Selective inhibition of 5-lipoxygenase by natural compounds isolated from Chinese plants, Artemisia rubripes Nakai

Three of four natural compounds, which are caffeic acid, eupatilin and 4'-demethyleupatilin, isolated from Chinese plant, Artemisia rubripes Nakai selectively inhibited 5-lipoxygenase of cultured mastocytoma cells. Half-inhibition doses (ID50) for caffeic acid, eupatilin and 4'-demethyleupatilin were 3.7, 14 and 18 X 10(-6) M, respectively. The inhibition by caffeic acid was non-competitive types. Prostaglandin synthase activities were little inhibited by eupatilin and 4'-demethyleupatilin, but rather stimulated by caffeic acid. The formation of leukotriene C4 and D4 by mast tumor cells was almost completely suppressed by these compounds at 10(-4) M.