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CC BY-NC-ND 4.0 · Planta Med 2024; 90(07/08): 588-594
DOI: 10.1055/a-2249-9110
Biological and Pharmacological Activity
Original Papers

The Light-activated Effect of Natural Anthraquinone Parietin against Candida auris and Other Fungal Priority Pathogens[ # ]

Johannes Fiala
1   Department of Pharmacognosy, Institute of Pharmacy, Center for Molecular Biosciences Innsbruck, University of Innsbruck, Austria
,
Thomas Roach
2   Department of Botany, University of Innsbruck, Austria
,
Andreas Holzinger
2   Department of Botany, University of Innsbruck, Austria
,
Yurii Husiev
3   Leiden Institute of Chemistry, Leiden University, Netherlands
,
Lisa Delueg
1   Department of Pharmacognosy, Institute of Pharmacy, Center for Molecular Biosciences Innsbruck, University of Innsbruck, Austria
,
Fabian Hammerle
1   Department of Pharmacognosy, Institute of Pharmacy, Center for Molecular Biosciences Innsbruck, University of Innsbruck, Austria
,
Eva Sanchez Armengol
4   Department of Technology, Institute of Pharmacy, Center for Molecular Biosciences Innsbruck, University of Innsbruck, Austria
,
Harald Schöbel
5   Department of Biotechnology, MCI Innsbruck, Austria
,
Sylvestre Bonnet
3   Leiden Institute of Chemistry, Leiden University, Netherlands
,
Flavia Laffleur
4   Department of Technology, Institute of Pharmacy, Center for Molecular Biosciences Innsbruck, University of Innsbruck, Austria
,
Ilse Kranner
2   Department of Botany, University of Innsbruck, Austria
,
Michaela Lackner
6   Institute of Hygiene und Medical Microbiology, Medical University of Innsbruck, Austria
,
Bianka Siewert 
1   Department of Pharmacognosy, Institute of Pharmacy, Center for Molecular Biosciences Innsbruck, University of Innsbruck, Austria
› Author Affiliations
This research was funded in whole or in part by the Austrian Science Fund (FWF) 10.55776/P31915 to BS and 10.55776/P34181 to AH. For open access purposes, the corresponding author has applied a CC BY public copyright license to any author accepted manuscript version arising from this submission.
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Abstract

Antimicrobial photodynamic therapy (aPDT) is an evolving treatment strategy against human pathogenic microbes such as the Candida species, including the emerging pathogen C. auris. Using a modified EUCAST protocol, the light-enhanced antifungal activity of the natural compound parietin was explored. The photoactivity was evaluated against three separate strains of five yeasts, and its molecular mode of action was analysed via several techniques, i.e., cellular uptake, reactive electrophilic species (RES), and singlet oxygen yield. Under experimental conditions (λ = 428 nm, H = 30 J/cm2, PI = 30 min), microbial growth was inhibited by more than 90% at parietin concentrations as low as c = 0.156 mg/L (0.55 µM) for C. tropicalis and Cryptococcus neoformans, c = 0.313 mg/L (1.10 µM) for C. auris, c = 0.625 mg/L (2.20 µM) for C. glabrata, and c = 1.250 mg/L (4.40 µM) for C. albicans. Mode-of-action analysis demonstrated fungicidal activity. Parietin targets the cell membrane and induces cell death via ROS-mediated lipid peroxidation after light irradiation. In summary, parietin exhibits light-enhanced fungicidal activity against all Candida species tested (including C. auris) and Cryptococcus neoformans, covering three of the four critical threats on the WHOʼs most recent fungal priority list.

Keywords

Xanthoria parietina - Teloschistaceae - parietin - aPDT - photoantimicrobial - EUCAST - Candida auris - Metschnikowiaceae

# This work is dedicated to Professors Rudolf Bauer, Chlodwig Franz, Brigitte Kopp, and Hermann Stuppner for their invaluable contributions and commitment to Austrian Pharmacognosy.


Supporting Information

    A detailed description of materials, instruments, and analytical and isolation methods are available as Supporting Information. Also, procedures for experiments on stability, singlet oxygen yield, aggregation, uptake, and photoantimicrobial activity of parietin are described, followed by the experimental conditions of CLSM and quantification of RES and aldehydes. Information on the tested strains, characterisation of parietin, and detailed results of the performed experiments, including an interpretation on the influence of the solubility of parietin, are provided.

  • Supporting Information


Publication History

Received: 19 July 2023

Accepted after revision: 05 January 2024

Article published online:
06 June 2024

© 2024. The Author(s). This is an open access article published by Thieme under the terms of the Creative Commons Attribution-NonDerivative-NonCommercial License, permitting copying and reproduction so long as the original work is given appropriate credit. Contents may not be used for commecial purposes, or adapted, remixed, transformed or built upon. (https://creativecommons.org/licenses/by-nc-nd/4.0/)

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