[Pharmacological studies on ginger. IV. Effect of (6)-shogaol on the arachidonic cascade]

(6)-Shogaol, a pungent component of ginger, which is contained in semi-dried ginger but is rarely found in fresh ginger inhibited carrageenin-induced swelling of hind paw in rats and arachidonic acid (AA)-induced platelet aggregation in rabbits. Moreover, (6)-shogaol prevented prostaglandin I2 (PGI2) release from the aorta of rats when tested as an inhibitor of platelet aggregation. These results suggest that (6)-shogaol may have an inhibitory action on the cyclo-oxygenases in both platelets and aorta. Examination of the effects of (6)-shogaol on cyclo-oxygenases in rabbit platelets and microsome fractions of rat aorta indicated that (6)-shogaol inhibited cyclo-oxygenase activities of both tissues in a concentration-dependent manner. Furthermore, when we examined the effect of (6)-shogaol on 5-lipoxygenase from RBL-1 cells, (6)-shogaol exhibited an inhibitory action on 5-lipoxygenase activity. Therefore, it seems that the inhibitory effects of (6)-shogaol on the carrageenin-induced paw edema, AA-induced platelet aggregation and PGI2 production of aorta may be caused by the inhibition of cyclo-oxygenase activity.