Tumor necrosis factor-producing activity of wogonin in RAW 264.7 murine macrophage cell line

Wogonin from Scutellaria baicalensis, was demonstrated to increase nitric oxide (NO) in the murine macrophage cell line RAW 264.7. It is our aim to investigate the modulatory effect of wogonin on tumor necrosis factor-alpha (TNF-alpha) gene expression. By using RAW 264.7 as an in vitro model, the effects of wogonin on inducible nitric oxide synthase (NOS2) and TNF-alpha gene expression were evaluated by ELISA and reverse transcribed polymerase chain reaction (RT-PCR). Aspirin and H7 were used to determine the possible signal transduction pathways. The results showed that wogonin at the concentration of 10 (-5) M and 10 (-6) M up-regulated NOS2 gene expression in RAW 264.7 cells. Besides, wogonin up-regulated the gene expression of TNF-alpha, in terms of TNF-alpha secretion and transcription, in a dose dependent manner. The fact that aspirin but not H7 blocks the enhancing effect suggests that NF-kappaB might be involved in wogonin-enhanced TNF-alpha gene expression. We conclude that a low concentration of wogonin up-regulates NOS2 and TNF-alpha gene expression through NF-kappaB pathway.