Inhibitory effects of furanocoumarins isolated from the roots of Angelica dahurica on prostaglandin E2 production.

We have isolated five furanocoumarins, byakangelicin, phellopterin, imperatorin, isoimperatorin, and oxypeucedanin methanolate, from the roots of Angelica dahurica (Umbelliferae) and prepared five semi-synthesized compounds by the partial reduction of each isolated furanocoumarin, and the effects of these compounds on lipopolysaccharide (LPS)-induced prostaglandin E2 (PGE2 ) production in rat peritoneal macrophages were examined. Among these compounds, imperatorin showed the most potent inhibitory activity on the LPS-induced PGE2 production. It also inhibited the LPS-induced expressions of cyclooxygenase (COX)-2 and microsomal prostaglandin E synthase (mPGES). These findings suggest that the inhibitory effect of furanocoumarins on the LPS-induced PGE2 production is due to the inhibition of the expression of COX-2 and mPGES.