Fungal Photosensitizers – A new Scaffold of Tailor-made Photoantimicrobials?

New antimicrobials are needed to meet the challenges posed by increasing levels of antimicrobial resistance. While fungi are recognized as valuable source for antibiotics, their potential to produce photoantimicrobials has not been fully explored. Fungal photosensitizers were isolated from the colorful fruiting bodies of dermocyboid Cortinarius species. Their photoantimicrobial potential was evaluated using a high-throughput assay based on a modified EUCAST protocol. Photocytotoxicity studies and near infrared emission spectra were conducted to characterize the photochemical properties of our compounds. Potent, novel photoantimicrobials against bacteria and yeasts were identified with activities in the low micromolar/nanomolar range. In addition, action solely against microbes was demonstrated for selected fungal photosensitizers. Fungi are an underexplored source of promising photoantimicrobials with broad-spectrum antimicrobial activity.