Ouabain

Ouabain is a crystalline glucoside separated from the wood and roots of Carissa shimperi, a plant growing on the east coast of Africa. It is intensely poisonous, a twelfth of a grain being sufficient to kill a rabbit. It acts upon the heart in the same way that digitalis does, and has been employed in medicine as a substitute for digitalis, and also to lessen the violence of the paroxysms in hooping-cough. The Somalis make an extract of the wood and roots for an arrow-poison.