FORMATION OF STEREOISOMERIC MIXTURES OF NAPHTHOQUINONE DERIVATIVES IN ECHIUM LYCOPSIS CALLUS CULTURES

Article abstract of DOI:10.1016/0031-9422(83)83022-2

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 derivative, although the overall ratio for the total derivatives was ca 1:1.On the other hand, all the corresponding derivatives produced by Lithospermum cultures were primarily of the R-form.It was also demonstrated that pigment formation in Echium cultures was inhibited by either white or blue light as well as by the synthetic auxin 2,4-D as in the case of Lithospermum cultures. Key Word Index - Echium lycopsis; Lithospermum erythrorhizon; Boraginaceae; callus cultures; biosynthesis; shikonin; alkannin; naphthoquinone pigments; stereoisomers.