A substance that acts as an oestrogen only after it has been metabolised in the body to an active compound. ... (05 Mar 2000) ... 
(pro-es´tro-jәn) a substance without estrogenic activity but which is metabolized in the body to active estrogen.
Type: Term Pronunciation: prō-es′trō-jen Definitions: 1. A substance that acts as an estrogen only after it has been metabolized in the body to an active compound.