Inhibition of nitric oxide and tumor necrosis factor-alpha by moutan cortex in activated mouse peritoneal macrophages.

Moutan cortex (MC) is one of the most widely used Oriental herbal medicines for treating inflammatory diseases. In this study, the effect of MC on lipopolysaccharide (LPS) and recombinant interferon-gamma (rIFN-gamma)-induced production of nitric oxide (NO) and tumor necrosis factor (TNF)-alpha were examined using mouse peritoneal macrophages. MC inhibited the LPS/rIFN-gamma-induced expression of inducible nitric oxide synthase (iNOS) and TNF-alpha release. To clarify the mechanism involved, the effect of MC on the activation of nuclear factor (NF)-kappaB was examined. The LPS/rIFN-gamma-induced activation of NF-kappaB was almost completely blocked by MC at 0.5 mg/ml. These findings demonstrate that the inhibition of the LPS/rIFN-gamma-induced production of NO and TNF-alpha by MC is due to the inhibition of NF-kappaB activation.