2013 Volume 30 Issue 5 Pages 199-205
This study examined the pharmacokinetics and pharmacological activities of 6-shoganol, a pungent ingredient of Zingiberis Rhizoma, and its metabolite, 6-paradol. The concentrations of 6-shogaol and 6-paradol in rat plasma determined by LC/MS/MS reached their maximum values (Cmax) at 5 minutes after oral administration of 6-shogaol (10 mg/kg). Both 6-shogaol and 6-paradol were eliminated from the plasma within 2 hours after injection. The plasma concentration of 6-paradol, the metabolite, was about 4 times higher than that of 6-shogaol at all points during blood sampling. Next, pharmacological activities of 6-shogaol and 6-paradol were studied. In vitro experiment revealed that the cyclooxygenase-2-inhibitory activity of 6-paradol was about 6 times stronger than that of 6-shogaol. In vivo experiments, 6-paradol demonstrated significantly stronger anti-inflammatory, analgesic, and antipyretic activities compared to 6-shogaol. These results suggest that 6-shogaol in Zingiberis Rhizoma is metabolized rapidly to 6-paradol and that 6-paradol is the main compound having anti-inflammatory activity.