Inhibition by hydroxyachillin, sesquiterpene lactone from Tanacetum microphyllum, of PMA-induced mouse ear oedema

4-beta-phorbol 12-myristate 13-acetate (PMA), when administered topically to mouse ear, induces a pronounced inflammatory response mediated by protein kinase C (PKC). Activation of PKC is implicated in the pathogenesis of inflammation, with Phospholipase A2-dependent arachidonic acid release and eicosanoid production. We have investigated the effects of hydroxyachillin, a sesquiterpene lactone from Tanacetum microphyllum DC., on mouse ear oedema induced by PMA. The effects of this compound on swelling and Other inflammatory parameters are described. Hydroxyachillin significantly (p < or = 0.01) inhibited ear swelling in a dose-dependent manner, and was as effective as the reference drugs. The PMA-induced vascular permeability was significantly (p < or = 0.05) reduced by hydroxyachillin at the highest dose (3 mg/ear). Histologically, the signs of inflammation were greatly reduced in the hydroxyachillin-treated ear lesions. These data suggest that hydroxyachillin is an effective anti-inflammatory agent in this model, and that the inhibition of PKC may be one of the mechanisms of hydroxyachillin's effect.