A vast array of different pigments causes the splendid colors of mushrooms (Basidiomycetes).
While plenty of these colorants are chemically elucidated, their pharmaceutical potential
is only partly studied. Based on the structural similarity to well-known photosensitizers
(e.g. bisanthrones and anthraquinones) we hypothesized that fruiting bodies of the
subgenus dermocyboid Cortinarii are a promising source for new photosensitizers, which
can be utilized as photopharmaceuticals.
To test this hypothesis, extracts of dried fruiting bodies of several European dermocyboid
Cortinarii were prepared and submitted to a photo-activity screening workflow [1]. In detail, the chemical profile of light-absorbing metabolites was analyzed, the
ability to produce singlet oxygen was tested, and the photocytotoxicity was evaluated.
Based on the photo-activity workflow, the most prominent dermocyboid species was selected
and several photosensitizers isolated by applying a bioactivity-guided workflow. Chemical
analysis disclosed that the most prominent photosensitizer is a biphyscion. While
it is non-toxic in the dark, it showed e.g. an EC50 of 0.7 µM under blue light irradiation (468 nm, 9.3 J/cm2) against cells of a lung cancer cell-line (A549).
In sum, starting with a hypothesis based on the structural similarity between well-established
photosensitizers and the coloring principles of fruiting bodies we were able to assign
a new pharmaceutical activity to selected fungal pigments.
The FWF (Austrian Science Fund project P 31,915, BS), the TWF (Tyrolean Science Fund),
and the University of Innsbruck (Nachwuchsförderung,BS) are acknowledged for the financial
support.
