Antiinflammatory potency of dehydrocurdione, a zedoary-derived sesquiterpene

Objective and Design: Dehydrocurdione, a sesquiterpene isolated from zedoary, was tested for in vivo and in vitro antiinflammatory actions. Materials: Analgesic effect was tested in ICR mice by the acetic acid-induced writhing method. Antipyretic effect was studied in Sprague-Dawley rats treated with baker's yeast. Antiinflammatory activities were tested in Wistar rats with carrageenan-induced paw edema and adjuvant-induced chronic arthritis. In vitro analyses included the capabilities to inhibit cyclooxygenase activity, and to scavenge free radicals as determined by electron paramagnetic resonance (EPR). Results: Oral administration of dehydrocurdione (40 to 300 mg/kg) mitigated the writhing reflex.induced by acetic acid and the fever elicited by baker's yeast. A higher dose (200 mg/kg) of dehydrocurdione was required to inhibit the carrageenan-induced paw edema. Oral administration of dehydrocurdione at 120 mg/kg/day for 12 days significantly reduced chronic adjuvant arthritis. Unlike indomethacin (IC50: 0.1 mu M), dehydrocurdione showed minimal cyclooxygenase inhibition. However, dehydrocurdione (100 mu M to 5 mM) significantly reduced free radical formation from hydrogen peroxide and ferrous iron determined by EPR spectrometry using 5,5'-dimethyl-1-pyrroline-N-oxide as a spin trap agent. Conclusion: In addition to the well-known effect of zedoary as a stomachic, dehydrocurdione, the major component of Curcuma zedoaria Roscoe has antiinflammatory potency related to its antioxidant effect.