Skullcapflavone I from Scutellaria baicalensis induces apoptosis in activated rat hepatic stellate cells

The therapeutic goal in liver fibrosis is the reversal of fibrosis and the selective clearance by apoptosis of hepatic stellate cells (HSCs), which play a central role in liver fibrogenesis. In this study, the apoptotic effect of wogonin, oroxylin A, 2',5,6',7-tetrahydroxyflavone, skullcapflavone I, and baicalein, isolated from the dried root of Scutellaria baicalensis, was investigated in activated rat HSCs, T-HSC/Cl-6 cells transformed with the Simian virus 40. Among the isolated compounds, skullcapflavone I (20 microM for 24 h) significantly induced apoptosis in activated rat HSCs while there was no change in the cell viability of hepatocytes. Skullcapflavone I increased caspase-3 and -9 activities accompanied by the proteolytic cleavage of poly(ADP-ribose) polymerase. Specific inhibitors of caspase-3 and caspase-9 prevented the apoptotic process induced by skullcapflavone I. From these results, skullcapflavone I from S. baicalensis selectively induced apoptosis in T-HSC/Cl-6 cells via caspase-3 and caspase-9 activation.