Two New Fumarprotocetraric Acid Lactones Identified and Characterized by UHPLC-PDA/ESI/ORBITRAP/MS/MS from the Antarctic Lichen Cladonia metacorallifera

Beatriz Sepúlveda,Alberto Cornejo,Carlos Areche,José Cheel,Daniela Bárcenas-Pérez

doi:10.3390/separations9020041

Abstract

Lichens are symbiotic organisms between algae and fungi, which are makers of secondary compounds named as lichen substances. Hyphenated techniques have significantly helped natural product chemistry, especially UHPLC/ESI/MS/MS in the identification, separation, and tentative characterization of secondary metabolites from natural sources. Twenty-five compounds were detected from the Antarctic lichen Cladonia metacorallifera for the first time using UHPLC-PDA/ESI/Orbitrap/MS/MS. Compounds 5 and 7 are reported as new compounds, based on their MS/MS fragmentation routes, and considered as fumarprotocetraric acid derivatives. Besides, ten known phenolic identified as orsellinic acid, ethyl 4-carboxyorsellinate, psoromic acid isomer, succinprotocetraric acid, siphulellic acid, connorstictic acid, cryptostictic acid, lecanoric acid, lobaric acid and gyrophoric acid are noticed for the first time in the Cladonia genus.

Highlights

Lichens are symbiotic organisms between algae or cyanobacteria and fungi
The identification of unknown secondary metabolites in metabolomics is the main bottleneck on the structural interpretation based on Mass spectrometry (MS)/MS spectra, making the identification an arduous time-consuming task
Our results demonstrate that the identification for lichen metabolites using UHPLCQ/Orbitrap/electro-spray ionization (ESI)/MS/MS is a fast and accurate methodology

Summary

Introduction

Lichens are symbiotic organisms between algae or cyanobacteria and fungi. Lichens are organisms that can grow everywhere on soil, on and within rocks, on tree barks, as well as on any inanimate object. Depsides, depsidones, dibenzofurans, depsones, anthraquinones, lactones and pulvinic acid derivatives have been isolated [4,5]. They have displayed multiple biological activities; for instance: antiulcer, gastroprotective, antibiotic, antiviral, antitumor, allergenic, plant growth inhibitory, antiherbivore, antileishmanial, anti-inflammatory, antioxidants, anti-trypanosoma and enzyme inhibitory activities [5,6,7]. Analyses of crude extracts were performed using chromatographic methods such as high-performance liquid chromatography (HPLC) in combination with various detection spectroscopic methods [8,9,10,11,12]. HPLC coupled to UV spectroscopy provide limited structural information when compounds are unknown [13].

Methods

Results

Conclusion