Objective and design: We investigated the effect of a new class of COX-2 inhibitor, rutaecarpine, on the production of PGD2 in bone marrow derived mast cells (BMMC) and PGE2 in COX-2 transfected HEK293 cells. Inflammation was induced by lambda-carrageenan in male Splague-Dawley (SD) rats.

Material: Rutaecarpine (8,13-Dihydroindolo[2',3':3,4]pyridol[2,1-b]quinazolin -5(7H)-one) was isolated from the fruits of Evodia rutaecarpa. BMMC were cultured with WEHI-3 conditioned medium. c-Kit ligand and IL-10 were obtained by their expression in baculovirus.

Methods: The generation of PGD2 and PGE2 were determined by their assay kit. COX-1 and COX-2 protein and mRNA expression was determined by BMMC in the presence of KL, LPS and IL-10.

Treatment: Rutaecarpine and indomethacin dissolved in 0.1% carboxymethyl cellulose was administered intraperitoneally and, 1 h later, lambda-carrageenan solution was injected to right hind paw of rats. Paw volumes were measured using plethysmometer 5 h after lambda-carrageenan injection.

Results: Rutaecarpine inhibited COX-2 and COX-1 dependent phases of PGD2 generation in BMMC in a concentration-dependent manner with an IC50 of 0.28 microM and 8.7 microM, respectively. It inhibited COX-2-dependent conversion of exogenous arachidonic acid to PGE2 in a dose-dependent manner by the COX-2-transfected HEK293 cells. However, rutaecarpine inhibited neither PLA2 and COX-1 activity nor COX-2 protein and mRNA expression up to the concentration of 30 microM in BMMC, indicating that rutaecarpine directly inhibited COX-2 activity. Furthermore, rutaecarpine showed in vivo anti-inflammatory activity on rat lambda-carrageenan induced paw edema by intraperitoneal administration.

Conclusion: Anti-inflammatory activity of Evodia rutaecarpa could be attributed at least in part by inhibition of COS-2.