Identification and quantification of phenylpropanoid glycosides in Aloysia polystachya (Griseb and Moldenke) by HPLC-TQMS

Data on the chemical composition of Aloysia polystachya (Griseb. et Moldenke) are poor in the literature. It is an herbaceus plant, widely distributed in subtropical regions of South America where it is commonly known as “tè burro”. It is widely used as a dietary supplement or tea substitute and in folk medicine. Phenolic compounds characterization in plant matrix can be very difficult, owing to the bonding to different sugar moieties, or conjugation to form complex structures. Among the different methods available, high-performance liquid chromatography (HPLC) is preferable for the separation and quantification of polyphenolics. In present work the HPLC-MS characterization and quantification of the phenylpropanoid glycosides fraction, purified by Solid Phase Extraction (SPE), of Aloysia polystachya (Griseb. et Moldenke) extracts was performed. Three different MS techniques have been coupled to HPLC, to identify and quantify the compounds present in the extracts: ion trap mass spectrometry (Ion Trap LC/MS), and the quadrupole-time of flight high resolution mass spectrometry (Q-TOF HRMS) for the identification and HPLC-TQMS in MRM mode for the quantification, using verbascoside as reference standard. Nine phenylpropanoid glycosides were identified and quantified after SPME purification of methanolic extract of Aloysia polystachya leaves. Among them, the compounds forsythoside A, plantainoside C, purpureaside D, martynoside and its two isomers were identified here for the first time. The content of phenylpropanoid glycosides ranges from 3.3 mg/g for verbascoside to 0.08 mg/g for purpureaside D. The results present here could be helpful to assess the quality of Aloysia polystachya leaves. Knowledge of the content of phenylpropanoid glycosides could further contribute to the chemotaxonomy of the genus.