[Tinctorial plants, their therapeutic applications in ancient times. The particular case of Isatis].

Three tinctorial plants were systematically used in Europe in the Middle Ages: Woad, Madder and Weld. Their therapeutic properties were also described by classical authors, least two of them were known on all the continents: woad for blue and madder for red. Modern laboratories have been able to show clearly some therapeutic active principles derived from the indol of woad (Isatis sp.).