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The enzymes 5-lipoxygenase and elastase are therapeutic targets in dermatological disorders such as psoriasis. Fifteen extracts from traditional Chinese medicinal plants used to treat topical inflammations were screened for their inhibitory effect on lipoxygenase, cyclooxygenase and elastase activity in intact leukocytes and platelets. Astragalus membranaceus, Forsythia suspensa and Poria cocos inhibited 5-lipoxygenase, with IC50 values of 141, 80 and 141 microg mL(-1), respectively. The latter two species, along with Angelica dahurica and Angelica pubescens, also inhibited elastase (IC50 values of 80, 123, 68 and 93 microg mL(-1), respectively), while A. pubescens, Atractylodes macrocephala, Lentinus edodes, Rehmannia glutinosa and Paeonia lactiflora selectively inhibited 12-(S)-HHTrE production, a valid marker of cyclooxygenase activity. The inhibition of phospholipase A(2) activity by P. cocos is discussed. Dehydrotumulosic and pachymic acids, which have been isolated from P. cocos, were shown to inhibit leukotriene B(4) release. The results indicate that both P. cocos and F. suspensa are potentially valuable species in the management of skin pathologies involving chronic inflammation.

From the galls of Pistacia terebinthus we obtained an extract that proved to be effective against chronic and acute inflammation. Now we report on the isolation and identification of three triterpenes: two tirucallane-type lanostanoids and one oleanane, which we have identified as masticadienonic acid (1), masticadienolic acid (2), and morolic acid (3), respectively. All of them showed effectiveness on the mouse ear inflammation induced by repeated applications of 12-O-tetradecanoylphorbol 13-acetate and on the phospholipase A2-induced foot paw edema. The pharmacological activity of the compounds was ratified by a histological study of the ear samples. In addition, they inhibited leukotriene B4 production in rat polymorphonuclear leukocytes stimulated with calcium ionophore A 23187.

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