As a dyestuff for foods, alkanet was used until a few years ago, when the European Union banned it. Alkanet has also been used for a violet dye on silk, as discovered by a dye analysis of knitted silk from Central Asia . The story of the enantiomeric naphthoquinone natural products alkannin can be traced back many centuries. In fact, the story comprises two sub-plots that have run remarkably parallel courses in Europe and the Orient, being united only in the 20th century. In Europe , the S enantiomer, alkannin, is found in the roots of the plant Alkanna tinctoria Tausch, also known as Anchusa tinctoria , and in common English as alkanet. The compound is a major component of the deep red pigments that are easily extracted from the roots of the plant.
