• Nutrition Research and Practice
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• v.7 no.6
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• pp.423-429
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• 2013

Luteolin is a flavonoid found in abundance in celery, green pepper, and dandelions. Previous studies have shown that luteolin is an anti-inflammatory and anti-oxidative agent. In this study, the anti-inflammatory capacity of luteolin and one of its glycosidic forms, luteolin-7-O-glucoside, were compared and their molecular mechanisms of action were analyzed. In lipopolysaccharide (LPS)-activated RAW 264.7 cells, luteolin more potently inhibited the production of nitric oxide (NO) and prostaglandin E2 as well as the expression of their corresponding enzymes (inducible NO synthase (iNOS) and cyclooxygenase-2 (COX-2) than luteolin-7-O-glucoside. The molecular mechanisms underlying these effects were investigated to determine whether the inflammatory response was related to the transcription factors, nuclear factor (NF)-${\kappa}B$ and activator protein (AP)-1, or their upstream signaling molecules, mitogen-activated protein kinases (MAPKs) and phosphoinositide 3-kinase (PI3K). Luteolin attenuated the activation of both transcription factors, NF-${\kappa}B$ and AP-1, while luteolin-7-O-glucoside only impeded NF-${\kappa}B$ activation. However, both flavonoids inhibited Akt phosphorylation in a dose-dependent manner. Consequently, luteolin more potently ameliorated LPS-induced inflammation than luteolin-7-O-glucoside, which might be attributed to the differentially activated NF-${\kappa}B$/AP-1/PI3K-Akt pathway in RAW 264.7 cells.

• Molecules and Cells
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• v.28 no.3
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• pp.201-207
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• 2009

Silibinin is a polyphenolic flavonoid compound isolated from milk thistle (Silybum marianum), with known hepatoprotective, anticarcinogenic, and antioxidant effects. Herein, we show that silibinin inhibits receptor activator of $NF-{\kappa}B$ ligand (RANKL)-induced osteoclastogenesis from RAW264.7 cells as well as from bone marrow-derived monocyte/macrophage cells in a dose-dependent manner. Silibinin has no effect on the expression of RANKL or the soluble RANKL decoy receptor osteoprotegerin (OPG) in osteoblasts. However, we demonstrate that silibinin can block the activation of $NF-{\kappa}B$, c-Jun N-terminal kinase (JNK), p38 mitogen-activated protein (MAP) kinase, and extracellular signal-regulated kinase (ERK) in osteoclast precursors in response to RANKL. Furthermore, silibinin attenuates the induction of nuclear factor of activated T cells (NFAT) c1 and osteoclast-associated receptor (OSCAR) expression during RANKL-induced osteoclastogenesis. We demonstrate that silibinin can inhibit $TNF-{\alpha}$-induced osteoclastogenesis as well as the expression of NFATc1 and OSCAR. Taken together, our results indicate that silibinin has the potential to inhibit osteoclast formation by attenuating the downstream signaling cascades associated with RANKL and $TNF-{\alpha}$.

• The Korean Journal of Physiology and Pharmacology
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• v.22 no.5
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• pp.467-479
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• 2018

The aging process induces a plethora of changes in the body including alterations in hormonal regulation and metabolism in various organs including the heart. Aging is associated with marked increase in the vulnerability of the heart to ischemia-reperfusion injury. Furthermore, it significantly hampers the development of adaptive response to various forms of conditioning stimuli (pre/post/remote conditioning). Aging significantly impairs the activation of signaling pathways that mediate preconditioning-induced cardioprotection. It possibly impairs the uptake and release of adenosine, decreases the number of adenosine transporter sites and down-regulates the transcription of adenosine receptors in the myocardium to attenuate adenosine-mediated cardioprotection. Furthermore, aging decreases the expression of peroxisome proliferator-activated receptor gamma co-activator 1-alpha ($PGC-1{\alpha}$) and subsequent transcription of catalase enzyme which subsequently increases the oxidative stress and decreases the responsiveness to preconditioning stimuli in the senescent diabetic hearts. In addition, in the aged rat hearts, the conditioning stimulus fails to phosphorylate Akt kinase that is required for mediating cardioprotective signaling in the heart. Moreover, aging increases the concentration of $Na^+$ and $K^+$, connexin expression and caveolin abundance in the myocardium and increases the susceptibility to ischemia-reperfusion injury. In addition, aging also reduces the responsiveness to conditioning stimuli possibly due to reduced kinase signaling and reduced STAT-3 phosphorylation. However, aging is associated with an increase in MKP-1 phosphorylation, which dephosphorylates (deactivates) mitogen activated protein kinase that is involved in cardioprotective signaling. The present review describes aging as one of the major confounding factors in attenuating remote ischemic preconditioning-induced cardioprotection along with the possible mechanisms.

• Molecules and Cells
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• v.26 no.1
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• pp.41-47
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• 2008

Mitogen-activated protein kinase (MAPK) signaling is a crucial component of eukaryotic cells; it plays an important role in responses to extracelluar stimuli and in the regulation of various cellular activities. The signaling cascade is evolutionarily conserved in the eukaryotic kingdom from yeast to human. In response to a variety of extracellular signals, MAPK activity is known to be regulated via phosphorylation of a conserved $T{\times}Y$ motif at the activation loop in which both threonine and tyrosine residues are phosphorylated by the upstream kinase. However, the mechanism by which both residues are phosphorylated continues to remain elusive. In the budding yeast, Saccharomyces cerevisiae, Fus3 MAPK is involved in the mating signaling pathway. In order to elucidate the functional mechanism of MAPK activation, we quantitatively profiled phosphorylation of the $T{\times}Y$ motif in Fus3 using mass spectrometry (MS). We used synthetic heavy stable isotope-labeled phosphopeptides and nonphosphopeptides corresponding to the proteolytic $T{\times}Y$ motif of Fus3 and accompanying data-dependent tandem MS to quantitatively monitor dynamic changes in the phosphorylation events of MAPK. Phosphospecific immunoblotting and the MS data suggested that the tyrosine residue is dynamically phosphorylated upon stimulation and that this leads to dual phosphorylation. In contrast, the magnitude of threonine phosphorylation did not change significantly. However, the absence of a threonine residue leads to hyperphosphorylation of the tyrosine residue in the unstimulated condition, suggesting that the threonine residue contributes to the control of signaling noise.

• Natural Product Sciences
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• v.14 no.3
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• pp.182-186
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• 2008

Scutellaria baicalensis Georgi (SBG) is traditionally used medicinal herb that has anti-oxidant, anticancer and anti-inflammatory effects. In this study, we investigated whether the extracts of SBG have the inhibitory activity in the osteoclast differentiation by using mouse monocytes RAW264.7 cells and primary mouse bone marrow-derived macrophages (BMMs). Methanol extract (ME) from SBG was successively fractionated into methylene chloride (MF), ethylacetate (EF) and n-butanol fraction (BF). The activity assay for tartrateresistant acid phosphatase (TRAP) and Western blot analysis were employed to evaluate the osteoclasts differentiation and the activation of mitogen-activated protein (MAP) kinases, respectively. ME, MF, EF and BF significantly and dose-dependently inhibited osteoclast differentiation without the decrease of cell viability at the concentrations used in this study. In addition, ME significantly inhibited the activation of c-jun-N-terminal kinase (JNK). In conclusion, this study firstly demonstrated that ME of SBG has the potential to inhibit the osteoclast differentiation through the suppression of JNK activation partially.

• Journal of Physiology & Pathology in Korean Medicine
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• v.26 no.3
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• pp.293-300
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• 2012

Inducible nitric oxide synthase (iNOS) and cyclooxygenase-2 (COX-2) are important inflammatory mediators implicated in pathogenesis of inflammation and certain types of human cancers. The present study was designed to determine whether Red Ginseng (RG) could modulate $I{\kappa}B$-kinase, iNOS and COX-2 gene expression and immune responses in RAW 264.7 macrophages stimulated with lipopolysaccharide (LPS). RG extract suppressed the expression of LPS-induced $I{\kappa}B$, iNOS, COX-2, and immune responses in a dose-dependent manner. It also showed an anti-inflammatory effect by inhibiting NF-${\kappa}B$ immune response induced by LPS treatment. Inhibitory effect of RG on LPS-induced inflammation was mediated by suppressed phosphorylation of ERK, JNK and p38 through the regulation of the mitogen-activated protein kinase (MAPK) pathway leading to a decreased production of NO, iNOS, COX-2 and NF-${\kappa}B$. The results implied the role of RG as an inflammation regulator and its possible application for curing inflammatory diseases.

• Journal of Physiology & Pathology in Korean Medicine
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• v.24 no.3
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• pp.410-415
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• 2010

The purpose of this study was to investigate the anti-inflammatory effects of aqueous extract from Belamcanda chinensis (BC) on the RAW 264.7 cells. To evaluate the anti-inflammatory effects of BC, we examined the cytokine productions including nitric oxide (NO), interleukin (IL)-1b, IL-6 and tumor necrosis factor-a (TNF-a) in lipopolysaccharide (LPS)-induced RAW 264.7 cells and also inhibitory mechanisms such as mitogen-activated protein kinases (MAPKs) and nuclear factor kappa B (NF-kB) using Western blot. BC inhibited LPS-induced production of NO, IL-6 and TNF-a but not of IL-1b in RAW 264.7 cells. BC respectively inhibited the activation of MAPKs such as c-Jun NH2-terminal kinase (JNK) and p38 but not of extracelluar signal-regulated kinase (ERK 1/2) and NF-kB in the LPS-stimulated RAW 264.7 cells. Taken together, Our results showed that BC down-regulated LPS-induced NO, IL-6 and TNF-a productions mainly through JNK and p38 MAPK pathway.

• YAKHAK HOEJI
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• v.56 no.1
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• pp.26-34
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• 2012

Mast cells play an important role in early and late phase allergic reactions through allergen and IgE-dependent release of histamine, proteases, prostaglandins, and several multifunctional cytokines. In this study, we investigated whether Cudrania tricuspidata extract (CTE) suppresses IgE-mediated allergic responses in mast cells, an allergic animal model, and its mechanism of action in mast cells. We found that CTE inhibited IgE-mediated degranulation and cytokine production in rat basophilic leukemia (RBL)-2H3 mast cells and bone marrow-derived mast cells (BMMC), as well as passive cutaneous anaphylaxis (PCA) in mice. With regard to its mechanism of action, CTE suppressed the activating phosphorylation of spleen tyrosine kinase (Syk), a key enzyme in mast cell signaling processes and that of LAT, a downstream adaptor molecule of Syk in $Fc{\varepsilon}RI$-mediated signal pathways. CTE also suppressed the activating phosphorylation of mitogen-activated protein (MAP) kinases and Akt. The present results strongly suggest that the anti-allergic activity of CTE is mediated through inhibiting degranulation and allergic cytokine secretion by inhibition of Syk kinase in mast cells. Therefore, CTE may be useful for the treatment of allergic diseases.

• BMB Reports
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• v.45 no.8
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• pp.482-487
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• 2012

To identify the novel inhibitors of endoplasmic reticulum stress-induced cell death, we performed a high throughput assay with a chemical library containing a total of 3,280 bioactive small molecules. Cyclosporine A and bromocriptine were identified as potent inhibitors of thapsigargiin-induced cell death (cut-off at $4{\sigma}$ standard score). However, U74389G, the potent inhibitor of lipid peroxidation had lower activity in inhibiting cell death. The inhibition effect of cyclosporine A and bromocriptine was specific for only thapsigargin-induced cell death. The mechanism of inhibition by these compounds was identified as modification of the expression of glucose regulated protein-78 (GRP-78/Bip) and inhibition of phosphorylation of p38 mitogen activated protein kinase (MAPK). However, these compounds did not inhibit the same events triggered by tunicamycin, which was in agreement with the cell survival data. We suggest that the induction of protective unfolded protein response by these compounds confers resistance to cell death. In summary, we identified compounds that may provide insights on cell death mechanisms stimulated by ER stress.

• Journal of Acupuncture Research
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• v.32 no.3
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• pp.83-93
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• 2015

Objectives : The purpose of this study was to evaluate whether acupuncture at $SP_6$ attenuates esophageal inflammation on refluxed-induced esophagitis. Methods : Acupuncture at $SP_6$ was stimulated by acupuncture torsion technique for 30 seconds four times every hour after an operation induced reflux esophagitis(RE), and its effects were assessed in comparison with RE rats without acupuncture, and normal rats. Results : $SP_6$ acupuncture stimulation markedly ameliorated mucosal damage in the histological evaluation. Reflux-induced esophagitis rats exhibited the down-regulation of antioxidant-related protein expression levels such as heme oxygenase-1(HO-1) in the esophagitis; however, the associated levels with $SP_6$ acupuncture stimulation were significantly higher than those in RE rats without acupuncture stimulation. Moreover, $SP_6$ acupuncture stimulation significantly reduced the expression of inflammatory proteins through mitogen-activated protein kinase(MAPK)-related signaling pathways. The increased protein expressions of inflammatory mediators, cyclooxygenase-2(COX-2) and inducible nitric oxide synthase(iNOS), by nuclear factor-kappa B(NF-kB) activation were significantly suppressed through $SP_6$ acupuncture stimulation. Conclusions : Our findings support the therapeutic evidence for $SP_6$ acupuncture stimulation alleviating the development of esophagitis via regulating inflammation through the activation of the antioxidant pathway.