It Is Not All about Alkaloids—Overlooked Secondary Constituents in Roots and Rhizomes of Gelsemium sempervirens (L.) J.St.-Hil

Abstract

Gelsemium sempervirens (L.) J.St.-Hil. is an evergreen shrub occurring naturally in North and Middle America. So far, more than 120 alkaloids have been identified in this plant in addition to steroids, coumarins and iridoids, and its use in traditional medicine has been traced back to these compound classes. However, a comprehensive phytochemical investigation of the plant with a special focus on further compound classes has not yet been performed. Therefore, the present study aimed at an extensive HPLC-MSn characterization of secondary metabolites and, for the first time, reports the occurrence of various depsides and phenolic glycerides in G. sempervirens roots and rhizomes, consisting of benzoic and cinnamic acid derivatives as well as dicarboxylic acids. Furthermore, mono- and disaccharides were assigned by GC-MS. Applying the Folin–Ciocalteu assay, the phenolic content of extracts obtained with different solvents was estimated to range from 30 to 50% calculated as chlorogenic acid equivalents per g dry weight and was related to the DPPH radical scavenging activity of the respective extracts. Upon lactic acid fermentation of aqueous G. sempervirens extracts, degradation of phenolic esters was observed going along with the formation of low-molecular volatile metabolites.