Amomum tsao-ko fruit extract suppresses lipopolysaccharide-induced inducible nitric oxide synthase by inducing heme oxygenase-1 in macrophages and in septic mice.

Amomum tsao-ko Crevost et Lemarié (Zingiberaceae) has traditionally been used to treat inflammatory and infectious diseases, such as throat infections, malaria, abdominal pain and diarrhoea. This study was designed to assess the anti-inflammatory effects and the molecular mechanisms of the methanol extract of A. tsao-ko (AOM) in lipopolysaccharide (LPS)-induced RAW 264.7 macrophages and in a murine model of sepsis. In LPS-induced RAW 264.7 macrophages, AOM reduced the production of nitric oxide (NO) by inhibiting inducible nitric oxide synthase (iNOS) expression, and increased heme oxygenase-1 (HO-1) expression at the protein and mRNA levels. Pretreatment with SnPP (a selective inhibitor of HO-1) and silencing HO-1 using siRNA prevented the AOM-mediated inhibition of NO production and iNOS expression. Furthermore, AOM increased the expression and nuclear accumulation of NF-E2-related factor 2 (Nrf2), which enhanced Nrf2 binding to antioxidant response element (ARE). In addition, AOM induced the phosphorylation of extracellular regulated kinase (ERK) and c-Jun N-terminal kinase (JNK) and generated reactive oxygen species (ROS). Furthermore, pretreatment with N-acetyl-l-cysteine (NAC; a ROS scavenger) diminished the AOM-induced phosphorylation of ERK and JNK and AOM-induced HO-1 expression, suggesting that ERK and JNK are downstream mediators of ROS during the AOM-induced signalling of HO-1 expression. In LPS-induced endotoxaemic mice, pretreatment with AOM reduced NO serum levels and liver iNOS expression and increased HO-1 expression and survival rates. These results indicate that AOM strongly inhibits LPS-induced NO production by activating the ROS/MAPKs/Nrf2-mediated HO-1 signalling pathway, and supports its pharmacological effects on inflammatory diseases.

Inhibitory effects of ß-chamigrenal, isolated from the fruits of Schisandra chinensis, on lipopolysaccharide-induced nitric oxide and prostaglandin E2 production in RAW 264.7 macrophages [corrected].

Much is known about the bioactive properties of lignans from the fruits of Schisandra chinensis. However, very little work has been done to determine the properties of sesquiterpenes in the fruits of S. chinensis. The aim of the present study was to investigate the anti-inflammatory potential of new sesquiterpenes (ß-chamigrenal, ß-chamigrenic acid, α-ylangenol, and α-ylangenyl acetate) isolated from the fruits of S. chinensis and to explore their effect on macrophages stimulated with lipopolysaccharide. Of these four sesquiterpenes, ß-chamigrenal most significantly suppressed lipopolysaccharide-induced nitric oxide and prostaglandin E2 production in RAW 264.7 macrophages (47.21 ± 4.54 % and 51.61 ± 3.95 % at 50 µM, respectively). Molecularly, the inhibitory activity of ß-chamigrenal on nitric oxide production was mediated by suppressing inducible nitric oxide synthase activity but not its expression. In the prostaglandin E2 synthesis pathway, ß-chamigrenal prevented the upregulation of inducible microsomal prostaglandin E synthase-1 expression after stimulation with lipopolysaccharide. Conversely, ß-chamigrenal had no effect on the expression and enzyme activity of cyclooxygenase-2. In addition, the expression of early growth response factor-1, a key transcription factor of microsomal prostaglandin E synthase-1 expression, was inhibited by ß-chamigrenal. These results may suggest a possible anti-inflammatory activity of ß-chamigrenal which has to be proven in in vivo experiments.

Echinocystic acid isolated from Eclipta prostrata suppresses lipopolysaccharide-induced iNOS, TNF-α, and IL-6 expressions via NF-κB inactivation in RAW 264.7 macrophages.

In this study, we aimed to identify the compounds in Eclipta prostrata responsible for its anti-inflammatory effects using an in vitro bioassay. Three triterpenoids, eclalbasaponin I, eclalbasaponin II, and echinocystic acid, were isolated from an EtOAc fraction of the 70 % EtOH extract of E. prostrata by activity-guided fractionation based on the inhibition of nitric oxide release from lipopolysaccharide-induced RAW 264.7 macrophages. Of these three triterpenoids, echinocystic acid inhibited lipopolysaccharide-induced production of nitric oxide and cytokines such as tumor necrosis factor-α and interleukin-6. Consistent with these observations, echinocystic acid concentration-dependently inhibited lipopolysaccharide-induced inducible nitric oxide synthase expression at the protein level and inducible nitric oxide synthase, tumor necrosis factor-α, and interleukin-6 expression at the mRNA level, and inhibited lipopolysaccharide-induced iNOS promoter binding activity. In addition, echinocystic acid suppressed the lipopolysaccharide-induced transcriptional activity of nuclear factor-κB by blocking the nuclear translocation of p65.

Fimasartan, anti-hypertension drug, suppressed inducible nitric oxide synthase expressions via nuclear factor-kappa B and activator protein-1 inactivation.

Since inhibition of angiotensin II type 1 (AT1) receptor reduces chronic inflammation associated with hypertension, we evaluated the anti-inflammatory potential and the underlying mechanism of fimasartan, a Korean Food and Drug Administration approved anti-hypertension drug, in lipopolysaccharide (LPS)-stimulated RAW264.7 macrophages. Fimasartan suppressed the expressions of inducible nitric oxide synthase (iNOS) by down-regulating its transcription, and subsequently inhibited the productions of nitric oxide (NO). In addition, fimasartan attenuated LPS-induced transcriptional and DNA-binding activities of nuclear factor-kappa B (NF-κB) and activator protein-1 (AP-1). These reductions were accompanied by parallel reductions in the nuclear translocation of NF-κB and AP-1. Taken together, our data suggest that fimasartan down-regulates the expression of the iNOS in macrophages via NF-κB and AP-1 inactivation.

Euscaphic acid isolated from roots of Rosa rugosa inhibits LPS-induced inflammatory responses via TLR4-mediated NF-κB inactivation in RAW 264.7 macrophages.

As an attempt to search for bioactive natural products exerting anti-inflammatory activity, we have evaluated the anti-inflammatory effects of euscaphic acid (19α-hydroxyursane-type triterpenoids, EA) isolated from roots of Rosa rugosa and its underlying molecular mechanisms in lipopolysaccharide (LPS)-induced RAW 264.7 macrophages. EA concentration-dependently reduced the production of nitric oxide (NO), prostaglandin E2 (PGE2), tumor necrosis factor-α (TNF-α), and interleukin-1ß (IL-1ß) induced by LPS in RAW 264.7 macgophages. Consistent with these data, expression levels of inducible nitric oxide synthase (iNOS) and cyclooxygenase-2 (COX-2) protein and iNOS, COX-2, TNF-α, and IL-1ß mRNA were inhibited by EA in a concentration-dependent manner. In addition, EA attenuated LPS-induced DNA binding and transcriptional activity of nuclear factor-kappa B (NF-κB), which was accompanied by a parallel reduction of degradation and phosphorylation of inhibitory kappa Bα (IκBα) and consequently by decreased nuclear translocation of p65 subunit of NF-κB. Pretreatment with EA significantly inhibited the LPS-induced phosphorylation of IκB kinase ß (IKKß), p38, and JNK, whereas the phosphorylation of ERK1/2 was unaffected. Furthermore, EA interfered with the LPS-induced clustering of TNF receptor-associated factor 6 (TRAF6) with interleukin receptor associated kinase 1 (IRAK1) and transforming growth factor-ß-activated kinase 1 (TAK1). Taken together, these results suggest that EA inhibits LPS-induced inflammatory responses by interference with the clustering of TRAF6 with IRAK1 and TAK1, resulting in blocking the activation of IKK and MAPKs signal transduction to downregulate NF-κB activations.

Potent anti-inflammatory effect of a novel furan-2,5-dione derivative, BPD, mediated by dual suppression of COX-2 activity and LPS-induced inflammatory gene expression via NF-κB inactivation.

BACKGROUND AND PURPOSE: We previously reported that 3-(benzo[d]-1,3-dioxol-5-yl)-4-phenylfuran-2,5-dione (BPD) showed strong inhibitory effects on PGE(2) production. However, the exact mechanism for the anti-inflammatory effect of BPD is not completely understood. In this study, we investigated the molecular mechanism involved in the effects of BPD on inflammatory mediators in LPS-stimulated macrophages and animal models of inflammation. EXPERIMENTAL APPROACH: The expressions of COX-2, inducible NOS (iNOS), TNF-α, IL-6 and IL-1ß, in LPS-stimulated RAW 264.7 cells and murine peritoneal macrophages, were determined by Western blot and/or qRT-PCR, respectively. NF-κB activation was investigated by EMSA, reporter gene assay and Western blotting. Anti-inflammatory effects of BPD were evaluated in vivo in carrageenan-induced paw oedema in rats and LPS-induced septic shock in mice. KEY RESULTS: BPD not only inhibited COX-2 activity but also reduced the expression of COX-2. In addition, BPD inhibited the expression of iNOS, TNF-α, IL-6 and IL-1ß at the transcriptional level. BPD attenuated LPS-induced DNA-binding activity and the transcription activity of NF-κB; this was associated with a decrease in the phosphorylation level of inhibitory κB-α (IκB-α) and reduced nuclear translocation of NF-κB. Furthermore, BPD suppressed the formation of TGF-ß-activated kinase-1 (TAK1)/TAK-binding protein1 (TAB1), which was accompanied by a parallel reduction of phosphorylation of TAK1 and IκB kinase (IKK). Pretreatment with BPD inhibited carrageenan-induced paw oedema and LPS-induced septic death. CONCLUSION AND IMPLICATIONS: Taken together, our data indicate that BPD is involved in the dual inhibition of COX-2 activity and TAK1-NF-κB pathway, providing a molecular basis for the anti-inflammatory properties of BPD.