(-)-Epiafzelechin:: Cyclooxygenase-1 inhibitor and anti-inflammatory agent from aerial parts of Celastrus orbiculatus

An inhibitor of cyclooxygenase (COX)-1 activity of prostaglandin H-2 synthase was isolated from aerial parts of Celastrus orbiculatus Thunb. (Celastraceae), an oriental folk medicine for rheumatoid arthritis by activity-guided column chromatographic methods. The COX inhibitor was identified as (-)-epiafzelechin, a member of flavan-3-ols by the structural analysis with HR-EI-mass, H-1-NMR and C-13-NMR spectral data. The compound exhibited a dose-dependent inhibition on the COX activity with an IC50 value of 15 mu M. (-)-Epiafzelechin exhibited about 3-fold weaker inhibitory potency on the enzyme activity than indomethacin as a positive control. (-)-Epiafzelechin exhibited significant anti-inflammatory activity on carrageenin-induced mouse paw edema when the compound (100 mg/kg) was orally administrated at 1 h before carrageenin treatment.