cathartine

noun

1. (uncountable)A hypothetical substance formerly imagined to cause the bitterness and purgativeness of the dried leaves or pods of senna plants.

   “The sulphate of potash insoluble in this fluid, being separated by the filter; the excess of sulphuric acid was precipitated by acetate of lead; then, by decomposing this latter salt, by sulphuretted hydrogen, and again filtering and evaporating to dryness, the Cathartine, or purgative principle of senna, was obtained.”

   “In this state this residue has all the properties ascribed to cathartine; but it is easy to be convinced, from the colour and the avidity with which it attracts moisture, that the substance is not pure.”