Nephrotoxicity of orellanine, a toxin from the mushroom Cortinarius orellanus.

Pure orellanine extracted from the mushroom Cortinarius orellanus is highly toxic in mice both when given intraperitoneally (LD50 = 12.5 mg/kg) or per os (LD50 = 90 mg/kg). The kidneys of mice injected i.p. with orellanine show similar tubular necrosis to that obtained with whole mushroom given per os. This demonstrates that orellanine is the true, principal toxin of C. orellanus. The similarity of the structures of the toxin and of bipyridinium herbicides such as methylviologen (paraquat) or the nephrotoxic diquat led other authors to presume a similar mechanism for orellanine toxicity. Our study of the electrochemical behaviour of orellanine shows that its mechanism of action has to be different from that of these poisons.