Measurement of Phenolic Compounds and Their Effect on Shikonin Production in Lithospermum Cultured Cells

Shikonin production by Lithospevmum cell cultures is induced by transferring the cells into production medium. Six phenolic compounds, p-hydroxybenzoic acid, caffeic acid, sinapic acid, ferulic acid, syringaldehyde, and salicyclic acid, were detected in both shikonin-producing and non-producing cells. Their contents in the former were much lower than those in the latter except for salicylic acid, the content of which strongly increased when cells were producing shikonin. The cell wall fraction, after alkaline hydrolysis, gave two phenolic compounds, p-hydroxybenzoic acid and caffeic acid. Their contents were much higher in shikonin-producing cells than in shikonin-free cells. Of these compounds, exogenous addition of p-hydroxybenzoic acid increased shikonin production in the production medium. Although it is a precursor of shikonin, the increment of shikonin produced was much larger than the administered p-hydroxybenzoic acid, suggesting this compound has a stimulatory effect on shikonin biosynthesis at a low concentration.