Isatis tinctoria L. (Woad): Cultivation, Phytochemistry, Pharmacology, Biotechnology, and Utilization

Isatis tinctoria L. (Brassicaceae) is an herbaceous species with an ancient and well-documented history as an indigo dye source in temperate climates and as a medicinal plant. After centuries of intensive cultivation in Europe, the crop was completely abandoned in the late nineteenth century, when the production of synthetic indigo dye replaced that of natural indigo. Currently, the rising demand for naturally sourced dyes by the dyestuff industry, together with the use for medicinal purposes and the production of cosmetics, has prompted a renewed interest in this species. Herein, an overview of the research focused on the economically sustainable cultivation of I. tinctoria is given, primarily aimed at achieving maximum yields of indigo dye. Additionally, a detailed account is reported of all attempts in plant biotechnology studies for the enhanced production of bioactive compounds from I. tinctoria hairy root and shoot cultures as an alternative to plant raw materials. Furthermore, the main uses of this valuable species are described.