体外柴胡皂苷元d对C_6大鼠神经胶质瘤细胞前列腺素E_2生成的影响

目的　观察柴胡皂苷元d(saikogenind ,SGD)对C6大鼠神经胶质瘤细胞体外前列腺素E2 (PGE2 )生成的影响。方法　用放射性免疫法测定细胞产生的PGE2 ,液体闪烁测量法测定14 C花生四烯酸 (AA)标记细胞释放14 C AA。结果　SGD在 1～ 2 0 μmol·L-1范围内 ,抑制由钙离子载体A2 3187诱发C6大鼠神经胶质瘤细胞前列腺素E2 (prostaglandinE2 ,PGE2 )释放 ,其IC50 为 3μmol·L-1,但对花生四烯酸 (arachi donicacid ,AA)释放无影响。SGD不影响细胞微粒体组分将AA转化为PGE2 。结论　SGD抑制由钙离子载体A2 3187诱发体外C6大鼠神经胶质瘤细胞PGE2 产生 ,但不抑制AA释放和直接抑制环氧脂酶 (cyclooxygenase ,COX)活性。     

Inhibition of prostaglandin E(2) production by taiwanin C isolated from the root of Acanthopanax chiisanensis and the mechanism of action

Five lignans, l-sesamin, savinin, helioxanthin, taiwanin C, and cis-dibenzylbutyrolactone, were isolated from the root of Acanthopanax chiisanensis (Araliaceae), a Korean medicinal plant, and their inhibitory effects on the production of prostaglandin (PG) E(2) stimulated by 12-O-tetradecanoylphorbol 13-acetate (TPA) in rat peritoneal macrophages were examined. Among the five lignans, taiwanin C was the most potent (IC(50)=0.12 microM), followed by helioxanthin, cis-dibenzylbutyrolactone, and savinin. l-Sesamin had no effect. Taiwanin C showed no inhibitory effect on the TPA-induced release of radioactivity from [3H]arachidonic acid-labeled macrophages, nor did it inhibit the expression of cyclooxygenase (COX)-2 protein induced by TPA. However, the activities of isolated COX-1 and COX-2 were inhibited by taiwanin C (IC(50)=1.06 and 9.31 microM, respectively), reflecting the inhibition of both COX-1- and COX-2-dependent PGE(2) production in the cell culture system. These findings suggest that the mechanism of action of taiwanin C in the inhibition of PGE(2) production is the direct inhibition of COX enzymatic activity.     

Inhibition of prostalglandin E2 production by 2'-hydoxychalcone derivatives and the mechanism of action

The effects of 14 synthetic 2'-hydroxychalcone derivatives on prostaglandin E2 (PGE2) production in rat peritoneal macrophages stimulated by the protein kinase C activator, 12-O-tetradecanoylphorbol 13-acetate (TPA), were examined to clarify the structure-activity relationship. 2',4-Dihydroxy-4'-methoxychalcone (compound 3), 2',4-dihydroxy-6'-methoxychalcone (compound 8) and 2'-hydroxy-4'-methoxychalcone (compound 9) suppressed PGE2 production more potently than the other compounds. The IC50 (50% Inhibitory concentration) value for compounds 3, 8 and 9 was calculated to be 3 microM. The activity of cyclooxygenase (COX)-1 was inhibited slightly by compound 9, but that of COX-2 was not inhibited. At concentrations that inhibited the production of PGE2, compound 9 had no effect on the release of radioactivity from [3H]arachidonic acid-labelled macrophages stimulated by TPA. Western-blot analysis revealed that the induction of COX-2 protein by TPA was inhibited by compound 9 in parallel with the inhibition of PGE2 production. Compounds 3 and 8 had similar effects. These findings suggest that 4'-methoxyl and 6'-methoxyl groups are required for the expression of more potent inhibitory activity against PGE2 production, and that the inhibition of PGE2 production by these 2'-hydroxychalcone derivatives is due to the inhibition of TPA-induced COX-2 protein expression.     

Effects of caffeine and paracetamol alone or in combination with acetylsalicylic acid on prostaglandin E(2) synthesis in rat microglial cells

Paracetamol has mild analgesic and antipyretic properties and is, along with acetylsalicylic acid, one of the most popular "over the counter" analgesic agents. However, the mechanism underlying its clinical effects is unknown. Another drug whose mechanism of action is unknown is caffeine, which is often used in combination with other analgesics, augmenting their effect. We investigated the inhibitory effect of paracetamol and caffeine on lipopolysaccharide (LPS)-induced cyclooxygenase (COX)- and prostaglandin (PG)E(2)-synthesis in primary rat microglial cells and compared it with the effect of acetylsalicylic acid, salicylic acid, and dipyrone. Furthermore, combinations of these drugs were used to investigate a possible synergistic inhibitory effect on PGE(2)-synthesis. Both paracetamol (IC(50)=7.45 microM) and caffeine (IC(50)=42.5 microM) dose-dependently inhibited microglial PGE(2) synthesis. In combination with acetylsalicylic acid (IC(50)=3.12 microM), both substances augmented the inhibitory effect of acetylsalicylic acid on LPS-induced PGE(2)-synthesis. Whereas paracetamol inhibited only COX enzyme activity, caffeine also inhibited COX-2 protein synthesis. These results are compatible with the view that the clinical activity of paracetamol and caffeine is due to inhibition of COX. Furthermore, these results may help explain the clinical experience of an adjuvant analgesic effect of caffeine and paracetamol when combined with acetylsalicylic acid.     

Inhibitory effect of curcumin, a food spice from turmeric, on platelet-activating factor- and arachidonic acid-mediated platelet aggregation through inhibition of thromboxane formation and Ca2+ signaling.

Curcumin, a dietary spice from turmeric, is known to be anti-inflammatory, anticarcinogenic, and antithrombotic. Here, we studied the mechanism of the antiplatelet action of curcumin. We show that curcumin inhibited platelet aggregation mediated by the platelet agonists epinephrine (200 microM), ADP (4 microM), platelet-activating factor (PAF; 800 nM), collagen (20 microg/mL), and arachidonic acid (AA: 0.75 mM). Curcumin preferentially inhibited PAF- and AA-induced aggregation (IC50; 25-20 microM), whereas much higher concentrations of curcumin were required to inhibit aggregation induced by other platelet agonists. Pretreatment of platelets with curcumin resulted in inhibition of platelet aggregation induced by calcium ionophore A-23187 (IC50; 100 microM), but curcumin up to 250 microM had no inhibitory effect on aggregation induced by the protein kinase C (PKC) activator phorbol myrsitate acetate (1 microM). Curcumin (100 microM) inhibited the A-23187-induced mobilization of intracellular Ca2+ as determined by using fura-2 acetoxymethyl ester. Curcumin also inhibited the formation of thromboxane A2 (TXA2) by platelets (IC50; 70 microM). These results suggest that the curcumin-mediated preferential inhibition of PAF- and AA-induced platelet aggregation involves inhibitory effects on TXA2 synthesis and Ca2+ signaling, but without the involvement of PKC.     

Inhibition by licochalcone A, a novel flavonoid isolated from liquorice root, of IL-1beta-induced PGE2 production in human skin fibroblasts

Licochalcone A, a novel flavonoid isolated from the root of Glycyrrhiza inflata, has been reported to exhibit anti-inflammatory activity in animal models. In this study, we examined the effect of licochalcone A on the production of chemical mediators such as prostaglandin (PG)E2 and cytokines by interleukin (IL)-1beta in human skin fibroblasts. Licochalcone A (IC50 15.0 nM) inhibited PGE2 production, but not IL-6 and IL-8 production, in response to IL-1beta. NS-398 (IC50 1.6 nM), a COX-2 selective inhibitor, also suppressed the PGE2 production. Furthermore, licochalcone A and NS-398 suppressed PGF(2alpha) production by IL-1beta. However, licochalcone A (1 microM) had no effect on increased levels of cyclooxygenase (COX)-2 mRNA and protein in cells. Dexamethasone (100 nM) not only inhibited PGE2, PGF(2alpha), IL-6 and IL-8 production but also strongly suppressed the expression of COX-2 mRNA and protein. Licochalcone A had no effect on COX-1-dependent PGE2 production, whereas indometacin (100 nM), a dual inhibitor of COX-1 and COX-2, was very effective. These results suggest that licochalcone A induces an anti-inflammatory effect through the inhibition of COX-2-dependent PGE2 production. Furthermore, it appears that the inhibitory effect of licochalcone A on PGE2 production in response to IL-1beta is quite different from that of the steroid.     

The anti-inflammatory effect of FR188582, a highly selective inhibitor of cyclooxygenase-2, with an ulcerogenic sparing effect in rats

The anti-inflammatory and ulcerogenic effects of FR188582, 3-chloro-5-[4-(methylsulfonyl) phenyl]-1-phenyl-1H-pyrazole, were investigated. In a recombinant human cyclooxygenase (COX) enzyme activity, FR188582 inhibited COX-2 with an IC50 value of 0.017 microM, and the inhibition of prostaglandin (PG) E2 formation by FR188582 was over 6000 times more selective for COX-2 than COX-1. Oral administration of FR188582 dose-dependently inhibited adjuvant arthritis. This effect was threefold more potent than that of indomethacin. FR188582 and indomethacin dose-dependently suppressed the formation of immunoreactive PGE2, but not immunoreactive leukotriene (LT) B4, in arthritic paw. Unlike indomethacin, FR188582 did not induce visible gastric lesions in rats at doses up to 32 mg/kg, p.o. Furthermore, FR188582 did not inhibit the level of immunoreactive PGE2 and immunoreactive 6-keto PGF1alpha in rat gastric mucosa. These results suggest that FR188582, a highly selective COX-2 inhibitor, has a potent anti-inflammatory effect mediated by inhibition of PGE2 in inflamed tissues. The safety profile of FR188582 appears to be improved over the safety profile of indomethacin.     

Anti-inflammatory activity of mangostins from Garcinia mangostana.

The fruit hull of Garcinia mangostana Linn (Guttiferae) is used as an anti-inflammatory drug in Southeast Asia. Two xanthones, alpha- and gamma-mangostins, were isolated from the fruit hull of G. mangostana, and both significantly inhibited nitric oxide (NO) and PGE(2) production from lipopolysaccharide (LPS)-stimulated RAW 264.7 cells. The IC(50) values for the inhibition of NO production by alpha- and gamma-mangostins were 12.4 and 10.1 microM, respectively. After iNOS enzyme activity was stimulated by LPS for 12 h, treatment with either alpha- or gamma-mangostin at 5 microg/ml (12.2 and 12.6 microM, respectively) for 24 h did not significantly inhibit NO production. The data show that the inhibitory activities of alpha- and gamma-mangostins are not due to direct inhibition of iNOS enzyme activity. On the other hand, expression of iNOS was inhibited by alpha- and gamma-mangostins in LPS-stimulated RAW 264.7 cells, but not by COX-2. However, the level of PGE(2) production was reduced by the two xanthones. In an in vivo study, alpha-mangostin significantly inhibited mice carrageenan-induced paw edema. In conclusion, alpha- and gamma-mangostins from G. mangostana are bioactive substances with anti-inflammatory effects.     

Petasites hybridus extracts in vitro inhibit COX-2 and PGE2 release by direct interaction with the enzyme and by preventing p42/44 MAP kinase activation in rat primary microglial cells

Rhizomes of butterbur, Petasites hybridus L. (Asteraceae), have been used since ancient times for the treatment of inflammatory diseases. In the present study, the effects of lipophilic extracts from rhizomes of Petasites hybridus on the formation and release of prostaglandin E2 were investigated. The extracts had different contents of petasin and isopetasin: A: 2.1 % and 0.4 %, B: 0.2 % and 0.1 %, C: 12.1 % and 6.1 % and D: 21.9 % and 9.4 %, respectively. Direct inhibition of cyclooxygenase (COX) -1 and -2 isoenzymes and inhibition of the expression of COX-2 and p42/44 MAP kinase in rat primary microglial cells were tested. All extracts were found to be only weak direct inhibitors of COX-1 (IC50> 400 microg/mL). However, most extracts revealed a strong inhibitory activity against the inducible isoform COX-2 ( A: IC50=30.4 microg/mL; B: IC50=60.6 microg/mL; C: IC50=22.6 microg/mL; D: IC50=20.0 microg/mL). This activity was not correlated to the content of petasin and isopetasin. Pure petasin and isopetasin neither inhibited COX-1 nor COX-2 (IC50 > 400 microM for both compounds and enzymes). Petasites extracts dose-dependently inhibited LPS-induced and thus COX-2-mediated PGE2 release in primary rat microglial cells (A: IC50= 2.4 microg/mL; C: IC50=5.8 microg/mL and D: IC50=4.6 microg/mL). Also this effect was independent from the petasin and isopetasin content. COX-2 synthesis in microglia was totally blocked with 5 microg/mL of C whereas COX-1 synthesis was not influenced. C and D did not affect the LPS-induced activation of p38 MAPK and IkappaBalpha, but they prevented the LPS-induced activation of p42/44 MAPK. Therefore, these Petasites hybridus extracts can be regarded as natural selective inhibitors of COX-2 and its expression, an effect which is independent from the petasin content.     

Byakangelicol,isolated from Angelica dahurica,inhibits both the activity and induction of cyclooxygenase-2 in human pulmonary epithelial cells

We examined the inhibitory mechanism of byakangelicol, isolated from Angelica dahurica, on interleukin-1beta (IL-1beta)-induced cyclooxygenase-2 (COX-2) expression and prostaglandin E2 (PGE2) release in human pulmonary epithelial cell line (A549). Byakangelicol (10-50 microM) concentration-dependently attenuated IL-1beta-induced COX-2 expression and PGE2 release. The selective COX-2 inhibitor, NS-398 (0.01-1 microM), and byakangelicol (10-50 microM) both concentration-dependently inhibited the activity of the COX-2 enzyme. Byakangelicol, at a concentration up to 200 microM, did not affect the activity and expression of COX-1 enzyme. IL-1beta-induced p44/42 mitogen-activated protein kinase (MAPK) activation was inhibited by the MAPK/extracellular signal-regulated protein kinase (MEK) inhibitor, PD 98059 (30 microM), while byakangelicol (50 microM) had no effect. Treatment of cells with byakangelicol (50 microM) or pyrrolidine dithiocarbamate (PDTC; 50 microM) partially inhibited IL-1beta-induced degradation of IkappaB-alpha in the cytosol, translocation of p65 NF-kappaB from the cytosol to the nucleus and the NF-kappaB-specific DNA-protein complex formation. Taken together, we have demonstrated that byakangelicol inhibits IL-1beta-induced PGE2 release in A549 cells; this inhibition may be mediated by suppression of COX-2 expression and the activity of COX-2 enzyme. The inhibitory mechanism of byakangelicol on IL-1beta-induced COX-2 expression may be, at least in part, through suppression of NF-kappaB activity. Therefore, byakangelicol may have therapeutic potential as an anti-inflammatory drug on airway inflammation.     

Intracellular platelet-activating factor regulates eicosanoid generation in guinea-pig resident peritoneal macrophages

1. The role of intracellular platelet-activating factor (Paf) in arachidonic acid (AA) mobilization from guinea-pig peritoneal macrophages has been investigated by use of the potent and selective Paf receptor antagonists, WEB 2086 and CV 6209. 2. Adherent macrophages contained cell-associated Paf which was increased by exposure to formyl-methionyl-leucyl-phenylalanine (fMLP), endotoxin and the ionophore, A23187. However, only endotoxin and A23187 caused release of detectable amounts of Paf into the extracellular medium. 3. Exogenous Paf and each of the above stimuli mobilized previously incorporated [14C]-AA and increased the generation of prostacyclin (PGI2) in resident macrophages. 4. WEB 2086 (10-100 microM) and CV 6209 (0.1-10 microM) reduced both basal and stimulated PGI2 generation and WEB 2086 inhibited the mobilization of [14C]-AA. In addition, WEB 2086 (10 microM) inhibited fMLP-and Paf-induced superoxide anion generation. Responses to A23187 were not inhibited by either antagonist. 5. Activation of macrophages by fMLP caused a short burst of intracellular Paf generation but none was detected in the supernatants. The time-course of PGI2 synthesis followed closely that of Paf. 6. These data suggest that intracellular Paf generation is important for subsequent AA mobilization and may have a wider role in signal transduction processes.     

Inhibition of the A-23187-stimulated leukotriene and prostaglandin biosynthesis of rat basophil leukemia (RBL-1) cells by nonsteroidal anti-inflammatory drugs, antioxidants, and calcium channel blockers

Rat basophil leukemia cells (RBL-1), when grown in monolayer, synthesize from endogenous substrates the prostaglandins (PG) E2, F2 alpha, and I2 (measured as 6-keto-PGF1 alpha) and 6-sulfidopeptide-containing leukotrienes (SRS), as well as materials that react serologically with anti-12-hydroxyeicosatetraenoic acid (HETE). The non-steroidal anti-inflammatory drugs indomethacin and aspirin inhibited PGE2 synthesis by RBL-1 cells, which had been stimulated with the calcium ionophore A-23187, in a dose-dependent manner with an IC50 of 0.7 and 7.8 microM respectively. Indomethacin, when used at higher concentrations, also inhibited iSRS synthesis with an IC50 of 230 microM. Benoxaprofen, also a non-steroidal anti-inflammatory drug, inhibited both PGE2 and iSRS production in a dose-dependent manner, but inhibition of the iSRS biosynthesis was three times more effective than inhibition of PGE2 production. The anti-oxidants gossypol, butylated hydroxyanisole (BHA), nordihydroguariatic acid (NDGA), and 3-amino-1-[m-(trifluoromethyl)phenyl]-2-pyrazoline (BW755c) also inhibited iSRS synthesis more effectively than PGE2 biosynthesis. The IC50 values for inhibition of iSRS production were 0.2 microM (gossypol), 0.5 microM (BW755c), 0.6 microM (BHA), and 0.6 microM (NDGA) compared to 2.8 microM (gossypol), 2.0 microM (BW755c), 4.8 microM (BHA) and 2.6 microM (NDGA) for inhibition of PGE2 synthesis. Gossypol, BW755C, BHA, and NDGA, as well as benoxaprofen, inhibited i12-HETE-biosynthesis (IC50 for gossypol, 0.32 microM; and for benoxaprofen, 0.5 microM). Two calcium channel blockers, verapamil and nifedipine, inhibited PGE2, iSRS and i12-HETE synthesis in a dose-dependent manner. The calcium channel blockers inhibited iSRS synthesis ten times more effectively than PGE2 production.     

Selective COX-2 inhibition by a Pterocarpus marsupium extract characterized by pterostilbene, and its activity in healthy human volunteers

In this study, an extract of Pterocarpus marsupium Roxb. containing pterostilbene has been evaluated for its PGE2-inhibitory activity in LPS-stimulated PBMC. In addition, the COX-1/2 selective inhibitory activity of P. marsupium (PM) extract was investigated. Biological activity, as well as safety of PM extract was evaluated in healthy human volunteers. PM extract, pterostilbene and resveratrol inhibited PGE2 production from LPS-stimulated human peripheral blood mononuclear cells (PBMC) with IC50 values of 3.2 +/- 1.3 microg/mL, 1.0 +/- 0.6 microM and 3.2 +/- 1.4 microM, respectively. When pterostilbene content of PM extract is calculated, PGE2 production inhibition of PM extract is comparable to PGE2 production inhibition of purified pterostilbene. Furthermore, in a COX-1 whole blood assay (WBA) PM extract was not effective while in a COX-2 WBA, PM extract decreased PGE2 production indicating COX-2 specific inhibition. In healthy human volunteers, the oral use of 450 mg PM extract did not decrease PGE2 production ex vivo in a WBA. Pterostilbene levels in serum were increased, but were 5-fold lower than the observed IC50 for PGE2 inhibition in LPS-stimulated PBMC. No changes from base-line of the safety parameters were observed and no extract-related adverse events occurred during the study. In conclusion, this is the first study to describe the selective COX-2 inhibitory activity of a Pterocarpus marsupium extract. Moreover, the PGE2 inhibitory activity of PM extract was related to its pterostilbene content. In humans, 450 mg PM extract resulted in elevated pterostilbene levels in serum, which were below the active concentration observed in vitro. In addition, short-term supplementation of 450 mg PM extract is considered to be a safe dose based on the long history of use, the absence of abnormal blood cell counts and blood chemistry values and the absence of extract-related adverse events. This strongly argues for a dose-finding study of PM extract in humans to corroborate the in vitro observed inhibitory activity on PGE2 production in order to resolve the potential use of PM extract in inflammatory disorders and/or inflammatory pain.     

Effects of methyl gallate on arachidonic acid metabolizing enzymes: Cyclooxygenase-2 and 5-lipoxygenase in mouse bone marrow-derived mast cells

Methyl gallate (MG) is a medicinal herbal product that is isolated from Paeonia lactiflora that inhibits cyclooxygenase-2 (COX-2) dependent phases of prostaglandin D2 (PGD2) generation in bone marrow-derived mast cells (BMMC) in a concentration-dependent manner with an IC50 values of 17.0 microM. This compound also found inhibited the COX-2-dependent conversion of the exogenous arachidonic acid to PGD2 in a dose-dependent manner with an IC50 values of 19.0 microM, using a COX enzyme assay kit. However, at concentrations up to 80 microM, MG did not inhibit COX-2 protein expression in BMMC, indicating that MG inhibits COX-2 activity directly. Furthermore, MG consistently inhibited the production of leukotriene C4 (LTC4) in a dose dependent manner, with an IC50 value of 5.3 microM. These results demonstrate that MG has a dual cyclooxygenase-2/5-lipoxygenase inhibitory activity, which might provide the basis for novel anti-inflammatory drugs.     

Inhibition of prostaglandin E2 and superoxide anion production in rat peritoneal macrophages by the calcium antagonists nifedipine and nisoldipine.

In order to clarify the possibility of an antiatherogenic action of the calcium antagonists nifedipine (CAS 21829-25-4) and nisoldipine (CAS 63675-72-9) the effect of nifedipine and nisoldipine on phorbol myristate acetate (PMA)- and calcium ionophore A23187-stimulated O2- and PGE2 production from macrophages was investigated. Nifedipine and nisoldipine inhibited dose-dependently PMA-stimulated O2- and PGE2 production, but not A23187-stimulated PGE2 production. The 50% inhibitory concentration (IC50) of nifedipine and nisoldipine for PMA-stimulated O2- production were 60 and 8 mumol/l, respectively, whereas those for A23187-stimulated O2- were 9.3 and 2.0 mumol/l. IC50 of nifedipine and nisoldipine for PMA-stimulated PGE2 production were 3.0 and 2.8 mumol/l, respectively. The release of [1-14C]-arachidonic acid from labeled macrophages stimulated with PMA was inhibited approximately by 39 to 43% in the presence of 20 mumol/l nifedipine and nisoldipine. The increase of (Ca2+)i in macrophages induced by A23187 could not be attenuated by nifedipine and nisoldipine, and (Ca2+)i level did not alter when stimulated with PMA. These results suggest that the inhibitory mechanism of nifedipine and nisoldipine for O2- production from the macrophages appears to directly inhibit the enzyme system of the NADPH-oxidase complex through the activation of protein kinase C, and that the inhibition of PMA-stimulated PGE2 production may be due to a decrease of phospholipase A2 through protein kinase C. On the basis of the inhibitory action on O2- and PGE2 production from the macrophages, a possible mechanism of antiatherogenic effect of calcium antagonists was discussed.     

Synthesis, structure-activity relationships, and in vivo evaluations of substituted di-tert-butylphenols as a novel class of potent, selective, and orally active cyclooxygenase-2 inhibitors. 2. 1,3,4- and 1,2,4-thiadiazole series

Two isoforms of the cyclooxygenase (COX) enzyme have been identified: COX-1, which is expressed constitutively, and COX-2, which is induced in inflammation. Recently, it has been shown that selective COX-2 inhibitors have antiinflammatory activity and lack the GI side effects typically associated with NSAIDs. Initial mass screening and subsequent SAR studies have identified 6b (PD164387) as a potent, selective, and orally active COX-2 inhibitor. It had IC50 values of 0.14 and 100 microM against recombinant human COX-2 and purified ovine COX-1, respectively. It inhibited COX-2 activity in the J774A.1 cell line with an IC50 of 0.18 microM and inhibited COX-1 activity in platelets with an IC50 of 3.1 microM. The choline salt of compound 6b was also orally active in vivo with an ED40 of 7. 1 mg/kg in the carrageenan footpad edema (CFE) assay. In vivo studies in rats at a dose of 100 mg/kg showed that this compound inhibited gastric prostaglandin E2 (PGE2) production in gastric mucosa by 77% but caused minimal GI damage. SAR studies of this chemical series revealed that the potency and selectivity are very sensitive to minor structural changes.     

Analysis of the mechanism for the anti-inflammatory effect of the anti-rheumatic drug auranofin

Effects of auranofin, an orally active chrysotherapeutic agent, were examined on the production of prostaglandin E2 (PGE2) and nitric oxide (NO) in rat peritoneal macrophages and in RAW 264.7 cells, a murine macrophage-like cell line. Auranofin (1-10 microM) inhibited PGE2 production in rat peritoneal macrophages stimulated with 12-O-tetra-decanoylphorbol 13-acetate (TPA, 16.2 nM) at 8-20 h, but did not affect PGE2 production at 4 h. However, in non-stimulated rat peritoneal macrophages, auranofin increased PGE2 production at 4 h and had no effect on PGE2 production at 8-20 h. It was proved that auranofin (1-10 microM) increased COX (cyclooxygenase)-1-dependent PGE2 production and inhibited COX-2-dependent PGE2 production in rat peritoneal macrophages. Auranofin showed no effect on the enzyme activities of the purified COX-1 and COX-2 proteins. Furthermore, auranofin did not affect the COX-1 protein level, but inhibited the TPA-induced expression of COX-2 protein. Therefore, it was suggested that auranofin inhibited PGE2 production by inhibiting the COX-2 protein induction in TPA-stimulated macrophages. In RAW 264.7 cells, auranofin (0.3-3 microM) inhibited lipopolysaccharide-induced NO synthesis by inhibiting the induction of NO synthase (NOS) protein expression. Auranofin did not affect the enzyme activity of iNOS (inducible NOS). Finally, using rat peritoneal macrophages, the effects of auranofin on PGE2 production and NO production were determined. Auranofin (10 microM) strongly inhibited the production of PGE2 and NO, and the induction of COX-2 protein and NOS protein by TPA. Indomethacin, a COX inhibitor, partially inhibited NO production at the concentration at which PGE2 production was completely inhibited. On the other hand, L-NG-monomethyl-L-arginine acetate (L-NMMA), a NOS inhibitor, partially inhibited PGE2 production. NO production was completely inhibited at the same concentration as shown above. These findings suggest that PGE2 production and NO production partially affect each other. Therefore, the inhibition of PGE2 production by auranofin might be partly due to the inhibition of NO production, and the inhibition of NO production by auranofin be partly due to the inhibition of PGE2 production. In conclusion, auranofin inhibits both PGE2 production and NO production by inhibiting the upregulation of mRNA levels of COX-2 and NOS.     

2-methoxycinnamaldehyde reduces IL-1beta-induced prostaglandin production in rat cerebral endothelial cells

Prostaglandin E2 (PGE2) works as a common final mediator of the febrile. Guizhi-Tang, one of the most famous traditional Chinese medical formula used to treat influenza, common cold and other pyretic conditions, was previously reported to reduce the production of PGE 2 in rats. 2-Methoxycinnamaldehyde is a principle compound isolated from Guizhi-Tang. The aim of the present study was to investigate the effects of 2-methoxycinnamaldehyde on PGE2 production of rat cerebral endothelial cells (CECs). 2-Methoxycinnamaldehyde dose-dependently inhibited interleukin (IL)-1beta-induced PGE2 production in CECs with IC50 values of 174 microM. IL-1beta stimulation increased the protein, activity and mRNA expression of cyclooxygenase (COX)-2 but not COX-1. 2-Methoxycinnamaldehyde reduced IL-1beta-induced protein and activity of COX-2, but did not influence the COX-2 mRNA expression. Our results show that prostaglandin production in CECs during stimulated conditions is sensitive to inhibition by 2-methoxycinnamaldehyde and suggest that 2-methoxycinnamaldehyde may reduce COX-2 protein level and activity but not COX-2 mRNA.     

Dual effect of saikogenin D: in vitro inhibition of prostaglandin E2 production and elevation of intracellular free Ca2+ concentration in C6 rat glioma cells

To clarify the pharmacological profile of saikogenin D, we examined the effect of saikogenin D on prostaglandin E2 (PGE2) production and intracellular free Ca2+ concentration ([Ca2+]i) in C6 rat glioma cells. Saikogenin D (1-20 microM) inhibited PGE2 production induced by the Ca2+ ionophore A23187 in a concentration-dependent manner with the IC50 of about 3 microM. Saikogenin D did not affect the conversion of arachidonic acid into PGE2 in microsomal preparations. On the other hand, saikogenin D elevated [Ca2+]i in a concentration-dependent manner (10-100 microM) with the EC50 value of about 35 microM in the presence or absence of extracellular Ca2+. These results suggest that saikogenin D possesses a dual effect: an inhibition of A23187-induced PGE2 production without a direct inhibition of cyclooxygenase activity; and an elevation of [Ca2+]i that is attributed to Ca2+ release from intracellular stores.