THE PHYSIOLOGICAL ACTION OF THE PRINCIPLES ISOLATED FROM THE SECRETION OF BUFO ARENARUM

¹ From the Lilly Research Laboratories, Eli Lilly and Company, Indianapolis, and the Laboratory of Endocrine Research, Johns Hopkins University, Baltimore

From the secretion of the South American toad, Bufo arenarum, the following principles have been isolated and studied pharmacologically:

a. Cholesterol, which does not seem to be admixed with ergosterol.

b. Areno-bufagin, C₂₅H₃₄O₆, which has a digitalis-like action. The average fatal dose in 11 cats is 0.09 mgm. per kilogram. The minimal emetic dose in pigeons is 0.15 and that in cats 0.06 mgm. per kilogram. Areno-bufagin has a pressor action and a stimulating effect on isolated rabbits' intestines and guinea pigs' uteri. Its cardiac action does not seem to be persistent.

c. Areno-bufotoxin, C₃₉H₆₀O₁₁N₄, which also has a digitalis-like action. The minimal emetic dose in pigeons is 0.2, that in cats 0.15, and the average fatal dose in 13 cats 0.41 mgm. per kilogram. It raises the blood pressure and stimulates isolated rabbits' intestines and guinea pigs' uteri. Its action appears to be relatively more persistent than that of areno-bufagin.

d. Areno-bufotenine A, in the form of a flavianate, C₁₂H₂₀O₃N₂.-C₁₀H₆O₈N₂S, which is an indole derivative. It has a slight pressor action, increases the tone of cardiac contractions in frogs, and stimulates the isolated rabbits' intestines and guinea pigs' uteri.

e. Areno-bufotenine B, in the form of a flavianate, C₁₄H₁₈O₂N₃.-C₁₀H₆O₈N₂S, which is also an indole derivative. It stimulates isolated guinea pigs' uteri. Its pressor action is relatively feeble, and it has little effect on the isolated rabbit's intestines.

Evidence, both chemical and physiological, for the presence of epinephrine in the secretion has been presented.