THE PHYSIOLOGICAL ACTION OF THE PRINCIPLES ISOLATED FROM THE SECRETION OF THE SOUTH AFRICAN TOAD (BUFO REGULARIS)

¹ From the Lilly Research Laboratories, Eli Lilly and Company, Indianapolis

From the parotid secretion of the South African toad, Bufo regularis, the following principles have been isolated and studied pharmacologically:

A. Cholesterol.

B. Regularo-bufagin, C₂₃H₃₄O₅, which has a digitalis-like action. The minimal emetic dose in pigeons is 0.3 mgm., that in cats 0.09 mgm., and the average fatal dose in cats is 0.15 mgm. per kilogram.

C. Regularo-bufotoxin, C₃₇H₆₀O₁₀N₄, which also has a digitalis-like action. The minimal emetic dose in pigeons is 0.35 mgm., that in cats 0.275 mgm., and the average fatal dose in 10 cats is 0.48 mgm. per kilogram. Both regularo-bufagin and -bufotoxin have a pressor action, and stimulate isolated smooth muscle organs. The cardiac action of regularo-bufotoxin seems to be relatively more persistent than that of regularo-bufagin.

D. Regularo-bufotenine, which is an indole derivative, in the form of a flavianate. It stimulates both the isolated rabbits' intestines and guinea pigs' uteri, and raises the arterial blood pressure, its activity being equivalent to about 5 per cent that of cino-bufotenine.

Evidence, both chemical and physiological, for the presence of epinephrine in the parotid secretion has been presented. By the blood-pressure method in pithed cats, it has been estimated that the dried secretion contains an average of 4.6 per cent of epinephrine, and that each toad has an average of 10.7 mgm. in its pair of parotid glands. Other parts of the back of the skin do not appear to contain any epinephrine.