Butanol extract of 1:1 mixture ofPhellodendron cortex andAralia cortex stimulates PI3-kinase and ERK2 with increase of glycogen levels in HepG2 cells

Extracts of Phellodendron amurense Rupr. cortex and Aralia cortex (P55A) have been used traditionally by Koreans to treat diabetes. We tested the extracts of P55A to determine if they could mimic insulin actions such as activation of ERK2, PI3-kinase and glycogen synthesis in liver cells. The butanol extract of P55A activated ERK2 in the cytosol and nucleus of HepG2 cells; the extent of ERK2 activation was much higher in the nucleus. More strikingly, the butanol extract significantly increased the level of glycogen in HepG2 cells. Association of PI3-kinase and IRS-1 in the cytoplasm was also stimulated by the butanol extract of P55A. These results suggest that active component(s) of the butanol extract of P55A could regulate blood glucose levels by activating ERK2 and PI3-kinase and by stimulation of glycogen synthesis in the liver. © 1998 John Wiley & Sons, Ltd.