(-)-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 syntha se was isolated from aerial parts of Celastrus orbiculatus Thunb. (Celastra ceae), an oriental folk medicine for rheumatoid arthritis by activity-guide d column chromatographic methods. The COX inhibitor was identified as (-)-e piafzelechin, a member of flavan-3-ols by the structural analysis with HR-E I-mass, H-1-NMR and C-13-NMR spectral data. The compound exhibited a dose-d ependent inhibition on the COX activity with an IC50 value of 15 mu M. (-)- Epiafzelechin exhibited about 3-fold weaker inhibitory potency on the enzym e activity than indomethacin as a positive control. (-)-Epiafzelechin exhib ited significant anti-inflammatory activity on carrageenin-induced mouse pa w edema when the compound (100 mg/kg) was orally administrated at 1 h befor e carrageenin treatment.