Anti-inflammatory effect and mechanism of osthole in rats.

OBJECTIVE: To investigate the anti-inflammatory effect and mechanism of osthole (Ost). METHODS: Carrageenan -induced hind paw edema in rats were prepared. The nitric oxide synthase (NOS) activity was measured by NADPH -diaphoras stain assay, nitric oxide (NO) content by Griess diazotization assay, malondialdehyde (MDA) content by Thibabituric acid mehtods. And PG content was assaied by Uv -vis spectrophotometry with 278 nm after 0.5 mol/L KOH methanol reagent dissimilating. RESULTS: The increase in NO2(-) observed 4h after carrageenan administration was inhibited by Ost from 524.4 +/- 58.7/micromol/L(-1) NO2(-) for carrageenan alone to 461.5 +/- 68. 8,353.8 +/- 111.0/micromol/L NO2(-) for, respectively, carrageenan administered in combination with 50 mg/kg or 100 mg/kg Ost. It suggested Ost suppress inflammatory responses on NO levels in a dose -dependent manner (P < 0.05). In the presence of Ost 100 mg/kg, NOS activities remained at near blank control levels. Meanwhile results showed reduced malondialdehyde production (MDA) in the presence of Ost, which is one of the byproducts of lipid peroxidation. Ost 50, 100 mg/kg markedly suppressed the generation of PG in inflamed paws. CONCLUSION: Ost presents anti-inflammatory activities at the used models. The effects may be associated to a supression of content of PG, NO, MDA and cNOS activity by inhibition of calcium entry and elevating cGMP levels way.