Anti-inflammatory constituents isolated from Clerodendron trichotomum tunberg leaves (CTL) inhibits pro-inflammatory gene expression in LPS-stimulated RAW 264.7 macrophages by suppressing NF-κB activation

Clerodendron trichotomum Tunberg Leaves (CTL) have been used for centuries in Chinese folk medicine for their anti-inflammatory properties. To investigate the molecular mechanism of anti-inflammation by CTL, we analyzed the regulation of TNF-alpha expression in RAW 264.7 cells, a key step in inflammation. The effect of CTL on the production and expression of tumor necrosis factor-alpha (TNF-alpha) was determined by enzyme-linked immunosorbent assay (ELISA) and reverse transcription polymerase chain reaction (RT-PCR). CTL inhibited the production and expression of TNF-alpha in LPS-stimulated RAW 264.7 cells in a dose-dependent manner. In addition, activation of NF-kappa B, which controls TNF-alpha expression, was inhibited in LPS-stimulated RAW 264.7 cells by CTL in a dose-dependent manner, as demonstrated by an electrophoretic mobility shift assay (EMSA). Furthermore, CTL inhibited activation of NF-kappa B through inhibition of I kappa B degradation, as demonstrated by an western blot analysis of I kappa B-alpha. These results suggest that CTL inhibits the expression of the pro-inflammation gene through the inhibition of NF-kappa B dependent pathway in RAW 264.7 cells.