Journal
PHYTOCHEMISTRY
Volume 200, Issue -, Pages -Publisher
PERGAMON-ELSEVIER SCIENCE LTD
DOI: 10.1016/j.phytochem.2022.113210
Keywords
Alectoria ochroleuca; Cladonia arbuscula; Flavocetraria nivalis; Ramalina siliquosa; Parmeliaceae; Usnic acid; Imaging mass spectrometry; Fluorescence microscopy; Enantioseparation; Molecular dynamics simulation
Categories
Funding
- European Union [606895]
- Icelandic Research Fund [185442051]
- Bergthora and Thorsteinn Scheving Thorsteinsson Fund
- Eppley Foundation
- Novo Nordisk Foundation (NNF) [NNF18SA0032928]
Ask authors/readers for more resources
This study characterized the spatial distribution of the predominant usnic acid enantiomer in lichens in Iceland using spatial imaging and chiral chromatography techniques. The results revealed the distribution of usnic acid in lichens and provided an analytical foundation for future environmental and functional studies of usnic acid enantiomers in lichens.
Usnic 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.
Authors
I am an author on this paper
Click your name to claim this paper and add it to your profile.
Reviews
Recommended
No Data Available