Inhibition by tectorigenin and tectoridin of prostaglandin E-2 production and cyclooxygenase-2 induction in rat peritoneal macrophages

Tectorigenin and tectoridin, isolated from the rhizomes of Korean Belamcand a chinensis (Iridaceae) which are used as Chinese traditional medicine for the treatment of inflammation, suppressed prostaglandin E-2 production by r at peritoneal macrophages stimulated by the protein kinase C activator, 12- O-tetradecanoylphorbol 13-acetate (TPA), or the endomembrane Ca2+-ATPase in hibitor, thapsigargin. Tectorigenin inhibited prostaglandin E-2 production more potently than tectoridin. Neither compound inhibited the release of ra dioactivity from [H-3]arachidonic acid-labeled macrophages stimulated by TP A or thapsigargin. In addition, activities of isolated cyclooxygenase (COX) -1 and COX-2 were not inhibited by the two compounds. Western blot analysis revealed that the induction of COX-2. by TPA or thapsigargin was inhibited by the two compounds in parallel with the inhibition of prostaglandin Er p roduction. These findings suggest that one of the mechanisms of the anti-in flammatory activities of the rhizomes of Belamcanda chinensis is the inhibi tion of prostaglandin E-2 production by tectorigenin and tectoridin due to the inhibition of the induction of COX-2 in the inflammatory cells. (C) 199 9 Elsevier Science B.V. All rights reserved.