PRINCIPLE n.
Any original inherent constituent which characterizes a substance, or gives it its essential properties, and which can usually be separated by analysis; -- applied especially to drugs, plant extracts, etc. Cathartine is the bitter, purgative principle of senna. Gregory. Bitter principle, Principle of contradiction, etc…
RELIEF n.
That which removes or lessenc evil, pain, discomfort, uneasiness, etc.; that which gives succor, aid, or comfort; also, the person who relieves from performance of duty by taking the place of another; a relay.