-Rp1 may have therapeutic potential for the treatment of cardiovascular diseases involving aberrant platelet activation.