We examined the effects of nine flavonoids isolated from Scutellariae radix on interleukin-1 beta (IL-1 beta)- and tumor necrosis factor-alpha (TNF-alpha)-induced adhesion molecule expression in cultured human umbilical vein endothelial cells (HUVECs). Among them, we found that baicalein (5,6,7-trihydroxy flavone) dose-dependently inhibited IL-1 beta and TNF-alpha-induced endothelial leukocyte adhesion molecule-1 (ELAM-1) and intercellular adhesion molecule-1 (ICAM-1) expressions. Its 50% inhibitory concentrations (IC50) for the IL-1 beta-induced ELAM-1 and ICAM-1 expressions were 2.3 x 10(-5) M and 4.0 x 10(-5) M, respectively. The IC50 for the TNF-alpha-induced ELAM-1 and ICAM-1 expressions were 1.5 x 10(-5) M and 3.1 x 10(-5) M, respectively. In addition, protein C-kinase (PKC) inhibitor H7 also inhibited the ELAM-1 and ICAM-1 expressions induced by IL-1 beta and TNF-alpha.