Studies on Shikon. III. New Furylhydroquinone derivatives, Shikonofurans A, B, C, D and E, from Lithospermum erythrorhizon Sieb. et Zucc

Five new furylhydroquinone derivatives, named shikonofurans A, B, C, D and E, were found in the root of Lithospermum erythrorhizon SIEB. et ZUCC. (Boraginaceae). Shikonofuran A was proved to have the structure I, shown in Chart 1, by direct comparison of the spectral data of its diacetate with those of echinofuran leucoacetate. The structures of the other compounds were established on the basis of spectral and chemical evidence as II, III, IV and V, shown in Chart 1.