LC‐PDA‐ESI‐MSⁿ analysis of phenolic and iridoid compounds from Globularia spp.

Abstract

Plants produce a great number of metabolites with potentially useful biological activities. Species from the genus Globularia (Plantaginaceae) are known as sources of different phenolic and iridoid compounds. Globularia alypum L. is a medicinal plant used as a healing agent in many Mediterranean countries. Similarities in phytochemical composition are often observed for related species. For Globularia spp., such findings were mostly based on identification of several isolated compounds from distinct species. To our knowledge, this is the first study that enables simultaneous comparison of phytochemical profiles from several members of the genus Globularia. Liquid chromatography-photodiode array detection-electrospray ionization-tandem mass spectrometry was used for the analysis of methanolic extracts of aerial parts obtained from four Globularia species (G. alypum, G. punctata, G. cordifolia and G. meridionalis). In total, 85 compounds were identified or tentatively identified based on comparison of their retention time, UV and MS (up to MS ) spectra to those of standard compounds and/or to literature data. Among these, high relative amounts of bioactive molecules such as globularin, globularifolin, asperuloside and verbascoside (acteoside) were found. Apart from providing new insights into the phytochemistry and chemotaxonomy of selected Globularia species, results of this study complement existing MS/MS spectral data and could enable easier mass spectrometric profiling of certain bioactive compounds such as iridoids and phenylethanoids in related plant species, genera and families. Copyright © 2016 John Wiley & Sons, Ltd.

Chemical fingerprint and bioactivity evaluation of Globularia orientalis L. and Globularia trichosantha Fisch. & C. A. Mey. using non‐targeted HPLC‐ESI‐QTOF‐MS approach

“…Moreover, 10‐ O ‐cinnamoyl esters of catalpol or catalpol derivatives, i.e. isomers of globularinin (peaks 56 and 86), globularin (peak 90) or globularioside (peak 95, Figure J) were tentatively identified in G. orientalis and G. trichosantha in agreement with Friščić et al . Among the iridoids as mentioned earlier, the only globularin was previously reported in G. trichosantha but not in G. orientalis .…”

“…G. alypum , G. punctata , G. cordifolia or G. meridionalis. Another verbascoside derivative (peak 52) was tentatively characterised for the first time in the samples under study. Its fragmentation occurred by the loss of [caffeic acid – H 2 O] − , [caffeic acid – H] − and [M – H 2 O – 162] − , correspond to the fragments at m / z 161, 179 and 459, respectively.…”

“…Rosssicaside A (peak 71) and isomers of verbascoside or isoverbascoside (peaks 74, 79 and 80) have been previously described in G. trichosantha but not in G. orientalis. In this regard, the fragmentation pattern of rossicadide A is shown in Figure (B). Concerning verbascoside or isoverbascoside isomers, they presented two main fragments at m / z 461 and 161 due to the loss of [M – H – caffeoyl] − and [179 – H 2 O] − , respectively.…”

“…Two isomers of calceolarioside A (desrhamnosyl verbascoside) (peaks 75 and 77) were only found in the G. orientalis sample. Their main ion fragments at m / z 161, 179 and 315 have been earlier reported as losses of anhydrocaffeic acid, caffeic acid and hydroxytyrosolglucoside, respectively . It is not the first time that this compound has been described in Globularia species, e.g.…”

“…Asperulosidic acid and derivatives are common compounds from G. aphyllanthes , G. trichosantha , G. alypum , G. punctata , G. cordifolia and G. meridionalis . In this regard, two isomers of asperulosidic acid (peaks 33 and 40) and two isomers of deacetylasperuloside (peaks 18 and 58) have been tentatively characterised in G. trichosantha and G. orientalis based on their MS spectra and data from the literature . Moreover, two isomers of the compound tentatively characterised as gentiopicroside were found in G. orientalis and only one isomer of that compound was found in G. trichosantha .…”