Woad (Isatis tinctoria) - An Ancient Crop For Green Chemistry: Indigo, Oil and Glucosinolates

Isatis tinctoria L., a biennial plant belonging to Brassicaceae family, is one of the earliest known sources of indigo dye, cultivated in Europe since the Middle Ages. Leaves of this plant can be harvested several times in the first year of growth, when plants are at the rosette stage. In the following spring, the plant produces a long stem, bearing yellow flowers on short racemes. The seeds are inside small siliculas that ripen in late summer. Besides indigo, the research interest is recently focusing on the use of some Isatis species, as oilseeds as source of oil rich in unsaturated fatty acids (Angelini et al., 2015), and for their indole glucosinolates (GLs) content (Hamburger, 2008). Regarding I. tinctoria, only few studies (Fréchard et al., 2001) have focused on investigating these aspects and, although the seeds are abundantly produced, they have not yet been fully characterised. On the basis of these considerations, a full valorisation of all plant components (leaves for indigo production and seeds for oil and GLs extraction) could represent a suitable strategy for obtaining added value products from this novel crop, according to the principles of green chemistry. So, the objective of the present study was to evaluate the performance of 17 Isatis tinctoria accessions in a location of Central Italy, focussing on: (i) biometric and productive characteristics; (ii) leaf content of Isatan B and Indican; (iii) siliculas and seed yields; (iv) seed oil content and fatty acid composition;(v) seed GL content and profile.