Identification of phenylpropanoid glycosides from Aloysia polystachya (Griseb. et Moldenke) by HPLC-MS analysis

Introduction Data on the chemical composition of Aloysia polystachya (Griseb. et Moldenke) are poor in the literature. Phenolic compounds characterization in plant matrix can be very difficult, owing to bond to different sugar moieties, or conjugation to form complex structures. Despite a great number of investigations, also the separation and the simultaneous determination of polyphenolics of different groups remain difficult. Among the different methods available, high-performance liquid chromatography (HPLC) is preferable for the separation and quantification of polyphenolics. The HPLC-MS characterization of the phenylpropanoid glycosides fraction, purified by Solid Phase Extraction (SPE), in Aloysia polystachya (Griseb. et Moldenke) extract was performed. Method Two different MS techniques have been coupled to HPLC, to identify the compounds present in the extract, and support tentative structure identification: ion trap mass spectrometry (Ion Trap LC/MS), and the quadrupole-time of flight high resolution mass spectrometry (Q-TOF HRMS). Results / Discussion / Conclusion Nine phenylpropanoid glycosides were identified in methanolic extract of the Aloysia polystachya (Griseb. et Moldenke) leaves. Among them, the compounds forsythoside A, plantainoside C, purpureaside D, martynoside and its two isomers were identified here for the first time. The results present here could be helpful in the future developing and validating of an analytical method to quantify the isolated compounds, and to assess the quality of Aloysia polystachya (Griseb. et Moldenke) leaves. Knowledge of the content of phenylpropanoid glycosides could further contribute to the chemotaxonomy of the genus.