Cortinarins in Cortinarius speciosissimus? A critical revision.

Fluorescent cyclic decapeptides, the so-called cortinarins, have been claimed to cause the toxicity of the deadly poisonous mushroom Cortinarius speciosissimus. As the structure elucidation described in the literature is doubtful in decisive parts, the proposed structures must be disputed. The present study demonstrates that the fluorescence is mainly due to ergosta-4,6,8(14),22-tetraen-3-one (8) and to photodecomposition products of the nephrotoxin orellanine (1). Moreover, we were not able to reproduce the isolation of fluorescent or any other cyclic peptides related to cortinarins from C. speciosissimus, by various methods.