Shikonin is a naphthoquinone found in the Chinese herb Arnebia euchroma （Royle）Johnst and Arnebia guttata Bunge. It inhibits TNF-α- and B6 melanoma-induced angiogenesis in mice. It blocks expression of integrin αvβ3 and inhibits endothelial cell proliferation and migration in vitro.

References:

• Shikonin, a component of chinese herbal medicine, inhibits chemokine receptor function and suppresses human immunodeficiency virus type 1. Antimicrob Agents Chemother. 2003 Sep;47(9):2810-6.
• Shikonin production by extractive cultivation in transformed-suspension and hairy root cultures of Lithospermum erythrorhizon
  Annals of the New York Academy of Sciences, Vol 745, Issue 1 442-454,1994
• Genetic Engineering on Shikonin Biosynthesis: Expression of the Bacterial ubiA Gene in Lithospermum erythrorhizon
  Plant and Cell Physiology, 2000, Vol. 41, No. 8 911-919