A comprehensive metabolite profiling of Isatis tinctoria leaf extracts

Woad (Isatis tinctoria L., Brassicaceae) is an ancient indigo dye and medicinal plant, which has been used and cultivated in the temperate climate zones of Europe since antiquity. The anti-inflammatory potential of Isatis tinctoria was recently confirmed in a broad-based pharmacological profiling [1], in various animal models, and in a clinical pilot study. The alkaloid tryptanthrin (1), indolin-2-one 2, and γ-linolenic acid were identified as inhibitors of COX-2, 5-LOX, leucocytic elastase, and of histamine release from mast cells. To further characterize the active leaf extracts, we carried out a comprehensive metabolite profiling. Extracts were analyzed by gradient HPLC combined with photodiode array (PDA), evaporative light scattering (ELSD) and mass spectrometry (ESI-MS and APCI-MS in positive and negative ion modes) detection. Over 80 peaks were resolved. A majority of peaks could be assigned to structural classes such as alkaloids, fatty acids, flavonoids, porphyrins and carotenoids, and a large number of compounds were identified with the aid of UV-vis spectra, MS and MSⁿ experiments, and reference compounds.

Reference: 1. Hamburger, M. (2002), Phytochem. Rev. 1: 333–344.