首页|Novel methods to characterise spatial distribution and enantiomeric composition of usnic acids in four Icelandic lichens

Novel methods to characterise spatial distribution and enantiomeric composition of usnic acids in four Icelandic lichens

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  • NSTL
  • Elsevier
? 2022 Elsevier LtdUsnic acid is an antibiotic metabolite produced by a wide variety of lichenized fungal lineages. The enantiomers of usnic acid have been shown to display contrasting bioactivities, and hence it is important to determine their spatial distribution, amounts and enantiomeric ratios in lichens to understand their roles in nature and grasp their pharmaceutical potential. The overall aim of the study was to characterise the spatial distribution of the predominant usnic acid enantiomer in lichens by combining spatial imaging and chiral chromatography. Specifically, separation and quantification of usnic acid enantiomers in four common lichens in Iceland was performed using a validated chiral chromatographic method. Molecular dynamics simulation was carried out to rationalize the chiral separation mechanism. Spatial distribution of usnic acid in the lichen thallus cross-sections were analysed using Desorption Electrospray Ionization-Imaging Mass Spectrometry (DESI-IMS) and fluorescence microscopy. DESI-IMS confirmed usnic acid as a cortical compound, and revealed that usnic acid can be more concentrated around the algal vicinity. Fluorescence microscopy complemented DESI-IMS by providing more detailed distribution information. By combining results from spatial imaging and chiral separation, we were able to visualize the distribution of the predominant usnic acid enantiomer in lichen cross-sections: (+)-usnic acid in Cladonia arbuscula and Ramalina siliquosa, and (?)-usnic acid in Alectoria ochroleuca and Flavocetraria nivalis. This study provides an analytical foundation for future environmental and functional studies of usnic acid enantiomers in lichens.

Alectoria ochroleucaCladonia arbusculaEnantioseparationFlavocetraria nivalisFluorescence microscopyImaging mass spectrometryMolecular dynamics simulationParmeliaceaeRamalina siliquosaUsnic acid

Xu M.、Oddsson S.、Gylfason A.E.、Snorradottir B.S.、Thorsteinsdottir M.、Omarsdottir S.、Olafsdottir E.S.、Oppong-Danquah E.、Tasdemir D.、Wang X.、Abdelrahman A.、Pedersen S.V.、Christensen E.A.、Szomek M.、Jameson C.J.、Murad S.、Andresson O.S.、Magnusson K.P.、Heidmarsson S.、de Boer H.J.

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Faculty of Pharmaceutical Sciences University of Iceland

GEOMAR Centre for Marine Biotechnology Research Unit Marine Natural Product Chemistry GEOMAR Helmholtz Centre for Ocean Research Kiel

Department of Chemical and Biomolecular Engineering University of Notre Dame

Department of Green Technology Faculty of Engineering University of Southern Denmark

Department of Biochemistry and Molecular Biology University of Southern Denmark

Department of Chemistry University of Illinois at Chicago

Department of Chemical Engineering Illinois Institute of Technology

Faculty of Life and Environmental Sciences University of Iceland

Icelandic Institute of Natural History Akureyri Division

Natural History Museum University of Oslo

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2022

10.1016/j.phytochem.2022.113210

Phytochemistry

Phytochemistry

CCR
ISSN：0031-9422
年,卷(期)：2022.200
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