Abstract

1. The acute toxicity of riddelline has been determined in mice by intravenous injection.

2. Like other Senecio alkaloids so far studied, riddelline produces in mice central necrosis of the liver, ascites or hydrothorax, and pulmonary edema. There is also evidence of necrosis of cortical lymphocytes in the thymus.

3. Riddelline inhibits the isolated rabbit's small intestine and stimulates the isolated guinea pig's uterus. It causes a fall of blood pressure when injected by vein in pithed or barbitalized cats.