“Distribution and pharmaceutical potential of polyketide photoantimicrobials from Cortinariaceae”

Fungi are an underestimated source of natural photosensitisers. In particular, polyketide pigment- producing fungi appear to use these metabolites as part of a sophisticated photoactivated chemical defence system [1]. Since fungi share their ecological niche with many microorganisms, we hypothesised that fungal photosensitisers are also active photoantimicrobials. Feature-based molecular network studies combined with a photoactivity assay highlighted species from the genus Cortinarius as highly potent. The next step was to screen the coloured fruiting bodies using a modified EUCAST protocol [2] against Candida albicans, Escherichia coli, and Staphylococcus aureus. A significant photoantimicrobial effect was detected for many extracts (c<25 µg/mL). Isolation of the responsible pigments based on photoactivity led to the identification of two new potent photoantimicrobials, i.e. emodin and dermocybin. The latter was active against S. aureus and C. albicans under green light irradiation (PhotoMic₅₃₀=39.5 µM and 2.3 µM, respectively) while being non-toxic to human cells. In summary, we will demonstrate the remarkable potential of fungal pigments against gram-positive and gram-negative bacteria and yeasts that cause unpleasant skin infections.

 

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Conflict of Interest

The authors declare no conflict of interest.

• References

• 1 Siewert B.. Does the chemistry of fungal pigments demand the existence of photoactivated defense strategies in basidiomycetes?. Photochemical & Photobiological Sciences 2021; 20: 475-488
• 2 Fiala J, Schöbel H, Vrabl P, Dietrich D, Hammerle F, Artmann DJ, Stärz R, Peintner U, Siewert B.. A New High-Throughput-Screening-Assay for Photoantimicrobials Based on EUCAST Revealed Unknown Photoantimicrobials in Cortinariaceae. Frontiers in Microbiology 2021; 12:

Publication History

Article published online:
16 November 2023