Antiproliferative effect of baicalein, a flavonoid from a Chinese herb, on vascular smooth muscle cell.

The effects of baicalein, baicalin and wogonin, the flavonoids from Scutellaria baicalensis, on the proliferative responses of cultured rabbit vascular smooth muscle cells were studied. The proliferative response was determined from the uptake of tritiated thymidine. In rabbit vascular smooth muscle cells, all three flavonoids dose dependently inhibited the proliferative response induced by 5% fetal calf serum at the dose range of 10(-6) to 10(-4) M. Baicalin and wogonin were less effective than baicalein as inhibitors of the serum-induced smooth muscle cell proliferation, indicating that the three hydroxyl groups on positions 5, 6 and 7 seem to be necessary and sufficient for full inhibitory activity against the proliferative response of smooth muscle cells. Baicalein had a greater inhibitory effect on the proliferative reponse stimulated by platelet-derived growth factor than on serum-stimulated proliferation. Baicalein, a flavonoid with antiproliferative and lipoxygenase-inhibitory activities, may be useful as another template for the development of better drugs to prevent the pathological changes of atherosclerosis and restenosis.