Strong antiproliferative effects of baicalein in cultured rat hepatic stellate cells

Recently, antifibrogenetic effects of Sho-saiko-to, a traditional herbal medicine in Japan, have been shown in experimental hepatic fibrosis, and flavonoids in Sho-saiko-to are suspected as active ingredients. Thus, we evaluated the effects of baicalein, a major flavonoid in Sho-saiko-to, on proliferation and protein synthesis in cultured rat hepatic stellate cells. Baicalein decreased [3H]thymidine incorporation in cells stimulated with platelet-derived growth factor-B subunit homodimer (PDGF-BB) in a concentration-dependent manner (approximate ED50<10 microM, P<0.0001), and the decrease observed with 10 microM baicalein was greater than those observed with 5 microM retinol or 500 microM 3-isobutyl-1-methylxanthine (IBMX). Baicalein consistently decreased [3H]thymidine incorporation and cell number in cells stimulated with fetal calf serum (ED50<10 microM, P<0.0001), and moderately suppressed [3H]leucine and [3H]proline incorporation (P<0.0001). These results demonstrate the strong antiproliferative effect of baicalein in hepatic stellate cells, showing the possibility of baicalein as an antifibrogenetic drug for hepatic fibrosis.