Targeted and untargeted phytochemistry of Ligusticum canbyi: indoleamines, phthalides, antioxidant potential, and use of metabolomics as a hypothesis-generating technique for compound discovery.

Ligusticum canbyi (J.M. Coult & Rose) is a medicinal understory forest species used in traditional rituals and ceremonies for spiritual enlightenment and improved mental health. Very little is known about the phytochemical complexity or diversity of L. canbyi tissues or extracts. The current study was undertaken to determine whether Ligusticum tissues and extracts contain specifically targeted biologically active phytochemicals such as: melatonin, serotonin, Z-ligustilide, E-3-butylidenephthalide, and ferulic acid and to investigate the untargeted phytochemical complexity of the entire L. canbyi metabolome. The results of these studies identified melatonin and serotonin in roots and shoots of L. canbyi and L. porteri. Z-ligustilide, E-butylidenephthalide, and ferulic acid were quantified in roots and shoots of L. canbyi. Metabolomic analysis detected approximately 34,000 compounds in each L. canbyi extract, and predictive analysis suggests the presence of more than 70 putative phthalide metabolites. The relative contribution of the known metabolites and the unknown markers to the antioxidant potential of root and shoot tissues were compared, and it was determined that the majority of the antioxidant capacity could be attributed to ferulic acid in the tissues. These data provide new understandings of the phytomedicinal composition and potential mechanisms of activity of L. canbyi extracts and tissues.