Isolation of the intermediates and related metabolites of shikonin biosynthesis from Lithospermum erythrorhizon cell cultures.

Compounds biogenetically related to shikonin in both the shikonin-producing and nonproducing cell suspension cultures of Lithosperumum erythrorhizon were investigated to compare their secondary metabolism. From the shikonin-producing cultures two intermediates of shikonin biosynthesis, m__--geranyl-p__--hydroxybenzoic acid and geranylhydroquinone, and two shikonin-related metabolites, shikonofuran E and a new compound named deoxyshikonofuran were isolated. On the other hand, only m__--geranyl-p__--hydroxybenzoic acid was isolated from the cultures that did not produce shikonin. This suggests that a biosynthetic step leading to geranylhydroquinone from m__--geranyl-p__--hydroxybenzoic acid through decarboxylation is repressed in these cultures.