A toxic protein from Bryonia dioica Jacq. fruits: the brydiofin

A toxic protein isolated from Bryonia dioica Jacq. fruits is described. The fruit extract, obtained in phosphate buffer saline, in mild conditions, showed a strongly toxic activity after intraperitoneal injection of 0.4 mg per Balb/c mouse that was killed in eighteen minutes. The extract, filtered through a Bio-Gel P-60 column, presented a main peak that showed similar toxicity. When the material from this peak was analyzed in polyacrylamide slab gels, a single band corresponding to a molecular weight of about 66,000 was observed. The lethal effect of B. dioica fruit could be attributed to a protein that we called Brydiofin. The extracts from roots and leaves that did not present this toxicity showed no band in this molecular weight region.