Acute toxicity of braxin C, a bracken toxin, in guinea pigs.

Braxin C (BC), ptaquiloside, is a toxin isolated from bracken fern. In order to determine the characteristics of the acute BC toxicity, BC was administered as a single subcutaneous (s. c.) injection to guinea pigs, rats, and mice. BC (5 and 10 mg/kg) induced hemorrhagic cystitis and hematuria in guinea pigs, whereas no changes were observed in rats and mice administered BC at a dose of 100 mg/kg. In guinea pigs administered BC (5 and 10 mg/kg), marked edema and hemorrhage were noted in the lamina propria of urinary bladder, though these inflammatory changes were also observed in the tissues such as perirenal adipose tissues or abdominal wall. These findings clearly demonstrate that BC is a potent toxin capable of inducing hemorrhagic cystitis in guinea pigs, and suggest that it is one of the toxic principles responsible for bracken poisoning.