1. Byakangelicol may inhibit P-gp expressed at the BBB even under in vivo conditions. 2. Byakangelicol can inhibit IL-1beta-induced PGE2 release in A549 cells; this inhibition may be mediated by suppression of COX-2 expression and the activity of COX-2 enzyme, thus it may have therapeutic potential as an anti-inflammatory drug on airway inflammation.