Anti-inflammatory activity of prosapogenin methyl ester of platycodin D via nuclear factor-kappaB pathway inhibition.

Platycodin D (PD) isolated from Platycodi Radix has been reported to have anti-inflammatory and anti-tumor activities. In this study, we have investigated anti-inflammatory activities of prosapogenin D (PrsD) and prosapogenin D methyl ester (PrsDMe) of PD. The results indicated that PrsDMe concentration-dependently inhibited lipopolysaccharide (LPS)-induced nitric oxide (NO) and prostaglandin E2 (PGE2) production, however, PrsD did not inhibit NO production in LPS-induced macrophages. Furthermore, PrsDMe inhibited the expression of inducible nitric oxide synthase (iNOS) and cyclooxygenase-2 (COX-2) without appreciable cytotoxic effects. In the transfectant RAW 264.7 cells, PrsDMe was observed to reduce the level of nuclear factor-kappaB (NF-kappaB) activity. PrsDMe also inhibited the degradation of an inhibitory protein called inhibitor kappaB (IkappaB). Therefore, it was suggested that PrsDMe inhibited the expression of LPS-induced iNOS and COX-2 genes by suppressing NF-kappaB activation at the transcriptional level. Also, PrsDMe showed carrageenan-induced acute anti-inflammatory activity and the adjuvant-induced anti-arthritic activity in mice. In conclusion, we suggest that these compounds exert an anti-inflammatory effect through the regulation of the NF-kappaB pathway. The different activities of PD, PrsD and PrsDMe are based on the structure of the sugar substituent or methyl group at the C28-carboxyl position.

SK-126, a synthetic compound, regulates the production of inflammatory cytokines induced by LPS in antigen-presenting cells.

A variety of mediators released by immune cells triggers or enhances specific aspects of the inflammatory response. Dendritic cells (DCs) play an essential role in the innate immune system by shaping the adaptive immune responses and by controlling the production of cytokines in response to inflammatory stimuli. In the present study, we investigated whether SK-126, a pyridine derivative based on gentianine originated from a natural product, can affect the LPS-induced inflammatory cytokine production in DC. Interestingly, treatment of mouse bone marrow-derived dendritic cells (BMDCs) and the murine dendritic cell line, DC 2.4, with SK-126 completely suppressed LPS-induced TNF-alpha expression at both transcriptional and protein levels. In contrast to TNF-alpha, SK-126 enhanced IL-10 expression at both transcriptional and protein levels. To determine signaling pathways involved in the regulation of inflammatory cytokines, we examined the involvement of MAPK and the transcription factor, NF-kappaB. SK-126 enhanced ERK1/2 and p38 activation following LPS stimulation, but it did not induce phosphorylation of SAPK/JNK and NF-kappaB. Also, STAT3 phosphorylation after LPS stimulation was increased by SK-126 to a large extent. Using specific inhibitors, we confirmed that SK-126 has dual effects in which it suppresses TNF-alpha production and enhances IL-10 production via the up-regulation of ERK1/2 and p38. Finally, LPS-induced inflammatory responses such as TNF-alpha production in vivo were significantly reduced by treatment with SK-126. Therefore, our findings suggest that SK-126 may be a useful drug candidate to treat inflammatory diseases in which pro- or anti-inflammatory cytokines play a significant role in their pathogenesis.

Inhibition of lipopolysaccharide-induced iNOS and COX-2 expression by dehydroevodiamine through suppression of NF-kappaB activation in RAW 264.7 macrophages.

Dehydroevodiamine is a major bioactive quinazoline alkaloid isolated from Evodiae Fructus. We investigated the anti-inflammatory properties of dehydroevodiamine in RAW 264.7 murine macrophages. The results indicated that dehydroevodiamine inhibited the expression of LPS-induced iNOS and COX-2 proteins and suppressed also their mRNAs from RT-PCR experiment on RAW 264.7 cells. Furthermore, this compound inhibited the level of LPS-stimulated prostaglandin E2 (PGE2) and LPS-induced nuclear factor-kappa B (NF-kappaB). Therefore, we suggested that the effect of dehydroevodiamine-mediated inhibition of the expression LPS-induced iNOS and COX-2 genes is due to under the suppression of NF-kappaB activation in the transcriptional level.

Inhibitory effects of Irigenin from the rhizomes of Belamcanda chinensis on nitric oxide and prostaglandin E(2) production in murine macrophage RAW 264.7 cells.

In the present study, we investigated antiinflammatory effects of six flavonoids isolated from the rhizomes of Belamcanda chinensis (Iridaceae) in RAW 264.7 macrophages. The results indicated that irigenin concentration dependently inhibited lipopolysaccharide (LPS)-induced nitric oxide (NO) and prostaglandin (PG) E(2) production. Furthermore, this compound inhibited the expression of inducible nitric oxide synthase (iNOS) and cyclooxygenase (COX)-2 proteins and mRNAs without an appreciable cytotoxic effect. Treatment of the transfectant RAW 264.7 cells with irigenin reduced the level of nuclear factor-kappaB (NF-kappaB) activity, also effectively lowered NF-kappaB binding measured by electrophoretic mobility shift assay (EMSA), which was associated with decreased p65 protein levels in the nucleus. On the basis of the above data, we suggest that the effect of irigenin in decreasing LPS-induced NO and PGE(2) synthesis is due to diminish the mRNA and protein expression of iNOS and COX-2, respectively, also may be due to under the suppression of NF-kappaB activation. Therefore, irigenin isolated from the rhizomes of Belamcanda chinensis could be offered as a leading compound for anti-inflammation.

Inhibition of inducible nitric oxide synthase and cyclooxygenase II by Platycodon grandiflorum saponins via suppression of nuclear factor-kappaB activation in RAW 264.7 cells.

Saponins are glycosidic compounds present in many edible and inedible plants. They exhibit potent biological activities in mammalian systems, including several beneficial effects such as anti-inflammation and immunomodulation. In this study, we investigated the effects of seven platycodin saponins on the activities of inducible nitric oxide synthase (iNOS) and cyclooxygenase II (COX-2) in lipopolysaccharide (LPS)-induced RAW 264.7 macrophages. We found that 2"-O-acetyl polygalacin D (S1), platycodin A (S2), platycodin D (S3), and polygalacin D (S6) inhibited LPS-induced NO production in a concentration-dependent manner. Furthermore, these compounds inhibited the expression of LPS-induced iNOS and COX-2 protein and mRNA without an appreciable cytotoxic effect on RAW 264.7 macrophages, and could suppress induction by LPS of pro-inflammatory cytokines such as prostaglandin E2 (PGE2). Treatment with these compounds of RAW 264.7 cells transfected with a reporter construct indicated a reduced level of LPS-induced nuclear factor-kappaB (NF-kappaB) activity and effectively lowered NF-kappaB binding as measured by electrophoretic mobility shift assay (EMSA). The suppression of NF-kappaB activation appears to occur through the prevention of inhibitor kappaB (IkappaB) degradation. In vivo, platycodin saponin mixture (PS) and S3 protected mice from the lethal effects of LPS. The 89% lethality induced by LPS/galactosamine was reduced to 60% and 50% when PS and S3, respectively, were administered simultaneously with LPS. These results suggest that the main inhibitory mechanism of the platycodin saponins may be the reduction of iNOS and COX-2 gene expression through blocking of NF-kappaB activation.