Abstract
Species of Ephedra plants has been shown to have anti-inflammatory activities. Recently, four alkaloids, ephedrine, pseudoephedrine, ephedroxane, isolated from the crude drug “mao”, and chemically synthesized pseudoephedroxane have been reported to have anti-inflammatory activities. For example, these alkaloids suppressed carrageenin-induced hind-paw edema formation in mice. To elucidate the mechanism of the antiinflammatory activities, the effects of “mao” alkaloids on arachidonic acid release and its metabolism in rat peritoneal macrophages stimulated with zymosan particles were examined. When macrophages were stimulated with zymosan, arachidonic acid release and production of arachidonate metabolites such as prostaglandin (PG) E2, 6-keto-PGF1α, PGF2α, LTB4, and 12-HETE were enhanced. By treatment with dexamethasone, the releace of radioactivity was suppuressed. These four alkaloids also inhibited arachidonic acid release and PGE2 production.
These results suggest that a part of the anti-inflammatory activities by “mao” alkaloids is attributable to their inhibitory effects on arachidonate metabolism.
