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 MS n experiments, and reference compounds. Reference : 1. Hamburger, M. (2002), Phytochem. Rev. 1: 333–344.