Shikonin, an ingredient of Lithospermum erythrorhizon, inhibits angiogenesis in vivo and in vitro

Angiogenesis is critical for tumor growth and inflammation. Shiunko is a Chinese herbal ointment used for the treatment of burns in Japan. Its main ingredient is the root of Lithospermum erythrorhizon, which had been used for treating tumors and inflammation in China since the 5th century. We report here that shikonin, the main chemical ingredient of L. erythrorhizon is a novel inhibitor of angiogenesis. It inhibited tumor necrosis factor-α-induced and B16 melanoma-induced angiogenesis in mice and normal developmental angiogenesis in the yolk-sac membranes of chick embryos. Shikonin also inhibited proliferation and migration of endothelial cells in vitro. The dos-responsive study suggests that the mechanism of this inhibitory effect on angiogenesis involves the prevention of network formation by endothelial cells via blocking integrin α(v)β₃ expression.