Abstract Callus cultures of Echium lycopsis were shown to produce a large amount of a mixture of red pigments consisting of five esterified derivatives of 5, 8-dihydroxy-2-(1- hydroxy-4-methyl-3-pentenyl)-1, 4-naphthoquinone. Examination of the absolute configuration of these compounds revealed that the cultures produced both the R-form (shikonin) and the S-form (alkannin) in various ratios depending upon the esterified ...
