Glucobrassicin enhancement in woad (Isatis tinctoria) leaves by chemical and physical treatments

Woad (Isatis tinctoria), a long-known dye plant, is a noticeable source of indolic compounds, bioactive molecules exploitable as fine chemicals. Among these, glucobrassicin and its derivatives seem to play an antitumoral role, especially against mammary cancer. Since different Brassicaceae, such as broccoli and cauliflower, which are present in the human diet, contain glucobrassicin, it would be interesting to study its metabolic pathway following the fate of the pure compound in vivo. At present such studies are prevented by the difficulties encountered in the purification, mainly due to the lack of a rich vegetable source. Synthetic production is complicated and expensive. This study aimed to assess the possibility of enhancing glucobrassicin in woad leaves through artificial wounding and fertilisation, in the greenhouse and open field, in order to obtain high levels of the compound suitable for its purification. Jasmonic acid treatment on young woad leaves of the ‘Casolavalsenio’ accession is confirmed to be highly effective in the enhancement of glucobrassicin content, especially in combination with N–S fertilisation, under greenhouse conditions. For large scale production in the open field, where the use of jasmonic acid would be economically prohibitive, an alternative method of stimulation could be advantageously represented by artificial wounding that is able to provoke a remarkable increase of the compound, giving more then 1% d.w., which would allow its purification.  2006 Society of Chemical Industry