Analysis of the cyanolichenLichina pygmaeametabolites usingin situDART-MS: from detection to thermochemistry of mycosporine serinol

Abstract

Direct Analysis in Real Time DART-HRMS is here first applied to the detection of molecules from a lichen, Lichina pygmaea. The aim was to propose an innovative method of in situ detection of lichen secondary metabolites using the possibilities of elemental composition determination available when a DART source is interfaced with a TOF analyzer. Three kinds of samples have been submitted to DART ionization, i.e. an intact thallus, a powder obtained from the crushed lichen and an aqueous extract. In situ analysis of crushed lichen, yields an extensive chemical profile, comparable to what is obtained from the aqueous extract, comprising both major polar metabolites described in literature along with some other signals that could correspond to potentially unknown metabolites. One of the detected secondary metabolites, mycosporine serinol, underwent a dehydration reaction prior to its transfer in the gas-phase by DART ionization. The consideration of the thermal transfers involved in the DART ionization process and the possibility to record time-dependent mass spectra through the use of the TOF analyzer allowed establishing Arrhenius plots of this water molecule loss to obtain associated thermodynamic quantities. The low values of corresponding activation enthalpy (Δr‡Hm° of the order of 25 kJ mol(-1)) enabled formulating some assumption regarding a possible role of such metabolites in the lichen.

UHPLC‐HRMS/MS Based Profiling of Algerian Lichens and Their Antimicrobial Activities

“…[9 -11] Lichens have hence been used throughout time as medicines (the presence of antibiotic substances in lichens has been reported for the first time in 1944), food, fodder, dyes, perfume, spice, and for other miscellaneous purposes. [18] [19] It allows fast compound ionisation at atmospheric pressure in an open environment. [14] As many lichenic substances contain chromophores, UV detection has largely been used for their characterization in association with either thin layer chromatography or liquid chromatography (TLC or LC).…”

Morphological, Secondary Metabolite and ITS (rDNA) Variability within Usnic Acid‐Containing Lichen Thalli of Xanthoparmelia Explored at the Local Scale of Rock Outcrop in W‐Alps

“…Lichen chemical variability depends on either the difference of metabolite concentrations and replacements with related metabolites (same ‘chemosyndrome’) or biogenetically distinct metabolites (different ‘chemosyndrome’) . Advanced chromatography and mass spectrometry techniques strongly contribute to improve knowledge on LSMs; however, the qualitative and quantitative accuracy of these techniques has been marginally exploited to assess the chemical variability among/within circumscribed lichen taxa …”

In situDART-MS as a Versatile and Rapid Dereplication Tool in Lichenology: Chemical Fingerprinting ofOphioparma ventosa

“…Such features prompted us to try in situ DART-MS analyses for chemical profiling of lichens. We recently reported on in situ DART-HRMS analyses of sugar derivatives and nitrogen-containing metabolites in the cyanolichen Lichina pygmaea, highlighting its potential as an accelerated dereplication tool (Le Pogam et al, 2015b). To further evaluate the advantages offered by DART-HRMS in lichenology, its adequacy for in situ detection of archetypal lichen polyphenolics such as depsides and depsidones remained to be determined.…”