Isolation and nephrotoxic studies of orellanine from the mushroom Cortinarius speciosissimus.

A nephrotoxic substance has been isolated from Cortinarius speciosissimus. The 1H-NMR and 13C-NMR mass spectra indicated the chemical structure to be 3,3',4,4'-tetrahydroxy-2,2'-bipyridine-N-N'-dioxide. The toxin was quantitated using reversed phase high performance liquid chromatography (HPLC) with electrochemical detection. The detection limit of this method was 500 pg, corresponding to a signal-to-noise ratio of 2.5. The toxin had an LD50 in mice of approximately 20 mg/kg i.p. Light microscopic examination of the kidneys of mice surviving treatment with the toxin showed interstitial nephritis and tubular necrosis.