Influence of traditional Chinese anti-inflammatory medicinal plants on leukocyte and platelet functions

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.