Active principle

active principle

active principle n.
A constituent of a drug, usually an alkaloid or glycoside, on which the characteristic therapeutic action of the substance largely depends.
Historical Examples

Is it used by nerves as food, or used by lungs, heart, or any organ as an active principle in the magnetic or electric forces?
Philosophy of Osteopathy Andrew T. Still

The active principle of the seeds has not been satisfactorily isolated.
Poisons: Their Effects and Detection Alexander Wynter Blyth

If celery seed has any active principle it has never been isolated.
The Propaganda for Reform in Proprietary Medicines, Vol. 1 of 2 Various

It has been the blessing of France; it was its active principle down to 1820.
Rodin: The Man and his Art Judith Cladel

The active principle seems to be filicic acid and the ethereal oil.
Poisons: Their Effects and Detection Alexander Wynter Blyth

Down under the sod this active principle of life is still at work.
Letters of Peregrine Pickle George P. Upton

The passive principle is pure matter without qualities; the active principle is reason, or God.
Ancient and Modern Celebrated Freethinkers Charles Bradlaugh, A. Collins, and J. Watts

The nature of the active principle of aconite root does not appear to have been satisfactorily determined.
Cooley’s Cyclopdia of Practical Receipts and Collateral Information in the Arts, Manufactures, Professions, and Trades…, Sixth Edition, Volume I Arnold Cooley

It contains a substance called Aloetine, which some regard as its active principle.
The Commercial Products of the Vegetable Kingdom P. L. Simmonds

What is the active principle of your ‘sevens’—or haven’t you figured it out?
The City of Numbered Days Francis Lynde