The inhibitory action of quercetin on lipopolysaccharide-induced nitric oxide production in RAW 264.7 macrophage cells

Abstract

The effect of quercetin on lipopolysaccharide (LPS)-induced nitric oxide (NO) production was studied. Quercetin pretreatment significantly inhibited NO production in an LPS-stimulated RAW 264.7 murine macrophage cell line. Post-treatment with quercetin partially inhibited NO production. The inhibitory action of quercetin was due to neither the cytotoxic action nor altered LPS binding. The expression of inducible-type NO synthase (iNOS) was markedly down-regulated by quercetin. Quercetin suppressed the release of free nuclear factor (NF)-kappaB by preventing degradation of IkappaB-alpha and IkappaB-beta. Moreover, quercetin blocked the phosphorylation of extracellular signal regulated kinase 1/2 (Erk 1/2), p38, and c-Jun NH2-terminal kinase/stress-activated protein kinase (JNK/SAPK) and, further, the activity of tyrosine kinases in LPS-stimulated RAW cells. Quercetin also inhibited interferon (IFN)-gamma-induced NO production. Taken together, these results indicate that the inhibitory action of quercetin on NO production in LPS- and/or IFN-gamma-stimulated macrophages might be due to abrogation of iNOS protein induction by impairment of a series of intracellular signal pathways.

Piceatannol Prevents Lipopolysaccharide (LPS)‐Induced Nitric Oxide (NO) Production and Nuclear Factor (NF)‐κB Activation by Inhibiting IκB Kinase (IKK)

“…RAW 264.7 cells were pretreated with piceatannol for 1 hr in a 35-mm plastic dish (4ϫ10 5 cells/dish) and stimulated with LPS (100 ng/ml) for some time. The immunoblotting method has been described previously (30). Briefly, the cell lysates were extracted by lysis buffer containing 0.5-M Tris-HCl, 4% sodium dodecylsulfate (SDS) and 2 mercaptoethanol, and boiled at 80 C for 5 min.…”

“…In particular, NF-κB is a pivotal regulator of iNOS expression (24,32). Recently, we have characterized the signal transduction for LPSinduced NO production in murine macrophages (7,8,23,30).…”

Anti-inflammatory, anticholinesterase and antioxidant activity of leaf extracts of twelve plants used traditionally to alleviate pain and inflammation in South Africa

“…Extracts with LOX inhibitory activity greater than 50% in a preliminary screening were then tested between 0-128µg/mL in the confirmation assay and they inhibited LOX in a The NO production inhibitory activity of plant extracts were evaluated in LPS-activated malignant macrophages cell line RAW264.7. Validity of the assays was shown by using untreated cells as negative control, LPS-stimulated cells as positive control and additionally a cell group as reduction control group with LPS-stimulated cells, co-incubated together with quercetin used as an inhibitor of NO (Mu et al, 2001). As shown in Table 3, all the extracts showed dose dependent inhibition of NO production at the concentration of 6.25, 12.5, 25 and 50µg/mL.…”

Lipopolysaccharide Prevents Doxorubicin-Induced Apoptosis in RAW 264.7 Macrophage Cells by Inhibiting p53 Activation

“…The immunoblotting method was described previously (24). Briefly, the cell lysates were extracted by lysis buffer containing 0.5 mol/L Tris-HCl, 4% SDS, and 2 mercaptoethanol, and boiled at 80jC for 5 minutes.…”